# setting gain properly



## spmpdr

This is the best most informative gain setting thread i have seen online.Its easy to understand and use.

HOW TO SET GAINS

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ADD version -

1. Play a typically loud music CD in your headunit. Set volume to 75%. Wear ear protection.
2. Starting with the amp gains at their lowest setting, slowly raise one gain at a time until you hear clipping from the corresponding speaker. This will sound like audible distortion.
3. Once you've found the clipping point, back the gain down until you no longer hear the distortion.
4. Repeat for any addt'l gains on the amp/amps.
5. Your new maximum volume setting on the headunit is 75%, never exceed that for happy, healthy speaker life.

(This is the quick & dirty method, it'll get you 80% to proper settings. Read on for the other 20%.)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


How to do things right -

What's gain?
Also known as input sensitivity, gains are the small, typically recessed "volume knobs" on most equipment between the speakers & the headunit. All amps have them, also many EQ's, line output converters, some crossovers.

What's it for?
The idea is to properly match the output from different pieces of gear so that each communicates the cleanest signal to the other, resulting in maximum performance and minimal noise & risk of damage.

Know your enemy - Clipping.
Clipping is the tech term for the distortion that occurs when an amplifier is pushed beyond it's capabilities. In simple terms it sounds like significant distortion of the musical peaks. So for instance a big drum strike will sound muddy or distorted when turned up, but remains clear at a lower volume. That's clipping. What's happening is the amp momentarily runs out of power.

To properly understand this w/o an engineering degree you need to know the difference between constant power (RMS) and peak power. Constant power, very simply, is the amount of juice your amp can produce consistantly. Since there are some standards for measuring this it is one of the few benchmarks we have for amplifiers. But since sound waves are exactly that - waves, with peaks & valleys - understand that an amp's output is never constant, it has to increase & decrease with the music signal.

The amp's "reserve power" is what it uses to deal with the peaks in the music. This is called peak power, or my favorite, headroom. Headroom is typically about twice the RMS power of an amp, but can only be sustained for a few milliseconds before the amp gets totally winded.

So a good way to think of this is a 10 yr old jumping on a bed - that's the music signal. The bed is the amp's RMS power, the ceiling above is the headroom limit. If the kid jumps too high he whacks his head - that's clipping. Do it a couple times & he'll survive. Do it repeatedly & there WILL be permanant damage. This is the single biggest speaker killer out there.

So the object of the game is to adjust the bed height (by using the gains) to the right height so the kid can jump around like a caffeinated monkey without ever whacking into the ceiling. So setting the gains properly allows you to get the amp's maximum output without overtaxing the equipment. With me so far?

A few other basics -
To do this properly you'll need a few things:

Ear protection. Stuff some cotton in your ears if you don't have anything better.

A test CD with a sine wave set to 0db, a 50-80hz stereo tone is ideal. This is important - it's far more accurate than using a music CD. You can purchase these at most any guitar or pro music stores, Amazon, or download a program to make your own. Making your own isn't recommended since there are a lot of variables in computers that can affect the final product.

If you have a crossover, you'll need test tones within the frequency range for each amp. For instance if you have a dedicated sub amp crossed over at 80hz, get a 60hz test tone. For your mains, work with a 120hz tone. If you have a 3-way or more crossover, adjust appropriately, just be sure the test frequency is within the bounds of the speaker range. Test each frequency seperately.

Fader, tone controls, loudness/expansion, etc.
Ideally you'll have the sound from your headunit/EQ completely flat on a normal basis. If so, be sure everything's this way before you test. However, if you KNOW you'll have the bass boost activated, some sort of expansion, or the tone controls preset in some way then go ahead & set them before you test.

Otherwise it's best to have everything flat. If you choose to adjust the tone controls later & leave them that way you can always repeat the process. Regardless, be sure the fader & balance are zeroed out.

Dedicated sub volume controls
A lot of amps have outboard sub volume knobs & headunits frequently have dedicated internal sub volume adjustments. If you plan on using these they should be maxed before setting your gains. If you're not going to use them, best to de-activate them.

Set all amp gains to their lowest point before starting. Usually full counter-clockwise.

Input sensitivity switches
If your amp has a selector switch for different input sensitivities, start by setting it to the highest setting. These are typically expressed in voltages, for example .2-1v, 1-3v, 3-8v. Start with the higher numbers (ex. 3-8v) (lowest sensitivity). If you can't get the amp to clip at those settings, try the next one down until you find the clipping point. You can disregard generally what the markings themselves say since there's no real standard for measuring that stuff. Never trust your system's well-being to those voltage numbers, they're just a guideline best ignored.

Work with one gain at a time.
For example, if you have a L&R gain for your front speakers, you'll be working with each side seperately. If multiple amps, unplug all but the amp you're working with. If a 4+ channel amp, typically you'll have only a single L & R gain, so treat it like a 2 channel. If it has more gains, isolate each & adjust seperately.

Play your test tone thru the headunit. Adjust your headunit volume to 75% of max.
This doesn't need to be precise, just be sure you know where this setting is b/c it's now the HIGHEST you'll ever turn up the volume on the headunit.

(But the amps go to 11...! You're using 75% volume because some CD's will be louder than others. Also b/c there's a small amp in the headunit that will clip if pushed too far. Trust me on this one.)

Now turn up the gain you're working with until you hear the tone quality change - it'll be a distinct change in the tone, there will be distortion. This is where your amp clips. Now turn the gain back down to just below where that distortion occurs. That gain's now set. Repeat for all other gains. Repeat for all other amps.


Final tweaking -
Have an EQ? Want to use the "loudness" button? Want to adjust the bass/mid/treble controls? If you're making minor tweaks (+/-1) there's no real need to worry about gains. If you're talking about bigger changes (+4/-3, etc) you may want to run the tones again to be sure you're still set right.

Also now that the gains are properly set you can adjust them DOWN to balance your system. Need more front volume but don't have a fader? Turn down the rear gains. Sub underpowered? Turn down the mains. The important thing is to never turn them UP from where they are, just down.


A few other notes -

Can't I just use an O-scope or DMM to set gains?
Sure, IF you know the exact output (rarely the rated output) of your amp and you're a freakin' genius with your toys. Generally more accurate & far easier to use your ears.

What about the gains on the EQ/X-over/line-output converter?
Ooh, good question. The general idea here is to follow the same process but use the gains that are the furthest UPSTREAM (I.E. closest to the headunit) and set all the others to their lowest setting. This will send the hottest signal possible thru all the components. Just remember that anywhere the signal splits you'll have to set them there also. For example, if you have a LOC & an outboard crossover you'll need to set gains on both, starting with the LOC. This can get tricky. Let your ears guide you.

What if my headunit says "9v output" and the amp only says "5v input?"
Eh, doesn't really matter. Again, there isn't really any set standard for measuring this stuff & it's usually just marketing. Also remember that music is a wave, not a line, so that rated output is usually a max, not a constant. Just set everything according to the above process, nothing changes.


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## comforta

Great Post.


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## eharri3

comforta said:


> Great Post.



I once tried it by playing tones through the head unit for my mid/high amp. I think I played it for a second or two too long at or near the clipping level as I started to smell something funny. I hit the pause button and no permanent damage was done but I think it should be emphasized that you don't exactly want to leave an unattenuated test tone playing through an actual speaker at high volume all day long.


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## chad

eharri3 said:


> I once tried it by playing tones through the head unit for my mid/high amp. I think I played it for a second or two too long at or near the clipping level as I started to smell something funny. I hit the pause button and no permanent damage was done but I think it should be emphasized that you don't exactly want to leave an unattenuated test tone playing through an actual speaker at high volume all day long.


You will shred a tweet in an active set up LONG before you hear clipping.


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## kyheng

I don't know... But using test tones can really help on setting gain? If to relate it with %, it will be only 50% from my opinion. There's a way to avoid clipping which is getting amp output power > speaker rated power by 10-50%.
Anyway I'm using 1-10-100 for 2-way setup and 1-2-4-8 for 3-way setup.


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## chad

kyheng said:


> I don't know... But using test tones can really help on setting gain?


Not really but it makes people feel all technical and stuff.


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## dougc

How can I tell if the amp is clipping or the speaker is distorting, or is it the same?


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## kyheng

Chad : Well, for me, listening to music is sunjective and is enjoying. Not using the maths to calculate this or that....


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## chad

some people think that in order to tune all the passbands need to clip at the same time, and if you've ever heard this then you would run for your life... you better like top end!


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## kyheng

^Yeah, people just like to drive the drivers to its limits sometimes. While I still prefer to have some room for it, even my HU's volume at 100% and still not clipped. That's why equipment selections are more important.


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## mgray

I though you start with the closest gain setting to the instrument and work towards the amp, not the other way around? Ie. Set preamp gain first, then amp gain?


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## caraudioguru

Using sine wave at "0dB" is not a good idea, unless you are using a scope and a 10 to 1 "box" (10K ohm 2-10 watt resistor and a 1K ohm 2-10 watt resistor) so you can load down everything and then , as an alternative method use a Radio Shack "Amplifier/Speaker" (their sku 277-1008C) to listen to the clipped tone at every signal point (input /output of signal processors, amplifiers etc). I've burned up a LOT of woofers doing the sinewave test (in less than 20 seconds too!!) So be VERY careful with 0dB sinewaves!!!

I've used the method that spmpdr speaks of for over 30 yrs all over the world. We listen to music,not sine waves. The sine wave method is the most accurate, but then you should do a 5, 10 or 15 dB overlap on the sub amplifier to give you "headroom" This would mean you have a 40 Hz 0dB, 40 Hz -5 dB and a 40 Hz -10 dB sine wave -and an Oscilloscope. The only CD I know that has that and 1Khz and 8kHz set up the same way is AutoSound 2000 - CD104. Which is what I use all the time. A TPI440 scope (all of $298 bucks) and that disc you are good to go!!

Like spmpdr says the easiest method is to turn the headunit up about 75% (unless you have a scope and a 1Khz 0 dB test tone AND a scope! And know where your headunit "clips!) Thje only difference I teach is to unhook subs for a second and set up your high pass drivers first (mids and highs) as these are usually the limiting factor, NOT the sub. Once you've adjust the mids and highs to just below 'yelling ans screaming:, then tun the whole system down (at the Headunit) and then reconnect the sub setup and match the subwoofer level to the rest of the system at a normal listen level. Remember that the object is to get ALL the gain at the beginning and NO gain at the end (input gains should be all the way down -assuming you have a 4 volt deck) That way you don't have the "hissing snake syndrome)  And the best sound quality and dynamic range. Good luck guys!


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## spmpdr

caraudioguru said:


> Using sine wave at "0dB" is not a good idea, unless you are using a scope and a 10 to 1 "box" (10K ohm 2-10 watt resistor and a 1K ohm 2-10 watt resistor) so you can load down everything and then , as an alternative method use a Radio Shack "Amplifier/Speaker" (their sku 277-1008C) to listen to the clipped tone at every signal point (input /output of signal processors, amplifiers etc). I've burned up a LOT of woofers doing the sinewave test (in less than 20 seconds too!!) So be VERY careful with 0dB sinewaves!!!
> 
> I've used the method that spmpdr speaks of for over 30 yrs all over the world. We listen to music,not sine waves. The sine wave method is the most accurate, but then you should do a 5, 10 or 15 dB overlap on the sub amplifier to give you "headroom" This would mean you have a 40 Hz 0dB, 40 Hz -5 dB and a 40 Hz -10 dB sine wave -and an Oscilloscope. The only CD I know that has that and 1Khz and 8kHz set up the same way is AutoSound 2000 - CD104. Which is what I use all the time. A TPI440 scope (all of $298 bucks) and that disc you are good to go!!
> 
> Like spmpdr says the easiest method is to turn the headunit up about 75% (unless you have a scope and a 1Khz 0 dB test tone AND a scope! And know where your headunit "clips!) Thje only difference I teach is to unhook subs for a second and set up your high pass drivers first (mids and highs) as these are usually the limiting factor, NOT the sub. Once you've adjust the mids and highs to just below 'yelling ans screaming:, then tun the whole system down (at the Headunit) and then reconnect the sub setup and match the subwoofer level to the rest of the system at a normal listen level. Remember that the object is to get ALL the gain at the beginning and NO gain at the end (input gains should be all the way down -assuming you have a 4 volt deck) That way you don't have the "hissing snake syndrome)  And the best sound quality and dynamic range. Good luck guys!


Great insight and I too don't tune exactly as this article states most of the time i use music with different drums and bells and guitar riffs to get the sound i prefer.I set the gain on the mids first and then on the highs then tune those together with no sub playing then i unplug those and set sub gain and then tune the subs to the mids /highs


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## chad

In my fledgling days of pro audio there was a kit you could build called a ''clip cop'' much like the rat shaq amp, damn i was stoked to find out that they are still made, it detects clipping quite well. When a signal clips your are gonna get harmonics, the clip cop uses a piezo element and some external support components, it's passive IIRC, you increae gain on ANYTHING till that piezo element rings and bam.. there's the clipping... the harmonics make it ring. since a piezo element has an frequency curve the increases as impedance goes down (why they are "touted" as crossoverless) this inherent trait makes them just scream when you hit clipping...... kinda cool eh?

I have looked all over the net for the kit designs, something tells me that someone latched on and now it's "no longer a kit" I left mine at an old place of employment, next time I swing by for coffee I'll open it up.


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## ErinH

^ sounds a lot easier than lugging around an oscope. 

*sub'd


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## kvndoom

If it helps any...

parts list

putting it together


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## chad

BAM.


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## ErinH

LOL.

I think I'll just stick to lugging the oscope around.


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## chad

bikinpunk said:


> LOL.
> 
> I think I'll just stick to lugging the oscope around.


think outside the box......... rocket scientist.


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## ErinH

Hey, now! 

I read the DIY and spec sheet... and saw how much work will be involved. I have an oscope already, so I'll just stick with that. No sense in building one of those in my case for $46+ as I'll just use my oscope that I already paid for. 
However, if I didn't have one, I'd give this DIY version a shot. So, thanks, kevin (I assume this is your name), for posting the links. 
Great idea for those who don't want to lug around an oscope or try to find a cheap one on the bay. :thumbsup:


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## chad

you are not gonna need the transmitter side THAT bad.


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## drtool

Clip cop, learn sumptin new every day.


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## jimp

dumb question, directions say to play a loud CD, would a loud song on an ipod be the same or should it be a CD for some reason?


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## sparky3489

Do a search for "Sparky's Audio Survival Guide"


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## chad

sparky3489 said:


> Do a search for "Sparky's Audio Survival Guide"


I did and it was an epic fail busy-ass webpage.


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## sparky3489

It's all I have since I can't post links, THAT'S EPIC FAIL!!!!


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## sparky3489

Audio-Calc.xls - File Shared from Box.net - Free Online File Storage

You'll need a multi-meter (AC voltmeter, $15 from Radio$hack), Microsoft Excel and a way to burn an audio CD from an MP3 (test tone included).

If you don't have Excel, you can download (free) OpenOffice by Java (Sun Micro systems) from here to read spreadsheets (and you thought spreadsheets were for business) - download: OpenOffice.org Downloads

Oh sure, NOW I can...


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## chad

facepalm


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## sparky3489

Anywho, there's nothing like it that I've ever seen. 

Much like this - The creation of a digital LED VU meter - CarStereoForum.Net


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## chad

sparky3489 said:


> Anywho, there's nothing like it that I've ever seen.
> 
> Much like this - The creation of a digital LED VU meter - CarStereoForum.Net


Common circuit.. many even have weighting 
That has NO weighting.. therefore it's not vu.

rise and fall needs to be 300 Ms.


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## chad

NOW, you could copy a dorrough that has peak (like yours on a dot) and VU (NOT like yours) on a bar.

Dorrough


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## sparky3489

I didn't want weighting. Regardless, it's still a voltage unit meter. A common circuit yes, but 100% custom.

Much like this - PC Interface Project - CarStereoForum.Net

_______________________________________________________

First off, nice "Welcome to the forum, enjoy your stay." NO, I get flack from immature fappers.

Second (benny), that's not my page and I never provided a link to that page as you say I did. 

Third, I don't see ANYTHING from any of you that that's sofisticated as is my excel sheet.

Chad, I guess you'd better tell the fine folks over at National Semiconductor that they don't know what they're talking about, "The LM3916 is a monolithic integrated circuit that senses analog voltage levels and drives ten LEDs, LCDs or vacuum fluorescent displays, providing an electronic version of the popular VU meter."
Boy those guys over at NS sure are stupid.

...and finally to sam3535, subwoofers can be disconnected AT THE SUBWOOFER. 

I had thought the intelligent factor would be substantial on this forum, sadly I was mistaken. I mean I am at the right place, right? DIY Mobile Audio?

I did something MYSELF to share and WOW what a reception. Top knotch and EPIC FAIL!!!!!!


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## chad

it is NOT a VU meter, it's a light-show.

VU is a weighted measurement, unlike peak reading only, it is a more accurate representation of loudness.

For example, especially in your demo music, a VU meter may hover around 0dB and still bang a peak light set at +16dB.

A voltage unit is a volt, it may me a voltmeter, but not a VU meter. And even most voltmeters...as you linked... are weighted.


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## chad

simple parallel control, not to pee in your beer but this is freshman EE stuff (back in the early 90's) man. And of all of us here I'm probably one of the only few that still has a computer with a parallel port 

Only because I do things on serial (easy RF data/control) and to find a computer with 2 serial you get a free parallel.


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## benny

sparky3489 said:


> Do a search for "Sparky's Audio Survival Guide"


What the **** was that ****?! You should be bant for recommending anyone go to that abortion of a page.

HERE'S YOUR LINK TO A GIANT BAG OF FAIL.


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## sam3535

And I quote from this abortion of an excel file, in the gain control tab for setting your gains:

"4) Unhook all subwoofers from the amplifier at the amplifiers (this is optional as some amplifiers won't allow you to do this, use earplugs!!!)"

AWESOME!!!!!!


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## sparky3489

See post #32 since my post is up for deletion because it has spam like qualities. Nice!


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## chad

sparky3489 said:


> See post #32 since my post is up for deletion because it has spam like qualities. Nice!


It's just up for review, it's all good, I was once a mod here, if it showed then it got accepted 

Where are you in mid-Illinois? It said on another forum 90 miles south of Chicago and that's DAMN close to where I grew up.


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## sparky3489

Well Chad, Champaign was only 50 miles south of where I grew up. A little town right on 57.


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## chad

I grew up in Gibson City... not too far from you  Yer one of them Iroquois county folk


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## sam3535

sparky3489 said:


> See post #32 since my post is up for deletion because it has spam like qualities. Nice!


I read your post and I am confused. What exactly is your problem with what I posted? While you and I obviously understand that speaker wires can be disconnected at the sub, the person who compiled the excel file doesn't; hence the suggestion to wear earplugs. Calm down there sparky.


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## sparky3489

Gilman isn't too far from there. I live in Pontiac now.


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## chad

sparky3489 said:


> Gilman isn't too far from there. I live in Pontiac now.


The truck stop in Gilman had the best biscuits and gravy known to man.


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## sparky3489

sam3535 said:


> ... the person who compiled the excel file doesn't; hence the suggestion to wear earplugs. Calm down there sparky.


Ummm, if you leave the subs connected and play a 60Hz tone at 3/4 volume, it can be loud. 

"4) Unhook all subwoofers from the amplifier at the amplifiers (this is optional as some amplifiers won't allow you to do this, use earplugs!!!)"

Meaning some amplifiers will not work propelry without a load. These are the older amps. Newer amps don't have this problem (typically). Besides, did you read the disclaimer on the first page?

...and I compiled the excel sheet thank you very much.


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## chad

The amp should always be under load, hence the need for dummy loads. If it makes output or not, you need loads to get an accurate measurement.


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## sam3535

sparky3489 said:


> Ummm, if you leave the subs connected and play a 60Hz tone at 3/4 volume, it can be loud.
> 
> "4) Unhook all subwoofers from the amplifier at the amplifiers (this is optional as some amplifiers won't allow you to do this, use earplugs!!!)"
> 
> Meaning some amplifiers will not work propelry without a load. These are the older amps. Newer amps don't have this problem (typically). Besides, did you read the disclaimer on the first page?
> 
> ...and I compiled the excel sheet thank you very much.


The VAST majority of persons playing a 60hz test tone to their sub while attempting to set gains will blow the sub. That's why I quoted #4. If nothing else, change the spreadsheet to say disconnect all speakers. It's not my fault you left that out. I set my gains by ear usually, anyway.

From what I saw after your post, you were just catching the same crap all of us catch on here at some point. So...welcome to DIYMA!


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## sparky3489

chad said:


> The truck stop in Gilman had the best biscuits and gravy known to man.


K & H is still there.


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## sparky3489

sam3535 said:


> The VAST majority of persons playing a 60hz test tone to their sub while attempting to set gains will blow the sub. That's why I quoted #4. If nothing else, change the spreadsheet to say disconnect all speakers. It's not my fault you left that out.
> 
> From what I saw after your post, you were just catching the same crap all of us catch on here at some point. So...welcome to DIYMA!


Not if you follow the directions to a T. Gain to it's least sensitive and such. I admit it is a bit vague in places, but I'm limited on room for text so I did the best I could.

Thank you.


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## sam3535

sparky3489 said:


> Not if you follow the directions to a T. Gain to it's least sensitive and such. I admit it is a bit vague in places, but I'm limited on room for text so I did the best I could.
> 
> Thank you.


Excel sucks but I have to use it daily to track incident and injury trends and am now better at using it as opposed to Word with simple documents. At least you had the foresight to lock it with a password.


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## sparky3489

sam3535 said:


> Excel sucks but I have to use it daily to track incident and injury trends and am now better at using it as opposed to Word with simple documents. At least you had the foresight to lock it with a password.




Some other programs of interest? 
(WARNING: Cheesy 16-bit programming ahead!)

Passive Bass Blocker calculator BassBlock.EXE - File Shared from Box.net - Free Online File Storage

Series LED resistor calculator LEDCalc.EXE - File Shared from Box.net - Free Online File Storage

LM317 calculator - LM317.EXE - File Shared from Box.net - Free Online File Storage


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## chad

bah, I need to look at the LED calc tomorrow, that looks handy and I'm too lazy to boot over to windows.


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## Gill

caraudioguru said:


> Using sine wave at "0dB" is not a good idea, unless you are using a scope and a 10 to 1 "box" (10K ohm 2-10 watt resistor and a 1K ohm 2-10 watt resistor) so you can load down everything and then , as an alternative method use a Radio Shack "Amplifier/Speaker" (their sku 277-1008C) to listen to the clipped tone at every signal point (input /output of signal processors, amplifiers etc). I've burned up a LOT of woofers doing the sinewave test (in less than 20 seconds too!!) So be VERY careful with 0dB sinewaves!!!
> 
> I've used the method that spmpdr speaks of for over 30 yrs all over the world. We listen to music,not sine waves. The sine wave method is the most accurate, but then you should do a 5, 10 or 15 dB overlap on the sub amplifier to give you "headroom" This would mean you have a 40 Hz 0dB, 40 Hz -5 dB and a 40 Hz -10 dB sine wave -and an Oscilloscope. The only CD I know that has that and 1Khz and 8kHz set up the same way is AutoSound 2000 - CD104. Which is what I use all the time. A TPI440 scope (all of $298 bucks) and that disc you are good to go!!
> 
> Like spmpdr says the easiest method is to turn the headunit up about 75% (unless you have a scope and a 1Khz 0 dB test tone AND a scope! And know where your headunit "clips!) Thje only difference I teach is to unhook subs for a second and set up your high pass drivers first (mids and highs) as these are usually the limiting factor, NOT the sub. Once you've adjust the mids and highs to just below 'yelling ans screaming:, then tun the whole system down (at the Headunit) and then reconnect the sub setup and match the subwoofer level to the rest of the system at a normal listen level. Remember that the object is to get ALL the gain at the beginning and NO gain at the end (input gains should be all the way down -assuming you have a 4 volt deck) That way you don't have the "hissing snake syndrome)  And the best sound quality and dynamic range. Good luck guys!


How to set gain using 5db,10db test tones?What would be the reference point?or just play the cd and see when it clips on scope?
I am not able to understand the use of 0db,5db,10db and 15db TT in an order!!


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## sparky3489

Well Gill, I'm not sure why "Using sine wave at "0dB" is not a good idea" wth a DMM when it's perfectly fine to do so. 

An example of the same method from Elemental Designs 




Be aware that high powered resistors are VERY expensive. Using the sub(s) is actually the best method.


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## ErinH

it's a matter of volume overlap at the headunit vs. noise floor max.

everything EXCEPT the amp is set to max clipping via a 0dB tone.
That ensures you have the best signal you can get going to the amplifier. Out of the amp, you could use 0dB again, but as noted, we don't listen to test tones. So, use an attenuated tone to get a more 'musical' setting which also maximizes your 'headroom' on the volume knob. The idea is that at -5dB or even -10dB, you've allowed yourself enough volume control up front while not dipping into distortion levels.

If you set everything with a 0dB tone you're maxing yourself out early and not taking advantage of your system's dynamic capability.
If you set everything with an attenuated tone, you're not maximizing the amount of clean signal passing to your amplifiers and you're also choking yourself in the volume department.

Simply put, it's a culmination of the two methods. Not a steadfast rule, but one that I follow myself as do many others.


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## sparky3489

bikinpunk said:


> ..... So, use an attenuated tone to get a more 'musical' setting which also maximizes your 'headroom' on the volume knob. ....
> 
> 
> .... If you set everything with an attenuated tone, you're not maximizing the amount of clean signal passing to your amplifiers and you're also choking yourself in the volume department. .....



HUH?!?!?!? Umm, thanks confucius!

I'm a Peavey Media-Matrix certified audio engineer and I have no clue what you just said.

It doesn't have to be loud to sound good


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## ErinH

re-read what I said.

I said set the amp with an attenuated tone.

Then I said what happens if you set everything when an attenuated tone. 

I didn't say it has to be loud to sound good. Ever had a recording that's not as loud as the rest of your music?


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## sparky3489

bikinpunk said:


> it's a matter of volume overlap at the headunit vs. noise floor max.....
> 
> .....So, use an attenuated tone to get a more 'musical' setting which also maximizes your 'headroom' on the volume knob. .....
> 
> .....If you set everything with an attenuated tone, you're not maximizing the amount of clean signal passing to your amplifiers and you're also choking yourself in the volume department. ......



An aweful lot about volume.


----------



## ErinH

sparky3489 said:


> An aweful lot about volume.


What's your point?
That's one of the points I'm driving home. Gain overlap gives you the headroom on the volume knob you need for more 'quiet' songs, while also giving you a good mix of clean signal vs. noise floor vs. distortion levels.
As I said a few posts up, it's a compromise. I honestly don't know how I explain it any simpler. 

If you don't agree with the method, tell us why. I'm open to hearing it. 

There's about 3 threads on this same method and no one else has had made 5 subsequential posts questioning the method other than you. If you want, you can search those out. I've said all I can about the topic. Maybe you can ask Chad, another pro sound guy, to explain it to you. He understands it just fine... and I'm sure he's a certified whatchacallit, too.


----------



## sparky3489

I don't disagree with the method at all. I just think it's a lot to go through just for car audio. There's no chance in hell for car auidio to be as good as home audio (properly set up in both cases) so why go through all the trouble just to make an insignificant difference between methods?


----------



## jaysalti

sparky3489 said:


> I don't disagree with the method at all. I just think it's a lot to go through _just_ for car audio


blasphemy


----------



## sparky3489

Ha ha!


----------



## BigAl205

sparky3489 said:


> Third, I don't see ANYTHING from any of you that that's sofisticated as is my excel sheet.


:laugh::laugh::laugh:


----------



## sparky3489

BigAl205 said:


> :laugh::laugh::laugh:


Yeah, if you could only see the hidden page with all the calculations on it.



...and you have it wrong.

It's the Redundancy Dept of Redundancy


----------



## BigAl205

sparky3489 said:


> Yeah, if you could only see the hidden page with all the calculations on it.
> 
> 
> 
> ...and you have it wrong.
> 
> It's the Redundancy Dept of Redundancy


I downloaded the spreadsheet and I'm impressed. I was just laughing at your spelling of "sophisticated". It reminds me of Homer Simpson telling Lisa that his job was sophistamicated. :laugh:


----------



## sparky3489

Oh, ha ha. I didn't even realize. OOPS! 

It still could use some improvements.


----------



## ca90ss

sparky3489 said:


> There's no chance in hell for car auidio to be as good as home audio (properly set up in both cases) so why go through all the trouble just to make an insignificant difference between methods?


Home audio will never be as good as sitting at a live performance either so does that mean we should give up on that too?


----------



## sparky3489

ca90ss said:


> Home audio will never be as good as sitting at a live performance either so does that mean we should give up on that too?


I never said anything about giving up, but it's the same as an S-Video connection on an RF modulator.


----------



## chad

sparky3489 said:


> Chad, I guess you'd better tell the fine folks over at National Semiconductor that they don't know what they're talking about, "The LM3916 is a monolithic integrated circuit that senses analog voltage levels and drives ten LEDs, LCDs or vacuum fluorescent displays, providing an electronic version of the popular VU meter."
> Boy those guys over at NS sure are stupid.


Oh for the love of god. I have a 350 Piston here, but that does not mean I have a car version of the popular Chevy Nova.

You just claimed to be a Media Matrix trained tech but you don't know what VU is. YOU DID NOT BUILD A VU METER, GET IT THRU YOUR HEAD. 

The guys at NS are NOT stupid, it's a Ladder chip, not rocket science mang, and there are places that explain to you as to how to set the weighting for VU. 

Don't be a smartass to me Sparky. I've got my time in... LOTS OF TIME.


----------



## t3sn4f2

sparky3489 said:


> I don't disagree with the method at all. I just think it's a lot to go through just for car audio. There's no chance in hell for car auidio to be as good as home audio (properly set up in both cases) so *why go through all the trouble just to make an insignificant difference between methods*?


Because its the best way to deal with a problem that is way more prevalent in car audio then it is in home audio.

Component noise floor.


----------



## sparky3489

Wow, is it really that important to you what I call something? If you look back, I did define it as a "Voltage Unit Meter" which is exactly right.


----------



## Oliver

sparky3489 .... and a very sofisticated one


> I did define it as a "Voltage Unit Meter" which is exactly right.


That would be very useful to me if it had "amberlamps" , they are preferred by sofisticated Tyrone in Oakland, Cali


----------



## sparky3489

t3sn4f2 said:


> Because its the best way to deal with a problem that is way more prevalent in car audio then it is in home audio.
> 
> Component noise floor.


Doesn't seem to be a problem at moderate volume levels.


----------



## sparky3489

a$$hole said:


> sparky3489 .... and a very sofisticated one
> 
> 
> That would be very useful to me if it had "amberlamps" , they are preferred by sofisticated Tyrone in Oakland, Cali



Technically they are LEDs and you can have just about any colour you want.

Do you have pics of your PCB?


----------



## ChrisB

bikinpunk said:


> If you set everything with a 0dB tone you're maxing yourself out early and not taking advantage of your system's dynamic capability.


I used a 0dB test tone to derive output into a 4 ohm dummy load for my mids and highs amplifiers in my Civic. I just wanted to see what kind of output they could potentially receive at volume level 26 since my amp is capable of producing close to THREE times their rated RMS power handling.

The speakers were rated to handle 100 watts RMS and each amplifier outputs 120 watts RMS @ volume level 26 with the 0 dB test tone and gains that can't go any lower. Unfortunately, those same amplifiers will output 300 watts RMS each just prior to clipping with the same dummy load. I hope I didn't limit my system's dynamic capability by using the 0 dB test tones.


----------



## chad

sparky3489 said:


> Wow, is it really that important to you what I call something?












Is it important that they don't call Tylenol birth control?


----------



## sparky3489

ChrisB said:


> I used a 0dB test tone to derive output into a 4 ohm dummy load for my mids and highs amplifiers in my Civic. I just wanted to see what kind of output they could potentially receive at volume level 26 since my amp is capable of producing close to THREE times their rated RMS power handling.
> 
> The speakers were rated to handle 100 watts RMS and each amplifier outputs 120 watts RMS @ volume level 26 with the 0 dB test tone and gains that can't go any lower. Unfortunately, those same amplifiers will output 300 watts RMS each just prior to clipping with the same dummy load. I hope I didn't limit my system's dynamic capability by using the 0 dB test tones.


You do know a dummy load won't have the same impedance as an actual speaker?


----------



## chad

sparky3489 said:


> You do know a dummy load won't have the same impedance as an actual speaker?


it has resistance, and albeit not reactive it's better than nothing...... Speakers don't care for tones too much, especially mids and tweets.


----------



## sparky3489

chad said:


> Is it important that they don't call Tylenol birth control?


Oh, I didn't know I was the Tylenol company!!!


----------



## sparky3489

chad said:


> it has resistance, and albeit not reactive it's better than nothing...... Speakers don't care for tones too much, especially mids and tweets.


Agreed.


----------



## ChrisB

sparky3489 said:


> You do know a dummy load won't have the same impedance as an actual speaker?


It is better than those tutorials where people set their gains by voltage with nothing but a DMM connected to their amplifier's speaker outputs! Plus, after repairing an amplifier, I would rather use dummy loads for long term testing than subwoofers because it keeps my ears happy!


----------



## sparky3489

ChrisB said:


> It is better than those tutorials where people set their gains by voltage with nothing but a DMM connected to their amplifier's speaker outputs!


Not a thing wrong with those tutorials or that method of gain adjustment. It's better than by ear as a lot of people haven't a clue what they're even listening for.



ChrisB said:


> Plus, after repairing an amplifier, I would rather use dummy loads for long term testing than subwoofers because it keeps my ears happy!


Repairing amps with happy ears? That doesn't follow. Ear plugs were invented a long time ago and are a lot cheaper than high-powered resistors.


----------



## benny

sparky3489 said:


> Not a thing wrong with those tutorials or that method of gain adjustment. It's better than by ear as a lot of people haven't a clue what they're even listening for.
> 
> 
> 
> Repairing amps with happy ears? That doesn't follow. Ear plugs were invented a long time ago and are a lot cheaper than high-powered resistors.


I'll come right out and say it: Good lord you're an idiot.


----------



## sparky3489

Design brought to you by the fine folks over at Decware, East Peoria IL
Audiophile Tube Amps and Tube Gear from DECWARE


----------



## benny

Nice bandpass box. You know horns don't work in cars, right?

In be4 DECKERT IS GOD


----------



## sparky3489

benny said:


> I'll come right out and say it: Good lord you're an idiot.


How so? I've already shut you down once, ready for it again?


----------



## sparky3489

benny said:


> Nice midbass horn motor. You know horns don't work in cars, right?


Who says? YOU! HA!


----------



## benny

Shut me down? ROFL

You're not worth my time, DMM boy


----------



## sparky3489

benny said:


> Nice midbass horn motor..... Shut me down? ROFL
> 
> You're not worth my time, DMM boy


Hell, you don't even know what kind of box it is. 

You've been shut down!!!!!

I've ALWAYS stated an o-scope is best but a DMM will work in a pinch.


----------



## benny

I know exactly what kind of box that is. It is a fourth order bandpass with a flared port. Suck it.


----------



## sparky3489

benny said:


> I know exactly what kind of box that is. It is a fourth order bandpass with a flared port. Suck it.


Close, it's a dual horn loaded band pass BUT YOU CALLED IT A midbass horn motor.


----------



## benny

Fail. It doesnt have nearly enough "horn" to be a horn. Horn motor maybe.


----------



## ChrisB

sparky3489 said:


> Not a thing wrong with those tutorials or that method of gain adjustment. It's better than by ear as a lot of people haven't a clue what they're even listening for.


You do realize that an amplifier will perform way differently when it is loaded down with a driver or dummy loads versus solely relying on the AC reading from the high impedance of the DMM, don't you? When it comes to clipping and solely using a DMM to set the output via the AC voltage reading, I have verified with an oscilloscope that clipping can/will occur much sooner once the amplifier is presented with a load!


----------



## sparky3489

benny said:


> Fail. It doesnt have nearly enough "horn" to be a horn. Horn motor maybe.


EPIC FAIL!!!

DECWARE's Wicked-One Horn Subwoofer


----------



## sparky3489

ChrisB said:


> You do realize that an amplifier will perform way differently when it is loaded down with a driver or dummy loads versus solely relying on the AC reading from the high impedance of the DMM, don't you? When it comes to clipping and solely using a DMM to set the output via the AC voltage reading, I have verified with an oscilloscope that clipping can/will occur much sooner once the amplifier is presented with a load!


Yeah, that's why I leave the speakers connected. To present a load.


----------



## ChrisB

sparky3489 said:


> Yeah, that's why I leave the speakers connected. To present a load.


Even this method can be a misnomer depending on impedance rise. I've had some try to tell me that their amplifier was grossly underrated because they were able to obtain way more voltage out of it when setting their gains via the DMM method while connected to the subs. They didn't take into consideration that their impedance had increased, therefore their amplifiers were NOT underrated.

If you really want to have some fun, try testing subwoofer amplifiers with a 20 Hz sine wave connected to subs or dummy loads while reading voltage and verifying the signal on an oscilloscope. The calculated RMS output between 20 Hz and 60 Hz with some amplifiers is a real eye opener!


----------



## benny

sparky3489 said:


> EPIC FAIL!!!
> 
> DECWARE's Wicked-One Horn Subwoofer


You think I've never looked at Steve's designs?


----------



## sparky3489

ChrisB said:


> Even this method can be a misnomer depending on impedance rise. I've had some try to tell me that their amplifier was grossly underrated because they were able to obtain way more voltage out of it when setting their gains via the DMM method while connected to the subs. They didn't take into consideration that their impedance had increased, therefore their amplifiers were NOT underrated.
> 
> If you really want to have some fun, try testing subwoofer amplifiers with a 20 Hz sine wave connected to subs or dummy loads while reading voltage and verifying the signal on an oscilloscope. The calculated RMS output between 20 Hz and 60 Hz with some amplifiers is a real eye opener!


HA ha, yeah I did that many moons ago just to see what happens.


----------



## sparky3489

benny said:


> You think I've never looked at Steve's designs?


So you don't think his design works in a mobile environment?


----------



## chad

sparky3489 said:


> Oh, I didn't know I was the Tylenol company!!!


Mother of god man, I had that ugly dude as my avatar for a while but i have not seen one that high-rez.. that's kickass.

And it's not horn loaded at sub-bass frequencies there for it cannot be called a horn... there's not enough mouth area, flip it sidewayes and point it into a corner Ala the K-Horn to get closer. 

Example, THIS HORN is only good to 63 cycles (Not subbass). and stands close to 5' tall and is 22" wide. 










Fortunately by stacking, the horn flares geometrically couple to decrease the cut-off frequency... 16 of those will make you **** blood at 20 cycles.


----------



## sparky3489

30 cycles


----------



## ErinH

Awesome... so what have we learned here?

That one person likes to set their gains differently. 
Can said person give a reason why using attenuated tones is worse than his method? Nope. 

Moral: Do what you want. You, the person reading this thread looking for information on how to set your amplifier's gains, are the deciding factor. You have the information and tools you need. Exercise with, dare I say, logical reasoning.


----------



## ErinH

sparky3489 said:


> I don't disagree with the method at all. *I just think it's a lot to go through just for car audio.* There's no chance in hell for car auidio to be as good as home audio (properly set up in both cases) so why go through all the trouble just to make an insignificant difference between methods?





sparky3489 said:


>



Define: Irony.


----------



## chad

bottom pic of the horns... those don't go very low either. They are even arrayed wrong.


----------



## sparky3489

bikinpunk said:


> Define: Irony.


Define: Confused.

:rolleyes2:


----------



## sparky3489

I'm just throwing pics out there that are interesting to me.










T-line tubes?


----------



## chad

No t-tine, that's just a well-done HUGE flare, very cool design. 5 bucks says that cat's not married :laugh:

My wife is pretty easy going and that WOULD NOT be acceptable by any means 

The one poured into the concrete is cool, I need to find that, another was one that went clear out to the guy's yard! Nuts I say, nuts.


----------



## sparky3489

I meant the black tubes at the back. I could swear those are huge assed T-Line.


----------



## chad

I believe they are, there's several threads around the net on them, possibly at DIYaudio?


----------



## thehatedguy

Those are Nelson Pass's speakers.

http://www.passdiy.com/pdf/KleinHorn.pdf

http://www.passdiy.com/pdf/KleinHorn2.pdf

http://www.passdiy.com/pdf/el-pipe-o.pdf



chad said:


> No t-tine, that's just a well-done HUGE flare, very cool design. 5 bucks says that cat's not married :laugh:


----------



## Oliver

sparky3489 said:


> So you don't think his design works in a mobile environment?


http://i68.photobucket.com/albums/i20/xargon_photos/sub-box-in-car.jpg



bikinpunk said:


> Define: Irony.


This guy is loved and heroed by 60nDown ^^^^ :surprised:


----------



## sparky3489

bikinpunk said:


> Define: Irony.


'Cuz I ALWAYS use my DMM/O-Scope to build boxes.'


----------



## scarface

wow...you guys are extremly serious about audio. from all of the info gathered...basically it is better to use a dmm by disconnecting your speakers and testing for the volts....seems like the safest way to me..considering im a newb to this stuff

i definetly would not like to try this using the sin wave and have my speakers blow up


----------



## chad

Everyone says use a DMM but then they forget how to factor in sensitivity and end up pissed because they have a system that will break plate glass from 3 miles.


----------



## scarface

chad...how would i figure out the volts needed? considering i use the kenwood kac-x4r amp 75rmsx4 @4 ohms my hu is a pioneer avh-p4100dvd


----------



## chad

put your DMM in the tool box.

Grab a well recorded CD you enjoy

Do it by ear

Little overall gain bumps to compensate on volume control position can be done quickly via trial and error as can balancing between passbands.


----------



## sparky3489

Umm, you won't blow your speakers using a sine wave. The sine wave is nothing more than a musical tone. Follow my guide and all will be well - Audio-Calc.xls - File Shared from Box.net - Free Online File Storage

It has had over 19,000 downloads and I get rave reviews on it. I would recommend however to find a 1KHz test tone that can be found here Realm of Excursion


----------



## chad

it's a musical tone with a duty cycle higher than any musical source.


----------



## sparky3489

umm, a 50% duty cycle?


----------



## scarface

thanks for the advice chad, apparently i found the owners manual for the amp online..the amp tells me when its clipping or not through the digital display it has )


----------



## sparky3489

A snapshot of the actual tone -









Musical tone if I ever saw one.


----------



## sparky3489

Oh and sensitivity is the amount of SPL or dB a particualr speaker will push with relation to the input power.

Speakers with higher sensitivity will push more SPL with less signal power.

Example for subwoofers:

Sub "A" is 1000 watts RMS/85dB
Sub "B" is 500 watts RMS/95dB

Sub "B" would actually be louder than sub "A" because the sensitvity is higher even though the power handling of sub "A" is higher.

This is how that works. The sensitivity of a sub is the SPL output the sub will have with 1 watt of power at 1 meter. For each doubling of power, you get a 3 dB gain in volume or SPL.

Power---Sub "A"--Sub "B"
1 watt = 85dB = 95dB
2 watts= 88dB = 98dB
4 watts = 91dB = 101dB
....
500 watts = 110dB = 120dB
...
1000 watts = 113dB = -------

Even at 1000 watts on Sub "A", Sub "B" still pushes more dB with only 500 watts.

This is only an example and actual dB output will most likely be higher as it all depends on many factors such as enclosure used, cabin gain, etc.


----------



## scarface

very well put sparky i appreciate the help iv never really looked at it that way, it surely helps shopping for subs


----------



## chad

sparky3489 said:


> umm, a 50% duty cycle?


With only a 3dB crest factor... I'm questioning your Media matrix training, I checked my lit I got and all of this was covered.


----------



## sparky3489

Correction:
"Speakers with higher sensitivity will push more SPL with less signal power."

Should have stated:

Speakers with higher sensitivity will push more SPL with less signal power than those with lower sensitivity of the same power handling.


----------



## sparky3489

chad said:


> With only a 3dB crest factor... I'm questioning your Media matrix training, I checked my lit I got and all of this was covered.


Which is normal for a 0dB musical tone.


----------



## chad

What?

Dude, srsly. I gotta give you credit, you have GREAT SPIRIT, a LOT of GREAT ideas... and absolutely no knowledge of sound system design or music. You have contradicted yourself multiple times and not even known it.

You are a dangerous individual that thinks the only driver in a car is the subwoofer.


----------



## sparky3489

I've never contradicted myself and I've been doing mobile/home audio for over 25 years. I was part of a team of technicians that installed 15,000 watts in the U.S. Cellular Coliseum which reqiured five racks of amps, EQs and DSPs and an enormous number of speakers of all sizes with miles of wire and cable.

My car has all components (NO coaxials) with my tweeters, mids, mid-bass and subs so I know very well all the drivers that make up a system. I ONLY gave an example about subs and that's what your basing your information on.

However, it is you with the issues and I'll list them:

ANY enclosure that has an opening (can be considered the port) larger than the throat is a horn. Whether it be a folded horn, conical horn, dual horn loaded band pass or what have you.

You didn't know the duty cycle of a wave form is the time difference between each half of the full cycle.

The sensitivity has NOTHING to do with setting the gain and in no way needs to be "factored in".

Setting the gain by ear is just about the worst way possible. There was a experiment where 15 pro audio shops were given the task to set a specific setup by ear. Only 2 had it set within tolerances of actual measurement. The other 13 had the system clipping while 3 of those had the system severely clipping.


----------



## chad

sparky3489 said:


> I've never contradicted myself and I've been doing mobile/home audio for over 25 years. My car has all components (NO coaxials) with my tweeters, mids, mid-bass and subs so I know very well all the drivers that make up a system. I ONLY gave an example about subs and that's what your basing your information on.
> 
> However, it is you with the issues and I'll list them:
> 
> ANY enclosure that has the opening (can be considered the port) larger than the throat is a horn. Whether it be a folded horn, conical horn or what have you.


The mouth of a horn depicts it's loading frequency, you are VERY correct, absolutely..., your "horn" is only a horn DOWN TO to around 500 cycles, way outside the passband your are playing at. For example a JBL 2380 loads to 800 cycles after, unfortunately that mouth gets larger and larger the lower you go, at a fast rate. So, you weren't wrong, it's a horn... just not in your application, which I depicted by saying that that flipping it on it's side, in a room, and using a corner for an extended flare would help it a lot or make it more of a horn. You forgot one thing... mouth loading and the true definition of a horn... below the loading of the mouth it's not acting as a horn.... period. You cannot argue that, it's well documented. The wacko in Peoria loads it quarter space and calls the floor a horn flare... which makes him 25% correct.




sparky3489 said:


> You didn't know the duty cycle of a wave form is the time difference between each half of the full cycle.


I ****ed up and Used the wrong terminology in haste, my dinner was ready, I'm even allowed to do that occasionally, crest factor... and no music has a crest factor as high as 3dB. If it did we would be in deep trouble, although we are fast approaching those boundaries with recluse abandon  you and I both know that a tweeter can handle a great amount of peak power, in contrast to the 5-10 watts it can handle for only a few seconds playing a sine wave.... You know this dude, I know you do, why do you act like you don't? Yep, it's tougher to blow a sub using a sine-wave... but you have to understand that most here are tuning multiple pass-bands where the more fragile drivers MUST be disconnected when testing with tones and the amp preferably loaded... not by the more fragile driver.



sparky3489 said:


> The sensitivity has NOTHING to do with setting the gain and in no way needs to be "factored in".


Why, lets hear this one...... it DOES NOT need to be factored in if you set the least sensitive passband first providing that in the subsequent passbands the amplifier power depicts that the drivers will play at or more than that of the least efficient passband with the given power available. Achieving a proper acoustic power response has EVERYTHING to do with sensitivity, this was also covered in your MM training. And this sir... is all of gain setting.



sparky3489 said:


> Setting the gain by ear is just about the worst way possible. There was a experiment where 15 pro audio shops were given the task to set a specific setup by ear. Only 2 had it set within tolerances of actual measurement. The other 13 had the system clipping while 3 had the system severely clipping.



So what is the tolerance of a gain setting? lets talk about this... by loading an amp and running it within an inch of it's life with a sine wave, to depict a worst case scenario, knowing full well that with music, that has a more respectable crest factor the amp will clip much later on peaks?

JUST LIKE I SAID, you have heart and principle... just a lot of mis-information... sometimes not mis-information, just half-assed.


Some of us have experience doing this AND can work a simple calculator... although, as I'm certain you will agree, it's amazing how difficult the car audio hobby makes it with their lack of standardization.


----------



## sparky3489

chad said:


> The mouth of a horn depicts it's loading frequency, you are VERY correct, absolutely..., your "horn" is only a horn DOWN TO to around 500 cycles, way outside the passband your are playing at. For example a JBL 2380 loads to 800 cycles after, unfortunately that mouth gets larger and larger the lower you go, at a fast rate. So, you weren't wrong, it's a horn... just not in your application, which I depicted by saying that that flipping it on it's side, in a room, and using a corner for an extended flare would help it a lot or make it more of a horn. You forgot one thing... mouth loading and the true definition of a horn... below the loading of the mouth it's not acting as a horn.... period. You cannot argue that, it's well documented. The wacko in Peoria loads it quarter space and calls the floor a horn flare... which makes him 25% correct.


25% is greater than 0% 

If it quacks like a duck, walks like a duck, tastes like a duck....it's chicken.





chad said:


> I ****ed up and Used the wrong terminology in haste, my dinner was ready, I'm even allowed to do that occasionally, crest factor... and no music has a crest factor as high as 3dB. If it did we would be in deep trouble, although we are fast approaching those boundaries with recluse abandon  you and I both know that a tweeter can handle a great amount of peak power, in contrast to the 5-10 watts it can handle for only a few seconds playing a sine wave.... You know this dude, I know you do, why do you act like you don't? Yep, it's tougher to blow a sub using a sine-wave... but you have to understand that most here are tuning multiple pass-bands where the more fragile drivers MUST be disconnected when testing with tones and the amp preferably loaded... not by the more fragile driver.


So where did you come up with a crest factor of 3dB?

A comparison of sine-wave to clipping. Some people believe the additional treble weighting is dangerous to tweeters. Others believe that it is not dangerous, noting that normal music recordings sometimes have significant treble energy and yet don't damage tweeters. 

NEVER did I say ANYWHERE on here to adjust the gain of ALL drivers together NOR did I EVER say to adjust unloaded.




chad said:


> Why, lets hear this one...... it DOES NOT need to be factored in if you set the least sensitive passband first providing that in the subsequent passbands the amplifier power depicts that the drivers will play at or more than that of the least efficient passband with the given power available. Achieving a proper acoustic power response has EVERYTHING to do with sensitivity, this was also covered in your MM training. And this sir... is all of gain setting.



See, your assuming that ALL speakers are amped. I'm assuming they're not. This is one of those cases we are both right and wrong depending on the circumstance.




chad said:


> So what is the tolerance of a gain setting? lets talk about this... by loading an amp and running it within an inch of it's life with a sine wave, to depict a worst case scenario, knowing full well that with music, that has a more respectable crest factor the amp will clip much later on peaks?.



You do realize there is music out there that will easily reach 3dB over. A 0dB sine-wave is a good starting point as it will actually result in better performance due to under-laping a bit. The structure of a sine-wave and an audio signal of the same magnitude has no difference. Out of the 19,000+ downloads of my guide, not one person has complained but I've had thousands rave on the best sound they could have ever gotten. So I did something right somewhere.





chad said:


> Some of us have experience doing this AND can work a simple calculator... although, as I'm certain you will agree, it's amazing how difficult the car audio hobby makes it with their lack of standardization.


We all have our own opinions.


----------



## chad

Most of us here are running fully active set-ups, in fact that's the goal of the place for most. That's why there's so many "full active" threads and threads on "bit ones, H701's, 9855's 9877, 9833, 9813's and 9815's, DRZ9255's eclipse active heads... etc.etc.etc.

you cannot go over 0dBFS. That's using all 16 bits right there, or 24, or 48 depending on format. When you record a sine wave at 0dBFS then that's the limit, music cannot digitally go over odBFS as per physics and redbook standards.

As for opinions, think about that, I'm sure we share the same one on this arena.... If car amps were set up with standards and labeled as pro audio amps were as the depiction of voltage gain and attenuation... and outputs were rated in standard dBU... damn... how cool would that be. Sure would make troubleshooting over the internet easier! 

*edit*
Oh sorry, crest factor, the crest factor of a sine wave is 3dB the crest factor of a square wave is 0dB


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## sparky3489

So how is it I can have music louder than the test-tone in the same frequency range?

So what are your thoughts on "carputers" with 7.1 Dolby, GPS, Wi-FI and such? The "ultimate ICE" as they say.



chad said:


> If car amps were set up with standards and labeled as pro audio amps were as the depiction of voltage gain and attenuation... and outputs were rated in standard dBU... damn... how cool would that be. Sure would make troubleshooting over the internet easier!
> 
> *edit*
> Oh sorry, crest factor, the crest factor of a sine wave is 3dB the crest factor of a square wave is 0dB


CEA-2006 compliance?

Even if the sine-wave is sampled from music?


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## buddhaV6

nice post. good to have something like this when i twiddle with my gains. and i could never put that process into words. i'm slow that way...

nice job!


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## benny

No, it's not a nice job, as a matter of fact, if you set your gains as suggested by "sparky", you won't be happy with the sound.


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## chad

sparky3489 said:


> So how is it I can have music louder than the test-tone in the same frequency range?
> 
> So what are your thoughts on "carputers" with 7.1 Dolby, GPS, Wi-FI and such? The "ultimate ICE" as they say.
> 
> 
> 
> CEA-2006 compliance?
> 
> Even if the sine-wave is sampled from music?


No, just standardization, just like pro audio **** has had standards since the 50's, said standards started in telco and broadcast and have matured to something absolutely wonderful. Interfacing is easy, level matching is easy, meters are cal'd the same... it's awesome.

To sample a sine wave from music you would need to look at a very pure source... for example when a string is plucked and observed on a scope it looks FAR from a pure sine wave, however when you hit a harmonic, on, say the 12th Fret of a guitar the waveform produced will be VERY sine wave-like... but still not perfect.


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## bertholomey

Very informative read - thanks Chad!


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## t3sn4f2

sparky3489 said:


> Umm, you won't blow your speakers using a sine wave. The sine wave is nothing more than a musical tone. Follow my guide and all will be well - Audio-Calc.xls - File Shared from Box.net - Free Online File Storage
> 
> It has had over 19,000 downloads and I get rave reviews on it. I would recommend however to find a 1KHz test tone that can be found here Realm of Excursion


It's not just a "_musical_ tone". What music has a fixed frequency full scale tone that continues on for seconds with no amplitude change? 

You aren't giving the voice coil ANY time to shed off the heat it is absorbing.

Also, since what is trying to be done is find the cleanest maximum output, that means that you have to go over he top at some time. What will that do to the already high 50% duty cycle of a clean tone?

http://http://upload.wikimedia.org/wikipedia/commons/0/0a/Synthesis_square.gif

A nice square wave.


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## scarface

ok so...here is the dillema....yall have confused the hell out of everyone "newbs" haha so now i dont know whether to use a dmm and how to find the correct voltage to set it right...or by ear .. here is my theory.....ready? ok..

i would prefer using the sin wave cd with a dmm and my highpass and frequencies selected. because: 
1. i cant damage the speakers
2.i wont have to go to any designated area to blast my music
3.it doesnt seem like a good idea to blast brand new speakers "not broken in"
4.theres a chance of blowing them.
5.not all music is teh same especially when you listen to a wide variety of music.

using the test tone and dmm you make a generalization of a fine tune (remember im a newb at this so correct me if im wrong) so my main question is this...

how do i figure out what reading should be on the dmm considering my frequencies are set on the amp. an oscilloscope would be perfect, BUT too expensive for a 2 minute job


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## sparky3489

benny said:


> No, it's not a nice job, as a matter of fact, if you set your gains as suggested by "sparky", you won't be happy with the sound.


(sigh) Can you just call yourself an idiot, I'm tired. Out of the 19,000+ downloads of my excel sheet, I've had nothing but praises and cheers from people that love the way their system sounds. NOT ONE cross email has ever gotten to me (and my email addy is right on the first page). 

To the rest:

It's simple. The purpose of the gain is to match the signal volts RMS coming from the source (CD player, etc.) to the input of the amp for correct power matching and to minmize clipping. Using a 0dB test tone is ideal for the fact that once you set the voltage correctly on the amp using the test tone, you are ensuring the gain is actually a little less sensitive which minimizes clipping under normal use.

Generating a perfect square wave is nearly impossible and in the most rarest of cases is extremely difficult to do unless you feed the amp a square wave. 

DMM/O-scope aside, if using a 0dB tone is so bad, then for the love of God PLEASE tell these people they are doing it WRONG - 

YouTube - Car Audio Gain Settings - Elemental Designs

http://www.youtube.com/watch?v=swg9HCfbbyU - Rockford Fosgate

http://www.youtube.com/watch?v=tQDEkxD8ed8 - Steve Meade

THE 360 CD BY ROCKFORD FOSGATE IS 0DB!!!!!!!!!!!!!!!!!!!!!!

...and what do you know, Steve Meade doesn't use a any load (not that I wouldn't)!!!!

An example of clipping -


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## chad

sparky3489 said:


> Using a 0dB test tone is ideal for the fact that once you set the voltage correctly on the amp using the test tone, you are ensuring the gain is actually a little less sensitive which minimizes clipping under normal use.
> 
> Generating a perfect square wave is nearly impossible and in the most rarest of cases is extremely difficult to do unless you feed the amp a square wave.
> 
> O-scope aside, if using a 0dB tone is so bad, then for the love of God PLEASE tell these people they are doing it WRONG -


I use 0dB too, but it's just the way I roll, I also ALLOW clipping in overlap by 3-5dB for recordings that need some help. But I also know my limits 

Some will use -3 to -5 tones to build this overlap, sometimes you need more, sometimes you need less. I prefer not to do it this way because I like to look at what's going on clear thru the chain and if the headunit clips early then you are not gonna see this with a tone other than at 0dBFS.

That being said, IF you set it without a load, the amp will clip due to power supply loading, the amount is dependent on load, if you set it so that it never clips with a tone, under load, then it WILL NEVER clip with music due to the fact that music is dynamic and the power supply has time to recoup... but I also find that this is wasting some available power you have purchased..... which is where some of my overlap comes in. A flickering of the clip light or very light clipping is not going to hurt ANYTHING, GROSS clipping, however, is not such a good thing 

Holy ****, did we just agree on something?


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## sparky3489

chad said:


> I use 0dB too, but it's just the way I roll, I also ALLOW clipping in overlap by 3-5dB for recordings that need some help. But I also know my limits
> 
> Some will use -3 to -5 tones to build this overlap, sometimes you need more, sometimes you need less. I prefer not to do it this way because I like to look at what's going on clear thru the chain and if the headunit clips early then you are not gonna see this with a tone other than at 0dBFS.
> 
> That being said, IF you set it without a load, the amp will clip due to power supply loading, the amount is dependent on load, if you set it so that it never clips with a tone, under load, then it WILL NEVER clip with music due to the fact that music is dynamic and the power supply has time to recoup... but I also find that this is wasting some available power you have purchased..... which is where some of my overlap comes in. A flickering of the clip light or very light clipping is not going to hurt ANYTHING, GROSS clipping, however, is not such a good thing
> 
> Holy ****, did we just agree on something?


Exactly!! You CANNOT eliminate clipping 100%.


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## chad

sparky3489 said:


> An example of clipping -


What's clipping in that image? Is that an amp or something line level?

You will see where I'm going, it's good.


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## sparky3489

It's from an amp.


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## chad

ouch, unloaded?


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## chad

Is a good pic to draw circles on. You may have heard me speak of overshoot when discussing clipping in a preamp chain and how it's not good. The bottom smaller circle is overshoot, this is one of the things (as described in th rane notes) that causes tweeter failure in clipping scenarios.










The upper circle, note how the trace is much thicker than the rest of the waveform on a scope that's damn well focused? That's oscillation, this HF content also destroys tweets and other low inductance devices. even though this is an amp and not a preamp it's a great example as to what goes on. I have seen speakers driven by an amp that never clipped get destroyed by obvious UHF information and clipping, the amp never clipped but it did a damn good job of amplifying everything in front of it that was clipped to hell.

The reason I asked if it was loaded or unloaded is because an unloaded amp is generally much more likely to exhibit this trait, especially in overshoot whereas a loaded amp does not. Preamp overshoot is often worse. if you are running multiple gain stages and the gains are all over the place it's a good idea to look into this.


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## sparky3489

A.K.A. ringing


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## MarkZ

Know why it's stupid to set gains to 0dB sine waves?

Because sometimes I like to listen to this song loud.


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## chad

sparky3489 said:


> A.K.A. ringing


yeah, kinda, when you hear a ring the top and bottom is so grossly clipped that it will no longer flatten out but DIP back down(or up ont he bottom,) bad news another thing you will hear at this point is crossover distortion when really stressed, that dog leg at the zero cross that's not present here.. We actually dial in a little dog-leg in biasing a tube guitar amp when under stress, makes it sound better. You won't hear a ring there over the original tone as much as more of a square wave as that's well into ultrasonics.. which is why I used that.

Some people will call straight clipping ringing but if you modulate a square wave, a clean one in with the sine wave or even mix some low level square wave, in phase it will sound very much the same. So I guess if you wanna call it "ringing," fine, but real ringing is flat out ugly.


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## sparky3489

MarkZ said:


> Know why it's stupid to set gains to 0dB sine waves?
> 
> Because sometimes I like to listen to this song loud.


Bully for you!


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## MarkZ

sparky3489 said:


> Bully for you!


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## sparky3489

MarkZ said:


>



Some like loud music, others like music.

It's all good!

epper::drummer:epper:


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## iamjyoung

Couple of ??

1. Do you have a similar SS for setting up speakers? This seems to be for subs only. 
2. I would assume you should set the gain with a load on it. How does the amp know whether it is a 2 or 4 ohm load? Also, not all speakers are exactly 4 ohms?
3. Does it matter if the car is off or on? The battery will output 12.6 volts at best while the charging system will up the voltage to 13.8+ . . . so this means the system will clip sooner with car on if you set up with battery?


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## caraudioguru

Set up is the same. Subs are the easiest as they typically have way more power. So the real limiting factor is the mids and highs from clipping standpoint anyway.

Load? Yes if you just happen to have a 1,000 watt DALE 4 ohm load resistor, yes this would be better. My guess is that 99% of the guys out there don't have that just laying around (we do, but we should!!) And today's amps are very good so having them unloaded won't really make much of a difference (remember I have done this a thousand times!!) so I know it works. have faith 

And voltage doesn't make much difference (9% to be exact) So 100 watts versus 109? you wont here a difference unless it is much greater, at least at low frequencies. But run your car and test that way if it makes you feel better. I do it both ways.

Just get the CD104 from AutoSound 2000 its a great disc to have for testing.


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## sparky3489

iamjyoung said:


> Couple of ??
> 
> 1. Do you have a similar SS for setting up speakers? This seems to be for subs only.
> 2. I would assume you should set the gain with a load on it. How does the amp know whether it is a 2 or 4 ohm load? Also, not all speakers are exactly 4 ohms?
> 3. Does it matter if the car is off or on? The battery will output 12.6 volts at best while the charging system will up the voltage to 13.8+ . . . so this means the system will clip sooner with car on if you set up with battery?


Take the square root of (watts X ohms) to get volts.

You can get a 1KHz tone form here Realm of Excursion

A load is best. The ohms of the speaker is what determines the load on the amp. No, speakers are not exactly 4 ohm, but it's standard to say 2 ohm or 4 ohm even though it may be 1.8 ohm or 3.6 ohm. The impedance (ohms) change with frequency.

Set the gain with the car on as this will be the typical scenario for the system.


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## chad

You are aware that if you use decent software, such as soundforge in simple synthesis, that you can zip a HUGE wave file of a tone and it will take up like a few hundred KB right? 

May be a cool addition to your site


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## sparky3489

If I just ZIP the file it's size is reduced by half.


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## chad

No, I'm talking a HUGE file reduced to nothing.. want me to e-mail you one as an example?

I'll need to find it but shoot me an e-mail thru here and it's DAMN amazing. You just have to make it a PURE sine, not record a sine, Pure Simple synthesis in software.


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## chad

MEGAUPLOAD - The leading online storage and file delivery service

There, check that out.. cool ****.


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## chad

So for KB's of storage you can do 1/3 octave PURE tones on little to no server space... unfortunately the have to be simple tones, have not tried square waves yet.

Pink noise is a big no on compact storage.


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## sparky3489

Nifty


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## chad

sparky3489 said:


> Nifty


No ****, blew my mind, thought I made a mistake... zipped them 3 times 

I'm thinking of doing 1/3 octave tones to post up.. dunno how long each but if you have input I'll certainly share.


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## sparky3489

I would think 30 seconds or a minute each should suffice.


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## chad

may do longer just to get to the trunk and back for fat people like me 

It's only kilobites


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## sparky3489

That's what repeat is for


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## chad

I don't even know if my head unit has repeat :blush:


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## sparky3489

No remote? LOL


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## chad

sparky3489 said:


> No remote? LOL


The remote stays with the test rig for the most part, I refuse to use it in th car.


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## coronamike

I've tried to set my gains many different ways and have determined that no matter what I do it sounds like crap. Time to change equipment.

lol


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## sparky3489

Does your equipment match to some degree? Power, impedances, etc.

Are your subs in the right box?


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## coronamike

I'm using a Alpine PDX-4.150 to push CDT TW-25S tweeters and CL-6CF Mids, passive.

I have an Alpine PDX-1.600 to push a single TC Sounds TC-1000 10" Sub in a sealed box built to specs.

Fully damped trunk and doors with second skin. All this stuff is in a 2005 Acura TL.


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## sparky3489

Sounds like s sweet system. 

Try setting the gain on the PDX-4.150 with a 1KHz tone and the sub with a 40Hz tone.


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## JayinMI

I'm not going to go back and count them, but I think all of Sparky's 64 posts are in this thread.

And most of them are random or argumentative, and have no real bearing on the original topic.

After reading 7 pages of replies, I've found I should look elsewhere.

Jay


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## sparky3489

On random posts and off topic!

Hello, kettle, you're black!


Being argumentitive is simple defense.

Please, by all accounts look elswhere, we don't want you here.


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## dantonel

spmpdr said:


> So a good way to think of this is a 10 yr old jumping on a bed - that's the music signal. The bed is the amp's RMS power, the ceiling above is the headroom limit. If the kid jumps too high he whacks his head - that's clipping. Do it a couple times & he'll survive. Do it repeatedly & there WILL be permanant damage.


I literally laughed out loud at the mental picture of some dumb kid repeatedly hitting his head on the ceiling! LMAO-ROF-LOL

All in all though a very insightful and worthwhile how to.


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## littlejuanito

My Eclipse CD5030 has volume level adjustment for each Source. Where should this level adjustment in the unit be set at when setting up my gains at the amp. Should I max it at the unit?


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