Accuphase C-202 Class A Preamplifier Service

As a bit of a teaser for the new year, I hope you like this piece on servicing my Accuphase C-202 preamplifier. The C-202 is a line-level, Class-A preamplifier, with dedicated CD buffer and is fully hardware balanced. It is a superb piece of gear.

I pulled the main circuit board to address some dry joints and clean tobacco residue, left from the previous owner. At the same time, I adjusted all eight DC offset adjustments for each of the two balanced amplifier stages per channel and replaced a blown fuse.

Here we have the overall layout of the beast. Note the large number of high-value electrolytic capacitors. More on this later.

You really cannot beat a circuit with JFETs at every stage, completely symmetrical layout, fully hardware-balanced from input to output, all Class-A gain stages throughout and no ICs or capacitors in the signal path, anywhere. There are lots of other capacitors though and these are placed exactly where they are needed, lowering the source impedance of each local power supply.

In this image you really can see the completely symmetrical arrangement of the + / – elements of each channel. It costs a lot to build something this way, there are no shortcuts here.
Note the beautifully symmetrical arrangement of components, with the same signal paths, same trace lengths etc.
Main power supply, featuring large toroidal transformer, and 40,000uF of reservoir capacitance, more than many modern power amplifiers.
Nice view of the ‘Elna for Audio’ main filter capacitors. These remove the ripple left over from rectification of the AC into DC and store energy for use by the circuitry.
Input end of the board, note the four dual JFET input packages, one each for left and right, +ve and -ve. Also note the array of very high-quality Elna 1,000uF electrolytic capacitors, right where they are needed, to minimise power supply impedance. There are 16 of these 1,000uF caps, again, way more than in most power amplifiers, even expensive ones.
Zoomed out a little more, we see the tops of the 8 x 1,000uF filter caps, plus the heat-sinks for the first bank of transistors.
Here we see the output buffer, with TO-220 output devices mounted to large heat-sinks, again to manage the heat generated by class-A operation.
Behind them are the second lot of eight Elna 1,000uF local reservoir capacitors. Note the two leads are for my test setup. This makes for a total of 40,000 + 16,000uF of energy storage in this pre-amp – 56,000uF in total, and definitely more than many modern amplifiers.
So why isn’t all gear made like this?

You might ask why all manufacturers don’t make things this way when these topologies are technically and sonically the best solutions? The answer is simple – it costs too much. Making 8 adjustments per preamp is itself an expensive proposition for the production line.

You might ask why all manufacturers don’t make things this way when these topologies are technically and sonically the best solutions? The answer is simple – it costs too much. Making 8 adjustments per preamp is itself an expensive proposition for the production line.

Having no capacitors in the signal path is sonically also the best way to go, but it requires DC servo circuitry for every stage, and this is also expensive to design and implement. Mirror-paired JFETs in combined packaging are really expensive and there are lots of them in this preamplifier. Add in heat-sinks for class-A operation, closely matched components at each stage needed for balanced operation, and costs just keep rising.

Accuphase have always known how to build audio equipment this way, but the best in anything doesn’t come cheap. You get what you pay for with audio gear and this preamp is a good example of that. Heck, it draws 40 watts all the time, courtesy of class-A operation – that’s more than most modern power amplifiers draw at idle!

The Accuphase C-202 Class A line-level preamplifier is one of the best kept secrets in audio.  They come up on eBay from time to time, I strongly suggest you grab one.

6 thoughts on “Accuphase C-202 Class A Preamplifier Service”

  1. Hi,

    I have a C 222, and I am planning on buying this C202. In your opinion, sonically, would that be astep up or down?

    Please share your thoughts. I would really appreciate that.

    Best Regards


    1. Hi Kal

      The C-202 is a line level only, fully balanced from end to end preamp, quite different from the C-222, which is singl-ended only. The Class A, push-pull, fully balanced config, plus the dedicated, balanced CD only input make this preamp quite unique. Truly an awesome line level only preamp, but you need a very good phono stage to match! Regards, Mike.

      1. Hi,

        Many Thanks for your reply,
        You are absolutely right, this C202, sounds amazing, warm, detailed yet smooth without sounding boring,

        I still have two questions, hope you won’t mind. Is it ok to leave C 202 on all the time?
        Second, would it accommodate those Accuphase cards in the back for analog playback, or would you suggest a separate phono stage, which would go perfectly with this preamp?
        Many Thanks for your educational and informative response Mike.
        Best Regards

      2. Totally OK to leave on all the time, though bear in mind it constantly dissipates around 40 watts due to class A operation. It does not accomodate cards, it’s a line level only preamp. You would need to choose a phono pre or pre and transformer to suit your requirements and budget, though any phono pre will interface with the line level inputs of the C-202. Cheers, Mike.

  2. Hi, Im planing to buy this pre amp but is 100v, in my country we use 120V. Is the transformer multivoltage?. Can i change it by rewiring?


    1. Hi, this depends on the individual example and you would need to check the one you are purchasing. Mine was configurable from memory, but I’d suggest checking your unit to be certain as the same model can vary in terms of being configurable or not. If not, you can always use a small step down transformer, 100 watts would be enough. Regards, Mike

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