TNT-Audio >
How did you start designing audio systems?

DW >
After studying electrical engineering I was employed at Studer Revox in the PCM Lab as it was called back then. That was in 1979 when Studer started doing Digital Audio. There were no sampling frequency or interfacing standards for digital audio at that time, so it was a logical step to do a sampling rate converter and interfacing box for interfacing the various digital audio recorders already on the market. Other projects pursued in the PCM Lab at that time were A/D and D/A converters, preview delay for disc cutting, multichannel digital audio recorders (DASH), denoising etc. In 1984 I started Weiss Engineering to develop a modular digital audio processing system for Mastering Studios. I worked in cooperation with the Harmonia Mundi Acustica company in Germany. They had a Studio for CD Mastering and therefore knew what was required in that market. In addition they organized worldwide sales for our products. It was the time when the CD gained its popularity and thus digital audio equipment for Mastering Studios was required. Mastering Engineers are the most discerning listeners, because their ability to shape the music determines how the CD will sound in the end.
Today we still make equipment mainly for Mastering Studios - and for audiophiles of course..

TNT-Audio >
You work in both pro and consumer market. Which are the differences between a professional and consumer product?

DW >
As for the sonic quality of the products we at Weiss do not make a difference between professional and consumer products. For both types of products we strive for the best quality we possibly can achieve. The same is valid for the quality of craftmanship.
For professionals the products sometimes have more features, while for consumers the ease of operation is important. For example we have a digital equalizer in our professional product line, which has seven bands of parametric equalization, each band having three parameters (boost/cut, center frequency and Q-factor). This gives 21 parameters to begin with and then there are many more for other purposes. We plan to do a digital equalizer for consumer purposes, but it would not be a good idea to give the consumer that many parameters to play with, I guess he would soon feel lost. And then there is the cosmetic issue, consumer products have to have a better look, because they should look nice in the living room, while the professional products have more of a "form follows function" approach of design.

TNT-Audio >
Which are the most important elements / caveats in a digital system?

DW >
Digital systems operate on an electrical representation of numbers, i.e. they are systems of applied mathematics. Unlike as with analog systems, environmental parameters like temperature, mains voltage, vibration etc. do not have any influence on the quality of a digital system (provided the system continues to operate correctly). This is the main advantage of digital systems. (Of course analog to digital and digital to analog converters are analog systems and thus subsceptible to those influences.) There are some basic parameters in a digital systems, like sampling rate and wordlength. Both have to be of proper (minimum) size. Besides a minimum requirement for these two parameters for audio applications, their optimum size is often dictated by the algorithm at hand. E.g. for certain algorithms a larger wordlength is required than for others, or a higher sampling rate is required than for others.
In analog circuits the sonic quality is determined by the quality of the parts used and by the topology of the circuit. With digital there is not only the algorithm itself, but also how that algorithm is implemented on the processor at hand which determines the quality. So there still are a lot of degrees of freedom in digital which can be used to make a good (or bad) sounding device. And of course there are several issues in sampled and quantized (i.e. digital) systems which are fundamentally different to analog systems, or which simply do not exist in analog systems.
As an example for such an issue: The sampling rate dictates the maximum representable frequency in a digital system. For the CD sampling rate of 44.1kHz the maximum frequency allowed is 22.05kHz (half of 44.1). Now if anywhere in the processing chain there is a nonlinearity, then frequencies above 22.05kHz could be generated, but in a digital system with a sampling rate of 44.1 this is not possible and thus such a frequency would not lie above 22.05 but somewhere below it (so called aliasing effect). And of course that can be very disturbing. In an analog system this would not be a problem.

TNT-Audio >
How much important is the cabinet/chassis in a digital system? Do you think that its material (copper, steel, aluminium, wood...) can have a significant influence on sound?

DW >
As mentioned above, a digital system per definition is a computer which operates on digital numbers represented by "current / no current" signals. As long as the current / no current states (bits) are clearly distinguishable by the computer, then there is no influence by any external parameter. If there is an influence then the computer is not working properly anymore, but it would have to be a severe disturbance that something like that happens. E.g. your PC does not show false characters most of the time, right? Only analog systems are subsceptible to "low level" influences like the material of the chassis or the cabling etc. Again, one has to bear in mind that analog to digital (A/D) and digital to analog (D/A) converters are analog systems.
You may say a CD transport is a digital system, so why is there such a lot of fuss about the sound quality of CD transports? A CD transport has its D/A converter in an external box. If we talk about the sound quality of a CD transport then we actually talk about the ability of that D/A converter to convert the bits coming from the CD transport to analog signals - provided that the CD transport reads off the bits from the CD properly. This leads us to another parameter of sampled systems which is the timing accuaracy of the sampling process. An analog to digital converter samples (measures) the analog signal at some fixed timing interval. For the CD this interval is 1/44100 th of a second. Ideally the timing interval is absolutely the same every time, but in nature that interval changes slightly at every sample taken. This changing is called jitter. Now, in a D/A converter there is also a timing uncertainty (jitter) in the sampling frequency. The designer of the D/A converter tries to make that jitter as small as possible, because it compromises the quality of the D/A conversion. In the case of a CD transport feeding a D/A converter, the D/A converter has to lock to the sampling frequency of the CD transport and also has to make sure that the jitter coming from the CD transport does not have a (substantial) influence on the quality of the conversion. So in essence one can say that with a properly designed D/A converter, the influence of the jitter at its input is minor and thus the influence of the quality of the CD transport is minor. That means that if you want to judge the sound of a CD transport (or of a digital system in general) you have to make sure that you have a properly designed D/A converter for that judgement.

TNT-Audio >
What is your opinion on multichannel audio? And about SACD and DVD?

DW >
If you like the multichannel recordings then go for them. It is as simple as that. We have to keep in mind that every recording, mono, stereo or multichannel, is not something which brings the concert hall to our homes. It simply does not work that way. It is a "snapshot" of an event, processed via microphones, recorders, various signal processing equipment and last but not least judged by a sound engineer who shapes the recording according to his/her taste. So any recording is something artificial with its own esthetics. If you would like to have the concert hall then you have to go to the concert.
This has implications for the reproduction at home. It means that you are "allowed" to shape the sound according to your taste, you may set up your speakers the way you like etc. etc. Of course you can argue that you would like to reproduce the event as closely as the sound engineer has captured and processed it. But one has to be aware that even that is difficult to achieve. Your Hi-Fi system at home is different from the one the sound engineer was using, your living room acoustics are different etc. etc. So it is a perfectly valid statement that you should not hesitate to shape the sound according to your own taste. Even such potentially severe sound shapers like equalizers are fine. Just learn to operate it in a tasteful way.
As for SACD and DVD: I would prefer to have only one format - the DVD and its variants, DVD-A namely. On the other hand, the SACD is fine from a sonic viewpoint, it only is the pletora of formats which is disturbing - and the fact that more and more productions are recorded in DSD (the underlying format of the SACD). DSD can not be processed directly, it has to be converted to PCM for processing. And after that back to DSD again. (PCM means Pulse Code Modulation and is the format used for e.g. the CD, where a 16 Bit wordlength / 44.1kHz sampling rate PCM format is used. Other PCM formats can have arbitrary wordlengths and sampling rates.) That does not help with the sound quality of course, so in my opinion we should work in the PCM domain right up to the final conversion to DSD for the SACD. Of course this is of minor concern for the consumer, and if he is happy with the SACD or the DVD-V or the DVD-A, then he should go for the format. All formats are fine if you like what you hear. Even the data reduced DVD-V....

TNT-Audio >
Do you think that there will be a market for tube and analog products at a professional level? And at a consumer level?

DW >
For both professional and consumer applications tube and analog products in general have their applications. I have to make some distinctions though: Professional applications: The sound engineer uses whatever equipment he/she needs to achieve the particular sound he is looking for. For this every tool is ok as long as it does not compromise the sound (too much) in other respects.
Consumer applications: In my view most consumer equipment should be made as transparently as possible, i.e. without any coloration as far as possible. At Weiss we try to make all equipment as transparent as possible, except for those units which are meant to shape the sound, like e.g. an equalizer. CD transports, D/A converters, A/D converters, amplifiers, pre-amplifiers, speakers on the other hand should be as transparent as possible, because their job is to convey the musical information without any alteration. Of course one can have a different opinion, because one likes the way that particular tube amplifier sounds. This is a valid opinion as well, but one has to be aware that there is some coloration going on all the time. The coloration may work for a certain kind of music and may work less well for other types of music. This is the drawback with systems which have a inherent coloration. With an equalizer on the other hand, I can shape the music according to my preferences.

TNT-Audio >
How important is music for you? For example, do you play any instrument, or are an Opera fan? Which kind of music do you prefer?

DW >
Of course I like music, all kinds of music actually. From classical music via minimal music and rock to something like acid jazz - everything which sounds interesting and moves something. I don't like the charts though... I took violin lessons for years and also play the bass guitar and some keyboard in a band.

Daniel Weiss - www.weiss-highend.com

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