DAC crowdfunding now in progress

I got back from a very busy weekend in San Francisco, where the main thrust was our yearly meeting to discuss Tape Project business. Luckily part of that business was done at Paul Stubblebine's mastering lab, and since he has a couple of Pacific Microsonics Model 2 a/d d/a converters there it seemed like a great opportunity to compare the Bottlehead DAC with that gold standard for DACs.

Model 2s were discontinued when the very rare transistors used in them went out of production. They are highly sought after in the industry for their amazing resolution and tube-like musicality, and these days one typically fetches around $16-$17K. So the BDAC had it's work cut out for it.

The situation was not optimal because the BDAC only got an hour or so to warm up and stabilize before we started the A/B. It seems to open up quite a bit more if left on overnight. Even so it did not embarass itself in the presence of the 10X more expensive Model 2. I gave a nod to the Model 2 for a little higher resolution and a little more relaxed sound. I thought the BDAC did maybe a little better job on the bottom end definition - particularly after we figured out the Bag End subs were not running with the Meyer Sound HD-1 monitors and switched them in. FWIW Paul had to push a lot fewer buttons (none) to set the sample rate on the BDAC.

At some point I realized that I had set the power switch on our protoype battery supply to run both the wall wart and the battery together. When I switched the wall wart off so the BDAC was strictly on battery power the gap closed up quite a bit, with the top end of the BDAC getting smoother and less compressed sounding. That matches my experience in my reference system.

I was also relieved to find that the $1550 BDAC easily outdid an Apogee MiniDAC in Paul's home system. Let's hope so!

Of course you have to take my opinions with a grain of salt since I am so heavily invested in the product. Paul, on the other hand, has at least a couple Model 2s that he uses constantly in his work system. He can and will buy what he feels is the best tool for the job at hand. I was happy to learn that he ordered two BDACs for his home systems.

 
Don't know how this got past me for so long. Probably because I haven't been paying attention to BH for a while. Just found out about the DAC a few days ago and read all the posts. Ordered one last night. Can't wait.
 
I'm sure those involved want us to focus on getting the DAC out first, and that is what we are doing. After we have shipped the first run we will be getting into the battery supply. There are a couple of experiments I need to try before we finalize the design.
 
johnsonad said:
Thanks for the updated PB and Dan.  What's the timeframe looking like for the battery kit?

I can provide a little more detail on the battery kit.  We know the battery supply sounds better, but we will be spending a little bit of time evaluating different battery chemistries before putting out the battery power supply.  I don't plan to spend a whole ton of time on this until the first couple DACs are out the door.

-PB
 
Caucasian Blackplate said:
I can provide a little more detail on the battery kit.  We know the battery supply sounds better, but we will be spending a little bit of time evaluating different battery chemistries before putting out the battery power supply.  I don't plan to spend a whole ton of time on this until the first couple DACs are out the door.

-PB

Will it be an idea to investigate the ultracapasitor technology as Vinnie Rossi is using it in he's upcoming LIO?

This could be a fine kit to offer for the BDAC.
 
kumasan said:
Will it be an idea to investigate the ultracapasitor technology as Vinnie Rossi is using it in he's upcoming LIO?

This could be a fine kit to offer for the BDAC.

Ultracaps are great for quickly absorbing or releasing energy, which is great for a power amplifier (especially a class D amp), and not so great for a piece of equipment that has a constant current draw. 

-PB
 
This is production DAC #1 being assembled at our new DAC assembly station. Next step is to test our new programmers on it. We're getting close...
 

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Today I listened to a while for a nice big line lump that PB found to include with the DAC as a power supply, in place of the more standard wall wart we had planned to use. It makes for a nice step up in sound quality. We will also be listening to different battery chemistries as part of the development of the future battery power supply kit, once all of our evaluation samples arrive.

Front panels have been cut out and are awaiting polishing.
 
We moved a couple more steps forward today. Back panels arrived and are beginning the finishing process. And we got our XMOS license for the Windows USB driver, so you PC guys will be able to use the DAC's USB input too.
 
Just completed hand finishing another stack of back panels. And I came in to find a nice group of DACs in the midst of assembly this morning, after the guys had stayed late last night to push forward on the job.
 
Doc & company, Thank you for keeping us posted on progress.  I would think that to all of us as DIY people, this is just pretty exciting.  I can say for myself that oftentimes the journey is as good as, and sometimes, even better than the arrival.  This chronicling of your best efforts going into the making of the Bottlehead DAC allows us some participation, even if it's "virtual",  in that journey and I'm looking very much forward to the arrival.  Thanks again!
 
Peebs got the main programmer working today and got eight DACs assembled to the point where they can be programmed. We will next test the XMOS USB chip programmer, and then it will be on to final assembly, burn-in and checkout of the first batch. Later this week we will be writing the operation manual, which we will post online.

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The eight DAC's in the photo have their FPGA memory programmed. We ran into a hiccup with the Xmos programming, and John is working on a solution.

We also received all the power supplies today, as well as the back panel graphics.
 
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