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In Reply to: RE: EML solid Plate 45 vs. EML mesh Plate 45 .........better for SET ? posted by banpuku on November 07, 2016 at 11:14:54
"My real desire regarding the V4 tubes is to get rid of the filament's cathode resistor and cathode bypass cap"A V4 tube (octal base) is no more able to do this than an UX-4 based tube. In cathode-biased ac-heated circuit terms, the V4 has a centre-tapped filament, whereas with a UX-4 based tube you need need to derive the centre-tap either using resistors (and perhaps a hum pot) or by using a centre-tapped filament transformer. Using a V4 tube allows you to dispense with the two centre-tapping resistors, NOT the cathode resistor and bypass cap
Just curious, what cathode resistors and capacitors are you using? If you would like to dispense with them, filament or active bias are your options; however, probably best to leave either of those alone until you well understand how to implement them.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Edits: 11/09/16Follow Ups:
91, Thanks for the input and education. I am currently using a Mills wirewound resistor and a ClarityCap TC. When the cap is removed, things really sound better, except for lack of low end control and lack of dynamic punch. But the mids and the highs are the best I have heard.
I have tried Filament bias, but the output level goes down considerably and once again, lack of low end control and dynamics. I am not familiar with active bias. Please tell me, why does the output level go down when the bypass cap is removed?
Hi Pat,
Not sure why filament bias would do this - I have not looked into it.
Removing the cathode R bypass cap allows cathode-current feedback, which decreases gain, increases plate impedance... and decreases distortion. Some of the improvement you are hearing could be due to the reduced distortion.
A different capacitor could help (via a different mechanism) tune the sound to your liking. I have noticed differences between Mundorf's M-Cap and Evo Oil capacitors of the same value. My girlfriend noticed it too without being aware I had made the change to the system. Mundorf capacitors are not for me, me thinks. I will be using a Clarity MR in the cathode of my next build.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
FYI regarding caps. I have tried a few, not Mundorf. Here is what I hear.
1. Clarity MR is very clean and has a non-natural sheen to the sound. Plastic-like for lack of better words.
2. Russian k40 is very natural and tonally colorful. Not as solid in the bass as the very best, but still very good in the bass. I really like the tone of this cap and use it in several places.
3. Jupiter Copper Foil Oil - very very neutral and natural. No tonal anomalies anywhere. It is a bit dry and certainly not as colorful as the Russian, but it also has no extra techni-color. I suspect it is as neutral as possible.
4. Duelund Cast PIO - I just put these into my amp recently. Only about 50 hours on them. Hard to say how much they differ from the Jupiter's. I think they are similar, but the Duelunds might have a bit more texture and color. TBD.
Hope this helps in your decision. FYI: I have some Russian, Clarity MR and Jupiter caps for sale (used). Just in case you want to try something for 50% off. Just offering.
Thanks for the info - could be helpful!
I don't know if cap "sound" is the same in each location, that is, does a cap sound the same in screen bypass as cathode bypass as coupling? I suspect not, but your feedback will be added to my notes.
The M-Cap was kind of dull but grainy; the Evo Oil is more "dramatic", but highlighted from the upper mids up, which seems to be typically Mundorf.
I have thought about Rike's new S-Cap 2 (not sure about Alu as a conductor tho) or if I win the lottery, multiple Audyn Copper Max... ouch. I need > 20uF and ~400V - not easy.
Thanks,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
I have tried Riken as well. Similar to claritycap with very little coloration. Good dynamics.
I too am looking for 70 to 100uF and so, if you have any ideas please let me know.
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