nice

[grufti]

a couple of flaming resistors are hoping for relief from speedball, but other than that: nice!

so nice actually that i am thinking about a shunt supply for the b+.

any time that more harmonic detail appears in an organic way is time for celebration. great depth. thank you bh crew

[Jim R.]

Great to hear another satisfied customer.  Can you tell me what headphones andsource you are using?  Just curious.

How's the imaging?

Thanks,

Jim

[grufti]

Headphones right now are Sennheiser HD600. The source is a Benchmark DAC1 set to "Calibrated" playing through a Funk Tonstudiotechnik SAM-1c in order to go from balanced to to RCA, then into the Crack.

The Crack is standard except for: 1A Schurter IEC power entry with line filter, more robust RCA jacks, shielded cable from RCA's to pot, PEC 25K log taper pot, EPCOS 270uf 250V 105C capacitors in the power supply [because I wanted 105C capacitors instead of the 85C in the kit and those were the best fit], Teflon tubing on a few exposed wires, some resistors just clipped not soldered, CAT5 cable for the AC heaters, because it's already twisted.

Tubes are: Tesla ECC802S, Sylvania 7236.

All voltages are very close to spec ... and the music sounds really sweet. It is going to be my winter headphone amplifier: my rough guess is that with the Crack typically about 1% of the energy used actually drives the headphones.

[Paul Birkeland]

The temperature specification for capacitors like these is more a number that helps determine cap life.  If the Epcos caps have higher ESR than the Panasonics/Nichicons they are replacing, you could end up with a noisy amp.  (The only Epcos caps I found to those specifications were pretty inexpensive and not advertising any specifications)

This is a nice replacement with a 105c rating if you like: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P11628-ND

[grufti]

PB, longer cap life is exactly what I was after since the Crack does run fairly warm.

The Epcos caps weren't my first choice, but I had stuff that I needed from Mouser and I wasn't going to pay shipping for another order elsewhere. The distributors have never been as low on product as they are now, at least not as far as I can recall. Mouser had most high voltage Panasonics "on order".

The difference in ESR beteen the Epcos 270uf and the Panasonics TSED 220uf comes out to about 2dB in PSUD II.

The Epcos actually cost more at Mouser than the very nice Panasonic TSED do at Digikey for the same values. Explain that, if you can.

[Jim R.]

Grufty,

Sounds very nice indeed.  Thanks for the details on the gear and the build -- "nice" is a good descrition.

-- Jim

[Paul Birkeland]

Thanks for providing the source on those Epcos capacitors.  I'm not sure why Google didn't pickup Mouser.  Were you able to measure the ESR before you installed them, or did you find it elsewhere?  I didn't see anything in the datasheet...

[grufti]

Epcos only gives the max. ripple current at 120Hz in their datasheet on the web. I have no way of measuring ESR at 120Hz reliably.

What I did in the end was run PSUD II with 270uf and a very conservative 1.4 Ohm ESR for the Epcos compared to 220uf and 0.678 Ohm ESR for the Panasonic TSED. I actually ran the calculation for the Epcos caps with a whole range of ESR values from 0.6 Ohm to 1.4 Ohm and the result looked OK to me in each case.

I might still end up replacing the third/last capacitor with the largest value Panasonic TSED that is available in 22mm diameter. That is a 470uf cap with 0.317 Ohm ESR, quite possibly worthwhile.

[karl]

Grufti -

I noticed your comment that distributors seem short on product these days. Any idea as to why?

My father just handed me an Allied catalog a few days ago. Over 2000 pages!

Regards,

Karl

[Doc B.]

Grufti -

I noticed your comment that distributors seem short on product these days. Any idea as to why?

My father just handed me an Allied catalog a few days ago. Over 2000 pages!

Regards,

Karl

Sure, the bad economy. No one was ordering parts from the distributors, so they stopped ordering from the manufacturers. Now that the economy has picked up the distributors are betting caught flat footed. We are constantly seeing parts back ordered 6-8 weeks and digging around wherever we can to find substitutes.