I had just got this Bogen CHA-33 Amp, Challenger series running 2, 5U4s, 2, 6L6s, 2, 12AX7s and a 6AV6 tube,
5 Electrolytics and about a dozen regular caps the thing plays pretty nice, I added a 1/4" Mono jack on the back for easy speaker plug in, wired to the rear jumper screws so changing Ohms to the plug in speaker is easy, I also went and removed the two original Microphone jacks since they are hard to come by and added two more 1/4" Mono jacks for inputs and the 1/4"xRCA adapters are pretty common.
Then I just could not leave the cage looking old and ratty so I sprayed a coat of gloss black since It was something I had laying around, While it looks tons better, I think it needs to be Flat or Semi black instead of gloss, So I will repaint some other day.
It's rated at 33 Watts and I really don't have any speakers which can handle it, But I did crank it up a while on a Bose 901 speaker and it does have better sound than I thought it would running that smallish out-put transformer...
Now I have to find some tube shields before I consider it done.
Just thought I would share.
I am open to ideas on cage colors too.
Too bad they have such ugly knobs, If they weren't all original I would replace them with Chicken Head knobs which I think look best on Amps,
Thanks for looking.
Peter and Eileen

Congratulations on a good job. I hope that amp gives you many useful hours. Keep up the good work.

Larry

Looks real nice!

I'd be careful running 5U4s because it looks like it calls for 5Y3s, and they draw a lot less filament current that 5u4s do.....times two in your case.

Btw those knobs clean up fairly well if you soak them in hot soapy water and then clean with a toothbrush. It is harder finding D-shaft replacement knobs than round, and they need to be oriented just right.

I've got a couple CH35s waiting to get some love. Lower power than yours, which again looks very nice.

RWood

OK, I was going by my lousy memory, There is a pair of 5Y3s in there. I went and repainted the cage in a nicer color which I am happy with, WIll add more pics tomorrow,
It's been fun tinkering with the Amps, No tuner cap grommets, No straightening plates, But there are sure a lot more Lytics and paper caps in these Amps as well as resistors and the like but when they are all done and the wife can plug her iPhone in and listen to her favorite music all is right with the world.
Lord knows we have enough consoles and table top sets for several houses
Now I want to play with a pair os nice single ended Amps.
What are your opinions on the Bogen Amps?
Were they designed for straight PA. use?
Peter

Nice set, yes primarily for P.A. but good enough response to be pleasing for music and voice for the average ear. Rugged and venerable iron, and nice to have sweet amp for anyone.

I have a couple Bogens that I run guitar through. sound great. just the right kind of distortion. tons of power. they are engineered very well and built like a tank. one has a pair of 6SF5 into 6SL7 into p/p 6L6 about 50W. another has a pair of 6SJ7 into se 6L6 about 10W. had a couple more that I sold

Well I had it running for several hours and no smoke yet.
Must be OK.
What mods do folks do to make them Guitar amps?
Peter

Basically rip out everything before phase inverter, steal a fender, ampeg, or whatever preamp circuit and clamp a really high voltage cap across the output winding to kill harmonics. Gotta be real careful with jacks and grounding. Best take a look at "Star Grounding" techniques. Of course fuse the set, and use a 3 wire mains connection w/wo GFP, lose the potential "death capacitor" and check in often.

Repaint and I like it,
Kinda a Sage greenish color.
Nice and clean looking,

I have several Bogen PA amplifiers, very rugged with great sound. For better sound from the iPhone, if it has a 30-pin connector on the bottom, get an iPod Dock cable which has the 30 pin connector on one end and two RCA audio jacks on the other. Amazon has them. This gives a line-level output, use a Y-adapter to combine the channels and feed it into the Phono input on the back of your amp. This should sound better than the headphone jack.
Don

Neat looking amp.I like the dual 5Y3's.

Regards,
Swanson