PIO upgrade from polypropylene - worth the effort?

[Purplenoise]

Confirmation bias?

Nope. When it comes to electronics I am a total beginner compared to some brilliant minds around here but I have been recording and playing music for 30 years…I have been doing this for too long to “want to believe stuff”. I have tried it and the differences are there. Sometimes subtle sometimes not so subtle…sometimes negligible.

 

[Newmarket]

Nope. When it comes to electronics I am a total beginner compared to some brilliant minds around here but I have been recording and playing music for 30 years…I have been doing this for too long to “want to believe stuff”. I have tried it and the differences are there. Sometimes subtle sometimes not so subtle…sometimes negligible.

tbf I don't think the general issue is whether there is a difference. Rather it's whether it can reasonably characterised as an "upgrade". Esp given that there sre likely to be a significant differences between any individual PIO caps.

 

[McIrish]

I think I might be constrained by the area in which I have to work with. Quite possibly, a film cap is the only thing that will fit there. Time to do some measuring. Thanks for all the help.

 

[Purplenoise]

tbf I don't think the general issue is whether there is a difference. Rather it's whether it can reasonably characterised as an "upgrade". Esp given that there sre likely to be a significant differences between any individual PIO caps.

Exactly right.

 

[inkster]

I never use vintage caps(NOS or otherwise) without testing them for leakage at operating voltage...I've seen a number of transformers in vintage mics lose a winding from a leaky cap.
A nice modern PP cap should sound great.

 

[Ricardus]

Nope. When it comes to electronics I am a total beginner compared to some brilliant minds around here but I have been recording and playing music for 30 years…I have been doing this for too long to “want to believe stuff”. I have tried it and the differences are there. Sometimes subtle sometimes not so subtle…sometimes negligible.

This just tells me you're not understanding confirmation bias.

Our ears suck, and our brains lie to us. No matter how much you think not, and no matter how hard you try not to let it happen.

 

[Purplenoise]

This just tells me you're not understanding confirmation bias.

Our ears suck, and our brains lie to us. No matter how much you think not, and no matter how hard you try not to let it happen.

I know what confirmation bias is very well. That’s why I don’t judge only with my ears but with the ears and brains of engineers that I trust their “hearing”.
Blind test, 5 recordings, 3 of them with the same cap ( to avoid placement differences) and the other two with different caps. They picked out the differences consistently.
If I still have the tests I’ll send them to you.

 

[Mr. Moscode]

This just tells me you're not understanding confirmation bias.

Our ears suck, and our brains lie to us. No matter how much you think not, and no matter how hard you try not to let it happen.

That leads to bad marriages . . .

 

[Mr. Moscode]

Not all PIO caps are ancient. Mundorff makes some great ones, gold silver in oil, highly prized by the audiophile crowd (no nasty remarks, please). However they are usually large. I use them in upgrades and the difference is huge over a MIT/Relcap PPFX. Everything is bigger, bass, depth, smoother hi end. 2MFD/600 volts. Won't fit in your mic though.

It seems rather easy to make a swap in that mic so nothing ventured, nothing gained. The thing is it has to sound as good a week, a month or more after you make the change so some break in time should be given before the final verdict. If it makes you feel good about it after some time then it's the right choice for you. You can always go back.

IMHO these PIOs have internal damping, paper in oil, which may or may not take you where you want to go. In a mic, there isn't high current or voltage so damping may be of little consequence.

Let us know how it turns out.

 

[emrr]

Old american bathtub paper in oil are almost always perfect condition if NOS or lightly used and in good physical condition. ESR is much higher than a modern cap. I’ve seen several so used that they rolled off treble with the ESR levels, but maybe none shorted under expected conditions. They can have a very nice distortion. I’ve definitely had several old module cases with original PIO and modern film to compare and they are very different. Depends on what you like.

 

[xeawr]

Somewhat OT, but I found that in U87 clones a "cheap "electrolytic on the output (before the trafo), like the Jamicon one Neumann uses in their current verison of the mic, sounds subjectively better than a high quality polypropylene cap of the same capacitance.

interesting. Do you have a pic of such a U87a?

 

[xeawr]

I know what confirmation bias is very well. That’s why I don’t judge only with my ears but with the ears and brains of engineers that I trust their “hearing”.
Blind test, 5 recordings, 3 of them with the same cap ( to avoid placement differences) and the other two with different caps. They picked out the differences consistently.
If I still have the tests I’ll send them to you.

haha, I often took it one step further and played back blind tests to musician and non-musician friends, girlfriends, everyone that was willing to really concentrate on these files for more than 30mins. If somebody couldn't tell a from b 70% of the time, to me, this was pure chance.
The results have always been clear. Differences in cap choice/material can be heard, I scratch my head every time I'm at the guitar/pedal building platforms, where every one agrees that this is pure nonsense...
Sorry, this was a bit off topic. Anyway, I have really liked ERO MKC (PC) caps, but they are very hard to find. PP is usually good (WIMA, Panasonic), sometimes lacks character though.

Cheers

 

[living sounds]

interesting. Do you have a pic of such a U87a?

What do you need a picture for? It's a black Jamicon electrolytic cap. It's in the U87ai I bought last year.

 

[Khron]

Gotta love penny-pinching in products with a 4-figure price tag...

 

[johnR]

Confirmation bias?

Not necessarily.

Different capacitor construction types can sound different due to the electrostatic forces squeezing the electrodes together or moving them apart, changing the capacitance slightly as the signal voltage varies. This can result in audible harmonic distortion.

The more resistant the construction is to this movement, the lower the distortion.

In the case of PIO there's the additional factor of high dielectric absorption, which may have an effect on transient response.

Cyril Bateman's articles on capacitor sound are worth reading:
https://linearaudio.nl/cyril-batemans-capacitor-sound-articles

 

[Delta Sigma]

Whether I actually did, or not; I'm sure I heard a difference between a film and MP cap in a U67 build. The difference was much smaller than capsule, transformer, circuit design and tube changes.

After two years, it failed. It failed very slowly. First, there was low freq (below 40Hz) noise. Then there was audible noise. Replaced it with a film cap, and it was like taking a blanket off the mic. I don't plan to use NOS caps anymore. I replaced all my NOS caps with modern film caps in all my mics, except my M49 (ran out of film caps).

 

[living sounds]

Gotta love penny-pinching in products with a 4-figure price tag...

That's the thing, I tried high-quality polypropylene caps in the clones but the Jamicon electrolytic sounded more suitable.

 

[Khron]

That's the thing, I tried high-quality polypropylene caps in the clones but the Jamicon electrolytic sounded more suitable.

One can only wonder what the impressions might've been, had it happened the other way around.