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Anyone heard this dac before? http://www.passlabs.com/pdf/old%20product%20manuals/d1_om.pdf


I have the opportunity to buy one, but I can’t find much on it.


It came out in 1997 but the features look impressive. The specs remind me of the Bryston BDA-1, but what it lacks in the latest digital technology it seems to gain in superior analogue implementation.


-24bit 96khz dac (the dac has the upgrade).


-volume control: The output level is adjustable using a 24-position switch that operates as a differential shunt between the two polarities of the I/V D/A converter


- Output stage: The I/V conversion in the D1 is accomplished with single Mosfet device operated in common-gate single-ended Class A mode: 25 watts. " In a typical D/A system, the I/V D/A converter consists of either an operational amplifier operated as a phase inverting summing junction or a variation of the same circuit using discrete transistors. In either case, negative feedback is used to achieve low distortion.When negative feedback is used in a high gain circuit, stability problems occur when the feedback is exposed to the high frequency transients that are generated by the digital circuits. The transient noise created is not directly audible but since the feedback loop must process both it and the musical signal, reflections into the audible band do occur."


- Jitter: In the D1, the digital input is switched through low capacitance relays through a digital transformer to a Crystal digital receiver. The Crystal receiver is used to feed a phase lock loop system that clocks the digital filter and D/A Converter circuits. In addition, the Crystal receiver reduces jitter to as low as 20 picoseconds at digital zero. The circuit also uses a Fujitsu PLL with Lithium Tantalate crystal that are optimized for DVD and 96 kHz data rates.


-Power Supply: The power supply of the D1 uses two shielded oversized toroidial transformers. One powers the digital circuitry and the other powers the analog section. Both power supplies have individual regulators for each circuit section and are at least triply regulated.


-Inputs: The input system offers AT&T, AES/EBU, SPDIF, and Toslink inputs.



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  • 5 weeks later...

My Minerva demo was quite ear-opening. And I've heard several, including the Berkeley, and LOVE the Minerva (and it's DAC2 twin). I'm surprised you thought the Weiss is rolled off at the extremes, and sounds harsh. What input were you using? Did you try AES/EBU or try it's intended one..the firewire input?


What about the older Pass D1 impresses you the most? Least? How is soundstage depth? Imaging? Detail? Tonal accuracy?





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For those of you out of the loop, Ted is referring to my post here http://www.audioasylum.com/cgi/vt.mpl?f=digital&m=145592 where I do various comparisons of the Pass Labs D1 vs the Weiss, the Emm Labs DCC2, the PS Audio Digital Link III and the Meridian 568.


Excerpt: “went to a local dealer to listen to the Weiss; I brought my Pass. The test system consisted of Magico V3 speakers and Reference Ayre Amps and Preamps, CD players.

We compared the Weiss vs the Pass as DACs, using the Ayre preamp (since the wWeiss was already connected to the preamp). The Weiss struck my as having a similar lush/filled out tone and forward sound of the EMM, my friends concurred. However, while my Pass sounded analogue, smooth, organic, and musical, to my ears the Weiss sounded harsh, and sterile. It was not musically engaging at all. I could not imagine the musicians were in front of me: it sounded like the sound was coming from a stereo, digitally processed. We later heard the Weiss bypassing the preamp. While the music sounded more direct, I had the same reaction as when listening to my Meridian’s digital volume: that I needed to turn up the volume to hear any detail.”


The transport was the Ayre CD player using the dealer’s AES cable. Sure you can claim it’ll sound better with firewire, but from my on experience, while reducing jitter can do a lot, it doesn’t change the fundamental characteristic of the dac. Besides, my Pass Labs was using the same transport. So unless you want to argue a 12 year old dac has better jitter reduction than a supposed state of the art dac, let’s call it a wash.


I disliked it for subjective and objective reasons. Subjectively, I believe the type of sound it creates is wrong. It’s a digital sound with an over-emphasized midrange (just like the Emm labs has). It’s very impressive sounding at first, but over an extended period of listening with these types of dacs, when I compare it to something like the Pass Labs, I realize it’s not very natural at all. It’s kind of like when photographers over saturate photos or use HDR effect ( ). It’s too sweet. You lose all the delicate tones, details, and dynamics.


Objectively it’s not a smooth dac. If you compare it to something like the PS Audio Digital Link III or the Benchmark Dac1 I’m sure it sounds smooth… but compared to my Pass Labs D1 it was very harsh. To be fair I don’t think my Pass Labs is the smoothest as I know the Emm Labs to be smoother. So is smoothness all relative? Am I being nit picky? No…. real life is the benchmark for smoothness. And that’s the point of HIFI, is it not?


My friend who owns the Emm Labs was also not impressed with the Weiss.


The things that impresses me about the Pass Labs the most (besides the fact it’s 12 years old) are its naturalness and analogue sound nature. It has the same level of detail as the emm and weiss, and imho has better dynamics and tone. My friend has related to me it has no sins of co-omission.. it doesn’t do anything wrong.


The one thing I wish it did do better was present harmonic richness truer… but I think maybe that’s what the EMM labs and Weiss try to do with their over-emphasized mid range, but fail at.



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sixty9, my experiences could no tbe more opposite from your. I have heard a lot of high-end DACs and CD Players. To my ears, the Weiss is an exceptional unit. The last word I would ever use about it is harsh. I find it to be smooth and liquid and to be more laid back than harsh. Perhaps there was something else going on in the system? I find the Weiss to have a very analog like sound with an extremely natural sound.

I am also a fiend for detail. I can tell you beyond a shadow of a doubt that the Weiss does not smeer any details or subtleties. That is just plain not true. My system is extremely resolving and I can audibly tell the most minor of changes. To say the Wiess over emphasises the midrange at the cost of other things is just not the case. My recommendation would be to spend more time with a piece, and preferably in your own home, before making blanket statements that come across as facts rather than simply your experience.


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I respect that audio is never black and white, and system configurations can affect the performance of a component.


Everything is relative. I'd like to point out that before i got my Pass Labs i thought the EMM Labs was the epitome of digital reproduction and did no wrong. It was only after a comparison against the Pass labs have i been able to view it from another point of view.


I do not feel i have made any blanket statements. I've only made relative statements (DAC A is smoother than DAC B, or if you prefer, DAC B is harsh compared to DAC A), and have justified any personal opinions by pointing out it's my own subjective opinion.


My opinion on the nature of the sound of the EMM labs did come from listening to it in my own system for a week. I do feel the Weiss has a similar sound signature (midrange bloat), and thus I’m confident enough to post this subjective opinion. BTW, my friend who owns the EMM Labs agreed with me about the bloat after he was able to borrow my DAC for the same week.


Finally, IMHO, if you experience one component is smoother than another in the same system (a system probably more geared towards the Weiss than the Pass Labs since it was the dealer's), you don't need to spend another week with it to confirm that it is indeed smoother. The other 2 people in the room also agreed with me about the smoothness.



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