[Chipko]

Forgot to check the dimensions of caps I ordered for a crossfeed I'm building.

I've only finished the powersection of the amp so far. It's the universal powersupply from zero-distortion.com built on a bread board, something I've never done before. The tiny board next to the toroid is a 5V supply for 2 T-flipflops controlling source, xfeed and standby through relays (schematic). I'm using isolated inputs so I'm switching signal ground as well.

component side and solderside of the universal PSU.

 

[Voodoochile]

I hate it when that happens!
Nice job on the pad-per-hole PSU as well.

//ars secret handshake

 

[Nisbeth]

Chipko, if you want to use Wima Caps, you'll have to "downgrade" to the MKP-4 or MKP-10 series. (100 nF/250V max, 22nF/400V max).

/U.

 

[Chipko]

My supplier doesn't stock them until you get to 600V. Found some axial ones that I will use for the X-feed instead.

 

[stallion11msu]

I suppose you could always rig it up ghetto style...i.e. caps to wires to PCB.

 

[jeffreyj]

Quote:

Originally posted by stallion11msu I suppose you could always rig it up ghetto style...i.e. caps to wires to PCB.

You could, but that would introduce so much parasitic inductance that there would be little point in using caps like the Wima's shown in the picture. Of course, one could very well argue that there is little point in using high pulse power capable capacitors like those Wima's in the first place; after all, they were meant to be used as snubbers in switching power supplies, arc welders, etc. The physical size of the capacitor has a strong bearing on the amount of parasitic inductance present, so using one much larger than necessary does more harm than good.

 

[aos]

Quote:

You could, but that would introduce so much parasitic inductance that there would be little point in using caps

Is that true in audio range too? I wouldn't think it'd matter much to add an extra microhenry or ten. I myself used "ghetto" approach when I needed to use high quality bypass cap and had none, though it was experimental only. In fact some of the caps meant for speaker crossovers have a big body and a stretch of insulating wire coming out as leads which is nothing but "ghetto" approach (albeit by design). And for speaker crossovers they do need to be big because of large currents. I'd agree though for higher frequency stuff, if you're replacing your capacitors in digital section for "ultimate sound" and replacing ceramics with these, you're heading for a trouble.

 

[jeffreyj]

Quote:

Originally posted by aos Is that true in audio range too? I wouldn't think it'd matter much to add an extra microhenry or ten...

Does it really matter? Not at all, electrically speaking*, but financially speaking it's a big waste of money. A lot of the cost of snubber-rated capacitors goes into keeping the internal inductance down; connecting them to a PC board with leads pretty much nullifies the "advantage" the extra cost bought you.

*1uH at 10kHz equals 0.0628 ohms of inductive reactance; hardly worth worrying about.

 

[peranders]

Exactly as above! Don't use higher voltage rating than needed. Small is beautiful and good.

 

[jeffreyj]

Quote:

Originally posted by peranders Exactly as above! Don't use higher voltage rating than needed. Small is beautiful and good.

Oh, wow! I just noticed the voltage rating on those babies - 1000VDC?!?! That's nuts! People, peranders makes an excellent point here: small is good! And speaking of, peranders, weren't you doing some informal testing between surface mount PPS caps and through-hole polypropylene and polyester (Mylar) caps?? Any informal results to share?

 

[peranders]

The results is so far that polyfenylsulphide as input coupling cap works excellent but I haven't really tested between other types in this design. I just can confirm that it's alright to use this SMD cap. SMD polyester seemed a little simple.

Check for the white small thing at left.

 

[aos]

Be aware that higher voltage caps actually have better characteristics than lower voltage ones! I highly doubt it matters for audio but it's still there.

Most audiophile grade capacitors are HUGE so you don't have much choice anyway. If you want (metalized) polypropylene - and everyone sais it sounds better than polyesther - then you have to use big caps. If you have no space for big caps, then you have a choice of stacked film / mettalized polyesthers OR audiophile grade electrolytics.

Per-Anders, what value PPS caps are you using? I didn't know they exist in uF range (which you would typically need for input coupling). Are those C1 and C11 on your picture? That looks like 1812 size or something, 0.1uF.