Sold: Fully Restored ADCOM GFA-555 II

UPDATE: 08-04-2017: Looking back, I never should have sold this so cheaply! I was seriously under-charging for my work; a common mistake with new businesses. This amp represents several full days of work and a high parts cost. I would now charge around $1300 for this same amp.


Hey folks, I have another 555 II ready for a new home! It’s got the full package. All new capacitors throughout, including the power supply caps. Matched input transistors, local supply bypasses, etc etc etc.

This one is in excellent cosmetic condition. There are a couple of dings that I have touched up, and are hardly noticeable, but since the amp is not totally “mint”, I am selling it for $820 instead of the usual $850. (I am very picky about this stuff.) Please click on the hi-res photos to see for yourself.

A beautiful face. There is a small ding in the middle of the right side. It’s been touched up and is hard to see, but this is why I am taking $30 off the price.

This is a thorough refurbishing! I want my amps to last another 30 years. The entire amp has been stripped to the chassis and rebuilt from the ground up. Every component has been checked, every solder joint inspected, and every wire neatly routed. All electrolytic capacitors have been replaced with audio-grade types from Nichicon, WIMA or Panasonic. Even the big power-supply filter capacitors are new, something many restorers leave out, or charge extra for, because they are expensive.


    • Improved power-supply layout with thick copper bus-bar shortens wires and reduces clutter and radiated noise. (New capacitors are smaller so I can mount them closer.)
    • Transistors in the critical input stage are carefully matched for gain. This step is important to assure low DC offset at the output, and low distortion.
    • Local power-supply bypass capacitors added to the input board for greater power-supply smoothing.
    • AC noise-snubber capacitors added to bridge rectifiers.
    • Driver transistors changed to 250V NJW1302/1381 for greater voltage headroom. The originals are 140V parts, and are known to fail when driven hard at high-frequency, due to the power supply swing of 170V.
    • Output transistors are original; the very excellent Toshiba 2SD424/554.
    • Circuit boards are cleaned and all solder joints are re-flowed and inspected.
    • New power switch and spark-supressor capacitor. (Most Adcoms do not have soft-start circuits, and are hard on power switches.)
    • New, sealed Bournes bias trim-pots.
    • Heat sinks added to the Class-A driver and bias transistors for greater reliability.
    • Dale LVR 1% 5W emitter resistors replace the original 5% sand-cast resistors.
    • 50A bridge rectifiers with snubber caps installed across AC input
    • High-temperature and high-endurance capacitors used throughout.
    • 14ga Power cord with heavy-duty plug.
    • New gold-plated and binding posts.

I measured 260WPC at 8 ohms and 340WPC at 4 ohms just before clipping.

Listening tests were done over three days with a pair of JBL 4208 studio monitors. Sound is superb as expected.

Thanks for looking! Please contact me here if you’re interested, or have any questions.

5 thoughts on “Sold: Fully Restored ADCOM GFA-555 II

  1. Yellow from Kentucky, I suspect I am late to the party on these wonderful amps that have been thoroughly refurbished/restored. Is there a chance you will have another for sale in the future? Sincerely, Robert, Kentucky

    1. Sorry, probably not. I’m just refurbishing amps that people send to me. You could buy one and join my waiting list and that’s about 4 months at the moment.

  2. Hi again, so now I have an opportunity to buy a nice and functioning GFA-555. The earliest version I believe. It is the amp that checks all the boxes for me. Aside from shipping, what might be a range (lowest and highest) of prices that reflect perhaps the least amount of restoration and the maximum amount of restoration? I hope that makes sense. Sincerely, Robert

    1. Hi Robert! Yes I am doing refurbs again, and I have about. 4 month wait time. Go ahead and buy the amp, and let me know via the contact form at the top of my page, and I’ll save you a spot in the queue. I won’t have you ship until I am close to actually working on it.

      I don’t offer any different levels of refurbishing. Every amp gets the same treatment with an entirely new input board. The only options are whether to replace the power supply capacitors or not, and whether or not to go with the ‘Smart Soft-Start Power Supply’ or just stick with the stock arrangement. Thanks, let me know!

    2. Hey Robert – I have the same model as you. Chris did the full monty on mine a while back, being so thorough that he was able identify unrelated issues and provided fixes. All I can say is don’t hesitate. Every time I connect higher level components to it, the amp performs at a higher and higher level. If you plan to keep your 555 for good, don’t hesitate to let Chris make it a truly superb amplifier.

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