Thanks for the replies.
I don't know the type and value of the original cap - hopefully a ph302 owner will volunteer the information.
The input resistance of the my SP16 line stage is 50kohms.
Assuming the value of the substituted Multi-cap is correct - I was considering replacing with a 1uF 200V teflon cap, perhaps the Audience Aura T (they seem to get high praise and not quite as expensive as other teflon caps).
My other train of thought is to put it back to original (if I can find out what that is) - I assume Dennis Had would have tested various caps in that position and settled on his choice for a reason (hopefully because they sounded good). |
Hmm thanks for your thoughts Dover.
Seems that MIT RTX caps are well thought of and regarded as a nice step up from the PPMFX. Economical too.
The Cary certainly sounds ok with the current PPMFX caps, but my feeling is that its not uniformly transparent across the frequency range. The caps may have nothing to do with this of course, but I'm curious to hear what a couple of well regarded Teflon caps might do for the sound. These seem to be universally praised for their transparency. |
Well, I'm not sure which way to turn now...too many choices.
Maybe I'll steer clear of the expensive Teflon options and go for something in the middle ground.
In no particular order, looking here and elsewhere, these appear to be worthwhile trying and likely upgrade from Multicap PPMFX:
* Multicap RTX
* Clarity Cap MR
* Mundorf Mcap Silver/Oil
The cheapest option - RTX - would appear to be a 'safe' choice.
Dozens of other choices, but I fear my head might explode with the options.
Reb, found one of your posts elsewhere, is it your understanding that Cary use MIT PPMFX as stock parts - ie the caps in my PH302 may be stock for the Mk2 model? (The pic I was comparing my unit to on the Cary website appears to be a Mk1 model). |
Ok, I've ordered both the RTX and the Mundorf Silver/Oil - that way I can experiment and it won't cost me the earth.
Thanks for all the helpful input. |
Thanks for the tip Reb.
Do you suggest using the RTX as a bypass on just the PPMFX or trying it on the Mundorf as well?
Maybe I'll get a couple of extra .15uF RTX caps to try with my SP16. It uses ARC branded 1uF Relcaps (labelled PP3MF) at the output.
Ironically, I changed a few things around tonight and have the Cary sounding much more to my liking. When I put it in the system a week ago I sat it on top of the SP16 to make it easy to compare the phono stages. Just tonight I've moved the preamp down a shelf and Cary now rests directly on the top (granite) shelf of my rack. This allowed me to experiment with different footers etc. Currently I have some old (Shun Mook!) steel spiked ebony footers under the Cary and I'm getting a marvelously spacious and dimensional soundstage with much better focus and presence than when it was plonked on the SP16. Probably doesn't hurt that the components are now spaced well apart either.
The Cary is whipping the SP16's phono stage big time now - much more spacious, airy and harmonically complex.
Will still be fun to see what the different caps will bring to the sound. |
Hmm...Reb, the supplier I was buying the RTX from doesn't have 0.15uF listed, 0.10uF should be ok shouldn't it? Isn't the rule of thumb 1/10 main cap size?
They do have 0.22uF if you think that's more suited to bypass 1uF. |
Thanks again Reb, Dover and others. I'll post back how things turn out. |
Well I substituted the Mundorf silver/oil for the PPMFX caps - Wow, really nice improvement! The Mundorf's, with only 10-15 hours of play, are more transparent from top to bottom and have great extension and 'air' while offering more refinement. The Cary sounds gorgeous and seems to have gained more 'speed' and neutrality. Voices sound stellar. Best of all it sounds even more musically engaging. PH302 with Mundorf S/OFYI Reb, I never received a reply to my (email) order for the RTX caps. Perhaps I should have chosen a supplier with online sales(?). Anyway I'm more than happy with the Mundorf caps and I don't think I'd want to play with bypassing the PPMFX now. |
Dover, there is more of a gap than appears in the photo, about 4-5mm. I also stood the caps off the PCB - mainly because there is a resistor under their footprint.
Those 6SL7 tubes run really cool, hardly giving off any heat. The whole unit only uses 15W according to Cary (most of the heat seems to come from the 5AR4 rectifier tube). I doubt it gets much above ambient room temps inside the case. |
Reb, Dover, thanks for the concern. I had read about the Mundorf caps not liking heat, so I checked things out before mounting. I've given the caps a little tweak - the distance to the 6SL7 tubes is 4mm. As you noted the caps are opposite the brown tube bases, not the glass envelope, and they approach the round base on a tangent. I think that gives plenty of breathing room. If we were talking about a power tube in a hot amplifier chassis it might be different, but the envelopes on these tubes only run warm to touch. You can read the specs for the 6SL7 here. As you can see the plate dissipation for the tube is 1W max and the heater is using <2W - so <3W total per tube (most of which will dissipate from the glass envelope - which has substantially more area than say a similarly rated 12AX7, hence the lower glass temp I guess). The PH302 has a rather big case with plenty of breathing room and the case itself gets barely warm...and that's only above the 5AR4 rectifier tube. I don't believe this environment should pose any issue for any reasonably designed electronic component. FWIW, the PH302's PCB mounts onto shallow standoffs to the bottom of the chassis - definitly no room to mount a cap like this on the bottom of the PCB. Once again thanks for the input. |
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Reb, Dover - what type of cap would you suggest to replace the .22uF 600V cap (long silver one in the PSU)? - I'd need something with similar form factor due to proximity to the Mundorf and the electolytic on the left. Could a bypass be used here?
Likewise what would you suggest to replace the Solen caps? |
BTW, just for curiosity I'll run an experiment next weekend. I'm going to tape a temperature probe to the side of the Mundorf at the closest point to the tube. I'll monitor the temps periodically for 6-12hrs and see what sort of temp change I get. I'm betting it won't be big - probably close to the ambient change in the case - but we'll see. |
Interesting comments regarding the Mundorf S/O caps.
I'm not hearing the same inconsistency with dynamics in the Cary phono amp.
Perhaps the caps have degraded over time(?)
The Clarity MR caps are supposed to be very good - if I were not getting such superb sound with the Mundorfs, I might be tempted to try them.
FWIW, I did conduct the temp measurement experiment that I mentioned above.
Ambient temp was 20ºC.
My phono amp reached stasis after about 1.5hrs. - the temp measured at the cap surface (closest to the tube) was then 32ºC. The probe hanging in free space inside the phono amp case was 29-30ºC (a bit higher than I thought it would be, given the coolness of the exterior).
In any case, I don't think 2ºC is significant enough to warrant looking into heat shields etc.
I also removed the top cover to measure glass temp on the the 6SL7 - but as soon as the lid was removed all temps dropped and the glass only read 28-29ºC.
For comparison the (exposed) 6NIP driver valves in my power amp had a glass temp of 47ºC and the (exposed) 6550A power tubes had a glass temp of 72ºC(!).
The Cary phono amp offers a relatively benign environment for electronic components....if the Mundorf's can't survive here then, IMO, they probably don't belong in any active devices. |
Tom, my note on the temp experiment was meant to address Reb and Dover's concerns above - not meaning to draw any conclusion regarding your setup.
That said, I have read some reports where users have stated the Mundorf S/O sound has changed after extended use >300hrs - not necessarily related to heat. Who knows?
In any case I have heard nothing but good reports regarding teh Clarity MR caps, they were on my shortlist and something I may try in the future.
Cheers - Paul |
I debated about posting this as it may be of limited general interest, but thought it may be of use to owners of the Cary PH302.
Following Reb and Dover's advice above I finally got to swapping out the Cary Audio 1 oil cap in the PS of the 302. While I was satisfied with the sound of the Cary with the output caps substituted, it did have a softness on transients that wasn't entirely to my liking. The integrated phono of the ARC SP16 was superior in this regard.
I was curious about whether this cap (not directly in the signal path) would have much effect. Due to space requirements choice of substitution caps was somewhat limited. The Multicap PPFXS (polypropylene/tinfoil) I chose fit easily and had a fairly good rep for PSU use. I used the same value .22uF/600V, though the voltage rating is overkill in this application.
The improvement in sound (after run in) was beyond my expectations.
Transient reproduction is massively improved - but without etch or over-emphasis. The soundstage is more open and tranparent with instruments and performers much more lifelike and 'in the room'. The phono amp retains its engaging beauty but now has realistic attack and decay.
There doesn't seem to be any downside, but agressive recordings don't get the same 'massaging' as they did with the oil cap in place. I don't think there is any doubt that the Multicap produces the more accurate and realistic sound in my system though.
Thanks again to Reb and Dover for the heads up regarding this substitution.
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Yes (I think those PPFXS tin foil caps actually cost around $10).
And it was a much bigger improvement than changing the coupling caps to the Mundorf silver-oil.
Its baffling that a capacitor in the power supply could effect the sound so much. From the midrange up the sound is so much more realistic: more transparent/faster/cleaner. The oil cap dulls transients and softens/veils the sound.
NOTE: I've only heard the PS cap change with the Mundorf output caps - ie I didn't go back to assess the PS cap change on its own.
If you do some googling I think you'll find quite a few people don't like the Audio 1 oil caps for coupling duties either.
If they really cost $90, maybe I should put mine on ebay - that would pay for the Mundorfs! |
FWIW, I could have used the 400V PPFXS but decided to replace with a cap of the same spec. Overkill in my application.
Cary have offered the Audio 1 oil caps as an 'upgrade' for some time - I think it was even an option on the SLP98. Again, try Googling for some results - I think you'll find reports of the same type of signature mentioned above.
Unless you like artificially softened transients/veiling, I'd steer away from those caps - there are plenty of other (cheaper) options to experiment with. |
Ceph44, I don't have direct experience using the Audio 1 oil caps for coupling (though my impressions of the cap in a PS application seems to mirror those who have).
I'm sure they would be 'smooth' if that's what you're after - I was initially beguiled by the sound of the stock PH302.
However, if my experience is anything to go by, I'm guessing you'll eventually grow disatisfied with the sound because at the end of day it makes music sound less real. YMMV. |
06-21-11: Theaudiotweak
.....The MR is a much cleaner and more neutral cap in my particular device than was the S/O it replaced. The MR is much quieter yet insightful and more musical. The bass is smoother and more detailed and controlled. Vocal placement and outline is more defined but the biggest difference in these two caps are the dynamic contrasts. The Mundorf seems to have a staggering mind of its own. In the course of a recording I seemed to be grasping for the volume control wanting to turn it up or down depending on the sonic impulse. It was if I were waiting for someone to rap on the door or a drummer to knock over his cymbal all in the course of one recording. In contrast the MR is much more linear and stable in its tracking of the sudden impulses in the music line..it is not at all compressed. The staging on the MR is more defined and detailed almost with a three d affect all with no perception of phase shift or crawl.......Tom Tom, out of curiosity I tried the Clarity cap MR's - in both my SP16 preamp and the Cary PH302. I didn't have the quirky dynamics you report with the Mundorf SIO but other than that I pretty much agree with your assessment. I do find the Clarity caps more explosively dynamic than the Mundorfs as well as being more transparent, open and neutral. Soundstaging - width, depth, imaging, reproduction of space is no contest - Clarity caps all the way. I can't think of a single area where the SIO outperform the MR's but the former do exhibit a certain seductive liquidity that the Clarity caps don't have. However I much prefer the transparency and realism of the Clarity caps. The MR's also sound great - smooth, detailed and very open - from the start and even better after 10-20hrs - no long breakin required. I wouldn't have thought it previously, but the SIO sound a bit colored and opaque by comparison. Thanks for the heads-up. Cheers, Paul |
