Is there a way to find out your preamp/RCA voltage with a multimeter?

[Flyin11]

Ok...I know how to try and set your gains with a multi-meter but I was wondering if there is a way to use it to find out what voltage your RCA's/preamps are putting out? I know I had a discussion a while back about my headunit voltage and how you wouldn't really see 5v unless you had it maxed out in volume. So, I might be looking at another amp and don't want to get into a situation with it if it says 4V max input sens and my HU has 5V. Although I had this setup with a Alpine amp before and had no issues. Just wondering though so I can test and make sure....

[cuibono]

I don't deal with car amps, and I don't know what this has to do with input sensitivity, but if I wanted to know the output levels of something, I would get a recording of a 440Hz sine wave (long enough to be useful, a couple minutes?), and play it. Then with the voltmeter set to AC, just read the terminals. You might not want to have you speakers on, it would probably be loud.

You should be able to find a test tone like the one above on the net somewhere. I'd try and avoid a higher frequency tone because your meter might not be accurate higher up..

Enjoy

[Flyin11]

Thanks but that's not what I was referring to. That's how to set up your gains. I was wondering if there was a way to find out the voltage coming out of your RCA's from your headunit. I saw on another site someone said that you can set your multimeter to read AC voltage and use the positive probe and touch the pointed part of the RCA and then use the negative and touch the outer round part of it and it gives you the voltage coming off the RCA. Someone then replied though and said to be extremely careful cause if you touch one of the parts incorrectly you can burn out the RCA's in the headunit. I would want to be careful so I was wondering if anyone knew anything about this or if there's a way to do it? I'm wondering what mine is sending as I don't have my volume up max at all and never come anywhere near it so I don't really believe the 5V rating Kenwood gives me in the manual as you probably won't hit that unless you are at full power and you still might not get 5V out of it.

[luka]

Hi

MOst units give 2v, so there is good chance your's does too. If you still want to, best way would be with scope, if you will try with DVM usetest tone, 50 or 60Hz tone, + of DVM does to middle or RCA, - to outside, no plastic there, if you put it on plastic you won't read nothing

[Perry Babin]

I'd agree, 50-60hz will probably give the most accurate reading unless you have a true RMS meter.

I'm not sure about other head units but most Pioneer head units will produce the maximum undistorted output at 1 step below the maximum volume (using a 0dBfs tone). For it not to be driven into clipping, you will have to have all EQs and bass/treble settings at 0. The loudness coutour will have to be off.

There is no danger of damaging the RCA outputs unless you allow them to come in contact with a power source (uninsulated 12v wire, speaker outputs of the amplifier...).

This is a 60Hz tone. Burn it to a disc and use it for testing.
http://bcae1.com/temp/60hz60seconds.zip

[Flyin11]

Thanks Will give it a go later on. Tried a 60hz tone before and it didn't sound great to me after I started playing my music again so I've been using a 28hz tone and get a much better bass response. My system seems to like either 25hz or 28hz. Will stick that back in again and see what the RCA's are reading.

[jol50]

Originally posted by Flyin11
and don't want to get into a situation with it if it says 4V max input sens and my HU has 5V.

You should not have to worry about that. Not 100% but I don't know if a HU can even put out its full rating playing music. Ones I have measured on RCA before I got a good dmm were millivolt. But it should not matter as you really should never turn the HU all the way up, and should never have to turn the amp gain all the way up either. Back in the 80s we ran 5v line drivers with no problems. Don't recall there being more than 2v HUs then.

You use a 50-60hz tone because odds are the meter can read standard AC current Hz better, it should have no effect on your system what you test with since RCA will not be hooked up anyway if you are reading voltage of it. Also, any numbers printed on an amp pot for crossover frequency or gain level...don't trust they are accurate. Better to set crossover by ear or with tones than what most amps say, even some crossovers.

[luka]

Hi Flyin11

Its no the point in using 28Hz coz your meter won't show it right, and if it you do it by ear, there is not point of using it anyway, wrong reading is the same as none...If you do it by ear do all by ear...

[Flyin11]

Yeah, I know...The meter fluctuates and doesn't really give you a solid reading but I just judged it by when it stops fluctuating and stays still longer than when it is fluctuating, just for a second or 2, that's where I stop and get it to where I want it. I'm not complaining, I know that it's not totally accurate that way but it sounds great anyways and I like how it is sounding. I can't go 60hz or over anymore...It just doesn't compare and I don't get the sound I'm looking for

[Perry Babin]

Why are you having problems with 60Hz?

It's not supposed to sound good, it's simply the frequency that's most likely to be accurate on a meter that doesn't read true RMS.

The readings should be rock solid and shouldn't vary more than a few thousandths of a volt.