**Amplifier Gain setting tutorial**

[Erich_121]

FOR THE SUB

There is a very quick way without the math to set your gain. First is set your equalizer the way you want it. Then turn your gain on your amp as low as it can go. Adjust your loudness on your cd player to the loudest you want your speakers powerd by your cd player to go, then slowly increase the gain of your amp untill it just starts to clip, then turn it back a hair. You have just set the gain. Very easy, but not as percise as mentioned above but for most people this is just fine.

The best way to set the gain is to have an osilloscope.

[fej]

Good post. Couple things.

If you use only a DMM you are making several assumptions. One being that the amp you are using is actually making the power that is advertised. IE 100w from a 100x4 amp. If it is making less than advertised you may end up setting your gains too high as the math you are basing your DMM calculation on is incorrect. The other side of the coin is unless your amp came with a birthsheet, and depending upon the quality of the amp you are using, you may actually be making MORE power than advertised, and therefore not using all of your available, unclipped power for your system. IE 127w by 4.

DMM is a very good method, but if you have any knowledge at all with tuning stereo systems, you should do your fine tuning with your ears, unless of course you have an O-scope. Recordings for music are far dirtier than a test tone, and no one spends any time listening to test tones, so IMO they cannot be the end all, be all for final tuning.

I'll probably get flamed being this is my 2nd post, but I am certainly not "new" to audio. Keep up the good work jntar.

Fej

[jntar]

Ive been gone for a while...sorry guys.

Atomic, to test the real power you are getting from your amp you need a clamp meter and a DMM. If you still want to know PM me.

Oden, You will want to wire them like this

Once you wire them like this you will want to bridge the amp to a 4ohm load and use this math.
sqrt(200*4)=28.28v

Erich, I agree the best way is an O-scope. I disagree with setting by ear. You might be able to hear clipping once its to a point that its audible, but clipping isnt always that way. It can be for a very short amount of time and just enough time to burn up a coil or lead...Gain setting with a DMM is the best method for a newer person for the only reason that music is recorded around 10db quieter then a true sine wave. Thus, the amp will never clip.

Fej, You are correct about the power of an amp. But in all reality most amps that are of decent value produce what they rate or more power. I have seen profile amps produce rated power on many occations. Thus even though you may not be getting the full potential...you are still getting exactly what you need.

As far as setting by ear...I wont ever do it for the simple reason that my speakers arent cheap and I sont want to replace them just in case. ;)

[1MeanC3]

Ok, for my sub amp (Kicker ZX750.1) thats powering two kicker 07CVR122's, I got 750x2 = 1500 | Sq.Rt.1500 = 38.72.

I tuned the amp to 38v using a 50hz test tone @ 46 Volume (deck goes to 62). The 50hz tone crackled (static-y)?. If my math is correct, why am I getting a static like sound? The subs are in a SubThump ultra Silverado ex. cab box.

Also, for my components. They are Infinity Reference 6020cs on a Kicker ZX200.2 (100Rmsx2 @ 2Ohms). I got 100x2 = 200 | Sq.Rt.200 = 14.14. Is this number correct?

[1MeanC3]

Also, what would you reccommend for the x-over's? I currently have them both amps set to 80hz.

[SmokedOutZ28]

This is excellent info, i just did this to my brothers tahoe before we started the Ac voltage was @ 5.69 and the gain set @ 4.0 (Alpine digital display) after tweaking it to the proper setup 22.36v it sounds awsome before he complained how he had to turn up the volume high in order to get decent sound with the windows down now he doesnt have the problem anymore it made a huge difference!!! Tomorrow i plan on doing mine i never got around to it after installing my amp but this is something that defently needs to be done.

Quick question
on my brothers setup his required voltage was 22.36 the 1/2 channels voltage were 21.30 and the 3/4 channels were 22.10 both gains set @ 0.4 (Alpine digital display) is that common for them to be different?? I mean it's close enough and he's happy but wasnet sure if it was normal or not if I went any higher on the gain it would go over the voltage required and i didn't want to do that.

[suthrncop66]

Good advice, I have my stuff hooked up but never thought about that kind of stuff...

[socal67chevy]

cool

[jigsawklr]

I hate to chime in here being a noob on here, but I was reading the very first sentence of this thread and I already found a discrepancy. The following line:

clipping is the number one cause of failure

. Like I said, I'm a noob here, and I really don't want to step on any toes, but clipping is not the #1 cause for killing equipment. It's easy for a scrub to pick out the statement and say "but I heard that subwoofers in cars play like 10% distortion anyways, why should I care about bass boost?" I might say something like "clipping may damage equipment" rather than "clipping will kill equipment", or of that nature. Just using a terminology to help make the tips watertight...

This might be a good point in the tips to suggest that power doesn't blow equipment, people blow equipment.

If I were writing this tip line, I might combine the bullets in this general area into something like this:

There are 3 basic ways to kill equipment: mechanical overload, thermal overload, thermal fatigue. Power will not kill equipment, whether too much or too little. You may feed a subwoofer any amount of power you wish. As a general rule, if you can't hear distortion, you will not blow the speaker.

Unfortunately, even this is a misleading and fallacious statement. The bandpass box user will be delighted and crank the volume, hearing no distortion and thinking himself set. No relationship is made between the three methods of speaker destruction and power handling, such a discussion would most likely be too long and drawn out for a general bulleted tip list.

I dunno, I guess if I had to compress it down to a bullet, I would say something like: "power doesnt kill speakers, whether too much or too little, overuse of the gain know plus overuse of the volume knob kills speakers"

And again, its still not enough, it doesn't call for how much gain or volume! Its a tricky one to bullet, I don't think I can come up with anything that'll be good.

But, to say that clipping is the number one cause for killing equipment is just a fallicious statement in and of itself. Clipping is where the wave starts to square off.


Its a rare system that has the ability to tune to ZERO clipping, however. The volume just ends up WAY too low. Only time I ever had zero clipping in my car was feeding 350 rms to each of my midranges, and 150 rms to my tweeters. In the end, it made no sense, and I swapped equipment because of it.

[Atomic]

How about this: "Running too much power to your speakers for too long will cause them to fail"

"too much power" being an amount in excess of what the speaker is designed for, ie 500w on a 300w sub.

[96rollin33's]

i have a 1500.1 kicker amp runnin to cvx kickers. when i turn the bass up when the follow is up it causes the amp to turn off but then it turns back on. what would cause this

[96rollin33's]

when volume is up

[Greenz71obs]

can someone pleasse explain what OMS are?

[audiomecanix]

this is all you need for gain setting.....

[Atomic]

Originally Posted by Greenz71obs

can someone pleasse explain what OMS are?

an ohm is a measure of resistance at a specific voltage and/or frequency

ya want more info google is your friend.search "ohms law"

[zane114]

If I am using two (600w rms) 4-ohm subwoofers wired to 1-ohm into a 1000w rms monoblock amplifier, Am I simply supposed to use the square root of (1*1000) which is 31.62v? Can someone please confirm this, thanks in advance.

[bajakid2]

Hey, iv read the whole thread and i have a kicker zx750.1 and two 10inch mtx 5500s(300 watts each) which are wired for 2 ohms. i came up with the number 34.6 Volts?? does that sound about right??iv never actually tuned my stereo systems with a voltmeter but im going to give it a try to see if i can get better sound out of what iv got already.
correct me if im wrong i read somewhere if you amp overpowers your subs i would multiply the subwoofer watts x2 which is
300x2=600
600x2=1200
then the square root of that was around i believe 34.6??
Thanks for the help-Travis

[Atomic]

yea use the sqrt(1000*1) because thats the max on your amp, so your 31.6v is correct

yea, root of (300*2*2) is 34.6

[chubyboy]

u may have covered it, but i didnt feel like reading 5 pages...now, im a semi pro sound engineer, but i had not really heard of unloading, til i set up my ca system, what might i ask is unloading? mechanival distortion?

also may have been covered, but distortion doesnt kill speakers, a DC clip does...

[chubyboy]

Originally Posted by zane114

If I am using two (600w rms) 4-ohm subwoofers wired to 1-ohm into a 1000w rms monoblock amplifier, Am I simply supposed to use the square root of (1*1000) which is 31.62v? Can someone please confirm this, thanks in advance.

might i ask just how the **** ur getting one ohm from only 2 4 ohm speakers?