[JoshK]

By popular request, this thread will be stickied in the lab.

[JoshK]

You know, I had never noticed this thread before it was requested to be moved to the lab.  I usually view the AC forum under the favorites view, which has been selected for the circles I tend to follow most.  That meant I had never seen this thread.

I haven't yet read through it all.  I just read Jon L's first few posts on page 1, the ones with the meat.

I have a couple of minor points to make about the K72 teflon cap, in case it wasn't already made in the other 12 pages.  I have 4 .47uf K72s in my possession and I have quite a number of .1ufs.  So yes, they do come in larger sizes, it may be though that they were already picked over by the DIY crowd who refuses to pay the prices for some of the mundorfs, v-caps, etc of the world.  They have long been a cult favorite of the diy crowd.

Second, l actually cut the case off some K72s this weekend (before I saw this thread).  There are a number of threads on the diy forums about doing this and the improvement it is said to make.  I wanted to see how hard it was to do.  The easiest way is to use a set of plumbers pipe cutters. 

As noted by Jon, they have a solid post out of the cap.  The leads are internally wrapped around this post.  When you take the case off and slide the end caps off you will unviel the leads wrapped around the post.  The leads are about 1.5-2" long.  The case is most definitely steel as it was very attracted to my compression drivers that were getting de-screened too. 

I have to imagine the steel case does no favors for this cap.  Its going to interact with the electromagnetic field of the cap, but maybe the purpose these were made for needed the sheilding it provided.

I haven't ventured to recase them like some others have shown on the internet.  I am still looking for the appropriate sized cardboard cylinder to house them.  I could also use shrink wrap.

One thing I did notice is that the caps are trimmed to be the right value.  On occasion a small piece of the foil is added to the last layers, presumably to bring the cap up to the value specified. 

[JoshK]

I recently used the Russian teflons ....I then tried them as a bypass on the mid/bass driver. Forward sounding, lack of texture, loss of image detail ... not good at all. The whole speaker balance shifted upward and the imaging and soundstaging suffered badly.

...Enjoy,
Bob

Were they K72s?  If so, did you leave the case on them?  Were they anywhere close to inductors?  Something to think about.

[Jon L]

As noted by Jon, they have a solid post out of the cap.  The leads are internally wrapped around this post.  When you take the case off and slide the end caps off you will unviel the leads wrapped around the post.  The leads are about 1.5-2" long.  The case is most definitely steel as it was very attracted to my compression drivers that were getting de-screened too. 

What, after all that work, no internal photos?  

It's funny you mention K72's b/c I've been looking at it more lately. It's the the cap that seems to be the stepchild in the teflon world.  The liquid-teflon injected K72's were one way to go, but the more I think about it, my gut feeling is bypassing it with a small polystyrene cap, esp NOS TRW, would give me the smooth "airy" extension on top while diverting attention away from the hardish upper-mids.  This will definitely be on my to-do list.  

Thanks for the sticky BTW...

[JoshK]

I still have all the parts, so I will take some photos.  I cut the case off the .033uf (for phono RIAA eq) first and they were a bitch.  The .1ufs weren't as hard, probably because they were bigger and I was using the bigger pipe cutters.

I could loan you a pair of de-cased K72s if you curiousity would inspire you to try them.  You'd have to tell me which value (I have a cabinet full of them in various values).  I also have as many K40Ys and K75s (these are more for PSU, but worth a shot).

I also have a pair of Obbligato .47ufs.  I have a bunch of other more "bargain" caps as well.  I you want to add any to the round up I'll send them out to you.

[kyrill]

nice

this is a good and unexpected development

[BillB]

Anyone just try grounding the case?

[JoshK]

Have not, but it would still react with the field, maybe in a good way, maybe not.  Some have suggested that caps have a hysterisis property, don't know how a steel case would interact with that.

[JoshK]

Pics as requested.

The various pieces... (nevermind the cat hair, cat's blanket served as backdrop)


close up


I forgot to put the teflon "washers" in the pic.  They are on the ends to insulate the raw ends from the case.  The one end has been cut up a bit to get the washers out.  I kept the washers as they will be used when the new case goes on. 

[kyrill]

is that an expensive piece of "cutter" ? and how is it called?
kyrill

[Don_S]

is that an expensive piece of "cutter" ? and how is it called?
kyrill

Looks like your standard, every-day tubing cutter for soft metals like aluminum and copper.  Available at any hardware store for probably less than $20.  I guess more like $12-15.  It has been a few decades since I bought mine so my estimate may be off.

Of course the audiophile version has an oxygen free cutting wheel (proprietary alloy composition) and is cryo treated for $575.  Take your pick.

[toobluvr]

Yeah....
It sounds better as it cuts through the cap!

 

[dweekie]

..but *I* think AN or Jensen will be where you end up.

Until AN/Jensen becomes more affordable, esp the silver versions, there is an interesting capacitor company called AmpOhm from U.K.

I just started listening to their tin foil PIO cap (much larger than the same-value Mundorf SIO in the photo), and it's sounding very promising so far.  Even better news is these things go for $15-16 a piece...

Very nice, I was really looking at this cap but didn't feel like ordering from the UK.  The tin foil makes it very attractive, and being in oil makes it even more attractive to me.  I'm looking forward to your impressions.

[dweekie]

Pics as requested.

The various pieces... (nevermind the cat hair, cat's blanket served as backdrop)


close up


I forgot to put the teflon "washers" in the pic.  They are on the ends to insulate the raw ends from the case.  The one end has been cut up a bit to get the washers out.  I kept the washers as they will be used when the new case goes on. 

I use the nude FT3 caps.  Instead of the thin wire in your picture, two 1/4" or so aluminum foil leads protrude from both sides.  It is bolted to the ends (aluminum doesn't solder).  For my "re-case", I wrapped the cap with stretchable packaging tape, which I believe is a better dielectric than shrink tube or pvc pipes that others have used.  I cut holes in the foil leads and used a brass nut and screw to attach wire to it.  It's not elegant, but it works. 

[Jon L]

Very nice, I was really looking at this cap but didn't feel like ordering from the UK.  The tin foil makes it very attractive, and being in oil makes it even more attractive to me.  I'm looking forward to your impressions.

Actually, Thetubestore is the distributor of AmpOhm capacitors in U.S. and Canada.
http://thetubestore.com/paperinoil.html

I also happen to have the exact same cap but in aluminum PIO, so I can *really* compare tin to aluminum   I tell you.  These AmpOhm caps scream of quality and class the moment you hold them...

[jrebman]

John,

thetubestore seems to be out of stock on the tin pio caps -- at leas the values I need right now .

How long ago did you get yours?

Thanks,

Jim

[JoshK]

is that an expensive piece of "cutter" ? and how is it called?
kyrill

I think I paid $7 or $8 for it at Home Depot.  I have a few of them as I have done a lot of plumbing in my house.

[JoshK]

I use the nude FT3 caps.  Instead of the thin wire in your picture, two 1/4" or so aluminum foil leads protrude from both sides.  It is bolted to the ends (aluminum doesn't solder).  For my "re-case", I wrapped the cap with stretchable packaging tape, which I believe is a better dielectric than shrink tube or pvc pipes that others have used.  I cut holes in the foil leads and used a brass nut and screw to attach wire to it.  It's not elegant, but it works. 

Like the clear packaging tape?  I could try that.  Sounds easy. 

[dweekie]

I use the nude FT3 caps.  Instead of the thin wire in your picture, two 1/4" or so aluminum foil leads protrude from both sides.  It is bolted to the ends (aluminum doesn't solder).  For my "re-case", I wrapped the cap with stretchable packaging tape, which I believe is a better dielectric than shrink tube or pvc pipes that others have used.  I cut holes in the foil leads and used a brass nut and screw to attach wire to it.  It's not elegant, but it works. 

Like the clear packaging tape?  I could try that.  Sounds easy. 

Yes, but mine was the stretchable kind from 3M.  I thought it might hold tighter that way, but it probably doesn't matter considering the cap isn't rolled perfectly tight to begin with.  If you want to keep with the Teflon theme, there's always this shrink tube  (http://cableorganizer.com/heat-shrink/heat-shrink-PTFEdualwall.htm). 

[JoshK]

I used packing tape (knock off, not 3m).  I was going to use some epoxy to seal up the ends but noticed it said it was extremely flammable.  That won't work!     Got to find my glue gun.  I thought about silicone but the stuff I have on hand isn't liquid enough.