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More PIO Caps Installed ( Thanks thebes!)


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A few months ago I read a post by "thebes" from 2013 regarding his experience with Russian military surplus PIO caps in crossover networks. My Crites Type B's came with Sonicraft caps at 2.5uf and 4uf. This was my first experience with these. I like the old Cornell Dubilier WMF polyester film for coupling use in my tube gear and was going to try them in my networks. Nothing wrong with Sonicraft and they measure very low for ESR but I felt need for change. I ended up ordering a small assortment of the PIO'S to try from two sellers, one in Bulgaria and the other Romania. I got some MBGP, MBGO and KBG..N or M. They all test really well and are right on for capacitance and low in ESR. I know my Peak tester isn't the best but it gives me a pretty good idea of where they're at. I tried a couple different variations with some paralleled and settled on a 2uf and .5uf for the HF input in parallel and a 4uf (KBG) for the tweeter. After these settled in I noticed a definite improvement toward a more natural and realistic overall tone with instruments and voice. I try to be neutral when evaluating any changes in components staying between subjective and objective. The caps have higher ESR (max of .31) than the Sonicrafts but something in the materials used and construction process of thes PIO's made a real and audible change to my speakers sound for the better, much better. Now these are Crites type B that I built last year to get close to the Heritage sound that I just couldn't afford. I know the Cornwal IV sound very well and I will say that I'm extremely pleased with these to the point at 58 years old I feel I've finally assembled my end game system.  If you've been on the fence regarding foreign military surplus PIO'S, I would urge you give them a try. My 65.00 investment / experiment is one of the best value changes I've ever made in a sound system. Thank you "thebes" for that post which helped convince me to give them a try!20220401_162042.thumb.jpg.da1e65a7b5b31e1212add7e13bd77f99.jpg20210815_080751.thumb.jpg.55757692fdddc584d92256f5f784407c.jpg

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Posted (edited)

I was impressed with the "ballpark" test results of these caps. Excellent sounding and one hell of a bargain. 20220401_142107.thumb.jpg.09c17e826c14171890c8bc151eefbeb3.jpgof a bargain.

Edited by TubesGlo
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3 minutes ago, carlthess40 said:

I have a stash of those, i have not tried them out yet, thanks for your take on them. I’ll have to give them a try now

You won't be disappointed, performance way above their price!

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7 hours ago, TubesGlo said:

A few months ago I read a post by "thebes" from 2013 regarding his experience with Russian military surplus PIO caps in crossover networks. My Crites Type B's came with Sonicraft caps at 2.5uf and 4uf. This was my first experience with these. I like the old Cornell Dubilier WMF polyester film for coupling use in my tube gear and was going to try them in my networks. Nothing wrong with Sonicraft and they measure very low for ESR but I felt need for change. I ended up ordering a small assortment of the PIO'S to try from two sellers, one in Bulgaria and the other Romania. I got some MBGP, MBGO and KBG..N or M. They all test really well and are right on for capacitance and low in ESR. I know my Peak tester isn't the best but it gives me a pretty good idea of where they're at. I tried a couple different variations with some paralleled and settled on a 2uf and .5uf for the HF input in parallel and a 4uf (KBG) for the tweeter. After these settled in I noticed a definite improvement toward a more natural and realistic overall tone with instruments and voice. I try to be neutral when evaluating any changes in components staying between subjective and objective. The caps have higher ESR (max of .31) than the Sonicrafts but something in the materials used and construction process of thes PIO's made a real and audible change to my speakers sound for the better, much better. Now these are Crites type B that I built last year to get close to the Heritage sound that I just couldn't afford. I know the Cornwal IV sound very well and I will say that I'm extremely pleased with these to the point at 58 years old I feel I've finally assembled my end game system.  If you've been on the fence regarding foreign military surplus PIO'S, I would urge you give them a try. My 65.00 investment / experiment is one of the best value changes I've ever made in a sound system. Thank you "thebes" for that post which helped convince me to give them a try!20220401_162042.thumb.jpg.da1e65a7b5b31e1212add7e13bd77f99.jpg20210815_080751.thumb.jpg.55757692fdddc584d92256f5f784407c.jpg

 

I immediately believe your positive listening experiences, these PIO caps from Russia are the next thing I would like to test in my Lascala. By the way, a very low ESR is just what the vintage horn speakers don't necessarily like because the overall network impedance is no longer what it was intended to be back then. Likewise, vintage horns don't like a sharp "Q" like modern caps provide, but they like a smoother progression of xover curves.

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11 minutes ago, Tom05 said:

Russian surplus military caps , your kidding right? That’s a good way to blow up your speakers , maybe even your house.

 

Nope, we're not kidding. There's a ton of vintage caps and tubes laying around in old stockpiles over there which were built with real "effort", many from prior to the "fall of the wall": Say what you might about what they could and could not do, but those caps were some of the most bullet proof stuff you'll ever see for these purposes, these caps are sealed and "built to the hilt" in a lot of ways.

 

They also impart a sonic signature that many horn enthusiasts really appreciate. I've fiddled with a number of these caps and know well why people like them. I've come to develop more of an appreciation and preference for modern Teflons and polypropylenes but that's my way of "riding the audio wave" and not necessarily a requirement or anything.

 

 

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2 hours ago, Audible Nectar said:

 

Nope, we're not kidding. There's a ton of vintage caps and tubes laying around in old stockpiles over there which were built with real "effort", many from prior to the "fall of the wall": Say what you might about what they could and could not do, but those caps were some of the most bullet proof stuff you'll ever see for these purposes, these caps are sealed and "built to the hilt" in a lot of ways.

 

They also impart a sonic signature that many horn enthusiasts really appreciate. I've fiddled with a number of these caps and know well why people like them. I've come to develop more of an appreciation and preference for modern Teflons and polypropylenes but that's my way of "riding the audio wave" and not necessarily a requirement or anything.

 

 

I’m sure their very fine caps , just a silly joke 🤓

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I'm not sure at what point ESR becomes too high for use in a network cap, maybe .5 ohm? 

I ordered twice what I needed so I could experiment with different configurations at the same total capacitance. None of these measured higher than .31 and when paralleled that reading came way down. If this type of cap imparts some "coloring" to the sound it does it in a positive way. I say this because the audible difference is notable from the Sonicraft caps. Some may say those caps or other metalized poly types are "transparent" or " neutral" in crossovers of horn loaded speakers. To me the highs sounded  somewhat sterile with a bit of bite in the upper frequencies that I didn't care for. With the PIO's in the crossovers everything sounds more natural and correct, 3 dimensional. I don't care how they measure or how my tube amp measures, I'm totally satisfied and enjoying the music like never before.

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23 hours ago, Tom05 said:

Russian surplus military caps , your kidding right? That’s a good way to blow up your speakers , maybe even your house.

 

They build quality is insane. I've been collecting them for years. k75/k42 Metal cans with glass seal end caps. Also their k71 polystyrenes are incredible. I wish I had bought more.

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I'm another convert to kgbo and k75. They sound better suited to the horns with a more balanced sound in my AK2-1/2 and B2t networks than the various modern poly film caps I've tried.

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Glad it worked out for you (not that I'm at all surprised).

 

Now granted, I've never tried them with the later, more complicated xovers, but wherever I've put them there is a noticeable improvement, and sonically they present a full and compelling presence.

 

Hell, I even stuck a few in Marantz 8b!

 

Seems weird discussing Russian caps right now, specked and built for the Soviet military, but so it is.

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The Russian PIO caps of the 70's contained PCB's ,and so did   Domestic  products .

 

I am not sure if the 80's R..........PIO caps still contain PCB's  ?  .

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I have tried to push these caps on people because as stated the build quality is just top of the line, the price to quality ratio is very much in your favor due to the surplus nature of them and also partly the fact people think because they are old they are going to be bad which is  not true, I have purchased them for many things and haven't found a dud yet. 

 

As for the sound? The loss angle is higher with paper capacitors whether with aluminum foil types or metalized paper vs modern film types but I'm not 100% convinced that's all that's in play here. The dielectric (paper, polypropylene, polyester, etc..) have different amounts of nonlinear attributes, it can be shown on a scope easily with ceramic being the least linear and Tantalum and Aluminum electrolytics not far behind. Both of these effects, ESR and dielectric nonlinearities are small in the grand scheme of things of an audio reproduction chain but they may add up to what we hear, a difference.

 

I don't put much trust in perception due to how reality is a personal construct and differs from one individual to another. The fact that I know there can be small differences yet I also logically know this should be very hard to hear but still I've come to the conclusion that I think using them in this particular application (loudspeaker balance networks) does have some perceivable merit.

 

I am a big fan of objective testing as I firmly believe if something is different it should be measurable. I am way behind on work right now but eventually when I get caught up I'd love to do a null test with just the crossovers to see if there is actually a difference. I have AA networks and E networks, the type E networks in my 1975 Heresy's were updated with new polyester types and sound great so I probably won't do them first. The AA's in my 1982 La Scala's have the original capacitors and although the last time I measured them they passed so I left them in it's been several  years since I tested them so I think it might be time to replace them. I'll null test the two AA networks against each other with the original caps then I'll replace the caps on one of them and repeat the null test. This should give a decent indication if anything indeed changes, well at least to the point of humanly possible to measure and hear.

 

No matter how the test turns out they are what I will use when I need to replace capacitors in the AA networks.

 

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11 hours ago, RandyH said:

The Russian PIO caps of the 70's contained PCB's ,and so did   Domestic  products .

 

I am not sure if the 80's R..........PIO caps still contain PCB's  ?  .

 

The way those caps are built and sealed one would never come into contact with that, assuming that PCBs are in fact present in the Russkie caps (I don't really know the details on those). I'd probably have to swing at one with a hammer to get it to crack open, though.

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13 hours ago, captainbeefheart said:

I have tried to push these caps on people because as stated the build quality is just top of the line, the price to quality ratio is very much in your favor due to the surplus nature of them and also partly the fact people think because they are old they are going to be bad which is  not true, I have purchased them for many things and haven't found a dud yet.

 

I don't put much trust in perception due to how reality is a personal construct and differs from one individual to another...

 

I am a big fan of objective testing as I firmly believe if something is different it should be measurable...

 

 

 

 

'Test's great... sounds terrible...'

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