CAL Alpha DAC: Stock vs. 24/96 upgrade


I recently purchased a used stock (I believe 18-bit) CAL Alpha Tube DAC. I'm considering the 24/96 upgrade. Those of you who are familiar with the sound of both, please weigh in. Also, tubes that you like with either version, what sound do they produce? My DAC came with the Eico/Mullard brand 12AX7/ECC83. Thank you in advance.
routeman21

Showing 4 responses by ckoffend

Routeman, I considered doing this myself as I had a Cal Alpha original DAC. The general feedback that I received on this same mod (about 15-18 months ago) was some liked it better modded and others didn't.

Overall though, the concensus was not to pay for the upgrade but instead to just buy the 24/96 version and see which you prefer. Sell the one you don't like more. The difference in value between these two DACs is only about $150 (then, 15-18 months ago), so based on this, it is more cost affective approach.

FWIW, I never got the 24/96. I eventually went with a Kora Hermes (which I loved). But that Cal Alpha is a great DAC, especially for the price! Be very careful when shipping that unit, you need to place a piece of foam on the transformer to support it. It has a tendency to crack at the connection point and then you have a couple hundred dollar repair.
Kevin, if you send in the alpha to the service company (Kevin there) will tell you to do this. Repairing these is a big part of his servicing of the Alphas.
Kevin, When you take the cover off of the Alpha, there is the large metal piece/part inside. This is the transformer and is noticeably the most heavy part in the case. It is tall, comes about 1" short of where the top cover would be if the cover were back on. You should use a piece of styrofoam or even better a softer foam. This should be thicker than the space between the top of the transformer and the cover when it is put back on. This piece will then compress with the cover installed and hold the transformer in place to prevent its heavy wait from receiving shipping impact. Since the cover slides on it is fairly easy to do this.

What is known to happen without this is during shipping the box and components takes some real impacts when it is being tossed around and dropped. Due to the weight of the transformer these impacts cause cracks or total breaks to occur at the contacts or base of the piece.

If you ship the piece, you should always do this, but you also need to let the buyer know to remove it before playing. Many people don't know to do this and this is why so many of these units have been sold in good working condition, only to arrive not working at all - no power. I will check my office computer to see if I have a photo of this.
Kevin, I did some checking at my office to see if I took a picture of the support for the transformer - all packaing pics, but not of the unit opened with the support. I early stated it was Kevin with Approved Audio, it was really Larry. This is what he wrote to me when I sent mine in (and by the way, the unit will power up and even seemed to lock onto the signal - just no output):

". . . prior to shipping, i suggest removing the screws from the cabinet (4 on bottom, 3 on rear,
3 on top front) and sliding back the cabinet. you will see a large black thing in the front left corner-this is the power transformer.
take some cardboard or something similar and place some pieces on top of the transformer so that when you slide the cover back on, the cover will press against the transformer holding it in place. cal used a transformer which is not screwed to the chassis, it is held by the solder connections and some glue between the transformer and the circuit board. if the box gets dropped just right, the transformer can break loose. this is not a good thing. it doesn't happen often, but i've seen a couple. i always do this when i return ship them, and haven't run into a problem. it's cheap insurance. box it up, insure it for $1000 and send it in. it's a great sounding dac, i use one in my system."