My first amp build - Champ/Deluxe hybrid - almost done...

Discussion in 'Amps and Cabs' started by Deaj, Feb 26, 2006.

  1. Deaj

    Deaj Member

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    I thought I'd post a few pics of my first amp build (almost complete). It's a single-ended, class-A design. The output section is based on a blackface Fender Champ with the tone stack from a blackface Deluxe. I added a mid boost based on the one in a Super Champ. The transformers are from Allen Amplification. It will operate with a 6L6, EL34, or 6V6 output tube. There is an extra preamp tube socket, heavy duty switch, and an extra pot installed for future mods (extra gain stage / lower B+ voltage or pentode-triode switch / mid control or master volume or presence?). Unfortunately the power transformer is damaged (short in the B+ winding) and needs to be replaced so I won't get to hear it until I order the new tranny and install it. I'm looking forward to finishing it so I can tinker with it.

    Here are the pics:
    [​IMG]

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  2. Deaj

    Deaj Member

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    The chassis is a Hammond. This one didn't start as a kit. It is based off of a Kevin O'Connor Champ circuit layout with a couple of tweaks. I ordered most of the parts through Antique Electronics Supply. I ordered ALOT of parts as I have every intention of building other amps in the future.

    As it has been 2 years since I have messed with it I couldn't quite remember where I put my schematic and layout drawings. So I pulled the O'Connor book off the shelf and went over the circuit carefully. I made several errors that resulted in the death of both transformers.:(

    David Allen of Allen Amplification was very helpful! This is the second time I've spoken with David - both times he was very helpful and a genuinely nice guy. Thanks David!

    I've corrected the problems with the circuit and I believe I'll have a working amp once I get the new transformers and install them. I'll post an update and sound clips when complete.
     
  3. pepi

    pepi Member

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    Very nice work :RoCkIn
     
  4. gkoelling

    gkoelling Member

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    That looks real nice. What kind of cab/speaker are you going to build for it?
     
  5. Deaj

    Deaj Member

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    Thanks guys!

    I have a spare 8ohm G12-65 sitting around and so I'll probably start with it. I'll build a 1x12 combo box for it when time allows assuming it sounds good enough to warrant the effort and cost of materials :D . For test purposes I'll send the output to the speaker in my ODS combo.

    Good news: the OT is almost certainly alright. I'll order a new PT from Allen tomorrow and wire it in when it arrives.
     
  6. Deaj

    Deaj Member

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    I received the new power transformer yesterday and installed it. All voltages looked good, looked right with the rectifier installed too. I loaded the amp up with a 6L6 and a 12ax7 and plugged in a speaker...

    It works! Woohoo!

    It didn't sound that great (sounded good though :). There were two variables that I did not have the opportunity to check. The 12ax7 was not in my spares stock so I suspect it to be bad. The speaker I used to test is in my Fuchs combo and it is wired for reverse polarity.

    I only had a moment to give the amp a play test. We're going out of town this weekend and so the amp will have to wait until sometime this coming week.

    Have a great weekend all!
     
  7. RL in Fla

    RL in Fla Member

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    +1 on David , and his trannies are top-notch .

    Great build job . ( try a Brimar 6V6 in it from Mike at KCA ;) )
     
  8. phsyconoodler

    phsyconoodler Member

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    Impressive looking build!Your workmanship is very nice.I'd be willing to bet it sounds as good as it looks!
     
  9. Deaj

    Deaj Member

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    Thanks guys! I'll try to get sound clips posted in a few days.
     
  10. Deaj

    Deaj Member

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    Well, it's working now. I just finished putting it back together this evening. This test file is through an unmounted (no cabinet) 8ohm Celestion G12-65. I plugged my strat in, stuck a mic over the speaker, and recorded for about 30 seconds. It doesn't sound fantastic but it sounds pretty good. It's not as harmonically rich as many Champs I've played - I have some tweaking to do.

    Here's the clip:

    http://home.centurytel.net/flanneldrawers/homebrew_champ_test.mp3

    What do you guys think? How does it sound so far?

    Thanks for the feedback!
     
  11. StompBoxBlues

    StompBoxBlues Member

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    I can't listen to it now (I'm at work) but just sayin'....
    Playing through a speaker with no cabinet whatsoever, I am no expert but it seems like that couldn't tell you very much about how it sounds really.

    I mean, the cabinet changes a LOT of things doesn't it? The baffle alone (or is it mounted on a baffle?) probably is like the difference between an electric guitar unplugged and an acoustic guitar right?

    I sure wouldn't try adjusting for tone until I had that thing running into a cabinet.

    What if it is perfect now (if it were mounted) and you adjusted it so it sounds good with no cab, and then put it in a cab and lose the sound?

    How does it seem lacking or different?
     
  12. Deaj

    Deaj Member

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    I have listened to the amp through my Fuchs combo cab/speaker and, though a long ways from a Champ configuration, it did give me a point of reference. There isn't as much gain as there should be and the amp will only break up with a humbucker pushing it. It stays clean with the single coils. I don't think it's as loud as a Champ should be (though I don't have one to compare to). This is where I feel tweaking needs to be done.

    I recorded with the unloaded speaker because it was close at hand in my recording room and the Fuchs was not. I had just a few minutes to record and post the file last night. The recorded tone represents the tone of the amp very well.
     
  13. Grun

    Grun Member

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    Cool! Looks like lots of work. Let us know how it sounds!
     
  14. JJman

    JJman Member

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    It looks like you have a resistor coming off the rectifier's output? I've used one on 2 of my amps to reduce overall B+ but that looks like a 2 or 3 watter? If that's what it's for, I would measure the dissipation to see if you need to upgrade to a 5 watter.

    How's the sound when cranked? I did a few "mods" to the 5F1 circuit on my homebrew to increase gain. Negative feedback switch and bypass cap on preamp. It's suprising how much gain you can get from one 12ax7 and one 6v6.

    http://www.geocities.com/jjsant/champo_sm58.mp3
     
  15. Damon

    Damon Member

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    Sounds great to me, Deaj. Very quiet so nice job on the wiring and layout. What were the settings for that clip?
     
  16. Deaj

    Deaj Member

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    Thanks! I had all controls set to 12 o'clock I believe.
     
  17. Deaj

    Deaj Member

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    That sounds great!

    Those pics were taken before the final build. The resistor in question was removed at some point prior to the amp working fully.

    I actually wasn't too impressed by the tone from my build. I tried several tweaks, one at a time, and still didn't particulary like what I was hearing. The last one was to remove the tone stack altogether resulting in something much closer to a 5F1. This yielded the most pleasing tone to my ears. I could have stuck with it but decided to disassemble the amp and build a 5F1 instead. I completed the amp last night and it sounds worlds better than the 'frankenchamp' it replaces. The new build is still tidy but I wasn't as meticulous. I plan to mess with lead dressing to see how the sound of the amp is affected. I also plan to do some tweaking in this one and I built it to make it easier to work on.

    The 5F1 I just completed kicks A$$!!!! I really need to get a speaker more fitting for this amp. There is a little bit of hum (not bad really but more than I want) with the new build that I haven't taken the time to isolate and resolve yet. It isn't affecting the amp's tone and I was too jazzed just playing through it to be bothered with troubleshooting. Through the Celestion I'm using this thing sounds a little like Leslie West's tone on Mississippi Queen - kick a$$! I'll post a sound clip when I have isolated and resolved the hum.

    I think that the first project was educationally valuable but I suspect I was biting off a bit more than I was able to chew. I should have started with a stock BF Champ circuit and experiment with that once complete. The layout changes, tone stack changes, etc. left too many unknown variables for me to deal with as an inexperienced tech. On the plus side I learned quite a bit having to find and resolve my own mistakes and tweak the circuit to improve it.

    I'll use this amp to experiment with as I'm starting with a great sounding amp. I'm interested to see what can be done to tailor the tone and drive. What fun!

    I'm feeling alot more confident at this point and I'm really enjoying this. Thanks for the feedback guys!
     

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