[longplates]

Hello-- I am curious if anyone has  experience using the Green, metal-body Russian K75-10 variant oilcaps for interstage or output coupling (especially for the 1uf output caps) in a Hagerman Cornet2?  I would love to use NOS Vitamin Q/Hyrel Q 1uf output caps, but the seller that I bought 1 uf/400 VDC Q caps from sent me (6) pieces 2 uf / 400VDC  Vitamin Qs instead of the 1 uf Q caps he promised. Oh well-- I got them virtually free when I pointed out the mixup, and they WILL find a home! ANYway-- the K75-10 Russian oilcaps are unusual in that the dialectric is said to be a "hybrid" of paper and "lavsan"...  lavsan being a trade name for a type of polyester film extruded under very high pressure and tight winding tension  and at higher heat than normal which.... (again, I'm quoting vaque e*ay sellers as sources!!) "is said" to give the resultant PETP film unique properties that are much closer to polystyrene than polyester. Not sure about THAT, but... The Lavsan being coupled with oil-impregnated paper, this SHOULD be a hot capacitor! But I find precious little info. One thing I can say with certainty-- because I see capacitance values all the way up to 12 uf+ for the K75-10 caps, they at least will be applied in DC handling service. They are CHEAP, and for power supplies have to be at least on par with Solens... but again, anyone passing MUSIC through a Russian K75-10 series capacitor? Thanks in advance for your time!

[galyons]

I did for awhile, not in my Cornet2, but in my line stage.  6uF output caps.  Sounded better than the stock Mundorf Supremes =]> smoother more musical presentation, bigger soundstage and more precise imaging .  Replaced the Green Meanies with KBG's and got another another level of improvement, especially timbre. 

Cheers,
Geary

[longplates]

Excellent! Thanks so much for the input. With prices on 1 uf / 500VDC K75-10s running about $5 each WITH shipping included, they sound like a definite "must experiment with"  By the way, The KGB capacitors you speak of,  are these the non-cylindrical-shaped body, or "bathtub" shaped caps? (silver rectangular body, with two terminals mounted on wide top surface)? I can only find silver-color .5 uf /500 VDC in this type, unless I am looking at the wrong type capacitor. I have had, though, great results with the various Russian capacitors... especially in light of their fantastically low cost.  Thank You again for some concrete info on the K75-10 Green caps!

[poty]

If you like I can translate Russian datasheets for the capacitors. I don't have much experience with the capacitors, but mostly they are rated up to 10kHz. It may not say anything, because many soviet era capacitors exceeds expectations, but as far as the rating includes voltage degradation - I'd thorougly count the margins.

[gosha68]

From my personal experience, I would stay clear of any soviet-made components marked  as +/-20%...

And here is kind of lengthy explanation why:

Around 1982 I was working in the quality control department ("OTK") at the factory producing K40s, K72s and similar capacitors, right on the calibration machine. This machine had five outlets: +/- 5%, 10%, 15%, 20% deviation and "damaged goods". Nobody was allowed to touch the first three bins, everything with up to 15% deviation was picked up by an on-site uniformed military representative. Capacitors from the +/-20% bin were bulk packaged and used in industrial applications and whatever was spitted in the "damaged goods" bin was marked +/-20% and used in consumer products and sold in hobby shops. Zero-waste approach the Russian way.

[poty]

I'd not put all parts with certain tolerance in one "bad" bin. I know military electronics rather well and could assure that there were a lot of parts with even worse tolerance in the gear.
I don't know for sure the source of now-selling-parts , but can guess - they are either from military spares (they are very good!) or from modern factories (moderate).

[longplates]

Many thanks to all who replied! I have a good friend who owns a restored General Radio Capacitance Bridge, so he helps me test every Russian K40y and vintage Vitamin Q type capacitor I buy for in-spec tolerance as far as capacitance and also for  DC leakage. Even though I am not especially experienced with DIY, I have quickly learned that I mainly like to use K40ys and other P.I.Os in just one circuit block of a complete tube circuit, with modern film/foil types elsewhere, to get a synergy of the sweet, "tubey" 3-D midrange of the P.I.Os (otherwise known as coloration!) with the superior bandwidth and speed/transparency of the best polypropylene types. At the low price point for these Russian K75-10s that I was originally asking about, I just wanted to try them as a new "flavor" to experience in my "voicing" of tube and loudspeaker crossover circuits.  Thanks so much to those who have a depth of knowledge that is amazing!!

[longplates]

Correction-- that should have read that I am not really at all experienced with REAL DIY/actual circuit construction... and that I am SUPER grateful to all those forum participants (and Jim Hagerman himself of course!) who patiently answer my newbie questions. Until building the Hagerman Cornet2, I did  a bit of component swapping--- swapping capacitor types and resistors, etc in my Eico, Dynaco, Heath and other gear.. pretty basic stuff. Thanks again!

[schubert]

I have used those green grenades in many a project, but never got around to sticking some in any Hagerman gear.  In other applications I use them whenever possible - love 'em.  The phono stage might be a problem though as I've found them to be susceptible to picking up buzzing noises on occasion.

[bardamu]

Hello,
I just ask a question ( in another circle) about how to find the outer foil with this and with other caps. I think because they are rather big they will be more sensitive to '' bad vibes '' in their surroundings.
Did notice that they are becoming a bit hard to find. Wanna use them in a crossover. Did buy 20 4,7 mf and the seller did ran out of stock. He did tell they are becoming hard to get. You better have some stock before they end up in Western shops for big money.
Sincere greetings, Edward

[schubert]

From my personal experience, I would stay clear of any soviet-made components marked  as +/-20%...

And here is kind of lengthy explanation why:

Around 1982 I was working in the quality control department ("OTK") at the factory producing K40s, K72s and similar capacitors, right on the calibration machine. This machine had five outlets: +/- 5%, 10%, 15%, 20% deviation and "damaged goods". Nobody was allowed to touch the first three bins, everything with up to 15% deviation was picked up by an on-site uniformed military representative. Capacitors from the +/-20% bin were bulk packaged and used in industrial applications and whatever was spitted in the "damaged goods" bin was marked +/-20% and used in consumer products and sold in hobby shops. Zero-waste approach the Russian way.

Interesting - the 4.7uF K72s that arrived at my house from the Ukraine the other day were marked +/- 10%, so I guess I have reason to be happy!     Two will go in a Kenwood KM-205 power amp and the other two......