New Improved TubeDac

el-cee · « **on:** 4 Dec 2003, 12:06 am »

According to Scott's website, new, assembled TubeDac now has sinc filters that can be switched in and out with outboard toggle switch. Also included is beefier, 4 amp desktop transformer. Price up to $400 for TubeDac and $475 for TubeDac+. I have one TubeDac on order, but pre-upgrade.

BeeBop · « **Reply #1 on:** 4 Dec 2003, 11:06 am »

Quote from: el-cee

sinc filters that can be switched in and out with outboard toggle switch

What do the sinc filters do? Does anyone know if the TubeDAC is still phase reversed?

JohnR · « **Reply #2 on:** 4 Dec 2003, 11:17 am »

The sinc filter corrects for the rolloff caused by the zero-order hold that is a necessary part of any DAC. Mathematically, sinc(x) = sin(pi*x)/pi*x, except that sinc(0)=1.

As for phase, have you ever heard any difference in absolute phase? Do you know the phase of every piece of equipment in you system? What about each driver in your loudspeakers?

I think people worry too much aboiut the wrong things....

BeeBop · « **Reply #3 on:** 4 Dec 2003, 02:19 pm »

Quote from: JohnR

As for phase, have you ever heard any difference in absolute phase? Do you know the phase of every piece of equipment in you system? What about each driver in your loudspeakers?

Well no I don't - in fact I don't know a heck of a lot about the whole thing at all (as you no doubt can tell). However, I am interested in an outboard DAC because I think it will improve the sound for redbook CDs, which are my primary interest and I have seen postings that say you should switch the phase on your speakers when the TubeDAC is in play and switch back when it's not - for example if you are watching a dvd movie, which seems a bit of a hassle.

Are you saying that's all BS?

Carlman · « **Reply #4 on:** 4 Dec 2003, 02:45 pm »

Quote from: JohnR

The sinc filter corrects for the rolloff caused by the zero-order hold that is a necessary part of any DAC. Mathematically, sinc(x) = sin(pi*x)/pi*x, except that sinc(0)=1.

As for phase, have you ever heard any difference in absolute phase? Do you know the phase of every piece of equipment in you system? What about each driver in your loudspeakers?

I think people worry too much aboiut the wrong things....

Thanks to Kris at 8th Nerve, I actually do know the polarity of my equipment.

What's more, I check every CD for phase by contacting the artist and recording studio and asking who mastered and produced the CD to find out who the engineers are. Then, I submit a 'phase request' to the recording engineer and they usually get back to me within a few months. Once I receive the 'phase certificate' I can switch my speaker cable polarity to the proper phase and listen to that CD.

Seriously, I really can't hear a huge difference if it's right or wrong but, I can hear the difference.

Back to the DAC.... John's explanation makes me think that SN may have fixed my only gripe with his DAC... to me, normal tubedac sound like the upper midrange and highs are farther back or... less pronounced/detailed than the lower midrange and lower frequencies. It's not rolled off at one point, but, starts rolling off in upper midrange gradually.

I may not be explaining my gripe well but, if this is fixed, and everything else stayed the same, I'll sell my DAC which I still think sounds better than anything else I've heard... to buy the SN.

BeeBop · « **Reply #5 on:** 4 Dec 2003, 03:07 pm »

Quote from: Carlman

What's more, I check every CD for phase by contacting the artist and recording studio and asking who mastered and produced the CD to find out who the engineers are. Then, I submit a 'phase request' to the recording engineer and they usually get back to me within a few months. Once I receive the 'phase certificate' I can switch my speaker cable polarity to the proper phase and listen to that CD.

Well you can see why I chose my avatar

Hantra · « **Reply #6 on:** 6 Dec 2003, 07:07 pm »

Bee:

To answer your question, yes. The new TubeDAC still does output inverted phase.

B

JohnR · « **Reply #7 on:** 7 Dec 2003, 09:16 am »

My experience with "absolute phase" is amusing (in hindsight...). I used to have a DAC with a phase switch, so I spent some time switching it back and forth attempting to discern a difference. Speakers, headphones, darned if I could tell any difference. It wasn't until months later, probably when I sold the DAC, that I realized that that DAC, having two sets of outputs, only had phase-reversal operating on the outputs that came "after" the beefy "class A" buffer amplifiers. I wasn't using those outputs because the unbuffered output sounded better! (Because it didn't go through the extra amplifiation stage.) Oh well, I've never been bothered to repeat the experiment ...

Quote from: BeeBop

Are you saying that's all BS?

No, I'm saying that it's a good idea to look at all the other factors. If, for example, you have a tube preamp, there's a very good chance that it *also* is inverting phase. This is just because of the way tube circuits work. Now, if you're as careful as Carlman here and have figured out that you have an odd number of phase reversals in your system between the bits on the CD and the speakers, then the solution is simple and absolutely free: reverse the speaker leads and now you have an even number, which is equivalent to none.

Never mind that your speakers are not transient perfect and the recording engineers don't care about phase, at least *you* got it right

Hope this helps

arthur · « **Reply #8 on:** 16 Dec 2003, 08:03 am »

i just received my TubeDac + after upgrading it to the new specificatons and adding the filter switch. Honestly, i didn't think that the upgrade would do much. Mostly, i was looking foreward to the switch so that i could bring down the highs a bit when listening to some of my very poorly recorded metal cd's.

All i have to say is

!!! The sound has noticably improved in every way AND i don't even want to defeat the filter for any of the recordings that originally annoyed me a bit! Granted, i've only had the dac back for 1 day, but this thing certainly does sound much better on Paganini, Mingus, AND Dissection! if you've heard the older version of this dac and were on the fence, than i would jump on the new version while the prices are so low.

the only thing that i'm wondering is if upgrading the power supply or the tube would make much audible difference... well, for now it does not matter - i'm VERY happy with the sound and truly grateful to Scott Nixon for such an awsome product at such an unexpectedly low price, for its caliber. In fact, in every one of my dealings with him, he has always exceeded my expectations when it came to quality, price, and service.

viggen · « **Reply #9 on:** 16 Dec 2003, 08:22 am »

arthur,

I have the dackit for 8 months now, and I just upgraded it with the external power supply, 3XDC. I too am overjoyed with the quality of sound I am getting from Scott's dac.

vpolineni · « **Reply #10 on:** 20 Dec 2003, 08:13 pm »

how do you place an order on the scott nixon website? Does he have a phone number? I couldn't find one on his website.

viggen · « **Reply #11 on:** 20 Dec 2003, 11:14 pm »

http://home.triad.rr.com/scottnixon/dac.htm

Here you go.

el-cee · « **Reply #12 on:** 20 Dec 2003, 11:15 pm »

email: dackit@triad.rr.com
or vox/fax: 336-884-7394

Carlos · « **Reply #13 on:** 21 Dec 2003, 04:06 am »

Part of the advantage of the 3XAC (aside from just being a better transformer than the desktop transformer) is the superior umbilicus that connects it to the DAC, and that it allows you to use aftermarket powecords.

Changing the tube makes a very big difference IME. IMO the stock tube is bottleneck in the DAC's performance.

MttBsh · « **Reply #14 on:** 22 Dec 2003, 01:53 am »

Carlos, what kind of tube do you use in the SN DAC to get such an improvement?

Thanks

Matt

Carlos · « **Reply #15 on:** 23 Dec 2003, 12:35 am »

Hi Matt,

Right now I'm just using a JJ E88CC. I also picked up an Electro-Harmonix 6922EH and a Ei Yugo "Ei Elite" 6DJ8, but haven't been tempted to try them yet. All of these are new production tubes, and most TubeDac owners seem to go for NOS Amperex tubes.

One other word on tuberolling: A lot of 6DJ8/E88CC/6922 tubes seem to be a bit microphonic. A tube damper from Herbie (or something similar) is a cheap fix.

MttBsh · « **Reply #16 on:** 23 Dec 2003, 03:25 am »

Thank you Carlos, I'll give the JJ E88CC a roll. I bought the extra power supply from Scott when I got his Tubedac +, and agree that this makes a major difference, especilally when using a good powercord (I use a Z Cable p/c). I also damped the inside of the DAC and Power Supply with Dynamat and applied some ERS cloth, and those seemed to improve sound a bit as well. I'll be anxious to see what the JJ tube does.

Thanks again for the info!

Matt

Carlos · « **Reply #17 on:** 23 Dec 2003, 03:56 am »

Hi Matt,

I should note that I just have the regular TubeDac and 3XAC, not the "+" version, so YMMV on which you like best in your system. Lots of options though in new and NOS tubes though.

If you try the JJ, I found the break-in was about 50 to 100 hours (actual play-time, not just on-time).

HChi · « **Reply #18 on:** 15 Mar 2004, 09:23 pm »

Is there any further finding/feedback about tube+ dac and its new 3xdc? What power cord and tubes are used with good result? I am torned to choose between ack! dack and tube+ dac w/ 3xdc. Thanks.

MikeCTM2 · « **Reply #19 on:** 15 Mar 2004, 09:52 pm »

would you believe i feel the exact same way HChi i'm really glad you asked this question if no answer, i'd say it's worth starting a new thread for.