DAC progress

[Doc B.]

The Hiface is something we're looking into. In the meantime we plan to work with cards that should work very well - EMU 0404USB, EMU 1212m, Juli@, and Lynx II. I use the 0404USB as a USB/TOSLINK interface with my Acer netbook and it sounds quite good. I expect the SPDIF setup will be as good or better.

[2wo]

Bump,

[Doc B.]

John Swenson has been making great headway on the DAC. He is closing in on getting the DAC to automatically recognize the sample rate of a given file - pretty cool. He is waiting for me to send him some funds to purchase a few different sound cards to verify their function with it. And I'm waiting for you guys to buy enough products this week so I can send John the funds...

[Maxwell_E]

Ooh, very exciting. I've been lookin at DAC's for a starving college student budget, and I don't mind skipping a meal or two if it means I can really find out how these AIFF files sound.

[doctorcilantro]

Did you end up deciding on implementing AES? Would be nice to use with Lynx or RME AES cards.

thanks!
DC

[tdogzthmn]

I am curious is the DAC will incorporate a tube and the same overall design theme that the other bottlehead products have.  Also what is the estimated target price for this bad boy?

[John Swenson]

I'm not going to comment on the price, thats not my department! The design uses 1704 DAC chips which have a current output. The DAC chip drives a stepup transformer with an IV resistor after the transformer (PJ is looking into different arrangements, maybe splitting the resistance, some in front of the transformer and some behind, or just all behind, I personally like the all behind). This gives low impedance to the DAC (10 ohms) and still gives some voltage gain before the tube stage.  The tube stage then gives some extra gain and buffering to the output.

This scheme is not very common, many designs put a IV resistor after the DAC chip, but you then have to choose, a high value resistor which gives enough voltage to drive a line output BUT causes distortion because of the high impedance the DAC sees, OR a small value resistor which gives appropriate impedance to the DAC chip, BUT needs a high gain amplification stage (similar to a phono stage). The technique we are using lets the DAC chip see the low impedance, but provides enough voltage gain that the tube stage only has to supply a moderate amount of gain.

The transformer also provides the high frequency filtering after the DAC chip so you don't need to add extra components to implement that function.

Right now I'm working on the digitally controlled super low jitter oscillator that can track any S/PDIF input. The original design philosophy was to send a S/PDIF stream from the DAC back to the soundcard which would sync its output to the DAC, this gives extremely low jitter IF you have a soundcard that supports this function. Unfortunately if you fed it from a source without the sync from the DAC you would occasionally drop bits. This turned out to actually sound pretty good, a lot better than I thought it would.

It turns out the company that makes the oscillators I'm using also makes a digitally controlled version which allows you to change the clock frequency in very tiny steps on the fly. I'm trying out one of these right now and have the frequency changing part working (I got it working about an hour ago!)  With this I should be able to track the frequency of any input. It won't be quite as good as the source synced to the DAC, so that is still the preferred connection, but it should allow you guys to use this DAC with pretty much anything.

On the AES/EBU front, I'm not planning on putting it in the DAC itself, but it does use BNC connectors and you can buy BNC to AES/EBU transformers which should work. My take is that S/PDIF over BNC is technically a better interface than AES/EBU so I'm not going to compromise the DAC by building in what I consider to be an inferior interface. For those that have DACs with JUST AES/EBU you can use the transformers.

John S.

[jrebman]

Things just got a bit more interesting with the announcement of the new M2 Tech Hi-Face EVO, which reportedly will have a clock input as well as some  other goodies, and will sell for under $500.

John, I hope you can get one of these to test with.

-- Jim

[ssssly]

Is there a rough guess as to when this will be available?

I am in the market for a DAC and wondering if I should get something relatively inexpensive while waiting for this or, if this is still a year out, shell out some real cash for something good?

[Doc B.]

It's going to be a least two or three more months before we have it all worked out, and then it will take a little time to work out the final product details. Right now the emphasis is on getting Stereomour shipped, and next week we start our move into our new office. In September things should ease up a bit and we hope to get back on the DAC development.

[ssssly]

Thanks Doc. Guess I'll grab an inexpensive solution while I eagerly await the Bottlehead goodness.

And congrats on the new place. Will it be open for visitors around the Dec timeframe? Should be passing back through the states around then and would love to shake hands with the folks who have fed my addiction for the past 11 years (man it doesn't seem like it has been that long).

Be well

[Doc B.]

Yes, a big part of the move is having a place where folks can stop by and listen to our products, and also learn about various aspects of audio. I plan to start giving classes on amp building, amp design, using tape recorders and quite a few other ideas we have had over the years but only tried a few of. We will also be willing to host audio club meetings, and I'm kicking around the idea of having informal tape, vinyl and high res digital listening sessions after hours.

I just got word last night that the space should be ready for us to start moving in by the end of next week. I have tentatively planned an open house on October 22, but we hope to be ready to entertain visitors well before that date.

[HF9]

Anything new on the Bottlehead DAC forefront? A few minor updates to whet our appetites? :)

[booangler]

bump

[xcortes]

OK guys. So I've been trying to learn a little bit about this stuff in the last days. While I am not at all concerned about the analog part of the DAC I am a little bit underexcited that the DAC won't control the source which really seems to be the ticket. In any case I found that Wavelength makes a USB to SPDIF converter that looks like a good alternative. It is expensive but if I go into digital I want it to be the best possible as is my other BH gear:

http://www.usbdacs.com/Products/Products.html

WaveLink HS 24/192 USB to SPDIF converter:

I know you have been expecting this release for a long time. We were waiting for OSX version 10.6.4 to be released as there were some issues with previous releases. Apple has released 10.6.4 and so we are ready to release the WaveLink product. Since Windows does not support Class 2 USB Audio we had to get a driver capable of working with our product. We therefore have the Thesycon USB Class 2 Audio driver available for our products. All of the new setup is covered in the 24/192 page.

While this will not bring legacy DACS up to the asynchronous capabilities of direct USB connectivity it will do a lot for those people wanting to connect their SPDIF dacs to computers. Since the clock in all transports are changing the SPDIF output also has to change and this is used to control the flow of audio data between a transport and dac. With the WaveLink the clock is fixed and therefore the SPDIF is fixed and this makes the receiver section of any SPDIF connected device to work really well because the internal PLL (Phase Lock Loop) that derives the Audio DATA stream connects at one frequency, locks on and stays there.

This means that the WaveLink has significantly better jitter capabilities than most transports. It also has rates available and shown with LED's for all the popular audio frequencies (44.1, 48, 88.2, 96, 176.4 and 192KHz). The WaveLink is shipped with a BNC connector for the best response and is shipped with a suitable BNC-BNC SPDIF cable and with a mating BNC->RCA adapter if your dac requires this. A high grade USB 2.0 High Speed cable is also included with each WaveLink.

$900 US Retail.