I found them good but always used with plenty of DC across them; the electric field has to be sufficiently strong to compete with the typical thermal energy of molecular collisions and allow the permanent dipoles to allign. I think this is right but ask DF96 about this for a definative answer.
Thanks for you quick replay. I might go for another type instead - 1uF 200V PIO K40Y-9, or just shake more my wallet and order some Sonicaps and stay safe
I think my reasoning in post 61 is wrong; plugging some numbers in suggests than to completely allign the permanent dipoles in a polar dielectric would require an electric field of some gigavolts per metre. Maybe the DC simply has to be an order of magnitude more than the AC signal. The topic of using polar dielectric caps with DC across them to negate the HF loss often comes up but I haven't seen any science to back up the conventional audio wisdom. Perhaps some of the professional scientists on the forum could comment....
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Hi, I was much influenced by member pietro7 and his great experience with petps http://www.diyaudio.com/forums/tubes-valves/148554-my-aikido.html#post1895976 as he used them in the signal path as well,
also by member audiojoy who's got thread about these caps here on forum as well http://www.diyaudio.com/forums/parts/143675-petp-capacitors-one-best.html
Don't know what did you mean by parallel them, because those I use already are 1 uf caps?
cheers
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Can you (or anyone) explain the difference between the K75-10 and K75-24? I bought some K75-24 for coupling in my el34 pp monoblocks, and now I wonder what´s the difference to the K75-10??? Any idea??
K75-10 - its dielectric is claimed to be a hybrid of paper and polyethylene terephthalate, which is essentially a type of Mylar, saturated in oil.
K75-24 PLIO is combined Papier / Lavsan in Oil
(Lavsan is the trade name for a polyester fiber manufactured in the USSR; the equivalent of Terylene in Great Britain, Dacron in the USA, and other polyethylene terephthalate fibers manufactured by a variety of production processes.)
There is some debate as to which Russian “oil” capacitor is the best some report K75-10 is the premium oil capacitor out of the Russian military.
Others claim that K75-24 also have excellent sonic characteristics.
I have recently added/replaced Wima's MKS in my Music Angel preamp. with four of K40Y's and there is huge improvement in the sound. Also in my other units where I replace original caps with Russians (USSR) hard-core caps I hear difference, clearer and 'beefier' sound.
Try K75-24 and hear how they sound in your device, and let us know. I believe you can't go wrong with the caps that are built to withstand a nuclear war.
Hi Jadran,
thanks for your quick response. I ordered the K75-24 since the values that i needed (0.22 and 0.47 at least 600v) wasn't available at the moment for the K75-10. I also planned to buy K40y but I ended up with K75 which suppose to have better (addictive) midrange comparing to K40y. I guess for that kind of money we talk about here, I will also order K40y just to experiment.
Here's the pciture of one of my monoblocks during production. I actually wanted to use vintage russian caps all over but my tech talked me out of it since the values were hard to get. So we ended up with JJ electolytic (the brown Samsung caps are not there anymore) and K75s. I also considered using K75 10uf instead of the Scr but I can't find it nowhere..
thanks for your quick response. I ordered the K75-24 since the values that i needed (0.22 and 0.47 at least 600v) wasn't available at the moment for the K75-10. I also planned to buy K40y but I ended up with K75 which suppose to have better (addictive) midrange comparing to K40y. I guess for that kind of money we talk about here, I will also order K40y just to experiment.
Here's the pciture of one of my monoblocks during production. I actually wanted to use vintage russian caps all over but my tech talked me out of it since the values were hard to get. So we ended up with JJ electolytic (the brown Samsung caps are not there anymore) and K75s. I also considered using K75 10uf instead of the Scr but I can't find it nowhere..
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Nice looking build, although the fuse holders look like the side tab is awfully close to the chassis. YOu might also add rubber grommets where wires go through the chassis.
I've used FT-1, K40 and K42 capacitors and have been pleased with all three. The FT-1 I've only used as input caps.
I've not tried K75s.
If you experience any hum issues, you might try to rework your heater wiring and twist the wires.
I've used FT-1, K40 and K42 capacitors and have been pleased with all three. The FT-1 I've only used as input caps.
I've not tried K75s.
If you experience any hum issues, you might try to rework your heater wiring and twist the wires.
Hi Derik, that monoblock looks awesome, good luck with further mods.
Although there is some spare room I doubt you could squeeze larger Russkie caps, like 10uf?
Those of 4,7uf are already 95mm long. There is also one site I'm checking right now, beside ebay, Russian tube store, Capacitors, Resistors, Dosimeter - Sovtube - Russian Radio components they ship from Ukraine, a lot of interesting stuff could be found there.
cheers
Although there is some spare room I doubt you could squeeze larger Russkie caps, like 10uf?
Those of 4,7uf are already 95mm long. There is also one site I'm checking right now, beside ebay, Russian tube store, Capacitors, Resistors, Dosimeter - Sovtube - Russian Radio components they ship from Ukraine, a lot of interesting stuff could be found there.
cheers
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Having read the whole thread now, I am puzzled by one matter.
Coupling caps - they are supposed to have negligible reactance over the audio band, yes? Any di-electric contribution et al is therefore also negligible, at least with any half-decent capacitor. (There are umpteen articles listing the low percentage effect of characteristics - very generally revealing small fractions of a percent.) Coupling caps are thus mostly d.c. blockers; they do not charge/discharge during operation to any audible effect. Of that negligible effect one must now calculate the negligible di-electric contribution ....
How can one then talk of audible effect - which audible effect, if simple interpretation of tests shows that any such is way below hearing threshold?
Secondly, with respect, I read of "in the signal path". Power supply capacitors are equally in the signal path as are bypass capacitors. Signal current is a.c.; it flows in a circle, thus just as much through the 'return' path of a power supply or a bypass capacitor - which again is supposed to have negligible reactance at audio frequencies etc.
I fully respect listening tests' results quoted by members - I was not there to dispute the same. But I do maintain the above begs some explanation unless one wants to turn basic electricity on its back. (This of course excludes capacitor effect in filters where their finite reactances act very definitely - their job is to cause frequency discrimination.)
Coupling caps - they are supposed to have negligible reactance over the audio band, yes? Any di-electric contribution et al is therefore also negligible, at least with any half-decent capacitor. (There are umpteen articles listing the low percentage effect of characteristics - very generally revealing small fractions of a percent.) Coupling caps are thus mostly d.c. blockers; they do not charge/discharge during operation to any audible effect. Of that negligible effect one must now calculate the negligible di-electric contribution ....
How can one then talk of audible effect - which audible effect, if simple interpretation of tests shows that any such is way below hearing threshold?
Secondly, with respect, I read of "in the signal path". Power supply capacitors are equally in the signal path as are bypass capacitors. Signal current is a.c.; it flows in a circle, thus just as much through the 'return' path of a power supply or a bypass capacitor - which again is supposed to have negligible reactance at audio frequencies etc.
I fully respect listening tests' results quoted by members - I was not there to dispute the same. But I do maintain the above begs some explanation unless one wants to turn basic electricity on its back. (This of course excludes capacitor effect in filters where their finite reactances act very definitely - their job is to cause frequency discrimination.)