• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

My 6S19P Linestage


2006-05-04 9:15 pm
Haven't sketched out the schematic but it's pretty simple. One 6S19P per channel in GC. 3K+4.7K in parallel to bias at -40-45V ~22mA or so. Bypassed by a 150uF 63V 105 degree 'lytic, and a .22uF 630V film. 63V is a bit close but the grids shouldn't swing that much since they're being fed by a CD player.

Anode load is a 6K 10W resistor. Output RC is 4.7uF Solen (peeled and painted with heat-resistant enamel after too many soldering iron scars) and 470K. Volume control is an Alps Blue Velvet.

PSU: Two 6.3V 6A transformers back to back, one of the CT's grounded. Voltage doubler with 2 UF4007's, 2 450V 100uF caps, with 220K in series to balance voltage. 10H 65mA choke into 220uF, then 500 ohms and 100uF, and a channel split with 350 ohms/47uF each.

The preamp is dead quiet (after I realized I had to connect chassis ground to mains ground to kill huge hum), aside from the microphonic 6S19P's. Does anyone thing the -EV type would be worth it?


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