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2L man your input is appreciated . I am changing this circuit from SS rectification back to tube rectification . I have been messing with the power supply rail , subbing in "sag" resistors to bring down my HT and came to the conclusion that a 5u4 would probably be the best solution . Your advice...

Filament voltages are good and right on at 6.3vac . The PT I'm using had a 5 volt winding that I used as a bucking transformer to bring my voltages down . I thought I was good with my numbers and wanted some confirmation . Still trying to figure this stuff out . Thanks mountainhick !

Please ... Built from my stash of stuff , organ trannies so voltages are a little high . Plate voltage for each tube is 457/455 vdc Plate current is .047/.050 ma Plate dissipation is 21.48/22.75 w . I built this with an adjustable bias supply and it is set to -44.7 This works out to 72/76...

The 6v6 is used as a voltage regulator maybe . I saw something like this on an old Allen Organ sitting in a thrift store once . There was only one tube in the entire organ so I let it stay at the thrift store .

FenderLover I had one like that and the two SE outputs were 7868 tubes . The single ended OTs were rather beefy for consumer parts . I still have them in my pile somewhere .

I built this stereo from this schematic with some changes and listen to it daily . Dead quiet at full volume no signal .

Sounds like a Motorola not a Magnavox . Are the SE outputs 7868 tubes ? I once received a Dynaco stereo amp that was used as an amplifier for a Schober organ in a church . I can't offer much so don't let my moniker fool you . I like HiFi stuff , a lot . I am terrible at the math and theory...

Using Rob Robinette's bias calculator I come up with 10.3 watts PD . 73.6% of max 14 watts . 6v6gt plate to cathode voltage is 284vdc . Voltage at pin 8 is 19.2vdc . 500 ohm cathode resistor . Where could/should an amplifier like this be biased ? I thought I needed to be closer to 100% .

Some progress . I should have described the tone as ragged maybe . I changed the first dropping resistor to a 5k resistor . That helped clear up the raggedness immensely and brought my screen voltage down under the plate voltage by about 10 volts . I removed the bypass cap from the second...

Sad ... I saw YES twice in the 80's at the Hollywood Sportatorium in South Florida . 90125 and Big Generator albums. They were fantastic! I was probably 18 or so .

Thanks for the suggestions . I will start with the power supply dropping resistor first and then the K resistor on the 6v6 will probably be the second change . I wont be able to start these changes until the weekend . I scored a variac at the thrift store yesterday and have been working on that...

It's a junk box Princeton , maybe . I punched the numbers into RobRobs bias calculator and it seems to be about 93% of PD . If I am using the calculator correctly . Also the plate voltage is lower than the screen voltage . May be because of my power rail . Do I need to drop some more voltage...

Just built this amp and would like some input please . It is a single ended 6v6gt output with 12ax7 pre and SS rectification . As it sits the tone is a little ratty sounding , harsh . Kind of a princeton amp but with different cap and resistor values . I used what was in arms reach and junk...

Thanks for your help TDPRI ! I'll start another thread on this amp .

All wired up now . Seems to be working well . PT not getting hot or emitting foul smells . Bonus , I have sound that is pretty good so far with my limited testing . I haven't wired in the 6v6 cathode resistor yet . I'm using jumper cables to switch in different values . I'd like to get some...

Thanks again to all here on the TDPRI site for your help . Have to go to work now but tomorrow should have the filament circuit wired and will be ready to start it up . I'll let you all know how that goes .

Andy , this was a question I was going to ask to make sure I am implementing the rectifier correctly . I have already converted the rectifier to a half wave using two diodes ,I think .After reinstalling the PT , I removed the virtual center tap by clipping out the two diodes connected to ground...

Printer , your statement is the question I was attempting to ask . I would reinstall the PT now but I am afraid it might be damaged . Stinky it is . Smells like dead transformer but tests well on the bench , no load. Still good ?

Sorry , voltage measured across both legs is 500 vac . Each leg puts out 250 vac . It is a smallish transformer that I'm pretty sure came from a webcor product . I actually have two and just tested the other one and it behaves in a similar way . Also I found a schematic on this site from a...

I have a PT from some old gear that I parted out . Total of 6 leads . Two for primary , two for secondary HT @ 500 vac and two for secondary filament @ 6.3vac . No center taps . Had it wired into a single ended circuit with a SS bridge rectifier and it got hot immediately so I shut it down ...

Digging around on the internet I found the reel to reel that I pulled this transformer from . It is a Voice of Music model 711 . The schematic shows the green to ground the yellow to the speakers and the black to the cathode of the 6v6 . Schematic shows 300vdc on the plate of the 6v6 . Anyone...

Is there a way to test the OT in circuit ?

I'm sure that the OT is for single ended . It was installed in an amp that I built and gifted to my nephew . I recently traded him for a different amp that I just finished . This SE amp sounded really good and I'm trying to find out why by reverse engineering it in order to build another amp ...

2L man , I have continuity between all combinations of secondary wires . The combinations of black and yellow measure the same as green and yellow in ohms . Black and green measure about twice as much as the other two pairs in ohms . For testing purposes can I combine any leads to achieve a more...

volts in-----volts out-----WR---------IR----------Spkr Imp. in ohms 4.9-----114.8--------23.43------548.97-----15.48----------------black and yellow 5.1-----59.2----------11.61------134.79-----63.06----------------black and green...