[Syzygies]

I'm working through the Pimeta parts list. As I've said elsewhere, I'd love to fit into the Hammond J12 case using 12 rechargeable AAA cells in two RC battery packs. This limits my C2, C3 capacitors to 12.5 x 20 mm. A height of 25 mm won't fit.

Ok, if I drop back to 10 AAA cells I can use the 16V Black Gates stocked by Michael Percy Audio (until they run out): 220 uF FK Polarized for 4 x $8.50, or 330 uF Standard Polarized for 4 x $2.25. Nothing 25 V will fit.

If I could actually find Elna Silmic, their 25V 220 uF is 12.5 x 20 mm, nice. It appears that http://www.thlaudio.com/elnaitme.htm may sell these soon, let's hope, otherwise these are basically unobtainable in consumer quantities.

So I read various places that the Panasonic FC is actually prefered by some careful listeners to any of the above, and Tangent recommends them. The 25V 1000 uF, Panasonic part number EEUFC1E102, Digi-Key Part Number
P10278-ND, is 12.5 x 20 mm and costs 4 x $0.87.

Tangent writes in http://www.tangentsoft.net/audio/pimeta/pguide.html

Quote:

If you're looking at caps over 1000 uF you're probably compromising too much on quality; try looking for a line of capacitors that will let you trade some of that excess capacitance for higher quality

I feel like I'm missing something here. It appears that there's no practical way I can spend more than 87 cents on this part. Any recommendations?

 

[bg4533]

The 1000uF Panasonics are a good choice. I am building a few Pimetas and Mints with them right now.

I think $30 or so on BGs isn't worth it. Not to mention the lower voltage and less capacitance will probably hurt performance more than the BGs help.

 

[aeriyn]

Try 4x 220uF 25V Elna Cerafines... I believe they are shorter than 20mm.

 

[skyskraper]

im running the fc's in my current pimeta and i don't have any complaints. ive only used these caps in the pimeta though so i don't really have any other point of refference. my next pimeta i intend to try out the nichion muse series, i believe they are about the same size. have you considered trying the panasonic fm? you may want to check the size on those, they may be useable

 

[bg4533]

The Nichicon Muze KZ 220uF/25V would fit here. It is the top of the line Muse and is pretty cheap. Only $.47/each at Handmade

 

[Magsy]

I've ordered most of my parts but I'm still spec'ing out some bits for both a mint and pimeta..

How much voltage do we really need? It seems that I need more with the mint than the pimeta but I can't find answers for certain.

Does 18v sound much better than 9v in a mint?

Is 12v enuff for a pimeta? (I have a 12v sealed lead acid battery sitting around, 1.2ah..)

 

[Syzygies]

When one runs the numbers pricing a PIMETA, the resistors are a trivial component of the total cost. By all accounts one can hear the differences; trying to make prototype Etymotic 4p to 4s cables sure brought that point home to me; the RadioShack metal foils described as an acceptable CMoy part completely destroyed the magic in the Etys. Made me think.

The White Noise Audio catalog got me started reading about 0.1%, 15ppm Welwyn RC55Y resistors. The most convenient source I can find is in the U.K., http://uk.farnell.com/, but I've been buying books across the puddle for years, they do come.

The "eureka" moment for me was reading an argument that debunks the standard chestnut that we don't need 0.1% because only relative values matter, it's cheaper to carefully match values. The counter-argument is that in order to make such accurate resistors, one is forced to precision manufacturing techniques that minimize most causes of resistor noise.

On this same topic, my $50 multimeters aren't precise enough to match resistors carefully by simply looking at the "ohms" screen, and I don't want to spend $300 for this one application. Another argument for buying 0.1%? On the other hand, it seems that I could just build the mono amp "from hell", with alligator clips to hold the resistors for a simple voltage-divider power supply, and measure DC offset from the amp (twice, swapping the resistor pairs) to more accurately compare my resistors. There must be an easier way that's also more accurate, like making a number of voltage readings with different currents?