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Digital Drive: REVIEW: Curcio Audio Engineering CD12V DAC Processors by C.B.

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REVIEW: Curcio Audio Engineering CD12V DAC Processors

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Model: CD12V
Category: DAC Processors
Suggested Retail Price: $3360 assembled
Description: vacuum tube DAC
Manufacturer URL: Curcio Audio Engineering
Manufacturer URL: Curcio Audio Engineering

Review by C.B. on March 31, 2002 at 09:11:34
IP Address: 68.41.165.80
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for the CD12V


Just finished building the CD12V this week, with about 20 hours listening logged so far. Even though the unit may need some more burn-in time, I feel that the sound is sufficiently "there" to offer a review.

First a bit of background. My reference CD, a Rotel RCD-955AX, has served me well for the past 12 years. It is a modified unit, the biggest change being the premium op-amps in the output stage (I think they're AD825's, but I can't read the writing any more). In my mind, this CD player has always beat out most mega-buck CD players and DACs I've auditioned over the years, especially the ones with the latest single-bit, upsampling technology. The Rotel contains the Philips TDA1541 DAC chip (but with a digital filter and 4x oversampling), and those of you who read Digital Drive will know how coveted it is.

Still, I felt that I should be able to get more out of digital--especially, to remove the inescapable digital "haze" and concomitant listener fatigue of my Rotel. Being a vinyl addict, I was never convinced of the "superiority" of digital. However, the bulk of my music library is now on CD, and I needed to find a way to improve my day-to-day digital listening.

My research led me to the Ah! Njoe Tjoeb 4000, with a tube-based output stage. I bought one sight unseen (unheard?), based on the many glowing reviews here and elsewhere. After three months and much tube- and op-amp-rolling, I decided I didn't like it, and got rid of it. It didn't sound as smooth and "vinyl-like" as my old Rotel!

Now what to do? I considered the DIY route--a TDA1541 or 1545-based DAC, using Thorsten Loesch's "Adagio Lite" design that has been much-discussed here on AA. But being a novice to digital circuitry (most of my DIY projects have been tube-based), and considering that Thorsten has declined to offer any support on his design, I decided this was too risky and abandoned the idea. Other options, such as an AudioNote kit, were less attractive.

I chanced upon Curcio Audio Engineering's webpage. There, I read the description of a tube-based DAC, available in kit form (actually the bare PC boards--the builder supplies the parts), with a TDA1541 at its core. A call to Joe Curcio confirmed that the chip operates in non-oversampling mode (his webpage is inaccurate on this point), with no "brickwall" digital filter, although a digital filter chip is present to furnish "glue logic". I took the plunge and sent Joe a check for $190, for which I got the power supply, digital, and analog boards, drilled and ready to stuff, plus a complete set of docs.

This has been one of the most rewarding DIY audio projects I've ever attempted. With the purchase of the PC boards you get Joe Curcio's complete support--by phone, in the evening and on weekends, if needed. Obviously, Joe doesn't make much money on this kind of sale, but he is totally committed to helping you achieve success--very refreshing. The sourcing of parts is part of the challenge--you can buy some or all your parts from Joe, as you wish, or you can try to save a buck by buying most of the standard components from Mouser and Digi-Key, as I did. Needless to say, unless you have extensive DIY experience and know your way around the ins and outs of parts sourcing, this project is not a wise choice for a beginner.

The basic stuffing of the boards and final assembly is intricate but possible, provided you really pay attention. Double and triple-checking each step is not out of the question. There were some hitches along the way, mostly due to bad components, but Joe helped me find the culprits. The documentation provided with the boards really made me think, more so than in the typical home audio kit, but in the end I walked away knowing a hell of a lot more about digital circuitry and design than I started.

How does it sound? In a word--fantastic. The biggest fear I had was that the CD12V would not offer any improvement over my old Rotel. But not to worry--there is a fullness, a harmonic richness here unlike any I've heard. In addition, strings sound sweeter, not "glaring", which I suppose is another way of saying that the digital grit is greatly reduced. Since I'm using the Rotel as my transport, I was able to confirm the latter by making a direct A-B comparison of the Rotel's analog output with the analog outs from the CD12V. There's no mistaking that any given violin passage sounds sweeter, less gritty through the CD12V.

In addition, the CD12V offers substantially improved dynamics. Due to its huge signal (no trouble driving a passive preamp here!), the whole presentation has width, depth and muscle. Also, because of the increased dynamic range, climaxes are less constrained--in fact, I don't think there is any dynamic constriction to speak of. In general, I'm drawn to listening to CDs much more than previously; I don't find myself getting up and walking out of the room as I did before. CD is now definitely an enjoyable experience. I'm also hearing more details, although this difference is not as dramatic as the others, since my Rotel was already hi-res to begin with.

A few notes on operation. Being tube-based, the CD12V needs a fair amount of time to warm up. It also runs warm, but not unreasonably so. Joe Curcio has built a nice option into the unit--as an alternate tube type, you can run 12AT7s by changing jumpers on the analog board. This is actually Joe's primary tube choice--he claims that the 12AT7 is less "in your face" than the 6DJ8, but the NOS Ediswans I'm using right now have a warm tonal balance and a very smooth upper register, so I may stick with these for a while. The digital interconnect is critical; right now the only one I've found to provide a reliable signal lock is an old molded-head RCA cable I got with a VCR! Perhaps I need to switch to a BNC-type connection with a true 75 ohm coax--certainly do-able with this unit.

Folks, forget all the delta-sigma, upsampling junk out there-this is the one you should check out. If DIY is your bag, then this is your project. Considering that Curcio Audio Engineering is a sponsor of AA, it's a shame that more inmates don't know about his products (I'm apparently the first inmate to have built one, at least the first to write about it). I can confidently state that this piece of gear has affected as big an improvement to my system as any other-speakers and amplifiers included. It's somewhat sobering to think that the Philips multi-bit chip represents a finality of sorts; manufacturers of CD players and stand-alone DACs have almost unanimously adopted the much cheaper single-bit technology, and those multi-bit chips still being manufactured (Burr-Brown, Analog Devices) are likely to be dropped in the future. Which means, of course, that audiophiles should grab up units like the CAE CD12V, because they won't be around forever.


Product Weakness: None so far.
Product Strengths: Harmonic richness, dynamics, warmth, freedom from digital grit, resolution. This unit kicks ass!


Associated Equipment for this Review:
Amplifier: (2) home-brew 200wpc Tripath digital amplifiers
Preamplifier (or None if Integrated): scratch-built Grounded Grid tube-based preamp
Sources (CDP/Turntable): Rotel RCD-955AX (transport); home-brew belt-drive TT based on AR design
Speakers: (2) Newform Research NHB 45 ribbon hybrids
Cables/Interconnects: home-brew
Music Used (Genre/Selections): classical, jazz, folk
Room Size (LxWxH): 30' x 20' x 16'
Room Comments/Treatments: drywall, carpet
Time Period/Length of Audition: 20 hours+
Other (Power Conditioner etc.): speed control/power supply for TT
Type of Audition/Review: Product Owner




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Topic - REVIEW: Curcio Audio Engineering CD12V DAC Processors - C.B. 09:11:34 03/31/02 ( 7)