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How to convert a bogen 6L6 Challenger to Fender champ deluxe tube amp Tweed sound
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- Опубліковано 11 лют 2017
- This amp came in via mail order to D-lab Electronics. Task: convert this old relic to a cool tube guitar amp. Was I up to the Challenge? Of course! I love to repurpose/retrofit/give new life/D-labotize! I appreciate the opportunity. Plus, I am honored to be your go-to tube amp guy. Thank you to all for supporting me and my crazy antics. If I could find a way, this would be my life 24-7. TD
Wow, I'm very happy with what I see. Can't wait to get that little amp back home in Texas. Thank you so much Terry.
Cool deal man, Yes, it turned out great!
Terry, I finally got a chance to try out the Challenger amp today. Been very busy. New granddaughter was born and we have been in Dallas. I love the amp. I'm going to build a new cabinet for it.
The "Gibson sound" doesn't come from just changing the 12AX7 for the 6SL7. Gibson used different values for the preamp compared to Fender:
Gibson:
- 47k resistors for the inputs, while low pulled one 47k to ground, and high kept the input floating, both having a series 47k with grid;
- 220k plate resistors;
- 2k2 cathode resistors (first bypassed by a 20uF cap);
- 47k feedback resistor;
Fender:
- 68k resistors for the inputs, while low pulled one 68k to ground and kept the other 68k in series with grid, and high had a 1M to ground, with both 68k resistors in parallel with eachother, resulting in a 34k resistor in series with grid;
- 100k plate resistors;
- 1k5 cathode resistors (some versions have the first bypassed, others didn't);
- 22k feedback resistor;
Basically, the only thing the Gibson and the Fender circuits have in common is the output stage and the coupling caps values. The difference in the bias of both circuits make them achieve distortion at different points with different characteristics.
Now, if the sound difference is noticeable or not, is another story completely...
That's a great idea to parallel the 12AX and the 6SL. Another interesting video as always :)
Real nice Terry. What a great option for a player.
Love this stuff !!! great job !!
Upcycling old stuff is good. I'm doing a leslie speaker that came from a defunct organ.
great work
The more I play this Challenger, the more I like it. Several of my friends have tried it and love it. My friends play regularly while I play, with a band, 4-5 times a year. I put the chassis in a new cab with 1-10" speaker and it honks. I also have an 8" speaker that sounds just about as good.
Looks like we should search out more of those amps to modify!
I have another little single 6L6 Knight pa amp and I just picked up an old Meissner monoblock amp with 2-6V6's.
Just got a Challenger 33 with a bad output transformer. Getting a new 20 watt 8k OT for 6v6’s and turning it into a 5e3. Luckily the power transformer is still just fine. Funkiest smelling guts I’ve ever come across in an old amp!
Great, Thank You!!
could you please recommend a list of parts, you always have in your workshop? I really enjoy watching your videos and 'd like to heat up my soldering iron afterwards ;)
great vid!! i really wish you would get a guitar, tune it to an open chord so strumming and slide will sound decent, then play away at the testing stage!!!!!
That was a great demonstration, very clear explain add the point I be now halfway learn . I wander in if you can have a Swisher and you don’t have to replace the tub.?
cool little amp, how about a switch for the preamp tubes, 12a/ 6j or both ....and a negitive feed back gain pot..
Please Terry, provide a schematic for your mods! So unbelievably cool!
Always look forward to seeing your latest vids! Great stuff and please keep them coming!
Thank you Sir, I will document this amp build before it ships back to the owner. Thank you for your faith in me. TD
Absolutely love the "work with what you got" approach! Would love to see more of this stuff, and I bet I'm not the only one!
Followed your advice regarding signal generator, oscilloscope, and all the rest and you keep me moving along - and for an old guy like myself that ain't too bad. Like they say, "Learn something new every day and you'll never grow old."
Hats off to you Terry!
nice
Do you have a schematic for this? This is so great!
I would have kept the 6sj7 pentode for a cool vintage sound
It would be really cool to see the frequency response differences between the two pre-amp tubes using your analyzer from the other videos.
I will shoot that video as well as a live guitar demo
Hey man, just posted the video you requested on the preamp tube frequency response's
So early the video is 240p..............worth it.
Nice job! I know it's just cosmetic, but I would like to see that ugly old mic input removed and one of those beautiful black laser-engraved D-Lab front panels installed.
another great video. fix that old iron...
Good to give the old Bogen a second start in life
What's the eta / waiting period for accessing your wisdom my good sir 🙏
I now own a 15" Peavey Delta blues combo with an either defective or shitty tremolo and reverb ... unload or mod 🤔? It sure needs a Dr. Like yourself
NIce work brother...
Great vid. I've got an old Challenger from the 40's that my dad used until the early 50's. It has never been modded. Has 2 mic plus a phono. Also have his old speaker cab. Any idea where I could find a schematic. Would love to update it for my personal use. Model # C35 Serial #1094
Look up “Radio Museum” online. They have every old schematic you can imagine and will email it to you along with any other info about whatever model you look up.
nice build up
Thank you my friend.
hi id like to have shematic of this amp is it possible! thanks
If you could do a amp that has 7868s I could get some tips thanks
Where would someone start on how to actually do the rewiring after it's gutted? Is this something that an amateur could safely do if they were very careful and went step by step?
Best thing to do is reference a typical Fender schematic. See if your donor amp can support the new circuit and go from there
What happens when both pre-amp tunes are in place?
There would be too much current draw and the gain would decrease beyond usefulness.
Bogen can be had much cheaper than Fender too. D
Is there any way you could have switched between those two tubes?...thanks
It would require a 6 pole selector switch. A source of noise.
thanks
why not sintall a switch instead of swapping tubes???
The switch would have to isolate 6 poles.
Would be difficult to configure.
Unlike me.... U obviously know WTF your doin!!!! I have a 79' silver face champ.. If I replace the tubes does it need to be re-biased??? Thanx man...
Hello, Nope, not on the Champ. It is cathode biased by a resistor to ground. Should not change unless it looks baked.
D-lab Electronics thank you. If I ever opened one of them amps up I'd either do irreparable damage to the beast or get lucky and do a " I FOUND IT", on the infamous death cap!!!! But I do enjoy your videos , keep at it sir. 🎸
anybody else get nervous when d-lab sloshes the wine in the glass near people's amps? it's the amp equivalent of michael jackson dangling the baby out the window.
I do my best work after a glass
that's fine. it's the waving the glass and seeing the wine slosh in the glass near/over a customer's chassis that makes me nervous.
i do love your videos. just saying. :)
That's cool, Glad to have you on board. TD
Great work as usual. But you really need to learn how to play guitar so we can hear it (real easy huh? lol).
Yes Sir, I have limited resources here for players. I need to clone my self!