this amp need some work to let im sound better.
firt at all switch from 220VAC to 240VAC in France
or 7V heathers!!!
if nothing connect to input rca big buzzzz, 1MOHM direct to 12AU7 input tube!!!
i put PIO and 24Kohm no more buzzzz
12V heathers are AC , two coils one each channel
3X2.2uF250VMKP the last for heather 35VDC ground ref.
and small caps on input tube directli on sockets
main HV bridge are 400V diodes replaced by RGP 1KV and 01uF1KV
01uF 630V for 90VDC bias
input splitter 12AU7 should be very good, two NOS VALVO
12AX7 do a big job TELEFUNKEN only can do this
JJ out for guitar amp
so for biasing this amp i put two 10ohm on plate wires and protection 3KV diodes between them and ground
each phase get only one trimmer so tubes should be same rank for each one,
need 3+3 selected tubes each channel
doing the best each phase tree same rank tubes to get same value on each 1.5ohm then bias balance for same value on 10ohm plate resistor.
also HV timer relays !!!!
firt at all switch from 220VAC to 240VAC in France
or 7V heathers!!!
if nothing connect to input rca big buzzzz, 1MOHM direct to 12AU7 input tube!!!
i put PIO and 24Kohm no more buzzzz
12V heathers are AC , two coils one each channel
3X2.2uF250VMKP the last for heather 35VDC ground ref.
and small caps on input tube directli on sockets
main HV bridge are 400V diodes replaced by RGP 1KV and 01uF1KV
01uF 630V for 90VDC bias
input splitter 12AU7 should be very good, two NOS VALVO
12AX7 do a big job TELEFUNKEN only can do this
JJ out for guitar amp
so for biasing this amp i put two 10ohm on plate wires and protection 3KV diodes between them and ground
each phase get only one trimmer so tubes should be same rank for each one,
need 3+3 selected tubes each channel
doing the best each phase tree same rank tubes to get same value on each 1.5ohm then bias balance for same value on 10ohm plate resistor.
also HV timer relays !!!!
