Testing capacitors.

pre65 · Post by **pre65** » Sun Dec 23, 2012 10:49 pm

I have three Russian 4uf PIO caps on the Pre project.

I would like to test the two used as coupling caps, is there a way of doing so with a DMM ?

If I use a DC supply then no voltage should pass, but if I use an AC supply then it should pass. Have I got that right ?

Mike H · Post by **Mike H** » Mon Dec 24, 2012 11:56 pm

If DMM is on AC Volts, yes. Really needs some sort of resistor as well on the output side as a 'load'.

IslandPink · Post by **IslandPink** » Mon Dec 31, 2012 3:44 pm

Would it be worth mentioning that a 4uF Russian paper in oil used as a coupling cap at pre-amp voltage levels could sound pretty poor ?
If you could go down to 1uF, you might get more music through .

pre65 · Post by **pre65** » Mon Dec 31, 2012 5:02 pm

IslandPink wrote:Would it be worth mentioning that a 4uF Russian paper in oil used as a coupling cap at pre-amp voltage levels could sound pretty poor ?
If you could go down to 1uF, you might get more music through .

I think Nick settled on 3.3uf as the cap value and those 4uf Russian MBGP-2 caps were the nearest I had in stock.

I'm thinking of some "monster" Russian K75-10 PIO hybrid caps (2.2uf) for the new preamp. The 500v (AC) ones are huge but the 250v (AC) ones are a bit smaller.

pre65 · Post by **pre65** » Mon Dec 31, 2012 5:15 pm

I could bypass them I suppose, I've just found a couple of Russian OCK73-16b 0.1uf 1600v caps in a box that Adrian (Buddam) gave me.

Post by **Nick** » Mon Dec 31, 2012 6:15 pm

pre65 wrote:
IslandPink wrote:Would it be worth mentioning that a 4uF Russian paper in oil used as a coupling cap at pre-amp voltage levels could sound pretty poor ?
If you could go down to 1uF, you might get more music through .
I think Nick settled on 3.3uf as the cap value and those 4uf Russian MBGP-2 caps were the nearest I had in stock.

I'm thinking of some "monster" Russian K75-10 PIO hybrid caps (2.2uf) for the new preamp. The 500v (AC) ones are huge but the 250v (AC) ones are a bit smaller.

I used 3u3 as I was unsure what it might drive. You should know, and can calculate accordingly.

Mike H · Post by **Mike H** » Mon Dec 31, 2012 6:53 pm

Phil, 2 x SA ClarityCaps 3.3uF from HFC won't cost a fortune. (Nick used the ESA's versions, do cost more)

Didn't realise or forgot you were using Russian PIO's, might in some way explain why it hasn't been sounding too good to date

Post by **Nick** » Mon Dec 31, 2012 9:29 pm

Mike H wrote:Phil, 2 x SA ClarityCaps 3.3uF from HFC won't cost a fortune. (Nick used the ESA's versions, do cost more)

Didn't realise or forgot you were using Russian PIO's, might in some way explain why it hasn't been sounding too good to date

I used MR, not ESA

pre65 · Post by **pre65** » Tue Jan 01, 2013 2:39 am

I'll have a look in my boxes of capacitors and see what I can find.

pre65 · Post by **pre65** » Tue Jan 01, 2013 4:50 am

I could not sleep, so I've been reading MJ, and although there is no formula, he suggests that for connecting to a "typical" valve amp a cap greater than 470nf (0.47uf), so looking through my box I have got a couple of 680nf (0.68uf) Clarity cap SA.

So Marks suggestion of 1uf was about right. Thanks for the tip Mark and to Nick for making me think about the value.

I'll try it later.

Post by **Nick** » Tue Jan 01, 2013 10:50 am

pre65 wrote:I could not sleep, so I've been reading MJ, and although there is no formula, he suggests that for connecting to a "typical" valve amp a cap greater than 470nf (0.47uf), so looking through my box I have got a couple of 680nf (0.68uf) Clarity cap SA.

So Marks suggestion of 1uf was about right. Thanks for the tip Mark and to Nick for making me think about the value.

I'll try it later.

Its just a CR high pass filter between the C of the coupling cap and the R of the following load. Don't know what edition of MJ you have, but I will put my own money on the fact that it contains

f = 1 / ( 2 * pi * c * r )

pre65 · Post by **pre65** » Tue Jan 01, 2013 11:01 am

It's probably in there somewhere.

I was reading in the preamp section.

Soldering iron is awaiting me.

Mike H · Post by **Mike H** » Tue Jan 01, 2013 1:17 pm

Nick wrote:I used MR, not ESA

So you did, my bad

Memory is crap

pre65 · Post by **pre65** » Tue Jan 01, 2013 1:22 pm

Think yourself lucky Mike, all I seem to remember IS shit.

(only joking

)

Mike H · Post by **Mike H** » Tue Jan 01, 2013 1:23 pm

Ah what confused me is I got ESA versions for my speaker impedance networks

audio-talk

Testing capacitors.

#1 Testing capacitors.

#2

#3

#4

#5

#6

#7

#8

#9

#10

#11

#12

#13

#14

#15