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Old 1st May 2011, 09:46 PM   #151
Salas is offline Salas  Greece
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The Russian Mica is good in that position, but the value is very deterministic also. Will depend on the rest of your system tonality as well. How did you arrange the heaters PSUs?
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Old 1st May 2011, 10:14 PM   #152
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2 x regulated supplies, one reg for the upper 6N8 + 6N2 wired in series, same for the lower.


I had plenty of spare 15VAC transformers to use... so went for the heaters in series.

*****************************************
2 separate listening rooms. One with stacked quads, 6SN7 aikido, ST70 running KT66s. Replinthed lenco L75 with roksan tabriz arm, benz L2 cart. Currently using DIY Ono for phono duty. Sound is big and bold and great for rock.
Second room, teres 260 TT with terminator style air bearing arm. DCB1 + (currently) tubecad EL84 triode PP amp and sachiko horns with fe206. Using pearl phonostage + lundahl step-ups and Zyx R50 cart. Sound more refined and polite but no less engaging.


Fran
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Old 1st May 2011, 10:20 PM   #153
Salas is offline Salas  Greece
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Don't know about series heaters, wasn't tested that way. Still those two tube types draw about same currents, hope they will share well. You lifted the upper bootstrap CCS valves of the mu follower totem as prescribed? Nice collection of listening stuff, especially the stacked Quads, you will have good discrimination of tone so to tune up parts, Riaa values, etc.
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Old 1st May 2011, 11:05 PM   #154
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Sure, I know its a risk. I have read (only once) where someone said it didn't suit 6SN7 types - but broskie says no problem, plus I have used it in the aikido with no noise issues. We will see soon enough....

Heaters for upper pair will sit about 80V off gnd. Actual circuit is exactly as per itch rev1, heater supplies - exactly as per, except I don't have cap on the output of the regs yet (only 1.0uF PP), HV shunt is done as mentioned previously.

Couldn't find decent coupling caps in parts box...... grrr. Only things I have are panasonic (http://panasonic.com/industrial/incl...BD0000CE47.pdf). I think I will fit them and I can then at least see if the circuit works OK. When the other caps arrive, I can swap them in easily. will be nice to see the difference too.

Fran
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Old 1st May 2011, 11:37 PM   #155
RCruz is offline RCruz  Switzerland
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Quote:
Originally Posted by woodturner-fran View Post
I have most of the circuit wiring done now, I'm waiting on the K42Y coupling caps to arrive. I do have some other GE 0.68uF caps here that I know sound pretty good, so I might push them into service.

The RIAA caps are some nice matched mica/k42Y types from Russia via some Greek generosity (the mica measured 15.5nF, so a shade high). The output caps are some MKP types I had from a long time ago.

The pic is probably the worst quality one ever (phone camera) but give the idea at least.


Click the image to open in full size.


Fran
Hi Fran

I am looking forward to hear your first impressions using the 15.5n micas.
i have been using 15.72n in that place and they really sound good... I could not find lower values yet.

Like your work... what type of wire are you using ?

Ricardo
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Old 1st May 2011, 11:52 PM   #156
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SPC in teflon from navships on ebay.... eBay Shop - John's Silver Teflon Wire Shop: 26 AWG, 22 AWG, 24 AWG

George had marked the silver micas as 15.743, but when I measure them with my own meter they were 15.5. I suppose that is within the error range of my meter (not a fancy one).


Cascais: it is where I will be going on holidays this year!
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Old 2nd May 2011, 12:09 AM   #157
Salas is offline Salas  Greece
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Quote:
Originally Posted by woodturner-fran View Post
Heaters for upper pair will sit about 80V off gnd. Actual circuit is exactly as per itch rev1, heater supplies - exactly as per, except I don't have cap on the output of the regs yet (only 1.0uF PP), HV shunt is done as mentioned previously.

Fran
The schematic Rev1 asks 1/2B+. So you need to divide near to 150V heater lift. The upper cathodes are at around 200V elevation. 80V isn't enough to bring the heaters in less than 100V distance to cathodes as the tubes spec asks.
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Old 2nd May 2011, 05:57 AM   #158
vgeorge is offline vgeorge  Greece
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Fran,

nice to see your progress!
Regarding the mica caps, I think that my LCR meter is more accurate, as I have cross checked it a couple of times. This is the one I use: TONGHUI DIGITAL HANDHELD LCR/LCZ/LCRZ METER,TH2821B,1K | eBay
Also the RIAA cap values you have now will let you experiment with values a bit, but when you find what you like, best is to replace with Teflon or good MKP's. Of course Ricardo and Merlin are the experts on this area!

George
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Old 2nd May 2011, 09:45 AM   #159
RCruz is offline RCruz  Switzerland
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Quote:
Originally Posted by woodturner-fran View Post
SPC in teflon from navships on ebay.... eBay Shop - John's Silver Teflon Wire Shop: 26 AWG, 22 AWG, 24 AWG

George had marked the silver micas as 15.743, but when I measure them with my own meter they were 15.5. I suppose that is within the error range of my meter (not a fancy one).


Cascais: it is where I will be going on holidays this year!
Maybe your meter is not very acurate (These caps are also market 0.3%).

I just bought some 12.1nF CCT-1 and these are 0.5%... I will report after I try those. (I will trim them until 15.33n)

Thank you for the link.

When are you arriving to Cascais ? Maybe we could meet

Ricardo
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Old 2nd May 2011, 11:18 AM   #160
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Teflon film & aluminium foil 0.015uF 200V 1% 200V TexCap 43 or 400V 5% both 15$00 USD each, you can ask matched pairs to Mark.

Web: Surplus USA Film Capacitors Teflon Polycarbonate Polyester Polypropylene
E-mail: marko@33audio.com
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