difference in cal sigma II dac with/without 24/96 upgrade?

[kuad]

does anyone have any knowledge of the difference between the units that have the upgrade to the 24/96 and those that do not? I read in another forum that the units WITHOUT the upgrade sounded more "analog-like".

thanks!

[kuad]

....

[markd51]

I own both the CAL Sigma II, and CAL Alpha DAC's, both non 24/96, and have heard likewise from others as well. Mark

[hatrack71]

Is it possible to get upgrades for the Cal Audio Labs Sigma tube DAC? I have one of the first ones and would love to put more updated technology in it. If so, do you have a link?

[kuad]

markd51 are you happy with the sound?

[markd51]

Originally Posted by hatrack71

Is it possible to get upgrades for the Cal Audio Labs Sigma tube DAC? I have one of the first ones and would love to put more updated technology in it. If so, do you have a link?

Yes, there are some companies that still do repair, and will as well mod these Units, taking them up a notch.

As far as I can recall, a company called Approved Audio still does repair, and sells parts on all CAL gear. Another company who I know used to do mods on CAL gear, such as DAC's, and Transports, was Great Northern Sound in MN.

I in fact own a modded CAL Delta Transport, which I bought from Richard Gray, of The Power Company Fame, which was modded by Great Northern Sound, which has all Blackgate Caps, High Speed Rectifiers, and Bybee AC Filtration. Mark

[markd51]

Originally Posted by kuad

markd51 are you happy with the sound?

Yes, My Sigma II, and Delta Transport i bought back in 1997 brand new, and the Sigma II is a very nice DAC, tough to beat for the money that they sell for today. Very nice sound, full, deep bass, sweet tone, clear highs, but not etchy,or digital sounding, smooth sound, nothing missing from top to bottom with this DAC.

In fact, in many ways, I like the sound of the Sigma II better than the Alpha. It seems to have better overall balance, and it's voltage output seemed better, the Alpha was always known to be a Unit, with very high output voltage, something like 4.0v, and this seems to make the unit hit my pre-amp quite hard. It was said, CAL used to provide resistors with the Alpha, that could be soldered in, to fine tune output voltage. This was not needed with the Sigma/Sigma II DACs.

I also have a modded Delta, and Alpha DAC, which is currently in my system.
The Sigma II I notice, as have others, is less sensitive to Tube rolling. You could put a cheap chinese tube in it, and it sounds just dynamite. Of course a better tube will help the sound.

The Alpha on the other hand, is much more sensitive to tube rolling. And I've heard some claim that the Alpha was harder on tubes. I still have the original chinese cheapo tube that came with my Sigma II new, and was never able to wear it out! Nary a problem with that DAC either for all these years, they were well built. Often I have thought of selling the Sigma II/Delta, but seem to keep it as a back-up, just in case the Alpha ever goes kaput.

I could again, live happily with the Sigma II in my system. Mark

[hatrack71]

Thanks markd51. I definitely would like 24 bit processing in the unit. It actually still sounds pretty good with the older bit rate but I imagine it will blow me away with the new upgrade.

[goldear]

The rumors about the 24/96 units sounding inferior to the older sigma-delta converter units is true. I ran a CAL Alpha for many years as my DAC. I loved it because it was the most analog sounding DAC I had heard back then. Then the 24/96 upgrade came out. I sent mine the the factory for the upgrades hoping to get even more of that sound that I loved. When it came back, I hated it.

Yes it did have a little better detail, but the "magic" of that particular unit was gone. The big wide & deep soundstage that I loved, became constricted, and flat. The lovely midrange it had, post upgrade sounded no better than a generic CD player that you might buy at freys. The highs were more detailed, but that was about the only improvement I could hear.

In short, after the 24/96 upgrade, CDs sounded crappy (just like they do with most CD players). I actually sent it back to have the work undone, and the people at the factory thought that I was nuts. But I did it anyways, and when I got my unit back, the magic returned to my CDs.

I often wonder if this poorly designed 24/96 upgrade was the reason why the company went under. I could find no reason to buy a CAL after the 24/96 upgrades since after they "upgraded" them, they sounded pretty-much the same as everybody else's CD players.

[Tedrick]

I'm so glad this thread came up. I purchased a Sigma II off A-gon a couple years back, and I've often wondered what I'd missed by not holding out for a model with the 24/96 upgrade. From the looks of it, "not much."

[markd51]

Originally Posted by Tedrick

I'm so glad this thread came up. I purchased a Sigma II off A-gon a couple years back, and I've often wondered what I'd missed by not holding out for a model with the 24/96 upgrade. From the looks of it, "not much."

Tedrick/All,
I would imagine the re-capping of such a unit with better Caps would net some sonic gains, but the realities are, would such a cost be worth it?

I've never done a Cap count on the Sigma II, and I would imagine if one had the skills to do it themselves, then the costs wouldn't be so high. Otherwise, to pay someone else to re-cap, with let's say Blackgates, or Hovlands, etc, the money spent might be better used to just swap in a better DAC?

That's the thing though, better may only be "different", and possible one might be happy with the changes, or maybe not so happy?

Again, Tube changes could probably net some gains, but will the cost of perhaps an NOS Tube be worth the improvements? At least in the Sigma II, there's only one Tube to swap.

Also, as a reminder, Tubes other than a 12AX7 can be used in this DAC, such as the 5751 as one example.

I know New Sensor is re-issuing a 5751 Tube for not much money, but never tried them yet. Mark

[kuad]

the one that is being delivered has the telefunken tube.

[Tedrick]

I've got a Mullard 12AX7 re-issue installed in mine. Much better than an Ei gold-pin I started out with. I wouldn't mind trying one of those new TJ Fullmusic tubes that Grant Audio is carrying...maybe early next year.

[Tedrick]

I've got the Mullard 12AX7 re-issue installed in mine. Much better than an Ei I started out with. I wouldn't mind trying one of those new TJ Fullmusic tubes that Grant Fidelity is carrying...maybe early next year.