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Epic Accuphase & Krell Power Amplifiers

Welcome back, friends. Here is a sneak peek at some of the larger pieces of gear I’ve been working on including the baddest of them all, the Accuphase P-800, straight outta Japan! Articles on some of these pieces will follow, but at least you get to see them here first.

Finishing these larger amplifier jobs has helped me clear a lot of bench space, which is fantastic. Jobs like these take serious effort and focus but are very rewarding at the same time. Just be mindful that jobs like these take a little longer if you are planning to book something in!

Krell KSA-100/100S

First let’s look at this lovely pair of class A amplifiers, an original 1987 Krell KSA-100 and later 1993 Krell KSA-100S, side by side here and both ready to go back to their happy owners.

Krell KSA-100
Krell KSA-100S
Two legendary amplifiers from one of my favourite manufacturers of the era. On the left, the KSA-100 is a fan-cooled class A beast. On the right, the KSA-100S is a sliding bias class A model, part of the S series. Both are rated at a nominal 100 Watts per channel, but this is a hugely conservative rating. These are class A amplifiers with massive power supplies that make most modern gear look as puny as it is.

There are lots of very good reasons why amplifiers like these are so sought-after. I had an enquirer the other day tell me he thought it wasn’t worth paying for professional refurbishment of amplifiers like this. You’ve gotta be tripping on mushrooms if you think it’s not worth spending a few grand refurbishing amplifiers that cost 30K – 50K to replace. Seriously, buying an amplifier like this and having it refurbished is probably the greatest bang-per-buck decision most people could ever make, and I told him so, more politely of course!

In between these two on the timeline you have the passively-cooled KSA series of which my old KSA-150 power amplifier was a part. You’ll notice a recently serviced Linn Sondek LP12 on top of a gorgeous repaired Marantz 2325 next to the KSA-100S, ready to return to their very happy owners. Yes, I’ve been busy…
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The KSA-100 received a major overhaul and well-deserved full filter capacitor replacement using world’s-best MIL/lab-grade RIFA / KEMET parts, with uprated capacitance because she deserved it!
Krell KSA-150
Here is that other Krell class A amplifier I mentioned, the wonderful Krell KSA-150. Class A, 2 x 150 Watts into 8 Ohms, increasing to about 1.2kW into 1 Ohm. Try finding a modern amplifier that delivers 2 x 1.2kW into 1 Ohm, continuously and that sounds like this! There was also a KSA-250 in this series, a true monster. I love this middle fanless series of amplifiers from Krell.
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The sublime Krell KSA-200S, the bigger brother of the KSA-100S. I repaired and overhauled this beast back in 2020, a massive job it was too. This later S series is fantastic and that 200S story is coming, I promise. Krell even made the truly mammoth KSA-300S! I haven’t worked on one of those yet, not sure I want to!
Krell KSA-100
Krell KSA-100S
I’d like to adequately describe the density of the KSA-100S, but I can’t. Let’s just say I need help moving it. The older 100 seems a little easier to move.
Krell KSA-100
Krell KSA-100S
Incredible amplifiers both and sublime-sounding. In terms of build, the 100S is a lot like Accuphase, better in some ways, not quite as good in others.

Accuphase P-800

Accuphase P-800
And now, direct from Japan for conversion and service…
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Wow, that’s B I G, what could it be..?
Accuphase P-800
Oh, just the biggest, baddest stereo power amplifier Accuphase ever made, the 400 Watt per channel, 47kg class AB behemoth Accuphase P-800 and it doesn’t even have handles! This one is here for assessment, service and voltage conversion and that story will follow. It’s not mine, I wish it was, but it is like the bigger, older brother to my incredible-sounding Accuphase P-360. Because it was shipped directly to Liquid Audio and it’s too large to stay here, I have to get this work done and the amplifier back to its owner ASAP.
Accuphase P-800
She’s dirty but not for long. Most importantly, she is completely original, with not a replacement part in sight. 1988. Some modern amplifiers fail after a year. Progress. New technology. Class D. Yay.
Accuphase P-800
She’s no longer dirty and now runs beautifully. Four simultaneous measurements/adjustments are needed here. This is why I have a drawer full of multimeters, cables, connectors, and probes.
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Thank you very much for your patience if I’ve had your equipment here for a while. This kind of work is wonderful and I thank all who entrust me with equipment like this, but it creates workflow issues I’m sure most will appreciate. Everything you see on this page is massive, and heavy, often requiring two people to even move safely. Equipment like this requires a methodical, technical approach, with zero room for error. The slightest slip with a powerful, irreplaceable amplifier like this and that’s it. Work like this is never an “I’ll just Google it” or “I’ll have a quick look at her for you, sir” type of deal, but it most certainly IS worth doing!

Stay tuned, more big amplifier goodness coming your way.

8 thoughts on “Epic Accuphase & Krell Power Amplifiers”

  1. sjmartined56e3aee1

    What I’d like to know most Mike is which sounds better.

    Have you listened to the Accuphase A-60 which weighs in around 49kgs?

    Steve M.

    1. Hi Steve, yes I have and I’ve also heard the A-30, A-70 and A-75. All are beautiful sounding amplifiers, each with its own strengths and limitations.

      1. sjmartined56e3aee1

        Im glad the A-60 doesn’t feature in that list. I’d be keen to hear what the limitations are Mike say on an A-75. Power consumption and heat?

        1. Hi Steve, sorry, I might be a bit slow today but what list re the A-60? All designs have limitations, even the Accuphase class A models, but they are some of the least compromised designs I’ve seen. Incredibly, your lovely A-60 uses more power and produces more heat than the A-75, and now the new A-80! That’s because yours is more of a beast!

  2. It’s a “Garden of Eden” to read the HiFi stories from Mike. I suggest that Mike
    is actually not in a “liquid state”, but is firmly planted on this earth to give us
    an inspiring look into the world of true music from fine equipment.
    While his writing warms my soul, at the same time I’m ashamed of something.
    As I sit here in France, I look upon my Quad ESL-63s, which are mere decorations.
    My father bought them in 1985 in Hong Kong, along with the other Quad parts.
    After using them in Tokyo, they were sent to California, where we enjoyed them.
    After his death, I sent them to Paris France, where I live now. Around 2008, they
    got that dreaded defective buzz. I put everything in my car, and took the car ferry
    to the factory shop in Huntingdon England, where they replaced speaker panels
    for a much better price than I could find in Paris!! That was then, and now is now!…
    After twelve years, they became defective again. Now they sadly sit quietly in the
    corner of the room. I bought some cheap Klipsch speakers which I use now.
    THE ULTIMATE QUESTION: What should I do with the Quads now? My 75 year old
    hearing is not as good as before, and maybe I’m not ready for the cost of speaker
    repair, not to mention the trouble of trusting an unknown repair shop in Paris.
    So, for now they sit quietly and sadly in the corner of the room, like a dear friend.
    I see no use to cheaply sell them. A dear family friend deserves more than that!

    Jack in France May 8, 2024

    1. Hi Jack, wonderful comment/question and thank you so much for it! I try to stay firmly planted so thanks for noticing. Regarding the ESL-63s: you’ve described what all Quad ESL owners experience and dread. The question, of course, is what to do. Proper repair is essential if you keep them, so finding a good local repairer is important. My colleague here in Perth does it but there must be someone near you who can offer a quality service. The bigger picture consideration is do you want to keep dealing with these repairs? This is one reason the ESL panels don’t work for me. You might consider a smaller, similarly mellifluous conventional design perhaps?

      1. Marius Rajanayagam

        Hello Mike
        Again a wonderful piece.
        For me, the Stax amplifiers were the pinnacle of amplifiers and Accuphase a very close second.
        The Krells are great amplifiers too but they were really just catching up with the likes of Stax and Accuphase.
        Most of all, your articles are always inspiring and remind us of what makes hifi such an amazing pastime. Thankfully, companies like Accuphase have kept the Golden Era alive, before the likes of Linn and Naim took hifi back fifty years where sadly it has mostly remained with British and American kit (except for the well heeled who can spend $10,000 plus).
        I look forward to your next article.

        1. Thanks Marius and, incredibly, I have two Stax class A mono block power amplifiers with me for work now and about to hit the bench. They are not in the same league as Accuphase in terms of build, but they are lovely nonetheless. Thanks so much for visiting and stay tuned for more!

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