![]() Installed original Hammond 7591s that were in the H100 amp and was able to balance bias much better but I think circuit could benefit from individual bias adjustment mod IBAM that many of you know.īut the bottom line is that this OPT is capable of producing decent sound and circuit does not appear to cut frequencies much if any. GE 7591 power tubes that amp came with are running very hot and pulling too much current at given bias voltage making me back off variac to the point where distortion is too obvious. 78 are same tubes with different base, correct? ![]() Will OPT handle the gain if 7247 is replaced with 12AX7? Of course circuit will have to be modified for that but it could be borrowed from Dave G's modified Fisher 400. I'm not impressed with the gain but it might still be very weak 7247 PI tube. Lucky because I'd condemned circuit fault otherwise. But main amp is GOOD! I wired one of the RCA jacks directly to amp input(10k resistor on pin 5 of 7247 tube) I went through all 7247 tubes I had to only find one that works! So I pulled rectifier tube for that channel and eventually all tubes from that channel. If you are looking for a hammond service manual for your organ, you can download a free PDF file from Audiofanzine, a website dedicated to music gear and instruments. One of the resistors on 4 section can burned up. I turned it of and flipped amp to inspect. ![]() 6gw8 channel started to crackle at about 80v. Powered up with variac with all 3 original speakers connected.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |