Adcom, GFA-5800 & GFA-5802
I have read in many different articles that he did design the both of these power amps, GFA-5800 & GFA-5802. Is this not correct? When people are selling these power amps they advertise this fact. Also I have an article from December 2001 audio/video revolution, comparing the 5802 to Krell and Mac stating it is a Nelson Pass Design. So his influance went further than the 555 & 585.
I have read in many different articles that he did design the both of these power amps, GFA-5800 & GFA-5802. Is this not correct? When people are selling these power amps they advertise this fact. Also I have an article from December 2001 audio/video revolution, comparing the 5802 to Krell and Mac stating it is a Nelson Pass Design. So his influance went further than the 555 & 585.
mosfets...
Much like his 555 design provided a starting point for the 5x5 amps. I think Nelson made an initial design for Adcom that seeded the mosfet generation of amps. Perhaps he'll comment on which, if any, of the current models are his work.
IIRC Based on marketing material I read from their introduction, the first mosfet amps Adcom made were for use in cars, though the car line didn't make a reappearance after the initial lineup.
Though Adcom are happy to publicise NPs initial involvement, they are much quieter about the point of divergence, when they've modified his designs to be unrecognisable. I wouldn't assume any of the current models are in any way representative of an NP design, unless you hear it from the man himself.
Stuart
Much like his 555 design provided a starting point for the 5x5 amps. I think Nelson made an initial design for Adcom that seeded the mosfet generation of amps. Perhaps he'll comment on which, if any, of the current models are his work.
IIRC Based on marketing material I read from their introduction, the first mosfet amps Adcom made were for use in cars, though the car line didn't make a reappearance after the initial lineup.
Though Adcom are happy to publicise NPs initial involvement, they are much quieter about the point of divergence, when they've modified his designs to be unrecognisable. I wouldn't assume any of the current models are in any way representative of an NP design, unless you hear it from the man himself.
Stuart
nope
the 565 has a vast collection, well 10 pairs anyway, of toshiba bipolar output transistors. 2sb424/2sd554. I think these are discontinued now, but the spiritual successor is probably something like the mj15003/4 pairs from on-semi.
I had 2 pairs of these in the distant past, liked them a lot after they had been playing for half an hour or so, seemed like something in the mix had to be hot before everything was really jamming.
Through a couple of accidents with electrostats that have lousy transformers, a buddy cooked a couple of these, so if you fry your outputs (not sure how you'd do this), as opposed to the driver PCB, I'll be able to sell you a complete set for one or two amps, if you decide to rebuild...
Stuart
the 565 has a vast collection, well 10 pairs anyway, of toshiba bipolar output transistors. 2sb424/2sd554. I think these are discontinued now, but the spiritual successor is probably something like the mj15003/4 pairs from on-semi.
I had 2 pairs of these in the distant past, liked them a lot after they had been playing for half an hour or so, seemed like something in the mix had to be hot before everything was really jamming.
Through a couple of accidents with electrostats that have lousy transformers, a buddy cooked a couple of these, so if you fry your outputs (not sure how you'd do this), as opposed to the driver PCB, I'll be able to sell you a complete set for one or two amps, if you decide to rebuild...
Stuart
Actually the successors to the 424/554 were the 1302/3281 both perforated emitter BJT's.
The 15003/4 and 15022/23/24/25 were powerbase MOT's, very tough cookies but not the same hfe as the Toshiba's.
Toshiba then sold the perforated emitter tech to ON who then made the 2119x's and all 1302 variants.
The 15003/4 and 15022/23/24/25 were powerbase MOT's, very tough cookies but not the same hfe as the Toshiba's.
Toshiba then sold the perforated emitter tech to ON who then made the 2119x's and all 1302 variants.
I was an Adcom dealer when the GFA 1 came out. It is a cross-coupled dual-differential input (like a Leach) that is bridged.
For the replacement of the 555 I had suggested a straight rip of the Leach with more outputs.
Walt had published that he had completed a Super Leach (series-connected outputs) a few years prior to this, and his comments were favorable on it. With newer high voltage outputs available, and the willingness to use more of them, series connection is not needed. Of course working for an IC company,he had to toss in a DC servo, and it is a better design than any I had seen before.
For the replacement of the 555 I had suggested a straight rip of the Leach with more outputs.
Walt had published that he had completed a Super Leach (series-connected outputs) a few years prior to this, and his comments were favorable on it. With newer high voltage outputs available, and the willingness to use more of them, series connection is not needed. Of course working for an IC company,he had to toss in a DC servo, and it is a better design than any I had seen before.
gfa 565
Hello everyone, I am new to this and Adcom. Through research, I purchased a 555ii and love it. Now considering a pair of 565's to drive my fronts. Looking for ANY feedback(no pun intended) on these mono blocks. Are these as good as the 555ii's? I'm hoping so but wanted to hear what experienced people have to say, and what the general concensus is on these. Thanks for anyone willing to take some time and help me out, Jim.
Hello everyone, I am new to this and Adcom. Through research, I purchased a 555ii and love it. Now considering a pair of 565's to drive my fronts. Looking for ANY feedback(no pun intended) on these mono blocks. Are these as good as the 555ii's? I'm hoping so but wanted to hear what experienced people have to say, and what the general concensus is on these. Thanks for anyone willing to take some time and help me out, Jim.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.