Brief Odac impressions

Got my JDS Labs Odac board a few days ago.

It IS tiny, albeit very nice construction.

What chaffs my hide is the lack of instructions to install an output jack.

Jack part number and supplier would be nice, and there is the doubt about

the solder pad bridges underneath that lead from the line-out traces/pads.

Does one solder in resistors, if so what value? Or does one bridge them with a blob of solder?

Or maybe forget about them, and leave them alone?

Also the negative pads for the line out are not clearly marked.

If one is handy with a DMM, you could check for ground-plane & trace continuity I guess.

Still I think that a simple instruction page should be included for the end user if the builder is going to leave components off.

Or maybe I am missing something here? Could this info already be posted somewhere?

Anywho, Ima gonna solder it up and box it as I see fit, cant wait to hear the wunerful music! 

Thought I'd add - on the plus side, the JDS Labs offering includes the oddball USB cable with the mini-B connector.

Just wish they would mention it in their product offering, I almost went out and bought one while anticipating delivery of my Odac.

The Canadian distributor offers the Odac with a USB cable AND the 1/8 inch mini jack (not soldered to the board).

Edit - added the following:

Just fired the Odac up. What the OP said. Well worth the price of admission.

Good sounding unit, gonna need more time with it to form impressions.

I am comparing it to the HRT MS2 and MS2+ DACs, running a STAX SRS-2050 system.

I'm listening to my new ODAC that I installed this afternoon in one of my O2s.

The install is not plug and play.

The ODAC board fits in the place of the batteries as designed.

The wire routing between the ODAC and O2 board takes a bit of

head scratching. The O2 amp board wasn't designed for easy

plug and play connection with the new ODAC. You have to pick up 

Left-Right-Ground from underneath the O2 board under the input jack

and route the wires to the top side of the amp board. I ended up routing

3 runs of 24g navships wire squeezed through the pcb lead holes for P1.

I cut the input jack traces as described in Voldemort's blog and the

switching between input jack and onboard ODAC works as expected.

My WinXP desktop recognized the ODAC as "odac" and configuration

went quickly. Nice that the USB interface was programed to identify

itself to Windoze as "odac' rather than "USB audio device" like every other

DIY DAC project I've done. Downside is that ASIO4ALL won't play

through the ODAC. It may take some software fiddling to get it to work.

I have no problem with ASIO4ALL playing with a AMB y1, y2, grubDAC

or Alien DAC, so the ODAC is a bit different.

I've been listening to the ODAC for a couple hours now. So far I'm using

HD800's and playing mp3s CD rips, mostly 256kb and 320kb so no

higher sample rates or bitdepth. So far nothing jumps out audibly, either

pro or con with the sound. I'm looking forward to comparing it with my

other DIY dacs; I have a TP buffalo, buffalo II, amb Y1, Y2, and a GrubDac

to compare it to. Eventually I plan to install the ODAC line out jack and 

then will be able to run it through the paces using other "higher end" amps. 

 I'm not the most golden eared listener though and have

a difficult time telling any difference between the DAC's I have.

Quote:

Originally Posted by bada bing 

I'm listening to my new ODAC that I installed this afternoon in one of my O2s.

 

The install is not plug and play.

The ODAC board fits in the place of the batteries as designed.

The wire routing between the ODAC and O2 board takes a bit of

head scratching. The O2 amp board wasn't designed for easy

plug and play connection with the new ODAC. You have to get pick up 

Left-Right-Ground from underneath the O2 board under the input jack

and route the wires to the top side of the amp board. I ended up routing

3 runs of 24g navships wire squeezed through the pcb lead holes for P1.

I cut the input jack traces as described in Voldemort's blog and the

switching between input jack and onboard ODAC works as expected.

 

...snip

For the input, you can directly solder to the P1 pad through holes (Ground is the center).  There's no need to solder to the underside of the input jack on the O2.

Here is the PN for the output jack...

3.5mm Digikey CP-3523SJCT-ND

its also being sold on the JDS Labs site...

Seems the offical site for the ODAC is at diyaudio.com   then search for ODAC...   the boards are just now shipping...  

JDS is also selling a housed version... so it works with any amp...  looks good... 
 

Quote:

Originally Posted by shadow419 

 

For the input, you can directly solder to the P1 pad through holes (Ground is the center).  There's no need to solder to the underside of the input jack on the O2.

If you wire directly to P1 pads, the ODAC is hard wired to the input of the amp all the time.

If you wish to have the input switch built into the input jack socket function, i.e jack in an

external source disconnects the ODAC, jack removed connects the internal mounted ODAC,

then you must cut the traces and wire to pins 3 & 4 on the underside of the O2 pcb

for L & R out of the ODAC.

If you wire the ODAC directly to P1, a potential problem is if you connect an external source

and forget  and also have the ODAC powered and playing as well. This wires the

outputs of the two sources directly together. The two sources

will "fight" and over draw current from one or the other with potential damage.

So yeah, you can wire to P1, but I wouldn't do it unless the O2 amp is wired as a

ODAC amp only. Murphy's law will eventually bite you otherwise.

It's set and forget unless you actually have stuff above 44.1 since it won't resample stuff at the SR you set the shared mode to.  If you have a mix of 44.1 and 96 (the USB chip won't do 88.2) then you can just let foobar/WASAPI take care of the SR.  If you've got stuff at 88.2 then you'll need a good resampler like SoX but something like 99.9% of digital music is in 16/44 so it shouldn't be that big of a deal to most people.

Also disabling the volume control would be a waste since the whole point of a 24 bit DAC chip was to allow headroom for digital volume control.  The Win7 SRC does still suck but the 32 bit FP volume doesn't hurt anything.

Quote:

Originally Posted by bada bing 

If you wire directly to P1 pads, the ODAC is hard wired to the input of the amp all the time.

If you wish to have the input switch built into the input jack socket function, i.e jack in an

external source disconnects the ODAC, jack removed connects the internal mounted ODAC,

then you must cut the traces and wire to pins 3 & 4 on the underside of the O2 pcb

for L & R out of the ODAC.

 

If you wire the ODAC directly to P1, a potential problem is if you connect an external source

and forget  and also have the ODAC powered and playing as well. This wires the

outputs of the two sources directly together. The two sources

will "fight" and over draw current from one or the other with potential damage.

 

So yeah, you can wire to P1, but I wouldn't do it unless the O2 amp is wired as a

ODAC amp only. Murphy's law will eventually bite you otherwise.

If you look at the schematic, you'll see that wiring to P1 is the same as wiring to the underside of J2.  You cut the traces if you have J2 installed in order to defeat the input mute when nothing is plugged into J2.

No, wiring to P1 are the same connection as wiring to pins 2 & 5  of the switched

jack J2. Connecting this way hard wires the the ODAC connection to the same

traces as the external source input of J2. If you wire it that way and try to run the

ODAC simultaneously with an external source plugged in, it will do exactly as

I posted; the two sources outputs are hardwired together.

The J1 jack socket has a two pole switch function that "breaks" upon insertion of

a Jack and "makes" on withdrawal of a jack. Before the traces on the O2 pcb

are cut, when the J2 switch poles "make" on jack withdrawal, the switch shorts

the amp inputs to ground. If you wire the ODAC to P1, you must cut the traces

to keep the ODAC outputs from being shorted to ground when no jack is plugged

in, but P1 is wired directly to pins 2 & 5 of the jack - which are the external source

input leads.

The "correct" way to wire the ODAC is as I have post - connect to J2 pins 3 & 4

located on the underside of the O2 PCB under J2. And cut the traces, which is required

in any case. Wiring this way insures that there is no possibility of two sources outputs

wired together. This isn't something I've made up, it is mentioned on Voldemort's March

blog post about the ODAC (which is not allowed to link here). Perhaps Voldemort

will post detailed ODAC installation soon which will clarify the details better than I'm able. 

O2 INPUT SWITCHING: Those who only want a USB headphone DAC

(like the FiiO E10 or NuForce uDAC-2) can simply wire from the output

header of the ODAC to the P1 input header on the O2 board. But for

those who still want to use other sources (like an iPod, etc.) with their O2,

you can have your cake and eat it too. Once you cut the traces shown

to the right you can wire the ODAC to terminals 3 and 4 of the input jack.

These lead to internal switches in the jack and will connect the ODAC

only when nothing is plugged into the O2.

Stand corrected.  I misread what you wrote and and didn't realize you were talking about wiring to pins 3 & 4.  I though you were just cutting the traces to these pins.

Eagerly awaiting the arrival of my standalone ODAC.  I wanted to be able to use it with my other amps and not just my O2.