The DSA Phono II MM/MC Phono Preamplifier

I reviewed Dynamic Sound Associate's $12,000 solid-state phono preamp in Stereophile's "Analog Corner" October, 2013. It was a "Class A" product all the way other than a few "burps".

One was what I described as "...a midrange-rich whirring that sounded like a distant machine shop—less like pink noise than purple noise." It was far in the background so hardly an issue but when I switched cartridges to the Stein Aventurin, which is based on a Benz-Micro motor the DSA picked up a whirring sound consistent with the Continuum Caliburn's motor located a considerable distance away. For that reason, the DSA Phono II was relegated to "Class B" in Stereophile's "Recommended Components".

The problem solved, DSA claimed (no need to go into exactly what it was), the company sent another sample so I could confirm it, which would gain for the Phono II entrance into "Class A". That's where it will appear in the October, 2014 issue's "Recommended Components" listing.

So while I had it here, I thought I'd give it a short review here, especially in light of the just published Reite Audio review.

One thing's for sure: whether or not you can afford the DSA Phono II, once you'd had a chance to inspect it inside and out, examine its rich feature set and of course listened to it, I think you'd agree it was worth its considerable cost.

DSA, like Reite Audio is a one man operation. Naples, Florida resident Douglas Hurlburt has a masters degree in solid state physics and a PhD in electrical engineering. And he's into vinyl? What is he? A charlatan? I laugh myself silly when reading pompous online posts from techno-geeks asserting their engineering creds to "prove" vinyl's inferiority.

Anyway, Mr. Hurlburt is a long-time a vinyl enthusiast, who has incorporated into the DSA Phono II all of his engineering expertise along with his "wish list" of convenience features. The Phono II includes 3 independently configurable RCA/XLR inputs, each adjustable on the front panel for both resistive and capacitive loading including one input in which you can insert your choice of resistor value and brand on circuit board mounted sockets. Four gain levels—40, 50, 60 and 66dB—can be set from the front panel and there are pushbuttons for mono/stereo, polarity inversion, a high pass filter (rumble) and L-R/R-L—a control intended to approximate azimuth setting, but as the instructions point out, this difference method is not the same as minimizing crosstalk, which is more accurate. Are you liking that so far? In my job I am!

The Circuit

There are four all-FET gain stages, the final three of which operate in differential mode. The input is single-ended only. The dual-mono design uses no global feedback and no transformers though it is capable of up to 66dB gain (not recommended unless absolutely necessary because of added noise—of course operating single-ended you lose 6dB of gain. The output stage employs a separate class-A amplifier for each polarity of the amplified signal, and its fully regulated supply voltages are powered independently of the gain stage voltage rails. DSA claims the unit can output more than 20V peak-peak without clipping.

Because there are no D.C. filtering coupling capacitors in the circuit an occasional "touch-up" of the DC balance and/or offset may be required but it wasn't last time I had the DSA here, nor was it this time.

There's more detail in the Stereophile review, which can be accessed on DSA's website.

In case you are concerned about the convenience features sacrificing signal purity, all of the switching and routing is accomplished via logic-controlled relays. Signal paths are short with boards located next to their functions. the "stuffed" boards are sourced from one company, the chassis from another with final assembly, testing and burn-in accomplished at home. I rightly complained about the overly-bright LEDs and what do you know? The unit I was just sent has a button located under the chassis that regulates the brightness.

Crystalline Sound

If you like warm and soft the DSA II is definitely not for you, but if you like speed and transparency without glare, grain, edge or etch and you value dynamics (of which LPs are definitely capable) the DSA delivers. You must, however, load carefully and associated gear, especially cartridges have to be carefully chosen. It's all about a grand recipe.

I finished with the Reite Audio the other evening and hooked up the DSA Phono II. Forgetting about build quality and features, what do you get sonically for your considerable expenditure? I re-played some of the same records, including Analogue Productions' new mastering of Belafonte at Carnegie Hall (APF-6006) (review forthcoming) and good as the Reite is (and it is very good), the DSA sets a soundstage that has rock solid stability, alarmingly well-defined dimensional boundaries and Saran-Wrap transparency. Clearly there are shades of black as well as gray because the blackness of the backdrop was notably better than the Reite Audio's and the Swan Song's, both of which were quiet (the Reite more so with the .54mV output Etna).

The Lyra Etna, with its rich midrange worked well here but the Miyajima Labs Zero (mono) was ideal, while the Transfiguration Proteus pushed the high frequency extension envelope on some records but on the right ones the combination was "fasten your seat belt" time. The ideal high resolution mate for the DSA II was Ortofon's Anna—at least in my system.

Conclusion

I'll conclude here with what I wrote in Stereophile: "The DSA Phono II was an accomplished performer: tonally neutral, fast, well extended, transparent, superclean, ultradynamic, and superbly detailed. Its top-end performance was addictively open and transparent, with no hint of glare, grain, or glaze. In the attack/sustain/decay department, the Phono II was fast, precise, and clean on the attack, a bit less than fully generous with sustain and decay. Even properly loaded strings may be a bit less lustrous than some might like. But overall, if you don’t like what you’re hearing from the DSA Phono II, lay most of the blame on your cartridge or how it’s been set up.

COMPANY INFO
Dynamic Sound Associates, LLC
1754 Persimmon Court
Naples, Florida 34109

COMMENTS
fy415's picture

What was the cause of the whirring sound from the first sample?

fy415's picture

Since we're "comparing" this unit with Reite Audio's, can you share any interior photos of the DSA's guts? Thanks.

Michael Fremer's picture
I'd been in there when I wrote the original review. I didn't take the time to open it again but it's a different world compared to the Reite. Multiple boards, nicely laid out and isolated P.S. within etc. Sorry I didn't take the time to pop it open again and shoot pictures...
Michael Fremer's picture
Within body of review
Ortofan's picture

...you can have a Nissan Versa – yes, a complete brand-new automobile – or a really outstanding oscilloscope from Tektronix. Compare the relative complexity and it’s difficult to fathom how anyone could rationalize paying so much for this product.

Technically, could the noise issue at the highest gain setting be a result of the choice of FETs for use in an amplifier connected to a low impedance source? Accuphase, for example, uses bipolar transistors in the MC section of the C-27, but FETs in the MM section. Also, why not use a servo to automatically cancel any offset voltage – a method good enough for the Vendetta phono preamp – instead of requiring periodic manual tweaking?

Speaking of which, on another website, John Curl indicated that an updated version of the Vendetta (made with semiconductor devices that are readily available today) would be priced at $8-10K. In that case, if there’s a market for a $12K unit from a relative industry unknown, it would seem that Parasound is missing the boat by not offering an ultra-deluxe version of the JC3+.

ttb's picture

I own the Phono-ONE by DSA. The company says it a dead sonic ringer for the II which adds a whole bunch of features and ease of operation. I bought this because of the stunning sound it has... had to have after I heard in my system- it's that good. So- before you decide on the merits of spending a large chunk of change of a piece of audio equipment - you might should have a listen and find out why audiophiles do drop big bucks on units like the Phono II.

Bill - LKV's picture

Mr. Hurlburt has obviously put great deal of time, skill, effort and himself into this phono amp. I spent an afternoon at a friend's place listening through it. It sure sounded good to me. I was slightly bummed when I read the first review. It seemed a shame that a basically excellent product was tarnished by the glitches MF found. But MF did the right thing in reporting on the glitches in the first place and then giving the design a second look/listen when those problems were solved.

It is entirely possible to get 66dB of very quiet gain from an all jfet design. Before I would critique a design's noise performance, I would want to listen to it in the high gain setting and measure the S/N ratio. I suspect it is excellent and that Mr. Hurlburt's caution against using the 66 dB setting is really just a reminder that one never wants to use more gain than necessary to get the loudness desired. It is a basic principle of audio design that one never wants to amplify the signal, then attenuate it and then re-amplify it. Alost all high end systems with active line preamps defy this principle, but we should keep our defiance to a minimum.

Congratulations Mr. Hurlburt.

Michael Fremer's picture
We at DSA want to thank you for your updated review that gives the DSA Phono II the status that we always believed it deserved a "Class A" rating in Stereophile's "Recommended Components." I also want to address the conclusions that have been drawn by our reference to “excess noise” when using the 66dB gain setting of the Phono II. Due to the use of ultra low noise front end components and a unique design topology, the Phono II has a very low level of output noise power that is obtained without the use of a step-up transformer. This noise level is virtually independent of gain settings 40dB – 60dB. You referred to this in our review when you commented on the “blackness of the backdrop” when using the unit. When a user selects the 66dB gain setting, the noise power in this backdrop will increase by 6dB over that present at the 60dB gain level. However, since the signal is also increased by 6dB, the overall signal to noise ratio is unchanged from that at the 60dB gain setting. There is no impact on the actual quality of sound the listener will experience. Some—who are used to the very “black” background provided by the Phono II—may find the increased noise out of character with unit's overall performance when listening to very quiet passages, or between selections. But they will still be enthralled by the beauty and engagement of the analog experience.
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