Bogen 8417 tube conversion..? - Page 3

anatech · 31st May 2006, 12:22 AM

Hi SY,
Oh yes he would!

Seems you are a popular guy for tube fronts ends lately. Good going!

-Chris

Original Burnedfingers · 31st May 2006, 01:44 AM

Brokeback SY?

Original Burnedfingers · 3rd June 2006, 11:51 AM

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.

SY · 3rd June 2006, 12:00 PM

Teardown and rebuild, the two magic words when good iron is in the house.

Original Burnedfingers · 3rd June 2006, 12:02 PM

Anything for Nichols as far as rebuild? Rebuild to the SYclone amp

on post #10?

SY · 3rd June 2006, 12:34 PM

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.

Nichols · 4th June 2006, 08:25 PM

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.

Original Burnedfingers · 4th June 2006, 10:58 PM

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.

poobah · 4th June 2006, 11:13 PM

Find some way to get the schem up here!

Nichols · 4th June 2006, 11:18 PM

Thanks again. The Bogens are great guitar amps (I have others) and I hate to boat-anchor this one for the sake of an obsolete tube; a modern 120 watt hand-wired amp costs a fortune.

3rd June 2006, 12:00 PM	#24
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	Teardown and rebuild, the two magic words when good iron is in the house. __________________ If there's a sucker born every minute, where do the rest of them come from?

3rd June 2006, 12:34 PM	#26
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	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. __________________ If there's a sucker born every minute, where do the rest of them come from?

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31st May 2006, 12:22 AM	#21
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi SY, Oh yes he would! Seems you are a popular guy for tube fronts ends lately. Good going! -Chris

31st May 2006, 01:44 AM	#22
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Brokeback SY?

3rd June 2006, 11:51 AM	#23
Original Burnedfingers diyAudio Member Join Date: Nov 2002	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.

3rd June 2006, 12:02 PM	#25
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Anything for Nichols as far as rebuild? Rebuild to the SYclone amp on post #10?

4th June 2006, 08:25 PM	#27
Nichols diyAudio Member Join Date: May 2006	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.

4th June 2006, 10:58 PM	#28
Original Burnedfingers diyAudio Member Join Date: Nov 2002	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.

4th June 2006, 11:13 PM	#29
poobah diyAudio Member Join Date: Nov 2005	Find some way to get the schem up here!

4th June 2006, 11:18 PM	#30
Nichols diyAudio Member Join Date: May 2006	Thanks again. The Bogens are great guitar amps (I have others) and I hate to boat-anchor this one for the sake of an obsolete tube; a modern 120 watt hand-wired amp costs a fortune.