The Amp Garage

Omar and all interested,

I still have gut shot pictures of the komet amp. Some were not released in the first set. If we have space or anyone else does we can put them up. Just let me know if interested.

Eric

Thought I would throw a couple pics up of the amp in this thread. Also got some voltage readings with the amp biased at 40ma. They seem a tad low what do you guys think? B+1= 385 B+2= 368 B+3= 298 B+4= 280 B+5= 264 B- = -29.64 I also took a quick reading with out the power tubes and B+1 was 410. Eri...

Update: :D I did the bias mod suggested by Matt and it worked great (thanks so much). I was able to get a range of -42 to -22 volts. I also reversed the phase on the OT and that took care of the feedback squeal. My very early impression of the amp is, it's loud and quite bright but it has a nice cla...

Matt,

Sorry I didn't see your question in your last post. Yes I'm using a THD hot plate in the 8 ohm load mode. That way I don't have to hear all the feedback.

Eric

Thanks Matt...I will try the bias mod and report back.

Eric

Matt,

Thanks for the info. I too calculated too little bias voltage using this circuit. Surely I'm not the first to get bitten by this...anyone else had this problem? I just hope I haven't fried anything. Also I may have the dreaded positive feedback problem.

Eric

Hey Jackie,

Would a positive feedback loop cause my bias voltage woes? I hope the answer is yes.

Eric

Hi Chris,

I looked at the bias caps and they are hooked up as follows...positive lead to ground and negative lead to bias circuit path. Is there anything I'm missing on the schematic? (like special grounding requirements for the bias circuit)

Eric

Hi Everyone, I have been building an A1a wreck for the past couple weeks. I didn't rush and took my time to double check everything along the way. I'm using the transformer set from Heyboer. When I first powered it up, there was a loud lower freq. feeback regardless of the vol setting. I then plugge...

Thanks Matt!

Eric

Hi all, I'm in the process of building my first express using the A1a schematic. The stupid question I have is concerning the EL34 tube wiring. What do you do with the third or unused grid? Lets say the pinout for the grids are pin5=grid 1 (nearest cathode) pin 4=grid 2 pin 1=grid 3 (nearest plate) ...