Setting amp gains?
02-21-2006, 07:51 PM
#1
Setting amp gains? What's the best way to set gains on amps? Asking because I have a Kenwood HU that says it has 4.5v preout. However, setting the gains at 4.5 does not work for me. I actually had to set them (front-stage amp, and sub amp) up to just around 0.8~1.0 to get louder sound from my amps. I don't notice clipping, just want to know if I'm on the right track or I should use a different method for adjusting the amps.
02-21-2006, 09:29 PM
#2
This is a simple way. For the sub amp, disconnect the output speaker wire from the amp. Disconnect the RCA cables from all other amps and set the gains to zero. Set the HU volume to 75% of full scale and return any bass/treble settings to 0db. Get a 50Hz test tone and set the HU to repeat. Now, aquire a digital voltmeter and set it to VAC. Now, set the gain using the following equation: (RMS Power x Final Load Impedance) and square root. For example: (610Wrms x 2ohms) = 1220 and becomes ~34.93VAC following the square root. Now, turn the gain until you achieve the output voltage derived from the formula. Reconnect everything and perform for all other amps. If you use for the mids/highs, use a 1kHz test tone.
02-21-2006, 09:49 PM
#3
How to set your equipment gains properly is no longer a mystery! Here we go.
First, I fully recommend using the Autosound Test CD 104, available from http://www.autosound2000.com/Products/cds/index.htm .
The disc has several tracks that demonstrate trading off inaudible or slightly audible distortion, for more amplifier head room. The CD comes with a guide to walk you through choosing how much gain overlap is right for you. Once you choose how much overlap you want, you use a series of test tones to setup your system.
If you do not have this disc, decent results can still be had using a clean recording. What I mean is something smooth, like jazz, or femal vocals. Most rock and pop music has so much distortion in the music itself, it's hard to tell if your system is distorting or not.
First, turn all the gains on all of your equipment all the way down. Now put in your disc, and turn the head unit up. Keep turning it up until you hear distortion. If you can get it all the way up without any distortion, go for it. If you want alittle more head room for quieter recordings, keep the radio at like 75% to 90% volume.
Now, with your radio up, go to your first device in the signal chain. It may be an EQ, a crossover, or maybe you go straight to the amp. Turn the gain on this device up until you hear distortion. Back it off a tad so that the distortion is not audible.
Go to the next device, probably your amps. Increase the gain until you hear distortion, then back off.
Be careful using test tones to do this, especially on mids and tweets. If you are running alot of power, it's easy to blow speakers with test tones. Although it's easier to hear distortion with test tones, you may want to use regular music if this is your first time doing this.
Good Luck!
First, I fully recommend using the Autosound Test CD 104, available from http://www.autosound2000.com/Products/cds/index.htm .
The disc has several tracks that demonstrate trading off inaudible or slightly audible distortion, for more amplifier head room. The CD comes with a guide to walk you through choosing how much gain overlap is right for you. Once you choose how much overlap you want, you use a series of test tones to setup your system.
If you do not have this disc, decent results can still be had using a clean recording. What I mean is something smooth, like jazz, or femal vocals. Most rock and pop music has so much distortion in the music itself, it's hard to tell if your system is distorting or not.
First, turn all the gains on all of your equipment all the way down. Now put in your disc, and turn the head unit up. Keep turning it up until you hear distortion. If you can get it all the way up without any distortion, go for it. If you want alittle more head room for quieter recordings, keep the radio at like 75% to 90% volume.
Now, with your radio up, go to your first device in the signal chain. It may be an EQ, a crossover, or maybe you go straight to the amp. Turn the gain on this device up until you hear distortion. Back it off a tad so that the distortion is not audible.
Go to the next device, probably your amps. Increase the gain until you hear distortion, then back off.
Be careful using test tones to do this, especially on mids and tweets. If you are running alot of power, it's easy to blow speakers with test tones. Although it's easier to hear distortion with test tones, you may want to use regular music if this is your first time doing this.
Good Luck!
02-22-2006, 11:39 AM
#4
I guess my main goal would be for the front speakers to be louder than the rears powered by the HU. They currently are louder, but I'm not sure if I have too much rear fill or not enough. Once I optimize the fronts, I'd like the output of the subwoofer to be equal or a bit louder than the fronts.
02-22-2006, 04:18 PM
#5
The best thing to do is to ditch the rear fill speakers. I have not used mine for 3 years and the sound is much better without them. You cannot adjust the gain from the HU and the rear speakers will be at a set gain. If you have 2 amps, you will have to set the HU volume to a comfortabe level and adjust the amps from there using either the DVM or Audiable method.
