I am going to have two subs that handle a combined 600W RMS with an amp that is going to be giving them 800W RMS. I will most likely have the gain on the amp set at halfway. I have heard and seen this scenario before and was told it should be ok. Supposedly the amp will not be giving out its full RMS power at that gain setting. Is this true? If anyone could shed some light on this, I would greatly appreciate it.

No, it won't. It's really best to have an amp that's capable of putting out a little more power than your subs are listed to handle. That way the amp won't strain itself and heat up as much. The way I'd personally do it, which may be different than the best, is just turn your stereo up to a little higher than your normal highest listening volume, taking off the bass boost or anything like that on your h/u and amp, then turn up the gain on the amp to the point that you can tell the subs are on the verge of distorting and then turn it back a little.

Probably the most accurate way could be found here, though: Sticky

You should be fine. I think half way is a little high. Normally I only set it at a quarter or a little more than a quarter. But how I do it is turn everything down all the way. Then on the head unit put the eq to flat. Turn up the volume to 75%. Then adjust accordingly. You would be surprised on how much you don't need to turn up the amp settings. I do this as a profession. If I had a dime for every customer that brought their amp and subs back because they didn't work, with all the gains turned all the way up, I'd probably have $300.

the amp will be putting out 800W no matter what.

all the gain does is adjust the signal that the amplifier amplifies. the higher the gain, the stronger the signal that is amplified. the opposite for lowering the gain.

there are 2 ways to set your gain, by ear and by meter. both require people with a backround in doing something like this.

and here is a tid bit of info that some of you know: doubling your power only produces +3db. so your 800W RMS amp is only putting out 3 db more than if you would have purchased a 400 w RMS amp. thats alot of money you have to pay for only 3 db.



Injection is nice but id rather be BLOWN!

Set your gains the way Lanman mentioned in his sticky, using a DMM unless you have access to an oscilloscope.
Arbitrarily setting your gains to 1/4 or 1/2 is definitely NOT the correct way to do things, and could very well NOT be fine. Do it the proper way.

Bluecavi - you know as well as I do that telling him that his gains are set a bit too high because you run yours at 1/4 is pointless, because there's a 99.99999% chance that he has completely different equipment from you. Every installer I know sets amp gains using a DMM, because o-scopes aren't always available. Setting sub amp gains by ear is not ideal either, since it's so hard to detect distortion in bass, and it doesn't take alot of clipping to fry voicecoils.
The fact that you just told him that his arbitrary gain setting is fine is quite unnerving coming from a car audio professional.



The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.

Some amps have little voltages around the gain knob. On the low end theres something like 4 or 5V, a little bit before the middle is 2v, and at the end I believe is 0.4v. That is just for a few particular amps (my older Kenwood amp had that)

And if I'm not mistaken, isnt the gain on the amp supposed to be set at the voltages of the RCA's from the source? (headunit usually)

So should I be safe and not use this amp or will it damage the subs?

Using that amp on your subs should be fine. With impedance rise it's very likely that your amp will see impedances much higher than nominal (ie, if you have your subs wired to 1 ohm (nominal load), impedance rise might increase the load your amp 'sees' to 2-4 ohms, so your amp won't be putting out it's 'rated' power). It's because of impedance rise that many people run subs wired to 0.5 ohm on amps that are 1-ohm stable; the actual load may be 1 to 4 ohms (maybe more, maybe less) rather than 0.5 ohms.

Calvin, the method that Lanman included in his sticky is essentially matching your gain to the voltage of the HU. You can clip your input signal just as easily as you can clip you amp's output voltage. When you set your HU to 3/4 or 4/5 volume, this is done because that's usually the level at which your HU makes full undistorted volume (and maximum unclipped preout voltage). What happens if your 4V deck only makes 4V at full volume, but actually starts to clip at 3.6V? By setting your HU to 3/4 or 4/5 volume you're ensuring that your input signal is clean.
So, when you set your gains with a DMM or o-scope (or ear method if that's what you're stuck with), your setting your amp to produce full output (unclipped) at the same point that your HU makes its full undistorted/unclipped output.

I myself have never trusted the voltage marks on any of my amps because I don't know how accurate they are. I'll use my AB VFL150.1 as an example. It has voltage markings on the gain, going from (I think) 0.2 to 4V. That amp was rated by American Bass to put out 150x1 at 4 ohms (in theory 600wrms x 1 at 1 ohm), but it's a cheater amp that benches between 2300-2500wrms at 1 ohm on a 12V system, and alot more at lower impedances and higher voltages. If I set the gain to 2V (which is what my pioneer deck puts out), how can I be sure that I'm getting 2300wrms, and not 600wrms or some nasty clipped signal? I don't, which is why I trust a DMM far more than those markings.



The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.

whitegoose wrote:the amp will be putting out 800W no matter what.

all the gain does is adjust the signal that the amplifier amplifies. the higher the gain, the stronger the signal that is amplified. the opposite for lowering the gain.

.

allthewronginfo.com/try.again

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wysiwyg wrote:

whitegoose wrote:the amp will be putting out 800W no matter what.

all the gain does is adjust the signal that the amplifier amplifies. the higher the gain, the stronger the signal that is amplified. the opposite for lowering the gain.

allthewronginfo.com/try.again

LOL!
I don't know how I missed that idiotic post, but that was an awesome response!




The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.

whats the idiotic part?

the part about the amp always putting out 800W?

all the gain does is adjust signal, which is why it it sounds like it is getting louder when you increase the gain and why alot of people think their gains are volume knobs.

i understand some of my info may not of come out like i ment it to as it sometimes does, but i know what i ment and thats all that matters

and by the way, the website link doesnt work i tried it and nothing happend...lol



Injection is nice but id rather be BLOWN!

I'm sorry if my post was mis understood. I wasn't saying that you should set all amps to 1/4 on the gain. I was just citing that people do get the wrong impression and asume that if you turn everything up all the way you would be fine. I have done installs in which i turn it more than half way but it depends on the equiptment used. I was just saying that I personally don't do it that way. And for the 800watt comment, if that is true then why do they have a max rating. If no matter what you do it will always put 800 then why have any other rating. RMS is just what it will normally be putting out but can change.

whitegoose wrote:whats the idiotic part?

the part about the amp always putting out 800W?

all the gain does is adjust signal, which is why it it sounds like it is getting louder when you increase the gain and why alot of people think their gains are volume knobs.

i understand some of my info may not of come out like i ment it to as it sometimes does, but i know what i ment and thats all that matters

and by the way, the website link doesnt work i tried it and nothing happend...lol

the amp will not always put out 800 watts no matter way..that is WAY wrong, no matter how you word it.

And the gain is used to match the output voltage of your headunit, with the input of your amp.

If the gain is too low, the headunit won't be able to drive the amplifer to make full power. If they are too high, the amp will clip at a very low volume level.

As the volume increases...so does the power output from your amplifier.

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wysiwyg wrote:

whitegoose wrote:whats the idiotic part?

the part about the amp always putting out 800W?

all the gain does is adjust signal, which is why it it sounds like it is getting louder when you increase the gain and why alot of people think their gains are volume knobs.

i understand some of my info may not of come out like i ment it to as it sometimes does, but i know what i ment and thats all that matters

and by the way, the website link doesnt work i tried it and nothing happend...lol

the amp will not always put out 800 watts no matter way..that is WAY wrong, no matter how you word it.

And the gain is used to match the output voltage of your headunit, with the input of your amp.

If the gain is too low, the headunit won't be able to drive the amplifer to make full power. If they are too high, the amp will clip at a very low volume level.

As the volume increases...so does the power output from your amplifier.

Thanks, Wysiwyg

For future reference, if I happen to call a post idiotic it's because that person has given bad advice on a subject when it's brutally obvious that they have absolutely NO clue about what they're talking about.
I'm not here all that often anymore, but I'll continue to call it when I see it. I do it because it's far less expensive for newbs to hear no advice than bad advice.

That being said, I was thinking that I must have been misunderstanding your post, Bluecavi Thanks for clearing it up!



The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.

Well, here's a thought. If an amp is rated at 800w RMS, 800w is the MINIMUM amount of power the amp will produce, no matter where the gain is set. On my MTX amp, I have the gain turned all the way down and it still provides more than enough power for the sub.

ln2johnny wrote:Well, here's a thought. If an amp is rated at 800w RMS, 800w is the MINIMUM amount of power the amp will produce, no matter where the gain is set. On my MTX amp, I have the gain turned all the way down and it still provides more than enough power for the sub.

You may want to check out this website as well:

wysiwyg wrote:
allthewronginfo.com/try.again

because you really couldn't get any more wrong.
By using your theory, when I turn the volume on my HU from 0 to 1, I should go directly from 0 watts to 800 watts, and that value stays the same whether I'm at volume 10 or volume 37.
Did you not read the reply that Wysiwyg made for Whitegoose's post? Here it is again.

wysiwyg wrote:

whitegoose wrote:whats the idiotic part?

the part about the amp always putting out 800W?

all the gain does is adjust signal, which is why it it sounds like it is getting louder when you increase the gain and why alot of people think their gains are volume knobs.

i understand some of my info may not of come out like i ment it to as it sometimes does, but i know what i ment and thats all that matters

and by the way, the website link doesnt work i tried it and nothing happend...lol

the amp will not always put out 800 watts no matter way..that is WAY wrong, no matter how you word it.

And the gain is used to match the output voltage of your headunit, with the input of your amp.

If the gain is too low, the headunit won't be able to drive the amplifer to make full power. If they are too high, the amp will clip at a very low volume level.

As the volume increases...so does the power output from your amplifier.

800wrms is NOT the minimum that the amp will produce, NOR is it the maximum.

Here's what RMS means mathematically.
http://www.answers.com/topic/root-mean-square
Alot of people think of it as an "average" figure, but that's not quite right.

The fact that you have your gain turned all the way down is likely due to using a deck with higher-volt preouts. If not, it's quite likely that you're not getting full power potential from that amp.




The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.

ln2johnny wrote:Well, here's a thought. If an amp is rated at 800w RMS, 800w is the MINIMUM amount of power the amp will produce, no matter where the gain is set. On my MTX amp, I have the gain turned all the way down and it still provides more than enough power for the sub.

omg what is with these people?!?!?!?!?!

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and just when you think you've seen it all on here....





RE Audio

I don't know what to say....
I've never had to break out the bold letters before. Ever. And I was around during the versus days.




The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.

holy smokes thats some bad info
I'm no expert by any means but even i know more than that, and these guys are posting up answers to peoples problems all over this site...makes u wonder how many people have killed their @!#$ due to this...

wysiwyg wrote:i would say they bang, they don't really pound so much. but if
you want to bump, then they will bump and hit real hard and a lot good.

LOL

I'm not saying I'm right, nor was I giving advice, merely stating a thought. Sure, maybe I've read through the MECP books a little, read posts on web sites, that doesn't make me an expert, and I've never said I was. So if you want to call me a retard or an idiot or a ajck ass, go right ahead, whatever helps you sleep at night and feel better about yourselves. I'm not an installer. I have interest in car audio, I like clean sound, I enjoy putting in systems, but I'm no professional. And regardless of what was already posted, and yes I read it, it still makes no sense and here's why. When someone says a speaker is rated at 400 watts, and it needs 400 watts to function properly, you go out and get a 400wRMS amp. Fine. Well if the amp isn't putting out at least 400w at all times then what the fukk is the point of saying it's 400w? If someone tells me that a 400wRMS speaker will not only sound like @!#$ but prpbably be ruined if it doesn't get the power it needs, then I would trust that amp, which is rated at 400w, to do what the manufacturer says it doeos. Make sense? According to everyone that's an expert here, no. So that's why I said what I said.

ln2johnny wrote: When someone says a speaker is rated at 400 watts, and it needs 400 watts to function properly, you go out and get a 400wRMS amp. Fine. Well if the amp isn't putting out at least 400w at all times then what the fukk is the point of saying it's 400w?

A power rating on a speaker is not what it NEEDS in order to properly function, You can give a speaker 5 watts and it won't asplode like you seem to think it would.

Quote:


If someone tells me that a 400wRMS speaker will not only sound like @!#$ but prpbably be ruined if it doesn't get the power it needs, then I would trust that amp,

It's not that amp i wouldn't trust, it's whoever is feeding you that mis-information.

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if doubling your power gives you 3 dbs then what does tripling your power and and taking them to 1 ohm do? running a jl 400wattx1 at 2 ohms right now...subs are wired for 1 ohm....getting a hifonics 1500wattx1 at 1 ohm...

LN2 - the whole purpose of rating a speaker to take XX amount of watts is for warrantee purposes. Companies rate their gear on the side of safely. In the companies' opinion, to get the most reliable/safe performance out of that speaker they don't want you feeding it more than that XX amount of watts. It doesn't mean that you can't give it more power - depending on the sub it may never hurt it (alot of us do it), it's just to cover their arses when you decide to put some serious power to it. Alot of stereo shops feed off of that idea by forcing big amps on newbs that really don't have much of a clue - your 1200w sub doesn't need 1200 unless you want to get every ounce of performance out of it, but I've heard of more than one audio shop that has convinced people into buying more power than they need by scaring them into thinking that "underpowering" a speaker will kill it. They could just as easily tell you how to set the gains properly, and if it's not as loud as you would like, THEN get a bigger amp, but I've never heard of that happening. Total and absolute bullsh!t.

"Underpowering" is probably the most retarded word ever used in car audio. The only time it should EVER be used is when it comes to SPL, but ONLY when people talk about it in the sense that that specific subwoofer could/may still take a bit more power (without melting) to get just a little bit more out of it. If you're into SPL (where huge numbers are more important than anything else), giving a sub 3000wrms when it can "safely" handle 6000wrms is "underpowering" it. If you're seriously competing, you need to get as close to the absolute power limit of whatever you're running to get the very most out of it. If you don't do that, chances are good that you won't be very competitive unless you're an installation god. For regular Joe Blows, this isn't an issue at all. For guys like me, it gets to be an important deal.

What pisses me off the most is shops that pressure you into buying something you don't need through fear (it's to make more money off you, not to help you). I've heard idiots tell someone that they needed to buy a 1200w amp or else they're going to kill their 1200w sub more than once. Just 6 months ago I was in Visions looking at TVs when I heard the car stereo salesman tell a kid that he needed 1/0awg wire for his 600wrms stereo or his car would go up in smoke (the kid already had 4awg wire). WTF???

Wysiwyg hit the nail on the head (as always) - you could feed that same 400wrms speaker just 0.1 watts and it would sound perfectly fine and last forever. At normal listening levels you're probably not even giving your speakers 5 watts. That's where alot of the newbs here make their biggest mistake - they buy a small amp, but things aren't quite loud enough so they krank the gains to try and get their amps to magically make more power than they are capable of putting out, and it kills a sub or two. Clipping has killed 10000 times more subs than people overpowering them.

That's why guys like Lanman, Sweetnloud, Wysiwyg etc keep pounding the idea of correctly setting your gains. We don't do it to sound smart or belittle others - we do it to save people who don't know any better from listening to bad information that can (and will) lead people into killing their expensive stereo gear. If I have to call someone an idiot or use bold letters to keep people from following someone's bad advice, then others will just have to deal with it.

Lastly - go Oilers!!!



The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there's a 90% probability you'll get it wrong.

For anyone that is even thinking about putting any stereo equipment in their car, please for the love of god listen to unholysavage, lanman, sweetnloud, wysiwjg. Me, I am by far no professional installer, but I am not a newb to either. All of my stereo equipment I installed myself. Went and bought my gear. Listened to people tell me that if I do not get a 1200 watt amp for my 1200 watt subs that it would ruin them. I left the shop and went else where. Set your gains accordingly. Another thing that people need to pay attention to when it comes to RMS, the word nominally comes to mind. "Under normal operating conditions", if I am wrong about that please someone give me a clue to that one. Not to mention, the word varible, means that the out put is going to variy. RMS is just a safe operating load so that the manufacturer does not have to replace everything that we decide to blow up. Take JL AUDIO' s sub for instance. The say 750wrms (for an example) but we all know that they can take 1000wrms and be fine, then you could take another JL AUDIO sub and give 1000wrms and it could blow on you. Adjust your gains properly!!!!! If you can set your gains properly take you car to a reputable shop that is not going to be a pusher of anything on to you and have them adjust the settings on your equipment for you. It will save you money in the long run.