Sourcing Paper in Oil PIO Caps

[Melodeath00]

Does anyone have any advice in sourcing PIO caps? Are there certain ones I should look for, and is there a source besides ebay? I am very interested in sourcing some 0.5uF PIO caps to try out in my C12 and U47. The C12 currently has a .5uF polyprop, and the U47 has 1uF polyprop. Is there a source for Metal Paper capacitors? That would be more accurate than PIO for the U47, but I'd be fine with PIO for sure. Of course, size is an issue in both mics, and I'd liek to see the difference between 1uF and .5uF in U47.

I've heard everything from PIO being smoother/darker to PIO being more musical and bright. I'm curious to see the difference myself, while also making my builds more "authentic" to their vintage counterparts.

Thanks!

 

[emrr]

There are multiple new-manufacture options, along with the wealth of Soviet NOS found on ebay. 

 

[o3misha]

Todays PIO caps production technology is different from old technology. There is no thin  foil for producing PIO caps with small dimensions today.Thats why Jensen or Duelund caps are too bulky for microphones. The best way to use old Russian military caps. You can find them on eBay from time to time. With 0.5 uF you will get a bit higher resonance point than with 1uF (40Hz with 0.5 uF and 30 Hz with 1uF). Subjective feelings may be different. On the one hand, with a smaller capacitor you have less low frequencies. But because of the higher resonance you can get the opposite effect. Become less extreme bottom, but more audible middle and bottom end. Coupling cap usually selected according to the value of grid resistor. If you have a 60M, it is better to use 0.5mF​​. If the 100M, - then 1mF.

 

[Spencerleehorton]

hi guys,

i just had 2 x 1uf 630v caps delivered, these i will try in a U47 type mic, Oliver Archants Alternative schematic.

http://www.ebay.co.uk/itm/271349086522?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

regards

Spence.

 

[Melodeath00]

Todays PIO caps production technology is different from old technology. There is no thin  foil for producing PIO caps with small dimensions today.Thats why Jensen or Duelund caps are too bulky for microphones. The best way to use old Russian military caps. You can find them on eBay from time to time. With 0.5 uF you will get a bit higher resonance point than with 1uF (40Hz with 0.5 uF and 30 Hz with 1uF). Subjective feelings may be different. On the one hand, with a smaller capacitor you have less low frequencies. But because of the higher resonance you can get the opposite effect. Become less extreme bottom, but more audible middle and bottom end. Coupling cap usually selected according to the value of grid resistor. If you have a 60M, it is better to use 0.5mF​​. If the 100M, - then 1mF.

Yes, I always thought the higher the output cap value, the more low end extension. However, in Oliver's recent BV8 History article, he actually says that due to the BV8's design, it's actually the opposite. I really don't know. Only way to find out for sure would be to test

Regardless, I currently have 1uF polyprop output cap and 1G grid resistors. I want to switch to 0.5uF paper and 60M respectively, as these are the values they used when they switched to BV8. I will use 100M for backplate instead of 1G and 150M for rear diaphragm instead of 1G, as these are what they used in M49 and U48.

 

[mabell313]

So, do all BV8-style transformers have this built-in roll-off? Looking at Cinemag's website, it states that several of their 6.5:1 ratio transformers are 20~20k. Same for a few other manufactures. I am confused on which capacitor value would be correct, .47(.5) or 1uF? Definitely some eye opening information!

 

[o3misha]

Properly designed BV08 has no fading low frequencies. As for the size of the coupling capacitor , - a matter of taste . 1uF produce resonance at 30Hz, 0.5uF -at 40Hz. Neumann changed  value of coupling cap from time to time. Not least important is also the choice of the grid resistor. I do not advise anyone to use large grid resistors ( more than 100M ) in U47 . Especially if you have a vintage lamp. So there is no need to align the frequency response of the microphone. Flat frequency response has never been a strong point of U47 . Much more important is to achieve a bright and legible mid range with a soft blow in the bottom middle. With a huge grid resistor ( 1G  ???)  this is harder to achieve .

 

[Melodeath00]

Guys, do you think NOS Russian "Paper and Aluminum Foil" in Wax might be closer to "Metal paper" Tar Bosch-type caps in the U47 and M49 than Russian PIO?

It seems a lot of people use PIO for those old school cap-tyes, but what about Paper in wax? "Paper and aluminum foil" sounded like "metal paper" to me just from a word standpoint, so I've become curious about it.

 

[o3misha]

Paper in wax caps give even more vintage sound. I tested Jupiter and Duelund caps. If you like vintage sound, then PIO or PIW caps give you desired sound. But don't forget that paper in wax cap does not like heat.

 

[Melodeath00]

So looks like PIO and PIW are good choices then! Does "vintage sound" always mean less highs to you? I want to put an "authentic" cap in my C12, but I don't want me C12 to be less bright. Thanks!

 

[o3misha]

I would not say that PIO cap gives less high freq-s.  It gives different high freq-s.  The sound with PIO cap is more colored and  has more harmonic distortions . But sometimes these distortions are desirable and pleasant.

 

[mabell313]

A great capacitor is the Soviet K75's. Awesome midrange colouring with those. Once if settles in, try bypassing it with a Soviet Teflon 1/100th it's size(i.e. 1uF/.01uF). That combo is freaking fantastic but, HUGE! So, if you can fit them, try them out. You won't be sorry!  As for the Soviet PIOs, the K40's are film/foil and sound great. The K42's on the other hand are metallized PIO  and are much smaller for better fitment but do have diminishing performance as compared to the K40's. There are Soviet PIW, just do a search.

 

[Melodeath00]

A great capacitor is the Soviet K75's. Awesome midrange colouring with those. Once if settles in, try bypassing it with a Soviet Teflon 1/100th it's size(i.e. 1uF/.01uF). That combo is freaking fantastic but, HUGE! So, if you can fit them, try them out. You won't be sorry!  As for the Soviet PIOs, the K40's are film/foil and sound great. The K42's on the other hand are metallized PIO  and are much smaller for better fitment but do have diminishing performance as compared to the K40's. There are Soviet PIW, just do a search.

Thanks. I found the Russian PIW last night, but didn't know if they were well-regarded. I hope a tube mic will not be too warm

The K40 will fit in my U47 I think, but it wont in my C12. I might need to get the smaller, green K42 for the C12 or use PIW. The C12 only has space for about 35mm length, I believe, but maybe I could find a way to angle things around and still fit.

What does bypassing the coupling cap with another cap (much smaller) do?

 

[mabell313]

A great capacitor is the Soviet K75's. Awesome midrange colouring with those. Once if settles in, try bypassing it with a Soviet Teflon 1/100th it's size(i.e. 1uF/.01uF). That combo is freaking fantastic but, HUGE! So, if you can fit them, try them out. You won't be sorry!  As for the Soviet PIOs, the K40's are film/foil and sound great. The K42's on the other hand are metallized PIO  and are much smaller for better fitment but do have            diminishing performance as compared to the K40's. There are Soviet PIW, just do a search.

Thanks. I found the Russian PIW last night, but didn't know if they were well-regarded. I hope a tube mic will not be too warm

The K40 will fit in my U47 I think, but it wont in my C12. I might need to get the smaller, green K42 for the C12 or use PIW. The C12 only has space for about 35mm length, I believe, but maybe I could find a way to angle things around and still fit.

What does bypassing the coupling cap with another cap (much smaller) do?

.                                              Bypassing can do several things. It can extend freq. response as well as smooth out the sound of the larger cap. It can also add distortions of its own. Not always a bad thing I might add. The K75/Teflon combo happens to just work with the K75's beautiful mids and the teflon's smoothness/frequency extention pairing perfectly. Teflons and PIOs do not always make the best bypass caps. They just sound too different as compared to most metallized poly caps. A better choice for metallized poly would be an actual film and foil cap. Some combos do not work so well together or really do nothing at all. I was just reading yesterday about bypassing a large cap with a smaller cap of the same exact type to help clear up and extend high freq response. They were also talking about Deulands too so, money money! There definitely is a point of diminishing returns. Bypassing allows you to use a large, cheaper cap and gain some of the sound qualities of the smaller cap letting you purchase a far higher quality/cost cap rather than just using the quality cap in the size you need. That would break the bank and probably not even fit. My Apex 460 has a 10uF metallized Panasonic bypassed with a .1,160V Soviet K42 PIO just waiting to be burned in. Please do not ask about fitting both of those monsters on the stock PCB, it was terribly hard and I had a friend help.

 

[o3misha]

You may use Jupiter PIW cap 0.47uF/630VDC. It can be fited in  U47 body without problem. Sound is much better with Jupiter than with Russian PIW cap and it is not necessary to use additional bypass cap.

 

[mabell313]

The Jupiter indeed does not NEED a bypass but, could benefit from the right cap. Its all a matter of taste. Speaking of which, at the price point of the Jupiters it is just a matter of taste again as really most of those pricey caps sound good. They all may not be to everyone's liking but, you DO get what you pay for to a certain extent. Yes, there are some budget caps out there that do sound very good but when compared to something like say a V-Teflon, they are crap. Plain and simple. Again, beauty is in the eye of the beholder. On the other hand, most of the high dollar caps beat out everything else in terms of resolution.