Z-Systems RDP-1 Review
At a glance
- Product: Z-Systems RDP-1
- Description: Digital preamplifier
- Dimensions (W × H × D): 17 × 4.5 × 10 inches
- Weight: 14 pounds
Flexibility and control
When I became formally introduced to the audio societies in New York, paid my member dues (now overdue) and attended meetings, I was quite surprised to see the looks on the elder members’ faces when the word equalizer was slightly mentioned. It seemed as if the word alone causes angina in anyone over forty. As diverse as each member is in their tastes, there seems to be one thing that they all agree upon: EQUALIZERS SUCK! Being one of the newest and youngest members, I guess I agree… sort of. One member from the Westchester society mentioned to me, “Perry… if you can, bag all the grain from your equalizer, and on a cold snowy morning sprinkle it on your driveway, like salt, to melt the snow!” I cannot print what my reply was. Some things never die.
I find it appalling that no matter how well something is made today, you always find those self-proclaimed experts who say it can’t be any good… based on their experience with something they experimented with in 1960! I know that most attempts to build half-decent EQs have been a dismal failure. Until Cello introduced the Palette, despite its cost (fully loaded, about $18,000), it was, and still is, considered the reference standard. My reference standard is my rent! I will never be able to entertain the thought of ever owning a unit priced so out there. Well, hello, wake up, have some coffee and read the latest news. The Z-Systems RDP-1 has, deservedly, received rave reviews in the audio press (Fi, Ultimate Audio, Hi-Fi News & Record Review, Stereo Review, and Audio magazine).
Since seventy-five percent of readers of major audio magazines read the beginning chapter of a particular review, then skim past all the technical data, specs, spectral plots and so on, right to conclusions, I have left the technical aspects out for readers who are forced to ingest Vivarin to stay awake through these types of reviews. There is justification for such technical reviews, and please believe me when I say I know of their importance to some. Except, to me, they have very little importance because it always boils down to how it sounds. Period. I believe most of the readers of PHF will not be bored by technical wizardry, since I possess none. I merely want you guys to know how it sounds. Final. Kapeesh. I am not out to measure its accuracy but its musicality.
I found my heart in San Francisco
Covering the Hi-Fi Specialty Audio and Home Theatre Show 1997 in San Francisco for The Audiophile Voice, and of course to sniff out new products for possible review, my system at that time was composed of all Balanced Audio Technology electronics and Von Schweikert VR4.5 loudspeakers. Notice the B.A.T./Von Schweikert room won second-best sound at the show, yet I was frustrated. Something’s definitely wrong with this picture.
I went from room to room snapping photos for the magazine, saying hello, being cordial, smiling, waving, high-fiving, lying, keeping my mouth shut and being quite dishonest about some very bad-sounding rooms! What are you gonna do, tell a designer “this room sucks!”? The Sound Lab room was the size of my bathroom and they were using the very big A1s!
Visiting the Peter McGrath/EgglestonWorks/VTL/Levinson/Z-Systems/Transparent room was, well, something that has literally changed my life. Glancing over the shoulders of other showgoers who were as interested as I was in this very strange-looking box that appeared to be an equalizer of some sort. But it couldn’t have been; they’re illegal in these parts, or so I thought. The Cello Palette unit exists, but costs as much as a small car. I now strained to get a closer look, flexing my biceps to very casually move anyone in front of me out of the way without even a hint.
It’s an equalizer! A real good-looking one too, with symbols on the front panel I thought I wouldn’t ever see again! There were the all-too-familiar slopes and bell curves that I haven’t touched in years. This to me was unbelievable. Cool, calm and collectedly, I rushed up to the gentleman in the front of the room with a name tag and quietly whispered in his ear (with sphincter in tight mode), “How much is it first, and does it do what I think it does?” His reply was, “Yes, it’s a digital EQ and it retails for 5K!” I sat down (thinking of what I could sell), then listened as Peter McGrath operated this unit, manipulating the sound seemingly with the greatest of ease, yet the sound changed so dramatically! I sat stunned in disbelief, trying to gather my thoughts, which were now racing back to all the equipment I had changed over the years. Countless amounts of money thrown out in trades, deals, and steals. Staring right into my face was the answer to all my frustration, despair and dis-ease.
Boosts and cuts and slopes… oh my!
Designed to sit between a digital transport and a DAC, this six-band graphic equalizer offers four parametric bands and two “Q” or slope shelves. Our Sony DVP-S7000 review covers a period transport, while the dCS Elgar Plus DAC review covers a reference converter from the same era. Like the now-defunct Audio Alchemy boxes and Genesis Digital Lens, the RDP-1 stays entirely in the digital domain, with six digital inputs—two AES/EBU, three coaxial and one optical—and three outputs: AES/EBU, coaxial and optical.
The RDP-1 also incorporates a proprietary feature known as TTC (Transparent Tone Control). This allows total control of all its functions in the digital domain via a digital S/PDIF signal. Most important to me is the ability to handle volume control with no loss of transparency or resolution, as the manufacturer claims. I don’t feel I fully have grasped all the features of this well-thought-out product.
In addition to tone control, you also have two dither selections (16 and 20), with three multi-bit settings as well. Sixteen-, 20- and 24-bit settings are offered to adapt to the wide variety of DACs out there, except the one-bit devices, with which you have to listen closely to choose the best setting. Dither… hmm, I don’t know if I have ever heard it, but I am certain that I haven’t. Systems that employ this nice little trick seem to ensure a very quiet low end.
The “Q” or slope feature allows a user-selectable size in the frequency to be either cut or boosted. An example would be to take 31 Hz and give it a 3 dB boost, and apply a low Q or slope range of 4. Slopes range from 8 being the highest down to 0.4 being the lowest. Note: newer models had their Qs changed to “slope” for a better understanding.
The RDP-1 was used in my reference system, along with Ed Meitner’s BIDAT processor and transport. As a digital cable, I used NBS Reference out of the transport into the RDP-1 and Illuminati D-60 balanced out into the DAC. All amplification was Balanced Audio Technology VK-1000 monoblocks. Speakers were the VR-4.5s by Von Schweikert Research. Tekna Sonic vibration devices (C10s and C12s) were used on the VR-4.5s. Osiris Giza Bases were used under the VR-4.5s and the VK-1000s, and the wonderful Osiris Ariel vibration devices under the transport, DAC and Z-Systems unit. In addition, all components were resting on Black Diamond Racing Cones attached to Those Things (3s and 4s). Cable was Custom House Barracuda. Shakti Stones and On-Lines were used throughout the system along with VPI Bricks, resting atop anything flat—including one reviewer’s head! Another outstanding addition to the system was SCE Audio’s HRS Harmonic Recovery System. No preamp was used for this evaluation since the Meitner DAC has its own built-in volume control—which, by the way, is very different in that it employs neither digital nor analog volume, but somehow manages volume gain and attenuation through the manipulation of voltage. But the B.A.T. VK-3i was around for comparison.
I can “Z” clearly now the grain is gone
I installed the RDP-1 and immediately began to familiarize myself with the unit fairly quickly. I could tell at first glance that it was going to take a very long time to memorize all the uses of this sophisticated device. I began to shape certain CDs to the way I thought they would sound best in my room to me, which, surprisingly, varied greatly from disc to disc. Shaping the room seemed even more enticing. Doing this by ear took a while to get to my liking. Yet when this was done, I was able to achieve results that would be impossible without this unit, regardless of what the ancillary equipment was in the chain.
Much greater bass control became very easily discernible by attenuating the lower frequencies. Clarity of midrange vocals was improved as well, very likely the result of limiting the low energy from the room, thereby freeing up the midrange frequencies. Another major benefit was this increased sense of air, improved perhaps by a neater overall balance. Surgically correcting misaligned frequencies due to the room/speaker placement through the RDP-1 was quite easy once becoming acclimated. Removing clouding and smearing of the upper treble was a pleasant surprise, since I hadn’t yet played with the high frequencies. Transparency in the rear of the stage was also improved; again, this was probably due to the straightening out, so to speak, of the speaker-placement/room anomalies. There is no such thing as the perfectly flat room, but what the RDP-1 showed me is what great sound can be achieved when attempting to address this issue.
Listening to “Mojo” by Big Joe Maher (Wildchild 02352) was an absolute revelation of what the RDP-1 is capable of. The first track, entitled “Got My Mojo Workin’,” is a classic recording. Listening through the RDP-1 made it even more so. Dynamic contrast took new heights; lows were cleaner, with much better pitch definition. Big Joe’s voice seemed better delineated, clearer and more favorably depicted on stage. It’s amazing what can be accomplished by the RDP-1 with what seem like only mere adjustments.
Jeff Sarli, playing the upright bass, with the RDP-1 in bypass mode, was ill-defined; notes hung longer around the woofers and sounded heavier. Big Joe’s voice now sounded a bit too heavy, less transparent and pushed more in your face. Engaged, however, with −10 dB attenuation at around 80 dB, Jeff’s playing now displayed much more speed and finger snapping was more noticeable. There simply was more emotion, more swing, more music and less hi-fi. Instruments were blending into a greater musical picture; the side of the stage seemed to envelop me more. Overall, it came across less routine than I remembered. I sat and listened for hours, smiling to myself.
The next disc I put on was from the very well-recorded ECM label. If any disc needs help, this would be the last; I can put this label at the top of my list for excellence. Dave Holland Quartet, Extensions (ECM 1410 78118). “The Oracle” is aptly named for this song, and man does this baby go. Marvin “Smitty” Smith’s work on percussion is simply something that has to be heard. Remembering how this sounds is easy because I play it quite often, yet somehow the RDP-1 seemed to flesh out more of the CD and less of my room boundaries. For the first time in my listening experience, I got the impression that my room was not adding anything to the recording.
Shaping the lower frequencies down 5 dB at around 63 hertz was a wonderful improvement in articulation and speed. Smitty Smith’s drum thwacks were crisp and clean, with no caffeine or overhang residue. Kevin Eubanks’s guitar came out of the right side of the room filled with mucho ambience. It seemed to come from beyond the wall, making the room seem larger. There was an increased perception of the original recording itself, being projected on the back wall as if by a 3D film projector. Image specificity was never more splendid and rock solid, which I still believe is the only liability of the VR-4.5s. This, my friends, is what it’s all about: getting the room out of the way and making a speaker as large as the VR-4.5 disappear even that much more. Never before has one component made such a difference in my listening room in so many areas.
To pre… or not to pre?
Now came the time to see how much a preamp can affect the system’s overall sound. Putting the B.A.T. VK-3i into the system, and removing the HRS, brought out a few surprises. First was the added soundstage and dimensionality, creating the illusion of being in a larger listening hall. Also, I was very impressed by a very neutral midrange—not too tubey or electronic, just naturally rendered. This is quite an achievement from a tube preamp. The RDP-1 sounded, by comparison, a little dry. Cymbals also benefited from this improvement, sounding more shimmery and shiny. Music sounded more convincing, faster and more dynamic.
Yet I got the impression that the sound also sounded more hi-fi, more like how high-end systems sound when using digital. I lost the sense of ease and tranquility I became enamored by. Transparency took a hit too. Everything sounded a little more etched in the upper mids, sounding a bit harder on the edges. In some systems that may be an attribute, but for me it just seemed to take away something special. I didn’t get the sense that the speakers were no longer in the room; they were more visible due to the enhanced upper midrange, I believe, sounding a hair intrusive. I could see where some could live with this setup due to the added dimensionality and dynamics.
On the other hand, I prefer the more relaxed quality of the overall sound, being more transparent, quieter and with the back of the stage appearing blacker. The midrange was not as rounded or tube-sounding as through the B.A.T. VK-3i, yet, to me, the music was still very convincing and sounded more realistic played through the RDP-1. I cannot offer a higher compliment than that to a digital preamp going up against my reference analog preamp.
Less is more!… More or less
Using the RDP-1 over the last year has been an absolute delight. I now have fun once again. Used as a digital preamp is just one of its many attributes. I am becoming more convinced that digital volume done right will outclass the very best preamps for purity of signal. In my system, it’s a no-brainer. Starting with Ed Meitner’s BIDAT, I was thoroughly convinced that this is the future for systems not using vinyl. There simply isn’t something better than nothing. This is why I find the HRS such a wonderful device. Used in conjunction with the RDP-1, it takes the system to another level, adding all the virtues of a preamp without its liabilities.
I guess you know that I am enthralled by the RDP-1. It is the answer to my problems in this day and age. Using it in a digital-only system only proves what can be done with digital today (look out for the new analog-to-digital unit any day). I cannot recommend the RDP-1 more. Like the HRS, its job is not duplicated by anything else in the chain, and I don’t know of any other product besides the Cello that offers this level of performance—and that unit is designed as an analog preamp. I feel like a recording engineer, finally being able to finely tune my system’s overall sound. Being able to apply the RDP-1’s possibilities in my system has been a real treat. What more fun can be had than to nominate oneself Recording Engineer of the Year! A clear breakthrough product that I cannot recommend any higher.