well and that and the inherent unreliability of "listening tests" based on memory of needle drops after serial modifcations the hardware
I dont do so much swapping these days..well years really, just research and selection of the best part for a job, then buying and placing that part in the build. I try and avoid caps completely in most cases anyway, so when I do have to use them, as the lesser of 2 evils, I do often go a bit overboard with price.
I didn't say listening test really, I said measure the frequency response with a mic and test equipment. Just don't buy the cheapest component you can as there may be a reason it is cheap such as poor construction, but if you have seen a high speed capacitor winder I doubt that very many companies make those machines and the same with the actual film materials.
yep, mostly dupont film I suspect, not sure about the machines
dont virgins come into it somewhere?
dont virgins come into it somewhere?
qusp,
Most of the film that I saw at the manufacturer that I knew was actually German origin. Supposedly the highest quality at the time. And this place was making their own branded caps and also some of the high end boutique caps with stranded wire leads. All on the same machines and with the same films.
Most of the film that I saw at the manufacturer that I knew was actually German origin. Supposedly the highest quality at the time. And this place was making their own branded caps and also some of the high end boutique caps with stranded wire leads. All on the same machines and with the same films.
qusp,
I think that just the name maybe is still in the domain of DuPont, but PTFE film is made around the world at this point by many manufacturers. Those days are long since over that they control the material I would think.
I think that just the name maybe is still in the domain of DuPont, but PTFE film is made around the world at this point by many manufacturers. Those days are long since over that they control the material I would think.
qusp,
Unless you are updating or changing your formula I think you only get 17 years for a patent. After that it is game on for others. That is why companies will make new claims at set intervals in time to retain the advantage of a patented product. It does take development to stay on the for front of technology and protect your IP.
Unless you are updating or changing your formula I think you only get 17 years for a patent. After that it is game on for others. That is why companies will make new claims at set intervals in time to retain the advantage of a patented product. It does take development to stay on the for front of technology and protect your IP.
aha OK, thanks for that info, however international IP rights is hardly enforced immediately now in some parts of the world. so as you say, best just keep developing and keep the copiers at bay by brute force alone
😀
Comparing the same values with differing volume bodies would also be interesting, also long term tests with quite a high low frequency content at a sensible operating voltage, would give an indication of any changes during use due to temp rise etc. Testing under stress and at extremes of operating conditions can also give useful data. It will show a difference between high and low grade components. To realy stress them a proper test chamber would be the thing, but probably a bit extreme for home audio, though again the results would be interesting...Then add a vibrating table to add some shake rattle and roll to the equation. This is done in industry especially critical situations (which these days its quite often automotive, more electronics, life critical, harsh operating envoironment) I wonder if there is any published data, have to have a look.
Marce,
I like your thinking on the test conditions. I would add that typically size has a lot to do with voltage rating more than anything else, so that should also be a controlled condition that the voltage ratings are the same for an accurate test.
I like your thinking on the test conditions. I would add that typically size has a lot to do with voltage rating more than anything else, so that should also be a controlled condition that the voltage ratings are the same for an accurate test.
not just voltage rating, but parasitic inductance and its ability for the foil to act as an antenna relates to size and expensive audio film caps are often huge, meaning especially in signal applications that can meaningfully degrade circuit layout
Any recommended RIAA caps? I know there are some good NOS polystyrene, but they are imossible to find in the values need, which are 47nF and 15nF.
My dad used several polymer types by DuPont in my middle/high school days to manufacture products, including rolls of PTFE sheet.
I sorta grew up between piles of DuPont boxes, the logo stamped on them is/was hard to miss.
Back then, before the onset of the first Asian industrial wave, IP/Patent stuff may not have been as fierce yet.
For an example : in those days, men's pants often/usually had strips of plastic sheet stitched between the woven layers in the front.
Some 1.5" x 10" size, to make the area of the button/hook more rigid.
The ones "we" manufactured were made of Nylon, tens of millions, stamped from rolls of DuPont sheet.
(I sometimes helped out to stack the punched strips back into the boxes, seen enough DuPont labels go by for the rest of my life)
In those days, competition between polymer manufacturers may have been more "regionalized".
Here it was DuPont who had a large hold on the market, in France it may have been another manufacturer.
Comparitive example : Akzo nobel here developed their aramid fiber Twaron, simultaneous with DuPont's Kevlar.
For years, the two were in legal war trenches, untill they agreed that each covered it's own back yard.
Sometimes miss the good old days, experimenting with diy Teflon boards is easy if all you have to do is drive down, for a box pick-up freebee.
The variety of PTFE usages still continues to admire the stuff, from audio to non-stick pans, from Gore-tex shoes/clothing to various technical applications.
Last edited:
Thom, see may article in Linear Audio Vol 2 for a listening test method for capacitors and my results to date.
As a side note, Hewlett and Packard made some dandy test equipment in that garage. They did not do anything that was outside the bounds of basic physics and engineering. No "quantum alignment of cryogenic domains" or silly stuff like that.
PTFE is available from several manufacturers. It has some distinct disadvantages for audio.
As a side note, Hewlett and Packard made some dandy test equipment in that garage. They did not do anything that was outside the bounds of basic physics and engineering. No "quantum alignment of cryogenic domains" or silly stuff like that.
PTFE is available from several manufacturers. It has some distinct disadvantages for audio.
Water-jets have distinct disadvantages for yachts.
Yet they're by far the best propulsion system, from 14ft up.
(just don't push a crude oil tanker with them
)
Yet they're by far the best propulsion system, from 14ft up.
(just don't push a crude oil tanker with them
)
The Hewlett Packard reference was a bit facetious on my part . From what I know only the 201 oscillator their first produce was really about only one produced in the Garage. My stretch of an analogy was HP made a purpose designed and built product that at the time was way cheaper than the GenRad unit . True it was with out the snake oil spin. My understand of coupling Caps at least in tube gear was because of a desire to reduce power supply cost and complexity . Given 800 dollars for silver teflon each the cost of a power supply that enables dc connection throught the circuit sound to me like a plan.
Please say more about the disadvantages of ptfe ( other than cost of course ) that is of great interest.
Last edited:
Triboelectricity and lousy mechanical properties (e.g., tensile strength, which limits the winding tension). The material is also soft, which means compression sensitivity- perhaps that's why some of them come packed in a metal can. Polypropylene is far superior in these regards.
The most microphonic caps I've ever tested were very expensive "audiophile" Teflons.
The most microphonic caps I've ever tested were very expensive "audiophile" Teflons.
- Status
- Not open for further replies.