K31-11 Russian silver mica

[Conrad Hoffman]

Hi Rdf, certainly true of most ceramics, but a modern multi-layer NPO can be remarkably good. DF will be close to unmeasurable, and DA is good as well. Obviously, since it's an NPO, the tempco is near zero as well. I have a friend who was making standards out of these things, and researched them quite thoroughly. They aren't as good as an air cap made with invar plates, but they come surprisingly close. The downside, like all NPOs, is that the maximum values are limited. Caveat- I don't know if the above is true for every NPO ever made, or just the modern multilayers.

[rdf]

You're right, I had completely forgotten Bob Pease's examination of the issue (http://www.national.com/rap/Applicat...570,28,00.html).

[alboran]

hi to everybody
I would be very happy, if you point out to me some condensers to use in my net riaa.
me which capacitors I have to look for? with which dielectric? what type?
I want to improve the sonorous qualities of my phono.
you have made a lot of experiences and a lot of tests, and also studied a lot the matter capacitors, therefore it is easy to say what the best capacitors is for riaa.
I look for values of 4700pf and 27000pf.
thanks for the help

[Conrad Hoffman]

Have a look at Panasonic parts ECQ-P1H472FZW and ECQ-P1H273FZW. Inexpensive and perform well. 50V. There are much more expensive "boutique" parts, but I'll leave it to other to suggest what might be best in that department.

[Salas]

Originally posted by fred76
Hello,

Any of you guys tried these surplus Russian silver mica (K31-11)?



Here's my experience with micas... I used some CDE micas in RIAA, two different phono designs both tube. The first design is with 12AX7's with no name polys and replaced them with CDE's, resolution went up notches and music sound more natural/relaxed but still relatively neutral. The other design uses high gm tubes and sounded too upfront with a bit of edge in the sound when I tried to replace some polyprops with CDE's (magnetic)... Some say it's the magnetic materials that makes them bright, but I've heard the pricey ACL micas that are magnetic but they don't sound metallic.

FWIW, the seller claims that the Rusian micas pic'd above are not magnetic.

Thanks.

They aren't magnetic, I have just tried to stick em on a woofer's magnet and they fall like a stone. Their sound is exactly as you describe. Interestingly your sonic description applies where I use them too. As 10kHz square wave, anti ringing feedback loop caps in triode push pull power amps.

[fred76]

Originally posted by salas


Their sound is exactly as you describe. Interestingly your sonic description applies where I use them too. As 10kHz square wave, anti ringing feedback loop caps in triode push pull power amps.

Hi salas,

What do you mean by my sonic description? The too upfront and edgy sound in a phono design using high gm triodes, or the natural sounding part with 12AX7's?

Wow, somehow I missed your post on this old thread...

Thank you for the non-magnetic leads info.

fred

[Salas]

''resolution went up notches and music sound more natural/relaxed but still relatively neutral''

That is what I got by using the Russian non magnetic silver mica types, that are shown in my little pic above.

[fred76]

Ahh, thank you salas...

That was very helpful info.

Best,
fred

[oshifis]

I use those Russian SGM3 silver mica capacitors in my RIAA network, in combination with Vishay audio resistors, as I described here:

Vishay Audio Resistors

I opened (broke) one SGM capacitor. The case is ceramic, the leads are tinned copper. Tolerance is 0.3% and 0.5%. The seller said they are vacuum sealed. They are not filled with oil inside, there is just some oily substance that sticks the mica layers together.

They sound beautifully

[Salas]

Originally posted by oshifis
I use those Russian SGM3 silver mica capacitors in my RIAA network, in combination with Vishay audio resistors, as I described here:

Vishay Audio Resistors

I opened (broke) one SGM capacitor. The case is ceramic, the leads are tinned copper. Tolerance is 0.3% and 0.5%. The seller said they are vacuum sealed. They are not filled with oil inside, there is just some oily substance that sticks the mica layers together.

They sound beautifully

Ssshhh! Keep your voice low... Objectivists around the corner!