the bantam dac ROCKS
Oct 25, 2008 at 4:11 PM Thread Starter Post #1 of 36

linuxworks

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just got mine built last nite (actually finished soldering around 3am; maybe the soldering job actually shows that, lol):

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this was not as hard as it looks but its definitely NOT a simple diy unless you have a good/fine soldering tip and have avoided the espresso drinks for the day
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the sound is quite good. I expect to be 'testing' this all day today
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such great fun. good price, too - was under $50 in total parts.

/bryan

update: showing the size of the board

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quite a .... HANDY little dac there. ha!
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Oct 25, 2008 at 4:42 PM Post #3 of 36

krmathis

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Nice work!
smily_headphones1.gif

So tell us a bit more about it. Does it connect through USB?
 
Oct 25, 2008 at 4:52 PM Post #4 of 36

linuxworks

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yes, its simply a 'usb sound card'. usb in and analog out - no spdif at all, anywhere.

even linux can see this card:

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no drivers needed (usb audio is mostly like that).

sounds as good as any of my other dacs. amazing that its just usb bus-powered (not exactly audiophile power supply in a usb bus!) but I guess the filtering and regulation (and the dac) don't mind a noisy computer power supply. I heard no noise or hum from this dac!
 
Oct 26, 2008 at 7:34 PM Post #5 of 36

linuxworks

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Quote:

Originally Posted by myinitialsaredac /img/forum/go_quote.gif
Nice job Bryan,
Let us know your full thoughts. Hope your "testing" goes well. =D



to me, it sounds fine. perhaps even great.

I can't quite trust windows kmixer, though. I want to take that out of the loop but last time I tried, I lost ALL windows sound and it would never come back.

I think linux and mac can do bit perfect (non resampling, non scaling) passthru of audio to usb but windows just insists on 48k resampling if you go thru kmixer. anyone know an easy foolproof way to avoid it? is asio the only way to do that?

other than that, the device itself seems fine. a bit low on its line-out level. maybe half of the 2v standard, so it should really have some kind of buffer or follower stage, I think. when I drive headphones via its own amp, *that* is the buffer so I'm fine, but it still may be a bit on the low level for output, in general.
 
Oct 27, 2008 at 4:01 AM Post #7 of 36

royewest

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I've built two of these now. One with plugs and the other as a "BantamCableDAC." They're still burning in but certainly, for the money, they sound just great -- decent bass, clear separation of instruments, musical, etc.

If I can build one of these, you can.
 
Nov 5, 2008 at 11:40 PM Post #8 of 36

linuxworks

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just got ASIO installed on my windows box. finally broke down and gave in on foobar2000, too
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it seems to work even though my windows main sound system is hosed (wdm is deleted somehow and so kmixer based sound is non functional. maybe that's good)
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the one problem left is: gain. very low output on the dac. it needs a buffer stage with gain, I think. right now I'm running TWO headphone amps in series just to get suitable volume from it. I have my pimeta set to 10x gain and even that wasn't enough on its own (I had to string in some old headroom brand airhead to give enough pre-gain before my pimeta).

so, anyone thinking of building one of these into their phones amp, plan to have a lot more than 10x gain if you have only 1 gain stage after the dac.
 
Nov 6, 2008 at 7:25 AM Post #9 of 36

linuxworks

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its now a cable-dac - just put it in its small box with a bit of plastic cutting and some plastic screws:

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I snipped off the end of some 'throw-away' rca cable and used that for my rca termination. such a short length of cheap cable is surely forgivable..
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and it has those nice pretty labels already on the L/R ends!

tie a knot for a strain relief, feed thru a rubber grommet and its good enough for government work.

plastic box was very soft and easily cut with a dull hobby knife and a hand reamer. the square hole has to be left open at the top or the pc board won't angle into the box.
 
Nov 6, 2008 at 3:34 PM Post #10 of 36

ShinyFalcon

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I have a question... that flat cylindrical thing to the left of the PCM2702, marked Q1 on the schematics, what is that? I noticed something similar on my iRiver H120, and that part gets really hot... and I'm unsure if it's supposed to be hot.

On topic, I would sure like to DIY one of these someday!
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Nov 6, 2008 at 3:49 PM Post #11 of 36

DaMnEd

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It is a Crystal oscillator.
 
Nov 6, 2008 at 4:54 PM Post #14 of 36

linuxworks

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Quote:

Originally Posted by ShinyFalcon /img/forum/go_quote.gif
I have a question... that flat cylindrical thing to the left of the PCM2702, marked Q1 on the schematics, what is that? I noticed something similar on my iRiver H120, and that part gets really hot... and I'm unsure if it's supposed to be hot.


it should not be hot. its not a heat passing or generating element at all (just a crystal).

probably it picks up heat from the board and nearby parts and being metal it holds onto the heat it does find.

is it too hot to keep your finger there? no crystal should be run that hot (unless its an old ham radio set with a crystal 'oven' from the previous century)
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Nov 6, 2008 at 6:47 PM Post #15 of 36

JamesL

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Look what just came out of the oven!



I only made one of them a in-line cable dac since I had already picked up a enclosure for it when it was in proto-phase.
The other two will fit nicely in with a pimeta and ppav2.
I'm waiting on R5/R6 before I solder in the crystal and the electrolytes, but I can't wait to hear them =]
 

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