RMAF12: Channel D and their silky sonata in the key of Seta

I’ve been using Dr. Rob Robinson’s “Pure Music” software program for a couple of years now. I prefer it, one, because it works as advertised, and two, because it was vastly less expensive than its chief competitor at that time. It supports my audio server platform of choice (a Mac), and it supports what was at that point very cutting edge, the so-called “integer-mode” operation, said to make the very best DACs out there sound even more transparent and natural. I’ve stuck with it since because it is still good — it’s easy to use, it does what it’s supposed to, and provides function without me having to learn a whole new way to organize my music (it uses iTunes for organization). On my machines at home, I’ve been able to audibly lift the performance of my server using his software — a claim I can’t make categorically about other “must have” computer audio solutions.

Which brings me to Rob’s latest toys — hardware.

Seta, which Rob tells me is Italian for “silk”, marks his line of audio tools for those of us coming into computer audio. In this lineup, Channel D offers four options:

  • Model L: support for low-output cartridges, $3,799
  • Model H: support for high-output cartridges, $3,799
  • RCM: an optional RIAA correction module for $999 (internal) or $1,299 (external)
  • Nano: an itty-bitty version of the Model L, $1,599

Now, the Model L and the Model H do not, by default, ship with an RIAA curve. You can buy a model to implement one, of course — that’s the RCM. But most customers would probably opt for Pure Vinyl, a Channel D software solution that does a ton of stuff more than just apply curves — you can archive your LPs as 24bit/192kHz computer files! And that’s not all … hell, there’s almost too much to talk about — go here for the scoop on what PV can do for you.

Back to the Seta — an upgraded “Plus” model can now be had, for $5,399. The new model …

… represents the continued evolution of Channel D’s ground-breaking ultra wide bandwidth Seta “flat” phono preamplifier. The Seta Plus includes an updated, ultra low impedance, low noise rechargeable internal AGM battery power supply based on the original Seta phono preamplifier design, delivering superb transparency, detail and three-dimensionality for vinyl playback, a key benefit of the Seta’s ultra wide bandwidth battery-powered design. An optional, high quality headphone output is available.

Okay, now — for those of us not archiving vinyl or looking for vinyl playback assistance, Rob has another tool for those of us working with the DAC-direct playback approach, that is, using a DAC and its digital volume control to facilitate a simpler, more direct, signal path.

The problem with the approach is attenuation. Most digital attenuation has a sweet-spot for its application — which is about -10dB. More than that and you risk “throwing away bits” and possibly start losing resolution. Now, no, not every DAC does this — just most. If you have a DAC, and you’re >10dB off of “unity gain” (ie, deafening if you’re using most solid-state amps), you might want to check out the Channel D Seta DAC buffer ($2,799). This is another in-line analog unit that sits post-DAC, and works to provide a set level of volume attenuation which your DAC’s high-quality digital volume control can then be used to make the finer adjustments. The box is fairly plain, but houses a high impedance (2MOhm!) FET input buffer that feeds into a fully-passive attenuator network with .1% precision so as to not foil any common-mode noise rejection, which then feeds into RF-bandwidth (aka, very wide) buffer with output of 20hms. In case you were wondering, 20ohms is really low — my DAC, a Berkeley Alpha, has an output impedance of close to 1kohm. While it can and does drive amps directly, and with authority, a 20 ohm output makes mismatches impossible. The attenuation is available in fixed 6dB steps from 0dB to -30dB. The unit is, at present, 100% balanced — and only available that way as a single-ended version is still in the works. Given the ultra-low output impedance, the Seta Buffer might also be a superb headphone amp — though, you’re going to need some custom headphone wiring to pull this off. I’ve asked Rob for a unit to play with, so I’ll have more to say about the Seta Buffer shortly, I hope.

Also in this room, which featured the always remarkable and utterly beguiling Joseph Audio Pulsars, here paired with some choice amplification from Hegel Audio, were a pair of Bag End subwoofers. Not something I usually see paired with Joseph speakers, which are known for their alarmingly deep bass. But, for the sake of argument, it was really interesting to see what you could do with crossovers run directly from Pure Music and/or Pure Vinyl. It’s actually pretty slick, and only possible with a DAC that has more than 2 channels of output — which suits the Lynx Studios Hilo DAC remarkably well. Sub integration, even in an oddball room like what you’d find in a hotel, can be a snap — and here, it was pretty much invisible. As it should be.

  • Lynx Hilo 192kHz ADC/DAC ($2,495)
  • Joseph Audio Pulsar loudspeakers ($7,000/pair)
  • Artemis Labs SA-1 turntable ($8,000)
  • Kuzma 4Point tonearm ($6,000)
  • Ortofon Credenza Bronze cartridge ($2,200)
  • Hegel H20 power amplifier ($6,000)
  • Parasound Halo amp for subs
  • Bag End SE12 subwoofers

Hurricane Sandy hit New Jersey pretty hard, so Rob held up the release of both Pure Music 1.9 and Pure Vinyl 3.1 on the off-chance of something untoward — so that there would actually be someone there to answer the inevitable email and phone questions. Lucky he did — he was offline and with no power for two weeks! However, I talked with him today, and everything on his end seems to have come through okay. And yes, both software packages are back on schedule for release — Pure Vinyl will release this coming Friday (11/16) and Pure Music will follow a week later (Black Friday). What’s new? Well, with Pure Vinyl, you’re going to get an improved editor and some tremendous usability improvements. Rob tells me that a well-known vinylophile, who shall remain nameless but who hates computers, has said “ooh, that’s much better.” Pure Music will get nearly two dozen new features and improvements — an interim release about a month from now will include even more goodies and bug-fixes.

While I had Rob on the phone, I asked him about Pure Music 2.0. He loves it when I do that. “Oh, it’s definitely coming”, says he. Any details, asked I? “Nope — but it’s going to be really really really really awesome”. When? “No comment!”

Stay tuned.

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  1. In my experience digital volume controls promise a lot more than they actually deliver. Auralic is promising “loss free” digital volume control on their new VEGA DAC, I’m not sure how they achieve that, perhaps the mega upsampling provides enough headroom to make it possible. All of the traditional digital volume controls though I’ve found to be far inferior to a first class active linestage, and even a well matched passive pre with a top quality stepper can usually humiliate a “perfect” digital volume control.

    Steve is very adamant that the Overdrive’s volume doesn’t act like a digital control, and for good reason.

  2. I’m not sure I understand the usefulness of the DAC buffer when a preamp such as the W4S STP-SE does the same (and more) for a lower cost…

    The STP-SE provides a unity gain impedance buffer, has a well designed resistor ladder volume control, is balanced end-to-end (and also accepts unbalanced inputs and outputs) and it has way more steps for the volume control. Throw in a remote and I find it hard to justify buying the Seta DAC buffer.

    Am I missing the point?

    PS: I did purchase Pure Music too so I definitely appreciate their software products 🙂

    • I think some folks in the DAC-direct camp would shudder at the thought of using any volume control other than a digital one. The problem (and one they might not even be aware of), of course, is bit loss and the drop in resolution to take the volume from unity to “normal listening levels”. Digital volume can be awesome — and completely transparent. But not with 20-30dB of attenuation. So … you’ll either need a preamp (like the STP-SE) or “something else”. The “something else” category might well be something like a Seta Buffer — with a 2MOhm input (vs the STP-SE @ 60KOhms) and a 20Ohm output (vs the STP-SE @ 113Ohms), that this should be able to make any DAC drive any amp across any length of cable. That’s pretty cool.

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