RE EL34 tubes

[Bob Meyer]

Current price for EL 34's is,$8.60 for china(junk),
Telsla EL84's $13.60 ea,SVETLANA EL 34 is $14.95 ea(BEST!!)
Got a HEATH-KIT stero amp with 4 EL 34 output tubes,
model AA-121
Needs to be re-bult.

I also have a HEATH-KIT Mod.AA100 with 4-7591A output tubes. I did rebuld it.New caps,some resistors and new tubes
7591A tubes are hard to get and costly!!!
no longer made,

I did re wire output tubes for 5881(6L6WGC).
I did not put in 220ohm bias resistor in like in vacumme tube vally mod sayes.
I re did bias so plate current is in range of the tube.
Cathode bias would drop output power some accordding to tube manual and my amp was fixed bias for 7591A tubes.
Fixed bias volts for 5881 were different so I redid bias supply buy using different resistors and zenner diode 5W (2 PC)
to get bias supply where I want it.
I did not notice a change in sound qualty or power difference.
I now have current tubes in the amp.

Bob meyer

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