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HiFi (Chifi) tube amp build - but my own design.
#34

I got things pretty much in place, double checked, waited a couple days, did some resistance checks and powered up through a variac and dim bulb. B+ seemed pretty close to what I wanted so I brought it up enough to get something. Yup, I could get a signal if I touched the input, so I plugged in a CD player and ... AND.../// it sounded .... AWFUL! Almost no volume and was badly distorted. Did a few voltage checks and plate voltage was really high on the inverter. I could hit either side of the coupling caps with a signal and it sounded clean, hit the grid of the inverter and - nothing. It was dead. Tried another tube, same. The inverter was dead. So I studied the diagram (that I drew), everything looked ok, that is, until I rechecked the driver tube diagram. OooOooohhhh - wrong! I had the triode grid and cathode pins reversed. Well, that'd do it. I have a feeling I just looked at the wrong pinout and drew it wrong. 

So I switched it tonight and brought it back up - and ... AND ... SQUEEEEAAAALLLLL SQUEAL SQUEAL! Well, shucks. Been there, so I flipped the ground and feedback and it came on quite well. So, yeah, oops! So anyway, some of the same stuff I ran into before. I don't know if flipping the plate leads would change it or if the tranny is backwards. Anyway, I haven't really done a thorough sound check, but I did note it has the same lousy 60 cycle hum as my last kit. Not bad, just kinda ... there. So I know it isn't a filtering issue. Gotta either be coming the heater or ground loop. Since this is an experiment, I'm going to try a few things. I set this up so I can isolate the ground with a bus I may try some different heater arrangements, like DC, or maybe a hum balance. But all in all, the fact that it works is an accomplishment!  And, no smoke! Icon_thumbup

   

If I could find the place called "Somewhere", I could find "Anything" Icon_confused

Tim

Jesus cried out and said, "Whoever believes in me , believes not in me but in him who sent me" John 12:44


Messages In This Thread
462ron - by 462ron - 10-15-2024, 09:07 AM
RE: HiFi (Chifi) tube amp build - but my own design. - by TV MAN - 11-20-2024, 01:17 AM



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