[Inscrutable]

Guys,
Anyone also heard the Lite Dac?  I heard that in comparison to a Benchmark (which it bested) and a Cary 303/300 (which was marginally better).

[OrJazzM]

Hi all, I am new to the forum and this is my first post.  I recently purchased one Scotts' usb dacs, however this one is slightly different from his others as it has a jfet buffer.  My experience with dacs and such is limited so I would like to know if anyone else has bought one and can make a comparison to the tube version, thanks.

[kbuzz3]

Im considering the usb tube version for my office system.  Im concerned about accidentally leaving the dac on overnight-like when you have to run home and pick up the kiddies.  Can anyone comment on whether this would be a major problem?

I have no issue in buying new tubes and swapping them out.  I am more concerned with safety and overall relialbility if its left on once or twice or say over a weekend.

Thanks in advance for any comments. 

[boead]

It has NO off switch, Scott says to leave it on 24/7. Even a new tube will last years running 24/7.

[Hantra]

Im considering the usb tube version for my office system.  Im concerned about accidentally leaving the dac on overnight-like when you have to run home and pick up the kiddies.  Can anyone comment on whether this would be a major problem?

Hmm.  I have a TubeDAC that has been on for the past three years with the same tube.  Ohh wait. . . I did unplug it to take it to a friend's house for a weekend. 

 

[luvmusic8]

I was about to order Scott Nixon USBTD based on some of your views, until I come across  a negative review below, which gives it a failing rating of 2.25 out of 5. Can anyone comment on the review, and help clarify on any inaccuracies?
Thanks.

May 2006
Review By Dick Olsher
The Scott Nixon Audio Tube Dac+

Scott Nixon is best known for his line of affordable audio kits. The TubeDac+ is however only available fully assembled ($475). It ships with either a wall-mounted transformer or with the 3Xac 12VAC/3A toroidal power supply ($125.00 - less 10 percent when ordered with the TubeDac+), which is how my review sample was configured. The chip set consists of the Crystal CS8412 receiver and the Philips TDA1543 DAC. The output stage features a 6DJ8/6922 tube buffer, which lowers the output impedance and allows the Dac+ to mate with fairly low input impedance line stages and integrated amplifiers (>20 kOhm). There is also a passive "anti-sinc" filter that can be switched in and out. I assume that this corresponds to a first-order anti-imaging analog filter. Note that the unit inverts polarity. This, of course can be taken care of by simply reversing leads at the amplifier/speaker interface. But it would be very useful to have a means of inverting polarity on the fly so as to be able to check for best sounding polarity during playback. This is an issue with multi-track recordings, where the odds of correct polarity are only 50%. Matters are actually more complicated, because some tracks may be in phase, while others are out of phase. Thus, it usually pays to check for best sounding polarity setting album-by-album or even track-by-track.

Right out of the box, the TubeDac+ sounded significantly substandard. Even after an extended break-in, the sound was still so grainy and lifeless that I decided to return the unit to Scott Nixon for a checkup. Scott’s finding was that he DAC chip was clipping a bit and THD was well over 1 percent.  Apparently he has only had a handful of the chips do this, but usually within the first hour of burn in. The fix consisted of changing the fixed 'vref' resistor to a trim pot to precisely balance out the waveform.

Back from its visit to the doctor’s office, the TubeDac+ sounded much improved. Sonically, its calling card is a smooth, easy-to-listen-to presentation with a slightly romantic and prominent midrange. The residual level of midrange grain was a function of the type of 6922 used. Be sure to avoid any of the Sovtek variants. Siemens Gold pin and Bugle Boys worked best. Keep in mind that the buffer stage is operated at exceedingly low B+ voltage. That avoids the need for and the cost of a high-voltage supply, but the downside is that the operating point is constrained to a non-linear range of the transfer curve. It would appear that this design choice is responsible for most of the unit’s sonic shortcomings.

There were problems noted almost immediately at the frequency extremes. The upper octaves sounded closed-in lacking in air and finesse. That accounted for the fact that instrumental timbres sounded darker than the real thing. Bass lines were prominent but lacked adequate pitch definition. Soundstage dimensions were not fully fleshed out. In particular, the depth perspective was compressed. Image outlines were broad-brush, lacking the requisite specificity to resolve massed instruments. I preferred having the "anti-sinc" filter turned off, as it marginally improved image focus. Veiling of the soundstage-reduced transparency, which meant that visibility of the inner recesses of a recording’s ambient space was impaired. Neither was low-level detail resolution on par with the performance bar set by more expensive DACs. For example, it was difficult to follow instrumental lines backing a lead vocalist. Background harmonies were masked to the point of reducing the presentation’s clarity. And finally, dynamic shadings lacked conviction, as transients simply did not rev up as fast as they should.

Bottom line: Easy, inoffensive sound, trapped inside a low-resolution device.

Overall rating: 2.25 blue notes out of 5

[boead]

Some people like Haagen-Dazs and some like Ben and Jerry’s.

[boead]

This reviewer is speaking of the older TubeDA which is somewhat different. The USBTD doesn’t not have the phase or filter switch although it can be changed by Scott if you want.

I found that a BugleBoy or PQ gold pine wasn’t as good as the tube Scott ships. I called him and spoke to him about this and he agreed that the BB’s and PQ’s were not as good. I was surprised because I have always LOVED the PQ and BBoys in anything I own.

The reviewer also comments on what I perceive as something that is dull on the top end and not dynamic. Obviously the reviewer likes a bright and overly dynamic sound signature, something in which I detest! I guarantee that what this reviewer thinks is perfect would be like fingernails dragging across a chalkboard to me.

Lastly, this is a $475 tiny (failry portable) DAC. I have a feeling like the reviewer has to high an expectation and is quite possibly comparing it to a Highhend CDP or DAC.
I also have an Arcam FMJ23 with the dCS Ring converters as well as a Denon DVD-2900 in the same system hooked up to the same preamp. In direct comparison to each other the Arcam is way more refined and in control however the SN is in the same flavor as the Arcam with a warm, musical presentation. The Denon is analytical with a sharp edge, pronounced detail (low distortions ?) especially so with DVDA and SACD. It is by far the least musical of the three to me. But I’m sure the reviewer would like it best. To each his own.

BTW: I spoke to Scott yesterday (via email) and he said that the older USBTD can be changed to the new design he calls the USB.UFO.TD. “…The newer dacs use a constant current source under the tube.  If you need tighter bass and less distortion you dac can be up-fitted if desired.”


This is a different review:
http://www.audioreview.com/USBTDcrx.aspx

[Jon L]

The reviewer also comments on what I perceive as something that is dull on the top end and not dynamic. Obviously the reviewer likes a bright and overly dynamic sound signature,

LOL.  Dick Olsher can be called many things, but it is pretty well-known that Dick loves warm, rich, tubey type of sound, a bit too much so IMO...

[boead]

Really, well known? OK, but I've never heard of him before.

Oh well, I guess I’m not with the in-crowned. Whatareyougonnado? 


VivaLa Olsher! 

luvmusic8, Skip the SN and get what Dick recommends. What does he recommend? 

< being sarcastic >

[scottnixon]

The dac that ETM reviewed was a dud, it was broken as the dac chip proper was defective.  Sometimes it happens.  When I got it back it was dreadful.  I chose not to resubmit it as I felt it was just a bad deal all the way around. It was there for 9 months and I did one repair while DO had it, but did not fix the problem evidently and it should have been clear to the listener it wasn't at all right. But same listener also proclaims it inverted phase, which it did/does not.   I have learned also not to send product for consideration to sites that take ad banner monies from competitors. Besides who really cares about what anyone says about anything anyway  

[luvmusic8]

Anyone A/B compared Scott Nixon USBTD with another USB Dac Paradisea+ kind enough to share his experience? I am tryng to decide buy one or the other. Thanks.

[Dmason]

The new stuff looks very interesting...

Does anyone know the output V, and Z for the USB.Chibi.JFET ?

[scottnixon]

1.75v to 0db ref and about 100 ohms output z

[Dmason]

This is a good product! I am in for one. I will call.

[Zero]

You've got a PM, Scott.

[KT]

I have that older Tubedac+ that Mr. Olsher reviewed.

Based on extensive listening to my own unit, I'll say that Mr. Olsher's observations with his review unit don't correspond to the results I've achieved in my own system. So maybe Scott is correct that the review unit may have been substandard.

I'd say that the sound of the Tubedac+ is rich, natural, and involving. Very pleasant to listen to with a certain rightness to the sound. As it stands now, it's just really easy to get lost in the music without thinking too much about the sonic qualities of the dac or system, ie, wow, great rhythm and pace... great resolution... etc. Just listen to the music and be moved.

Having said that, I also have to say mine is not entirely stock. I did some experimentation with I/V resistors and series resistors and came up with some combination of Shinkoh tantalum, Riken, Caddock, and Vishay... can't remember what went where, but after I was done this is my favorite dac of the ones I own. Oh, and I ended up going with Blackgate N as the ouput caps.

My other DACs are DIY Paradise Monica II and Scott's earlier DacKit. Also very good DACs, but the TubeDac+ has more feeling to it - because of the tube, perhaps? It's a very luxurious sound without being mushy or slow.

If the IS2 input is sonically superior is SPDIF, then the USBTD should be that much better than what I described.

Best,
KT

 

[TomekZ]

Having been partial to Nixon made DACs for several years, I remember being surprised by the one negative review. Nixon DACs I've listened with over a long haul: tube DAC, then tube DAC+, then USB DAC, then USB tube DAC. Other Dacs that were nice but were less satisfying after a few weeks listen were a couple of Ack! Dack!, an Audio Mirror, a Charlize, & a Lite Ah. Note: all were non-oversampliers. All were nice in their own way, just not as right in the midrange. The only non-oversamplier that, to me is on par is the Promitheus. I've not heard the Altmann which is also so loved. Oddly, I've not heard an over or an over & up samplier.