I have been dragging my feet on this decision for some time but have decided it's time to let go of my Allen Model 75 KT88/6550 mono amplifiers. These had been the heartbeat of my main system for several years but it's mostly 2A3 and 300B amplification now a day.
These Allens have been recapped with Solen and electrolytics have been replaced. Any out of spec resistors have been addressed also. Additions consisted of off/on switching, power-on indicator lamps and heavy duty power cords. I added the bases as a temporary measure to dress them up a bit but liked it so much, I never changed them out. I would show the going's on under decks in these pics but I made the bases in such a manner that in order to do so, would require losing them in the process. If necessary, I will disassemble them.
The work was done here in town by a local retired Navy electronics tech. He is very knowledgeable, thorough and did a wonderful job. I provided him with pages of internet notes on the slight circuit mods needed that make the 75's into great audio amplifiers. The stock 75's without them are nice but possess too much gain (from what I understand) with out them. That was addressed and the results are very, very nice.
NOTE: If you see that I have added pics of the underside, this means the bases have been removed and will remain that way. You will need to make your own if you choose to.
Very nice sounding amplifiers with 75w/ch output using either KT88 or 6550.
Tube compliment/amplifier:
2- Penta Labs KT88
2- 6SN7GTB
1- EF86
1- 12AY7
I have the schematic for these somewhere that notes the circuit mods and biasing info.
$ 1600.00 OBO + shipping from 55119
These are heavy amplifiers so plan on approx 65lbs or so per container
Thanks, RC
These Allens have been recapped with Solen and electrolytics have been replaced. Any out of spec resistors have been addressed also. Additions consisted of off/on switching, power-on indicator lamps and heavy duty power cords. I added the bases as a temporary measure to dress them up a bit but liked it so much, I never changed them out. I would show the going's on under decks in these pics but I made the bases in such a manner that in order to do so, would require losing them in the process. If necessary, I will disassemble them.
The work was done here in town by a local retired Navy electronics tech. He is very knowledgeable, thorough and did a wonderful job. I provided him with pages of internet notes on the slight circuit mods needed that make the 75's into great audio amplifiers. The stock 75's without them are nice but possess too much gain (from what I understand) with out them. That was addressed and the results are very, very nice.
NOTE: If you see that I have added pics of the underside, this means the bases have been removed and will remain that way. You will need to make your own if you choose to.
Very nice sounding amplifiers with 75w/ch output using either KT88 or 6550.
Tube compliment/amplifier:
2- Penta Labs KT88
2- 6SN7GTB
1- EF86
1- 12AY7
I have the schematic for these somewhere that notes the circuit mods and biasing info.
$ 1600.00 OBO + shipping from 55119
These are heavy amplifiers so plan on approx 65lbs or so per container
Thanks, RC
