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Author Topic: Voltage  (Read 6939 times)

Ron Steigmajer

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Voltage
« on: June 15, 2008, 12:44:23 am »

Hey everyone,

I'm in need of a little help & advice.

I'm trying to get the best method to obtaining the voltage from my amp (Crown XTi2000) & speakers (Yamaha S215V) to match in stereo mode.

I've got this method for my speakers (not to sure if it's correct) voltage = sq root of watts X impendance = 500 watts X 4 ohms = 2000 then hit sq root = 44.721 volts AC. (500/1000/2000 is the rating of the speakers at 4ohms)

I currently don't have limiters set So I'd be getting the full 800 per channel.

I was wondering which type of Wave I should use to get the most accurate reading (i.e. Sine Wave, Pink Noise). I've got a volt meter ready to do testings.

If you need more information, let me know. I've left a attachment, which includes a frequency range and specs of the speakers. I don't know how to read the information by myself.
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Rob Timmerman

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Re: Voltage
« Reply #1 on: June 15, 2008, 01:36:06 am »

If you're using an AC voltmeter, you want to use a sine wave, preferably around 60hz as a test tone.  The speakers need not be hooked up for this test.  There were a few (2-3) threads on setting limiters in the past month or 2, so you might try a search...
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Ron Steigmajer

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Re: Voltage
« Reply #2 on: June 15, 2008, 01:51:08 am »

Hi Rob,

I've tried a Sine Wave at 60Hz before but I got a maximum of 18.8ACV and after that I've been told not to use a Sine Wave. The 18.8ACV was at maximum gain with no limiters set.

Edit: Unless I'm doing something wrong  Confused I run the amp straight to the computer and use winamp as an application.
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Don Boomer

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Re: Voltage
« Reply #3 on: June 15, 2008, 09:42:11 am »

You are measuring the output of the power amp ... correct?

Yes use a sine wave since that's what an RMS voltmeter is meant to read.

It's unlikely that you'll ever drive the amp to get 800 continuous watts out of it using music.  You should be in good shape with the amp at full as long as you don't clip the amp (does the amp have built-in clip limiters) or do something really careless.  Your 800W amp is compared to the 1000W program rating of the speakers.

read this ...

peavey.com/support/technotes/poweramps/HOW_MUCH_POWER.pdf
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Don Boomer
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Ron Steigmajer

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Re: Voltage
« Reply #4 on: June 15, 2008, 10:33:41 am »

Ah k,

I think I've got it worked out. I was using a normal voltmeter instead of a RMS voltmeter (never knew something like this existed) thats why I only got 18.8ACV.

Would someone be able to attach a Sine Wave file which I can just open using winamp to test it.

Can you use a normal volt meter to get the same reading as the RMS voltmeter?
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Todd Rasmussen

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Re: Voltage
« Reply #5 on: June 15, 2008, 10:41:43 am »

Ron,

Have you considered getting some experienced hands-on help getting your gear set up?

Seems you've been struggling with all this for quite a while now.

Just a thought...
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Rob Timmerman

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Re: Voltage
« Reply #6 on: June 15, 2008, 01:21:08 pm »

Ron Steigmajer wrote on Sun, 15 June 2008 10:33

Ah k,

I think I've got it worked out. I was using a normal voltmeter instead of a RMS voltmeter (never knew something like this existed) thats why I only got 18.8ACV.

Would someone be able to attach a Sine Wave file which I can just open using winamp to test it.

Can you use a normal volt meter to get the same reading as the RMS voltmeter?


With a pure sine wave, an inexpensive AC voltmeter and a true-RMS AC voltmeter should give the same reading.  A true-RMS AC voltmeter will give more accurate results with non-sinusoidal waveforms.  I believe Lee Pazitus did some testing a few years back on the magnitude of this difference, and posted the results here.  ISTR that the differences are small.

I'm guessing that your problem is that your computer doesn't have enough output to drive the amplifier into full output, and the maximum of 18.8V is limited by what is input to the amplifier.  Perhaps try adding a mixer in front of the amplifier to increase the level you can drive the amplifier with.
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Don Boomer

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Re: Voltage
« Reply #7 on: June 15, 2008, 01:46:12 pm »

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Don Boomer
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Ron Steigmajer

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Re: Voltage
« Reply #8 on: June 15, 2008, 09:43:22 pm »

Hi todd,

I have considered getting some experienced help, I've been to all the music stores that sell PA gear and all they asked me was "Where did you get the gear from?" and I said "Big Time Audio (in USA)" and then they say "We can't help you because you didn't buy the gear from us etc". There are only a few stores in Perth that sell this gear.

Well I did ask Big Time Audio, they told me to use the -6dB limiter and not to clip the amp. 6db below full output is a rough guess of 200? from a 800 max output amp. Which is kinda useless.

Anyway, I think that Rob could be correct. It could be that my sound card doesn't put out enough input for the amp. I've got to have a look at that.

I appreciate all the help guys. Thank You Don aswell for the website for the test tones.

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Ron Steigmajer

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Re: Voltage
« Reply #9 on: June 18, 2008, 09:45:48 am »

Well guys, I've done some more testing and my XTi2000 starts to reach clipping light at ~23ACV, the clipping light shows clipping at full output (800), so I'm using these calculations

23/800 = 0.02875 * 500 = 14.375ACV (to get 500)

So I've hooked up a volt meter and using a Sine Wave from http://www.binkster.net/extras.shtml I've turned up the dial on the amp to reach a maximum of 14.375ACV (this is when my inputs are all maxed out).

This should keep me safe, I usually run inputs at 75%, so I should be good because that will give me less than 14.375ACV. Until I get some further information I will use these settings.

Please let me know if I've done wrong calculations etc.
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Steve Milner

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Re: Voltage
« Reply #10 on: June 18, 2008, 06:59:44 pm »

Ron Steigmajer wrote on Sun, 15 June 2008 21:43

Hi todd,

I have considered getting some experienced help, I've been to all the music stores that sell PA gear and all they asked me was "Where did you get the gear from?" and I said "Big Time Audio (in USA)" and then they say "We can't help you because you didn't buy the gear from us etc". There are only a few stores in Perth that sell this gear.



Although the guys and gals that work in some music stores can be very helpful and knowledgeable, they are not the right people to approach about continuing your sound education. Of course it is in their best interest to help you in the hopes that you will return when you do have a purchase to make, but when I think of "Experienced Help", I do not think of salespeople!
If you went into a guitar shop and purchased even the most expensive guitar in the store, I doubt that you would go back to that salesman every time you needed to learn a new chord and expect the salesman to help you.
A better resource would be local sound professionals in your area that make a living doing this stuff. There are plenty of helpful guys and gals in this business that are far more eager and qualified to help you out...sometimes working a few gigs for free in exchange for learning can be a great way to gain experience and contacts.
Have Fun
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Silas Pradetto

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Re: Voltage
« Reply #11 on: June 20, 2008, 04:38:30 pm »

Ron Steigmajer wrote on Sun, 15 June 2008 00:44

Hey everyone,

I'm in need of a little help & advice.

I'm trying to get the best method to obtaining the voltage from my amp (Crown XTi2000) & speakers (Yamaha S215V) to match in stereo mode.

I've got this method for my speakers (not to sure if it's correct) voltage = sq root of watts X impendance = 500 watts X 4 ohms = 2000 then hit sq root = 44.721 volts AC. (500/1000/2000 is the rating of the speakers at 4ohms)

I currently don't have limiters set So I'd be getting the full 800 per channel.

I was wondering which type of Wave I should use to get the most accurate reading (i.e. Sine Wave, Pink Noise). I've got a volt meter ready to do testings.

If you need more information, let me know. I've left a attachment, which includes a frequency range and specs of the speakers. I don't know how to read the information by myself.



Wait...if I'm reading this right, you should be setting the limiters just so you avoid clip. 800 WPC is not even enough for a 1000W program speaker...you want double the RMS of a speaker.
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Don Boomer

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Re: Voltage
« Reply #12 on: June 21, 2008, 02:45:56 pm »

Limiters are set to prevent too much power from reaching the speakers ... not to keep an amp from clipping.  What you want is to set your limiters so that you don't deliver more than the average rated power to the speaker .... amp clipping or no.
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Don Boomer
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Silas Pradetto

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Re: Voltage
« Reply #13 on: June 22, 2008, 07:28:41 pm »

Don Boomer wrote on Sat, 21 June 2008 14:45

Limiters are set to prevent too much power from reaching the speakers ... not to keep an amp from clipping.  What you want is to set your limiters so that you don't deliver more than the average rated power to the speaker .... amp clipping or no.


Right, but the amp is not even big enough to properly power the speaker, so all this calculation is moot. Just set the limiter at -3 to prevent clipping and you're done.
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Ron Steigmajer

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Re: Voltage
« Reply #14 on: June 22, 2008, 09:23:21 pm »

Hi,

I'm aware the amp cant put out the full usage of the speakers, it was all I could afford at the time (so it will have to do). It's only around ~3dB difference which isn't that noticable. Pretty much as Silas said, I'll put the limiter on -3dB and it'll be fine aslong as I don't clip the amp.
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Don Boomer

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Re: Voltage
« Reply #15 on: June 23, 2008, 11:11:53 am »

Did I miss something? ...

The OP stated that the amp can put out 800 watts and the speaker is rated for 500 watts ... so you need to set the limiter to limit at 500 watts.  Clipping doesn't bother the speaker at all.  Power on the other hand does.

Don't confuse "properly power" the speaker with "deliver the full thermal rating power" to the speaker ... they are two different things.
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Don Boomer
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Ron Steigmajer

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Re: Voltage
« Reply #16 on: June 23, 2008, 09:50:05 pm »

I'm getting more and more confused. To clear it up, the speakers are rated 500/1000/2000 (noise/program/peak). Some people say to put 500 into the speakers, others say 1000. Well my amp can put a max of 800 out. At what should I draw the line? I have a volt meter and a sine test signal from 20hz-22khz (but have crossovers set so no unwanted feed would go through), my amp are at 0db att. Currently don't have limiters set, will test and set limiters accordingly to the voltage required for the rating you guys will give.
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Don Boomer

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Re: Voltage
« Reply #17 on: June 23, 2008, 11:23:45 pm »

OK ... take a breath.

500W is the continuous power rating.  If you DELIVER more than 500W continuously to the speaker it will fail (according to however Yamaha specifies the test).  The speaker can also handle peak power of 2000W for very short duration (again however they actually spec it).  Speakers are typically tested using a shaped noise with 6 dB peaks ... so at the same time it's delivering 500W continuous it's also delivering 2000W peaks at the rate of maybe 50 - 100 per second.

Program power is a made up term to indicate the largest amp that should normally be used with the speaker.  This rating it 2X the continuous power rating because playing music through an amp will NEVER deliver it's full continuous power.  Typically when the clip/limit light fires the amp is delivering between 1/9th and 1/3rd of it's continuous power (so read that ... your 1000W amp typically delivers between 120-333W when it goes into self limiting/clipping).  You can safely use a 10000W amp just as long as you only DELIVER no more than the continuous rated power (that's advanced user stuff)

Amplifiers do not put out program power ever ... just a max continuous or a max peak.

Realize all of this is only a guideline ... not a guarantee.  It should be good for most RESPONSIBLE users.  Amps do not kill speakers ... people kill speakers.  Also remember that this power rating will give you the most output level but it will be at the expense of speaker distortion and shorter life.  Not a good idea to be maxing out your system as standard operation procedure.

Here's some more reading ...

 http://www.peavey.com/support/technotes/poweramps/HOW_MUCH_P OWER.pdf
 http://www.peavey.com/support/technotes/concepts/THE_LOUDSPE AKER_SPEC_SHEET_GAME_2005.pdf
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Don Boomer
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Ron Steigmajer

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Re: Voltage
« Reply #18 on: June 24, 2008, 01:46:20 am »

haha, thx for that Don,

That's how I had it in my head, the 500 is the continous I should have it set to. But other people telling me differently and tell me that they are putting between 800-1000 into these speakers, thats why I was confused. But, I trust you, so I'll only put 500 to the speakers (as I originally had planned to). And saying that, my amp is between 1.5 to 2.0 times the continous output.

Well, I appreciate the information and clearing it up for me. I'll need to get a new soundcard + balanced cables and I should get a lot better quality sound and higher voltage coming through because at the moment I seem to only get around ~40ACV at the most from my amp after I shortened my RCA leads  Very Happy before I was getting about ~23ACV, so I'm hoping the new soundcard and balanced leads will make a difference in the voltage, if not atleast better sound quality.
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