Gain Setting

[philwsailz]

IT is the time of the year when we all start thinking abot getting the boats out and ready to go. We certainly have touched on this topic before, but maybe a quick refresher is appropriate?

My personal procedure for setting up system gains in stereo systems:

Turn gains way down but not totally off at the EQ and all amps.

Now turn radio up with your loudest source selection, (radio, MP3, CD etc) until you can audibly hear the sound beginning to distort, get crunchy, etc... Then turn the radio down just barely below that.

Now turn the EQ gains slowly up until you hear that distorted crunchy sound. It should sound similar to the distortion that the radio put out. Turn the EQ gains back down just a little below that.

Finally do the same thing with your full-range-in-boat speakers amplifier. Turn the gains up till crunchy then back off... turn up your sub amp until it blends with the in-boat speakers, and if you cannot get the sub amp loud enough, go bak to the in-boat amp and turn it down to match the sub.

What we are doing here is using our ear to gain-stage the whole system... The method I describe makes every component clip at the same time. Each and every device is more-or-less exactly calibrated where they track uniformly from zero-output to max output.

This will deliver the best signal and will minimize operating noise, clicks, pops, etc...



Props to OriginalWingNut for recommending we touch on this topic here! Thanks OWN!!!

[Original Wing Nut]

Phill thanks to you and Tim, I think alot of us feel more comfortable tackling stereo upgrades and issues with our boats sound systems. I am looking forward to mine in a few weeks. I am so ready for riding season as I busted my arm snowmobiling just after Christmas and have been down for six weeks. I am now doing PT for six more weeks so I can be back to riding when the weather warms.

[Jason B]

What do we do if we can CRANK full volume with no audible distortion? Should I just back it down a couple clicks to be safe? I think my stereo maxes at "30" but I normally notch it back to a max of "28"

[philwsailz]

What do we do if we can CRANK full volume with no audible distortion? Should I just back it down a couple clicks to be safe? I think my stereo maxes at "30" but I normally notch it back to a max of "28"

get your ears checked...

Just kidding... Yes, crank it back a little..

What stereo do you have? I have not known many if any that would go full tilt with zero distortion.

[Jason B]

The CMD4a. I have the gain turned down to less than 1/2 on both amps right now if that makes any difference?? It's still plenty loud so I thought better safe than sorry because my kids think the volume knob is for twisting WFO constantly.

[philwsailz]

hah hah hah... Kids unfortunately are not the only ones who think WFO sounds better...

No, when gain setting, we typically want to have the head unit at only about 3/4 volume because IT usually distorts beyond that level. We are only talking about head unit distortion right now... This distortion has nothing to do with amp gains; it is the output devices in the head unit that run out of steam.

The reason we tweak the head unit to distortion and then turn it down a little is to know roughly where the head unit distortion happens... that way we can set the amp(s) where they go into distortion at about the same time. This makes the total system perform best; you have full range of volume control, and when the sytstem is between songs, or turned down, the hissing, pops, buzzes, etc are minimized...

Understand you need to be careful with your audio program material when setting things up. If you have a quiet song you are using, you might not ever hear distortion due to clipping. Additionally, if you have a song in your library that seems loud, but is recorded quietly, it might never cause clipping distortion either.

I guess that this is a good place to point out that often, ripped digital media files have an unknown pedigree. If you got a tune from a buddy, you do not know what the peak amplitude is, you do not usually know where he got it, what the bit rate was it was encoded in, you do not know other things; these issues can lead you down a poor path of decisions if you are using a dubious copy of a music file to set up your system. For best results, I either use a CD *gasp* or a digital file that I personally ripped from a CD. That way I know that the music density and the peak amplitude are at their highest, giving me the best indicator of where clipping distortion really begis for really loud songs. The other benefit of usign a CD is that it goes right into the head unit. This REMOVES any issue or problems that may exist between your digital media player and the head unit if you are using an outboard digital media player. Many times there are two extremes; First is where the interface between the digital player is quite low; the head unit will never distort due to clipping; it is just not getting enough juice from the media player. In the second instance, the digital media player is delivering a hotter signal than the head unit can handle. This will clip and distort the "front-end" of the head unit. In this instance, the head unit will be distorted at all volume settings...

Some of you will have varying tastes no doubt, and some of you might cringe at this recommendation, but remember it is only for set-up if you do not like the music. Nickleback has some of the best-compressed peak amplitide music files out there. Consider using a few of their tracks to dial in the system; pick the really rocking loud ones.

If I hear of any of you using Celine Dion, Katie bar the door...

[Matt Garcia]

Good post for stereo noobs like myself.

[Jason B]

Thank you Phil!!

[G-MONEY]

On my way to do this now...

Matt you should make this a sticky

[ajholt7]

Awesome thread. Now any advice on setting crossover frequencies?

[AdaminMN]

Your just never satisfied are you AJ.

[ajholt7]

Your just never satisfied are you AJ.

Not unless someone shows up at my house to tune my amp for me. Oh and when they leave there should be a set of Pro80's on the tower. Then I would be satisfied.

[Fuh Sho]

Great write up Phil! i will be doing this when i install the tower, speakers, and amps tomorrow pictures comming soon

[laserfish]

Thanks for this write up Phil. This is the "tuning for dummies" that I was looking for. Thanks Chpthril for putting me on to it. You guys are the greatest for all the help you provide on this forum. Thought it deserved a bump since there are more than a few of us with new stereo stuff this year.