[JamieMcC]

  I got a bunch of .3uF K71-7's basically for free. So I taped three together and used them as my first experimental bypass on the Cracks CRCRC power supply. I got this S&H 12AU7 and found it to be a little wimpy in in the bottom end but nice everywhere else. Right away I could tell the bypass with the Russian polystyrene seems to have been a good move.

  Its only ~1uF. Is it placebo?

 
Funny enough for some fun I have been trying the K71-7  for bypassing on my JFX films and then with the Epcos pio 100uf motor runs that I'm also trying out in the coupling spo  along with some bypassing with Hovland Supercaps I brought used off of the bay.
 

 

 

 
Edit also rolled in a pair of Jantzen Superior Z caps
 

 

[dimkasta]

I got a suggestion from Salas to minimize the wires of the bypassing cap and/or use some big gauge wiring for those places.
 
The improvement I got was significant. The sound is quite more coherent. Granted, I use very thin silver wiring, almost 32awg, but still, I did not expect anything like that.
 
Further on my tests, K75-10 10uF bypassed with FT-3 0.1uF once again reveal their very nice colors after some more breaking in...
I am still waiting for the smaller ones, but to be honest I am done experimenting with that spot... On to the speakers now

 

[dimkasta]

I just received the Russian silver mica caps at 1nF.
 

 
 
As soon as I got home I went straight for my DCB1 and installed them piggyback on my K75-10/FT3 set.
 
Initial listening is that the sound is brighter, clearer and bitey-er. Imagine kind of like what K75-10 does for the mids, the silver mica seemed to have done for the mid-highs. To better pinpoint the frequencies, imagine violins playing high notes. The entire top end is clearer in fact, although not as clear as I would want it so far (single FT-3 sound for reference).
 
However, bass is significantly reduced in volume and feels slower, while at the same time there seems to be some incoherence in the sound. I will leave it there for a few days to break in a bit, but I am beginning to think that 3 caps are too many to produce a coherent result.
 
The smaller cap seems to allow an airier result though, so if that does not work very well after all, I will try removing the FT-3  0.1uF and keep the mica in its place for a test. And perhaps even try a 10nF FT-1 teflon too.

 

[dimkasta]

I left the CD playing all night yesterday, and had a fast listen before going to work.
 
I think I will love this combo

 

[dimkasta]

A week has passed using the K75-10/FT3/SGM combo (10uF/0.1uF/1nF) with about 30 hours of usage.
 
I completely love it!!! And it still has much way to go into breaking in....

 

[dimkasta]

I received the K75-10 at 4.7uF yesterday.
 
I told myself that I would not try them but who was I kidding...
 
As a size, they are the same length with the 10uF ones (10cm), but half in diameter (~2.5cm)
 
I soldered them directly replacing the 10uFs keeping the 0.1uF FT3 and 10nF SGM bypasses, so that I made a direct comparison to the sound I already liked.
 
First impression was that bass was thin. Granted, going half in capacity means one octave less bass... Ok it was a bit of a stretch going for the ~7Hz optimal bass that the big ones give (22K input impedance on my monoblocks). The 4.7s give ~15Hz optimal.
 
However part of the thinness is surely due to the recent soldering and fresh caps. This effect usually goes away in a day or two, so I will be back with this.
 
Now on the sound...
I do not know if it is because of the less deep bass, but I feel that i got a very obvious improvement in clarity.
On top of that, there were two areas that I did not like. First the bass had more lower end and no punch, no impact. With the 4.7uF I am starting to get some of this impact back. This is especially obvious in higher bass frequencies. For example when a guitarist hits his guitar.
The second part was that in some cases mids and mid-highs had a dark quality. On that, I tended to attribute it to the recording since in other occasions the sound was fine. But with the 4.7uF all I can say is WOW... strings, pianos and guitars are now what I know them to be... for lack of a better word I want to say fresher? Damn I hate to love those audio-phool words
 
It is weird how when something is objectively or subjectively impressive you keep making excuses for it....
 
Anyway, I really miss the bass for now... I hope it comes back...

 

[JamieMcC]

I have a pair of K75-40 100UF 1000V bath tub pulse capacitors which get used as coupling caps and have to connect them up externally when in use as they to big to go inside my amps case! They are bypassed with a Teflon the sound is utterly  beguiling yet feels highly resolving also, they are by far my favourite cap in this spot closely followed by the Epcos pio 100uf motor runs which are more neutral sounding.
 
The best analogy I could think of to describe these two pio caps influence over a standard dry film is its feels like your looking at something below the surface of the water without then with polarized sunglasses suddenly that surface glare vanishes allowing you to see deeper below the surface into the water/music objects become more 3D crisper and better defined with more substance to them.

 

[dimkasta]

Is there a reason why you are using such a big capacitance? I considered my 10uFs to be BIG!

 

[JamieMcC]

  Is there a reason why you are using such a big capacitance? I considered my 10uFs to be BIG!

 
I believe its due to the topology  being OutputTransformer-Less with a direct coupled circuit. (Bottlehead Crack kit) stock its comes with some electrolytic 100uf caps which are nice and small and easily fit. Swapping them out for films makes a worthwhile improvement but you start to run out of room real quick.

 

[dimkasta]

Ah it s inside an amp. I was thinking pre-amp to amp DC coupling.

 

[elmoe]

Has anyone ever tried these as output caps in a tube amp?
 
http://www.newark.com/panasonic/ezt-vkctyp1ha/cap-film-581uf-10-5-450v-smd/dp/28X5166?aa=true&min=810000020%2C810115803%2C811254861&max=810020382&categoryId=800000005277
 
581uF, 450V, 105°C max operating temp.
 
Far from cheap but it looks like they could do a nice job?

 

[JamieMcC]

  Has anyone ever tried these as output caps in a tube amp?
 
http://www.newark.com/panasonic/ezt-vkctyp1ha/cap-film-581uf-10-5-450v-smd/dp/28X5166?aa=true&min=810000020%2C810115803%2C811254861&max=810020382&categoryId=800000005277
 
581uF, 450V, 105°C max operating temp.
 
Far from cheap but it looks like they could do a nice job?

Ouch they are pricey
 
I would rather just parallel up some 200uf capacitors the ones in the ebay link below reportedly work very well with audio and at a fraction of the price if you are US based.  I tried to order some to try out but delivery to the UK was $60! for 3 plus another $30 for the ebay Global seller import program cough cough (ransom fee) which was a shame so I left them. The postage and fees made the price only a few dollars less than buying new Epcos 200uf's pio from Farnell.
 
http://www.ebay.co.uk/itm/ICAR-LNF-P3B-200-30-CAPACITOR-200uF-10-Un-420V-Urms-300VAC-420VDC-/230968898220?pt=LH_DefaultDomain_0&hash=item35c6d1b2ac
 
http://uk.farnell.com/epcos/b32361b2207j50/cap-film-200uf-250v-screw/dp/2219192
 
The Epcos 100uf have proved to be nice sounding caps in my set up the stud and nut end connections make it super easy to roll in and try out different bypass caps 

 

[elmoe]

 
Ouch they are pricey
 
I would rather just parallel up some 200uf capacitors the ones in the ebay link below reportedly work very well with audio and at a fraction of the price if you are US based.  I tried to order some to try out but delivery to the UK was $60! for 3 plus another $30 for the ebay Global seller import program cough cough (ransom fee) which was a shame so I left them. The postage and fees made the price only a few dollars less than buying new Epcos 200uf's pio from Farnell.
 
http://www.ebay.co.uk/itm/ICAR-LNF-P3B-200-30-CAPACITOR-200uF-10-Un-420V-Urms-300VAC-420VDC-/230968898220?pt=LH_DefaultDomain_0&hash=item35c6d1b2ac
 
http://uk.farnell.com/epcos/b32361b2207j50/cap-film-200uf-250v-screw/dp/2219192
 
The Epcos 100uf have proved to be nice sounding caps in my set up the stud and nut end connections make it super easy to roll in and try out different bypass caps 

 
Yeah they are too expensive for me, was just curious if anyone ever gave them a go. The ICAR could do but I would like a minimum of 400uF / channel @ a minimum of 400V so the Epcos are no good for what I need.

 

[dimkasta]

The lack of bass was something that did not seem to go away with breaking in, so I decided to add another K75-20 in parallel.
So now per channel I have
 
2 x 4.7uF K75-10
1x 0.1uF FT-3
1x 1nF SGM
 
All in parallel. The interconnect goes to one 4.7uF and all others are connected in star style with thick 1.5mm copper wire (middle of the star is the main cap)
 
At last the last octave is back.... I need ~10uF after all for my 22K impedance monoblocks...
And as a nice bonus, there seems to be a very distinct improvement on the mid-highs as well... More airy if you need an audio-phool word
Plus everything is more focused now and the stage is huge once more... It kind of reminds me what I had with just 0.47uF FT3s on my 220K amp.
 
Let's see how this one goes for a week or so...

 

[pelopidas]

Hey dimkasta
 
I am also currently playing around with K75-10 2.2uf and now the K73-16.
Before the K75 I was using Daytons which sounded very clear and detailed but were just missing that lovely "je ne sais quoi" .  I first put in the K75 and wow they are dark when new compared to the Daytons. Voices sound beautiful but there is a lack of detail I was struggling with. I put a Vishay 1837 0.01uf on there and got some top end clarity but still not that amazing sound-stage I had with those cheap little Daytons. Then I added a 0.1uf K72 teflon and Ugh! what a mess. I gave them about 20 hours but then took them out again and put them on my burner to let them bake a while. The weirdest thing is the K72-P6 have such microphony. I can hear the frequency sweeps loud and clear coming from the caps. So while this combo is cooking I decided to put in the K73-16 that were just sitting here while i was futzing around the with the huge k75 and k72s. It is a small cap not much bigger than a Dayton but my system is alive again. Totally reborn. The dynamics are just fantastic. There is depth in the sound-stage that just was not there with the K75-10.  I am going to listen to this for a while and see how burn in changes these guys. As a side note, within 5 minutes of first hearing these I went on ebay to order more, thats how good they sound in my configuration right now. I usually bypass everything with the 1837 because I have not had any negative experience with it yet and it always opens the sound up. So far with the K73 I have not had the desire to do that. The bass is tight, the highs are clear but most of all are the dynamics that have me listening to music and loving it in a way that I wasn't with the K75. It also sounds great at low volumes which the K75 really didn't.
FYI, I am using these as input caps on my T-amp.