Push-Pull A2 6A3/300B
This amp has great specs, produces twice the power from your favorite tube and is simple to build. But you will need to decide which power transformer to use, both have identical performance but one runs cooler than the other because of the laminations. Then select which output transformer you’d like, our standard copper wound or the new PSSS which gives silver performance at a fraction of solid silver price. Read Jack’s comments at www.electra-print.com->Tech Blog->Spring 2007->Class A2 Operation for a description of this new transformer. You can find a list of the Electra Print transformers needed to build this amp below the schematics.
- 50 watts output
- .15% THD
- -1db 15hZ 40 kHz
- .7v to full output
Constructor Note: Capacitor 470uf/450v connected from the center tap of the output transformer must be changed to a higher value than illustrated in the schematic. Issue being that there is a 650v inrush at turn-on. To take this voltage, I suggest substituting the single electrolytic capacitor with a pair in series, along with bypass resistors, as done in the filter power supply. This will give the security of a 900v rating. If an oil capacitor is used, the inrush voltage will not be an issue. Following turn-on, the voltage on this capacitor runs at about 425v during normal operation.
|PPA2 Power M19 lamination||$225.50||Standard Laminations|
|PPA2 Power M6 lamination||$181.50||Cool operation|
|PPA2 Output||$269.50||Standard copper|
|PPA2 Output PSSS||$565.50||Partial Silver Stranded Secondary|
|A2LD-7 Interstage||$104.50||Constant load driver|
|High Voltage Choke||$37.50|
|Filament Choke 3A||$26.50||Note: new value|
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