IPR3000 power

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mentor2
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IPR3000 power

Post by mentor2 » Sun May 15, 2011 12:53 am

Hi All,

I'm needing to run a Peavey IPR3000 on Australian 240v mains. I believe it is a 120v power amp. How many watts should I be looking for when buying a transformer to convert the voltage? It will mainly be used in the 2x440watt@8ohm configuration. It may, in the future, be bridged into 4ohm.

Thanks for your help.

Marty McCann
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Re: IPR3000 power

Post by Marty McCann » Sun May 15, 2011 12:28 pm

How many Watts do you plan on getting out of the IPR-3000?

In other words what impedance will it be run into? If you should user it at 2 Ohms, that meands 1500 Watts per channel. You would need a step down transformer that would handle 3,000 Watts.

It probably would have been cheaper to buy in Australia.

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Re: IPR3000 power

Post by Marty McCann » Sun May 15, 2011 12:31 pm

Marty McCann wrote:How many Watts do you plan on getting out of the IPR-3000?

In other words what impedance will it be run into? If you should use it at 2 Ohms, that means 1500 Watts per channel. You would need a step down transformer that would handle 3,000 Watts.

Transformers of that size are usually rate in VA (Volts times Amps). So to get 3000 Watts thru the transfomer you would need one rated at 3 KVA (230 x13 = 3,000).

It probably would have been cheaper to buy in Australia.

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Re: IPR3000 power

Post by mentor2 » Mon May 16, 2011 6:36 am

Hi,

Thanks for your reply, but I found the answer on a spec sheet elsewhere. Just in case somebody else is looking for this information, it is:

1/3 is 662 watts @ 8 and 1236 watts @ 4
and 1/8 is around 350 and 620

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Re: IPR3000 power

Post by Marty McCann » Mon May 16, 2011 10:27 am

mentor2 wrote:Hi,

Thanks for your reply, but I found the answer on a spec sheet elsewhere. Just in case somebody else is looking for this information, it is:

1/3 is 662 watts @ 8 and 1236 watts @ 4
and 1/8 is around 350 and 620
1/8 power is -18 dB down from the full power rating and 1/3 power is -9.5 dB below maximum rating. These figures are what UL requires, and would be the accurate power draw if you maintained 9.5 to 18 dB if headroom. Which is what would be required in a full range system to not have distortion that should be audible. When however we bi-amp a loudspeaker system, we tend to push them harder. Especially in contemporary musical reproductions where we may be slamming subwoofers. In this case, we can indeed draw the amount of current that would represent 1/2 the rated power.

Just saying.

guillaume
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to Marty

Post by guillaume » Tue May 17, 2011 4:13 pm

Marty McCann wrote:Especially in contemporary musical reproductions where we may be slamming subwoofers. In this case, we can indeed draw the amount of current that would represent 1/2 the rated power.

Just saying.
Ok Marty, thanks for that info, that's exactly what I though, but I have something I need to clear. Even after reading the peavey info "how can a amp put out more the the wall socket can deliver" : HOW is it possible to deliver 4080w contiously with my cs4080hz driving 2 vr218....user guide states : the current draw "2,975 watts @ 4 ohms" I don't understand that number, the power cord only delivers 1800w contiously...how can it draw more then it gets? I guess after a few seconds, the capicitor reverse is empty? When ddt light's on, that means what? I guess "empty reserve, amp will lower output to keep it clear" ? I'm wrong somewhere, help me figure it out.

Thanks. that's been a while I need to make it clear...
Guillaume,
Loudspeakers : 2x QW2F, 2x VR218
Amplifiers : 1x CS1400, 1x CS4080HZ, 2x CS4000
Management : VSX26, Kosmos V2.

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SemperFiSound
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Re: IPR3000 power

Post by SemperFiSound » Tue May 17, 2011 5:07 pm

The key word in here:
guillaume wrote:HOW is it possible to deliver 4080w continuously with my cs4080hz driving 2 vr218
is "continuously." The answer is, it cannot.

Music is a complex mess of sine waves, all mushed up together. Continuous power is measured using a single sine wave that REALLY taxes the amplifier.
guillaume wrote:the power cord only delivers 1800w continuously
True. Assuming a 15 amp circuit.
guillaume wrote:how can it draw more then it gets?
It cannot. However, assuming a 120 volt nominal system, if the amp has access to a 20 amp circuit, there's 2400 watts coming down the pike. A 30 amp circuit could permit 3,600 watts. 2,975 watts would be a 25 amp circuit.

The Music that is pushed through an amplifier is not a continuous push - it is a series of ups & downs and once the incredibly heavy capacitor is exhausted and there are no more reserves, ten yes, the amp will protect itself and the rest of the gear by using whatever clip limiting it has available or even taking a brief "pause." This is the amp screaming for help and the wise sound person will heed this warning.

Hope this helps.
Steve
SemperFi Sound; the website
SemperFi Sound On FaceBook
"The Art of War teaches us to rely, not upon the calculated likelihood of
the enemy's coming or not, but on our own readiness to receive him... no
matter what he does." Sun Tzu

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Re: IPR3000 power

Post by guillaume » Tue May 17, 2011 5:51 pm

Thanks Steve, I'm getting it. I have extra questions :
SemperFiSound wrote:Music is a complex mess of sine waves, all mushed up together. Continuous power is measured using a single sine wave that REALLY taxes the amplifier. The Music that is pushed through an amplifier is not a continuous push - it is a series of ups & downs and once the incredibly heavy capacitor is exhausted and there are no more reserves, ten yes, the amp will protect itself
1. Amp headroom is actually amp reserve with "x" desired output.

2. My limiter is set at +9dbu 20:1 for the vr218s. With the cs4080 ST 4 ohms, DDT steps in before the limiter. Not absolutly sure, since no way to know with the vsx, but I tried once a cs4000 bridge on each vr218 and It's a bit louder, so I guess the limiter wasn't in with the 4080...? I tring to figure out that actually, the limiter is usefull only if I have enough amp headroom available to be able to drive over that limiter, with the cs4080 ST 4ohms, seems like not over the 8dbu level.

3. Like Marty wrote, today's music has tons of bass, I can see it since even with a cs4080, the ddt lights on easily when fed with pop music, bass material in those is insanely taxing, to me it feels even worse then hard rock on the amps. So It would be much better to use a cs4000 bridge on each vr218 when driving that meterial? I'll have an extra 3db amp headroom. Would it be really helpfull to get that extra headroom? Peavey's vr presets guide uses a cs4080 ST 4 ohms?

4. How to calculate the corrections on the VSX when using bridge amplifiers, the limiter is different I would guess? the amp is much more then x40, so the 8dbu is no good anymore. Or do I reduce the line level by 3db? or is it 6db ?

Thanks.

By the way, Peavey should give you extra chips, It's really because of Marty's and Steve's postings that I bough those vr218s with new cs amps. All this 10k investment for not profitable dj'ing!

EDIT : I think it's important to add that all this is for my personal comprehension, it's has nothing to do with the quality of the products. Actually, I'm extremely happy with the cs4080hz/VR218 combo, let me tell everyone who reads this that it is really insanely loud and clear for such compact kit. I was once in a very small inside show (roughly 50'x50', meaby 60-80 teens + band and me)...hard rock material, omg, walls wanted to break appart when drum was kickin', not talking about some dumb ppl 3' in front of the boxes...
Last edited by guillaume on Wed May 18, 2011 3:43 pm, edited 1 time in total.
Guillaume,
Loudspeakers : 2x QW2F, 2x VR218
Amplifiers : 1x CS1400, 1x CS4080HZ, 2x CS4000
Management : VSX26, Kosmos V2.

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SemperFiSound
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Re: IPR3000 power

Post by SemperFiSound » Tue May 17, 2011 6:16 pm

guillaume wrote:All this 10k investment for not profitable dj'ing!
Sure it's profitable! You get to make people happy, watch them dance and carry on, get a bit inebriated and make fools out of themselves trying to get someone to hook up with, etc. That's why I do it. It's better than "people watching" at the airport.
guillaume wrote:My limiter is set at 8dbu 20:1 for the vr218s.
Okay, let's see: X40 amp, 4 ohms per side, and 2040 watts (the lesser of 2040 and 2400 (continuous rating). That limiter should be set at 9.3 dBu.
Using a CS-4000 bridged, you have upped the ante to an X80 amp, 4 ohms and 2400 watts is the target as the VSX Limiter circuit measures continuous, NOT peak. So that would be a setting of 4 dBu. You have also gone from a peak potential of 2040 per cabinet to 4000 per cabinet which is 3 dB. So you get headroom and if necessary, one audible increase in volume.
guillaume wrote:Would it be really helpfull to get that extra headroom?
It depends. Are you constantly seeing the DDT? It is possible that you don't have enough rig for your gig if you are pushing that much and still coming up short. More cones to push more air is a better path to take than push the amps & cones to their limits all the time.
guillaume wrote:How to calculate the corrections on the VSX when using bridge amplifiers, the limiter is different I would guess? the amp is much more then x40, so the 8dbu is no good anymore. Or do I reduce the line level by 3db? or is it 6db ?
Anytime you change amp gain, amp power, resistance and desired output to limit, then yes, the formula has to be recalculated. When you bridge an amp, the Gain factor doubles. I actually downloaded an HP-48 calculator for my Droid phone for free and I programmed the calculator to accept those settings and give me a number. Somewhere in these hallowed pages, I went through the calculation procedure.
guillaume wrote:By the way, Peavey should give you extra chips,
They keep telling me that if I ever get down there, I will be a the "guest-for-a-day." But I thank you for your compliment.

Cheers,
Steve
SemperFi Sound; the website
SemperFi Sound On FaceBook
"The Art of War teaches us to rely, not upon the calculated likelihood of
the enemy's coming or not, but on our own readiness to receive him... no
matter what he does." Sun Tzu

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Re: IPR3000 power

Post by guillaume » Tue May 17, 2011 6:28 pm

SemperFiSound wrote:They keep telling me that if I ever get down there, I will be a the "guest-for-a-day." But I thank you for your compliment.

Cheers,
Steve
haha

Thanks again.
Guillaume
Guillaume,
Loudspeakers : 2x QW2F, 2x VR218
Amplifiers : 1x CS1400, 1x CS4080HZ, 2x CS4000
Management : VSX26, Kosmos V2.

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Re: IPR3000 power

Post by SemperFiSound » Tue May 17, 2011 6:50 pm

Here's the post where I walked through the math for getting a dBu setting for the VSX:
http://forums.peavey.com/viewtopic.php? ... SX#p106887

Hope that helps, and please let me know if you have any questions.
Cheers,
Steve
SemperFi Sound; the website
SemperFi Sound On FaceBook
"The Art of War teaches us to rely, not upon the calculated likelihood of
the enemy's coming or not, but on our own readiness to receive him... no
matter what he does." Sun Tzu

Marty McCann
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Re: IPR3000 power

Post by Marty McCann » Wed May 18, 2011 10:44 am

The post started about the IPR-3000 and segued to the CS-4080HZ.

Guillaume, we appreciate your support.

Once again music is NOT a test bench sinewave.

On the test bench with very stable bench power the CS-4080HZ will actually draw 34 Amperes of current with a sinewave input signal driving a 4 Ohm load per channel. As I said above, the most any amplifier can draw with a musical waveform signal at the input is 1/2 of the rated power. So that would be 17 Amps for a CS-4080HZ, with both channels driven into 4 Ohms with program music. Thus a 20 amp breaker would hold.

At 4 Ohms the maximum voltage available at the output with a sinewave would be 90.33 Volts. (the Sq Rt of 2040 x 4 = 90.33).

However with a musical wave form this would be 63.9 Volts. (90.33 x 0.707 = 63.86)

With your limiter set at +8 dBu, it would be coming on at 1.95 Volts at the input, so 40 x 1.95 = 78 Volts. So yes, you should not be triggering the limiter in the VSX-26 as its threshold is 14 Volts higher than the program music voltage.

Now since the DDT circuit responds to voltage clipping, it is possible for a peak voltage to hit the rail and activate DDT. DDT on triggers at the onset of distortion or clipping. Which means a signal has to clip first to activate. Depending on the frequency, one or a few cycles may clip. The DDT circuit has a moderately fast attack time and a moderately slow release.

DDT does NOT limit the output rating of the amplifier, it simply keeps it from going beyond it's continuous maximum power level. However if the input signal is clipped the amplifier can produce twice the maximum rated power.

90.33 x 1.414 = 127.7
127.7 x 127.7 = 16314
16314 / 4 = 4078.5 Watts

The correct compression threshold for the VSX-26 to RMS limit the voltage to the 2400 Watts continuous level of the VR-218 would be +10 or 2.45 Volts at the input of the amp.
Sq Rt 2400 x 4 = 97.979. 97.979 / 40 = 2.449 = +9.99 dBu.

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Re: IPR3000 power

Post by SemperFiSound » Wed May 18, 2011 12:11 pm

Marty,
I agree completely with your math....
Marty McCann wrote:The correct compression threshold for the VSX-26 to RMS limit the voltage to the 2400 Watts continuous level of the VR-218 would be +10 or 2.45 Volts at the input of the amp.
Sq Rt 2400 x 4 = 97.979. 97.979 / 40 = 2.449 = +9.99 dBu.
However, since the amp is not capable of producing that wattage (2400) should we not set the limiter to keep the CS-4080 within it's parameter output of 2040 watts into 4 ohms?
SQRT(2040 x4) = 90.333. 90.333 / 40 = 2.258 -> +9.3 dBu
I realize that a 0.6 dBu may not be incredibly significant, but in cases where the amp falls "significantly" short of the speakers' continuous rating, I would think this need be taken into account.

Standing by...to learn!
Steve
SemperFi Sound; the website
SemperFi Sound On FaceBook
"The Art of War teaches us to rely, not upon the calculated likelihood of
the enemy's coming or not, but on our own readiness to receive him... no
matter what he does." Sun Tzu

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Re: IPR3000 power

Post by Marty McCann » Wed May 18, 2011 1:40 pm

SemperFiSound wrote:Marty,
I agree completely with your math....
Marty McCann wrote:The correct compression threshold for the VSX-26 to RMS limit the voltage to the 2400 Watts continuous level of the VR-218 would be +10 or 2.45 Volts at the input of the amp.
Sq Rt 2400 x 4 = 97.979. 97.979 / 40 = 2.449 = +9.99 dBu.
However, since the amp is not capable of producing that wattage (2400) should we not set the limiter to keep the CS-4080 within it's parameter output of 2040 watts into 4 ohms?
SQRT(2040 x4) = 90.333. 90.333 / 40 = 2.258 -> +9.3 dBu
I realize that a 0.6 dBu may not be incredibly significant, but in cases where the amp falls "significantly" short of the speakers' continuous rating, I would think this need be taken into account.

Standing by...to learn!
Steve
Well Steve, think about this. Why would you want the amp to undergo a much harder limit, when the internal soft limiter (aka DDT) would provide all of the protection you would need? Now in the event someone would hit the input of the VSX-26 with a clipped mixer signal that would reach or even go above +10 dBu, then yes, the harder 20:1 limiting would still be desired.

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Re: IPR3000 power

Post by SemperFiSound » Wed May 18, 2011 2:52 pm

Marty McCann wrote:Well Steve, think about this.
Processing......whiz, ka-thump...whirrrrr.
I am attempting to keep things under control throughout the entire signal path.
Marty McCann wrote:Why would you want the amp to undergo a much harder limit?
I am just looking at the voltage going to the amp and what I expect out of the amp. I expect at max, 90.33 volts into my 4 ohm load. 90.33 / 40 = 2.258 volts max at the input. Why would I NOT want to limit my VSX output/amp input to that?
Marty McCann wrote:The internal soft limiter (aka DDT) would provide all of the protection you would need.
Okay, I am not about to get into the DDT circuitry limitations and expectations as I am not trained there and the 4080 IS your baby....I know that the DDT kicks in well before max continuous is reached. I thought setting variables to keep the parameters within spec for the entire system would be a good thing. What would be the downside to this? I can't see a loss of headroom. Hmm...whiz, ka-thump...whirrrrr.
Marty McCann wrote:Now in the event someone would hit the input of the VSX-26 with a clipped mixer signal that would reach or even go above +10 dBu, then yes, the harder 20:1 limiting would still be desired.
So it can protect the system in the event of bad gain structure and the sound dude's incompetence.

Anytime the amp or speaker configuration is changed, I always recalculate the limiters to accommodate the least capable part of the system. I take the speaker's continuous rating, the amp's rating for the particular resistance applied and compute the limiter based on the more conservative setting. This can be especially important for me, running QSC amps with varying gains and, while yes, they have "Clip Limit" circuitry, I do not know how it compares in effectiveness to DDT. I'm sure it's the same principal though.

This gives my brain something to gnaw on for today.
Cheers,
Steve
SemperFi Sound; the website
SemperFi Sound On FaceBook
"The Art of War teaches us to rely, not upon the calculated likelihood of
the enemy's coming or not, but on our own readiness to receive him... no
matter what he does." Sun Tzu

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