Bogen CHB-50 Tube Amplifier Conversion, ep 1: Tour and Mod Plans
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- Опубліковано 9 вер 2020
- In this first episode I go over what a Bogen CHB-50 PA amplifier is and what it's features are. Then I go over my planned modifications in order to change it from a tired old public address amplifier into a very flexible studio tool that can work with many instrument sources without adapters. The finished amp will have way more tone than before while still retaining it's Bogen soul. The results are fantastic with these guys! This series will continue with part two, where I tear the original wiring and parts out, then install my own modified circuit into the bare chassis.
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Love hearing your voice again buddy!
Whoa! Grant! Dude! I looked you up before and couldn't find anything. I was curious what you were up to and what you did with your incredible art talent? Mine was spread around to weird disciplines that weren't traditional art paths. But I'm back to drawing full time now, like a freaking monk. Monking Freak? Somewhere on that spectrum. Look me up on deviant art as Tablebeast. And join Deviant Art!!!
About 8 years ago I was digging around in my old closet from when I was a kid and found my old Bogen CHB35A that actually used to belong to my dad back in the 70's, but needless to say it was in VERY bad shape.
So bad that the ONLY thing I used was the metal chassis and metal cabinet. So I did exactly what you said you're going to do (did) with yours.
I used a Fender Princeton PT hooked to a 5U4 rectifier for power.
Then I used a 50w Marshall OPT with EL34's driven by a long-tailed-pair 12au7 phase inverter.
Then I designed a "potentiometer adjustable" fixed biasing circuit with it's own seperate small power transformer on wich I wound the secondary winding myself.
Then I looked around and desided on the Fender Bantom Bass amp preamp circuit consisting of two 12ax7's.
And now I just gotta say, it's got the one of the best sounding cleans tones I've ever heard in my life, it's even dead silent when you stop playing and take your hands off the strings.
It's clean tones are even better than the cleans on my, (gulp), 6100lm 30th aniversary Marshall...
Bantam bass preamp, huh? Hmmm,
I’ll have to check that out.
I've got the chb35a converted to guitar 🎸 amp, 2 7868 tubes great clean tone and mine has a regular and hot channel.
I need to dust this off and redo the lost final episode. I don't know where the footage went, but I didn't feel like redoing it at the time. Amp should be awesome, from what my dusty memory tells me!
I have heard that Bogen amplifiers were primarily used in educational settings. Some of these were used for school intercoms, elementary school cafeteria PA systems, and things like that.
Indeed, not too many of them had very exciting lives. I’m here to change that!
Nice work man. I've got The same amp and I'm going to try to do exactly as you did but any way you can point me to where I could get a readable schematic for this model? Also, I was hoping to hear an example of it being played but I did not see that in part 4. Thanks
The chb35a schematic is almost exactly the same. I think the conjunctive filter on the output tubes is different, but you’ll probably rip that out anyway. I always do. Chb-35a schematics are all over the place. I’ve seen seems for the 50 before, but it’s significantly harder to find and, for some reason, a much rarer amp as well.
I've got a Bogen CHB 100 from the mid 70's it's got 4 7868's 6eu7, 12 ax7, and 6c4 and I've got schematic... Want to use it for cassette deck or turntable,, I need help!!! Everything looks mint in there , nobody's worked on it I installed 2 switchcraft jacks hooked up spkrs . And..... Over and over the 7watt 750 ohm resistor goes up in flames I've changed it out 3 more times larger watt values.... Same thing, your help if you can l would greatly appreciate. Thanks .
First off, if you’ve only got the one amp, then you’re only going to be able to use the amp in mono. Second, 100 watts a tubes is very, very loud! Even 35 or 50 is too loud for this application, in my opinion. Third, that Bogen of yours is a poor choice for a hifi amp as it is very much NOT hifi. For optimal home listening pleasure, you’d be better off with a stereo low watt amp. 10 watts per channel would be plenty in push/pull, but even 5 watts in single ended mode would fill your listening space with beautiful music at a comfortable volume. Now, as for your resistor, my guess is something has failed or otherwise shorted out. Try to find the defect rather that constantly replacing that resistor. Chances are that resistor failing is protecting one or both of your transformers. Message me at tablebeast@me.com and I can help further.
Jesse did i here you say in a video that your located in north carolina?
Forest City, NC
I have a Bogen CHB35A and need to replace the electrolytic can capacitor 40/20/10/10
Any suggestions on where to purchase one
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