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Quanghao Audio Design Quanghao Audio Design is a producer of DIY Audiophile Kits and PCB boards, selected from many listening tests!

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Old 17th September 2010, 10:30 AM   #11
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What about 6N1P?
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Old 17th September 2010, 10:48 AM   #12
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Quote:
Originally Posted by Wavebourn View Post
What about 6N1P?
I not test it, but
6n1p, or 6h1, you can you use for this circuit Anod at 90-100!
Some friend have been use it!
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Old 17th September 2010, 11:48 AM   #13
SY is offline SY  United States
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What's going on in the cathode circuit? Are you switching between bypassed resistor and a non-bypassed CCS?

Have you completed the wiring since those pictures were taken and actually tried the unit out?
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Old 17th September 2010, 12:57 PM   #14
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Quote:
Originally Posted by SY View Post
What's going on in the cathode circuit? Are you switching between bypassed resistor and a non-bypassed CCS?

Have you completed the wiring since those pictures were taken and actually tried the unit out?
Yes!
That is one option,
If you need Lower Z Out put, Use CCS
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Old 17th September 2010, 01:32 PM   #15
SY is offline SY  United States
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How do you manage lower output Z with a CCS in the cathode?
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Old 18th September 2010, 08:22 AM   #16
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Quote:
Originally Posted by SY View Post
How do you manage lower output Z with a CCS in the cathode?
Oh! I'm sorry, I'm wrong, CCs as it not down Z out!
Thanks!
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Old 22nd September 2010, 03:28 PM   #17
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This is some PCB, please it! thanks
Attached Images
File Type: jpg Board-Pre818-a.jpg (206.8 KB, 818 views)
File Type: jpg Board-Pre818-B.jpg (182.2 KB, 798 views)
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Old 22nd September 2010, 03:33 PM   #18
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Quote:
Originally Posted by Wavebourn View Post
What about 6N1P?
Hi Wavebourn!
I see you successful about the Pre with tube 6h1, Can you show me please?
I wan test with your advance

Thanks
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Old 22nd September 2010, 05:10 PM   #19
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Quote:
Originally Posted by SY View Post
What's going on in the cathode circuit? Are you switching between bypassed resistor and a non-bypassed CCS?

Have you completed the wiring since those pictures were taken and actually tried the unit out?
Hi SY,
This is a well known design in Vietnam that apparently a lot of people have built. (I have an audiophile buddy who lives there, so I follow this stuff to some extent.)

Quangho
Were it me I would put a large capacitor across the CCS, were it really me I would use fixed bias (batteries?).. I would expect the CCS to significantly increase rp (source impedance) and reduce gain, and the LM317 makes a pretty mediocre CCS outside of power output stages, although the fairly high currents probable help here. (Look at some of the very nice CCS designs lurking here.)
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Old 23rd September 2010, 04:22 AM   #20
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Hi kevinkr!

Well thank you!
Well yes, the LM317 can not be the best, I used Jfet replace it! I recently tested the following schematic, and I enjoyed it! 6h30pi particular tube,
Thank you and hope you add comments to this pre!

With tube 6h30 i like:
Anode = 90V, 40mA/ Tube
6h6 I like:
Anode = 170V, 40ma/Tube
This is other circuit, Please see it!
Thanks
Quanghao
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File Type: jpg PRE-818B.jpg (145.6 KB, 799 views)
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