digitalguru
New member
I have owned a couple of HF87's in the past and always loved their sound. The last HF87 I owned I had done the 12AX7 power supply upgrade but left the amplifier cathode biased. That was at least 6 or 7 years back. After reading all of the mods on this forum regarding Dave's NFB loop mods, EFB (tm), fixed bias, etc... I decide to start one from scratch.
Early last week I gutted a nice chassis. Thursday I spent the day installing new sockets, the 12AX7 power supply and the fixed bias circuitry. I used bias and balance pots for each channel as I prefer that arrangement to a bias adjustment for each tube which I've done on amplifiers before. Friday morning I installed the input jacks, gain pots and 12AX7 circuitry. Haven't done anything else as I want to paint the transformers, which I'll do early this week. I plan on upping the values on the top mounted capacitors, upgrading the NFB loop values and lastly installing EFB. I have all the parts here so its just when I get time. I'm going to run KT77's in the amplifier.
Anyway, I'm having a good time with this HF87 and will post photos when I finish it up. I know there are a lot of people on this forum enjoying the HF87 with mods so looking forward to getting this one up and running
Early last week I gutted a nice chassis. Thursday I spent the day installing new sockets, the 12AX7 power supply and the fixed bias circuitry. I used bias and balance pots for each channel as I prefer that arrangement to a bias adjustment for each tube which I've done on amplifiers before. Friday morning I installed the input jacks, gain pots and 12AX7 circuitry. Haven't done anything else as I want to paint the transformers, which I'll do early this week. I plan on upping the values on the top mounted capacitors, upgrading the NFB loop values and lastly installing EFB. I have all the parts here so its just when I get time. I'm going to run KT77's in the amplifier.
Anyway, I'm having a good time with this HF87 and will post photos when I finish it up. I know there are a lot of people on this forum enjoying the HF87 with mods so looking forward to getting this one up and running