FROM GLASS AUDIO, 1992....
CLICK HERE
INTERESTING MODDED FENDER CHAMP ARTICLE
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MoreCowbell
- Transistor Tuner
Information
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MoreCowbell
- Transistor Tuner
Information
dave_b wrote:Thanks, MC. I just can't resist looking in root directories.
or to go one step further....
http://www.diycustomamps.com/images/
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bajaman
- Old Solderhand
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I recently fixed a HARP II small blues harp custom built amplifier for my friend. It was a very well made and slightly modified Fender Champ 5F1 schematic.
Changes: 12AU7 replaces the 12AX7
500k log pot and 22n 600v film capacitor from top of volume control to ground (plus a 22k resistor in series to limit the high cut response)
33uf 450v main filter capacitor, then 10k dropper resistor to 10uf 450v filter capacitor (screen supply), then 41k dropper resistor to 10uf 450v (preamp supply)
Output transformer has 4 and 8 ohm connections - 4 ohm to Ted Weber 8inch signature series alnico speaker, 8 ohm tap is feedback connection.
output terminal feeds a 22ok resistor to a direct line out socket ( 100k resitor from direct out to ground.
It sounds amazing on it's own and using the direct line out to a PA system
AND - it coes not feedback and squeal like a lot of amps can do with blues harp players.
cheers
bajaman
Changes: 12AU7 replaces the 12AX7
500k log pot and 22n 600v film capacitor from top of volume control to ground (plus a 22k resistor in series to limit the high cut response)
33uf 450v main filter capacitor, then 10k dropper resistor to 10uf 450v filter capacitor (screen supply), then 41k dropper resistor to 10uf 450v (preamp supply)
Output transformer has 4 and 8 ohm connections - 4 ohm to Ted Weber 8inch signature series alnico speaker, 8 ohm tap is feedback connection.
output terminal feeds a 22ok resistor to a direct line out socket ( 100k resitor from direct out to ground.
It sounds amazing on it's own and using the direct line out to a PA system
AND - it coes not feedback and squeal like a lot of amps can do with blues harp players.
cheers
bajaman
I scanned and posted that article. Kudos to Audio Amateur for giving me permission to republish it. That amp was one of the first amps I laid out and built from scratch.
The article has good information on modding SE amps. There was a lot of thought put into the design.
Having said that, the amp sounds terrible. Maybe just my mediocre building skills, but I never could get a decent OD sound out of it. It sounds okay clean, but most tube amps do.
Most of the subsequent amps I've built have sounded much better: AX84 P1 & HO, AC15 lite, various Tweed Princeton circuits, and modded Valve Juniors.
Still, it was a good experiment in building an amp.
tung
The article has good information on modding SE amps. There was a lot of thought put into the design.
Having said that, the amp sounds terrible. Maybe just my mediocre building skills, but I never could get a decent OD sound out of it. It sounds okay clean, but most tube amps do.
Most of the subsequent amps I've built have sounded much better: AX84 P1 & HO, AC15 lite, various Tweed Princeton circuits, and modded Valve Juniors.
Still, it was a good experiment in building an amp.
tung