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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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 Post subject: Re: Building a 300b
PostPosted: 10 Aug 2017, 20:35 
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Joined: 29 Apr 2017, 15:14
Posts: 43
the 5 volt connected to the rectifier tube, is the point of b+ for powering the amplifier, perhaps it might be a good idea to remove the ground, off the 5v
centre tap, then the fuse will not blow.. it might help if you locate a book of some sort, to help you understand power supplies, the author of these books really
don't care how much you read about what they have to say, but the guys on this site, care about your not making sense rational. there is a hole in the bucket.


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 Post subject: Re: Building a 300b
PostPosted: 18 Aug 2017, 19:14 
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Joined: 24 Sep 2012, 22:42
Posts: 14
I enjoy listening to this amp.
I changed the rectifier to 5U4G and it decreased the voltage by about 25 volts.
I have a few observations:
1. Hum level is dependent on the 6SN7. I have 4 Sovteks and 2 JJ's, I can get <2mv on 2 of the Sovteks, the rest varies from 2.2 to 4.5mv. The hum follows the tube.
2. I have to adjust the 300B hum pot every time I change the 6SN7. I thought the pot is only for the power tube.


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 Post subject: Re: Building a 300b
PostPosted: 18 Aug 2017, 20:28 
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Joined: 06 Apr 2009, 10:08
Posts: 1466
Location: US Pacific Northwest
Can you post your final schematic?

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Matt
It's all about the Glass!
http://www.CascadeTubes.com
Cascade Tubes Blog


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 Post subject: Re: Building a 300b
PostPosted: 18 Aug 2017, 22:25 
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Joined: 24 Sep 2012, 22:42
Posts: 14
Hello Matt,
It's the one from here:
http://diyaudioprojects.com/Schematics/ ... ematic.htm
Only changes are: no bypass cap on the 6sn7 470-ohm resistor and 750-ohm 300B cathode resistor.


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