Voltage meter

[Deutscher]

Hi guys,

I was wondering if there was a voltage terminal that I could put between my amp and speaker cable? (run speaker cable out of amp to the terminal and out to the speaker), Reason I would like something like this is because It would make life so much easier than using a voltmeter everytime. I've seen battery terminals which have voltage display on it.

[StoneX]

What are you using the voltmeter all the time for? Are you measuring the output voltage of the amplifier to the speaker? If so, why?

[kopper69]

Not sure what you are trying to measure. You can measure the supply voltage at the amp, but that is the battery voltage, you might as well measure it at the battery. Output of the amp is going to be the signal that is going to your speaker. That output will be a much higher voltage, very quick depending on what music you have playing and you wont get a meaningful reading.

[Deutscher]

Ok guys, I measure the output voltage from my amps to work out how much to turn the attenuators to get the RMS rating for the speakers. I'm aware that running music through and measuring that will be all over the place, that's why I use a test tone (20hz to 20khz) and I read the peak voltage from that and adjust the attenuators until I get desired voltage. For instance - my DJ speakers are rated for 500RMS which equals ~44ACV, so I hook up voltmeter on the speaker cable and adjust the dials until I reach that rating. Make sense? It just allows me to keep my speakers safe from overpowering them.

[Luke0011]

PLease tell me how you get a voltage rating of 44acv from 500rms please. But yeah what your saying makes sense as in knowing how much voltage your supplying to the speakers not to overpower them. But generally, you should be able to hear if your runing them too hard.

[kopper69]

Well, if you just want to test and setup once, just measure the voltage using a cro across the speaker. Actually you can probably use a multimeter with a true rms reading. You will know the impedance of the speaker, and using the formula Power = (Voltage x voltage) / speaker impedance. Will only be a rough calculation, because the speaker is a coil, which is an inductor and will throw ohms law out a little. Cant really think of another way to measure easily. This will calculate for the test tone only though, music will behave differently. luke0011 is probably spot on in recommending you just use your ears and adjust from there.

[commsirac]

PLease tell me how you get a voltage rating of 44acv from 500rms please. But yeah what your saying makes sense as in knowing how much voltage your supplying to the speakers not to overpower them. But generally, you should be able to hear if your runing them too hard.

Maybe Im wrong, but 44V rms sounds about right to get 500Wrms, which should work on a digital voltmeter.
I am a bit concerned that you would be using test tones between 20- 20kHz to try this though. I dont really think your speakers are rated at those power levels for single test tones!, especially high frequency, where you would fry tweeters at near 1/50 of that level, or even using a 1000Hz tone, which is most likely the frequency your max amp power is rated for.
Perhaps you could do the test with pink noise, which is supposedly more indicative of music.
As has been indicated ^, its just going to be a ball park setting and perhaps it would be best to actually set it up using dummy 4 Ohm loads(not cheap for high power units) rather than your speakers.

In terms of a terminal, why not wire any extra set of wires from each speaker terminal on the amp(with insulated ends)(it will only need thin wire) and just have them sitting where you can access them easily since you are not putting a full time voltmeter in there.

[Deutscher]

Maybe Im wrong, but 44V rms sounds about right to get 500Wrms, which should work on a digital voltmeter.
I am a bit concerned that you would be using test tones between 20- 20kHz to try this though. I dont really think your speakers are rated at those power levels for single test tones!, especially high frequency, where you would fry tweeters at near 1/50 of that level, or even using a 1000Hz tone, which is most likely the frequency your max amp power is rated for.
Perhaps you could do the test with pink noise, which is supposedly more indicative of music.
As has been indicated ^, its just going to be a ball park setting and perhaps it would be best to actually set it up using dummy 4 Ohm loads(not cheap for high power units) rather than your speakers.

In terms of a terminal, why not wire any extra set of wires from each speaker terminal on the amp(with insulated ends)(it will only need thin wire) and just have them sitting where you can access them easily since you are not putting a full time voltmeter in there.

The test tone I am using is Bink's track 6 test tone, it runs from 20hz to 20khz gradually moving up. Reason for this is because I don't know which Hz will be using the maximum voltage. The reason I don't like using ears is because - 1. I've been told that theres distortion before the ear can hear it. and 2. I probably don't have the best hearing lol My amps have crossovers in them which are set to my speakers specs (which I spoke to JBL and Yamaha tech support).

[commsirac]

The test tone I am using is Bink's track 6 test tone, it runs from 20hz to 20khz gradually moving up. Reason for this is because I don't know which Hz will be using the maximum voltage. The reason I don't like using ears is because - 1. I've been told that theres distortion before the ear can hear it. and 2. I probably don't have the best hearing lol My amps have crossovers in them which are set to my speakers specs (which I spoke to JBL and Yamaha tech support).

You'd need to look at the specs for the disc, it possibly has 20-20kHz at 0dB or -10dB or similar. Would anticipate that it is all at the same level, meaning you should measure identical output at all frequencies(at your line level outputs) what your amp does when connected to real reactive loads will change all that. As I said previously, you are most likely going to damage the speakers by trying to drive them at the rated power using a single tone.

[StoneX]

Don't worry about it, everyone tunes by ear, even pro installers. With full range speakers you're going to hear the distortion before anything cooks.

[Tasmaniak]

The only time I personally measure voltage on amp outputs is instances where it's an SPL vehicle and I have multiple amps and multiple subs and they are not strapped. I attempt to bring all the amps within .3V of each other.

[danja]

I've tuned gain based on voltage (and 44v is about right for 500wrms) always worked great for me.

Just measure across the speaker outputs (without the speakers connected).
http://mobile.jlaudio.com/pdfs/gainSetting.pdf