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Old 3rd March 2013, 08:46 AM   #2561
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Don't change the power transformer until you have connected the regulator up correctly! The circuit looks fine as it is. You can tune the 440uF capacitor in size, but you won't get anywhere until you connect the whole supply to the combination of 26 + cathode resistor.
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Old 3rd March 2013, 04:18 PM   #2562
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Originally Posted by andyjevans View Post
Don't change the power transformer until you have connected the regulator up correctly! The circuit looks fine as it is. You can tune the 440uF capacitor in size, but you won't get anywhere until you connect the whole supply to the combination of 26 + cathode resistor.
Thank you Andy! I will leave it as is then.


Abe
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Old 11th March 2013, 12:47 PM   #2563
12B4A is offline 12B4A  United States
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I finally finished my flea-powered 26 headphone amplifier. I just had to wait 6 weeks for the Edcor OPTs. Unfortunately those nice looking tube shields I made induce hum . It's a good thing they can be unscrewed easily. It's the exact opposite of my experience with the 26 linestage I built over 10 years ago using Ronan regulators where I had to use shields to reduce hum. Without the shields, it's as quiet as death. I can't hear anything with my efficient Sony 7506s...at least until I play music. With 1Vrms in I get about 3mW out which is louder than my comfort level. The sound character is what you'd expect from a 26 . Pictured below are the test circuit and the final build. Would you believe the test circuit was also quiet as death?
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File Type: jpg 26 Headphone inside.jpg (288.9 KB, 342 views)
File Type: jpg 26 Headphone test build.jpg (311.8 KB, 336 views)
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Old 11th March 2013, 03:45 PM   #2564
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Hi!

Nice job! Neatly arranged interior!

Thomas
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Old 11th March 2013, 03:55 PM   #2565
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I finally finished my flea-powered 26 headphone amplifier.
Could you tell us what pcb's you used? I noticed the K&K CCS board and Rod Coleman's regs. But the other one I'm curious about. Is that the K&K version of Salas's shunt reg?

Last edited by Bas Horneman; 11th March 2013 at 04:02 PM.
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Old 11th March 2013, 05:21 PM   #2566
12B4A is offline 12B4A  United States
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Originally Posted by Bas Horneman View Post
Could you tell us what pcb's you used? I noticed the K&K CCS board and Rod Coleman's regs. But the other one I'm curious about. Is that the K&K version of Salas's shunt reg?
That's tomchr's (Neurochrome audio) version of a Maida regulator on the lower left. I enjoyed doing the surface mount assembly work...a little.

Thanks Thomas!

Edit: The tube shields work after all. I had just forgotten to tie my circuit ground to chassis with a resistor.
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Old 11th March 2013, 06:08 PM   #2567
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I dunno - 26 preamps as quiet as the grave, laid out like Swiss watches, makes you want to commit Hara Kiri....
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Old 11th March 2013, 07:40 PM   #2568
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Quote:
Originally Posted by 12B4A View Post
I finally finished my flea-powered 26 headphone amplifier. I just had to wait 6 weeks for the Edcor OPTs. Unfortunately those nice looking tube shields I made induce hum . It's a good thing they can be unscrewed easily. It's the exact opposite of my experience with the 26 linestage I built over 10 years ago using Ronan regulators where I had to use shields to reduce hum. Without the shields, it's as quiet as death. I can't hear anything with my efficient Sony 7506s...at least until I play music. With 1Vrms in I get about 3mW out which is louder than my comfort level. The sound character is what you'd expect from a 26 . Pictured below are the test circuit and the final build. Would you believe the test circuit was also quiet as death?
Very Nice, congratulations!
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Old 11th March 2013, 07:43 PM   #2569
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Quote:
Originally Posted by 12B4A View Post
I finally finished my flea-powered 26 headphone amplifier. I just had to wait 6 weeks for the Edcor OPTs. Unfortunately those nice looking tube shields I made induce hum . It's a good thing they can be unscrewed easily. It's the exact opposite of my experience with the 26 linestage I built over 10 years ago using Ronan regulators where I had to use shields to reduce hum. Without the shields, it's as quiet as death. I can't hear anything with my efficient Sony 7506s...at least until I play music. With 1Vrms in I get about 3mW out which is louder than my comfort level. The sound character is what you'd expect from a 26 . Pictured below are the test circuit and the final build. Would you believe the test circuit was also quiet as death?
Very nice and clean construction! So, all is in one box and is quiet?!?
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Old 12th March 2013, 02:08 PM   #2570
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Very nice and clean construction! So, all is in one box and is quiet?!?
Yep, two tubes, one box. I think all these wonderful modules that are available (Rod's filament boards, Tomchr's regulator, K&K CCS boards, Salas, Tentlabs, etc.) have made it so much easier to get great performance without resorting to ponderous construction projects.
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