3 phase amps

B

Brandon Wright

Freshman
Sep 19, 2012
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Something I have been wondering about lately. Why aren't there more 3 phase amplifiers out there?It sure seems like this would help solve some of the insufficient current supply issues with the modern burst power amps. I am aware of the PKN offering, but I'm curious as to why Lab Gruppen, Powersoft, etc... haven't exploited this.

Ideally, they would be fed DC, but obviously the infrastructure doesn't allow for this. However, a true 3 phase supply seems like it could get pretty close to the same performance. Most anyone who is using PLM or K series amps most certainly has access to 3 phase power and probably has other equipment that requires it as well (motors), so why not?

Discuss away.
 
Re: 3 phase amps

Brandon Wright said:
Something I have been wondering about lately. Why aren't there more 3 phase amplifiers out there?It sure seems like this would help solve some of the insufficient current supply issues with the modern burst power amps. I am aware of the PKN offering, but I'm curious as to why Lab Gruppen, Powersoft, etc... haven't exploited this.

Ideally, they would be fed DC, but obviously the infrastructure doesn't allow for this. However, a true 3 phase supply seems like it could get pretty close to the same performance. Most anyone who is using PLM or K series amps most certainly has access to 3 phase power and probably has other equipment that requires it as well (motors), so why not?

Discuss away.
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The folks with 3 phase power available don't have any problems with available gear. The folks who have problems with enough power don't usually have 3 phase available. Heck, they often don't have a couple of 20a circuits.



Sent from my iPad HD
 
Re: 3 phase amps

The original "BIG' amp was the Crown MA10K It was 3 phase if I remember.

The problem is that nto all venues have 3 phase. Yes many do-but not all. So if you have a smaller gig and they don't have 3 phase-you have an issue. Now your "good" amps won't work.

Sometimes flexibility is the real key.
 
Re: 3 phase amps

Economy of scale, as Rob pointed out. Only the big boys that always have access to 3PH power would buy amps that required a true 3PH input. They'll sell a lot more SKUs that run off of 120 or even 240 than 3PH 208.

Cyberlogic made a 3PH amp about 20 years ago now (yikes…has it really been that long?), but it was one more in the "Turn it on with a broomstick in one hand and fire extinguisher in the other" category. I haven't seen one in the wild in this century.
 
Re: 3 phase amps

Brandon Wright said:
Something I have been wondering about lately. Why aren't there more 3 phase amplifiers out there?It sure seems like this would help solve some of the insufficient current supply issues with the modern burst power amps. I am aware of the PKN offering, but I'm curious as to why Lab Gruppen, Powersoft, etc... haven't exploited this.

Ideally, they would be fed DC, but obviously the infrastructure doesn't allow for this. However, a true 3 phase supply seems like it could get pretty close to the same performance. Most anyone who is using PLM or K series amps most certainly has access to 3 phase power and probably has other equipment that requires it as well (motors), so why not?

Discuss away.
Click to expand...

There are some fundamental advantages to running motors on 3-phase power, completely aside from the availability of more power. For power amplifiers, while there are some advantages to the power supply design from a 3-phase input (reduced ripple and the associated storage requirements, lower input current), these advantages tend not to outweigh the requirement for 3-phase power (and higher cost) for modern amplifiers. Most modern amplifiers have maximum output power greater than the maximum input power, so are relying on internal energy storage to provide that peak output. A three-phase input only reduces the amount of storage required, but does not eliminate it.
 
Re: 3 phase amps

I have one finally question before this thread dies. This probably would probably best be answered by someone with real amp design experience (cough cough JR :D~:-D~:grin:).

Given the current and voltage potential of a three phase power supply, could someone essentially create a PLM20000q with linear output stages that can deliver its full power ad infinitum?
 
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Re: 3 phase amps

Did somebody rub my magic lamp?

Answer to ? #1 it's too small of a market that has access to 3 phase power to justify more dedicated amp development.

I don't know what a PLM20000q is?

3 phases spaced 120' apart, will overlap and when rectified never drop to 0V, but this overlap is not near max voltage so you will still need the power supply to store energy for major power capability.

For serious power you want to use PFC to maximize power extraction from the mains.

JR

PS: I sure hope I am not enabling you guys to be lazy and not figure out stuff by yourselves.
 
Re: 3 phase amps

John Roberts said:
Did somebody rub my magic lamp?

Answer to ? #1 it's too small of a market that has access to 3 phase power to justify more dedicated amp development.

I don't know what a PLM20000q is?

3 phases spaced 120' apart, will overlap and when rectified never drop to 0V, but this overlap is not near max voltage so you will still need the power supply to store energy for major power capability.

For serious power you want to use PFC to maximize power extraction from the mains.

JR

PS: I sure hope I am not enabling you guys to be lazy and not figure out stuff by yourselves.
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Thanks for your reply JR. Sorry, the lab gruppen plm20000q a 4 channel, 4400 watts at 4 ohms, 194 V max voltage swing modern "burst" amp.

Basically, market aside, I want this PKN Controls with a linear output stage, full power long term ( 4000 watts @ 4 ohms per channel for >5 sec), lake processing, and dante network-ability. Is that too much to ask for? :D~:-D~:grin:
 
Re: 3 phase amps

Brandon Wright said:
I have one finally question before this thread dies. This probably would probably best be answered by someone with real amp design experience (cough cough JR :D~:-D~:grin:).

Given the current and voltage potential of a three phase power supply, could someone essentially create a PLM20000q with linear output stages that can deliver its full power ad infinitum?
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There are a couple of issues here-and the power supply is just one of them.

The other is heat and how to get rid of it. If you are talking about sinewave output capability at full power-then there will be a lot more heat-which means larger heatsinks-as just a "starter" of the issue.

Welcome to the problems of designs "back in the day" when amps could produce full power continuously. Yes they are much more efficient now-but ALSO much higher power-which brings on new problems/issues.
 
Re: 3 phase amps

Brandon Wright said:
Thanks for your reply JR. Sorry, the lab gruppen plm20000q a 4 channel, 4400 watts at 4 ohms, 194 V max voltage swing modern "burst" amp.

Basically, market aside, I want this PKN Controls with a linear output stage, full power long term ( 4000 watts @ 4 ohms per channel for >5 sec), lake processing, and dante network-ability. Is that too much to ask for? :D~:-D~:grin:
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Why in the world would you want a linear output stage in 2014? With a linear output stage at 1/3 power you are making more waste heat than sound.

Even if we made a power amp that put out continuous power 24x7, loudspeakers can not handle max power continuously so what is the point?

Don't over think this... embrace the technology.

JR
 
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Re: 3 phase amps

John Roberts said:
Why in the world would you want a linear output stage in 2014? With a linear output stage at 1/3 power you are making more waste heat than sound.

Even if we made a power amp that put out continuous power 24x7, loudspeakers can not handle max power continuously so what is the point?

Don't over think this... embrace the technology.

JR
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True.

It was said several decades ago by one of the "giants" of audio "What we really need is a 100 watt continuous amp that can deliver 20dB peaks".

While this was meant as a joke-it is really true.

If loudspeakers were rated in sine waves-the ratings would be MUCH lower.

But of course some manufacturers would simply choose a freq at which to test that was at the impedance peak-so it would not be "real watts" but watts as calculated based on the rated impedance vs voltage.

So once again it comes down to what the measurement really means and there are ways to "fudge" it to make it appear as something it is not.
 
Re: 3 phase amps

Ivan Beaver said:
True.

It was said several decades ago by one of the "giants" of audio "What we really need is a 100 watt continuous amp that can deliver 20dB peaks".

While this was meant as a joke-it is really true.

If loudspeakers were rated in sine waves-the ratings would be MUCH lower.

But of course some manufacturers would simply choose a freq at which to test that was at the impedance peak-so it would not be "real watts" but watts as calculated based on the rated impedance vs voltage.

So once again it comes down to what the measurement really means and there are ways to "fudge" it to make it appear as something it is not.
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While this is another old story, when I was at Peavey (late 1980s) I designed an amp for the AMR recording division (the PMA70+) this 2x35W continuous amp, put out 2x the voltage (4x the power) transiently. Since this peak power decayed quickly I only rated it for 100W peak for X mSec. Then I recharged the boost circuit so it would deliver 60W for something like 15 seconds, before falling back to the 35W all day long. This amp played much bigger than it was and was sweet for the bedroom recording monitors. Unfortunately my design did not scale up to higher power points cheaply, so this was my first and last amp using this topology. Note: others have used different variants of boosted rail designs with differing degrees of success. With modern class D amps it is simpler to just make the amp put out huge peak power and allow the PS to limit long term power.

JR
 
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