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Comments for my PCM2702 DAC layout? - Page 3

post #31 of 613
I'll have a fire lit under my tail with this project on Friday/Saturday because I want to integrate it into the same case as a Starving Student

I'll do my best to update how it goes before then.
post #32 of 613
I gotta say that this looks pretty cool. You've got me interested so I will be looking back at this thread often and so I am self-signing me up to see when the first batch is out.
post #33 of 613
Looks nice, one could cut a hammond1455 120mm case in order to make it just the right lenght to fit the mini3 and this new bantamdac! Shouldn't be too hard.
post #34 of 613
Quote:
Originally Posted by FallenAngel View Post
I'll have a fire lit under my tail with this project on Friday/Saturday because I want to integrate it into the same case as a Starving Student
That's what I was thinking as well! And with the ptp layout shouldn't be too hard to reconfigure I believe to add in the DAC later if I built the amp first (which in my case is most likely how it will happen).
post #35 of 613
I'm wondering much clearance there is above the tallest part. Rather, can the DAC be slipped into the higher slots of the 1455C801/2 such that a different board can be placed in a slot underneath it?
post #36 of 613
Quote:
Originally Posted by joneeboi View Post
I'm wondering much clearance there is above the tallest part. Rather, can the DAC be slipped into the higher slots of the 1455C801/2 such that a different board can be placed in a slot underneath it?
It'll be as tall as the tallest electrolyte you put in, which will likely be 10-20mm. Even if the 'other' board is perfectly flat, with no components, it will likely not fit with the bantam in the 1455C801 - notice that there is only 14mm between the highest and lowest slots.
post #37 of 613
Quote:
Originally Posted by JamesL View Post
It'll be as tall as the tallest electrolyte you put in, which will likely be 10-20mm. Even if the 'other' board is perfectly flat, with no components, it will likely not fit with the bantam in the 1455C801 - notice that there is only 14mm between the highest and lowest slots.
Yes, but FYI - I have built an Alien DAC with one 1000uf and three 330uf capacitors laid horizontal with extended leads and it tested equal or slightly better than an Alien with standard components. So, there are possibilities if you want to build one really flat.
post #38 of 613
Quote:
Originally Posted by tomb View Post
Yes, but FYI - I have built an Alien DAC with one 1000uf and three 330uf capacitors laid horizontal with extended leads and it tested equal or slightly better than an Alien with standard components. So, there are possibilities if you want to build one really flat.
Very true
In fact, I already bought a case for it.. the usb connector fits flush inside if I trim a half mil off the support-pins and has about a mil on each side of a TREAD board, so heres hoping I find someway to make this work. =]
Can't wait for the board release.
post #39 of 613
I know this has been answered a dozen times, but how low can we go on the output capacitors? With such a small board, it might be possible to fit a couple of PIO caps inside the hammond 1445C801.
post #40 of 613
Quote:
Originally Posted by MASantos View Post
I know this has been answered a dozen times, but how low can we go on the output capacitors? With such a small board, it might be possible to fit a couple of PIO caps inside the hammond 1445C801.
Depends on the impedance of what you plug it into. The corner frequency of the filter will be , where R is the input impedance of the amp and C is the output capacitor value. You probably want to keep this corner below 10Hz.

I wouldn't go below 2.2uF unless you know you'll be using it with a high input impedance amp only.
post #41 of 613
Colin, Tom, KUDOS! Another BantamDAC lives! With Pavels C16 note, it all works first shot. A little shaving was needed, as he mentioned too, on the USB jack, but that's not much of a problem. I was worried for a bit since I broke a pin on IC1. It happened to be the NR pin, so I've still got a seemingly perfectly functional DAC. I haven't got much test equipment here, other than an old dodgy multimeter, so I'll have to take proper measurements some other time and see if I need to replace that chip.. though so far, so good.
post #42 of 613
Quote:
Originally Posted by ruZZ.il View Post
Colin, Tom, KUDOS! Another BantamDAC lives! With Pavels C16 note, it all works first shot. A little shaving was needed, as he mentioned too, on the USB jack, but that's not much of a problem. I was worried for a bit since I broke a pin on IC1. It happened to be the NR pin, so I've still got a seemingly perfectly functional DAC. I haven't got much test equipment here, other than an old dodgy multimeter, so I'll have to take proper measurements some other time and see if I need to replace that chip.. though so far, so good.
Yay! Way to go!

Questions, of course -
What'd you use for CL/CR and how does it sound?
post #43 of 613
I'm using BGs, 47uf. It sounds pretty much like the alien does and considering the size and cost of it, thats dang good! No noise when paused and max volume (mini^3, ultrasone PL750s) These BGs are new though, and just started getting muddy (just 2 hours in). I'd like to compare it with a BG alien sometime since mine's been dissected already :P. Offset is pretty low, <2ma, but I don't trust this multimeter much v=4.73, 3.27. I'm not sure what implications the lack of NR on IC1 has yet though.. I'll try get a replacement soon anyway.

Edit: just to clarify, I'm pretty certain the muddyness I mention is from the blackgates. I'm pretty familiar with it by now. From memory alone, this is pretty much how I remember an alien sounding when firing up with them, I probably wouldn't be able to tell the difference.. I'm happy with this tiny thing I'm bobbing along to some electronic tunes right now. It has not let me down! thanks!
post #44 of 613
Cool! If it sounds pretty much like the Alien at this reduced size, then cetoole has another winner!
post #45 of 613
The BantamDAC prototype has been declared a success! Boards have been ordered and should be available in early October.

Pics below are of one I put together on Sunday. It took me about 4-1/2 hours, not counting scrounging around for parts. Sound is very similar to the Alien, but with the recommended 3.3uf Wima MKS's, the BantamDAC is a bass puncher with great detail. IMHO, it sounds better than the Black Gate Aliens I have built.





(click for bigger pics)

Cetoole has altered the productions boards slightly. I'll post pics of the new layout tonight, unless Colin beats me to it today. Here are the important changes from the prototype in the photos:
  • Layout was altered to allow clearance from the USB connector (note the surgery around the USB socket in the pics)
  • A power LED was added.

Further details will be updated in the coming weeks at the BantamDAC website: http://www.diyforums.org/BantamDAC. Our intent is to have the board and build cost, without case, limited to $25. In addition, we have a couple of unique applications planned for the BantamDAC, so stay tuned!
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