On Mar 11, 2:27*am, John L Stewart John.L.Stewart.
wrote:
This is something I built in 1968. Finally wrote it up in 2005. Go to-
www.audioXpress.com
& click on the tab Web-exclusive Articles.
There you will find the PDF 'A Tiny Vintage Garage Amp'.
Ya, I know, you could do better!!
Cheers to all, John
--
John L Stewart
Not bad John and its like many guitar practice amps. The 6AQ5 is
harder to find now than EL84 which probably has a mushier over drive
sound than 6AQ6. Maybe consider adding variable NFB. And where's the
reverb tank and speaker?
Golden Tone amps in Oz used to make a guitar amp with a single EL84 in
the 1960s, but no reverb, but with 12" speaker.
Because its PT was more than large enough I was able to change it tp
PP with two 6V6. It had a very primitve and thumpy going tremelo, so I
put in tremolo from Fender with neon and LDR under wrap, much better.
Not much NFB used, THD below clipp don't matter, sounded OK for small
venues or practice. Lat week I repaired another Golden Tone PP with PP
6AQ5. No FB at all. Input was 6AU6 in pentode, high gain, and power
amp driver was 12AX7, one input gain, one concertina inverter. Tone
was controlled by a cap and pot from the first audio gain 12AX7 to
ground. The rising speaker impedance without NFB ensures a bright
sound, and this can be cut with the tone cut control. No need to boost
bass, just cut treble and turn up volume. Not much deep bass anyhow
because the cabinet is small, 6mm plywood. and the back panel has long
been lost.
There were two inputs feeding together for the input 6AU6 so a singer
and piano-accordian could liven up an Italian wedding. Sound quality
was controlled by red wine. But Geloso made a special little baby amp
head for which a speaker in box was needed.
http://www.flickr.com/photos/25988513@N08/2504502894/
I rescued one at a rubbish tip in 1994, moments before a bulldozer ran
over it. I repaired the arcing OPT and rewired it and sold it for $350
to a bloke who had another and they much suited his music classes at
the school where he taught. He's now Dr Zot.
http://www.zot.com.au/vintage..html
Patrick Turner.