Different voltages through DMM setting gains?

[Sguirrelfeather]

I was resetting gains after a slight mod the other day and discovered something I thought unusual. As I was adjusting the gain, I slipped and the probes came off the amp. When I put them back on, I just put em on a terminal which was nearest. The voltage was different. I thought maybe I just saw it wrong so I checked it again....if my left channel was set at 12.5 volts, my right channel was at 13.4 volts! That's a significant difference when setting a 75W RMS amp...like 80 to the left and 90 to the right. These are just random numbers, not exactly what I had.

So i checked the other set of outputs. I had the same problem, but to a lessor extent. Is this normal for the left and right to be so far off from each other? How do you compensate? Just set gains for the higher voltage of the two?

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[Papermaker85 5,000+ posts]

I was resetting gains after a slight mod the other day and discovered something I thought unusual. As I was adjusting the gain, I slipped and the probes came off the amp. When I put them back on, I just put em on a terminal which was nearest. The voltage was different. I thought maybe I just saw it wrong so I checked it again....if my left channel was set at 12.5 volts, my right channel was at 13.4 volts! That's a significant difference when setting a 75W RMS amp...like 80 to the left and 90 to the right. These are just random numbers, not exactly what I had. http://www.caraudio.com/forums/newreply.php?do=newreply&p=8826508

So i checked the other set of outputs. I had the same problem, but to a lessor extent. Is this normal for the left and right to be so far off from each other? How do you compensate? Just set gains for the higher voltage of the two?

no thats what happens when you use higher tolerance parts in a multi-channel amp. any real "SQ" amp will be balanced or have independent gains per channel..

 

[Sguirrelfeather]

That makes sense. Well, I'm in the market for a new amp anyway....I need six channels and I have two amps currently for that, so looking for a single amp to replace em. I'll take a look to see what's out there.

 

[dbjunior 10+ year member]

What is your source unit? If you are using a pioneer prs unit and have run the auto tune this could be the reason. The auto tune will eq each side independently to match volume levels at the placement of the mic. This is to compensate for the distance from the passenger side vs the driver side. If this is the case set gains with the voltage of the higher side.

 

[Sguirrelfeather]

Oh, nothing like that. It's just a basic amp from JBL. Nothing fancy like auto tune with a mic yet. One day! lol

 

[mlstrass 5,000+ posts]

Could use Balance on the HU to dial it in exact if need be....