Monday, December 19, 2011

Hooking up the Power Plant Premier

A few months ago, Music Direct was selling off their B stock of the PS Audio Power Plant Premier at $999, half the original price.  In the new model lineup, you had to get the $3999 model to have the same rated current capacity.  I checked out reviews for awhile, and decided I had to have this for my master bedroom, which is at the end of long circuit that includes my computer room, which no doubt generates a lot of electrical noise.

One of my key thoughts about the Premier is that it would enable me to run my bedroom power amplifier on regulated AC power, which might impart some Krell-like qualities.  My currently non-working Krell FPB 300 has regulated power for the output transistors, a very uncommon feature.  Most power amplifiers have simple capacitor filtered power supplies for the high voltage rails, which could let a lot of the AC line noise interfere.

Unfortunately, when I got everything hooked up and turned on the Premier last Sunday, something was making a horrible buzzing sound.  I disconnected all the things on the switched outlets, and re-hooked one by one.  Only one thing seemed problematical, and that was the Yamaha TX-85 tuner I haven't used in years, but since it sits at the bottom of a bunch of highly interconnected equipment, I simply haven't removed it yet.  So it was easy to leave that unplugged.

But then I plugged in the Parasound HCA-1000A amp I had been using, and it didn't work at all.  Something about the episode with the horrible buzz had somehow broken my power amp.  I'm hoping it's just a blown mains fuse.

Anyway, this was the perfect opportunity to plug in my newer and better amp, the Parasound HCA-1500A, which had been used for awhile in the living room until I got the Aragon.  But as soon as I turned it on, the horrible buzzing came back.  It wasn't connected to anything but AC power from the premier.

Not wanted to break another amplifier, I simply decided to leave the amplifier hooked up to the Monster Power 2000 strip that powers everything not connected to the Premier.  (Both the Monster and the Premier plug straight into the wall.)

So while only intended to make one change, I had to make two: putting line level equipment on regulated AC power, and putting online a better power amplifier.  That helps to make up for the fact I couldn't make the change I wanted to.

It does seem that with these two changes, the sound now has much better depth, a layered depth a bit like the living room system.  The old 1000A amplifier was getting a touch of ripple from deteriorating power supply caps and was making a tiny bit of buzz.  I had previously determined that was not a ground loop problem, it was present even if the 1000A wasn't connected to anything but power and speakers.  The 1500A amp is silent, and that alone makes a big difference.

I can now use the PS Audio remote to turn on and off my system safely.  I haven't been able to use my macro-based X10 system to do that for the past few months because the PC that was handling X10 macros died apparently due to power supply failure.  With the Power Plant Premier, I set a delay on the outlet (actually, the amplifier outlet) that powers the DCX 2496 crossover, so it turns on last.  The DCX itself has a nice muting feature on the outputs, but you can still get a huge pop in the output if you turn the preceding DEQ 2496 equalizer on after the DCX has come on.

Initially I was noticing that both the input and output power were shown as having 2.0% THD.  Then, I just happened to plug in my original style Tensor lamp, and the problem went away (even with the lamp turned off).  Now it shows 2% THD on input and 0.5% on output, which is what one should see with correct operation.

Worried that the problem with power amp might indicate some problem with the output of the Premier, I got out Tek scope and measured through a 1M resistor.  The wave on both AC input and output looked virtually identical.

The heatsinks on top of the Premier do seem to get fairly warm, even with a mere 2.0 amps load.

I still wonder what happened to my 1000A amplifier, and why I couldn't get the Premier to power either of my Parasound amps.  Maybe it's better just power line level anyway.  Although I tend to think of my system as "all digital" there are actually lots of non-digital interfaces:

Denon 2900 analog output goes the #2 DEQ 2496
DEQ 2496 #2 uses analog input
DCX 2496 crossover has analog outputs (driven by barely adequate power supply)

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