Bob Ludwig On Digital Audio
[Mr. Ludwig is the Chief Engineer at Masterdisk, one of the most respected and well-known CD and LP mastering facilities in the country. While researching a recent article on Ludwig, db Magazine found that 48 out of the country's top 200 records were mastered at his facility. Ludwig recently sent a short article on digital and analog recording to BAS member and Stereo Review editor at large Michael Riggs. Michael passed it on to us, and we are printing a slightly modified version here with permission from both parties. — Ed]
It seems that my opinions about recording systems are being misquoted in certain quarters, so I'd like to set the record straight. First, I want you to know that I am a musician. I played first trumpet in a symphony orchestra before I was employed professionally as an engineer. Maybe I speak with forked tongue?!
When the CD was invented (and I mastered the first CD ever mass-produced in America, Born in the USA) I stopped buying vinyl records.
I listen to alot of music. On wide-range acoustical music, where hall ambience and background silence are important to the experience, I always prefer a digital medium — CD or DAT. Having cut records my whole professional life, I never once thought of pops, ticks and stamper rumble on a disc as anything but totally unmusical. Obviously a lot of vinyl mavens have different criteria for distinguishing music from noise. Rock, as with any music of restricted dynamic range in which pops and ticks on a pressing are not such a nuisance, sounds fine on vinyl. In fact, I think the LP gives the most hi-fi per dollar for this kind of music.
Regarding the resolution of the CD and the LP: I can make a digital recording of an LP that would sound identical to the original to almost everyone in a controlled A /B/X test, but I don't think even the high-end writers would suggest that one could make an LP of a CD that would be indistinguishable from the CD! This comparison reveals what I would call resolution, and to me the CD far surpasses the LP in this regard.
The question of musicality, however, is a more complicated one. I believe the LP to be the more musical of the two formats. Now, what does this mean? And is the vinyl disc inherently a musical medium, or do we think it so because our ears have grown accustomed to it, so that anything different is de facto less musical?
I engineer many CD reissues of old recordings, and often the CD sounds to me far superior to the original LP. There are times, however, that the LP sounds not only better than the CD but also better than the original master tape! Sometimes the echo seems to last longer on the disc than the master; sometimes there is more spaciousness on the LP; sometimes the record sounds brighter or more "open" in the top end. Since I cut a lot of these LPs in the first place, I know there was nothing "artificial" done to them.
What is going on here? My CD master tape sounds identical to the original output of the analog recorder, but the LP sounds better than either of them!
To help answer that question for myself, I have done the following trick: I make a DAT recording of the surface noise of the particular pressing I'm comparing, perhaps from the 3 to 10 seconds of silence between movements. With a digital editor I make a long loop of that noise. Then I play back the loop of the surface noise and mix it through my console with the sound from the original tape. Presto! The CD master sounds nearly identical to the pressing. It is brighter and more spacious, and the echo seems longer! Take away the record noise from the CD and it again seems drier and more closed-in than the pressing. There are certainly some interesting psychoacoustic phenomena here! So potentially, in some areas, the LP can offer greater musicality than the CD. It is not more accurate, but in my opinion it is sometimes more musical.
Also, in many cases a good original pressing will simply be more enjoyable to listen to on a good system than a CD. This is because all too often the CD is poorly made — done by inferior engineers on inferior equipment, without the artist or original producer having a single thing to do with the process. The artist and producer probably baby-sat the original recording through many hours of careful mastering and care in manufacture, but it is now seemingly no longer cost-effective for the record company to hire them to do it again. I have mastered the LPs on hundreds of gold and platinum recordings, but have been hired to do only a small fraction of their CD reissues because of the cost. Frankly, I can't listen to the new, butchered versions of some originally very fine records.
One final point: It is hard to make an unmusical sounding LP (ticks and pops aside), but it is easy to make a rotten-sounding digital recording. We spent a lot of money on Pygmy Computer Systems (64-times oversampled, 1 bit Delta-Sigma) analog-to-digital converters and we have a $9000 Wadia professional (meaning, among other things, that it has a +4dBm output) D/A converter to make the digital data sound good. A special converter like the PCS eliminates the degradation that can sometimes occur with normal professional equipment.
I think the introduction of Bob Adams' dbx converter chips and the Pygmy Systems converter have upgraded the sound of digital audio a lot; note, however, that these have become available only very recently. In the current CD catalog there are precious few recordings made with these good converters. I think that when they hear the new CDs on good-sounding equipment like the Wadia or the Sony 77ES CD player, a lot of critics will shut up!
— Bob Ludwig (New York)
[The critics will eventually hear the new CDs with the Wadia or Sony converters, but it is not in their nature to shut up, any more than it is in ours. — EBM]
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