Transport for DAC

Shadorne - I'm perhaps very lucky with this particular unit. I used more expensive and larger ALPS "Blue Velvet" pot with conductive plastic track and matching was worse than this tiny pot (Alpha I think).

Benchmark do not recommend to use the Volume pot at less than 9 oclock as it may cause slight channel imbalances when used at extremes (same goes for any volume pot actually) - I think I read a comment on Headfi.org by Elias Gwinn about this very topic.

Shadorne - Thank you - that's probably the case especially with my amp (class D). 0dB setting is OK - it gives full power at about 1 o'clock position of the volume knob. The problem comes when I listen very soft at night. Fortunately volume pot on my Benchmark works from zero with very good tracking - might be coincidence since it doesn't look expensive.

Kijanki & Shadorne -- Thanks very much for the good comments and info. I looked at the manuals and Benchmark's comparison chart for all three versions of the DAC1, and yes the USB and Preamp versions are the only ones with the "State-of-the-art LM4562 high-current op-amps." The USB version has that op-amp in the output stage only, while the preamp version uses it throughout the analog paths.

A result of that is the 1600 ohm output impedance of the DAC1 with the 10db pad enabled is reduced to 425 ohms in the other versions, although that is still much higher than for the other settings of the attenuation pads.

But I too am mystified as to why the 10db/1600 ohm position should have produced such poor results in Kijanki's setup.

Thanks again for the good information. In my own case, when I make my purchase (probably in a couple of months), I think the choice will come down to the DAC1-USB, or one of two all-in-one cdp's (now there's a way to eliminate transport-to-dac jitter :)), the Doge 6 (tubes), http://www.pacificvalve.us/DOGE6.html or the Sony SCD-XA5400ES, both of which are in the same general price class and have received a lot of excellent comments. It's not worth it to me to go above that price level because around 80% of my collection and my listening is vinyl.

Regards,
-- Al

My power amp (Rowland 102) has only XLR inputs
rated as 40k impedance. 9pF with 1600 ohms of output impedance makes
fc=11MHz. It has to be something else.

It has to be something else.

I agree 100% - which is why I asked. It does not make sense unless
something else is going on.

The only thing I can think of is ground loop or RF/EM pick up. If you raise the
output impedance of the source to 1600 Ohms then you are surely much
more susceptible to RF or ground loop effects if there is any imbalance to
ground anywhere in the circuit. As you lower the output impedance of the
source you will kill any ground loop or RF/EM signal versus the true signal.

The fact this translates to more dynamics sounds intuitively correct...basically
cleaner sound is likely to sound more dynamic with more
"blackness"...

Shadorne - I'm using XLR cable without adapters. The only gain adjustment with XLR is either 4 jumper settings or volume knob on the front (if you chose this mode).
I'm using volume control (no preamp).

My power amp (Rowland 102) has only XLR inputs rated as 40k impedance. 9pF with 1600 ohms of output impedance makes fc=11MHz. It has to be something else.

I would thing that I might compare different levels or "hearing things" but review I read claims the same and Benchmark lowered this output impedance with stronger output drivers and lower dividers in DAC1 USB. I will try to find link to this review.

I can hear a little livelier sound at 0dB than -20dB but -10dB is much worse and my 0.5m cable has total of only 6pF/ft x 1.5ft=9pF.

Are you using the calibrated output - bypassing the DAC1 volume control?

What you report strongly suggests that the device (power amp or preamp) that you are connecting the XLR outputs of the DAC1 to - this device has a rather low input impedance (much less than 20K). I'd check this angle out - many power amps have simple input attenuators (rather than variable gain) which may lower the power amp input impedance (depending on the power amp volume/trim settings and the design).

Also if you are using adaptors to take XLR from the DAC1 to RCA then be aware that pin 3 must be left to float or yo'll get distortion.

Shadorne -

"To me the greater the precision the more problems/anomalies you discover in your recording collection."

This is very true. I discovered big difference in recording quality with the Benchmark. I like its clarity but it took a while to get used to it. At first I had impression that something (some instruments?) must be missing. I even heard opinion that "sound blob" performance is more musical than "analytic" Benchmark's performance where you can distinguish individual instruments. Some like also a little THD to make sound "lively".

I hear people saying that all is subjective and if you like it it's better for you. It took me a while to really like Benchmark and I'm always ready (with my limited experience) to learn to listen.

Word of a warning - Benchmark is not a warm sounding DAC. According to John Siau it was meant to be neutral because warm sound (exaggerated even harmonics) sounds wonderful with voice or guitar but not with instruments that have more complex harmonic structure than simple overtones (like piano or percussion instruments)

Interesting comment. FWIW I noticed an improvement in percussion and piano with the DAC1 versus standard low end Sony CDP. Vocals also sounded thinner and more articulate with the DAC1.

I prefered the more natural sound of the DAC1 (more natural to my ears - especially for cymbals and piano) but a friend of mine (given an hour of blind A/B testing) prefered the regular CDP sound with thicker vocals but less realistic cymbals. Of course, he thought the organic thicker sound without the DAC1 was more realistic for vocals.

I was able to accept hearing exaggerated vocal articulation due to the singer using a microphone in the recording process and get past this reality and still enjoy the music whilst my friend found it intrusive (too evident that we were listening to a recording).

Certainly - it is a very subjective subject! And what I describe above was extremely subtle and NOT evident on every recording... on some recordings we were unable to tell which was the source. It suggests that you need to listen to a wide variety of music and recordings in order to make a full comparison and it inevitably requires some compromise. To me the greater the precision the more problems/anomalies you discover in your recording collection.

Al - One review of the Benchamark claims way better performance at 0dB settings for XLR (four jumpers inside) than any other position (-10, -20, -30). I can hear a little livelier sound at 0dB than -20dB but -10dB is much worse and my 0.5m cable has total of only 6pF/ft x 1.5ft=9pF.

Benchmark stated in manual that for XLR:

Setting (dB), Output impedance (ohm)
0 60
10 1600
20 500
30 160

and -10dB is really bad. If you're concern with it - get DAC1 USB. I think that pre has also LM4562 on the output and different divider but verify. I'm not sure how better it is - will check their website for the manual.

Digital newbie here. I have been listening to CD's since they came out.I have found that they are no where near as musical as LPs.Then I got my first DAC. I just got a Audio Alchemy 1.1 DDE and a AA DTL 1.0. This has transported my CD's into another world altogether. Listening is fun again. Now to add to the string: I am using a cheap Sony NS601HP.This has a TOSlink digital out interface to connect to the jitter box/DAC.(It also upgrades std. DVDs to 1080P,which is nice).
It cost about $60.00 at Costco. This setup rocks! My Accoustat 2s now have wide and deep,transparent soundstage with a much sweeter bass and treble than I have ever owned.
Makes me wonder if I really do need that VPI I am bidding on.............

sure I do.

e

Al - are you running XLR or RCA?

RCA at present, because that is what my Rotel cdp puts out, but my Classe CP-60 preamp can accept either.

Regards,
-- Al

The Paradisea tube DAC supposedly reduces jitter as long as the jitter at the source does not exceed a certain tolerance as I understand it.

Not sure exactly how this works. Maybe someone can explain?

It is not the same thing as upsampling and reclocking as like the Benchmark though I am pretty certain.

Still, I have to say though that I cannot hear any clear defects or differences in the sound reproduction using either Roku Soundbridge or the Denon player's transport that I might attribute to jitter.

Mapman - I don't know DAC like that since I wasn't looking, but heard that people had good results with tube preamps. My Benchmark serves as a preamp.

According to Stereophile Bel Canto is a little better (not necessarily warmer) than Benchmark but for 2.5 times more money.

Al - are you running XLR or RCA?

I would characterize the Bel Canto DAC3 as "warm" sounding. No tubes though!

Good info, Kijanki -- Thanks! In my case, I don't want a warm sounding dac. I'm looking for neutrality and detail, because I have a tube power amp, and also a Classe preamp, which while solid state has a bit of a tube-like character as well.

I don't know the answer to Mapman's question. Anyone else?

MacD -- sorry to have diverted the thread a bit, but I trust you've found my previous answer, and the others that have been posted, to be helpful.

Regards,
-- Al

On a different topic, but for those who prefer a "more analog" sounding digital sound, I wonder if there is a tubed DAC out there with jitter control features that are in line with the Benchmark?

Al - Benchmark had all sorts of problems so be careful with used one (and the new one has 5 years warranty for original owner). First problem in very early Benchmarks was thin sounding NE5532 made by Signetics (Philips). Fortunately Philips factory burned down around 2001 and license was bought by TI. Die was redesigned (larger) and the sound got fuller. NE5532 is very fine sounding opamp in spite of the price (but horrible DC spects). Second problem was too high impedance on unbalanced outputs (many people preferred to use headphone output for that) and the final minor problem (that my Benchmark suffers) is a little high balanced output impedance. The worst one is at -10dB settings that is perfect with my amp and speakers. I'm forced to use 0dB position (narrower adjustment range).
USB version has different Opamp (but only for the output stage) - newest and greatest LM4562. National got awards for this amp but mostly for combination of great AC and DC spects in one amp. LM4562 is a stronger amp and output divider was redesigned (reduced impedance). Oh there was also something about limitation to 96kHz at optical. It was changed to 192kHz with rev F. (same rev. F reduced unbalanced impedance to 30 Ohm). Benchmark has 30 day free evaluation program.

Word of a warning - Benchmark is not a warm sounding DAC. According to John Siau it was meant to be neutral because warm sound (exaggerated even harmonics) sounds wonderful with voice or guitar but not with instruments that have more complex harmonic structure than simple overtones (like piano or percussion instruments). He even mentioned that piano might sound like out of tune with some very warm systems. I don't have much of experience in audio and therefore believe in what I read.

There are mods for DAC1. One of them is to change cheap amps to OPA627. Benchmark tried them and they prefer NE5532. They even show which harmonics got worse. Steve from Empirical Audio says that microdynamics (low level performance) is improved with OPA627. Steve also improves power supply - filtering and decoupling. In spite of -140dB measured S/N of the stock units Steve says that dynamic performance is improved (pulse response). One thing not acceptable to me in mods is removal of upsampling scheme. I don't question that it sounds fine but requires high quality transport a not my $60 DVD player.

Kijanki -- Do you happen to know if the dac chip(s) and circuitry are identical between the current versions of the dac1, the dac1-usb, and the dac1-pre? Their site has a comparison chart that deals mainly with functionality differences, but it's not clear to me if there are circuit differences in the dac sections. I'm thinking of getting one in the foreseeable future.

Thanks!
-- Al

Mapman - I think that people who prefer NOS DACs (that definitely require good transport) don't object to upsampling but to digital filtering. I enjoy my Benchmark DAC a lot but recently read review of Meridian 808.2 CD player - upsampling player with different type of digital filter. John Atkinson said "it's the finest-sounding CD player I have yet heard". I hope so, for $17k - My Sony DVD player was $60 ($1060 with the Benchmark DAC1).

keep in mind that the length of the interconnect cable between transport and dac is perhaps just as important as the dac itself.

Correction: At the end of this sentence I meant to say "as the transport itself," not "as the dac itself."

Regards,
-- Al

I'm not familiar with the jitter suppression capabilities, if any, of the Bel Canto DAC3. But assuming they are not comparable to those of the Benchmark DAC1 which Kijanki referred to, keep in mind that the length of the interconnect cable between transport and dac is perhaps just as important as the dac itself.

See the following thread for a complete explanation and supporting references:

http://forum.audiogon.com/cgi-bin/fr.pl?ddgtl&1237611683

It is essential that the interconnect be no less than 1.5 meters long. Longer than 1.5 meters may be ok, but 1.5 meters is generally considered to be the ideal length.

Regards,
-- Al

Agree with Kijanki. Transport can matter but it depends on DAC. A good transport does not necessarily have to be expensive these days also.

I use the transport still in my Denon player with external DAC. The sound is essentially identical compared to same source material ripped to music server and streamed via Roku Soundbridge network player to the Paradisea DAC, which is not upsampling but still has good jitter suppression characteristics supposedly with most decent transports.

Tbadder - That is true. Good transport makes a difference in general but not with asynchronous upsampling jitter rejecting DACs. I'm using one (Benchmark DAC1) that has very strong jitter suppression with very cheap DVD player (DVD players have good tracking). The only thing affected by transport is jitter and once it is eliminated it won't make any difference as long as player/transport is "bit transparent" (doesn't use any DSP processing or digital volume control etc.)

I think I'm definitely in the minority here, but my own experience is that a good transport does make a difference. When I purchased my Lector transport it was the first piece I had ever had that transformed my system, greater coherence and balance. I can't pretend to know why, but I do know that at this point it has stopped me from exploring computer-based systems because I'm too busy listening to music.

I have had a DAC3 for a couple weeks now and have run a 200.00 player and a 1500.00 player as transports. Can't tell any difference. That's why I am selling the expensive player. Cables might make a bit of a difference, but to be truthful I can't tell there either (using the SPDIF inputs--haven't used the toslink or any others on the DAC3 yet).

Hey 4est, I actually have a mac mini hooked up to it right now. I just want a nice transport for when I play CD's. The Mini sounds pretty amazing I do agree.

Before spending the high dollar on a classe or mcintosh, I'd think seriously about a mac mini as a server via usb into your dac3. It is very hard to beat under 5k or so...