# Gain Setting, Matching, and Tuning on an Active Setup



## rton20s (Feb 14, 2011)

Not that I have anything installed yet, but I wanted to get opinions on how to set/match my gains as well as tune my system once it is in. I wouldn’t even bother posting a thread like this, but there seem to be a ton of differing opinions on DIYMA when you do a search. On all of my (simpler) previous systems, I have set my gains by ear. With as much control as I’ll have now, I thought it might be time to step it up a bit. 

Head Unit: Pioneer DEH-80PRS (Active Mode)
Amplifier: Arc Audio KS900.6 (60W x 4 @ 4 Ohms + 550W x 1 (bridged) @ 4 Ohms)
Front Tweeters: Hybrid Audio Technologies Imagine I1
Front Mids: Hybrid Audio Technologies Imagine I61-2
Subwoofer: Hybrid Audio Technologies Imagine I10SW

The plan is to skip the amp’s crossovers all together and only use the head units active crossover. Initial crossover settings will be set prior to running through the gains and subsequent tuning. I would also like to use the Auto TA/EQ at least for initial settings to further tweak. 

I have access to an O-Scope as well as a DMM. So my initial plan was to set the gains with these. Run 0dB test tones in the appropriate frequency range for each channel with everything on the head unit set dead flat and the RBK for the sub at full tilt. With each channel having its own gain, would I then want to match the voltage of the two tweeter gains to each other? Same for the mids? 

If I set everything this way, all of my tuning at the HU, should then be subtractive, correct? And running Auto TA/EQ could put some channels into clipping? So if I ran these, I would have to go in and check the settings adjust them manually as necessary to prevent this? 

Any other recommendations you might have? Perhaps a different sequencing or technique, given the flexibility I would have with the system? 

Thanks, and I look forward to your responses.


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## MarkZ (Dec 5, 2005)

rton20s said:


> If I set everything this way, all of my tuning at the HU, should then be subtractive, correct? And running Auto TA/EQ could put some channels into clipping? So if I ran these, I would have to go in and check the settings adjust them manually as necessary to prevent this?


This has been expanded on in a number of threads here. So I won't elaborate too much. But you need to think about what happens when you listen to a track whose peaks are less than 0dB. When that's the case, you'll never realize the full potential of the amplifier. This is one reason why combination preamp/amplifiers usually begin to clip with typical program material when the volume knob is around 1 o'clock (or less). The manufacturers know that they need to be able to play an assortment of musical selections.

Some people prefer to use -3dB tones instead of 0dB. Or -1dB. Or -6dB. You get the idea.  Given that the choice of reference level is _completely _arbitrary, I choose not to haul the scope outside for setting gains. Why use precision to measure something that's inherently not precise?

I'm not familiar with the capabilities of your HU, but I think the best procedure, generally, is to do T/A first, then levels, crossovers, and EQ together. Those three things all rely on each other, whereas T/A is its own independent signal manipulation (assuming you're using it to equalize arrival times, and not some other goal).


Edit: Regarding precision in setting gains... I should point out that gain setting should not be used to do what a limiter is designed to do. _They're not the same thing._ The gain control is basically a volume knob that calibrates source and target. A limiter, on the other hand, dynamically reduces the level to prevent clipping, while accommodating different sources. IIRC, McIntosh offers a limiter built into some of their amps. Other manufacturers might offer it in signal processors... in which case, precise measurements _could_ become useful.


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## vwjmkv (Apr 23, 2011)

i could some help here too please. i have the following equipment: 

JL 300/4 v2 Slash bridged powering front mid bass

JL 300/4 v2 Slash powering midrange and tweeters passive up front and rear comp passive

JL 750HD powering JL W6 v2

i still need a DSP
what is the appropriate tuning process?

CC


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## hpilot2004 (Dec 13, 2011)

Usually I set my h/u to 70% of max volume, which on my h/u is 26 out of 35. Then I just use my ear to tune my one amp, it's an Arc 900.6 as well. I don't have multiple amps, but I also have a RF360.2 for processing purposes. It always worked for me, but I don't get to technical about it.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

http://www.diymobileaudio.com/forum...bers/33149-mini-tuning-guide-active-user.html


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## rton20s (Feb 14, 2011)

OK, so I have read through all of the responses, as well as the “Mini Tuning Guide for the Active User” thread. I’d read it before, but it was a good refresher. 

In terms of setting gains with test tones, etc. is it actually preferred to use -3dB because we typically aren’t listening to our music maxed out? We would then see more from the amp on a day to day basis. But at those times that we are pushing it and we have the volume up and we actually hit those 0dB levels we would push the system into clipping, even if only for a brief moment? 

As I understand it, using 0 dB test tones with an o-scope to check for clipping means you’re tuning the system to be as close to 100% “safe” as possible. However, in doing so you’ll rarely, if ever, reach the amps full potential. As you move into negative dB test tones (-3, -6, etc.) you’ll be seeing more of your amps potential while increasing risk of clipping at peaks in the music. The further into the negative the dB, the more risk you’ll run. I would guess that -3 dB a fairly safe bet for a daily driver system that won’t often be pushed to the limit? 

Then, after setting each of the gains individually, would it be best to attempt to level match each speaker reducing the gain on any that were high? (Either by ear, with a DMM, or a combination of the two.) Primarily, so that less of this has to take place in the digital processing? Or would you just leave all of the gains “as is” and attempt to do all level matching digitally with the DEH-80PRS on-board processor? 

I’ve also heard the rule of thumb of setting the gains with the head unit at ¾ volume (or 70% as hpilot2004 mentioned). Would you do this in lieu of using a -3dB test tone? Or is this done because you feel safer limiting yourself to ¾ volume to prevent clipping at the HU? Couldn’t you just test the HU for clipping to find out what your real maximum volume should be? (If the case is the former and not the later.) 

I’m just really getting anxious! I really want to get this gear installed. Still need to order up my sound deadener and amp kit/wiring.


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## jtaudioacc (Apr 6, 2010)

I'd just figure out where the head unit clips, then go from there. I'm gonna guess it doesn't clip, flat, with SLA at zero.

I'd even use -10db tones, but just so you know you start with a level gain structure. Of course not all music is mastered at 0db. O-scope is great to have to figure some stuff out but a lot of guys take it too seriously with gain adjustments.


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## hpilot2004 (Dec 13, 2011)

Go to HAT's website, they give vast information about setting up that component set actively or else call them and get tips on this set up. They are an outstanding company from what I have heard. I always tend to run the h/u at a lower volume just to be safe. Every component has different noise issues, how one overcomes them is basically with a little experimentation. I would get the deadning mat ordered and run your wiring first, run all of your RCA's from the deck even if you don't use them all (it's nice to have them ran close to the amp for future use.) Take your time to deaden the vehicle, most gains from this aspect for your door speakers. Buy good quality RCA's and speaker wire for all components in your set up and you should be well on your way to a great sounding system!


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## hpilot2004 (Dec 13, 2011)

Keep a video log if possible, helps for troubleshooting later if need be and post a vid when install is completed. Good luck!


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## rton20s (Feb 14, 2011)

Thanks JT. Have you happened to test a DEH-80PRS yourself to see where it clips? I plan to have everything in with an initial tune by the next get together. I'm sure I'll be soliciting a lot of advice and listening impressions from the more experienced guys down there though. 

Hpilot... I've gone through all of the white papers currently available on HAT's website. While they have a ton of information (which I have probably read 1/2 a dozen times now), they don't really have any information on setting gains or tuning. 

The amp kit will be coming from Knu Konceptz and should be plenty good enough quality for my install. That and the deadening will be ordered as time and money allow. I'll also be running all of my RCAs (6 channels) at the same time. No reason to do otherwise. 

Not sure about a video log, but I have started a build log thread here on DIYMA. I'm hoping to get plenty of photos and detailed information on the install.


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## hpilot2004 (Dec 13, 2011)

With the Arc 900.6 you can, as you know, level set each channel to make your mids and tweeters blend smoothly. I use a RF360.2 processor in my setup and like it. I clipped the inputs to the RF unit slightly and kept my gains down on the amp. I have a very low noise floor to me, but like I said before I do not get to technical as others tend to do. I suppose I should get it done by someone that actually knows how to tune, It would probably sound a lot better.


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## south east customz (Jan 17, 2011)

Use the most usable output from your headunit as the basis. 
If its a good deck, u won't clip at maxed output.
Then u can work ur way into over/under if you need to fine tune


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