Big Power Amps with P20

Power Components
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Interested to hear from anyone who has experience running large power amps (either stereo or mono) on their PowerPlant…

It never really occurred to me to even try to plug my Krell FPB-600c into my P20, but the other day I decided to give it a try. I shut everything else down first just to give it extra room, then checked the loading before adding any more components back in. Finally, when convinced that it would carry the load, I fired everything up, and gave it a listen.

My initial impression is that I think I like it better… I’m going to run it this way for a few weeks, then go back to running the amp straight in to it’s old dedicated circuit, and see if it feels like I lost anything.

It is pushing the P20 pretty hard. At moderate volumes, with just the Krell, BHK Pre, and DSD running, the P20 is outputting over 1,000 watts, and as a result, it’s running significantly warmer than I had ever previously observed. It’s interesting to watch the output meter when the bias current changes on the amp…it moves ~500 watts up or down, depending on the sustained level of the input signal. I haven’t yet had an opportunity to drive the amp really hard for any sustained period to see if I can get to the next biasing plaeau, which I’m guessing would draw around 1,500 watts. We’ll see…

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I run my whole system off my P20 and also the Home Theater equipment. I never have two channel shut downs but Home Theater will tax it if the voicing is slanted towards action. Yes the P20 generally runs twice as hot as my power amps ot can be 1200 to 1500 watts and run up over 12 amps continuous.

It sounds better than dedicated lines for the Monoblocks or HT Amp. My amps are MC1000s and a MC7106 that can do combined wattage at lowest THD of about 3KW and 5 KW peaks. There is so much capacitance stored it takes a HT battle seen with repetitive sustained explosions like movie Pearl Harbor to shut down the P20. I have Pearl Harbored my P20 about 4 times watching movies. On Pearl Harbor and opening crash scene of Interstellar. Most movies are not hat bad for sustained room shaking. Having the P20 running surround channels which teo are also full range XXL speakers with LF sub duty is worthwhile.

I can easily run a two channel normal music program at 600 to 1100 WPC peaks without shutting down the P20. I have thought of buying two but the space and extra heat load in the room would be a drag.

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I’m finding that my P20 can’t handle the inrush current on the FPB-600c going from standby to operational unless I shut off all the other outlets. I can bring everything back after I get my 3 blue lights, but if I don’t shut everything else down first, the P20 will shut them down for me…

With respect to heat load, I already had problems just due to the heat from the amp. Now, I have the same heat from the amp, and also the added heat from the P20. Additionally, I don’t really have a ton of air gap around the P20, because without the amp plugged in, it never generated appreciable heat. I’m really liking the sound I’m getting with this setup, but if I stay with it long term I’m going to have to rearrange stuff (not sure how yet…) to get more air around the P20.

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Are you using the 20 amp IEC cable wit a C19? It will give more current. How old is the amp? Do the big filter caps need replacement. Mine used to bleed down and Dim the lights before I got a P20 and had big filter caps replaced. They were leaking.

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I’m interested to hear your opinion after your long term audition on the P20.
I have wondered how an amp with a fully regulated power supply would respond.

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I am using a 20 amp cable, so it’s running at full rated capacity.

The amp was serviced by Krell right before I bought it in 2016, and all the electrolytic caps were replaced, so in theory at least, they should still be fine. Not sure on the exact age of the amp, but it’s roughly 20 years old, +/- a couple years.

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You know…I always thought about it in a similar manner. With the ridiculously overbuilt, and fully regulated power supply on all the big Krell amps, I didn’t think there was much to be gained by powering them with a regenerator. However…

Without delving in to the painful details, My FPB-600c was “in the shop” for about 3 years to resolve an overheating issue being caused by a $0.50 opamp :angry: Fortunately, I still had my older FPB-200, so I ran that during the interim. During that time I finally replaced my old P300 with a P10, and I experimented with powering the “little” Krell with the P10. At the time, I found it inconclusive. Sometimes I thought it was maybe a little better, but most of the time I couldn’t say one way or another.

Because of that experience, when I moved up to a P20 last year (while still running the FPB-200), at first I didn’t bother trying the amp on it, because I assumed I’d get the same result as I had with the P10. When I finally decided to just give it a try, there was no question with the P20…it was clearly better, and remained so over the long term.

When the 600 FINALLY came home, I plugged it straight into the wall (on a dedicated circuit), this time because I questioned whether the P20 could carry a load of that size without interruption. It’s a little bit of a hassle to move cables around, and reconfigure stuff, so I left it alone, and was very happy with the performance I was getting…but it seemed like it wasn’t QUITE as sweet sounding as it was with the 200 powered by the P20. Basically, that’s what finally led me to try the 600 on the P20.

I still want to listen to this configuration for awhile longer so that I can get used to what I’m hearing, then I’ll switch over to non-regenerated and see if I feel like I’m still hearing the same things. Right now, I’m steadily becoming convinced that it’s more natural sounding through the P20, but the whole startup ritual I’m having to go through to keep from tripping the P20 is sort of a pain. :woozy_face:

Long term, I’ll also need to get the P20 more ventilation if I stay with this config, and that might involve some actual work.

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Your house wiring and circuit breaker I am assuming are 20 amp rated.

Sounds like the caps should be good still. The filter caps could bleed down based on power off sequencing. If preamp is playing a source and amp is shut down and pre is still playing. If your amp are like my monoblocks the speakers will play for another 20 seconds bleeding off caps.

Therefore you might ensure music source is off. Then shut of AMP followed by preamp Shutting the pre off first might send a pop to your speakers.

If that doesn’t work I am out of thoughts of what to try.