X-24K DAC Mods - HELP!!!!

[jezza]

I'm about to mod my dac following the threads previously posted, however i'm a little confused about the values of the film caps i want to replace with polypropelene caps. The stamp on the existing film caps are as follows:
182J
222J
272J
392J
Using a little logic from modding my other MF kit I take it that these values equate to:
180pf
220pf
270pf
390pf
If i'm incorrect please let me know!
The problem is finding polyprop caps of the same values.
What values should I use if I can't source exact values?
Any help would be appreciated.

[Deleted]

Feb 25, 2009 21:44:03 GMT jezza said:

I'm about to mod my dac following the threads previously posted, however i'm a little confused about the values of the film caps i want to replace with polypropelene caps. The stamp on the existing film caps are as follows:
182J
222J
272J
392J
Using a little logic from modding my other MF kit I take it that these values equate to:
180pf
220pf
270pf
390pf
If i'm incorrect please let me know!
The problem is finding polyprop caps of the same values.
What values should I use if I can't source exact values?
Any help would be appreciated.

jezza
The "2" in 182 , indicates 2 Zeroes . i.e. 1800pF OR 1.8nF


From Jaycar Primer. www.jaycar.com.au/images_uploaded/rescode.pdf


Plastic film, Ceramic & Monolithic Capacitors
Most of these types have their nominal value either printed
directly on them or use the ‘EIA’ coding system, which
is a bit like resistor colour coding, but in digits: the first
two digits followed by a ‘multiplier’ showing the number of
zeroes. With this code the value is generally given in
picofarads (pF), which you’ll need to divide by either one
million or one thousand (respectively) if you want the value
in microfarads (mF) or nanofarads (nF).
Hence a capacitor marked ‘104’ has a value of 10 with 4
zeroes after it, or 100,000pF (which is the same as 100nF,
or 0.1mF). Similarly ‘681’ means 68 with a single zero, or
680pF, while ‘472’ means 47 with two zeroes, or 4700pF
(which is the same as 4.7nF).
SandyK

P.S.
If you can't source the exact values, my advice would be to leave the existing ones there. You could parallel a couple of capacitors to get the correct value, but in my experience, the result isn't as good as a single capacitor of the correct value.

[matt7941]

Good evening Jezza.

I just thought I'd chip in with my thoughts on the X-24K mods. To use a phrase commonly used here the mods I found gave best "bang for the buck" were:

1. Replace the horrible large Jamicon caps in the power supply with Panasonic FMs. The associated smaller caps (10uf 16v tantalums if memory serves me right are worthwhile replacing with Panasonic FCs or FMs, or if the budget stretches Elna Silmics or Cerafines.) This is a great improvement on its own.

2. Remove the dreaded NE5532 opamps from the output stages and solder in some dip sockets and try the opa2134s and opa2604s. They appear to be ok without bypassing and are certainly a huge upgrade over the NE5532s. The LM4562s seem to require bypasses but are worth the effort if you can do it but is a lot more effort.

3. Recap the small value ceramics with Evox-Rifa or Wima Polypropylene or polyesters. Also recap the tantalums on the on the upper board with Elna or Oscons in the digital side and Rubycon ZLs or similar quality in the Analogue stage. This seems to remove a good deal of the "nasality" from the sound and opens up the soundstage.

4. Replace the horrible output capacitors with some decent, slightly larger, non-polars such as Nichicon Muse (220uf 16v is good) or the 470uf Suntans. This seems to take the bass deeper and just lets more of the music through. If you can it also seems to benefit from installing parallel 1uf audio caps such as Mundorf MKPs or Auricaps (or similar). It just helps smooth the treble.

5. Replace the signal wire between the RCA outputs and the upper board with some solid silver 0.5mm teflon insulated.

I went to town a little on mine and some of the mods I undertook only brought very minor improvements. The caps listed above shouldn't cost too much and the opamps are relatively inexpensive. The silver wire is about £10 p/m but is an improvement.

If you want my opinions on the improvements PM me. I may also have one or two of the bits you need such as some of the smaller value caps which you could have. One or two of the caps in the output stage (the small value polyesters) I replaced with values almost the same but ever so slightly different.

Cheers

Matt

[jezza]

Thanks chaps! will do just that. Whilst trawling the net for answers to my original question found this cap calculator!!
www.muzique.com/schem/caps.htm
OK for newbie modifiers like me!