[FrankCooter]

I recently built a simple 2 stage balanced OTL amp for the HD800. The amp is a 112a DHT voltage amplifier  directly connected to a paralleled 6BX7 cathode follower. Output impedance is about 100 ohms, which is fine for the 300 ohm HD800's. The output capacitor is currently a generic 70uf motor-run PIO.  For what it is, the amp sounds surprisingly good.  I'm interested in upgrading the output caps. Would like to keep the cost around $300.00. So I'm looking for a quad of film or PIO caps in the  50+ uf / 250V range. Any suggestions  from you cap guys?. Currently I'm considering Mundorf  M "tube caps" Obbligato film power supply caps, and perhaps the Obbligato gold signal caps. Also looking at some of the Russian military surplus stuff. Since the amp is DIY, space isn't an issue.  Any practical alternatives I've missed ?

 

[JamieMcC]

  I recently built a simple 2 stage balanced OTL amp for the HD800. The amp is a 112a DHT voltage amplifier  directly connected to a paralleled 6BX7 cathode follower. Output impedance is about 100 ohms, which is fine for the 300 ohm HD800's. The output capacitor is currently a generic 70uf motor-run PIO.  For what it is, the amp sounds surprisingly good.  I'm interested in upgrading the output caps. Would like to keep the cost around $300.00. So I'm looking for a quad of film or PIO caps in the  50+ uf / 250V range. Any suggestions  from you cap guys?. Currently I'm considering Mundorf  M "tube caps" Obbligato film power supply caps, and perhaps the Obbligato gold signal caps. Also looking at some of the Russian military surplus stuff. Since the amp is DIY, space isn't an issue.  Any practical alternatives I've missed ?

If you can run 160v have a think about trying the MBGO 30uf and Teflon bypass off of ebay they will most probably only set you back around $20ish for both channels. Personally I preferred then to a number of poly caps even some Mundorf Mcaps I tried.
 
http://www.ebay.co.uk/itm/30uF-160V-MBGO-2-Russian-Military-Paper-PIO-Capacitors-for-Audio-10pcs-/371240885814?pt=LH_DefaultDomain_0&hash=item566fae5e36
 

 

[Jasper9395]

  Currently I'm considering Mundorf  M "tube caps" Obbligato film power supply caps, and perhaps the Obbligato gold signal caps. Also looking at some of the Russian military surplus stuff. Since the amp is DIY, space isn't an issue.  Any practical alternatives I've missed ?

 
I cant think of any modern PIO caps that would satisfy your 50+ uf / 250V range. Are you sure you need 250v? There might be some Western Electric caps out there that do though. In any case I would go with NOS caps. There is actually a good chance that the motor runs you have in your amp now will out preform the caps your wanting to replace them with.
 
Although, like you, I am a bit of a skeptical empiricist I do think a grading scheme for caps is useful. Take a look at this extensive comparison of caps for example. Here the mundorf supreme scores a 10. From experience I can tell you that caps like the MBGO or MBGCH-1 will far out preform it. I mean leave it in the dust, really a cap like the mundorf supreme does not even interest me anymore. Objectively speaking MBGOs or MBGCH-1s are just more transparent, detailed, have better soundsgate, and are smoother Et cetera. I would love to compare some NOS caps to some top of the line modern caps some time like Jupiter or Duelund but they are just prohibitively expensive.
 
If you have 300 dollars to spend I would encourage experimentation. With that amount of money you can just go and buy some different NOS caps off eBay and experiment. Ultimately it is about finding the best combination of caps. If you do decide to go that route be sure to report back to us

.

 

[FrankCooter]

Thanks for the advice! You guys pretty much confirmed my suspicions about expensive boutique caps and saved me a nice chunk of change in the process.
 
I went ahead and ordered 10 of the Russian MBGO's. I will bypass them with the standard Russian military teflons. I can live with the 160V rating.
 
I'll post my impressions as soon as they arrive.
 
Any other cap suggestions or ideas about cathode followers in general are welcome.

 

[mcandmar]

K42-11: I picked these up out of curiosity as i cant find much info about them.   At first glance they looked like PETP K73's with a silver body and green center but they are actually a metal case, and apparently a metalized paper in oil construction.
 
I used them to replace a pair of ClarityCap ESA's and i have to say i am very surprised by them.  They have slightly less low end vs the ClarityCaps but they sound clearer and more transparent to me which is kind of ironic.  Either way not a bad cap for $2.85 each, only limitation is the 125v rating.
 

 

[Jasper9395]

Mcandmar, this looks like an interesting cap. They seem to be relatively compact which can be a good thing. I might have to buy a few of these to see how they sound.
 
The green centre and metal case is something a bunch of different Russian caps seem to share. The K71s also use it. The green stuff in the middle is an end cap which isolates the insides of the cap from the metal body and the outside.
 
Here is some info I dug up an ebay seller.
 
"These are similar to K42y2 with a bit better Tangent of angle of losses. The size/capacitance ratio isn't that good but that's a good news if you are willing to sacrifice a little room for extra quality. Sonically the capacitors are roughly the same grade as K40Y9 or K75-10."

 

[mcandmar]

Interesting, though i find them very different to the K75-10's. I found those to be very dark and lacking in the low end and high end. They are great if you just want midrange as they have a unique sound to them.  I used them for a while in a preamp, even tried bypassing them with K72's which helped the high end, but ultimately the lack of low end response is why i removed them.
 
I haven't tried the K40's in a signal path so cant comment on those.
 

 

[Jasper9395]

I think what the seller means is that the K75, K40 and K42 are of the same quality in terms of transparency and so on. Don't think he is saying their sonic characteristics are similar.

 

[Johan-71]

Hi does anyone know if there is any sonical differenses between K75-10 and K75-24 or is it only the voltage rating that's different?

Johan

 

[Jasper9395]

Take a look at this video the third designation refers to "the index number of the exact design type". Looks like they are just a slightly different variation of the same cap. It is probably just the voltage rating, caps with higher voltage ratings usually do sound a bit better.
 
While we are on the subject of Russian cap designation system I found the below classification. You can look up the original here it was linked on another site. Not sure where I found it originally.
 

 

[Johan-71]

Thanks for the link, I've heard the same about higher voltage rating. I'm using a K75-10 as decoupling now and waiting for K75-24 to try out. Just have to wait and listen for my self. Using a Audyn true copper as coupling cap with good results. It's very transparent in that position and at the same time I got some more body with The K75.
It's almost as addictive as tuberolling this "capsoldering",sometimes even better cause the nuances are bigger.

Johan

 

[Jasper9395]

Don't have much experience with tube rolling but yes, with caps you can really tune your system. It's good you have some modern caps for reference, it will be interesting to see how the Audyn True Copper caps stack up as they are highly regarded. What values are you working with? I might have some suggestions for caps to experiment with if your interested... In terms of transparency the MBGO-2, and MBGCH-1 caps which are also PIO should be better then the K75.
 
I like the term "capsoldering" BTW

 

 

[Johan-71]

I will pass by my post-office later today to pickup 2 pairs of MBGCH-1 0,22 uF that I bought from fleabay.
I must say that I appreciate the time we are living in, I layed in my bed a couple of days ago and read this thread in my phone. 5 min later I had ordered and payed for four caps from Romania, just like that. Today I got a text message in my phone and all I have to do is pick up my package.
Depending on the little wife I might head down to the mancave and do some capsoldering tonight.
I'm trying to get the lady into this but the interest is rather low...

 

[Jon L]

I'm trying to get the lady into this but the interest is rather low...

 

[richie037]

Most of you worries to much about caps, while they still have the standard ****ty audio input connectors... the one sealed in plastic and measure the emi around iside cables, effecting a lot... search for perfect matched couples and same value resistors. And remove the carbon potentiometers. , cheap or expensive, they all suck. Wire them yourself and the brands.... enough oem-film caps around, just like elco's. And if you use a lot of streaming, wireless gear, why even bother.
gr richard