Champ clone

[burdij]

This amp can only put out about 6 Watts and was originally intended as a studio or practice amp. Six Watts is about the amount of power a healthy AC/DC radio is designed to put out. The reason for using a single relatively small speaker is so that the amp can at least have a chance to produce some kind of an overdriven sound before the transformer turns into a puddle of melted copper. Dumping 6 Watts into an array of 4 much larger speakers just means that one would end up with a low level distortion caused by the transformer being overdriven. And the distortion isn't going to a "pleasant" sounding distortion as the waveform will be very asymmetric.

 

[AnalogPackrat]

5-6 watts can be quite loud through an efficient speaker.  I don't know what kind of "AC/DC radio" you're talking about, but I'm sure such radios have really inefficient little speakers.  The crappy original 8" speakers in the champs are in the ~95dB 1W-1m sensitivity range.  I play one of mine through a large 2x12 open back cab with Eminence speakers which have 103dB 1W-1m ratings.  This makes a huge difference.  The tiny champ cabinet also allows lows (low mids even) to wrap around and cancel themselves out.  With a bigger cab the lows are extended.

Can you get throbbing loud clean tone or death metal chunka-chunka out of one?  Not really.  But you aren't going to melt the OT playing it wide open, either.  And "unpleasant?"  Ask Clapton, Joe Walsh, and others why they used champs on some of their most famous recordings.  These are great little amps..if they weren't you wouldn't see vintage 5F1 models selling for $1-2k.

A P

 

[syn]

any amp that "wont do" death metal, must be a good one ;D. O.K. I've also read that  Hendrix used to record on champ (don't know what and when).

 

[emrr]

The first Black Flag records are clearly a dimed Champ, about to give it up.  I at least duplicated that sound once by that method.

A real crazy friend once took part in a project to build a 300W Champ booster amp.  Champ output in reverse as input to an amp using forced air cooled transmitter tubes.  I wonder what happened to that thing.

 

[Neil]

I wonder what happened to that thing.

I believe I saw it in the movie "Back to the Future".  ;D

 

[emrr]

That's about what it looked like.  It was built onto a rolling cart, since it weighed several hundred pounds. 

 

[pietro_moog]

hi! did you build it?
is it working?

 

[syn]

Hi
  no, not yet, I'm collecting parts at the moment. Once I have all I need I see no reason  for it not to work ;D

 

[pietro_moog]

i'm working on this project too

 

[burdij]

This is a little amp I am calling "Champ-Plus". It is the basic Champ circuit with the addition of bass and treble tone controls and a 6C4 to make up the tone stack loss and give it a little overdrive. All the parts are mounted on a PC board. The other tubes are a 12AX7A, a 6V6GT and a 5Y3GT.

 

[syn]

looks super nice!