Troubleshooting DMM not reading voltage

[sjv13]

So I was going to set my sub amp gain with my DMM from radio shack. I unplugged the RCAs from the 4 channel, and disconnected the speaker wire from the sub amp. I turned the deck to 50/62, and tuned off all EQ, loudness, etc. Then I played my 50Hz sine wave. I set the DMM to read volts. Then I put the leads in the place where the speaker wire for the sub is supposed to come out of the amp. I got little/no reading (0.001 volts). I adjusted the gain up and down and it never changed. I put the speaker wire back in, and played the sine wave again at a low volume and the sub played it just fine. So I'm not sure why I dont get a reading on the DMM. Am I doing something wrong? I know I am looking for 31.62 volts. Any help is appreciated!

[mylows10]

not supposed to pull the rca's too ,just the speaker wires

[LBC]

DMM should be on Volts AC. NOT volts DC.

[sjv13]

DMM should be on Volts AC. NOT volts DC.

Oh! I didnt check that. I'll see if that's what it is.

not supposed to pull the rca's too ,just the speaker wires

I pulled them from the 4 channel, but left them in on the sub amp which I am setting.

[mylows10]

ok my bad

[sjv13]

DMM should be on Volts AC. NOT volts DC.

I just went and looked at the DMM. It was on DC still, so I'll bet that's the problem. I'll try it again tomorrow. Should work this time.

[dunerider650]

I found with my mac tools unit that it needed a good hard connection i actually had to put the leads of the testers in the speaker wire clamps on the amp and tighten them down to get the correct reading.

[sjv13]

@mylows10 ; @LBC ; @dunerider650 ;

Alright, so I went out to try to set the gain again. I put it on AC this time and I got some type of a reading. There were a few strange things though that make me think I'm still doing something wrong.

1) I need to have the meter set on mV to get a reading anywhere close to the 31.62 I'm looking for, although the number DOES rise with upping the gain and I also tested it with a song to make sure it happens when the bass hits, which it does. I get a reading that looks like this, " ~ 031.6 mV "
2) I played a song with the gain set like this (and the gain was at about 1/5 of the way up) and it was no where near what I was used to hearing
3) It was originally set by a car audio shop, so I set it to where it was before I started fiddling with it and the meter was reading UP TO " ~ 080.0 mV " or so on bass hits in some songs like Smile Back from Mac Miller

These things lead me to believe I'm still doing something wrong. Can you help me?

---------- Post added at 05:16 PM ---------- Previous post was at 05:15 PM ----------

I found with my mac tools unit that it needed a good hard connection i actually had to put the leads of the testers in the speaker wire clamps on the amp and tighten them down to get the correct reading.

I did clamp them down with the set screws actually. And I'm still getting the type of reading in the post right above this one.

[LBC]

@mylows10 ; @LBC ; @dunerider650 ;

Alright, so I went out to try to set the gain again. I put it on AC this time and I got some type of a reading. There were a few strange things though that make me think I'm still doing something wrong.

1) I need to have the meter set on mV to get a reading anywhere close to the 31.62 I'm looking for, although the number DOES rise with upping the gain and I also tested it with a song to make sure it happens when the bass hits, which it does. I get a reading that looks like this, " ~ 031.6 mV "
2) I played a song with the gain set like this (and the gain was at about 1/5 of the way up) and it was no where near what I was used to hearing
3) It was originally set by a car audio shop, so I set it to where it was before I started fiddling with it and the meter was reading UP TO " ~ 080.0 mV " or so on bass hits in some songs like Smile Back from Mac Miller

These things lead me to believe I'm still doing something wrong. Can you help me?

---------- Post added at 05:16 PM ---------- Previous post was at 05:15 PM ----------



I did clamp them down with the set screws actually. And I'm still getting the type of reading in the post right above this one.

On your amp, turn your low pass filter all the way up, turn your subsonic all the way down, turn bass boost off. Make sure your tone is recorded at 0db. Try it again.

[sjv13]

On your amp, turn your low pass filter all the way up, turn your subsonic all the way down, turn bass boost off. Make sure your tone is recorded at 0db. Try it again.

The thing is, even on songs that I know are hitting hard for what my sub can take only get to about 80 mV. That's no where even close to 31.6 V

[LBC]

The thing is, even on songs that I know are hitting hard for what my sub can take only get to about 80 mV. That's no where even close to 31.6 V

That's music. You're wasting your time measuring the voltage on music.

[mylows10]

you need a test tone for setting gains

[sjv13]

That's music. You're wasting your time measuring the voltage on music.

you need a test tone for setting gains

I did use a test tone first. 50Hz sine wave. It was reading under 1 volt no matter how far up the gain was. Like I said, at 1/5th gain (using the sine wave) the meter read 31.6 mV

---------- Post added at 05:43 PM ---------- Previous post was at 05:42 PM ----------

maybe it was a bad file somehow. Can someone link me to a good download? I'll be using it off my iPod.

[LBC]

on your amp, turn your low pass filter all the way up, turn your subsonic all the way down, turn bass boost off. Make sure your tone is recorded at 0db. Try it again.

this

[sjv13]

this

I will try it with those settings. Can you link me to a file that you know is recorded at 0dB? I'm not positive mine was.