# RTA Tuning: What works best for me.



## ErinH

This is what I’ve learned works best for me when using the RTA to tune. This may or may not work for you. This is simply a suggestion on how to tackle something that otherwise is a bit daunting. 

You really need to be active, or have a way of controlling each ‘channel’’s gain/level separately for this to work well. 


*I’m going to assume you know how to set t/a and x-overs. This is for EQ/levels work with the RTA ONLY.*


*1.* First off: *Write all settings down, then reset your DSP/headunit.* This is pretty self explanatory. You want to zero out all settings and start from scratch. But, you also need to note some of the basics that worked before, such as time alignment, phase and crossovers. 

Enter your desired crossover points; I’m assuming you know what points work best for you. 

*2. Set your amp gains to the max desired output.*. Whether you want to use an oscope, or DMM with 0db, -3db, -5db, etc tones, that’s of no concern to me. This is your amp and your system. You decide what you want to do. If you want to sit in the car while someone adjusts them for you, that’s fine. But make sure you mark somehow what your ‘don’t go past this point’ limit is. You need to state to yourself the maximum gain you want to use.

*3. Now, pull out the RTA.* 
*******If you have a program that allows for a-weighting I HIGHLY suggest using this instead of C-weighting or no weighting. It’s my personal preference. If you want to know what the difference is, here:
http://www.diymobileaudio.com/forum...ing-loudness-curve.html?highlight=a-weighting

In a nutshell, a-weighting is a weighted curve for how you actually hear things. It takes less power/loudness for you to hear higher frequencies than it does lower frequencies. The a-weighted curve adjusts for this automatically. C-weighted ‘sort of’ does, but not like a-weighting. **********

*4. With the RTA setup play each side (left/right) SEPARATELY.* DO NOT play the entire system together. Your goal here is to level match left and right. To me, this is the single most valuable tool the RTA has the ability to do. Use pink noise or sweeps; whichever you prefer. I use pink noise mainly, but IME sweeps work well. It’s all dependent on the software you use. Kick the headunit volume up to the level at which you would rock out to (where your gains are set to for max output). I say to do this because I typically only listen to music when it’s wailing. Also, if you don’t, you have to realize that the loudness curve (which I linked discussion about above) will be changing for each incremental volume you make; so your settings for ‘loud as crap’ may not be the same as for ‘my neighbors live in my car’ (aka: low volume). So, set this up as you would typically listen. 

*5.* Now, when level matching everything you should go down the line; and what I’ve found works best is to *start with the best link*. 
You know that you have 2 drivers up front and you know the band they cover. Obviously you’re not going to start off with a flat line right off the bat, BUT you AT LEAST KNOW where your speakers play up/down to. Use this knowledge to level match the speakers on the same side. 
I start with the ‘strongest’ link (the speaker that’s at the highest level). I do this for one reason: you’ve maxed your gains; you don’t want to max them anymore. So, if the tweeter is playing a bit higher than the midrange, knock the tweeter down. 
*If your tweeter rolls off pretty badly*, what *I’ve found* works well is instead of knocking down the entire tweeter level, just knock down the portion that plays higher than the rest of the tweeter. For example, your tweeter plays from 3k-20k, but it rolls off hard at 16k. Knock down 3k-16k via EQ (but don’t worry about flattening it yet) so that you can level out the tweeter itself. You can also do this for the midrange/midbass, too, but typically, I don’t trust the RTA below 100hz for accuracy. I typically do this by feel/hear. 

*6. *Once you’ve leveled out the tweeter roughly, try to level match the tweeter/mid together the best you can. Try to make that line as flat as possible using the gain and the EQ. 
Once you’ve gotten as flat a line as you can (I don’t know what kind of processing you have), write down the level. The level may be 40dB on the RTA software, for example. THIS IS IMPORTANT so you can level match the other side to the same point. Otherwise, all the work you’re doing for level matching is pointless. 
*To flatten out the results, I suggest picking a point that seems to be a good middle ground for your current graphical response. Then, start at 100hz and go up to 20khz, making adjustments as needed. I HIGHLY suggest NOT doing any boosts in the EQ. Only use cuts if at all possible. Keep in mind a boost could put you into a higher ‘gain’ than you wanted.*

*7. *After you’ve level matched one side, and written down the level… do the other side. Same way. Start with the speaker playing at the highest level and match that to the one that’s playing at the lowest level. Flatten out the graph via your EQ the best you can.

Now, you’ve really gotten about 90% of the RTA work done. Congrats! You should have a very balanced system right now.

*8. *Now, you want to sum the response by playing both sides at the same time and check the EQ. You’re NO LONGER DOING LEVEL MATCHING here. You’ve already matched the two sides. You simply want to EQ for flat at this point with a summed system response. You really shouldn’t have to do much work here. 

*9. **After you’ve level matched individual sides and flattened the total system response* get back in and LISTEN. Use the RTA to your advantage. Play reference tracks and see what doesn’t sound right to you. The RTA can help pinpoint frequencies if you don’t know right away. Also, you’ll no doubt have to toy around a bit with time alignment. You shouldn’t have to touch phasing, though. Truthfully, t/a shouldn’t require much adjusting at all, but there will likely be some small adjustments needed. 


That’s it. I know I’m forgetting things, but hopefully I can edit this later and add them. Sorry for the long post. I tried my best to keep it short and sweet. 




NOTE: I realize there’s a LOT of subjectivity here. I really don’t want to hear all of it in this thread, as most of us are smart enough to realize the pitfalls of tuning to flat or anything I’ve said. Nothing is perfect. I’m only posting to provide what I’ve found works well for me. I don’t expect everyone to agree, really. But, I ask that you try it before you discount it completely. If you have suggestions, I’m all for learning. 

Thanks,
Erin


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## doitor

GREAT contribution, Erin.

Jorge.


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## braves6117

Nice Job Erin. I appreciate the time spent, well done.


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## ErinH

Glad I could contribute something here. 

If anyone has questions/comments please throw them out there. But, as I said, I'm not really for arguing the above. I just wanted to share what works well for me.


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## 30something

Thanks for sharing your experience.

Things sure have changed from 4 - 5 years ago (the last time I dabbled in mobile audio)...to think that all I need is my laptop and a couple hundred bucks and *poof* I've got an RTA... looks like I can finally throw away my RadioShack SPL meter and graph paper!


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## michaelsil1

I've found that if the sensitivity is raised it's easier to read frequencies below 100Hz.


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## ErinH

It's not that I have a problem reading it, it's just that to truly get the low midbass frequencies to measure flat often takes some work, and when you get in and listen my experience has been that it's not too great. So, now I just tune 80hz and below by ear. I said 100hz is the cutoff point, but that's mainly due to flattening it out. 

What sensitivity are you talking about? RTA program sensitivity or... ? 

Thanks for the feedback.


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## michaelsil1

bikinpunk said:


> It's not that I have a problem reading it, it's just that to truly get the low midbass frequencies to measure flat often takes some work, and when you get in and listen my experience has been that it's not too great. So, now I just tune 80hz and below by ear. I said 100hz is the cutoff point, but that's mainly due to flattening it out.
> 
> What sensitivity are you talking about? RTA program sensitivity or... ?
> 
> Thanks for the feedback.


RTA sensitivity: Change the first line from 20db to 10db or lower.


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## ErinH

Gotcha. Didn't know what you meant.


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## aztec1

Thanks for taking the time to write this up, it should prove to be helpful for sure. I find that some horn instruments change sides as they change pitch in my system, it's really annoying!

A few noob questions, hope you don't mind: 

1: Do you put the mic at your listening position, or in the middle?
2: In step 8, you say to EQ flat for the summed system response. What could cause the response to be different? 
3: Why only recommend cutting on the EQ? Does it do something to the sound? I've found I don't hear as well as I used above about 12K, if i boost frequencies above that, will it color the music?

I realize most of the above is subjective and dependent on a lot of things, I just want to know what you think.

Cheers!


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## ErinH

aztec1 said:


> 1: Do you put the mic at your listening position, or in the middle?
> 2: In step 8, you say to EQ flat for the summed system response. What could cause the response to be different?
> 3: Why only recommend cutting on the EQ? Does it do something to the sound? I've found I don't hear as well as I used above about 12K, if i boost frequencies above that, will it color the music?


1. I put it on my headrest in the driver's seat. 
2. You'd be surprised what happens when you sum the system. I can't explain how/why it happens, but it does. Though, very slightly. Last time I did the rounds, there were about 4 bands that needed to be adjusted a bit.
3. When you boost, it's the equivalent of adding more gain. Remember, I suggested setting gains to max before you do anything. That is why; if you boost anymore you could possibly drive your level up to a 'gain' where you wouldn't want it to be.


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## braves6117

bikinpunk said:


> 3. When you boost, it's the equivalent of adding more gain. Remember, I suggested setting gains to max before you do anything. That is why; if you boost anymore you could possibly drive your level up to a 'gain' where you wouldn't want it to be.



Great tip! I didn't think of it that way at all. 


Although some may think it's not practical, I love having relationships regarding how to think about things. It just makes it, well, easier for me.


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## ErinH

It's kind of a rule of thumb. Don't think you won't see boosted points on my EQ, but I try to keep it as minimal as possible. 

If you wanted to do the math, you could get an idea of how much boosting a couple dbs would equate to power and you could probably figure out how much clipping you're introducting at this exact frequency. I don't care to do that, myself, though, lol.


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## michaelsil1

bikinpunk said:


> It's kind of a rule of thumb. Don't think you won't see boosted points on my EQ, but I try to keep it as minimal as possible.
> 
> If you wanted to do the math, you could get an idea of how much boosting a couple dbs would equate to power and you could probably figure out how much clipping you're introducting at this exact frequency. I don't care to do that, myself, though, lol.


Chad says think outside of the box; a dip could be expressed as two peaks.


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## ErinH

I trust Chad.


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## kevin k.

I'd be interested in the measured low frequency values you end up with after tailoring A-Weighting to suit your tastes, Erin. To be in the neighborhood of a 'flat' A-Weighted response aren't you going to up end around +30 db at 50 Hz and approx. +50 db when referenced to the 1 kHz db value...? That's a ton of power required... yikes! 

With 'plain old' B-Weighting, for example, it still takes a lot of power to come up a +12 db at 50 Hz and approx. +24 db at 20 Hz when referenced to a specific 1 kHz value..

I'm just wondering what actual values you end up with when you do tune those lower frequencies (even just the 50 Hz value would be interesting) by ear and if they end up being near as high as the numbers listed above...?

Thanks!


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## ErinH

I honestly don't think I'd be able to get those numbers anytime soon.

I guess my real point is that the aweighting extends all the way up to even 500hz and beyond. C response doesn't curve until 100hz. I believe the difference I am benefiting from in my trial and errors is from this. Now, while I may not be tailoring it to a ‘t’ sub-100hz, the effectivity isn’t just in that range. You also get the added benefit of leveling off the lower end frequencies. C and B, for me, just haven’t worked as well. I realize the difference and power requirements. As I said above, I typically do 100hz and below by ear… maybe that’s why.


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## kevin k.

If you do have the time or opportunity to get them, I'd be interested to see how close they are in the lower registers to the spec'ed numbers. Never really looked closely at what A-Weighting would require... looks like 500 Hz would be about +4 db and 200 Hz about +11 db relative to a 1 kHz reference. What do you mean when you say you get the added benefit of leveling off the lower frequencies? Sorry, but I'm not following you... 

Thanks for sharing this stuff, Erin... pretty interesting.


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## ErinH

I guess I’m having a hard time putting into words what I’m trying to say. :/

‘the added benefit’ being that C doesn’t tailor to what we hear as well as A does. The added benefit there (at least, to my ears) has been you’re then accommodating for even 500hz rather than just sub 100hz.

Does that make more sense?

I’m a long shot from a pro at this, which is why I posted the ‘what works for me’.  
But, I’m always open to questions and suggestions; otherwise I won’t force myself to learn. Chad introduced me to A weighting and since I used it a few months ago, it's pretty much been my go to.
Thanks, Kevin.


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## michaelsil1

George (cvjoint) has been very supportive; he says we're in an area that very few venture so be patient and experiment.


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## ErinH

^ I don't really get what you're saying?

Are you talking with George on the side? 

Me =


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## kevin k.

I see you lurking Chad... 

Would you comment, please? 

C'mon! Out with the goods!


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## michaelsil1

bikinpunk said:


> I’m a long shot from a pro at this.






I was referring to the frustration of none of us being an expert and what's wrong with talking with George :scholar: he's the only one I know that was willing to tackle and Tune a five way active system.


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## Blackfox

Very Informative, thanks for the info.


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## aztec1

This procedure actually showed me that my tweeter amp had a problem in the bridged rear channels. I couldn't get my left speaker to match my right one, no matter what I tried. Very frustrating! Going all the way back to the amp, I was able to find that the rear gain pot has a bad spot in it. After spraying some contact cleaner in there, I set it to a stable level and matched the front pot gain to it instead of vice-versa and was able to get the tweeter sounding to my liking.

So on top of tuning, this has proven to be a valuable troubleshooting tool. Thanks again for sharing this info, it's really helped out my sound ALOT!


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## rockinridgeline

Great post!. I would just add for anyone who is kind new to car audio, if you are going full active crossovers on your system, be very careful. While your sub won't care if you high pass the signal to it, sending a full range signal to your tweeters at 90% volume will probably fry them. Double check your crossover settings and channels before cranking it up the first time.


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## michaelsil1

rockinridgeline said:


> Great post!. I would just add for anyone who is kind new to car audio, if you are going full active crossovers on your system, be very careful. While your sub won't care if you high pass the signal to it, sending a full range signal to your tweeters at 90% volume will probably fry them. Double check your crossover settings and channels before cranking it up the first time.


I would think that sending a full range signal to a Tweeter would sound terrible and getting to 90% volume on them you deserve :toilet:


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## rockinridgeline

I worked in high end 12V for 5 years and saw a lot of guys do that sort of thing. Just wanted to make sure that a noob understood that when you remove the passive crossovers your mids and tweets are unprotected. Best advise would be to put a cap on the tweet that ensures against this but crosses it over well below its typical crossover point. Even really careful experienced installers screw up every now and then.


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## Mag1c Carp3t

How to achieve step 8 using helix software. I don't see a Master EQ like my mObridge had?

"8. Now, you want to sum the response by playing both sides at the same time and check the EQ. You’re NO LONGER DOING LEVEL MATCHING here. You’ve already matched the two sides. You simply want to EQ for flat at this point with a summed system response. You really shouldn’t have to do much work here. "


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## dumdum

Mag1c Carp3t said:


> How to achieve step 8 using helix software. I don't see a Master EQ like my mObridge had?
> 
> "8. Now, you want to sum the response by playing both sides at the same time and check the EQ. You’re NO LONGER DOING LEVEL MATCHING here. You’ve already matched the two sides. You simply want to EQ for flat at this point with a summed system response. You really shouldn’t have to do much work here. "


Take an equal amount from both sides using a spare parametric eq band with the two channels joined together

Or if you have a helix with virtual channels use that as that is a true global eq 👍🏼


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## Mag1c Carp3t

dumdum said:


> Take an equal amount from both sides using a spare parametric eq band with the two channels joined together
> 
> Or if you have a helix with virtual channels use that as that is a true global eq 👍🏼


Ok will do. I am running active so I will join all 4 channels and essentially re EQ to the JBL curve.

One issue I've ran into using A weight is I cant achieve target dB's below 200hz. When I max out my EQ bands on the channels below 200hz they are overly powered when playing. I think I may need to switch back to no weight.

Starting to wish I waited for the P SIX mk3 with virtual channels.


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## dumdum

Mag1c Carp3t said:


> Ok will do. I am running active so I will join all 4 channels and essentially re EQ to the JBL curve.
> 
> One issue I've ran into using A weight is I cant achieve target dB's below 200hz. When I max out my EQ bands on the channels below 200hz they are overly powered when playing. I think I may need to switch back to no weight.
> 
> Starting to wish I waited for the P SIX mk3 with virtual channels.


Tbh I use rta in rew and the spl setting with 1/48 octave and then apply variable smoothing once I have saved the original to see the phase related dips as we need less smoothing at low freqs vs high freqs and variable works quite well for this


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## Mag1c Carp3t

I use an Audiocontrol S400I iPhone mic and only have access to their app. The app uses 1/3 octave with no weight, a weight and c weight options.


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## dumdum

C weighted then for me measuring a car


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## Mag1c Carp3t

dumdum said:


> C weighted then for me measuring a car


I'll try c weight next and see how it sounds.


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## KillerBox

Just to be clear, we should be using C weight to measure a vehicle?


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## Mag1c Carp3t

Reporting back. I was able to hit my target curve using Flat SPL with exception to 20k Hz, C-Wtd SPL seemed to have similar results as Flat SPL, will need to verify again. The music is too bright for my taste. I somewhat preferred what A-Wtd SPL sounded. I may need to go for a hybrid approach and utilize the A-Wtd SPL again but not boost my lower frequencies (my speakers are below max gain).


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## dumdum

Mag1c Carp3t said:


> Reporting back. I was able to hit my target curve using Flat SPL with exception to 20k Hz, C-Wtd SPL seemed to have similar results as Flat SPL, will need to verify again. The music is too bright for my taste. I somewhat preferred what A-Wtd SPL sounded. I may need to go for a hybrid approach and utilize the A-Wtd SPL again but not boost my lower frequencies (my speakers are below max gain).


That’s just your house curve that’s wrong for your listening preferences, adjust it and make it more to your taste 👍🏼

Do you mean you tuned the stereo to a flat house curve? If so that’s why it sounds bright, never ever tune flat, it’s a car and we expect to hear more bass due to the nearfield environment and the enclosed space


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## Mag1c Carp3t

dumdum said:


> That’s just your house curve that’s wrong for your listening preferences, adjust it and make it more to your taste 👍🏼
> 
> Do you mean you tuned the stereo to a flat house curve? If so that’s why it sounds bright, never ever tune flat, it’s a car and we expect to hear more bass due to the nearfield environment and the enclosed space


No, I was able hit this curve minus the 20k HZ using the Flat SPL weight, which I verified last night is the same as C-Wtd SPL. I'm thinking I should RTA my base tune, write down the dB's , create a new chart and level match and EQ to that curve since to me it sounds great.


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## Mag1c Carp3t

I redid my tune using Flat SPL weight again, but with no boosting, and found better results. I also utilized Audiofrogs curve, though I am uncertain why it's not truly flat in the center from 200 Hz+. Do we try to match this or do we go for a more flat target curve ex. 70 dB 200 HZ-3.2k Hz?


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## dumdum

Mag1c Carp3t said:


> I redid my tune using Flat SPL weight again, but with no boosting, and found better results. I also utilized Audiofrogs curve, though I am uncertain why it's not truly flat in the center from 200 Hz+. Do we try to match this or do we go for a more flat target curve ex. 70 dB 200 HZ-3.2k Hz?
> 
> View attachment 322304


I find the audiofrog curve very light in the sub bass, I aim for an upward rise from 250ish to 20hz of approx 15db, 6db sounds thin and lacking any energy to me

And roughly flat through the mid range, don’t over obsess with getting it mega flat, narrow deep dips will pull down 1/3 or 1/6 octave bands, but when you look in more resolution everything around the dip can be flat, but if you only looked in 1/3 octave for instance you may boost that band and think it’s great, until you listen and find it sounds peaky I am happy with +/- 2db resolution and go from there


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## Mag1c Carp3t

For the sub bass I ignore the chart and have it set to max gain. 63 Hz and 125 Hz are my only dips, I think by 5 dB's. I also noticed the sound moved slightly to the passenger side. I am going to center my mic in between the two front seats and see if I prefer that, considering my base tune sounds balanced to me with no level matching.


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