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PostPosted: September 23rd, 2018, 6:04 pm 
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http://bristolwatch.com/ccs/LM317.htm

Roscoe


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PostPosted: September 24th, 2018, 10:37 am 
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Location: Baltimore MD
I went through the tutorial and a couple of videos. I am getting a feel on how this works. I am just wondering what the importance CCS for filaments are.
I think PS fluctuations usually happen pretty quickly. Filaments being heated probably do not fluctuate as fast as the PS does and keeps pretty even in what they do. I think.

The filament PS just needs to be beefier than the need.
Don't these voltage/transistors add noise to the system, why not keep as sinple as possible?


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PostPosted: September 24th, 2018, 11:10 am 
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Because with AC filaments, hum increases as filament voltage increases. AC 845s on horns just doesn't work.... I've not heard any noise in my 845 amps that I can attribute to the CCS on the filaments, and they turn on nice and slow which is good for tube life.

Roscoe


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PostPosted: September 24th, 2018, 11:41 am 
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You might want to check with David Berning as to the effects of DC on filament life. He uses HF AC that will not diminish tube life and eliminates hum.


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PostPosted: September 24th, 2018, 12:06 pm 
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I understand about AC filaments and the possibility of hum, even though I am using AC filament in my 6EW7 preamp and its as quite as can be. This was a Gary Dews (Border Patrol) design and I like the sound very much.
I just want to understand CCS more. I just do not understand the need for it with filaments.

I that DB's stuff is well engineered and highly acclaimed but for now I want to stay away from complexity.


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PostPosted: September 24th, 2018, 12:46 pm 
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6EW7s have heaters, not filaments, makes it a lot easier to get things quiet. Using DC is a compromise, but sometimes you have to live with it. In my experience for filaments if you;re going to go DC, CCS is the best compromise.

Roscoe


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PostPosted: September 24th, 2018, 1:48 pm 
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Grover - besides hum differences, did you notice any sonic changes? I seem to prefer AC over simple DC because it sounds better (more vibrant, colorful).

Not sure what speakers you are going to be using for this amp but if they are anything like your old ProAcs, you should be able to use AC on 300Bs and get virtually no hum out of your speakers. My speakers are 100db efficient and they are pretty quiet with AC, less than 10mv at outputs and I have not done anything heroic to quiet them down.


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PostPosted: October 9th, 2018, 10:37 pm 
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TubeDriver wrote:
Grover - besides hum differences, did you notice any sonic changes? I seem to prefer AC over simple DC because it sounds better (more vibrant, colorful).

Not sure what speakers you are going to be using for this amp but if they are anything like your old ProAcs, you should be able to use AC on 300Bs and get virtually no hum out of your speakers. My speakers are 100db efficient and they are pretty quiet with AC, less than 10mv at outputs and I have not done anything heroic to quiet them down.


I'm not getting notifications so I changed the ptions in my profile. Thanks, Pete, yes, AC sounds better. :-)


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