SOLD: Adcom GFA-535 II – Re-capped, refurbished and upgraded! $400
SOLD! But Stay tuned, I am building more Adcoms all the time.
Hi Folks, I have another ADCOM GFA-535 II for sale! As with all the amps I sell, this unit has been thoroughly refurbished and obsessed over. This amp not only sounds better than new, but I intend it to last another 30 years or more! I go way beyond a simple re-cap. Any and all parts that may potentially deteriorate have been replaced.
I take a cautious approach to upgraded components such as capacitors. I do not second-guess the engineers unless I understand why that part was chosen in the first place, and it is clear to me that the part was compromised for cost savings or ease of manufacturing. Some modern parts are better than what was available at the time, and this is another reason I choose to replace certain components.
* All electrolytic caps replaced with Nichicon MUSE and Fine-Gold audio-grade capacitors
* Power supply capacitors upgraded from 6800uF to 10,000uF Panasonic TS-HA 105C for higher current reserves, longer life, lower DCR and more ripple current capacity.
* Input capacitor changed to WIMA MKS4
* Emitter resistors changed from 5% tolerance sand-cast types to mil-spec DALE LVR 1%. These are more reliable, and frankly, prettier.
* Sealed Bournes trim-pot installed for precise bias adjustment and better reliability.
* Transistors in the critical input and VAS stages are removed, checked for matching gain and replaced if they don’t match, or have low gain. This step is important to assure low DC offset at the output, and low distortion.
* Output transistors re-mounted using traditional Kapton insulators and ceramic thermal paste. (This transfers heat a little better than the stock sil-pads)
* High-current bridge rectifiers are installed and heat-sinks attached. This helps prevents power supply droop while the amp is being run hard.
* New power switch and spark-supressor capacitor.
* New surge-protection MOV
* Snubber capacitor installed across incoming AC line to reduce RF interference
* Circuit boards are cleaned and solder joints inspected and touched-up wherever needed.
* New gold-plated binding posts
The last step is to check performance under load, stress test and set bias. The amp is run into a dummy load, and power output readings near clipping are recorded. (Approximately 80WPC into 8 ohms.) The amp is driven hard for 30 minutes, allowing it to heat up, and it should show no signs of distress. It should cool itself down in a reasonable time, and the bias should remain steady throughout the temperature range.
The amp is hooked to my studio monitors and listened to for a couple days. If performance is good, and no issues arise, I check the bias one more time, and call it done!
Cosmetically, this amp is in excellent condition, though not quite mint. There are a few light scuffs and slight smudging of the lettering in the word “Instantaneous”. (It came like this.) You can judge the cosmetics for yourself by these hi-res photos. It’s a beauty.
Unit will ship double-boxed with padding all the way around.
I stand behind what I sell, and my goal is that you have an amplifier that works amazing and sounds amazing.
Also, please see my blog at Hoppe'sBrain.com
SOLD! But Stay tuned, I am building more Adcoms all the time.
Hi Folks, I have another ADCOM GFA-535 II for sale! As with all the amps I sell, this unit has been thoroughly refurbished and obsessed over. This amp not only sounds better than new, but I intend it to last another 30 years or more! I go way beyond a simple re-cap. Any and all parts that may potentially deteriorate have been replaced.
I take a cautious approach to upgraded components such as capacitors. I do not second-guess the engineers unless I understand why that part was chosen in the first place, and it is clear to me that the part was compromised for cost savings or ease of manufacturing. Some modern parts are better than what was available at the time, and this is another reason I choose to replace certain components.
* All electrolytic caps replaced with Nichicon MUSE and Fine-Gold audio-grade capacitors
* Power supply capacitors upgraded from 6800uF to 10,000uF Panasonic TS-HA 105C for higher current reserves, longer life, lower DCR and more ripple current capacity.
* Input capacitor changed to WIMA MKS4
* Emitter resistors changed from 5% tolerance sand-cast types to mil-spec DALE LVR 1%. These are more reliable, and frankly, prettier.
* Sealed Bournes trim-pot installed for precise bias adjustment and better reliability.
* Transistors in the critical input and VAS stages are removed, checked for matching gain and replaced if they don’t match, or have low gain. This step is important to assure low DC offset at the output, and low distortion.
* Output transistors re-mounted using traditional Kapton insulators and ceramic thermal paste. (This transfers heat a little better than the stock sil-pads)
* High-current bridge rectifiers are installed and heat-sinks attached. This helps prevents power supply droop while the amp is being run hard.
* New power switch and spark-supressor capacitor.
* New surge-protection MOV
* Snubber capacitor installed across incoming AC line to reduce RF interference
* Circuit boards are cleaned and solder joints inspected and touched-up wherever needed.
* New gold-plated binding posts
The last step is to check performance under load, stress test and set bias. The amp is run into a dummy load, and power output readings near clipping are recorded. (Approximately 80WPC into 8 ohms.) The amp is driven hard for 30 minutes, allowing it to heat up, and it should show no signs of distress. It should cool itself down in a reasonable time, and the bias should remain steady throughout the temperature range.
The amp is hooked to my studio monitors and listened to for a couple days. If performance is good, and no issues arise, I check the bias one more time, and call it done!
Cosmetically, this amp is in excellent condition, though not quite mint. There are a few light scuffs and slight smudging of the lettering in the word “Instantaneous”. (It came like this.) You can judge the cosmetics for yourself by these hi-res photos. It’s a beauty.
Unit will ship double-boxed with padding all the way around.
I stand behind what I sell, and my goal is that you have an amplifier that works amazing and sounds amazing.
Also, please see my blog at Hoppe'sBrain.com
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David, I'm working on a 555 II right now! It's in really beautiful shape, so I am pulling out all the stops and doing every good mod I know. New caps throughout, even the power supply beer-cans. I am doing the relocation of the power supply wiring and capacitors, to clean up and shorten the wiring. 14ga power plug, nice fat binding posts, etc etc. Obsessively detailed.
It'll be pretty much the same as this 555, except I won't be doing the internal fuse modification.
The Adcom GFA-555 Mark One-and-a-half. | Hoppe's Brain
It should be ready in about a week. $850. I've also got a GFA-545 II that will be ready for sale tomorrow.
Thanks,
Chris
It'll be pretty much the same as this 555, except I won't be doing the internal fuse modification.
The Adcom GFA-555 Mark One-and-a-half. | Hoppe's Brain
It should be ready in about a week. $850. I've also got a GFA-545 II that will be ready for sale tomorrow.
Thanks,
Chris
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