J님이 재미있어 할 것 같아서...
Yamamoto 뿌리 CA-03L 사서 부검후 맹긴 것 깉은디.. 로드 저항이 1K 랍니다.
Tube DIY Asylum
Pentode Linestage experience
Posted by sganti (A) on May 13, 2007 at 19:49:18
Hi All
I wanted to share my experience with Pentode Linestages. I recently purchased a Yamamoto CA-03L [phone + linestage]. It was one hell of a preamp. He uses 6AK5 pentodes. Following his principle, I first build a linestage using 717A, very good sounding but not as good as the Yamamoto Linestage [that is my reference point]. I had emailed Shigeki San and asked him if cost was not objective what are his favorite tubes -- his reply was 6AK5 and C3M's. I had never heard about the C3M tubes, did some research and found there are C3M's, C3G's and C3O's. Got myself a bunch of C3M's and C3G's. C3M requires a 20V filament supply, so I went with building a linestage using C3G which uses 6.3 Volts. BTW, I am using these tubes as Pentodes and not triode connected..
I just finished it and fired it up, and I was amazed!! I have never built anything sound so good, it was in par with CA-03L if not a little better on liveliness. The music dynamics/transients are unreal, if I listen to Beethoven 6th Walter Bruno, the storm is amazing, I have never heard some many instruments so clearly delineated during the cresendo's. I am trying all kinds of music old rock recordings, jazz, classical etc. etc. it just seem to get better and better..
Shigeki San is an amazing builder, he is like the Zen master for building audio equipment. I am glad I got his stuff, it just made me realize how crappy all the stuff I built before sounded [811A amp, 76 line stage, etc. etc]
I have question for folks in this group -- does anybody know a source for Renesas/Hitachi HZ**L Zeners. These are Silicon Epitaxial Planar Zener Diode for Low Noise Application, and don't need a bypass capacitor for nose. I have been trying to get my hands on these but no success so far..
ciao
ganti
---
Here are the operating point details:
V_plate = 190V
R_plate = 1K
I_plate = 7ma
V_grid2 = 90V
I_grid2 = 2mA
V_cathode = 1.2V
I think the transconductance at this point is around 7000microMhos, so I am getting a gain of around 7
quickly.
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어너마는 더 낮은 560R 을 쓰니 더좋다카네요
Re: Am I missing something?? - mach1 21:49:42 05/14/07 (0)
In Reply to: Am I missing something?? posted by mikeyb on May 14, 2007 at 10:47:44:
I have used plate loads of 560R on a high transconductance pentode linestage. It's best to use the lowest resistance that gives you your required voltage swing - going from an already low 1k to 560R gave a sonic improvement.
Their main foible is the need for a very low ripple plate supply and a regulated g2 supply - PSRR is very poor.
pm
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