Poll Thread: Setting Gains - AVS | Home Theater Discussions And Reviews
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View Poll Results: How's your gain structure:
I don't know what gain structure even is (I'm new). 3 20.00%
I know what gain is, but haven't done anything (it's "good enough" for me). 2 13.33%
I know what gains are and how to set them but I still haven't done it (just smart enough to be dangerous) 2 13.33%
I know what gains are and how to set them, and have and love it. 6 40.00%
I found I had to make it louder after setting the gains (i.e. I don't really know what the hell I'm doing!) 0 0%
I found I had to decrease the level after setting the gains (it was too loud for my tastes) 0 0%
I found I had to readjust the structure to a higher setpoint (1st attempt I didn't aim high enough for my tastes) 1 6.67%
My subwoofer sounds unoptimal, I keep it that way because I like punishing myself. 0 0%
Stuck in analysis paralysis, forever tuning. 1 6.67%
Pure Ignorance is Pure Bliss!!! 0 0%
Voters: 15. You may not vote on this poll

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post #1 of 11 Old 08-16-2014, 01:43 PM - Thread Starter
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Poll Thread: Setting Gains

Curious to see how people are running their gains.
Somehow I have a feeling that many people are running unoptimised, unknowingly.
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post #2 of 11 Old 08-16-2014, 01:53 PM
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I am not new but I don't know what gain structure is. I set the amp to 1/2 then let audyssey run. Adjust the sub level in the avr after that. I though gain leveling was only necessary for pro equipment.
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post #3 of 11 Old 08-16-2014, 02:33 PM
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Here's an interesting article I refer people to now and then: http://www.diyaudio.com/forums/diyau...structure.html A bit different then what the ht crowd is looking for but a good primer on what gain structure is.

It seems to me the ht crowd is optimizing to get the most spl out of the system wrt amp and dac clipping. I prefer to optimize for the loudest I listen at + accounting for headroom. Personally I use low gain/gain adjustable amps (not a voltage attenuator, though I use those too) to allow me to drive my dac at near full output, accounting for headroom, at about 85dB. In effect my system is throttled back, and if I wanted to crank it insanely loud I'd actually clip my dac output. I'm weird I know . I just have it "eyeballed" at this point but in time I'll get out my meter and get serious.
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post #4 of 11 Old 08-16-2014, 02:58 PM - Thread Starter
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Quote:
Originally Posted by Samps View Post
I am not new but I don't know what gain structure is. I set the amp to 1/2 then let audyssey run. Adjust the sub level in the avr after that. I though gain leveling was only necessary for pro equipment.
It applies to home gear too, the problem is home gear doesn't have an input or output indicator usually (heck even most pro stuff doesn't!!!), so you'd need to have an o-scope or you'd be running blind. It doesn't help that home gear often doesn't have the abilities to adjust much of anything.

This isn't the fault of the user as they aren't supplied the necessary tools or knowledge, but it does add fuel to an existing big forest fire when trying to seek perfection or even just non-disastrous results.

Setting gains avoids unnecessary clipping and obtains maximum watts output and minimizes noise & distortion.
If that appeals to you, then setting the gains or levels is best.

You have to factor in the limits of the electronics (unclipped output and thermals), the amount of boost applied in EQ (to avoid additional clipping of inputs or outputs), the user listening preference (how loud they like it), the limits of the speakers, and lastly the master volume of the source material (how loud is was recorded and dynamic range / headroom).
Thus there are a lot of variables, and thus it is: easier said than done.

To add more fuel to the fire, human hearing isn't flat and neither are speakers or room issues.
It changes based on frequency sensitvity and SPL range, and temporary threshold hearing protection shifts or damage at high SPL.
This makes bass sound weak at low SPL and treble sound too loud at high SPL. The good news is that can mostly be solved with DEQ (perfered) or PEQ.

Last edited by BassThatHz; 08-16-2014 at 03:05 PM.
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post #5 of 11 Old 08-18-2014, 09:36 AM
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Quote:
Originally Posted by Samps View Post
I am not new but I don't know what gain structure is. I set the amp to 1/2 then let audyssey run. Adjust the sub level in the avr after that. I though gain leveling was only necessary for pro equipment.
I plan to set my subs up using audyssey as well. I'll set my amp gains to full, and adjust trim in my AVR to meet reference. After audyssey does it's thing I'll boost the trim by 3-6 db. Then I'll run a 0dbfs sine wave using REW to check for clipping.

If you just go for max spl, then reference will be off.....right?

Is there anything wrong with doing it this way?

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post #6 of 11 Old 08-18-2014, 12:02 PM
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My gains are 3 ticks from none on my clones. with max being 30 lol. I don't even get to 3/4 voltage on any content I can stand in room.

Blasting brown notes for 10 years and counting!

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post #7 of 11 Old 08-18-2014, 12:38 PM
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My room is crappy being an unfinished basement for now...I let Audessey run then tweak it till it sounds ok. The one thing that bugs me is...getting it set so music sounds good then when i play a movie I get clipping on the subs.So I sets amps one way for music then back them off to another setting for movies....Its prol all about the acoustics of the room thats the problem i would guess.
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post #8 of 11 Old 08-18-2014, 01:26 PM - Thread Starter
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Quote:
Originally Posted by SeekingNirvana View Post
I plan to set my subs up using audyssey as well. I'll set my amp gains to full, and adjust trim in my AVR to meet reference. After audyssey does it's thing I'll boost the trim by 3-6 db. Then I'll run a 0dbfs sine wave using REW to check for clipping.

If you just go for max spl, then reference will be off.....right?

Is there anything wrong with doing it this way?

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As long as you aren't clipping the inputs or outputs there is no wrong answer, but generally there is no one-solution-fits-all correct procedure that can be followed.

Safety margins, gear beefyness, and personal SPL preferences are all key factors.

Somebody may only like 75db and that's all their gear can handle; while another person has 15 amps all-large with a big sub array and still finds it too "weak sauce".
Some may like their bass 20db hot, other may want it -20db at night.

If you never play over reference and like reaching MAX SPL/Wattage at that setting then go for it. There is no true correct answer. You'll likely exceed THX Reference, but that's ok if you like it and your system can handle it.

But yes, if you aimed for +20db over reference as the clipping point, then reference will sound like it has no bass (most likely); but you WOULD have a large safety margin.

As long as you aren't clipping the inputs or outputs, then there is no wrong solution. If you are happy and it works for you, then it's probably "good enough".
Aiming for perfection is great, but how often is that extra mile needed or called upon... (if ever).
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post #9 of 11 Old 08-18-2014, 01:39 PM - Thread Starter
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Quote:
Originally Posted by doc5150 View Post
My room is crappy being an unfinished basement for now...I let Audessey run then tweak it till it sounds ok. The one thing that bugs me is...getting it set so music sounds good then when i play a movie I get clipping on the subs.So I sets amps one way for music then back them off to another setting for movies....Its prol all about the acoustics of the room thats the problem i would guess.
It has nothing to do with your room.

I have to have my Oppo 105 at 100% with music and my XSP-1 at +3db and foobar at between -32db (low SPL) to MAX (MAX SPL) to reach the SPL I like with music.
For movies I run the Oppo 105 at about 75% (give or take, depending on source mastering level), the rest of the channels (center, rears, LFE) are all adjusted to give the best combination of low-hiss, high SQ, reasonable dynamic range and decent average-SPL.

I run DCX's so I can see if I'm clipping the inputs or outputs.

I've o-scoped the Oppo/XSP combo and it doesn't clip EVER, even outputting 9volts RMS feed by a 0dbFS sinewave. There is enough gain and headroom there that it is NEVER the limiting factor. So it's just a matter of monitoring the DCX's and amp LED's.

With an AVR you just DON'T KNOW what is going on internally; it might be clipping a lot, only briefly, or not at all, you just don't know...
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Last edited by BassThatHz; 08-18-2014 at 01:49 PM.
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post #10 of 11 Old 08-18-2014, 01:46 PM - Thread Starter
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Generally you don't want the amp to be at full gain, unless you absolutely need to because you are doing an RCA to XLR low voltage compensation.
With XLR end-to-end having the gain set to MAX is ludicrous, as it is already in the goldilocks range (no boosting needed); if you did that your house would burn down after your speakers popped.
(Just be careful of that if you ever upgrade in the future.)
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post #11 of 11 Old 08-18-2014, 09:28 PM
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Oh I understand...none of the amps run past 2 oclock on the gains.....I have been an amature sound guy for a band for years so i have dealt with gain structure on the live rig but i cant get my music to sound the way i like with the avr. I may try that foobar program you mentioned. Movies are played on a ps3 untill i can get a oppo or sony player, priority right now is saving for nice DIY LCR. I will work on trying to set the levels of the inputs like you said and find a happy medium. This place is awesome...you learn sooo much Thanks
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