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I repeat my question posted to the Amp Asylum:
I have (among others) a Chinese Image 34i integrated amplifier. It sounds pretty good - agile and dynamic, but sometimes tends to be bright. I attach two pics showing black shiny caps (.47uf MC-Caps looking like Mundorfs).
I am wondering whether I can upgrade the sound, in particular, cure some brightness if I replace the stock caps with .47uf/600V Vit-Q caps (if I find them) or at least Russian K40Y caps (I did not see 600V caps anywhere, though) or more expensive V-Caps?
Thanks for your thoughts.
Follow Ups:
You need to look a little closer in your own backyard.Most of us have bought our pio caps in your country or in the Baltic states. The k40y caps will help tremendously and you need a put a few carbon film or carbon resistors in..I can see where that amp would sound rather dry and brittle with all those metal film resistors and the caps may be metallized as well..Get these caps and then take out the resistors between pins 5 and 6 on each output tube and put in 1k carbon comps,or at the very least carbon films and I think that will solve much of your problems.You also should carbon film resistors on the plates of the drivers.
Honest amplification is better than excessive 2nd order distortion anytime.
Edits: 03/29/14 03/30/14
Mike,
I've found a local seller who offers 0.46uf/500V K42Y-2 instead of K40-Y9. Are they equally good?
Check operating points and consider whether you might need nicer output transformers.
This is most likely the cause
I received a letter from the manufacturer where he/she says that the stock CM-caps "just so-so" and said I can use any caps inclusing Solens which they also handle. I think I will try Russian PIO caps when I find them.
There may not much hope for this amp.
Edits: 03/28/14
I would agree with Tre, but you may not have the skill/knowledge to be able to make that assessment, or to fix anything you find wrong. Fortunately it is easy enough to find out if the K40Ys will help through experimentation: ($22, http://www.ebay.com/itm/RARE-0-47uF-630V-Matched-pairs-PIO-Capacitors-K40Y-9-Lot-of-2-NOS-/231000898989?pt=LH_DefaultDomain_0&hash=item35c8b9fdad)
Those black caps in your amp are labeled "MPT" so are probably polypropylene film, generally considered a "good" type of construction for an audio cap. But each input/amp/speaker combination has its own strengths and weaknesses. If you try the KY40s or other paper in oil types and it still sounds too bright for your tastes then you should probably look toward Tre's suggestion.
Follow up to my previous post...
If the actual voltage at those caps is 400vdc or less then the 400v K40Y caps become an option, and they are much more plentiful, cheaper, and smaller.
Also note that Mr. Samra says that the voltage ratings on the K40Y caps are extremely conservative, and that you could potentially run a cap with a lower voltage rating even if the actual voltage exceeds the rating. Again this is info is per somebody else. I have not verified it myself.
The manufacturer says 400V (not less!) is suitable. A local dealer offers K42Y-2 PIOs instead of K40-Y. Are they equally good?
Some people say they are as good. Some say better. Some say not as good. But what is "good" anyway? Since it only matters how they sound in YOUR circuit you really must try them and see what you think.
Brightness can sometimes be harmonic distortion.
Check the operating points of each and every stage making sure they are all operating in the most linear way possible.
Tre'
Have Fun and Enjoy the Music
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