Greg Smith

Authorized Lexicon Dealer Oklahoma Area

www.themusicshop.com

September 1997

Lexicon DC-1

Quick question: how much time does your audio spend as an analog signal? If you're one of those vinyl-loving audiophile types, it could be the entire length of your signal chain, and you can safely ignore the rest of my ranting here. If you're using a digital source, read on. That digital signal might only stay that way for a brief trip between the digital decoding mechanism and the D/A converter in your player. As for me, I've got the output of my CD player going through some digital cable into an outboard DAC. From there, it heads over some analog cable to a traditional preamp. Right now, the only purpose that serves is to let me adjust the volume. This requires passing through some switching circuitry and a lovely potentiometer, both of which are fiddling with the audio going through them to some extent. This seems kind of silly to me. I've been trying to get rid of my analog preamp for years now, but it's only recently that good digital preamps have dropped in price enough that I could possibly consider using one. Lexicon's DC-1 is the first really affordable unit in this category I've found. The base version retails for $1,995, which might seem on the expensive side at first. But a single DC-1 combines DAC, preamp, surround decoder, and subwoofer crossover all in one remote controlled box. You even get some jitter reduction thrown in. Considering what an equivalent set of individual components could cost you, the price doesn't look so steep. Most of the reviews of this Lexicon unit I've seen have focused on all the surround features available in the top of the line Dolby Digital capable version, priced at $4500. While that's fine, I thought it might be more interesting to look at the far less expensive Basic DC-1 as a budget component for the mostly stereo listener. Doing more in the digital domain has the potential for superior sound quality.

The DC-1 is a lot of things, but one thing it isn't is impressive looking. The black metal chassis is very utilitarian, and the plastic buttons and volume control aren't likely to get you excited. The 20x2 character display let's you know what the unit is up to, with each character rendered in stunning 5x8 pixel glory. As my one visiting friend said, "didn't the low-res character generator look go out with the end of the 70's?" Apparently Lexicon isn't real concerned with how good the front panel looks; after all, many of the customers they are selling these things to are using the on-screen menus you get when the DC-1 is connected to a video display of some sort.

The reason why this display is so important is that there are a ton of things you can configure on this unit. There are eight sources labeled on the front panel and the remote. These do not necessarily correspond with the jacks on the back that bear the same name. There are five video enabled input sources (three with S-video capability) and three audio only ones that you can select between. You can reroute any video input to go along with whatever audio you want to match it with. And, much more importantly for this review, there are two coaxial and two Toslink optical digital audio inputs. You can attach any of these four to whatever source you want to override the analog inputs of. A single digital input could conceivably be assigned for use with all eight inputs selectors if you felt like it. About the only thing you can't do is have an analog input assigned to more than one input choice.

Why, you might ask, would you want to have a digital source that went along with more than one selection? That's easy: also assigned to each of the eight choices are effects. Choices for the effect setting include Two Channel, Panorama, and your usual collection of surround gizmos (Pro-Logic, Nightclub, Concert Hall, Church, Cathedral, Mono Logic, TV Matrix, and the ubiquitous Party). You could take, say, the digital output on your laserdisc player and assign it to the TV and CD buttons, where the TV one gets processed in Pro-Logic and the CD is Two Channel. You want to know how the DC-1 works in surround modes, go read somebody else's review--that's what everybody else talks about. I haven't hooked up more than two speakers to it yet myself. For stereo purposes, you get Two Channel and Panorama as the only useful selections. Each effect has a set of parameters that are associated with it that let you adjust its performance. For the surround modes, this is essential because it lets you muck with all the delays and such that go along with that scene. For Two Channel mode, you get one thing to adjust: sub bass boost. This lets you alter the level of the subwoofer by +/-5dB. If you aren't using the subwoofer output, you don't even get any use out of that.

When you get a new DC-1, the first thing you need to do with it is run through the menus for a bit and configure everything. Initially, I wanted to get my sample so that both my CD players were connected to two different digital inputs with the effects set to Two Channel. Additionally, I wanted the subwoofer and surround speakers turned off. This can be important to check, because if you've got a subwoofer filter going, the bass to your main speakers will be gone. In addition, the Panorama effect works differently if you actually have rear speakers. As I was already familiar with the basic idea of how the DC-1 assigns sources and effects to the input selectors, it took me about five minutes of fiddling to get what I wanted after opening the box and plugging it in. Without reading the manual first, mind you. Then again, I do program computers for a living and have successfully set every VCR clock I've every encountered without any instructions, too. The gyrations required to setup the stereo modes are small enough that I can't imagine it taking too long to configure things even if you're not a button pressing madman, and it's easier to navigate all the menus if you have a video display attached and can see more than one menu item at a time.

My first "you're not so smart after all" moment with the DC-1 came when I was adjusting the front panel display. You can control the contrast to get the best visibility in the amount of light you've got. It's also possible to turn that display off altogether. Thinking that would be neat to try, I did so. Nice black display with only a few lights. The problem showed up a few minutes later: how, exactly, was I to go about turning the display back on now that I couldn't see the menus to navigate to that option? Oops, should have thought that through a bit better. Happily, it's only the backlight that gets turned off--the characters are still there if you get close enough with good light and squint. Lexicon says that even audio-only DC-1 installations might want to get a small TV or monitor to use as a better display when you're doing configuration.

Digital in, Music Out

After verifying that everything was as it should be inside the digital world of the DC-1, I sat back and listened. The gear I was replacing included a CAL Gamma DAC and a Rotel RSP-960AX surround preamp, a combination with the same sort of capabilities as the Lexicon unit but without nearly as much control over what happens. Then again, the total cost of those two and the analog interconnect I also didn't need anymore only came to half what the DC-1 costs. But, boy, did the Lexicon sound better. Mind you, there are many levels of "it sounded better." I write a lot of reviews where I'm swapping around interconnects or other such details, listening very carefully for the subtle changes and reporting on them. This was not one of those occasions. Using the Lexicon as DAC and preamp totally and utterly blew away my older combination, one that I had been pretty satisfied with. It wasn't even close. During complicated pieces of music, it so much easier to pick out the individual instruments that I could hardly believe it. Thinking that perhaps my memory was failing or something, I put the CAL and Rotel combination back. The soundstage collapsed. The bottom end got sloppy. The crisp sound was back to being all mushy again. The biggest difference was in the bass; the bottom end was so much more powerful and well defined with the DC-1 that I could almost swear I was hearing all the way down to DC. By comparison, my older equipment sounded almost tinny in comparison because the lost bass shifted the overall balance toward the treble.

This isn't just one of those moments where things get better just because you got something more expensive. I've heard the improvements you get from better quality DACs and preamps compared with the ones I'd been using. With a digital source, the Lexicon DC-1 could easily hold its own against a more mainstream $1000 DAC/$1000 preamp combination. I've never heard it sound harsh or gritty like many digital products often do, unless I was playing recordings that I know are, in fact, harsh and gritty. Those are reproduced faithfully and painfully, as they should be.

Filter Fun

We haven't even started to look at the other cool features this Lexicon unit offers, features you're not likely to find in any analog product even if you did spend $2000 on it. Since it's targeted for video applications, the DC-1 has a host of bass management features. There is a single subwoofer output that works by summing the bass in the three front channels and rolling off higher frequencies at 24dB/octave. It's adjustable with -3dB points of 80, 100, or 125hz, and should be set to lowest frequency your main speakers can handle. I (along with a number of other DC-1 users) would like at least one more low setting (say, 50Hz). This would make subwoofer integration just a little bit easier with full-range main speakers, as your ear is more forgiving of slight level mismatches as you drop in frequency. As it is, though, I had no problems getting the ACI Titan Subwoofer to match with any of the other speakers I used with the DC-1 crossovers. The very steep digital filters removing higher frequencies were more effective than the ones that come with the Titan, so much so that I found it worked fine even if the subwoofer's internal crossover was set to the highest frequency so that it essentially didn't do anything.

You can argue a lot of things about digital audio, but it's tough to dispute the superiority of steep filters in the digital domain against more traditional analog approaches. Even if you could design a perfect analog filter, parts tolerance and imperfection (i.e. series resistance in the capacitors and inductors) would still leave the implementation inferior to a roll-off done properly in software. For the main speakers, the DC-1 provides a matching set of high-pass filters with a 12dB/octave slope available independently of the subwoofer. You could use them to block low bass even if you weren't utilizing any of the subwoofer features (this is another application I'd like to see lower crossover points for). The combination of high and low pass filters available fit together so well, I don't ever want to go back to integrating a subwoofer without them. The ACI Titan took days of tweaking to get the analog crossover and related parts integrated with my main speakers. It took all of five minutes with the DC-1 doing its crossover magic, and most of that was while sitting on the couch adjusting settings with the remote.

Follow the bouncing bits

Let's look inside the box and see how all this magic is accomplished. The currently selected digital input feeds into the receiver chipset, which in turn heads to Lexicon's proprietary jitter reduction circuitry. Details on what exactly they do aren't released; all they give is the mysterious name, "256FS Jitter Reduction." The reclocked digital audio heads to the DC-1 chipset, consisting of the Lexichip 2 and a host processor which handles all the mundane chores like the display, video switching, remote control, and the like. A 56004 chip handles output to the four stereo DACs. Each DAC is 20 bits wide, matching the internal data path, so if you're using a 16 bit digital source there's some headroom for things like equalization in the digital domain. These eight 20 bit DACs are a good bit of what you're paying for in a base model DC-1. Attached to each of these outputs is a digitally implemented level control. The volume knob on the front of the box serves only to quickly adjust the levels; it doesn't accurately reflect the true volume.

Volume on the DC-1 is set in 1dB units. While initially I thought that 1dB might not be quite a fine enough adjustment, in practice it was sensitive enough for normal listening (if not level matched comparisons with other components). The full range is from -80dB to +12dB relative to the DAC output reference level. That goes from dead quiet to about as loud as a normal preamp (around 6V). I found most of my listening occurring between -30dB and 0dB, with occasional bursts up to +10dB (mostly just to see how far I could push things). Unless you've got some really odd equipment, you're not likely to need more preamplifier output than the DC-1 provides. If you're using the analog inputs, those have a gain control before the 16 bit incoming A/D converter which lets you digitize at full range and keep final output level loud enough. There's an automatic setting which turns itself up and down as needed to prevent clipping while still using all the input range.

There are at least two schemes of volume control that can rightly be called digital. The first processes the digital signal with higher resolution than the source, reducing the volume digitally and having a DAC output that feeds right to the output. Examples of this sort of design include players from Wadia. The problem with that approach is that as you turn the volume down, you start losing bits of resolution. Lexicon didn't feel this was an appropriate approach. They use their digitally controlled gain control to replace the traditional volume control, with no gross volume adjustment in the digital domain. It's still an analog gain adjustment, but there's no potentiometer involved. This approach isn't a new one, with units as inexpensive as Audio Alchemy's DLC preamp implementing it in the past. I suspect you'll be seeing more circuits with volume controls like this as time goes on.

Fine Tuning

After listening to the DC-1 for a while, I spent some time trying to figure out if there were any configuration options that might improve its working in my system. One thing that was nice to find was a digital balance control; I've been buying preamps without one for a while, since I'd prefer to avoid yet another analog pot the signal has to traverse. Since the balance is adjusted in software, there's no fear of degradation with this preamp.

I briefly experimented with the Panorama mode. This works with a stereo configuration, and attempts to improve your listening experience by canceling crosstalk and such. While similar in concept to products like Carver's Sonic Holography circuit, this again has the advantage of not involving a bunch of extra analog processing. While Panorama doesn't have the drop in overall sound quality I'm used to hearing from such processing, I still didn't find it a real improvement in normal stereo playback. By all means, try it yourself; who am I to say it's not a worthy feature? One type of recording I did find it very effective at improving were those made with a binaural recording scheme.

Having settled on Two Channel mode, I also found a Bypass mode which didn't seem a whole lot different. Come to find, the main difference between these two is that Bypass doesn't include the subwoofer bass level adjustment. After listening very carefully, I noticed a very, very slight improvement in the quality of really deep bass with Bypass engaged. Apparently, in addition to disabling all the digital processing, Bypass also mutes outputs other than the left and right. Not having those extra circuits sucking juice out of the power supply leaves more power to run the operative portions, which could explain the minor improvement. Or maybe I imagined the whole thing; I wouldn't bet too much that it's a real difference, but it seemed pretty consistent.

With all the jitter reduction circuitry, I was told the DC-1 was less sensitive to transport differences than many standalone DACs are. I compared my two Rotel players in the same fashion as my CAL Gamma review to see, as the differences with that DAC were subtle but important. With the DC-1, the magnitude of change between the two transports, one a changer with Toslink and the other a single disc with Coax output, was pretty slim. The newer changer had a bit more emphasis on the bass and sounded a bit better overall than the old player, but it was very close. Regardless, my most recent testing verifies that the DC-1 definitely benefits from having a good transport, and I'll be diving into that topic more in the upcoming months.

One oddity I noticed with the Rotel RCD-955AX was that it lost sync with the Lexicon on occasion. When you pause the disc or skip tracks, around one-third of the time the DC-1 panel would inform me that there was a digital media error. This never effected the sound, as it was only a small fraction of a second during a period where there was no output, anyway. But that does go to show just how fragile the digital outputs on some players can be, even a fairly well designed unit like my Rotel. Buzz Goddard at Lexicon informs me this isn't surprising, and is in fact a feature of their product. They intentionally made the DC-1 stringent in what it will accept on its digital inputs. This keeps it from outputting digital garbage. For example, DTS encoded CDs play on regular CD players, and if you actually listen to one without decoding it makes a horrible noise. Most DACs and digital processors, even some very expensive ones, will pass that crap right through. Being very conservative in what it will accept as valid input let's the DC-1 keep the rest of your equipment safe.

The flip side to most digital products is obsolescence. Since new formats spring up all the time, products require at least a software upgrade to keep decoding everything. This has been affecting DC-1 users for a while already. As newer source components that play loose with the digital audio standards are released, Lexicon has been releasing a stream of upgrades that sync up whenever possible with products that have proved to be incompatible. I laugh, because this is a familiar trait if you're into computers. You call tech support; "my new DVD player won't work with my DC-1." The first question: "what version are you using?" If it's not the latest, forget it; that's obviously your problem. For the record, I got V1.01 of the base DC-1 program with my unit.

The Writing on the Wall

Shamlessly using a popular buzzword, audio equipment and traditional computer applications continue to converge. We just recently crossed the line where even inexpensive computer systems are fast enough to keep up with the full audio bandwidth. The strictly digital parts are only going to keep getting cheaper and more powerful, far faster than comparable analog technology will. When looking at computer equipment, I like to look at "the writing on the wall." These are the facts that will drive the market forward regardless of the relative merits of the technology involved. For example, the writing on the wall says that it's no longer possible to introduce a new very successful PC word processor. Even if you were to develop something technologically superior to Word, there's still no way to unseat it. If you don't agree, you need to spend more time looking at the dynamics of software. When looking at the future of consumer audio, I see digital. We've already been living for years in a market where upscale (but not high-end) receivers were converting their inputs to digital so they could do fancy DSP tricks. Now that DVD and discrete surround is here, this trend is just going to accelerate. Who wants to use six RCA jacks if they can avoid it? Not the general public that drives this sort of thing. They want to just run that one digital cable from source to receiver, connect speakers to that, and roll. Why, that's even easier than the stereo jacks you used to need. That's where we're going, and anyone who thinks otherwise probably thinks there's still real life left in vinyl, too.

The funny part is that the audiophiles who started the whole outboard DAC ship moving had the right idea after all. The high-end seems to be leaning toward one-box players as of late, which is way wrong. The clear future of audio says that you'll have a source component used as a transport that outputs digitally. You'll have some number of boxes between that and the speakers, usually either one (a receiver) or two (digital preamp/power amp). I won't shake you up too much by suggesting that one of those boxes will be your home computer, too, but that's moving along as well. Products like the Lexicon DC-1 are the next generation of audio component, using digital technology everywhere it is practical while carefully controlling the inevitable analog portions.

Sure, you can nitpick. I'd like to see a digital output on the back, but I understand that outputting all those different formats is a big pain for a feature few need. I do really want at least one more low crossover point. And while I find the remote exceptionally cheesy for a product in this price range, I can just go buy a hefty Marantz programmable or something if it really bugs me that much. Fact is, in the areas that really count--sound quality and flexibility--the Lexicon DC-1 easily delivers well enough to justify its cost. You can bet you'll be hearing more from me about it, because there's no chance I'll be returning the review sample. It's been making me think all kinds of strange thoughts lately. I've been mulling over that fact that you could drop $2000 for a DC-1, $500 for a decent CD transport, $750 on a power amp, $500 for a pair of speakers, toss in $250 for cables, and put together a killer system for $4000. That's right, I wouldn't consider it out of the question to spend half your audio budget on a preamp, if it's a DC-1 and you get jitter control, D/A conversion, subwoofer controls, and surround out of it, too. Pretty radical thinking, huh?

P.S. to catch further cool chatter about the capabilities of the DC-1, head to the SMR forum, where many owners (aided by frequent visits from Lexicon staff) discuss what they've learned and offer suggestions for fully utilizing the capabilities of its technology.

.....GS (gsmith@westnet.com)

www.avalonav.com
Authorized Lexicon Dealer New Jersey Area