Q&A With Wavelength Audio's Gordon Rankin Page 3

What are the audible effects of jitter?
As a musician it just makes a total mess of the music. The sounds all closed in and the instruments blur. Most people listen to music and hear the total piece for what it is. I on the other hand like to tear apart music and find instruments and lines for each part and jitter really messes that up for me.

Wavelength Brick USB DAC

You offer a Non-Oversampling (NOS) module for the Crimson and Cosecant DACs as well as a NOS version of the Brick USB DAC. Can you talk about the benefits of the NOS approach?
I used to offer modules for the Cosecant and Crimson for NOS, but really only the Brick v2 is available as NOS unless you want something custom made. The real problem is I don't really like the PCM1704 DAC at all and it is really the only 24 bit-capable DAC chip for NOS. So really the unit would have to be a 16 bit module unless I did something crazy with some really old new old stock parts.

"What NOS does best is remove all that filter computation which makes it all sound so natural."

What NOS does best is remove all that filter computation which makes it all sound so natural. The problem is the top end is pretty messed up so to me cymbals are not that true. Just think of NOS DACS and Quad 57's they both do midrange in spades.

Every so often I put on paper a new NOS design and then just toss it aside thinking of the now 800 or so high res titles I have on my server. Maybe someday...

What are the benefits of over-sampling and digital filters?
I would have loved to be in the Philips, Sony meeting were they came up with the term over-sampling. The engineers were probably ready to kill the marketing people but it does sound better than digital filters. Basically it's simple if you had to make a brick wall filter then the sound would just suck. So you use digital filters to push out the place were the wall hits and if it is high enough then it doesn't sound as bad. I always use slow filters and let the tube output stage kill off all the high stuff in the analog domain and that's what makes a tube DAC special.

"I always use slow filters and let the tube output stage kill off all the high stuff in the analog domain and that's what makes a tube DAC special."

How important is the power supply in a DAC and does USB bus power necessarily mean compromised performance?
Power supplies provide a number of benefits in signal to noise ratio, output capabilities and jitter. For instance just using good oscillators for the Master Clocks are not enough. I designed a really low noise discrete regulator like 5 years ago. We test these with a Standford SR760 FFT analyzer and this design is good to less than 10nVrms below 10Hz. Most of my designs put the power transformer outside the main chassis so that the AC does not effect the analog transformers used inside the units. Good audio transformers have tons of inductance and are like magnets to any kind of AC noise.

"My Office. What you would expect from an engineer filled with test equipment and work area to build most anything."

USB bus power is something that can effect USB cables a ton and therefore anything attached to them. On the Cosecant and Crimson we use the USB VBUS for powering the USB processor and then I optically couple the I2S feed to the DAC section. This makes a lot of sense and works much better than having a common ground with the computer system. But other products like my Proton and the AudioQuest DragonFly which I designed use the VBUS to power the units. When doing that you have to take into account what you are doing and optimize it as best as possible. This is why each of these has a number of high quality regulators and analog pre-filters.

"I can do the same thing with one tube that another company does with 38 discrete transistors or a couple of opamps (which has 100's of transistors)."

What are the advantages of using tubes in a DAC?
Really two reason:

1) I can do the same thing with one tube that another company does with 38 discrete transistors or a couple of opamps (which has 100's of transistors). Each active component to me adds some kind of texture to the sound. If you limit that to one device then you are not changing the sound as much. Tubes are expensive and using all custom transformers adds extensively to the cost but the results are worth it.

Wavelength Cosecant HS USB DAC

2) Tubes + transformers act as a low pass filter to high frequency noise. If you have say a JFET or bipolar transistor after a high speed switching DAC then they will just pass that noise along. But tubes mated with transformers will cut that stuff right off and provide a wonderfully large wide open stage.

Are there any new products in development that you can talk about?
I really can't say that I have been this excited in years about what's going to happen. I am having a hard time sleeping at night because of some of the new stuff we are working on. For the first time in years I can say the band is back together again. I have several people working with me on some new iOS and Android products as well as a totally new direction for DACs and I have my Thunderbolt license, so fasten your seat belts and enjoy the ride.

"I have several people working with me on some new iOS and Android products as well as a totally new direction for DACs and I have my Thunderbolt license, so fasten your seat belts and enjoy the ride."

What do you see as the next big advance in computer-based playback?
We have to really start looking at the future more. Tabs are going to be the new netbooks, desktops are going away, storage is going network and Cloud based.

I remember doing X.25 (precursor to DSL) design in the early 90's and the Bell Company came out and showed us all these connected lines going into a Cloud picture and explained how the network was all one big Cloud where people will be sharing data. Did it really take 20 years for this to become a reality?

I think it's an exciting time for Computer Audio and something that will bring people into the audio fold. But I also have learned that we need to leverage products that make it simple to get there.

ARTICLE CONTENTS

COMMENTS
johnnya's picture

michael, thanks for a fantastic q/a with gordon rankin; it cuts through the iusual written under brush, with concise, comprehensible information. now, if i could only afford one of his signature products :)

johnnya

Michael Lavorgna's picture

And thanks for the kind words johnnya.

Steven Plaskin's picture

These were my first impressions of Gordon's asynchronous USB interface for the Crimson I posted at the Audio Asylum on 11/28/2007:

Wavelength Audio has just released Asynchronous USB function for the Crimson USB DAC. The Crimson can be easily updated as the code is on a removal EPROM. Jitter is reduced in this mode. I think that Gordon is the first to have successfully executed this USB function. I will leave it to him to explain the technical aspects of Async Iso USB mode.

The improvement in sound is quite noticeable. Detail, focus, and control are the most obvious changes. For example; listening to James Taylor's new album, One Man Band, JT is now in better focus. Previously, his image was more diffuse and less defined in space. The guitar strings have greater detail. Again, with the previous code, everything was softer sounding-less focused. This is not to say that the former sound was anything less than excellent, but the improvements I am hearing now are quite striking. I also noticed an improvement in the bass; better defined and tighter.

I'll be doing some more listening this weekend and report any other improvements I hear. For now, the Async code is really something else!
 

earwaxxer's picture

A very exciting time for DACs!

Charles Hansen's picture

Several years ago at Ayre we were interested in doing something with computer audio. There were a number of different approaches to take -- servers (with everything built into one box, including a simplified computer dedicated to audio playback), Ethernet (which the UK companies have focused on but require complex dedicated software, and a strong understanding of computer networking), and USB (which can use any music player software you prefer, and is trivial to hook up and use).

A mutual friend introduced me to Gordon when he was first starting work on the asynchronous USB code. Ayre had never built a separate DAC, because the only way to do it before (and maintain compatibility with other brands) was using S/PDIF, which inevitably adds a significant amount of jitter. When he told me what he was working on, the first words out of my mouth were, "What do we have to do to license your code?"

We hit it off very well, as we really have the same interests and goals -- it's just that he does it with tubes and we do it with solid-state. It took him over a year to work out all the wrinkles, but there was absolutely nobody else in the business who could have done it. Gordon has a super-strong background with the deep-down internals of computers, and he has a real high-end sensibility. Basically my role was to keep egging him on -- when he would get stuck, I would just tell him, "Gordon, you are the smartest guy I know. If you keep working on this, I know that you will figure it out."

And his asynchronous code changed the entire high-end audio industry. For the first time, a computer-based system could sound better than any other digital source. It meant the end of the format wars between DVD-Audio and SACD. Any computer built in the last five or ten years can do 192/24, and now with DoP (DSD over PCM), playback of DSD files are possible with a compatible software player and USB DAC. And as Gordon has since proven with the DragonFly he designed for AudioQuest, great sound doesn't have to cost a boat-load of money.

I've got a few inklings of what Gordon is working on now, and I think it has the potential to be even bigger than asynchronous USB. No wonder he has trouble sleeping at night! Hats off to Gordon for moving the entire industry forward, and thanks to Michael Lavorgna for a great interview. Exciting times, indeed...

Charles Hansen, Ayre Acoustics, Inc.

labjr's picture

I've had Wavelength gear for 20 years. People are still wowed when they hear it. Looks cool too! What impresses me about Gordon is that he goes all out to try new technologies and ideas to make products. Doesn't seem to be like a typical company with budget restraints etc.& trendy ideas.

Should be interesting to see (hear) what Gordon does with the Thunderbolt license. The optical cables would seem to be preferable for their obvious advantages like long length and galvanic isolation.

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