BillFitzmaurice.info

I'm curious if you guy's just use a multimeter to do this or build a dummy load? This is so you don't burn your speakers up. Sadly, we have never done this and I want to protect the new speakers I am building so I don't fry them. If a dummy load is used, how do you make one or buy one?

Thanks in advance,
Patrick

NCcrashman wrote:I'm curious if you guy's just use a multimeter to do this or build a dummy load?

With modern amps, a dummy load is not required.

--Stan Graves

It's like sticking the the test leads in the a/c socket; no load required.

I'll check Youtube and see if someone shows how to do it. Thanks so much guys.

NCcrashman wrote:I want to check the voltage output between the amp and speakers so I don't burn the voice coil up.

I'm not following you.

The slightly longer answer might clear it up.

Solid state amps don't need a load to test the output voltage like a valve amp.

So you just put your tester across the +/- output of the amp and measure voltage in between. No speakers required. Just be sure you're in correct voltage mode or you could fry your meter.

You will also need a test tone...

Jamie

guitarkeys.com wrote:You will also need a test tone...

Jamie

I asked the question wrong. Sorry for the confussion guy's. I read on another site where someone said output is different at various freq's which is why a "dummyload" was needed. It makes more sense to me a dummyload would only be needed if you didn't. Want to punish your ears. Man, I am SO glad I'm here getting correct information. I swear, people on the internet will write anything to look "right". Case in point, I saw a guy do anything to prove under-powering speakers would blow them and you should NEVER use less than double the rms rating of the speaker. I challanged him using the theory that a speaker is blown 1 of 2 ways: mechanical and thermal (learned that here) and a voice coil could handle X amount of volt's. If you don't exceed that, your voice won't fry. He then argued something silly I won't even bring up.

Thanks for the solid information guys.
Patrick

guitarkeys.com wrote:You will also need a test tone...

Jamie

What sort of test tone?

NCcrashman wrote: I read on another site where someone said output is different at various freq's which is why a "dummyload" was needed.

Watts do indeed vary at different frequencies as the impedance has dips and spikes and is not constant. So if you were testing the capabilities of the amp and putting it under stress to see how it fared, then yes, the dummy load is much preferred as it simplifies things VERY much instead of using a speaker.

However, what you're trying to measure does not require a dummy load in any way. Even if you did connect a speaker, a dummy load, or both, once you paralleled the voltmeter, you'd get the same reading.

I actually do this ALL the time with my gear. 1) I run test tones, music, pink/white noise, square waves and hook up ONLY the volt meter; I set limiters based on clipping lights and output voltage. 2) Once the speakers are running, mid gig, I insert the probes in the banana posts of the amp just to see everything is running smoothly and make sure the voltage is right where I want it.

SeisTres wrote:Watts do indeed vary at different frequencies as the impedance has dips and spikes and is not constant. So if you were testing the capabilities of the amp and putting it under stress to see how it fared, then yes, the dummy load is much preferred as it simplifies things VERY much instead of using a speaker.

+1

You're not checking out your amp for anomalies, so the simulated load isn't required.

P.S.

If you ever have a question about amplifiers that boggles you, or you need ammunition for your next gun fight, fill up your mug and give tech support at one of the big dog manufactures a call. They'll be more than happy to talk your ear off, in person, about the right stuff. Especially the folks over at Crown.

Well put! Thank you so much for explaining that. I really have lot's of "stuff" I want to learn. Anyone can be a "sound tech" but only a rare group can call themselves engineers. The guy argued quite arragantly that underpowering speakers would blow them. He had a link to a complete study..lol.

You guys will make me really good at this and I personally thank each and every one of you. Not only do I appreciate the knowledge, but the help as well.
-Patrick

SeisTres wrote:

NCcrashman wrote: I read on another site where someone said output is different at various freq's which is why a "dummyload" was needed.

Watts do indeed vary at different frequencies as the impedance has dips and spikes and is not constant. So if you were testing the capabilities of the amp and putting it under stress to see how it fared, then yes, the dummy load is much preferred as it simplifies things VERY much instead of using a speaker.

However, what you're trying to measure does not require a dummy load in any way. Even if you did connect a speaker, a dummy load, or both, once you paralleled the voltmeter, you'd get the same reading.

I actually do this ALL the time with my gear. 1) I run test tones, music, pink/white noise, square waves and hook up ONLY the volt meter; I set limiters based on clipping lights and output voltage. 2) Once the speakers are running, mid gig, I insert the probes in the banana posts of the amp just to see everything is running smoothly and make sure the voltage is right where I want it.

Radian wrote:

SeisTres wrote:Watts do indeed vary at different frequencies as the impedance has dips and spikes and is not constant. So if you were testing the capabilities of the amp and putting it under stress to see how it fared, then yes, the dummy load is much preferred as it simplifies things VERY much instead of using a speaker.

+1

You're not checking out your amp for anomalies, so the simulated load isn't required.

P.S.

If you ever have a question about amplifiers that boggles you, or you need ammunition for your next gun fight, fill up your mug and give tech support at one of the big dog manufactures a call. They'll be more than happy to talk your ear off, in person, about the right stuff. Especially the folks over at Crown.

I'll do that! You know what's sad though Radian? You just can't teach or tell someone something when in their mind, they already know everything..lol. knowledge is a dangerous tool, unless you have a internet connection

I wire my multimeter to the wired speaker wire outputs on the amp and it tells me what the voltage is. The max for my sub is 60v, so I keep it well below that by watching the meter when the music changes intensity in low frequency.

Harley wrote:

guitarkeys.com wrote:You will also need a test tone...

Jamie

What sort of test tone?

A sinewave is a beautiful thing. The rms value of any sinewave is peak/sqrt2, independent of the frequency. Unlike a selection of music, with peaks that a meter may not catch, the sinewave gives an accurate measure of voltage out vs voltage in.

Afaik the general rule for subs is to use a frequency inside the passband of the sub and call it good. You don't want your filter attenuating the test tone when setting the limiter.