stereomour cap question

[balancedtriode]

hi i ordered a stereomour and i plan on upgrading some of the  capacitors to v-caps
which capacitors would upgrading make the most  difference to
and how many mfd`s are they
any info would be aprieciated
i would like to order them from v-cap before the kit arives thanks

[Paul Joppa]

The coupling cap is 0.1uF @ 630volts, and it is very significant.

The parafeed cap is 3.3uF @ 630volts - even if you could find a teflon cap that big, it would be huge and cost probably more than the amp. I (and many of us at Bottleheadquarters) like Auricaps, Grainger really likes his Obbligatos, and I've heard some good words for various Mundorfs.

Those are the two most important caps, sonically, to the best of my knowledge.

[Grainger49]

My Paramour (1s) use upgraded iron and 10uF@630V Obbligato Polypropylene film in Oil caps.  They are insanely inexpensive and tend toward a warm sound.  If you are considering V-Caps you have your sights set higher.  The Obbligato line includes two more expensive cap lines too but I haven't used them.  

I am also a fan of the USSR Military Surplus Teflon caps.  They do have 600V 0.1uF Teflon caps you can buy on ebay.  1.0uF is the largest they are available in.  So there is nothing to use as a Parafeed cap.

V-Cap has several, 3 or 4, different kinds of caps and they are well regarded.  

All such caps need a break in.  The better they are, the longer they take to break in.  So the V-Caps will take a while.  Look here for an easy way to break in them when you get them:

http://www.bottlehead.com/smf/index.php/topic,80.msg286.html#msg286

[shelby1420]

The coupling cap is 0.1uF @ 630volts, and it is very significant.

The parafeed cap is 3.3uF @ 630volts - even if you could find a teflon cap that big, it would be huge and cost probably more than the amp. I (and many of us at Bottleheadquarters) like Auricaps, Grainger really likes his Obbligatos, and I've heard some good words for various Mundorfs.

Those are the two most important caps, sonically, to the best of my knowledge.

Will 600v cut it??  I am considering either V-Cap Copper Foil and Teflon Film or V-Cap Tin Foil and Teflon Film, however both are only rated at 600vdc, is this ok??

[Paul Joppa]

Yes, 600v is OK.

[shelby1420]

Yes, 600v is OK.

Thanks Paul.

[shelby1420]

Paul or Doc, I seem to remember reading somewhere the optimal parafeed cap size would be different for either the 2AS version or the 45 version, is this correct?  If so is 2.7 more ideal for the parafeed cap and specifically the 2A3 version ( I plan on building the 2A3 version)

[Paul Joppa]

Parafeed caps can vary over a fairly wide range, with only modest differences in sound and technical performance. My calculated number comes from a bunch of simulations - it is not a theoretical optimization, but rather what looks like a reasonable compromise between various parameters. Those numbers are 2.5uF for 2A3 and 5uF for 45s.

In general, I'd say 1.5uF to 5uF for the 2A3 Stereomour, and 3 to 10uF for the 45 Stereomour. The stock values is 3.3uF.

[Grainger49]

I think that PJ has said elsewhere that the speakers react with the Parafeed cap.  So one that is tweaked to be optimum with a given speaker (I think that is done by ear) would be something other than optimum with a different pair of speaker.