# Setting up a PC based loudspeaker measurement system



## npdang

*Setting up a PC based loudspeaker measurement system*

*Introduction.*

Setting up a PC based loudspeaker measurement system is a very easy, accurate, and cost effective alternative to the days of using unreliable “Rat shack” spl meters, or expensive and cumbersome RTA’s as an aid for tuning your car. It also makes tuning and set up of your next car audio system a breeze. You no longer have to play guessing games with where and how to set your equalizer, crossover, or time alignment. It’s also an extremely useful tool for finding problem areas in your car, so you can know why your bass isn’t tight, your midrange sounds muddy, or how to fix that harsh sounding tweeter.

*Equipment.*

Probably the first thing you’re wondering is, what kind of gear do I need to make this all happen and how much is this going to cost me? Well, to get started you’re going to need the following basic items :

*A.* Full duplex (meaning it can record and play simultaneously) soundcard with a stereo line input and output. In fact, simpler is often better. Soundcards with all kinds of funny 3d or special effects processing can interfere with your measurements if they can’t be reliably turned off. Oftentimes, the integrated soundcard that comes with your computer is perfect and there is no need to purchase an aftermarket sound card.

However, if you must buy an add-on card for one reason or another, my recommendation is M-Audio’s usb transit. It’s cheap, portable, and very reliable. Expect to pay around $80 for a new unit.










http://www.m-audio.com/products/en_us/Transit-main.html

*B.* Next you will need a microphone, and a power supply or “pre-amp” for the mic. A very popular, low budget choice that yields fairly consistent and accurate results is the Behringer ecm8000 mic, combined with the M-audio Audio Buddy pre-amp. Just like with the soundcard, you want to avoid using any preamp that feature distortion or special effects generators (such as tube pre-amps). This combo has been tested against laboratory grade equipment, and should guarantee great results for a very small cash investment.









http://www.behringer.com/ECM8000/index.cfm?lang=ENG










http://www.m-audio.com/products/en_us/AudioBuddy-main.html

And for those with a little more money looking for an all in one sound card and mic preamp, you can check out the M-Audio MobilePre USB for $180 msrp.










http://www.m-audio.com/products/en_us/MobilePreUSB-main-1.html


*C.* Measurement software. Probably the most important and yet least understood. The first question to ask is, what do I want to do with this setup? Price, and ease of use is also important. And lastly, do you want to use a RTA or MLS based measurement software. 

Generally speaking, a RTA is more convenient because all you need to do is burn a “pink noise test cd”, and play that on your headunit. Then you turn on your mic, and you are given a 1/3 octave frequency response graph to look at. It’s as simple as that.

A MLS based system can give you a FAR greater amount of information and flexibility (especially time domain info and not just frequency response), but it will require you to connect your soundcard’s line output to the input of your audio system before any crossovers, eq, or processing is used. The way it works is that the software generates the test signal, sends it out through your soundcard, and into your stereo. 

Here is a list of some commonly used software packages, their general capabilities, and pricing:

LspLab v3.01

My personal favorite. It does nearly everything you could want, and is fairly straightforward and simple to use. Includes box, crossover, and measurement software. Unfortunately, the demo doesn't give you very good frequency resolution.

http://www.lsp-lab.com/

WinMLS 2000 – The standard personal license is just $79. A great MLS package for the beginner. Easy to setup, and use. The interface is fast and quick to learn. This will allow you to:

-	take frequency response measurements
-	measure distortion
-	see what the frequency response of your setup looks like without reflections
-	configure time alignment by measuring the arrival time of each speaker
-	create waterfall plots
-	oscilloscope

http://www.winmls.com

Sample Champion – Student license $149 euro. Home license $199 euro. Not quite as easy to learn as WinMLS, but with far more options. Same features as WinMLS plus the following:

-	t/s parameter calculation
-	option for mic and soundcard calibration which allow you to take more accurate frequency response measurements 
-	RTA capability
- easier to use, built-in distortion analyser

http://www.purebits.com

TrueRTA - $40 license fee for the basic software. Very simple to use. Your basic RTA right here, but not much else. Other than taking 1/3 octave frequency response measurements, there’s not much else to do with it.

http://www.trueaudio.com

SpectraPlus – A software very similar to TrueRta, but with a few more features such as a spectrum/fft analyzer, and distortion analyzer. A spectrum analyzer is a little different from a RTA. Where a RTA shows you frequency response in 1/3rd octave increments, a spectrum analyzer shows you frequency response in set increments, such as 10hz, or 1hz. 

http://www.telebyte.com/pioneer/

Speaker Workshop – A free program. It will allow you to take frequency response measurements, calculate t/s parameters, and perform distortion analysis. Clunky and non-intuitive interface, but the price can’t be beat. You can read the manual here: http://www.audiodiycentral.com/resource/SWmanual/Speaker Workshop Manual 1.0.zip

http://www.speakerworkshop.com

*D.* Last but not least, you will need cables to wire this whole thing up. 

-	A cable to connect the mic to the mic pre-amp
-	A cable to connect the mic pre-amp to your soundcard input
-	A cable to connect the soundcard output to your amplifier/processor (not required if you’re using an RTA and test cd w/pink noise)
-	A mic stand to hold your mic while taking measurements (optional)[/i]


----------



## Hobbes26

WinMLS doesn't give you an MLS excitation signal in the $99 version - you have to get the 4th level Pro to get that.

Otherwise, I guess you use pink noise to get FR?


----------



## npdang

I guess prices have gone up? I paid $79 for my full copy of WinMLS 2000.


----------



## Hobbes26

Ah... I wonder how much better WinMLS 2004 is, compared to 2000, considering it's quite the jump in price - to get MLS capability at least.


----------



## npdang

Hobbes26 said:


> Ah... I wonder how much better WinMLS 2004 is, compared to 2000.


As far as I can tell, it doesn't really do anything new that I would be interested in. Sine sweep excitation takes forever compared to MLS. Distortion is kind of nice, but that's only if you're too lazy to compute it yourself from the FFT. Uhm... other than that a very high price increase and really nothing else I would use.

Also, you can still buy the old WinMLS 2000 standard personal for $79. Honestly, the only thing I like about WinMLS is how easy it is to stack and format multiple measurements onto one display. Like if you're taking multiple frequency response measurements, you can shift one up +5db the other down -5db, normalize them all to 0, stack them on top of each other or only display one at a time, etc.

Value wise, though I think Sample Champion or Sound Easy gives you the most for your money. Sound Easy interface just sucks... not alot of customization with respect to displaying output either, but it's a very powerful and comprehensive package. Sample Champ is pretty good, but no xover stuff, and it's a lil harder than WinMLS to overlay graphs and edit their appearance. If I had money, I'd just buy LMS and be done with it


----------



## Hobbes26

LMS?!? Full length ISA card based? Swept sine wave measurement? I'm partial to using the MLS methods - and rather have it NOT on an ISA card. We've had enough problems with our MLSSA measurement card (actually, problems with the OLD computers we've had it installed in).

You actually bought all of those programs? I haven't heard much about SoundEasy... SampleChampion looks decent.

Know how much a Praxis setup costs? 

Found a 'full' Clio setup for $700 at audioxpress.com (ClioWIn Lite? Wonder how up to date it is.). It's also sold at e-speakers.com (~$2k for hardware and software). Have you used Clio? Seems like a good package for everything you need to do a measurement.


----------



## npdang

Hobbes26 said:


> LMS?!? Full length ISA card based? Swept sine wave measurement? I'm partial to using the MLS methods - and rather have it NOT on an ISA card. We've had enough problems with our MLSSA measurement card (actually, problems with the OLD computers we've had it installed in).
> 
> You actually bought all of those programs? I haven't heard much about SoundEasy... SampleChampion looks decent.
> 
> Know how much a Praxis setup costs?
> 
> Found a 'full' Clio setup for $700 at audioxpress.com (ClioWIn Lite? Wonder how up to date it is.). It's also sold at e-speakers.com (~$2k for hardware and software). Have you used Clio? Seems like a good package for everything you need to do a measurement.


Praxis I think is $800 with the audpod? That would be my second choice after LMS.

I didn't like Clio because I thought it was a bit pricey, but it does come with a calibrated mic/pre and the spl measurements are absolute. Doesn't support the variety of post processing and stimulus that Praxis does though IIRC.


----------



## Hobbes26

npdang said:


> Hobbes26 said:
> 
> 
> 
> LMS?!? Full length ISA card based? Swept sine wave measurement? I'm partial to using the MLS methods - and rather have it NOT on an ISA card. We've had enough problems with our MLSSA measurement card (actually, problems with the OLD computers we've had it installed in).
> 
> You actually bought all of those programs? I haven't heard much about SoundEasy... SampleChampion looks decent.
> 
> Know how much a Praxis setup costs?
> 
> Found a 'full' Clio setup for $700 at audioxpress.com (ClioWIn Lite? Wonder how up to date it is.). It's also sold at e-speakers.com (~$2k for hardware and software). Have you used Clio? Seems like a good package for everything you need to do a measurement.
> 
> 
> 
> Praxis I think is $800 with the audpod? That would be my second choice after LMS.
> 
> I didn't like Clio because I thought it was a bit pricey, but it does come with a calibrated mic/pre and the spl measurements are absolute. Doesn't support the variety of post processing and stimulus that Praxis does though IIRC.
Click to expand...

What makes LMS so good?


----------



## npdang

Hobbes26 said:


> npdang said:
> 
> 
> 
> 
> 
> Hobbes26 said:
> 
> 
> 
> LMS?!? Full length ISA card based? Swept sine wave measurement? I'm partial to using the MLS methods - and rather have it NOT on an ISA card. We've had enough problems with our MLSSA measurement card (actually, problems with the OLD computers we've had it installed in).
> 
> You actually bought all of those programs? I haven't heard much about SoundEasy... SampleChampion looks decent.
> 
> Know how much a Praxis setup costs?
> 
> Found a 'full' Clio setup for $700 at audioxpress.com (ClioWIn Lite? Wonder how up to date it is.). It's also sold at e-speakers.com (~$2k for hardware and software). Have you used Clio? Seems like a good package for everything you need to do a measurement.
> 
> 
> 
> Praxis I think is $800 with the audpod? That would be my second choice after LMS.
> 
> I didn't like Clio because I thought it was a bit pricey, but it does come with a calibrated mic/pre and the spl measurements are absolute. Doesn't support the variety of post processing and stimulus that Praxis does though IIRC.
> 
> Click to expand...
> 
> What makes LMS so good?
Click to expand...

I don't like swept sine measurements since they take so long, but supposedly they have higher noise immunity than MLS. But the biggest feature of LMS is all the post processing features you get... especially the non-linear measurements. Interface is pretty straightforward as well. But yeah that ISA card is a big pain.

For most people that just want something to use in the car I"d probably just learn Speakerworkshop since it's free and it does actually do quite a bit.


----------



## Hobbes26

npdang said:


> I don't like swept sine measurements since they take so long, but supposedly they have higher noise immunity than MLS. But the biggest feature of LMS is all the post processing features you get... especially the non-linear measurements. Interface is pretty straightforward as well. But yeah that ISA card is a big pain.
> 
> For most people that just want something to use in the car I"d probably just learn Speakerworkshop since it's free and it does actually do quite a bit.


Ah, nearly forgot this was a diyMOBILEaudio site... . In-car measurements are kinda tricky. I was speaking in terms of more general applications of speaker measurement.

I should try out Speaker Workshop - have you used it extensively?


----------



## npdang

Hobbes26 said:


> npdang said:
> 
> 
> 
> I don't like swept sine measurements since they take so long, but supposedly they have higher noise immunity than MLS. But the biggest feature of LMS is all the post processing features you get... especially the non-linear measurements. Interface is pretty straightforward as well. But yeah that ISA card is a big pain.
> 
> For most people that just want something to use in the car I"d probably just learn Speakerworkshop since it's free and it does actually do quite a bit.
> 
> 
> 
> Ah, nearly forgot this was a diyMOBILEaudio site... . In-car measurements are kinda tricky. I was speaking in terms of more general applications of speaker measurement.
> 
> I should try out Speaker Workshop - have you used it extensively?
Click to expand...

I did play with it for like 15 mins... but I didn't like the interface. Other than that, AFAIK it's accurate and does a buncha stuff like xover etc.


----------



## blackreplica

hobbes> Based on cheapboy's recommendation 
via email i decided to give speakerworkshop a try. Cheap is right, the thing is damned hard to use. Very non-intuitive interface. BUT its free. And recently, i managed to get a hold of the unofficial speakerworkshop manual (try searching for it on the web, its a 10mb word doc compiled by an enthusiast). The manual is EXTREMELY detailed, but its over 200 pages long so lets just say the learning curve on this software is very steep. I just spent last night reading about 10 pages at the beginning and i think i have figured out how to to mls speaker measurements on it. i didnt have an mic or speaker(to measure) connected to my laptop but when i hit the measure-frequency-response button the thing made a short pink noise burst for less than half a second or something(if that is an mls signal then i suppose i am on the right track) and spit out an FR chart for me. It was a horribly jagged response, but i presume its my laptop soundcard FR which is probably crap anyway since there was no mic hooked up. But hey, i think it works, and if it can take Fr measurements, then i guess its good enough for in-car tuning. of course the functionality is far more advanced than that. You can do pretty much everything from passive cicuit design, enclosure design, impedance/ T/S measurements, distortion, a whole lot of other stuff. of course, i have no idea how to measure those yet. have to finish reading the manual which will probably take me another 5 years or so LOL but hey at least its free. hope this helps


----------



## npdang

Performing a mls measurement should just be (more or less) a one click process. 

You really don't have to read through the entire manual... alot of it is just good misc. background info. Just skip straight to the part about taking frequency response measurements.

If you have a loopback cable you can plug the output of your soundcard into the line input and take a fr measurement of your card


----------



## blackreplica

Yea thankfully the MLS measurement was a one click process, but there was some work to be done beforehand. You have to actually create a speaker file in the project tree, then do a bit of setup then finally the MLS itself. 

The interface is really clunky though, and the thing i dont like also is the difficulty in joining different chart measurements together. So far the software is just ok for me, so i think i may actually go for WinMLS 2000 instead. the price is not that expensive anyway. Software packages like Soundeasy at more than 200+ is definitely out of the question for me


----------



## blackreplica

OK i managed to mess around with a trial version of winmls 2000 personal just now. I couldnt do much besides clicking buttons though since i havent got the unlock code for the trial version yet but at first glance things look a LOT more intuitive. not only does the layout make sense, but the help file is really well organised and detailed as well. Once winmls sends me the unlock code i'll be able to know more. 

BTW cheap, do you typically use pre-emphasis when doing mls measurements? Also, would you need to calibrate anything in the software if all you were using it for was mls, impulse, and maybe THD/waterfall measurements? or is calibration just to obtain accurate spl readings?


----------



## npdang

blackreplica said:


> OK i managed to mess around with a trial version of winmls 2000 personal just now. I couldnt do much besides clicking buttons though since i havent got the unlock code for the trial version yet but at first glance things look a LOT more intuitive. not only does the layout make sense, but the help file is really well organised and detailed as well. Once winmls sends me the unlock code i'll be able to know more.
> 
> BTW cheap, do you typically use pre-emphasis when doing mls measurements? Also, would you need to calibrate anything in the software if all you were using it for was mls, impulse, and maybe THD/waterfall measurements? or is calibration just to obtain accurate spl readings?


Also give lsplab a try. The free version actually offers quite alot of functionality.

The only thing I would worry about is the time latency calibration... and only if your sound card doesn't have a fixed time delay between when it starts playing a signal, and when it begins to record. 

It's really easy to test this with a loopback cable. The impulse response should be at exactly the same position everytime you take a measurement. If it moves, then you would need to use a loopback cable on the left or right channel to "calibrate" the time delay of your soundcard.


----------



## blackreplica

I'll probably give that a try later with speakerworkshop. I never thought of trying the loopback method up till you recommended it(i've got an earphone cable with 2 male ends somewhere at home). I'll measure the latency but i presume this wont become an issue once you use an external sound card like the m-audio usb transit? Cos i was planning on getting one anyway. i seriously dont trust the quality of the built in sound card on my laptop.


----------



## npdang

The transit is pretty good. It has a fixed time delay. At least when I measured it about 20x I got the same delay each time.

I'd just skip over speakerworkshop. Never really liked that interface.

Anyways, you'd be surprised to know that the built-in soundcard on alot of motherboards is quite good for measuring.... considerably better than the soundblaster type stuff anyways. The audigy I had was so bad... the time delay was different for each measurement just screwed everything up.


----------



## blackreplica

Bah! Screw the internal cards, they suck(well, mine does)  

OK now i really need to thank you. I've gone thru so many different loudspeaker measurement programs and lspLAB 3 seems to be THE one!

I just downloaded it, and its sooooo easy to use, plus its free! There are some bugs with the passive crossover/enclosure simulator portions but for MLS/impulse/CSD this thing is just plain AWESOME!!! I dont think it has THD measurements though, or maybe i just havent found it yet. not that it matters for setting up car audio. Note that this software will need the free 3.01 upgrade for it to work with the M-Audio Transit sound card

The website is here for those interested: 
www.wavecapture.com

Its still early, but IMO this software is awesome. free, nice looking, intuitive, very easy to use. i esp like the spectrum analyser/RTA functions built in as well. Programs like speakerworkshop only use MLS and nothing else....  

great recommendation!!


----------



## npdang

blackreplica said:


> Bah! Screw the internal cards, they suck(well, mine does)
> 
> OK now i really need to thank you. I've gone thru so many different loudspeaker measurement programs and lspLAB 3 seems to be THE one!
> 
> I just downloaded it, and its sooooo easy to use, plus its free! There are some bugs with the passive crossover/enclosure simulator portions but for MLS/impulse/CSD this thing is just plain AWESOME!!! I dont think it has THD measurements though, or maybe i just havent found it yet. not that it matters for setting up car audio. Note that this software will need the free 3.01 upgrade for it to work with the M-Audio Transit sound card
> 
> The website is here for those interested:
> www.wavecapture.com
> 
> Its still early, but IMO this software is awesome. free, nice looking, intuitive, very easy to use. i esp like the spectrum analyser/RTA functions built in as well. Programs like speakerworkshop only use MLS and nothing else....
> 
> great recommendation!!


Distortion measurement is one of those numbered buttons at the top.... but yes it's a great program!


----------



## blackreplica

Yep you're right i found it!

For the benefit of those interested:

Some limitations with the software:
1 MLS measurements in a maximum of 1/3 octave steps(more would have been nice)
2 Enclosure simulator not allowed
3 Clipboard functions(copy, paste) not allowed. So you cant merge charts i think, but you can still line up impulse measurements next to each other in seperate graphs if doing time correction
4 Limited crossover simulation capability

Those are what i've been able to find up till now. 

Cheap, with winMLS, how do you change the number of sampling points in winMLS(eg, 3 points per octave, 6 points, 12 points per octave etc)? I dont see the setting anywhere?


----------



## npdang

blackreplica said:


> Yep you're right i found it!
> 
> For the benefit of those interested:
> 
> Some limitations with the software:
> 1 MLS measurements in a maximum of 1/3 octave steps(more would have been nice)
> 2 Enclosure simulator not allowed
> 3 Clipboard functions(copy, paste) not allowed. So you cant merge charts i think, but you can still line up impulse measurements next to each other in seperate graphs if doing time correction
> 4 Limited crossover simulation capability
> 
> Those are what i've been able to find up till now.
> 
> Cheap, with winMLS, how do you change the number of sampling points in winMLS(eg, 3 points per octave, 6 points, 12 points per octave etc)? I dont see the setting anywhere?


I'm not sure how to add more numbers at the bottom, but you can increase the measurement resolution by increasing the FFT size.


----------



## Hobbes26

Cool stuff. Hope to play with all of the software when I find some time


----------



## Hobbes26

Some more to check out?

http://sourceforge.net/projects/xlds/
http://sourceforge.net/projects/libmls0/

and

http://digilander.libero.it/hsoft


----------



## blackreplica

Great find there! Tried those out just now

The first one(FreeProbe) is very simple and easy to use. But it loses out in terms of some useful functions like merging graphs and distortion measurements as well as impedance measurements, for example. But it offers a far greater resolution for MLS measurements than the lsplab 3.1 demo version which makes this really great for a casual car audio tuner. Plus it measures all the other goodies too like spectral decay and impulse. Supremely easy to use(because there isnt much you can do except measure). 

Cant get the second one to work. No .exe! Maybe i'm missing something LOL

As for the third one, its a spectrum analyser. More advanced functionality than your average spectrum analyser software(being able to feed different signals to left and right channel simulateneously for example). But at the end of the day, its just a spectrum analyser and nothing more. good for those looking for a free RTA/spectrum analyser type software but there are so many limitations in this type of measurement so MLS is always a better option if you can find one.

So far my preferences are

1 LSP Lab 3.1 - Fantastic software, full of features, VERY easy to use BUT demo version is VERY limited in functionality. The full version, although awesome, will cost in the region of 400 USD or slightly more, which means this thing is out of reach for most, including myself, unless you are happy with the limited capability of the demo. Although its ok for now, i expect i will be hungry for greater resolution in a matter of days. 3 samples per octave for an MLS measurement is not much better than a standard RTA.

2 FreeProbe - No fancy features like LSP Lab but just as easy(if not easier) to use. And if MLS/impulse/CSD is all your after in something you dont have to pay a cent for, then this is perfect IMO.

Any more programs? I love trying them out.


----------



## npdang

Ok I see what you mean. Very limited frequency resolution, and can't adjust the plot to show under 100hz?


----------



## blackreplica

are you referring to lsp lab 3.0? I can get the thing to measure from 20Hz, but due to the low sampling rate(max 3 per octave) the results are more of a discreet range than a continous range if you know what i mean? It loses accuracy because the MLS signal is just a line drawn with 1/3 octave points as the markers. With freeprobe you get a lot more sample points and thus you get a far more detailed graph


----------



## Hobbes26

Have you tried the retired version of WinMLS (version 2)?

Can be found through the download page, at the bottom. I just noticed it, and haven't read up on what the differences are.... It's free too.


EDIT: Whoops, it's not free - demo 30 days - unless i'm missing something here...


----------



## blackreplica

Nah they all only work on 30 day evaluation unless you buy the software. I just got my evaluation key from winmls last night. Been messing about with it a short while just now. So far, i like it. Its not as easy to use as lsplab(although winmls is still reasonably easy to use) but much cheaper(full version vs full version). I think lsplab has a lot more features too but in terms of tuning car sound systems, winmls i expect should be more than enough. too bad there's no additional RTA functions like lsplab. 

Also, it seems like winmls does not measure distortion? I'll wait for cheapboy to chime in on this one since he probably knows this program a lot better than i do. I think the extra 79 dollars for winmls 2000 personal over the free demo version of lsplab is definitely worth the money. But if money was no object, i'd take the lsplab full version. More revisions to this opinion to follow once i know winmls better


----------



## npdang

blackreplica said:


> Nah they all only work on 30 day evaluation unless you buy the software. I just got my evaluation key from winmls last night. Been messing about with it a short while just now. So far, i like it. Its not as easy to use as lsplab(although winmls is still reasonably easy to use) but much cheaper(full version vs full version). I think lsplab has a lot more features too but in terms of tuning car sound systems, winmls i expect should be more than enough. too bad there's no additional RTA functions like lsplab.
> 
> Also, it seems like winmls does not measure distortion? I'll wait for cheapboy to chime in on this one since he probably knows this program a lot better than i do. I think the extra 79 dollars for winmls 2000 personal over the free demo version of lsplab is definitely worth the money. But if money was no object, i'd take the lsplab full version. More revisions to this opinion to follow once i know winmls better


I know it really sucks... I like lsplab why can't they just make it a bit more reasonably priced 

Winmls does measure distortion. You would just set it to triggered measurement or sine, and then play a sine wave or burst tone. Then look at the frequency response. If you read the tutorial on how to interpret a distortion plot it will tell you all you need to know from there.

However, it doesn't do a swept sine type of distortion measurement.... where basically it sweeps a bunch of sine waves from x frequency to y frequency... and then plots the thd underneath the frequency response. With winmls you're stuck looking/testing 1 frequency at a time.


----------



## Hobbes26

http://www.etfacoustic.com/

There's also a program called SoundEasy.. sold at PartsExpress (has it been mentioned yet?) 

And then there's LspCAD, which comes with a separate program called JustMLS (free with purchase of LspCAD) which does simple MLS measurements ONLY. I don't think it does distortion measurement/analysis.


This is becoming a nice compendium of measurement programs 


Blackreplica, what equipment are you using for measurement?


----------



## blackreplica

Soundeasy looks interesting, esp since john from www.zaphaudio.com uses it, and i like his graphs, but its pretty expensive(200+ at partsexpress) and some guys from the diyaudio forums have said that its not particularly easy to use so i knocked that one off from my list. According to John, lspcad is not as functional as soundeasy and not easy to use at all so i didnt consider that one either.

hardware wise, i'm waiting on the mic/preamp combo i ordered from that (german?) website where cheap got his mic/preamp. In the meantime i just mess with the softwares by taking measurements with my sound card output connected to my laptop soundcard mic input. I'm trying to score a cheap m-audio usb transit right now, waiting for a good deal to come up on fleabay. once i've got the mic/preamp/soundcard, i'll be aiming to make a decision on which software to go for. I still like lsplab best, wish it wasnt so damn expensive!


----------



## blackreplica

npdang said:


> blackreplica said:
> 
> 
> 
> Nah they all only work on 30 day evaluation unless you buy the software. I just got my evaluation key from winmls last night. Been messing about with it a short while just now. So far, i like it. Its not as easy to use as lsplab(although winmls is still reasonably easy to use) but much cheaper(full version vs full version). I think lsplab has a lot more features too but in terms of tuning car sound systems, winmls i expect should be more than enough. too bad there's no additional RTA functions like lsplab.
> 
> Also, it seems like winmls does not measure distortion? I'll wait for cheapboy to chime in on this one since he probably knows this program a lot better than i do. I think the extra 79 dollars for winmls 2000 personal over the free demo version of lsplab is definitely worth the money. But if money was no object, i'd take the lsplab full version. More revisions to this opinion to follow once i know winmls better
> 
> 
> 
> I know it really sucks... I like lsplab why can't they just make it a bit more reasonably priced
> 
> Winmls does measure distortion. You would just set it to triggered measurement or sine, and then play a sine wave or burst tone. Then look at the frequency response. If you read the tutorial on how to interpret a distortion plot it will tell you all you need to know from there.
> 
> However, it doesn't do a swept sine type of distortion measurement.... where basically it sweeps a bunch of sine waves from x frequency to y frequency... and then plots the thd underneath the frequency response. With winmls you're stuck looking/testing 1 frequency at a time.
Click to expand...

Damn....i really like how lsplab measures distortion, its across the frequency spectrum just like john krutke's graphs. Too bad winmls only does it at a specific frequency


----------



## blackreplica

since this thread is compiling data on measurement programs here's the link to that diyaudio thread i was talking about which compared lspcad to soundeasy. pay special attention to zaph's(John Krutke) comments, he knows his stuff! I love his website!

http://www.diyaudio.com/forums/showthread.php?s=&threadid=22804&highlight=

"Hey, this old thread is back? Cool. 

Right off the top of my head, I can think of about 50 things SE can do that LspCAD can't. On the other hand, it's hard to list even a few things LspCAD can do that SE can't.

For my puposes, LspCAD would be completely useless without at least purchasing an expensive measurement package like Praxis to make up for the missing functionality. Can the new version of LspCAD even measure T/S parameters yet? JustMLS is nothing more than just MLS. (good name for it I guess) But SE's EasyLab is a comprehensive suite of testing and measurement apps.

I think newbies are going to have a hard time with either program. Neither is particularly easy to use. Even more so now that LspCAD recently copied the way SE handles schematic construction.

As far as modeling and optimizing crossovers, that is the easy part of these programs and they all do it equally well, including Speaker Workshop."


----------



## npdang

I actually own soundeasy. ALthough it is very comprehensive and well priced, 2 things annoy me. It requires a fob plugged into your computer to work. That's REALLY annoying especially when you can't find your fob 

Also, the interface sucks Imo. It's straightforward and easy to use, but the windows are just god aweful. You can't really separate the measurement settings from the output display... so alot of your screen real estate is being used up and it's hard to see your plots. Also, there's very few options for changing colors, overlaying and splicing plots, basically changing the format/scale/colors of your measurement plots etc. easily.

In any case I always buy from Partsexpress. You can demo the software for $30, and if for any reason you don't like it you got a full refund.


----------



## Eastcoast

*MLS*

Whats the advantage to using these MLS, LMS, PMS whatever measuring systems?? As opposed to an RTA? Laymens terms if you will. I've always used RTA and found it useful, but I'm ready for the next step...


----------



## npdang

Well, with rta all you can do is measure frequency response in 1/3 octave bands. 

With "MLS" type measurements, you play a test signal for a few seconds, then the program records what is called the "impulse response". From the impulse response you can then generate tons of info, the least of which is frequency response. You can also look at phase, time arrival, frequency over time, frequency response minus reflections, etc.


----------



## FaintReality

> *D.* Last but not least, you will need cables to wire this whole thing up.
> 
> -	A cable to connect the mic to the mic pre-amp
> -	A cable to connect the mic pre-amp to your soundcard input
> -	A cable to connect the soundcard output to your amplifier/processor (not required if you’re using an RTA and test cd w/pink noise)
> -	A mic stand to hold your mic while taking measurements (optional)[/i]



If I were to go with the M-Audio Transit sound card and Audio Buddy mic pre-amp, along with the Behringer ECM8000 mic, what all cables will I need. 

mic to pre-amp: mic = XLR (assuming male output on mic?) to pre-amp = XLR (female input on pre-amp)

mic pre-amp to soundcard: pre-amp = 1/4" out to soundcards 1/8" input?

soundcards out to processor: soundcards 1/8" out to Behringer DCX2496 XLR (female input on processor) 

Is the above all correct? My girl is buying me the above (excluding processor) for my b-day on the 24th, so I need to let her know what exactly to order to arrive in time 

Thanks, Dave


----------



## npdang

That sounds about right to me... may want to double check on M-audio's site to make sure all the cables are correct.


----------



## 87DXHatch

Will Windows 98SE be good enough to run these programs and the equipment? I might be getting an older laptop for really cheap, so Win98SE might be the only thing that runs decently on it.


----------



## LoudSounds

This is probably a dumb question but why do you need a preamp for the mic? Is the mic input on the sound card not good enough? Would a decent dj mixer be an adequate preamp for the mic or will that not work?


----------



## npdang

Most measurement mic's won't get enough power from the soundcard mic input.

You can certainly use any preamp you want, however you'd want to make sure that it doesn't distort your measurements.


----------



## FaintReality

With WinMLS 2000, how do I use or find the oscilloscope feature so that I can set the gain controls on the amps while being able to view the clipped / un-clipped signal? I can't seem to find this function, nor can I find anything in the help files...

Thanks, Dave


----------



## npdang

FaintReality said:


> With WinMLS 2000, how do I use or find the oscilloscope feature so that I can set the gain controls on the amps while being able to view the clipped / un-clipped signal? I can't seem to find this function, nor can I find anything in the help files...
> 
> Thanks, Dave


Sorry for the late reply. Better to set your gains by ear Imho.

If you want to use scope look up at the top menu there should be a box that says "MLS" in it with a drop down arrow next to it. Change that to "triggered, no excitation (scope) ". Then just click on the "GO" button when you're ready to begin. Also make sure one of your measurement windows is set to "time data".


----------



## FaintReality

npdang said:


> FaintReality said:
> 
> 
> 
> With WinMLS 2000, how do I use or find the oscilloscope feature so that I can set the gain controls on the amps while being able to view the clipped / un-clipped signal? I can't seem to find this function, nor can I find anything in the help files...
> 
> Thanks, Dave
> 
> 
> 
> Sorry for the late reply. Better to set your gains by ear Imho.
> 
> If you want to use scope look up at the top menu there should be a box that says "MLS" in it with a drop down arrow next to it. Change that to "triggered, no excitation (scope) ". Then just click on the "GO" button when you're ready to begin. Also make sure one of your measurement windows is set to "time data".
Click to expand...


I will have to play around with it, thanks.

As for setting by ear, do you have any recomendations for those of us that don't have golden ears? I have had one guy tell me about a radio shack driver that I can purchase for testing, in which it will work full range, and rumbles or something with the signal is clipped? I will have to dig up the email and re-read it. I usually set with a MM, then tweak to my likings from there.

Thanks, Dave


----------



## newtitan

Hey npdang

do you know if any of the m-audio pci cards can be used to for this purpose

Im thinking of buying a laptop so it would be cool to get it all setup for my car audio measurements also

thx

=============


nevermind figured it out

this one looks like it will work with the analog breakout wire attachment

http://www.m-audio.com/products/en_us/Delta1010LT-main.html


----------



## vibrator

newtitan said:


> Hey npdang
> 
> do you know if any of the m-audio pci cards can be used to for this purpose
> 
> Im thinking of buying a laptop so it would be cool to get it all setup for my car audio measurements also
> 
> thx
> 
> =============
> 
> 
> nevermind figured it out
> 
> this one looks like it will work with the analog breakout wire attachment
> 
> http://www.m-audio.com/products/en_us/Delta1010LT-main.html


uhh, maybe I'm missing something here but you cant use a PCI card in a laptop.


----------



## newtitan

lol I was assuming maudio had a laptop sound card also 

guess not after research

also do you need a 2496?( ie processor) to take the measurments?


----------



## npdang

No you don't need any kind of dsp to take measurements...

I recommend getting a usb sound card if you want a nice soundcard for your laptop at not much money. Otherwise, you could buy one of those nice digigram pcmcia cards...


----------



## Greg200SE-R

Thank you guys for inspiring me to build a laptop-based MLS system and posting my very first message on DIY right here! 

I'm in the process of trying out the different apps mentioned in this thread and have a question: How useful are the phase measurements in lspLab? WinMLS is the other app I'm looking at, but it is missing the phase portion. Should I worry about having this feature or not?

Also, I'm trying to import 2 seperate versions of the Behringer ECM8000 mic correction file (obtained from other MLS demos) into WinMLS but it is not accepting them. The text in the files themselves seem to be listed the same way, just a matter of changing file extensions... but no dice. Has anyone done this? 

I'm liking both lspLab and WinMLS but if it comes down to upgrading to full versions WinMLS will be it... but I'd like to know I'm not missing important features like the ECM8000 correction file or phase measurements if they are useful. Thanks for your input, guys.


----------



## npdang

Always great to see other people building a measurement setup! 

I wouldn't worry about phase, as it's not all that important.

Haven't used Winmls in a long time, but I think LSPlab was the better program from a feature and interface perspective. I also forgot how to import the mic cal. file. Have you checked what the manual says?

Forgot to mention Sample Champion is pretty affordable and feature rich as well. It's also very straightforward, and you can get quick support if needed.


----------



## Kramerica

I just bought a Radio Shack Digital meter and found this free program to give me a frequncy response. I have used it to find the frequency response of all the speakers in my home theater system and it seems to work pretty well.

How would I do the same thing for my car? Would I have to take out my head unit and have the signal from the computer go to the head unit, or is there away to play a cd of test tones?


----------



## Grand Masta

Nguyen,

I am about to order a Behringer ecm8000 mic, probably on Ebay so I can save some money. But do you know of a mic pre-amp that's a bit cheaper than the M-audio Audio Buddy? It seems a little pricey even at Ebay prices. Or is that the cheapest reliable unit that you know of?

Also, did you guys ever come to an agreement on what's the best software to use for tuning a system in-car as described by your other DIY thread?

Thanks.


----------



## npdang

There are a few on www.samedaymusic.com for ~$50. Should work decently, but try to avoid any that have "processing" built in.

As for software, speakerworkshop is free


----------



## dennisp

Nevermind. I figured it out.


----------



## npdang

Post your question in general forum first


----------



## dennisp

npdang said:


> Post your question in general forum first


nevermind, I figured mostly everything out for now.


----------



## Ludemandan

About microphones, would a cheaper eBay one really srcrew up the readings? I'm a college student interested in taking FR measurements on the cheap. I need to equalize my system but I just don't trust my ear to do the work.


----------



## npdang

You would need a mic with a relatively flat sensitivity. Something cheap like the Behringer ecm8000 works well, or there's many diy mic's out there that are quite good and can be built for cheap.


----------



## sigma6

Hey guys, new boy here. Not to show off or anything, but check out the toys I get to play with at work: http://www.iotech.com/catalog/daq/ezanalyst.html

4-ch Zonicbook analyzer, mic, accelerometer and this nice software package as well. I also have a certified anechoic chamber to play with. 

There has to be _some_ upside to wage-slavery, right? 


I'm waiting on some new hardware for my install before I try this out in the car. Just curious if anyone here has any hands-on with gear like this. We bought it for the boring and mundane task of certifying gear drive systems to industrial standards, and so far that's all I've had chance to do with it.

Oh and before you ask, it wasn't cheap. Not by any stretch of the imagination.


----------



## Finleyville

sigma6 said:


> I also have a certified anechoic chamber to play with.



I am sure the members of this forum (read: me!) would love to see pics of that chamber.


----------



## sigma6

One of my keys jammed in the door to show how thick it is. All the walls are the same.








One of the inside of the chamber. You can see the port that I pull all my wires through to power whatever is in there, and a test item on the small table. Microphone is on a tripod in the opposite corner, 1m away.


----------



## drocpsu

Just so you guys know, I found a post on avsforum where a guy made a room RTA/EQ'ing program that outputs sweeps and tones and whatnot. It may be useful to you, and its free. 

http://www.avsforum.com/avs-vb/showthread.php?t=529224


----------



## Ludemandan

sigma6 said:


>


Mind if I sleep in there? :blush:


----------



## sigma6

I shut myself in there once to see what it was like. Pretty weird with the quiet and total lack of echoes... kinda like a sonic black hole, every sound you make just disappears immediately, like perfect transient response. Oh yeah, it's set up with a refridgerator type light... you shut the door and the light goes off. I'm not afraid of the dark or anything, but I don't know if I could sleep in that box.


----------



## Daishi

Anybody know of any programs for RTA or MLS for OS X? I have absolutley no access to a PC based laptop so I'm limited to my iBook. The only one I've been able to find is this one.

http://www.channld.com/mts.html

Here's the ordering page for it, but I'm not sure which options are really worthwhile for an intro to doing this yourself. 

Order Page 

I've never done any tuning before on my older systems. This will be my very first total DIY deal and I'm running active for my front stage so I figure I better get some of this stuff to help me along.

Any help would be great if someone knows of a better program that won't break the bank.


----------



## jtholley03

I have looked at that but have never taken the plunge so I can't say. Looks good from what they show.


----------



## chuyler1

> Anybody know of any programs for RTA or MLS for OS X?


Take a look at the link that was posted above. The software is Java based and will run on Mac.



drocpsu said:


> Just so you guys know, I found a post on avsforum where a guy made a room RTA/EQ'ing program that outputs sweeps and tones and whatnot. It may be useful to you, and its free.
> 
> http://www.avsforum.com/avs-vb/showthread.php?t=529224


----------



## Daishi

chuyler1 said:


> Take a look at the link that was posted above. The software is Java based and will run on Mac.


Very cool. I'll have to give that a shot. 

I might also snag that Mac program as well as a trial for Mac users.


----------



## audionutz

THis tutorial is great! 
I am in the process of setting up a dedicated tuning computer and was going to use wavecapture....my question is> I was messing with the demo and I can not seem to find impulse response measurements. I need to measure arrival times moreso than any other parameter....would I be better off using another proggie, OR, and I just a dumbass and am not looking in the right area of Wavecapture?

Thanks guys!


----------



## npdang

Hey welcome to the forum Audionutz 

The impulse response should be at the bottom of the EQ-CAPTURE screen. Click the tab that says capture.

You should be careful to make sure that the time delay between measurement and recording is the same for every sample. You can check that with a quick loopback measurement. Once you know that, you can subtract the sound card delay from your measurements.

I think Wavecapture looks very promising. Spatial averaging and an auto-eq feature make tuning in-car much easier. I will definitely have to look into it.


----------



## audionutz

Killer! Thanks for the quick response! I am D/L'ing the full version of wavecapture in moments..just set up the m-audio MobilePre and made a roll-around (semi-portable) 'puter setup with printer and all for this endeavor.


----------



## audionutz

Well, got it all hooked up and installed and whatnot...I do NOT have an ECM8000 mic, but, I am using the standard rta mic from my audio control meter and it seems to work..
BUT, the problem is I am not seeing actual measurements registering on the screens. In other words, I dont think this mic is working, or the mobilepre is NOT receiving the mic input, even though i DO hear the mic sounds thru the puter speakers. THe proggy is putting out the white noise, the pulses, the pink noise, etc thru the audio outputs like it should...it just seems like I cant measure anything. Doesnt this seem strange???


----------



## solacedagony

Assuming you're using Windows:
Double click on the speaker in your taskbar. Click Options->Properties. Hit Recording and hit OK. Then hit the checkbox under which interface you're using (Probably Line in or microphone). Also, make sure the program is set to input through the correct interface.


----------



## audionutz

Yup, W-XP. At first I was thinking the demo version just was to play with, not actually use, and that I had to buy the complete version (BTW, it is well over $200!). I will try it tonight and post results


----------



## npdang

It could be the mobilepre is not supplying the correct power or pinout to the AC mic? Or maybe you don't have phantom power turned on?

Have you been able to get the mic to work with windows sound recorder?


----------



## audionutz

will check win sound recorder in a few minutes, didnt think of that


----------



## audionutz

YES, sound recorder works.


----------



## npdang

I'm not familiar with that program, but I would check to see that you are selecting the right input? I'd even try them all until one worked... sometimes they name them weird things.

Can you post a screenshot of the config and/or main measurement screen?


----------



## audionutz

i would but it is not on this 'puter, so no net access 

FOund one thing out of whack, under levels, where the input and output levels are set and the calibration is supposed to take place, the dropdown screen under "input" shows only the selection "none available"! this is bad, right? Is this why the proggie doesnt seem to be recognizing the mic/recorded sound?


----------



## audionutz

FOUND IT!!!!!!!! Mobilepre screen shows that the "USB Record" setting keeps going back to "mute" each time I do anything with Lsplab...tried to find setting and whatnot to change, but nothing! Like I can open the freq resp screen in lsplab, open mobilepre screen, un-mute the USB record button, see the actual freq response (a good thingYAY!), but as soon as I close a window or select another parameter to mess with, the mobilepre is in "mute" again....WHY? HELP!


----------



## audionutz

OK there is a setting i have to select under the advanced settings of Lsplab titled "dont mute inputs on soundcard" and it works. Cool, but impulse response seems to be exceptionally hard to decipher compared to the screenshots of the winmls proggie. Am I doing something wrong?


----------



## npdang

First, look at the frequency response... does it look "ok" ? If not it's possible you're just picking up noise.


----------



## audionutz

FReq res looks OK, but how would I know if I was doing something wrong?


----------



## ghart999

npdang - you mentioned in the first page of this tutorial that I need a full duplex soundcard. If I can play and record at the same time, can I be sure I have full duplex? I have an older IBM thinkpad so I would like to use the soundcard if I can.


----------



## npdang

You should be fine. Lack of a line input may be an issue.


----------



## solacedagony

The act of playing and recording at the same IS full duplex, I believe. Even if you didn't have a full duplex card, these days you can easily get a quick USB plug for input/output capability.


----------



## z_accoustics

I have an EDIROL UA-5 Sound interface with 48v phantom power, is that the same thing as a pre-amp? I have the ECM mic.


----------



## solacedagony

I only found the UA-25 on Roland's website, but yes, that is a preamp.


----------



## 03blueSI

Just thought I would mention for mac people. Fuzzmeasure is the way to go for log and MLS measurement. It will allow you to take multiple samples to reduce the measured noise and increase S/N ratio when measuring. It is also real easy to use.


----------



## Rivers

Folks, I've gone through the whole thread and its been quite amazing  Having said that I am trying to find a easy to use program that will allow me to:

1. choose what the best x-over settings are
2. set time alignment
3. EQ

Can someone recommend me what program would probably do this and with a very easy to use GUI? I tried TrueRTA and its fairly easy to use but dont believe x-over and TA settings can be done with the program?

Thanks.


----------



## npdang

One of our old members had great sucess using this program:

http://soundhobby.com/measurementsystem.htm

Again, I would recommend reading the speakerworkshop manual (google for it) to get a good idea of what's involved in taking measurements and corellating that back to subjective impressions. You can always skip the parts about loudspeaker design.


----------



## npdang

I also wanted to add that many soundcards have a varying delay between the start of playback and the recording. This will mess with your initial time arrival measurements. Some software such as MLS allow you to correct for this by connecting one channel (left or right side) back to the input of your soundcard directly, so that the delay can be measured and corrected for with each measurement. If your soundcard has a fixed delay, such as the USB transit, you can simply measure that delay with a loopback cable and subtract it from all your measurements.

If you have some money to spend, a full hardware/software package such as CLIO or Praxis is very nice as well since the software is generally already calibrated for your hardware, and you don't have to worry about compatibility or hidden issues.


----------



## hc_TK

i've got realy big problems finding a desent free RTA with good messuring resolution, or a cheap simple program. The ones i've tried is either to hard for me to use, a 30 day trial or with crappy messurement resolution..
Can anyone help me? i've got everything else i need, behringer mic, and all the hardware. 

Thanks


----------



## ludlamtheory

so lets say im not quite interested in stuff like impulse response, and all this stuff, and just want a plain pc based rta to run off my laptop. all i've got is a mic input, should i still look into a preamp/usb sound card for good accuracy? or will a preamp alone do me fine?


----------



## hc_TK

ludlamtheory said:


> so lets say im not quite interested in stuff like impulse response, and all this stuff, and just want a plain pc based rta to run off my laptop. all i've got is a mic input, should i still look into a preamp/usb sound card for good accuracy? or will a preamp alone do me fine?


i bought an usb plug in preamp, the one mention on the first page. the mobilepre..This unit works great!


----------



## chuyler1

You will need something like the Mobilpre if you want to connect a half-way decent microphone.  Any 1/8" jack microphone that you plug into your laptop is not going to give you an accurate reading of your system. You'd be lucky if such a microphone picked up anything at a distance of more than 1 foot.


----------



## ludlamtheory

meh, so buying from someone reliable like pssl (prosound and stage lighting), this is gonna be 200 in just hardware...
are there any free rta programs out there?


----------



## hc_TK

ludlamtheory said:


> meh, so buying from someone reliable like pssl (prosound and stage lighting), this is gonna be 200 in just hardware...
> are there any free rta programs out there?


Yes, but i havent found any of them i tried to be accurate enough. I tried som 30day trials that have worked good, but 30 days sucks.
The only one i fell comfortable with is visual analyser,but i dont fell like this is accurate enough either. Im still looking.


----------



## bojo

Okay a few questions.

I just want to do a simple RTA to have a look at how my car is sounding. Eg just looking at whether the crossovers are smooth, and whether that tweeter needs to be louder etc.

My pc's got a mic in, and i've got a couple of mics to play with, i don't really need a preamp if i use my mic port do i?, it should have its own little preamp working in there.

Also i figure it won't be the best results, but what's a program that would let me do a RTA test?. All of those talk about mls stuff, and speakerworshop doesn't run on my pc (installer won't run at all). Granted the site says its from 2002.


----------



## Whiterabbit

not accurate at all. not even close.

But thats OK too. the value of the "budget" (read: free) PC measuring systems with grossly innacurate mics isnt absolute measurements, its relative.

Very effective in getting your FR even on both sides, or your phase even on both sides measured from the drivers seat.

and VERY effective to set your T/A ballpark values from the drivers seat.


----------



## z_accoustics

What's the most enconomic way to get oscilloscope functionality? I would think you could get a cheaper solution by using existing pc hardware than going out and buying a stand alone oscillascope. 

Someone have a suggestion on this? I'd like to measure the wave put out by my sub amplifier (1000watts).


----------



## MarkZ

Really, the best way is to use an oscilloscope. They're not that much money if you buy an older one. Affordable PC measurement systems are typically soundcard-based, and you have a limitation on just how many volts you can provide to them. 1000 watts, no way. You'd have to step down the voltage with a voltage divider if you wanted to use a PC measurement system. A voltage divider will only cost you about $1 to construct, but you'll have to do some math to figure out the actual voltage amplitude you're measuring. An o-scope will tell you right then and there what the amplitude of the wave is.


----------



## abergdc

*How to set up for MLS with H701*

Great threat. But I'm like a couple of others: tempted to just use TrueRTA and a pink noise CD to get FR. I figure this will help check xover frequencies and EQ. I can do TA by figuring distances and doing a bit of algebra. Make sense?

The other thing: it was mentioned early on that the complication with the MLS approach is the need to feed the impulse through the system. Indeed, I don't quite get how to do that. If I have an Alpine H701, can I go from the sound card to the line-in of the H701? Seems pretty complicated . . .

Thanks,

Andy


----------



## npdang

*Re: How to set up for MLS with H701*

It's pretty simple, just connect the line output of the soundcard to the line in of your h701.

The issue with RTA is sometimes poor noise immunity, and a fixed measurement window of 300ms.


----------



## z_accoustics

I am unsure if my sub box is overdamped (aka undersized/inappropriate Qtc). Is there some way that this mic/computer/software setup can help diagnose what is sounding off about my subs? What analysis should I run and what should I look for in the analysis to identify causes such as overdamping and distortion from the sub drivers?

P.S. thanks markz, i'll just procure an o-scope somehow.


----------



## npdang

Easiest way is to set the mic close up to the driver's cone, (as if a sheet of paper were laid across the cone), and take a frequency response measurement. You can calculate the qtc of the driver from that. Or, you could measure the impedance of the driver in the enclosure and extract the t/s parameters.


----------



## z_accoustics

npdang said:


> Easiest way is to set the mic close up to the driver's cone, (as if a sheet of paper were laid across the cone), and take a frequency response measurement. You can calculate the qtc of the driver from that. Or, you could measure the impedance of the driver in the enclosure and extract the t/s parameters.


Thanks! Please elaborate on how I calculate Qtc from the close mic frequency response.


----------



## jmelan

I was looking around at the different software packages mentioned in this thread and I wanted to know if anyone is using the one mentioned as being from avsforum:

Room EQ Wizard

since it is FREE, i was going to try it out; but i really don't know enough to see if the specs are good for use in car audio calibration.

here are what i would think is the relevant info:

"Signal Generator offers sine waves, square waves, linear and logarithmic sine sweeps and pink noise (full range, speaker calibration, sub calibration and custom filtered"

"*Frequency response measured using logarithmically swept sine signals *for fast, accurate measurements with approx *0.36Hz resolution *across the measured range."

"*Impulse response is derived from the measurement*, allowing spectral decay plots, waterfalls and energy-time curves to be generated. Impulse responses can be exported to and imported from WAV files with 16, 24 or 32-bit resolution."

Most people on avsforum and hometheatershack seem to use it to automatically detect peaks and calibrate the Behringer Feedback Destroyer Pro for their sub. There is some mention of adding this functionality to the DEQ2496 in the near future as well.

There seems to be a good number of options for the graphs, in terms of overlay of multiple graphs, averaging, etc. 

The online tutorial seems to be very straightforward and walks you through each step in setup and measurement. 

There are professional calibration files available for the ECM8000 to give a flat response over a large range as well.

Anyway, let me know what you think!! I wanted to measure the frequency response in my car as i finish my installation to see what improvements are made along the way

Thanks


----------



## harrier

Thanks for the link.
I'm gonna try it out too.


----------



## jmelan

i didn't realize at first, but when you try it out, the measurements at .36Hz resolution can give a rough response at higher frequencies. I thought something was wrong.

The program has smoothing options at 1/24, 1/12, 1/6, 1/3, 1/2, and 1 octave that will give you more to work with in terms of getting a detailed picture of your frequency response.


----------



## Amish

I had asked over at htguide whether Room EQ Wizard could be used to set up active crossovers. Ends up that response up high is fairly inaccurate and I was recommended to use other programs. Seems good for subs, bad for mids/highs. I'd love to have someone prove this wrong though!

I'm in the process of trying to iron on some wrinkles in my Ai-Net to RCA adaptor so I can use this to help with sub integration and measure car transfer functions.

It's easy to use, repeatable and the EQ function works amazingly well, at least with regards to the BFD.


----------



## hc_TK

I got room eq wizard also, but i havent tried it out. I also got another very easy free program called AudioTester. I dondt remember where i downloaded it but if somebody got a server, i can upload it. (i think i found the link at diyforum.som. good luck try find it.)
I would be great if someone (ndang? ) could run a test on a few free programs to check if they are any good.


----------



## jmelan

ok, well maybe someone could take a look at this graph (Room EQ Wizard:the graphs are smoothed at 1/3 octave) and let me know how it looks. my best guess is that, for the mid/tweeter measurement, above 2kHz, things start to get a little rough, as mentioned above:


Amish said:


> I had asked over at htguide whether Room EQ Wizard could be used to set up active crossovers. Ends up that response up high is fairly inaccurate and I was recommended to use other programs. Seems good for subs, bad for mids/highs. I'd love to have someone prove this wrong though!


As expected, the sub response looks clean? and the PEQ settings behaved as modeled in the program.

the impulse response is useless for T/A, as it just assigns the initial peak to time 0.

i used the alpine kca-121b ai-net/rca adapter through a cda-9830 for measurements (w/ ECM8000 and mobilepre)

i also tried using freeprobe, but my results were less consistent and i couldn't figure out any way to configure the program.

since this is a tutorial thread, please let me know if this does not belong here or feel free to delete it.










the sub crossover is 80Hz at 12db on a mrv-f345, mid/tweeter HP at 200 Hz (vifa mg10/seas neo)

i don't have a second amp yet, so the midbass (rs180-4) is not connected.


----------



## npdang

Is there an option so that the initial time arrival isn't normalized to 0?

Looks as if your sub is dropping rather sharply at 50hz. You may want to try re-orienting it or changing the lowpass. The tweeter looks fine Imho, although the midrange looks very rough given the 8db scale.


----------



## jmelan

thanks for taking a look npdang 

no, there is no option for time arrival not to be normalized to 0 

someone asked the author about it, so it may be implemented in a future release. behringer is sending him a deq2496 - so maybe when he optimizes the program for that. so far, the main purpose has been for sub calibration.

the sub is kind of fixed in place, so repositioning is not an option 



i am currently looking at another free option and will post a comparison if it is good. some info on avsforum has been very helpful.

i would have tried winMLS by now, but they sent me an invalid activation code for the 30 day trial.


----------



## npdang

Can you change the measurement window length? I'd use a much shorter window for the tweeter... perhaps < 5ms, and a longer one for the sub perhaps up to half a second or a full second even.

With subs, I like to take the approach of only eq'ing large sections... in other words very wide q's and no more than 2 bands. I find using more tends to make the bass sound worse subjectively than the plots would reveal.


----------



## bdubs767

npdang,

how do you go about using the O-scope on the 
http://www.winmls.com
program?

Do you need any other devices to run it the O-scope?


----------



## hc_TK

jmelan said:


> ok, well maybe someone could take a look at this graph (Room EQ Wizard:the graphs are smoothed at 1/3 octave) and let me know how it looks. my best guess is that, for the mid/tweeter measurement, above 2kHz, things start to get a little rough, as mentioned above:
> 
> 
> As expected, the sub response looks clean? and the PEQ settings behaved as modeled in the program.
> 
> the impulse response is useless for T/A, as it just assigns the initial peak to time 0.
> 
> i used the alpine kca-121b ai-net/rca adapter through a cda-9830 for measurements (w/ ECM8000 and mobilepre)
> 
> i also tried using freeprobe, but my results were less consistent and i couldn't figure out any way to configure the program.
> 
> since this is a tutorial thread, please let me know if this does not belong here or feel free to delete it.
> 
> the sub crossover is 80Hz at 12db on a mrv-f345, mid/tweeter HP at 200 Hz (vifa mg10/seas neo)
> 
> i don't have a second amp yet, so the midbass (rs180-4) is not connected.


How did you get the roomeq to messure that accurate over 200hz? Ive tried but im just getting a damn straight line over 200hz..(you wish  )


----------



## jmelan

i think the default settings in Room EQ wizard are only set to measure to 200 Hz. 

In the "measure box", click on the drop down arrow and change the "End Freq" of the signal that is generated. Put whatever you want there.


----------



## jmelan

npdang said:


> Can you change the measurement window length? I'd use a much shorter window for the tweeter... perhaps < 5ms, and a longer one for the sub perhaps up to half a second or a full second even.
> ...


Yes you can change the window length in Room EQ wizard, but it didn't seem to smooth out the high end measurements. so i tried a different way to compare.

Here are the results i got with another approach using a combination of a few free software programs available. (info on all at DuffRoomCorrection) 

It is the same software package that was used by the guy in the "Digital room correction - in a car" thread

All use command line interfaces and text files for adjustment, so they are not the most user friendly. It took a couple of hours for me to figure out the details for each.

First, i used the "Simple Automated IR Measuring Tool" . It generates a sine log sweep, plays and records the results, allowing use of a loopback cable for soundcard compensation, and gives you the impulse response file.

Next, I used tools available with the Digital Room Correction Program (documentation for DRC here). 

i used the scripts for "octave" packaged with DRC to generate all the graphs - about *60* of them (as encapsulated postscipt files), and then used the packaged latex document to make the html page.

click on the 1/3 octave result below to see all the graphs. The graphs show a comparison of my right channel before and after a test correction with the DRC filters. There are graphs of every possible combination it seems.

The BIG disadvantage with this approach is that you don't see your results until later.


----------



## DigitalCorrect

Great to see that you got DRC working, and that your initial results look good. How does it sound? Adobe Audition, which was originally named CoolEdit, is an especially useful tool. You can still download a free 30-day trial of CoolEdit. Also, MatLab is much easier to use than Octave. You can probably improve that dip at 150Hz by increasing the amount of correction applied to the lower frequencies by increasing the 4 LowerWindow parameters (MP, EP, ISPE, and RT). The dip at 1200Hz might be trickier to correct without generating noticeable pre-echo. The phase also shows good improvement. In my experience, that critical area around 1kHz to 3kHz is difficult to correct in automobiles.


----------



## jmelan

thanks for taking a look  - i guess i forgot to mention about the midbass here. i have the sub LP at 80 and the mids HP at 200, so i changed the target curve to accommodate the current setup 

at 1200 Hz, i guess that is just the effect of the car, the other channel has a similar dip at 800 or so.

i am waiting on another amp to come in for the final setup. this was a test run to make sure i could get decent results. it took some time to get used to - but i customized a script(.bat) to generated the filters pretty quickly and now it only takes 5 minutes.

i used the optimized.drc file as you suggested before.

it sounds great with a small test run using my laptop to play the filters. i am going to wait until i have everything finalized to convert the lossless music files for use with my ipod.

Left channel results here


----------



## DigitalCorrect

I would try to fix that big dip around 100Hz in your uncorrected system rather than trying to get DRC to correct it. Otherwise, DRC will be boosting your gain in this area by 12db to compensate and you will not be happy with the results. Also, the left channel high frequencies are rolling off too early - almost like something is blocking the tweeter or the mic is very off-axis. You will also need to introduce some delay into the left channel.


----------



## jmelan

DigitalCorrect said:


> I would try to fix that big dip around 100Hz in your uncorrected system rather than trying to get DRC to correct it. Otherwise, DRC will be boosting your gain in this area by 12db to compensate and you will not be happy with the results. Also, the left channel high frequencies are rolling off too early - almost like something is blocking the tweeter or the mic is very off-axis. You will also need to introduce some delay into the left channel.


thanks,

i was hesitant to put too much effort into getting things perfect before i got a second amp installed.

now that is done, so i did several runs of the DRC program with different options and used my laptop to play each filter and compare the results of each.

i settled on using the erb.drc settings file and the bk3-spline-subultra taget file. The target file introduces a slight rolloff at high frequencies.

here is a graph with 1/3 octave smoothing applied of the right and left channels before and after correction with the optimized.drc file.

i am going to put more detailed information in my install thread here


----------



## npdang

Awesome... how do you find DRC? I was a bit disappointed with the results initially, but I didn't really give it much time.


----------



## jmelan

npdang said:


> Awesome... how do you find DRC? I was a bit disappointed with the results initially, but I didn't really give it much time.


DRC is definitely not the most user friendly program. It took me a good amount of time to figure out how to configure everything (with some advice from DigitalCorrect), but now that i have everything set up it doesn't take much time to run. 

I really think the results are great. With the DRC filters, everything sounds a little cleaner and more precise. I can hear much better instrument separation than before.

However, I just got started with car audio, so I don't really have a good basis for comparison to other processing options. 

The DRC filters definitely sound better than the equalization i tried with my CDA-9830 (3 band PEQ).

It would be great if you get a chance to post the results from a test of DRC on your system!!


----------



## DigitalCorrect

Something to watch out for: By default, DRC will use the largest spike in the impulse response as the impulse center. However, in automobiles it is easy to have a spike representing a reflection larger than the main spike. You can handle this by using the BCImpulseCenterMode and BCImpulseCenter parameters.


----------



## jmelan

DigitalCorrect said:


> Something to watch out for: By default, DRC will use the largest spike in the impulse response as the impulse center. However, in automobiles it is easy to have a spike representing a reflection larger than the main spike. You can handle this by using the BCImpulseCenterMode and BCImpulseCenter parameters.


thanks, that is an excellent point!! here i was thinking i had finally configured everything properly.

what audible effect would you expect it to have if the impulse center is detected improperly? i can't figure out how to output the DRC log file, so I checked the IRs in adobe audition 

The largest peak in the left channel was at 1850978 samples, while the initial peak is at 1850950 samples. 

On the right channel, both are at 1850994

A quick rerun of DRC showed it identified the impulse center at 1850978 and 1850994 as expected, so the left channel center is off by 28 samples.

One concern I had about using the BCImpulseCenter option is this statement in the manual:

"If channels are misaligned more than few samples this will cause errors in the correction filters, usually causing a rising frequency response, and so a bright sound."

I assume that only applies in the case of an attempt at time alignment. In my case, I should be able to specify the impulse center for the left channel at the initial peak of 1850950 ??

thanks for all the great advice in getting DRC setup properly


----------



## DigitalCorrect

The DRC procedure you mention is a way to fix small time alignment problems. We have much larger time alignment problems in automobiles, which we correct by introducing delay into the left filter. I suspect that either (a) your mic was significantly off-axis to one of your left speakers, and a reflection was stronger than the direct sound, or (b) your mic is much closer to the high frequency speaker than the low frequency speaker (or vice-versa). Either way, this is very difficult for DRC to correct. I would try setting BCImpulseCenter to the first major spike in the impulse response.


----------



## jmelan

well, the left speaker is off axis to the microphone and the sub is in the cargo area of a 4runner, so i think both (a) and (b) could apply here.

i will try to set the BCImpulseCenter option as you suggested and see if I can tell a difference. Either way, I will probably need to look at the IR for each driver as well to really confirm the results.

thanks again


----------



## jmelan

DigitalCorrect,

With BCImpulseCenterMode=M, setting the BCImpulseCenter=1850951 or 1850953 creates a corrupt output file, while setting it to 1850978 (as in auto detect mode) creates a valid filter? 

So, I don't think i can use the manual impulse center setting? Or possibly another setting needs to be changed?

***EDIT***

I found a solution to the problem. I don't know what the problem was before, but by also changing BCNormFactor=1.0 (input file normalization) i get a valid file.

The left filter before and after manual specification of the impulse center is shown below. I offset one by 2dB so they would both be visible.

It looks to me like the differences are mainly above 2500Hz


----------



## DigitalCorrect

Sometimes you can get an error message saying "log limit reached in cepstrum computation", and the filter will be all zeroes. In this case, reduce BCInitWindow to something like 125000. There is not a big difference in your two filters, but remember each tic on the graph is 6 db, which is one half (or twice) the volume. Also, you will probably see a larger difference in your phase graphs. Lastly, the largest spike is not necessarily the highest (or lowest) little square on the Adobe screen - you have to look at the sync interpretation to see the largest spike, and DRC does not do this.


----------



## jmelan

DigitalCorrect said:


> Sometimes you can get an error message saying "log limit reached in cepstrum computation", and the filter will be all zeroes. In this case, reduce BCInitWindow to something like 125000...


Wow, that is exactly what i was getting. The filter was completely blank. You seem to have more info on hand about DRC than any online resource I have found.



> Lastly, the largest spike is not necessarily the highest (or lowest) little square on the Adobe screen - you have to look at the sync interpretation to see the largest spike, and DRC does not do this.


Well, here is what i was looking at in audition. DRC in auto mode picked the sample with the red arrow; i set BCImpulseCenter to the sample with the white arrow. I am not sure how to do a sync interpretation.


----------



## DigitalCorrect

You did it correctly, and you should get better results. It's pretty easy to get a flat frequency response with DRC in a car. It's somewhat more difficult to get a flat phase response, and you should see fewer (if any) phase wraps now. The sync interpolation is shown as the lines that connect the squares in Audition, and the line defines the real signal. Sometimes the line is higher (or lower) than the squares:


----------



## ErinH

npdang said:


> -	A cable to connect the mic to the mic pre-amp
> -	A cable to connect the mic pre-amp to your soundcard input



This is where I'm confused. I'm not sure what to look for with these cables? 

I'll likely buy the Behringer ECM8000 mic & M-Audio “Audio Buddy” preamp. I’m just not sure how I get the pre-amp wired to the computer, and the microphone wired to the pre-amp? Someone care to explain this? Pictures, links, etc would be very helpful.


----------



## Thumper26

bikinpunk said:


> This is where I'm confused. I'm not sure what to look for with these cables?
> 
> I'll likely buy the Behringer ECM8000 mic & M-Audio “Audio Buddy” preamp. I’m just not sure how I get the pre-amp wired to the computer, and the microphone wired to the pre-amp? Someone care to explain this? Pictures, links, etc would be very helpful.


http://www.m-audio.com/products/en_us/AudioBuddy-focus.html

click the closeup view on the left.

run xlr cable from the mic to one of the xlr inupts.

then run a 1/4" cable from the preamp to your computer. You can get 1/4" to minijack adapters at walmart, radioshack, etc. 

i live in an apartment, so i'm just going to get a long mic cable and run it out the window to the parking spots in front of my apartment. i have a behringer eurorack mixer that i'll use to hook into my computer.

speaking of which, you can get a eurorack for a lot cheaper than that audio buddy, but you'd need an invertor to power it in the car.

http://www.birdlandmusic.net/product.php?productid=3152&src=froogle


----------



## ErinH

I actually have an inverter, but it's pretty dang loud (it's a plug in type).

I found out how to hook that stuff up shortly after posting, but that's for reminding me. I can use this to check back on.

I need to get this stuff ordered. Soon.


----------



## ErinH

Thread revival guys.

I'm going to order a mic & preamp for the laptop, however, I won't order until Friday or next week. Which means I won't be getting anything in until late next week. I already have trueRTA, but nothing else. 

In the meantime, I have a cheapo mic from wal-mart laying around and was wondering if I could use it for relative measurements. Such as t/a & level matching. I don't really trust it for EQ'ing, but it seems to set all things relative this might work. If so, this would give me something to do for the next couple days and also get prepped on how everything needs to go.

Anyone have any idea?


----------



## Lightninghoof

Is there a mic pre-amp that is less expensive than the M-audio Audio Buddy that will serve the same purpose? I found several in the $30 range but they are tube pre-amps.


----------



## ErinH

e-bay my friend.

Also, check trueaudio's site. They have an FAQ section that lists a few other pre-amps.


----------



## thazy2

The first two cables, what do they look like or called and where can i purchase them?


thanks..........


----------



## backwoods

anybody tried any of these with vista?


----------



## DonutHands

anyone know which of these is a MLS based program?

looks like praxis would be the best

what about second best?

lsplab does not appear on wavecapture's website.

sounds like speaker workshop is pretty good, but hard to use.


----------



## npdang

thazy2 said:


> The first two cables, what do they look like or called and where can i purchase them?
> 
> 
> thanks..........


Depends on the mic, pre-amp, and soundcard used.


----------



## npdang

internecine said:


> anyone know which of these is a MLS based program?
> 
> looks like praxis would be the best
> 
> what about second best?
> 
> lsplab does not appear on wavecapture's website.
> 
> sounds like speaker workshop is pretty good, but hard to use.


http://www.lsp-lab.com/

They changed it. I like lsplab, although there are alot of other choices these days. The purebits website has alot of tutorials and great support though.


----------



## handy

have you ever tried soundcard beside m-audio? alesis?


----------



## thazy2

i have purchased the behringer mic and the all in one usb m-audio mobilepre usb.


What is the actual name of the cable?


----------



## effenay

thazy2 said:


> i have purchased the behringer mic and the all in one usb m-audio mobilepre usb.


For that setup, you want a standard XLR to XLR microphone cable. One end male and the other female. Very common cable.

Example: http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=241-345


----------



## thazy2

thank you : )


now all i need to do is decide which software and rack my brain figuring out how to use it : (


----------



## thazy2

ok, i have everything except the WinMLS2004.


From all the response, im going to buy it. But what version do i need? Is it better just to get the level two or will level one be sufficient for car and home audio? I will be doing home 5.1 later on down the road.


btw, what is used to generate these sound to test the speakers? test disk? does WinMLS generate its own sound?

sorry, newbie!


----------



## npdang

Read alot, before you buy. You can also get a regular mic from www.libinst.com that will power directly off the m-audio transit, without need for pre-amp.

Get a sample license of winmls and play with it. Yes, it can generate it's own stimulus. Re-read the first post again in detail so you can get an idea of how everything works.


----------



## thazy2

For some reason, i'd mis this:

"A MLS based system can give you a FAR greater amount of information and flexibility (especially time domain info and not just frequency response), but it will require you to connect your soundcard’s line output to the input of your audio system before any crossovers, eq, or processing is used. The way it works is that the software generates the test signal, sends it out through your soundcard, and into your stereo."


what kinda cable is this? I have the behringer mic and maudio usb pre and the cable to connect the two but what type of cable is mentioned above?




BTW, i did download win2000mls and tried it on my 5yr old dell notebook. Upon launching, error message. I then trying opening it again and small window appear w/ 0 days left for evaluation. Cant seem to get past that screen. Win2004 goes to the code request screen for purchase for evaluation. I guess im going w/ 2004.
thanks. I hate putters! 


Sorry, im very slow at this...................


thanks NPdang


----------



## DonutHands

did i read this right?

this DRC program will analyze your system and come up with filters you apply to either the music itself, or to the player using a car PC?

sounds pretty excellent, depending on how well it works. except for the fact you need a car PC


----------



## npdang

You need whatever cable goes from your soundcard output, to your amplifier input. Usually this is a mini to RCA Y cable.

You also need to e-mail winmls for an evaluation license IIRC.


----------



## npdang

internecine said:


> did i read this right?
> 
> this DRC program will analyze your system and come up with filters you apply to either the music itself, or to the player using a car PC?
> 
> sounds pretty excellent, depending on how well it works. except for the fact you need a car PC


You can convolve the filter into the song itself... so you don't need any equipment to hear what it sounds like in the car... only downside is if you take it to another car, or ipod, it might sound really weird. And doing it for your whole music collection just sucks


----------



## DonutHands

car pc ftw


----------



## DonutHands

so here is somthing that i dont understand aboutthe DRC program. i know how time delay would work using a filter applied thorugh software. but how would time delay be applied to a certain speaker when you convolve filters into the music itself?


----------



## durwood

DRC doesn't correct for time alignment for individual speakers from left to right. They have to be properly time aligned for the seat position prior to doing any DRC. What DRC does do is correct the timing and phasing between all the drivers on one side and it helps it combine or look as one full range speaker essentially. At least this is my understanding. I'm still learning how it works myself.

Convolution is the theory of taking a snapshot or sample of the entire spectrum per say of what the frequency response looks like in the time domain and combines that with the filters/eqing it has figured out from your measurments. The filter never changes but the music passing through does. The result is a completely new snapshot or sample. I hope I'm explaining this right.:blush: I'm sure someone will correct me if I'm wrong. 

The main goal is to correct the timing and the phasing and the end result is a fairly smooth frequency response for each side L&R which will help with imaging due to both sides having a fairly close frequency response.


----------



## DigitalCorrect

DRC does not correct left-right channel timing, but it's very easy to do. Just add enough zero samples (silence) to the beginning of the left correction filter to offset the difference between the delays of the left and right channel audio reaching your ears.


----------



## durwood

DigitalCorrect said:


> DRC does not correct left-right channel timing, but it's very easy to do. Just add enough zero samples (silence) to the beginning of the left correction filter to offset the difference between the delays of the left and right channel audio reaching your ears.


or if using console just use the voxengo delay plugin. Much easier to figure out and adjust.


----------



## old-school

Nice tutorial! I've been wanting to setup something like this for a long time but never sat downt to figure out how to put it all together. With this guide, I'm going to give it a go because I need something to tune my car. I've read this guide over a few times and I think I understand all that is needed. This is what I'm going to get and do. 

1) IBM notebook computer running Windows XP (I have this already)
2) Buy a Behringer EMC8000 microphone (approx. $55)
3) Buy the USB soundcard/preamp called "Mobilepre" (approx $75 used)
4) Buy or make one XLR cable to connect mic and preamp
5) Download some free or eval RTA software to see which I like better. 

All I want to do with this setup is to measure frequency response from 20hz to 20khz. An added bonus will be to measure SPL too. 

Can someone please confirm I'm on the right track?


TIA


----------



## ErinH

old-school said:


> Nice tutorial! I've been wanting to setup something like this for a long time but never sat downt to figure out how to put it all together. With this guide, I'm going to give it a go because I need something to tune my car. I've read this guide over a few times and I think I understand all that is needed. This is what I'm going to get and do.
> 
> 1) IBM notebook computer running Windows XP (I have this already)
> 2) Buy a Behringer EMC8000 microphone (approx. $55)
> 3) Buy the USB soundcard/preamp called "Mobilepre" (approx $75 used)
> 4) Buy or make one XLR cable to connect mic and preamp
> 5) Download some free or eval RTA software to see which I like better.
> 
> All I want to do with this setup is to measure frequency response from 20hz to 20khz. An added bonus will be to measure SPL too.
> 
> Can someone please confirm I'm on the right track?
> 
> 
> TIA


Yep, that's it. 

The best place to get the mic is here. $50 shipped.


----------



## npdang

I forgot, what's the name of that software you guys are all using? AR something?


----------



## old-school

bikinpunk said:


> Yep, that's it.
> 
> The best place to get the mic is here. $50 shipped.


Thanks for the confirmation Erin. Just ordered the mic from zzsounds. Very good price...Thank you.
Now will see if I can win one of this auctions for the USB Mobilepre on Ebay. If I can get this all working, this will be a nice little xmas present to myself


----------



## ErinH

npdang said:


> I forgot, what's the name of that software you guys are all using? AR something?


Not sure you're talking about the one that I use, but it's SmaartLive (one word). Chad uses it as well. 




old-school said:


> Now will see if I can win one of this auctions for the USB Mobilepre on Ebay.


ezsniper.com. First 3 "snipes" are free. Some guys here told me about it and I won a 9815 thanks to that.


----------



## npdang

That's the one I think. I find alot of people are able to get up and running with it pretty easily.


----------



## durwood

npdang said:


> I forgot, what's the name of that software you guys are all using? AR something?


Arta Full version is $80

The demo version is fully functional minus the ability to save or export results but it will do MLS impulse measurements useful for time delay and also frequency response from the impulse measurement as well. Just make sure you set your marker just before the measured impulse otherwise you be wondering why your results look so crappy. It's also got some other features I have yet to play with but it will do waterfall CSD plots as well and it has speech intelligibility measuring too (not sure how that one works yet).


----------



## ErinH

durwood said:


> Arta Full version is $80


Yea, this is probably the one you're talking about. 

Smaart, which is what I use, is f'ing expensive so unless you get it via torrent, your best bet may be ARTA. I use ARTA for t/a, and smaart for FR. Though, I know you can setup smaart to do just about anything according to Chad. I'm hoping he can write up a basic tutorial in the coming weeks/months.


----------



## 300Z

audionutz said:


> Well, got it all hooked up and installed and whatnot...
> BUT, the problem is I am not seeing actual measurements registering on the screens. In other words, I dont think this mic is working, or the mobilepre is NOT receiving the mic input, even though i DO hear the mic sounds thru the puter speakers. THe proggy is putting out the white noise, the pulses, the pink noise, etc thru the audio outputs like it should...it just seems like I cant measure anything. Doesnt this seem strange???


I just ran into the same exact situation here... 
I got 6 different programs and none can measure anything...  every time I run any measurements it just shows me a flat line...

Any idea what the heck could be wrong?

Thanks

Leo


----------



## npdang

Sounds like a config error to me. Like you don't have the right input channel selected in your measurement program.


----------



## 300Z

Thanks for the input Npdang. 

I got LspLab2 and AudioLense 1.2 to work but I'm not sure how accurate the readings are...
On LspLab2 the Impulse response reading isn't right... It doesn't matter if mic is on or off it always get the same readings...  Only FR works... sort of...
And how do I increase the resolution on LspLab2?

On AudioLense things got a bit interesting... the FR reads completely different on both channels, I tried flipping the channels just to check but that didn't change the results. Any clue?

Here's the pics... Sorry about the pic size!

















































Leo


----------



## npdang

You can't with the demo version unfortunately IIRC. 

Audiolense looks good, although the left channel doesn't seem right. I really have to withdraw my reccomendation for the mobile pre, as it seems exceedingly difficult to setup properly. 

I've always used the transit and it was a piece of cake to setup using the line and not mic input, along with a separate pre-amp and mic combo.


----------



## 300Z

Don't I feel like a dumbass now...  

I got the full version of TrueRTA and Smaart v6. But I want to be able to do other measurements other than FR... So far I like AudioLense I just gotta figure out how to make it work properly...
But I'm starting to wonder if the fact that I'm running an active setup thru the computer sound card has anything to do with it?  

Btw, I got the ECM8000 mic but a Behringer Xenyx-802 mixer instead to power the mic.

Leo


----------



## npdang

Depends how you're doing it... what are you using?


----------



## 300Z

I'm just running the Kx Project till I can get a Dcx2496...
Basically a 2way active with 4th order crossovers and some EQ.

Thanks for all the help/input so far.

Leo


----------



## durwood

300Z said:


> Btw, I got the ECM8000 mic but a Behringer Xenyx-802 mixer instead to power the mic.


Pan the mic channel on the mixer to one side completely (Left channel). Then run the fullrange output from your computer soundcard going to your system also into the (right channel) "tape return" on the mixer and turn on tape return. Now on your preamp/mixer output you should have your test signal on the right channel and your measured signal on the left channel. Setup your programs to match this. You might have to play with the gain knobs for the mic channel until you get good results.


----------



## Tode9

How does one go about measuring harmonic distortion? 

I've seen a few charts online (e.g. Zaph's site) that has charts for 2nd thru 5th order distortion, but I haven't been able to find how one makes those measurements. Google gives too many hits and none that are relevant to my question. I've searched here too - maybe not very well - but I haven't found it either.

I have a basic measurement setup - mic, some freeware - I can measure FR. Do I just need more sophisticated software or is there a simple, even if laborious, way to do it?


----------



## npdang

Depends what software you use.

Some programs make it easy. Soundeasy just plays a sine sweep, and then calculates the distortion components for you automatically like you see on Zaph.

Linkwitz uses a 3 tone burst. You can either create those bursts with software, buy them from Linkwitz, or use a hardware tone generator. You will need something that can trigger and record the time response and perform an FFT. Or, you can simply use Praxis which does all the above.

Sample Champion I believe has it's own multi-tone distortion plug-in that's pretty straightforward. It plays any number of simple tones which you pick, then gives you the distortion breakdown.

You could also just play a simple tone, and record the frequency response. It should give you the original tone, along with all the distortion components. 

Bear in mind to window out reflections, and flush mount the driver on a large enough baffle to avoid diffraction. Or, you could use the nearfield technique but be aware that it's upper end usefulness is limited.


----------



## Tode9

Thanks


----------



## bwana

for the macintosh -philes here i have collated the apps that work on MacOSX
Smaart (also available in Windows flavor)
http://www.eaw.com/products/software/EAWSmaart/index.html
These people talk about getting more expensive microphones-I dont know how necessary that is. BTW, do you point the mic up , forward or back?

SpectraFoo
http://www.mhlabs.com/metric_halo/products/foo/

FuzzMeasurePro
http://www.supermegaultragroovy.com/
This one is even featured on the apple site and has a nice how-to


But one thing I do not understand is the use of specific pc cards-these are not audio cards but specifically designed for these kinds of measurements like:
http://www.splcompany.com/prodotti/LINEARX/rta_jr.htm

Can someone enlighten me as to why they havent been mentioned in 18 pages of this thread? Am I way off base and misunderstanding what this card is for?


----------



## durwood

bwana said:


> BTW, do you point the mic up , forward or back?


Thanks for reminding me, I read through this thread the other day. Makes sense to me.

They suggest facing forward for speaker measuring, Up/vertically while measuring room response.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=119164


----------



## ErinH

^ In my experience, when I've tested with mic facing right and test right side only, then mic facing left and test left side only, the "flat response" I get after tuning both L/R individually sounds MUCH better than when doing mic forward and making my changes for both sides at once.


----------



## effenay

bwana said:


> But one thing I do not understand is the use of specific pc cards-these are not audio cards but specifically designed for these kinds of measurements like:
> http://www.splcompany.com/prodotti/LINEARX/rta_jr.htm
> 
> Can someone enlighten me as to why they havent been mentioned in 18 pages of this thread? Am I way off base and misunderstanding what this card is for?


The only benefit to using a solution is that you can get a calibrated mic/interface combo that will generate standardized results for SPL measurement. Most of the enthusiasts on this forum don't really care about SPL competition.

Common pro audio interfaces like the ones most of us are using work just as well, or better, for in-car measurements for tuning purposes.


----------



## npdang

bwana said:


> for the macintosh -philes here i have collated the apps that work on MacOSX
> Smaart (also available in Windows flavor)
> http://www.eaw.com/products/software/EAWSmaart/index.html
> These people talk about getting more expensive microphones-I dont know how necessary that is. BTW, do you point the mic up , forward or back?
> 
> SpectraFoo
> http://www.mhlabs.com/metric_halo/products/foo/
> 
> FuzzMeasurePro
> http://www.supermegaultragroovy.com/
> This one is even featured on the apple site and has a nice how-to
> 
> 
> But one thing I do not understand is the use of specific pc cards-these are not audio cards but specifically designed for these kinds of measurements like:
> http://www.splcompany.com/prodotti/LINEARX/rta_jr.htm
> 
> Can someone enlighten me as to why they havent been mentioned in 18 pages of this thread? Am I way off base and misunderstanding what this card is for?


Expense and portability.

Setups such as Clio or LMS aren't practical for most of us that need a portable, affordable setup.

Also, the card you linked to is for "real time analysis". If you're only interested in measuring the sensitivity of your setup, there are better and more precise tools for that.


----------



## bwana

tnx for the replies. But I thought what we were doing IS real time analysis. Isnt that why it's called RTA? I am thinking of going smaart on a mac OSX (panther). For a mic i was going to use the one supplied with the NADT175 which looks identical to the one supplied with the alpine H650 unit. or should i get a behringer with a preamp? or should i get an audix tr40?


----------



## npdang

bwana said:


> tnx for the replies. But I thought what we were doing IS real time analysis. Isnt that why it's called RTA? I am thinking of going smaart on a mac OSX (panther). For a mic i was going to use the one supplied with the NADT175 which looks identical to the one supplied with the alpine H650 unit. or should i get a behringer with a preamp? or should i get an audix tr40?


There is a subtle difference between the two. 

We're trying to measure the acoustic properties of our cars and stereos. It doesn't have to (and usually isn't) done in real time. In other words, you send a stimulus to the speakers and record the results stimultaneously. In these cases, you usually have significantly more control over how that data is post processed, and what kind of stimulus is used. In other words, so you can "see" the room/system response.

Real time measurement is typically for monitoring live events, where you want to see the frequency and amplitude of something that's ongoing. In other words so you can "see" the sound as it happens.

True, you could adapt either method to suit both purposes, but I find it's generally best to stick with what something is originally designed for.


----------



## bwana

tnx npdang. what is your current favorite software? which mic do you use? i know the behringer has calibration files available but dont know where they are. if i could make sure the mic was not introducing significant errors that would be helpful.


----------



## backwoods

I've been having fun playing with Acourate here recently..

Just to throw out there, but there may be a good solution in dsp to allow for DRC that I think is very easy to move into the car audio domain. In fact, it may be even able to import certain measurements from Acourate for more of an automated dsp without all the steps as Console.

I'm playing with a beta right now, using Smaart and Acourate for measurements and have had some good results recently..

Hopefully I can fill you guys in on more here soon!


----------



## npdang

I use Praxis.

I wouldn't worry about the Behringer mic's accuracy. It's pretty reasonably accurate. Even if you could find a calibration file, it wouldn't help. It has to be for your mic, as each capsule is different.


----------



## durwood

backwoods said:


> I've been having fun playing with Acourate here recently..
> 
> Just to throw out there, but there may be a good solution in dsp to allow for DRC that I think is very easy to move into the car audio domain. In fact, it may be even able to import certain measurements from Acourate for more of an automated dsp without all the steps as Console.
> 
> I'm playing with a beta right now, using Smaart and Acourate for measurements and have had some good results recently..
> 
> Hopefully I can fill you guys in on more here soon!


So you have finally seen another light?


----------



## backwoods

lmao...

You'll definitly dig what I am up to... In fact, waiting on an email right now!


----------



## bwana

i decided to go with the m-audio fast track pro. i will be using it for other things as well, but for this project (analyzing a car or a room audio system) it will work well with a behringer mic. I read the bit about calibrating a pc - TRUE RTA for dummies (http://www.avsforum.com/avs-vb/showthread.php?t=572477&page=6) but am a little confused because of the multitude of in/outputs on the fast track pro. there are 2 balanced inputs for 2 microphones. these inputs are actually combo jacks that accomodate either an xlr. 

i assume to calibrate this device, i would need to go from the balanced trs outputs to the balanced mic inputs, yes? this would require male TRS-> male XLR

Or should i go this way: rca output -> TS male mic connection?

or should i go from headphone jack->splitter-> 2 TS male mic connections

what about the voltages-if i use the headphone vs balanced out vs unbalanced out and pipe that into the microphone input---wont i blow the mic input? after all the microphone usually does not supply voltage and phantom power is coming out of the microphone jack. In setting up a calibration loop, we are piping voltage into the microphone circuit.


----------



## Tode9

When running sine sweeps, is there a rule of thumb towards how long of a capture window one should have to look at the driver impulse vs. reflections? 5ms, 10ms, more/less, beyond the initial impulse? I'm sure there are numerous factors that play into it and no optimum number, like if a driver were very close to a reflecting surface or the duration of the sine sweep itself, etc. However, is there a "general window" that is "reasonably accurate" in "most situations"?


----------



## Juice Hifi

300Z said:


> Don't I feel like a dumbass now...
> 
> I got the full version of TrueRTA and Smaart v6. But I want to be able to do other measurements other than FR... So far I like AudioLense I just gotta figure out how to make it work properly...
> But I'm starting to wonder if the fact that I'm running an active setup thru the computer sound card has anything to do with it?
> 
> Btw, I got the ECM8000 mic but a Behringer Xenyx-802 mixer instead to power the mic.
> 
> Leo



I will gladly help you with making Audiolense work.


----------



## cotdt

any free programs?


----------

