[cetoole]

When I missed the 1st round of Alien DAC boards, I decided to do my own board layout to best suit what I wanted. The following is what I came up with. It measures 50x26mm, and for the most part, I just copied the schematic used by the Alien DAC, dropping the BUF634 section, as I only plan to have this bus powered, replaced the regulators with the SOT23-5 versions, which allows the use of TPS79333 and TPS793475 3.3v and 4.75v fixed regulators, which are less expensive than REG101, and pin compatible. I also went to 6.4x13.3 mm film coupling caps for the output, instead of 6.3mm electrolytics. Anyways, I am looking for comments on the DAC and layout, especially ones relating to how to improve it.

 

[t52]

looks pretty good imo.
one question: are the beads for the analog supplies directly under the bypassing caps on top?

 

[cetoole]

Quote:

Originally Posted by t52 looks pretty good imo. one question: are the beads for the analog supplies directly under the bypassing caps on top?

Yes.

 

[MASantos]

Would low value film caps cause a bass roll of? I remember from the Alien dac thread that one should use at least 4.7uf do that you have a low frequency filter.

 

[steinchen]

depends on the input impedance of the following stage. for an amp the value is far from critical, e.g. (@ -3dB)
10k 2uF -> 8Hz
15k 2uF -> 5Hz

 

[cetoole]

I finally got around to having some boards made up by BatchPCB. It will be definitely easier to get the necessary vregs in SOT23-5.

 

[tomb]

These things are very cool! They're only 1" x 2" - about the size of a couple of postage stamps (the little ones)!

 

[rds]

That is very nice. How about squeezing one of those on the miniMax?

 

[tomb]

Quote:

Originally Posted by rds /img/forum/go_quote.gif That is very nice. How about squeezing one of those on the miniMax?

Nope - the fit is too tight. The regular MAX is a different matter, however.

 

[tomb]

The prototype boards shown above are on their way to several people right now. Things have been a madhouse at work this week, but I hope to have a preliminary BOM posted tomorrow evening. Except for the SOT-23 regs, commonality with Alien DAC parts should only be limited by the pad sizes.

 

[error401]

Nice work tomb, maybe a replacement for the AlienDAC project with its pesky, difficult to find SO-8 REG101s. The silk could use a bit of cleanup I guess, but other than that it looks great.

PS. You "stole" my DAC project name! http://www.head-fi.org/forums/f6/min...ve-i-v-292673/

 

[cetoole]

Quote:

Originally Posted by error401 /img/forum/go_quote.gif Nice work tomb, maybe a replacement for the AlienDAC project with its pesky, difficult to find SO-8 REG101s. The silk could use a bit of cleanup I guess, but other than that it looks great. PS. You "stole" my DAC project name! http://www.head-fi.org/forums/f6/min...ve-i-v-292673/

I'm not tomb, but that is basically what this project was intended to be, when I missed the Alien DAC group buy, I redid the layout for my own preferences, and when I saw they were going to make more, I bought some of those, and put this on the back burner until now where the regs are getting extremely difficult to source. There is definitely a few things that need to be cleaned up, and that will happen before any more are made.

Sorry about the name issue, I didnt even think about it. Tom an I have just been calling it the mini DAC in our emails since we started looking at actually getting boards made for it, and just stuck with it as a name. That is the problem with generic names like miniDAC, they have already been used. Guess I could go back to the name of the folder the layout files are kept in on my PC, "PCM2702 DAC".

 

[error401]

Quote:

Originally Posted by cetoole /img/forum/go_quote.gif I'm not tomb, but that is basically what this project was intended to be, when I missed the Alien DAC group buy, I redid the layout for my own preferences, and when I saw they were going to make more, I bought some of those, and put this on the back burner until now where the regs are getting extremely difficult to source. There is definitely a few things that need to be cleaned up, and that will happen before any more are made.

Sorry cetoole, I saw tomb's response and assumed he did it all! Silly me.

Quote:

Sorry about the name issue, I didnt even think about it.

Totally kidding, go ahead and use whatever name you want, I don't plan on my project going anywhere, and even if it did, it's such a generic name...

 

[tomb]

Well, I am tomb

. Colin and I make a great team and I feel privileged to work with him. However, I am not the acomplished board designer. My job is documentation and support.

EDIT: Not a very good documenter at that, I guess this is another instance where I sat on the post too long before submitting it. Sorry for being redundant.

 

[Citizen86]

Would this board be easier to work on than the original Alien DAC? And if so... anyway some more people can get a hold of them?