Questions about original Cal Alpha DAC

I have and use both the Alpha and the Sigma II. With identical tubes in each they are sonically very close with the Alpha being slightly more 'detailed' and the Sigma being more rounded. The Delta is less sensitive to tube choices the Alpha much more so.

Neither of these are treated critically in my systems so I have stayed with new production tubes. If you don't like bright/cold/etched sound, don't buy Sovteks. I've used EI's for a very smooth sound and, for a fuller bass at the loss of the EI's smoothness in the mids and highs and with a bit of roll off in the highs as well, some EH's. If you've willing to spend the money on NOS tubes and you want a warmer sound, think Mullards (possibly some of the new 're-issues' which are purported to sound like Mullards ?).

The Cal Alpha/Delta IMHO can be one of most easy combo's to listen to over the long haul. You lose a bit of resolution, bass impact, and treble extension, but for the mid-range, especially with small groups, vocals and instrumentals, etc, it remains my favorite digital source.

Don't give up on it, just spend some time finding the tubes that will please your ear.

PS I forgot to mention mine is not the one with up-sampling, this could make a difference.

I've had very good luck with Sylvania 3-mica blackplate 5751s in the Alpha. They've become pricey, but the results have been worth it. Email me with your address and I'll send you a photocopy of the manual.

gentlemen: i own an alpha dac and delta transport. i too notice a bit of extra treble emphasis. i will give some ideas of how to deal with it but i also owned a sigma dac and heard the sigma 2.

i did not like the sigma because it was a bit lean. it is possible that the alpha has more treble energy than the sigma, but neither are smooth sounding and pleasant to listen to.

now for the solutions: line cords, interconnects, anti resonant devices and tubes.

lets start with tubes. my favorite 12 volt tube is a ge 5751 black plate. i use it in my other cd player, the audionote cd2.

next choice would be a 5814, perhaps raytheon red label or ge black plate. yes a 5814 is like a 12au7. you can use 12ax7, 12ay7, 12at7 and 12au7 with that dac. i have already tried a ge 5814. what i have in right now is an older (vintage unknown) tesla 12ax7. next i try to find cable which is slightly subtractive in the upper mids/lower treble. i like dcca for that purpose. finally line cord. this is tricky. i'm using sunny cable technology line cords on the dac and transport.

uh oh, i forgot the digital cable. i can't say too much here other than to recommend eoither the original illuminati single ended cable or the original ps audio x stream digital cable. i have no suggestions for xlr cable.

anti resonant devices which are soft help too--sound boosters, furniture foam or sorbethane will work well under dac and transport.

it is also possible that a transport other than the delta may be a help to offset the aforemntioned character of the dac.

i'm not done yet. i thought of one more tweak. use ers on the transport and on top of the power supply of the dac.

contact still points. they come in about 8 by 11 inch sheets for appropximately 22.00 .

i hope this helps.

after following all of my own suggestions i have ameliorated the problem to some degree, but i still prefer my audionote cd2.

Hello all again,
I'd like to make a correction, in that the prvious owner contacted me, and the tubes in this Alpha DAC, are currently the JAN-Phillips 5751.

I believe I have a pair, or two of virtually new Sovtek 12AX7AWPS lying around here.

They were bought to replace in the Sigma II, and an Eden World Tour 800 Bass Amp, and I actually preferred the chines tuve that came in the Sigma II versus the Sovtek WPS, as it seemed the Sovtek rolled off some of the high end, and the Stock Chinese Tube gave a bit more air at the top. Maybe the Sovtek 12AX7AWPS might have the same effect in the Alpha versus the Jan-Phillips 5751? Mark
Mark

Don't forget, digital cables (RCA, AES/EBU) and AC cords have a major impact on sound.

I had the Delta/Alpha for about 7 years, damped both chassis and special footers from
Steve Huntley, a Shunyata cord on each and a pair of NOS Mullards from Ken Chait @ Advantage Tube Services. http://www.tubeman.com