Its too bad that no one seems to want to share any ideas for the Bogan. Given the performance specifications for the output transformer the piece looks like it has some hope. I am no expert but it looks like 6550's would work with a re do of the bias circuit.
The bias circuit that is there seems to balance the two pairs to each other and you need individual adjustment for each output tube. Yes, its extra work but it allows for the tubes to age.
The bias circuit that is there seems to balance the two pairs to each other and you need individual adjustment for each output tube. Yes, its extra work but it allows for the tubes to age.
Depends on the output tubes he chooses and his degree of ambition. 6L6 types need a lot of drive, so a constant-current diff amp input followed by a voltage amp stage (direct coupled) would be my first choice. If I were particularly ambitious, I'd add source or cathode followers between the driver and output tubes to get a measure of AB2 and to protect against blocking distortion. Morgan Jones's Crystal Palace input stage is a good (if overkill) example of the topology.
The SYclotron is a fun novelty but not for universal use. I like it in amps with moderate drive requirements.
The SYclotron is a fun novelty but not for universal use. I like it in amps with moderate drive requirements.
Thanks to burnedfingers for the proactivity. I appreciate the replies but I'm not experienced enough to translate the suggestions into a circuit. If there was a simple solution like, "See this thing? Replace it with that thing" then I could do it, otherwise this looks like too daunting a task for my skills. If anyone would be interested in the amp or a DuKane Medallion (two 8417 tubes, 60W out) please contact me. Both amps have had all the paper caps replaced and work fine. These are great guitar amps just as they are... Thanks again.
Don't give up yet as there might be more activity to come. Some of us started out here knowing very little and only slightly more now. If you are willing to be patient and stay on here you will learn also. There are some good knowledgeable people here that will work with you.
I am hopefull that some of these people will chime in here soon with some suggestions for your Bogan rebuild. I think the Bogan is ripe for a face lift and would make a worthy amplifier to have.
Don't throw in the towel yet.
I am hopefull that some of these people will chime in here soon with some suggestions for your Bogan rebuild. I think the Bogan is ripe for a face lift and would make a worthy amplifier to have.
Don't throw in the towel yet.
I believe the image hosting sites will accept pdf's. Post your pdf there... copy the URL/link... and embed it here.
www.imageshack.com
Edit: O.K. that's poor example... but there are others...
www.imageshack.com
Edit: O.K. that's poor example... but there are others...
Bogen M120 Schematic Image
Thanks to poobah, good idea.
If all goes correctly, the schematic should be here:
http://www.uploadfile.info/uploads/71c4fcbd7b.jpg
Thanks to poobah, good idea.
If all goes correctly, the schematic should be here:
http://www.uploadfile.info/uploads/71c4fcbd7b.jpg
I emailed Triode Electronics and received this much:
"...the 8417 tube is a high power beam power tube and you probably could convert to 6550 pretty easily. The tubes both have the same pinout so you wouldn't have to rewire the sockets. the 6550 cannot handle quite as much screen voltage so I'm not familiar with your circuit but you may have to drop that a little..."
That's all, maybe it's helpful.
"...the 8417 tube is a high power beam power tube and you probably could convert to 6550 pretty easily. The tubes both have the same pinout so you wouldn't have to rewire the sockets. the 6550 cannot handle quite as much screen voltage so I'm not familiar with your circuit but you may have to drop that a little..."
That's all, maybe it's helpful.
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