What are ideal caps(make and values) for my original MK-121 interfaces? Not looking to go too crazy on the prices, but want an improvement over the stock ones. Any direct links would be very helpful! Also, are upgrading the binding posts a sonic improvement?
I doubt very much that replacing the binding posts will result in a sonic improvement. At best, any improvement will be very subtle. However, you may gain some improvement in reliability. Depending on what type of termination you have on your speaker cables, better binding posts may yield a more secure electrical connection. The original binding posts were not the best in terms of dealing with today’s ‘garden-hose ‘ speaker cables and their corresponding mega-terminals.
If you are doing the C-Mod, as discussed in your previous post, I would definitely recommend using a 47-50 uF polypropylene capacitor instead of the nonpolar 47-uF electrolytic. Many brands are available: Solen is one of the more affordable ‘audiophile grade’ polypropylenes. I would recommend at least a 50-volt rating, but higher would be better. Be advised that, for a given capacitance value, polypropylenes are physically much larger than electrolytics, so a little creativity may be necessary to fit them into the space.
The two 0.01-uF capacitors on the PC board could be replaced with a better grade of polypropylene, but finding ones of the required 6000-volt rating will be difficult, and the price will leave you breathless. I would recommend leaving these alone unless one of them is defective.
The five small disc capacitors in the bias multiplier are not in the audio path, so a sonic improvement is unlikely. However, these have been known to go bad over time, so replacing them might make sense from a reliability standpoint. These should be replaced with a ceramic disc of the same capacitance value and voltage rating.
Thanks. I would also need to replace the 10uf cap. I assume something like the Solen would apply too?
Here's the same part listed on the Mouser-USA site.
FKP1Y021006F00KYSD WIMA | Mouser
Although this is a radial lead capacitor instead of an axial lead, and won't fit the spacing on the PC board, this is certainly a viable part to use in this application. You'd need to extend one or both leads to fit the board. And I like the price!
However, this should be considered an 'upgrade' only for very early interfaces that did not already have the yellow-jacketed polypropylenes that Acoustat used for later production models. If your interface has original polypropylenes, then this part should be used only for repair purposes, and in that case, all four capacitors should be replaced for the pair of speakers.
Hmmm...yes and no, and I should have explained this earlier. The intent of paralleling the original 47-uF electrolytic with a 10-uF polypropylene is to negate the poor performance of the electrolytic at higher frequencies. Ditto for further paralleling those capacitors with another small value of polystyrene capacitor (I forget what value was used, .01-uF maybe?).
So ultimately, you need approximately 57-uF of polypropylene capacitance in parallel with the small polystyrene. Any number of capacitors can be paralleled to reach that 57-uF, most typically using a 47 or 50 uF in parallel with a 10-uF. And yes, Solen would be a good source for both parts.
The polystyrene capacitor can be obtained from any number or sources, probably including Mouser mentioned above.
Any Polypropylene cap, made for audio or not (that includes caps made for SMPS supplies for example) will do wonders.
Take OUT the electrolytic, place in garbage.
The bypassing with a polystyrene, imo, is not required.
A small polypropylene, like 0.01 as a bypass is more than sufficient.
Polystyrene would be fine though...
Higher voltage rating is more better, generally speaking.
Paralleling several caps to make the nominal value is fine.
Older interfaces used 200ufd.
Use the value associated with ur interface, although some think that the lower
value cap there is a benefit anyhow. It is *not* a "crossover" in the usual sense, there is overlap between the two xfmrs (low & high) of several octaves, fyi.
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Take OUT the electrolytic, place in garbage.
The bypassing with a polystyrene, imo, is not required.
A small polypropylene, like 0.01 as a bypass is more than sufficient.
Polystyrene would be fine though...
Higher voltage rating is more better, generally speaking.
Paralleling several caps to make the nominal value is fine.
Older interfaces used 200ufd.
Use the value associated with ur interface, although some think that the lower
value cap there is a benefit anyhow. It is *not* a "crossover" in the usual sense, there is overlap between the two xfmrs (low & high) of several octaves, fyi.
_-_-
_-_-
I've bought upgrade/replacement parts fro my model 3 interfaces to bring them up to the "C" level. Here's my spreadsheet:
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