My latest project - DAC + headphone amp

[gmarsh]

Originally posted by Robzy

I was actually refering to the SRC4192, and i cant seem to find the AD1986 on your board anyway... :S.

Still, im flabbergasted at the design.

Rob.

I started out with the SRC4192, but it turns out the SRC4192's DLL loop has a corner frequency in the KHz range - the AD1986 in "lock" mode has a corner of a few Hz.

They're pin compatible, so I just soldered in the AD1986 instead and didn't bother recreating the part in Eagle.

[Robzy]

Originally posted by gmarsh


I started out with the SRC4192, but it turns out the SRC4192's DLL loop has a corner frequency in the KHz range - the AD1986 in "lock" mode has a corner of a few Hz.

They're pin compatible, so I just soldered in the AD1986 instead and didn't bother recreating the part in Eagle.

Gotcha

Rob.

[ashok]

Hi Gmarsh,
I couldn't open the link you gave
http://rapidshare.de/files/2470563/HD1.zip.html or
http://rapidshare.de/files/2470563/HD1.zip

How do I download that file ?
Can you email it to me directly ? I would really like to see your design.
ashokm (at) sify.com

Thanks.
Ashok.

[tobias_svensk]

gmarsh, sure i want to buy it. How could i talk to you by email? yours is disabled. it would be nice if you could mail me
tobias_svensk (at) passagen.se

Thanks

[skyskraper]

same, id love to see the files. sean@oep.com.au

[kimschips]

Hello qmarsh.

Completely and very very nice work you done there!

I am also interested in your construction files with schematic.

My email adress is kimschips81@yahoo.dk

Have you thought about a group buy for the pcb or how can I order one from you if so?

Just one questen: I have an cdplayer with digital output with ligthwire and a RCA plug output.
How can I connect one off the digital output to your DAC input?

Best regards

Kim

[gmarsh]

the link (as before)

http://rapidshare.de/files/2470563/HD1.zip.html

works here... just scroll down to the bottom of the page, click 'free', and scroll to the bottom of the page. You'll see "Download ticket reserved: please wait xx seconds", and finally you'll see "Download: HD1.zip"

I'm compiling a parts list now.

[gmarsh]

Originally posted by kimschips
Have you thought about a group buy for the pcb or how can I order one from you if so?

Just one questen: I have an cdplayer with digital output with ligthwire and a RCA plug output.
How can I connect one off the digital output to your DAC input?

Best regards

Kim

A toslink (optical) cable will plug directly into the back of the unit. To plug into an RCA output, I use a 75 ohm BNC video cable with a *gasp* RCA to BNC converter.

I haven't considered a group buy. I'm just throwing this project out there for people to hack and tweak. Audiophiles tend to be an opinionated and emotional bunch, and I'm sure I've offended a few folks by using plain bridge rectifiers, non-snubbed capacitance after the rectifiers, hysteresis on the coax SPDIF input, ceramic capacitors in the audio signal path, a cheap clock oscillator, blah blah blah...

Though I might make a new "fix what's wrong" version of the PCB. There's a couple of mechanical issues I'd like to address - you have to "shave" the transformers, nibble the corner off the LM1085-3.3 and dremel some clearance into the 1455L1601 case for everything to fit... you can avoid all of this by using a taller case. Also the -12V regulator runs a bit hotter than I'd like. Changes will involve going to a 1.6VA transformer for the 3.3V/5V power supply, and replacing the LM1085's with surface mount TO-252 packaged regulators that heatsink to the ground plane. I might also make the 0603 jumper underneath the DAC into a PCB trace.

Tobias, you mentioned buying the PCB first so it's yours. I'll e-mail you later today/tonight.

[Porksoda]

I am DYING to know how you did input selection! I am getting started in AVR programming myself and I am building a DAC w/ multiple inputs right now. As far as I can guess from your schematic, you had each input go in as a different format, and then changed formats until one locked, is that correct?

How fast was that thing switching? I would think you would end up losing a few samples in the process when you first start.

[gmarsh]

Originally posted by Porksoda
I am DYING to know how you did input selection! I am getting started in AVR programming myself and I am building a DAC w/ multiple inputs right now. As far as I can guess from your schematic, you had each input go in as a different format, and then changed formats until one locked, is that correct?

How fast was that thing switching? I would think you would end up losing a few samples in the process when you first start.

I switch back and forth every 250ms until the CS8416 locks to something.