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Old 2nd March 2013, 10:04 AM   #111
DF96 is offline DF96  England
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Mylar is polyester. Polyester is known to be a slightly non-linear dielectric. OK in most cases but not a good idea to use it for the cap which sets the LF rolloff as it then will, by design, have signal voltage across it and so could create distortion. People who prefer Mylar or other polyester caps may be expressing a preference for a little low order distortion with their music. This may be why polyester caps are particularly popular in old guitar amps, so much so that it has driven up the price of old perfectly ordinary caps such as Mullard mustards.

Apparent changes in sound after a few hours of use are probably due to acclimatisation. That is, ears/brains getting used to the sound. This happens all the time. It is why we can endure the awful lumpy frequency response of a typical loudspeaker/room setup, and why we don't usually notice the huge change in frequency response when we move our head a little.
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Old 2nd March 2013, 10:16 AM   #112
mach1 is offline mach1  Australia
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Dear Df96 ( I built my first regen radio with a DAF 91!) i don't want to get into a debate about the running in of components, however I will say that these caps, when properly utilised make a mockery of a lot of overpriced rubbish.
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Old 2nd March 2013, 10:22 AM   #113
DF96 is offline DF96  England
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Almost any normal decent commercial/industrial quality cap can make a mockery of some overpriced rubbish. In some cases because, allegedly, the expensive stuff is just a pretty case around a normal cap. In other cases the expensive stuff is markedly inferior to normal stuff, because it is 'hand-made' or poorly designed by someone who knows more about retail economics than component engineering.

Sorry for butting in on your capfest, but I thought people ought to be told why Mylar/polyester might sound different.
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Old 3rd March 2013, 11:37 AM   #114
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Mach 1,
thanks for your comments about burn in time and that with use they become neutral - for some years now that has been my goal - neutrality does'nt mean bland it means letting the music through. It's going to be some time before I become blase about these caps.

Good news on the glare front - it's gone. I decided the easiest change to make was to lower the gain by 3 dB in the phono stage and it worked. Which leaves a brightly lit sound stage, I always have a laugh when I hear 'the music comes from an inky background - when the hell did anyone hear live music coming from a dark, inky background. I can only remember one concert in a technically correct acoustic environment and that was the Congressbouw in Den Haag in 1980 - Weather Report. It was a completely soulless evening - I can't remember another with any genre of music.

Looking at other threads about removing the outer shells of some Russian Teflons gave me an idea - instead of removing the outer casing of these PETPs why not just damp the casing like many of us do with a chassis? It's worth a try and is reversible if the result is negative or neutral in effect. I should say that I use AFC (active fan cooling) so values don't drift as they can and do with innefective passive cooling.

DF96 - reading your posts, they all seem to be theoretical statements which have zero value to anyone in the real world - remember what the fatman said "all theory must come from practice to have any real value".

Have you actually used these caps, I doubt it. There is no distortion using these caps in the signal path, indeed quite the opposite - I have played LPs that I know from decades of listening and only last night played Joni Mitchell's 'Shadows and Light' so much previously masked/hidden details emerging, the guitars sounded just like they should (it's a live recording) piano deep with notes going on and on.

DF96 you need to drop the theory posture and try actually using empirical research to justify what you say. Virtually all those who have tried these caps have been impressed. Pre-Sapian found them to be really bright and glaring - he did'nt make that statement from theory but from practice and so must be treated with respect, indeed he may be making others think carefully about using them in x/overs - that's what I call useful input.

Now here's the thing - I shall try using a polystyrene for the 0.1uF position and a 1uF/250V 1% PETP for the main coupling cap. I may just shell out for a pair of 0.1uF V caps - they are not too expensive at that value but only if I'm not satisfied with other combos. I shell out for Z foil Rs because they disappear and cannot tolerate the awful muddy sound that supposedly quality boutique resistors create - these PETP caps do the same but a damn sight cheaper - I repeat buy with confidence.
Black Stuart
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Old 3rd March 2013, 12:38 PM   #115
qusp is offline qusp  Australia
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no, hes not speaking from theory and I dont think he was talking about massive audible distortion. You think there is no distortion because you cant hear it over the fan? PET is not a very linear dielectric, that is not theory, but fact. He does not have to use this specific PETP cap to know that. that old comeback to throw at anyone making criticism of something that they have to have heard that specific brand generic part is pretty tired.

who said 'all theory must come from practice to have any real value'? whoever it was didnt have a very good command of the English language.

its funny when people simply will not accept that what they like about something is the low order distortion profile/distribution. There is zero shame in it, we are in this for the enjoyment right? Nelson Pass and that gang have no problem admitting it, thinking that there is a special 'harmonic transparency' is delusion

what Empirical research have you been doing?

Last edited by qusp; 3rd March 2013 at 12:43 PM.
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Old 23rd March 2013, 03:13 PM   #116
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your post is neither honest nor rational. You fail to mention that you have never tried these caps so your comments have no value. You also query the self evident fact that unproven theory has only one advantage over a fart - it does'nt smell but it does make you look silly does'nt it.

You also fail to mention that you have spent loads of money on Dueland and other exotic boutique capacitors in the past (see your boasting over the same on Head-fi), so here is a cap that proves you have been a real chump to spend serious money.

So ' you don't have to listen to a part to know how it sounds' - hilarious but somehow sad at the same time.

To make a statement about fan cooling and in particular my amp and it's method of fan cooling which you state is noisy are the words of someone who has serious problems dealing with the real (not imaginary) world - you have never heard my amp - do you not see how ridiculous you are? I don't know why the mods hav'nt stepped in to deal with you.

To the rest of the posters who have contributed rationally to this thread - I now cannot agree with one comment by the OP - that there is little difference between the Russian PETP caps.

I tried the 1uF/250V 1% K73P4 and found that it did a good job at sitting on the 0.1uF cap that preceeded it, it may well be better in another system but I doubt it.

I bought 4 x of the K73-16 1uF250V +/- 10% I like to match as accurately as possible coupling caps, so I measured these - 0.960/0.961/0.967/0.932.

I've only had about 10 hours using the K73-16 0.1uF & 1uF - I use the Alps Blue that came with my hybrid amp but I shunt it with Z foils. This means I get a drop of about 6dB. This would'nt normally be a problem but I get about 3-4W of class A and my speakers (Heybrook Sextets MK1V) are only 89dB.

So yesterday I decided to up the gain by 3dB in my phono stage - wow, the brightness/sheen/glare has gone completely (it did'nt take 100 hours). I can't accept that making a small change to the gain is responsible for removing the one niggle I had with these caps, whatever it's gone.

We all have our favourite LPs/CDs to test any change with. One of my favourites is the ECM - Making Music with Zakir Hussain/Hariprasad Chaurasia/J McLaughlin and J Gabarek - beautifully recorded, ECM had the nack of putting you alongside the recording engineer. If you have a bright system this recording will throw it right back at you.

When I first played this using just the one 01uF PETP cap - it was so euphonic, nice but not accurate and Jans' sax came at me but this time it sounded incredible from top to bottom. Playing Sara Mclaughlin's Surfacing - well I have never heard her sound so real. Hariprasad's flute - magical emotion.

I'm sick and tired of all this rubbish about 'black backgrounds' totally false, nothing like real world music. They are a bigger revelation than Z foils for me (Caddocks do the same for others). They just let the music through. So much is lost with crappy signal path caps - these let you hear real dynamics, depth, detail, bass and a top end that taper's away into infinity. OTT comments - for a few dollars you can find out if I and the others on this thread are away with the fairies (certainly one poster needs to pull his neck in).

After a few weeks I still find it hard to accept the outrageous difference these PETP caps have made to my whole system - from a grudging acceptance that my AT33V and MC3 phono stage are OK to being as happy as Larry and even more astounding that that first little 0.1uF cap could so transform a Chinese hybrid amp into something that is definately streets ahead of a heavily modded KT88 amp and indeed I can see now that apart from getting rid of those awful Solen o/put caps and tweeking the PSU - that's it.

Now if only I could find a pair of 0.0022uF PETP to use as load caps in my phono stage - hell that's too greedy, I'll settle for this.
Black Stuart
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Old 23rd March 2013, 03:58 PM   #117
AndrewT is offline AndrewT  Scotland
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Originally Posted by Black Stuart View Post
1uF/250V 1% K73P4
little 0.1uF cap........
the above references I find easy to read.
.........a pair of 0.0022uF ..............
I can read 2n2F far easier than reading 0.0022uF. I have to count back through the zeros.
regards Andrew T.
Sent from my desktop computer using a keyboard
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Old 23rd March 2013, 05:46 PM   #118
DF96 is offline DF96  England
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Originally Posted by Black Stuart
DF96 - reading your posts, they all seem to be theoretical statements which have zero value to anyone in the real world
People who think knowledge is unhelpful have to get by with ignorance instead.

One of the things which makes us humans different from animals is that we can learn from each other via things like writing and reading. That saves us all from having to experience everything we need to know about. The theoretical knowledge that I should not step in front of a moving vehicle has stood me in good stead for many years. I guess if I lived in the 'real world' I would have to try it for myself just to see what happens.
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Old 23rd March 2013, 05:55 PM   #119
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Originally Posted by Black Stuart View Post
"all theory must come from practice to have any real value".
I like this one much better:
Originally Posted by James Clerk Maxwell
There is nothing more practical than a good theory.
The missing link between lead and gold in alchemist's world was BS and commerce.
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Old 23rd March 2013, 05:56 PM   #120
RNMarsh is offline RNMarsh  United States
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Regardless of the make and brand and dielectric etc, try to NOT use metallized film in a speaker cross-over for the bass or bass-mid cross-over caps. The solid foil type are needed for thier higher current capacity to remain stable in performance. But you do have to use higher voltage rated ones if they are film/foil type. Use at least 2X power amp supply rail voltage.

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