Workin' Man Audio
Dave Duvall


May 1996

31133 Via Los Colinas Suite 111
Westlake Village, CA. 91362
(818)707-2610 fax

So here's my dilema. I have an opportunity to listen to a couple of products, that while they aren't cheap, have a potential to break the vinyl vs. digital barriers. Do I not write about them because maybe the price doesn't fit the "Workin' Man" format, or do I share my experience? The answer: RATIONALIZE! TALK MYSELF INTO JUSTIFYING EVERYTHING! I'm not gonna short change you, oh mighty reader types-I'm gonna tell you what's going on!

So here's the deal. Open up Stereophile's latest list of Recommended Components. Check out the price on transports and D/A converters. You've got a few things around a grand, but the bulk of them are in the "don't let your significant other know how much it really cost you" range. Now, things start to come into perspective here. While these black boxes aren't cheap; compared to a lot on this list, we aren't doing so bad. The key would be - are we getting value for our bucks? See, I told you I could make this fit the format (sorta).

Audio Alchemy DTI.PRO 32

The original DTI (Digital Transmission Interface) started the search for "fixing what's wrong with digital". I still have one in my system, and it was a milestone product for the betterment of digital sound. Jitter reduction, as best stated by Robert Harley, meant getting "the right amplitude at the right time"; and the DTI took steps to do just that. So the father (DTI) begat a son (DTI PRO); a second cousin joined the family reunion (DTI V2.0); and the son begat a grandson (DTI.PRO 32). I've always wanted to use that "begat" thing; sounds so worldly! Apologies to the ladies for using the male references there.

The DTI.PRO 32 combines an ultra-low jitter clock recovery system, along with a Texas Instruments 32 bit floating-point Digital Signal Processor (DSP). AA claims this processor is 50% more powerful than the DTI PRO's processor. Input is fed to a Crystal Semiconductor CS8412 input receiver, which sets the "primary lock" on the buried clock signal. After this "primary lock", the signal is sent to either a 44.1 khz or 48.0 khz voltage controlled oscillator (VCXO) to, in most cases, achieve an ultra-low "secondary lock" with a bandwidth of 5hz. This "secondary lock" insures that any remaining jitter components are not correlated with the music. In some rare cases, "secondary lock" may not occur. This would be due to an imprecision in the transport's internal clock; and though you'd still be able to use the PRO 32, you would not be getting it's best performance. In this instance your transport would need to be adjusted or replaced.

Next, the virtually jitter free signal is fed to the Texas Instruments 32 bit floating point DSP chip. Here it undergoes interpolation, which increases the data up to 24 bits. Output of this "enhanced" signal is routed to either the I2S bus (refer to my earlier V3.0 review), as well as to a Crystal Semiconductor CS8402A data transmitter, whose output formats are BNC coax (BNC adapter supplied), ST glass or AES/EBU.

Next step in the process, is to create the best interface possible with your D/A converter. This is accomplished via user selectable dither. (7) settings are possible: HDCD (turning off resolution enhancement, so as to not corrupt the HDCD encoded signal), 16, 18, 20, 22, 24 bit, and none. To get the best sound you can, you need to know or experiment with, the number of data bits your DAC can handle. The key here is that the input receiver, digital filter, and DAC chips must all be able to pass the amount of bits you select. Fortunately, the V3.0 I use can pass 20 bits from start to finish. The 22 and 24 bit settings are currently for professional use, but don't be surprised when these higher word lengths are available for home use. The V3.0 can pass 24 bits up till it hits the DAC. Hopefully, this will be another part of the upgrade path, that AA is always designing for. While DVD may one day obsolete all of our current gear, and is probably 2-4 years from full implementation, people like AA are taking further steps to improve digital playback, as we know it. AA appears to always be user friendly, in that regard, with it's upgrade paths.

One further word on the dither selection: Don't lose your owners manual! To set the dither, you need to use the phase and input buttons together; to cycle through a series of LED settings that tell you which mode you're in. This is done by reading the number of power LED's that are lit, and referring to the manual to break the code. You'll probably memorize the settings you need soon enough; with me its either 20 bit or HDCD. With the V3.0, if you were to chose 16 or 18 bit, you'd merely be truncating part of the signal, and reducing linearity. BAD THING! Spelled D-I-S-T-O-R-T-I-O-N.

You can change the phase of the signal by 180 degrees, by using the phase button on the front panel. The PS4 power supply is standard, and you can upgrade to the PS3 or PS2. I know one individual, who has said that unless you're using the PS2, you'll not reap the full benefits of the PRO 32. For my use, I have a PS3 on the V3.0 and the standard PS4 on the PRO 32. I tried switching the two power supplies, but achieved better sound with the mentioned arrangement.

This will be my only warning to you. If you don't want to hear digital take a closer step to the vinyl sound, or if you're faint of investing more money into your system; DO NOT LISTEN TO THE DTI.PRO 32! This standard size AA box will majorally improve the performance of your transport, make you find a shelf to store your original DTI on, or possibly have you selling your DTI PRO. Advances are rapid in digital playback (and recording); and this is one hell of an improvement, in particular, over the original DTI. I insist (pushy little bugger, ain't I) that you ween yourself off all coax connections, and ride the I2S bus! Focus and clarity are sharpened, bass is tighter and fuller, and the presentation becomes deeper via I2S. I've done coax between the DTI.PRO 32 and the V3.0, but can hardly sit through one selection before wanting to switch back. LONG LIVE I2S (or better)! Sorry S/PDIF; you're inferior and outdated. Another word of advice; once you've converted the chain from coax to I2S, do not use any further downstream S/PDIF connections. We'll talk about a full I2S chain, when we get to the DDS PRO.

When turning off the Resolution Enhancement, I noticed the change in clarity; particularly in the low level information. Picking up on the little nuances that the Resolution Enhancement offered, is what adds to the life of the music. It increased fullness and palpability to what I was listening to. The entire frequency range appears to have a greater sense of ease, without the bass getting fat and lazy. This translates into a less aggressive, less in your face, less harsh texture, that has been so often attributed to the "digital sound". I was also now able to hear deeper into the mix, with less smearing and more individuality to events. The improved jitter reduction that the PRO 32 offers over the original DTI, is also easily spotted. By putting the sample amplitudes where they belong, referenced to time, I hear more of the spatial cues and focus that must have been originally recorded.

I took this opportunity to do a comparison between HDCD and 20 bit playback. The new Doug McCleod disc, "You Can't Take My Blues" (AudioQuest AQ-CD1041), comes with two discs of the same material. Disc one is recorded using the Apogee AD-1000-20 Super Encoding system with a DTI.PRO 32, and disc two is HDCD encoded. Both were listened to via the I2S connection. First off let me say hands down, the HDCD sounded better than the Apogee, when listened to via the original DTI and the V3.0. Certainly the Apogee recording was superior to a lot of the mass produced discs on the market; but HDCD has a way of layering the soundstage better, providing more details, and to my ears, giving more truth of timbre. This race became a little closer when playing both back with the PRO 32. While I still preferred the HDCD recording, I knew that listening to the Apogee recording would now be a pleasure and more involving than with the original DTI.

Two things became evident in my listening to the DTI.PRO 32. One, digital doesn't have to be a chore to experience; and two, there's not a prayer that I'll be without a DTI. PRO 32 in my system for long, once I return these review samples. My belief that the I2S format is considerably better than S/PDIF, is now that much stronger than first experienced with the original DTI/V3.0 combination. The DTI.PRO 32 is a little black box with lights, that will help you get away from listening to hardware, and back to listening to music. And that, my friends, is why we're all into this hobby.


Audio Alchemy DDS Pro Transport

May 1996

The DDS PRO is a two box transport with the power supply being separate of the transport mechanism, controller, and display. The DDS PRO utilizes the Pioneer Stable Platter system, which requires the disc to be placed label side down, and fully supports the disc over it's surface while spinning. Separate shielding is done within the transport case to isolate the different stages from one another. The outboard power supply has 12 separately regulated, low impedance regulator/buffers; in an effort to provided filtered, low noise DC.

Output is via the I2S bus, or S/PDIF data is clocked to an ultra-low jitter master reference oscillator; for output with BNC Coaxial (BNC adapter supplied), AES/EBU or ST glass (optional). A remote control is provided, but you'll have to turn on the lights, for other than a few basic operations.

Transports are pretty easy to evaluate. In my system, they sit top shelf, and are easily moved in and out of the system with only a couple of connections. I've got no excuses not to switch the two transports a couple of thousand times, and give this a thorough listening to. Unfortunately, these two are miles apart in retail price, but what's a rookie reviewer to do? Consider this though, I believe that when many audiophiles make the initial switch to a high-grade transport, such as the DDS-Pro, they are usually moving from using their old CD player with a digital output, just like myself. Besides, there was a time, not-so long ago, when your CD-Player WAS the only transport you could use.

So, I popped my Rotel RCD-955ACX player into the system (which now included the DTI.PRO 32),hooked up my Cardas High Speed Digital/Video cable (previously reviewed in Soundstage! please check the Archives), and spun "Pictures at an Exhibition" by Mussorgsky as performed by the Philharmonia Orchestra, and conducted by Louis Maazel (EMI CDE7 67781 2). The Rotel/Cardas combo creates a warm, sound with a full, rounded bass.

Inserting the DDS PRO, and using the Cardas cable on the coax output; the warmness of the Cardas cable still comes through, but several things are different now. The focus has been dialed in a bit, and the bass is not as bloated as with the Rotel. Vocals have taken on a different appeal; sounding more realistic, and less mechanical. With all the improvements in quality my system gained with the Cardas cabling; I'm now hearing further steps toward curing "Digititis".

I then tried the DDS PRO connected via the I2S link, directly to the V3.0 DAC. The overall presentation was not as warm, owing in part to the Cardas cable being out of the chain. Bass is better, tightening up a bit. Still, I can certainly tell that the DTI.PRO 32 is absent, as I'm missing the full picture that the music encompasses.

Putting the original DTI in the system via coax from the DDS PRO, with output handled via I2S to the V3.0, yielded no improvement over I2S direct from DDS PRO to the V3.0. While the sound of "Wicked Game" on Chris Isaak's "Heart Shaped World" (Reprise 9 25837-2), is plenty listenable and somewhat pleasing; neither of these last two combos had me reaching for my wallet. The DDS PRO via I2S to the V3.0 is definitely an improved sound over the Rotel/original DTI; but a little voice was telling me this ain't audio heaven, yet.

So, it was time to quit the foreplay and head for the big bang. Hooking the DDS PRO transport to the DTI.PRO 32 and the V3.0, via the I2S format throughout was astonishing! I haven't listened to vinyl in this system; but I am now reminded of all the good things I've heard in other all analog systems. The space and air is there. The low level detail is there. The truth of timbre and realization of instruments and vocals hanging in space is there. To top it all off; the focus is incredible. It's as if another veil has been lifted, and you can peer directly at the performance. As I said in my review of the V3.0, I contribute the increase in focus largely due to the I2S bus format. Put coax back in, and prepare to hear the bass get a little too ripe, and images to lose a bit of their sharp outlines.

Many CD's from my collection, to this point, were pleasing musically, but not sonically. The Rolling Stones "Get Yer Ya-Ya's Out" (Abko 80052), now reminded me of the 4 vinyl copies I went through during the seventies and eighties. Even last year's "Pulse" by Pink Floyd (Live C2K 67065), which always seemed too thick to really enjoy; now opens up and lets me feel the music. The Q-Sound effect on this disc, now creates an enormous soundstage, that must have been intended, and I had not been fully able to exploit. On Emmy Lou Harris' "Wrecking Ball" (Asylum 61854-2), another thick mix, it all now sorts out to something more than a soup of combined background sounds. Dynamic passages such as those found on Chris Isaak's "Going Nowhere" and "Things Go Wrong", from "Forever Blue" (Reprise 9 45845-2), now sound like a combination of voice and multiple instruments; not voice and some one thing making noise.

Another area, in which the DDS PRO and the I2S link excelled was pace. When I'd (try to) go back to the Rotel/coax setup, the music would lose some of it's rhythm and pace, seeming to drag a bit. As far as a disc that's a little too bright is concerned; the DDS PRO/I2S isn't going to cure or sugarcoat that over. Putting the Cardas digital coax cable in will, though I doubt I'd bother. Even my brightest discs never became overally strident, beyond listenability, with the DDS PRO/I2S rig.

Further listening to the soundtrack of the "Patriot Games" (RCA 66051-2) and Holst's "The Planets (Deutsch Gramaphone 439011-2), clearly demonstrated how the areas of space and air would no longer be ruled by vinyl. Layers of depth were well defined as decreases in amplitude; imparting a feel that events truly are physically shifted back in the soundstage, as they are positioned further back from the microphones, or placed there electronically in the mix.

I know I've been drooling a bit, here. I can't help it. After a couple of weeks of listening to almost 1/3rd of my collection, I'm absolutely loving the synergy the full blown I2S system has with my other components. If I had to sum up the DDS PRO, DTI.PRO 32, V3.0, I2S setup in one word; I'd have say everything sounds so "right".

But if it helps my credibility (the devils advocate in me speaking), I'll nit-pick on a couple of things. The display intensity and the size of the readout characters on the DDS PRO, are a little hard to read from the listening position. The locking plastic coupler on the umbilical cord from the power supply to the transport, seems a little cheesy. The silver function pad on the front, I feel, would look better in a one row, horizontal layout; as opposed to the two row vertical arrangement. Bet you noticed none of that had anything to do with the sound. Sorry, nothing but praise in that department.

Now, there's a few things I still want to know. One, what do the open-minded vinyl aficionados of the world think about this setup? Two, will you readers insist I lose the "Workin' Man" title if I lay down the green for the DDS PRO and DTI PRO.32? If you do, I will respect your wishes; but I will also refer you back to my statement in the DTI.PRO 32 review about the Recommended List of Components, as well as my original introduction to this column. There I mentioned "it still takes some bucks to get it right", keeping in mind that right is a relative term. You can certainly enjoy musicality at a price level lower than the $9,500.00 retail value of my system, after I go shopping for these two new components. The good news is, it'll perform like a million bucks!

Till next time...

See Ya....Dave Duvall