Accuphase P-600 Monster Stereo Power Amplifier Voltage Conversion

Holy balls, the Accuphase P-600 Stereo Power Amplifier is one B-I-G mother of an amplifier. It actually gets physically tiring moving these beasts around the workshop!

Anyway, I’m not complaining, I LOVE working on equipment like this, even if it is heavy and the work slow. The Accuphase P-600 was, as far as I recall, Accuphase’s best class A/B stereo power amplifier back around the early 80’s. There were class A amps which were probably more expensive, and the ridiculous M-100 monophonic power amps, but as far as stereo class A/B amps go, this was king of their hill.

The P-600 produces 300 watts per channel into 8 ohms, much more into lower impedances. It weighs in at 38.5kg and this one even has the optional and gorgeous persimmon wood side panels. It’s superbly well-built, typical of Accuphase. The P-600 also has some useful features like digital power output meters, stepped attenuators and lots of protection.

This unit came in for a voltage conversion, new mains plug and recommissioning on local voltage. Her owner purchased her from Japan, a location where 100V mains is the norm. Naturally, he wanted her converted to 240V operation, carefully tested etc. before flicking the switch. Very sensible customer.

Note that this conversion and recommissioning isn’t a simple flick of an internal switch. Anytime you work on a complex, rare and expensive amplifiers like this, you go slowly. Even more so when changing primary side transformer taps, because one mistake, one slip-up if you were rushing for example and the thing would ash itself at turn-on. Do you want that responsibility..? I know the owner didn’t!

A Look Inside the Beast!

More details and specs on this monster can be found at the audio-database page for the P-600. I’ve also made a short video looking more closely at the P-600. View it and others, on my YouTube channel.

Let’s face it though, you don’t want to hear me rabbiting on, this is what you’re really here for…

Pretty from the front. People generally either love or hate the Accuphase champagne finish. I’m not a huge fan, but yes, I own some Accuphase. You just deal with it when something performs this well.
With the bottom panel off, you’ll see there’s lots going on. Top right, we have voltage stuff. Middle, we have rectification and filtration. Note the polypropylene film caps snubbing the rectifier diodes, and the big fasteners and buss bars on the filter caps. Below that, there’s a protection relay.
Close-up of the crazy buss bars, high-current fasteners and rectification. Again, note the snubbers, these are a nice touch and undoubtedly add to sound quality of this great amp. It’s the little things that really make a difference, all added together.
Here’s a view from the top. Note the superb layout, lack of wiring, Sanken output devices and large toroidal transformer.
Output
Nice, very nice. MOSFET drivers, high current devices and lots of them, paralleled, but interestingly, I notice a kludge – can anyone see it? The black finned heatsinks in the middle of the board are designed for TO-3 devices, but I can see a couple of TO-220 devices in their place, bolted to what are definitely TO-3 heatsinks! Did they run out the higher powered TO-3 devices? Did they become obsolete mid-production run..? I’m curious.
And yes, it really needs the handles. I had to lug this thing around the Liquid Audio facility, and it was h-e-a-v-y. But look at those stunning persimmon wood side panels – they were 16,000 Yen on their own at the time!
Oh, so pretty, and now able to run on 240V! Let me know if you’d like your unit converted, recommissioned or any other work done carefully on equipment like this.

10 thoughts on “Accuphase P-600 Monster Stereo Power Amplifier Voltage Conversion”

  1. Hey Mike, yes these were absolutely wonderful machines. On the M100’s…I had the privilege of listening to a pair of M100’s driving Gale GS401’s with a LP12, FR12 tonearm and a FR7 cartridge many years ago in a hifi shop in Freo. Geez the hair on my arms stayed up for a week ….I couldnt afford the amps or the gales, but i still have that same LP12 and tonearm to this day…just couldnt leave the store emptied handed after that experience.

    Cheers
    Mal

    1. Hi Mal, agreed, I also had a pair of M-100’s at my place a few years ago on audition. I was comparing them to my Krell KSA-150, they were beautiful, airy sounding amps. The Krell had a little more oomph though. Glad to hear the LP12 is still going strong! Have you made any progress on the phono pre front?

    1. Hi Chad

      Sadly, your comment is incredibly mis-informed and illustrates why so much hi-fi gear is damaged or destroyed by people messing with it at home. I’m guessing you made the comment from a lack of understanding / experience, which why I’ve published and responded to it. Be aware that I run an educational website and comments I deem to be disrespectful or dangerous to other readers will be binned.

      So, this unit was imported from Japan and needed voltage conversion, a new mains plug, operational testing and an expert report. Just removing the covers and carefully inspecting the unit took longer than 5 minutes, more like 15. To clarify, this is a complex, rare and expensive amplifier, and I’m a professional repairer, doing this for a living. My customer is non-technical and wasn’t keen to fiddle with transformer taps on his newly-purchased $5K amplifier and risk blowing it up. He also doesn’t own the 1kW variac, multimeters, other test gear and service manual needed verify this amp is working correctly.

      Customers bring equipment like this to me precisely because they don’t have the knowledge, skills, tools and test & measurement equipment to do the work themselves and they want the best care available. In the end, the work I did took over an hour. My customer now has a perfectly working unit and peace of mind in the knowledge that his amplifier has been professionally inspected and converted.

  2. Although it’s fair to say that a real check-up for such an expensive amp will need some time and resources, but despite all the words you needed to make that clear to the contributing fellow Chad, you did not address his statement that a voltage conversion only takes five minutes with this amp especially when there’s a rather user friendly provision for it. My Rowland 7 amp can also easily be converted on the toroid by just relocating a wire from one terminal to another which will cost 10 minutes in total because there’s two of them.
    If you don’t want any criticism on your work Mike you should give your readers not any opportunity to fill in these entryfields. The amount of words you need to brush off this fellow Chad indicates to me that he’s right about the time for the conversion on this P600.

    Cheers mate

    1. Hi Robert, actually I very clearly addressed the ridiculous 5 minute part of the comment, at length. You clearly didn’t understand my response or completely missed the point. I addressed the comment at length because it demonstrated such a profound misunderstanding of the nature of the work involved at this level. As is common with trolls though, he chose not to respond to my rational, reasoned response. By the way, my comments are completely open and uncensored. I receive polite, respectful comments and questions from around the world and basically zero comments like that from the troll, because because the purpose of this site is to illustrate best-practice in hi-fi electronics repair and people who visit realise that. If you’re open to learning, ask questions, become better informed, that’s a nice way to approach things I think. If you think you know better though, forums might be more your thing, this probably isn’t the place for you 🙂

  3. Let it go Mike, there’s no pleasing these people mate. If they want to blow themselves up or risk munting their kit let them at it.

    Cheers
    Mal

  4. Hi Mike
    I have an Accuphase P-600 driving my JBL Summits. The sound is fantastic, but I want to get our local hifi repair guru to overhaul it so it lasts the rest of my life. Do you know where I can get the service manual and schematic for this amp? I am also looking for one for the P-250.

    Thanks a million from Sedona, Arizona in USA!

    Chris

    1. Hi Chris, love Arizona by the way! I get service data via official Accuphase sources where the products are legitimate Australian delivered ones. I am not at liberty to share service data as that would jeopardize my relationship with Accuphase (and other manufacturers) but I would suggest your technician approach Accuphase USA, if these are USA delivered units. They should be able to assist. If they are not USA delivered, it becomes more of a problem and you’ll need to keep searching online, though many of these manuals are literally unobtainable outside official channels.

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