Problem with P600

I have an original p600 power plant that I have had since they first came out. It has multiwave I.

Yeah, I know, old school.

I recently acquired a new dac that I plugged in last night. The dac transformer is exhibiting mechanical ringing and buzzing.

This is in sin mode.

I am very familiar with the mechanical sound some equipment makes when run in multiwave modes. This is different.

It starts out as a low ring that gets louder and becomes a buzz and then stops and regular low hum is left. After anywhere from 5-15 seconds later, the cycle begins again with low ring then buzzing. This cycle repeats over and over.

It is almost as if the charge/discharge of p600 caps are passing through.

I have plugged the dac directly into wall with same power cord and get normal transformer low level hum.

The dac seems to sounds fine (i have not yet become familiar with its character), but, from what I have read, transformer ringing is not good.

Any ideas?


The only thing that comes to mind is to try different voltage settings.

Never thought of changing the voltage, but, the unit was running at default 117v.

It kinda surprised me when I heard the ringing, and shut everything down.

I have taken it out of service until I can verify that nothing is wrong with it.

Of possible interest also is that I had a vintage equalizer I had just purchased plugged into PP which blew a channel after 15 mins of being plugged into it. Not saying the PP was the cause, but, it makes you wonder.

Also, I have used the PP for years with tube monoblocks and never noticed any constrained dynamics (I was around 400 watts consumed power on PP.)

I recently got a new tube integrated amp that seems constrained at 220 consumed watts. Again no definite sign of an issue, but, makes you wonder.

Hopefully (or not hopefully :wink: ) someone has experienced something like this and can relay their findings.

Something is definitely wrong here. It is as if the PP is out of sync with itself. I say the EQ problem was a warning shot.

My understanding is mechanical transformer hum can result from DC on the line. Maybe the P600 is putting out some DC for some reason (I used to own a P600 but never experienced anything like this).

Thanks everyone…hopefully Paul can chime in. I opened a ticket with them and will wait for response.

Is there any possibility you have access to a voltmeter? The older Power Plants can, after some time, lose their power supply capacitance and one side of them can get low. If this happens, they won;t output a true 120 volts, it’ll be more like 80 or so. If this happens, it will definitely need to come home for repair.

I started having a similar problem a few months ago. My P600 is probably close to 20 years old. A few months ago my Levinson 360s started making a very noticeable buzzing sound intermittently, say every 30-60 seconds it would buzz for a second or so, enough to make the case rattle. This is the same setup in the same room for over 10 years. I ended up sending the DAC to a Levinson repair shop who could not reproduce the issue, said it could be “environmental”, then proceeded to bill me $1,000 for “upgrades” that appear to have been some new caps and re-soldering a transformer. Needless to say, I just got the unit back and it still buzzes loudly. Problem not fixed:( Following the Levinson repair guy’s suggestion, I plugged the DAC into a separate wall outlet and there was no longer a buzz problem. It turns out the problem is environmental. The configuration I have been using for nearly 20 years without problems had been as follows. Wall outlet->high current Ultimate Outlet->P600->std UO->360s & no.37. I removed the STD UO from the chain and DAC still buzzed if powered by P600. Following the advice in prior thread I checked the voltage: 120 VAC as proper output from one of the P600 outlets. Any other suggestions? Any idea why the only component that appears unhappy to be plugged into my P600 after 20 years is a DAC? Preamp is ok, CD transport ok, turntable, tuner, tube headphone preamp, all ok. Maybe Paul or the OP can shed light based on their experience. I was hoping to be certain that the P600 is the offender before packing it up and going through the hassle of shipping it to CO. Thanks in advance!

Update: reviewed operating manual to see if it would offer any advice. I have always used the Sin setting at 60 Hz output frequency, but wondered if the frequency setting might affect the buzzing of the 360s, so I played around with it. Sure enough, just dialing back the frequency from 60 Hz to 56 Hz eliminated the buzz (“singing” transformer) In fact staying a couple Hz above or below 60 Hz seems to stop the buzz. The only thing I notice is a slight oscillation of the brightness of the red LED display on the 360s. Why after 20 years is the frequency of 60 Hz no longer keeping my DAC happy? Is there a problem with the P600? Is running the P600 at 56 Hz going to damage my gear?

Update 2 : I continued some experimentation and figured out that the DAC transformer buzz only happens in the “Sine” mode. If switched to “tube” or other “P” modes there is no buzz. I do hope there is a fix and that parts might be available.

Nice work tracking down what is causing the issue. I do apologize but parts for the P600 have become incredibly hard to come by. The guys in the lab have essentially put it on the can’t repair list. A few folks have sent theirs in to see if there was anything we could do and they all ended up trading it in for something new. Because you’ve been a PowerPlant owner for so long, we’re able to offer some really great pricing towards a new one.

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Welcome, @mstrammd !

Excellent detective work.

I encourage you to take up James’ offer. As a very long time PowerPlant user I have experienced how much better each new generation of PowerPlants have become and how good the current units are. The upgrade will be well worth it.

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Thanks for your reply, Jamesh. I’m curious as to which unit is comparable to my P600. I was not using it to power my ML No. 23.5, (200W dual mono per side) so not sure that I need one of the larger ones. Would use it for audio sources (maybe would try it with power amp) . Looking for options should I decide to replace. Right now it still works but in slightly reduced way. Was hoping there might be parts that could be scavenged from trade in dead units.

With how efficient the PowerPlants have become, the P12 is actually able to handle a bigger load than the P600. For sources, the P12 won’t even break a sweat. Depending on your amp, you could easily plug it in too. There are a number of benefits jumping up to the P15 or P20 such as passive cooling, lower output impedance, and cleaner output power. However if rack space and budget are limited, the P12 will do a great job as a replacement to the P600.