Large Oil Capacitors

[TheMooN]

Gentlemen ~ I would appreciate a little advice please

I would like to Cull the electrolytics out from a couple of Mullard 5-20's and have been mulling over the ASC Oil/Poly cans .

I was wondering whether anyone has any experience with these as I am looking to replace the 16uf+16uf 450v electrolytic with pairs of 20uf ASC's if I can shoehorn the bugger's in !

Tvm .

[alexg]

I have been using ASC motor runs and I really like them.

A bit "slower", I was told, but it seems to sound better than electrolytics that I have tried (Nichicons and Nippon Chem).

I use them on my tubed amps and preamps.

The only thing I hate about them is too much real estate that they occupy for small capacitance they provide.

[Sherman]

I have also been using ACS motor run caps in my power supplies. They have been working well. I have not used them in any other position in an amp yet (bypass, coupling).

If there is a drawback it is their size. I've drilled holes in my top plates and let them project through, mounting from underneath with mounting clamps.

[soundbrigade]

The biggest disadvantage is that when the paper-caps are wound they are pressed into a more oval shape. This pressing introduces pockets of air in the capacitor which gives a high degree of distortion, making paper-in-oil caps absolutely unusable for audioapplications, though they are very hype now.
In a PSU they may work, but remember that a PiO-cap also has a very high degree of tgd (tan delta or loss factor) compared to plastic caps.

[Sherman]

Originally posted by soundbrigade
The biggest disadvantage is that when the paper-caps are wound they are pressed into a more oval shape...

Not sure what you mean by oval shape. All my ASC caps are round cans, not oval.

[Miniwatt]

Originally posted by Sherman



Not sure what you mean by oval shape. All my ASC caps are round cans, not oval.

I think he means something like this:

[soundbrigade]

A capacitor winding is wound round. Then it is sintered and at the moment the winding is mechanically pressed into an oval shape. Connections are solded to the ends of the wound cap and put in a can and filled with oil.

The process when the cap is sintered gives "holes" between layers in the the winding and these holes causes odd harmonic distortion.

A plastic (polyprop) cap is sintered using heat that makes the plastic shring and tightening the wound cap, closing in any cavitities.

And I repeat, using a PiO in a PSU is OK I guess but using it in signal routes is definitely not recommended.

[dhaen]

Is the PSU not part of the signal route?

[soundbrigade]

We use to consider an amplifier as a device that modulates a DC-signal coming from a PSU...

My point was to show some of the problems involved in using components that are "fashing of the day" without considering the flaws and disadvantages these components present.

[pedroskova]

The ASC's are not PIO, but rather, metallized polypropylene motor run capacitors that are immersed in some form of "oil". They can be had in round or oval shapes. They're my cap of choice in psu's...tough, reliable, and cheap compared to the boutique caps.