Silver Mica Fix

[brightcity]

Hello, I recently built a Fix choosing the setting that seemed most appropriate with my speakers. I used Silver Mica caps and a mix of wirewound and metal film resistors.

The sound is very different from the polystyrene's used in the kit. There is more high frequency extension and faster response. The downside is the polystyrene's used in the original kit had a very warm sound. Also I wont be able to switch between settings as in the original fix.

 

[Paul Birkeland]

mix of wirewound

That's a garbage choice for the fix, they are much, much worse than what we provide in this specific application.

 

[brightcity]

Cool, I like the sound of wirewound resistors. The ones I am using are a low ppm and provide a larger surface area for conductions. Honestly, I think you may be right about the sonic characteristics but I like them for some reason.

Potted the device in urethane gel and put it in a cigar box.

 

[Paul Birkeland]

PPM is immaterial in a resistor dissipating nearly no heat.

 

[brightcity]

True, yet Mills wirewound is built using ayrton perry winding thus is non-inductive unlike thin film resistors which can only use non-inductive materials. Wirewound also uses a enameled resistive wire thus does not suffer from cross trench arcing found in laser or knife cut thin film resistors. Cross trench arcing can reduce effective resistance in the case of DC buildup or high voltages.

In all honesty wirewound do sound alittle drab in comparison to metal film.

 

[Paul Birkeland]

True, yet Mills wirewound is built using ayrton perry winding thus is non-inductive unlike thin film resistors which can only use non-inductive materials. Wirewound also uses a enameled resistive wire thus does not suffer from cross trench arcing found in laser or knife cut thin film resistors. Cross trench arcing can reduce effective resistance in the case of DC buildup or high voltages.

That's all well and good, but there's no high voltage or any DC in the Fix.  Hence my comment that they are about the worst possible choice.

You have very nicely quoted the marketing materials for that particular part though.

 

[brightcity]

Thanks, I completly agree. My preference still is with wirewounds, still trying to figure out why.

 

[4krow]

Would the mica caps be advisable? Seems that the caps that came with the Fix work very well, but I am always open to suggestions.

 

[brightcity]

More neutral with more high frequency extension. Personally my only problem was I could hear the switches vibrating with such a light chassis. Cant hear em on my Stereomour input selector.

Id bet using polystyrene caps would be great with their lushious midbass and bloom.

 

[Paul Birkeland]

Mica caps are wonderful in high frequency applications and are very tolerant to heat and high voltage(if you want to pot with epoxy, and you can't find potting epoxy, this is very helpful). Neither of these is particularly important in the Fix, but they do sound very good. They are also a good cap to use if you want your fix to be dug out of the ground in 2000 years and still be operational. They should work as long as the epoxy case stays in tact, which would be a very, very long time.

The big downside to silver mica caps is that they are pretty expensive. This is masked a little by how small the values are, but paying $3-4 for a 1000pF cap gets a little crazy if you have to buy more than one or two.

Silver mica caps are also available in far more values, which is critical at times when you might be addressing ringing in a push-pull amp by adding a cap across the feedback resistor, and you need a weird value that doesn't exist as a polystyrene.

 

[brightcity]

Thanks, they are expensive but its so strange how the human hearing gets used to something and then continues to like regardless of all the other choices.