**Amplifier Gain setting tutorial**

[jntar]

Originally Posted by 95Silverado

What about a basslink? Would I set it up the same way? Also, how would I know the voltage of the gain(basslink doesn't have a display for it)?

Very good question. I do not know the answer to this question off hand. Give me a few and I will get back to you.

[jntar]

Here you go...http://manuals.harman.com/INF/CAR/Ow...0LR4-22-05.pdf

page 6

[Nine9]

Good info. Ive seen it all pretty much word for word on some other forums, but good info none the less.

Ive been setting my gains like this for awhile, besides an O-scope, its one of the only ways to safely set your gains.

[Stroker 1500]

Well i went and took my multimeter and put it on the outputs, then i put the test cd in there and turned it 3/4's the way up. When reading it it is giving like 356.9MV's im not quite sure why maybe its a setting in my multimeter somewhere. I'm going to try and screw with it more later though.

[95Silverado]

Originally Posted by jntar

Here you go...http://manuals.harman.com/INF/CAR/Ow...0LR4-22-05.pdf

page 6

Thanks

[jntar]

Originally Posted by Stroker 1500

Well i went and took my multimeter and put it on the outputs, then i put the test cd in there and turned it 3/4's the way up. When reading it it is giving like 356.9MV's im not quite sure why maybe its a setting in my multimeter somewhere. I'm going to try and screw with it more later though.

My guess would be that you had the meter set too low and it was really reading 35.69v

[Stroker 1500]

Originally Posted by jntar

My guess would be that you had the meter set too low and it was really reading 35.69v

ahh yess that was my problem (im retarded). Anyways i did the amp for the subs with the 50hz tone and to my suprise i was pretty close by ear, when i measured the voltage it was 2 volts higher than it should have been according to the calculations so i don't think i did to bad by ear on the subs.

The mids gave me some problems however when i went to set it. I used the 1000hz tone and set the voltage to 20. (100watts rms@4 ohms) which pretty much put the gain all the way turned down. I put in a normal cd and there was pretty much no sound at all, at 35 it sounded like low volume so im not sure if i screwed up somehow or what but it was very quiet at 20 volts to the point where you couldn't hear much of the music. So i put it back to what i had it at originally. i'm thinking that i screwed up somewhere but im not sure where because i did the same thing and it worked perfect for the subs.

Here are the specs on the amp, i'm thinking that i did something wrong in the calculations.. Each speaker is 4 ohms and there are 4 of them connected to the amp
MOSFET 4-Channel Power Amplifier

* Max Power (2 Ohms)
* RMS Power (4 Ohms)
* Bridged Power (4 Ohms)
* Signal-to-Noise Ratio
* Frequency Response
* Dimensions:


* 100W X 4
* 50W X 4
* 200W X 2
* 102dB
* 20Hz-20kHz
* 10-5/8”W x 2-7/16”H x 12-1/2”L

So since the gain controls 2 channels it would be 100 watts rms right? Also would the ohm load still be 4 ohms if you have one 4 ohm speaker hooked to channel one and then another 4 ohm hooked to channel two or does the ohm load change?

[jntar]

Originally Posted by Stroker 1500

ahh yess that was my problem (im retarded). Anyways i did the amp for the subs with the 50hz tone and to my suprise i was pretty close by ear, when i measured the voltage it was 2 volts higher than it should have been according to the calculations so i don't think i did to bad by ear on the subs.

The mids gave me some problems however when i went to set it. I used the 1000hz tone and set the voltage to 20. (100watts rms@4 ohms) which pretty much put the gain all the way turned down. I put in a normal cd and there was pretty much no sound at all, at 35 it sounded like low volume so im not sure if i screwed up somehow or what but it was very quiet at 20 volts to the point where you couldn't hear much of the music. So i put it back to what i had it at originally. i'm thinking that i screwed up somewhere but im not sure where because i did the same thing and it worked perfect for the subs.

Here are the specs on the amp, i'm thinking that i did something wrong in the calculations.. Each speaker is 4 ohms and there are 4 of them connected to the amp
MOSFET 4-Channel Power Amplifier

* Max Power (2 Ohms)
* RMS Power (4 Ohms)
* Bridged Power (4 Ohms)
* Signal-to-Noise Ratio
* Frequency Response
* Dimensions:


* 100W X 4
* 50W X 4
* 200W X 2
* 102dB
* 20Hz-20kHz
* 10-5/8”W x 2-7/16”H x 12-1/2”L

So since the gain controls 2 channels it would be 100 watts rms right? Also would the ohm load still be 4 ohms if you have one 4 ohm speaker hooked to channel one and then another 4 ohm hooked to channel two or does the ohm load change?

Set it up as if it were bridged, I think that it just makes it easier.

Sqrt(200*4)=28.28v
Use the + from channel 1 and the - from channel 2.
Do the same for the other two channels.

If that doesnt make it any better let em know.

[Slammed94]

I have a question, I was doing this today, and by setting my crossover on the amp (by accident) actually affected the reading. Any reason why? So I adjusted that (just realized it btw going out to put it back) and had it to 51.6 (1000 watt amp at 2.67 ohms) but now what do I do with the gain?

How should I set the x over?

[jntar]

Originally Posted by Slammed94

I have a question, I was doing this today, and by setting my crossover on the amp (by accident) actually affected the reading. Any reason why? So I adjusted that (just realized it btw going out to put it back) and had it to 51.6 (1000 watt amp at 2.67 ohms) but now what do I do with the gain?

How should I set the x over?

Set the x-over then set the gain. It can affect your gain. Say you have your sub amp crossed over at 50hz with a 12db slope. You set the gain then change the x-over higher. It can actually make the voltage reading go up, and vise versa with turning the x-over down.


I dont understand your question about "51.6 (1000 watt amp at 2.67 ohms) but now what do I do with the gain?"
Just reset it...

Set the x-over however your ear tells you to. I cant really give you any help on that.
Only advise is generalizations.
subs LP 50-80hz
mids HP 60-100hz
Mids LP 2-3khz
highs HP 2-3khz

[Suareezay]

all this is over my head. Do shops usually do this when intsalling speakers and subs?

[jntar]

Originally Posted by Suareezay

all this is over my head. Do shops usually do this when intsalling speakers and subs?

The few "retail" places that I have been to, No.
Several of the local mom and pop shops that I go to do, funny thing is, I showed them in the first place.

What part is "over your head"? I will try and help you in any way possible.

Honestly, and dont take this as if it directed twords you, I dont really care if people dont believe me when I tell them that it needs to be done. Set your gains by ear, you cant hear clipping, only distortion.

If JL Audio sais to do it you would think that others would believe me.LOL

[Suareezay]

Originally Posted by jntar

What part is "over your head"? I will try and help you in any way possible.

haha, thanks for the offer, but you dont have to help me with anything....im not that big into audio, im just in the process of slowly putting together something decent, nothing for show or competition or anything. I was just curious as to whether or not this was standard procedure at most shops. I wouldnt even try this stuff by myself.

[eaglephan]

Where can I get a test cd at? I just bought a JL audio stealthbox, JL Audio 250/1 Amp and was looking through some sites to get the proper way to set it all up. I just can't find a place to get the test cd.

[eaglephan]

Sorry I just noticed you had the test tones in your first post. This is a great post. When I get my stuff I might ask you for some help. I already have my mids and highs installed with an amp so I'm gonna try all this out with them while I'm waiting for my sub. I think with what I have right now my system should sound better than it does right now. I never thought about any of this stuff I figured they set it all up for you when they installed it. Thanks again for all the good info.

[Gilby]

Could you possibly test the input voltage with all the components hooked up and the incoming leads and get your voltage input that way?

[jntar]

Originally Posted by Gilby

Could you possibly test the input voltage with all the components hooked up and the incoming leads and get your voltage input that way?

Sorry man I havent been around much lately. If by incomming leads you mean RCA input, no, I do not believe that you can set it be them.

If you mean can you set them with your speakers still hooked up then yes you can. But be prepaired, a 1khz test tone isnt too pleasant to the ear.

If I havent answered your question please feel free to email me at jntar@yahoo.com

-Justin

[greydemon]

just got new subs for my truck and this is exactly what i've been looking for, thank you!

[rj.gordon]

I recently put an entire Kenwood system in my 95 Sub. I put in 2 x 1200w sub woofers, and ever since, when I turn the bass up to a decent level, the amps cut out. Is this a grounding issue? power issue? or are my speakers too big for my amps ( 2 x 400w )?

[TITANIUM]

Speakers are too big for the amp or the resistance is too much. The cutting out you hear is called "Clipping".