• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KHz

Disabled Account
Joined 2005
Is there a list of all of the umanager commands someplace in Soekris land? Specifically looking for input selection and sample rate. Or a reboot command so I dont have to power cycle. I have looked and no signs. Thanks!

Input selection is not done in uManager!
If you are in uManager type exit to get out of it. the DAM will respond with nothing.

To select inputs type Ix and return, where Ix is one of:

I0 = I2S
I1 = SPDIF 1 (this will be coax)
I2 = SPDIF 2 (typically TOSLINK)
I3 = auto select, scans for active inputs.

The trap here is the Ix does not respond to the first input, so you need to enter it twice to get anywhere. Once the DAM responds you only need to key it once.
I've discovered you can type the two input commands without any pause and the DAM responds to the second one.

**** Tip ****
If your terminal program supports macro's it is a good idea to assign them for commonly used functions.

I've got ZTerm macro's set up with:

command-1: I0
command-2: I1
command-3: I2
command-4: I3
command-5: +++
command-6: download
command-7: exit

This means my filter download process is:
command-5
command-6
command-S (send file keyboard short cut)
command-7
command-4 (ignored)
command-4 (this causes DAM to scan inputs and reloads filters in the process)

Once I hook up the adapter it takes around 30 seconds to upload and activate a new filter. No power cycle required.

**** end tip ****

You cannot select sample rates manually.
The DAM locks to the sample rate of the incoming data on the selected input.

In uManager you can get a list of commands by typing "?"

Code:
# ?
uManager Commands

?/Help               show this help
set par=value        set paramter to value, set alone to show
exit                 exit uManager
update               update uManager firmware
download             download and update system flash
idf                  show ID of flash
df [adr]             dump flash content

#

Type "set" to see the configured settings. It only shows volume preset and baud rate for comms.

The only thing you need to power cycle for is firmware update. I'm sure you can manage that manually given the frequency of firmware updates ;)

cheers
Paul
 
Last edited:
Input selection is not done in uManager!
If you are in uManager type exit to get out of it. the DAM will respond with nothing.

To select inputs type Ix and return, where Ix is one of:

I0 = I2S
I1 = SPDIF 1 (this will be coax)
I2 = SPDIF 2 (typically TOSLINK)
I3 = auto select, scans for active inputs.

The trap here is the Ix does not respond to the first input, so you need to enter it twice to get anywhere. Once the DAM responds you only need to key it once.
I've discovered you can type the two input commands without any pause and the DAM responds to the second one.

**** Tip ****
If your terminal program supports macro's it is a good idea to assign them for commonly used functions.

I've got ZTerm macro's set up with:

command-1: I0
command-2: I1
command-3: I2
command-4: I3
command-5: +++
command-6: download
command-7: exit

This means my filter download process is:
command-5
command-6
command-S (send file keyboard short cut)
command-7
command-4 (ignored)
command-4 (this causes DAM to scan inputs and reloads filters in the process)

Once I hook up the adapter it takes around 30 seconds to upload and activate a new filter. No power cycle required.

**** end tip ****

You cannot select sample rates manually.
The DAM locks to the sample rate of the incoming data on the selected input.

In uManager you can get a list of commands by typing "?"

Code:
# ?
uManager Commands

?/Help               show this help
set par=value        set paramter to value, set alone to show
exit                 exit uManager
update               update uManager firmware
download             download and update system flash
idf                  show ID of flash
df [adr]             dump flash content

#

Type "set" to see the configured settings. It only shows volume preset and baud rate for comms.

The only thing you need to power cycle for is firmware update. I'm sure you can manage that manually given the frequency of firmware updates ;)

cheers
Paul

Haha no worries on the firmware :rolleyes:
Thanks for the tip that will save tons of time!
 
Last night I took my DAM and headed out to a good friend of mine to do some listening tests.

My DAM at the moment is powered by a Salas BiB at 12VDC. It has a DIYINHK XMOS based USB to I2S receiver powered by a Salas Reflektor-D at 3.3VDC. The same supply powers the isolated side of the DAM.

The first objective was to assess the importance of a good DC power supply instead of a plain transformer. In order to do that I took with me an extra 50VA toroidal with 2 x 7V windings.

My friend's system consists of Magnepan speakers, a DIY fet-based preamp and DIY power amp (solid state, 60KG monster). It is widely regarded as a very revealing and non-forgiving system. Any change in any of its components (or a component withing the components) is clearly heard.

The DAM was connected to the preamp through its unbuffered outputs.

We gave the system some time to warm up (it was probably a couple of hours) and then sat down to listen. We started with the DAM as it was, with the Salas BiB. We then unplugged the Salas and hooked up the plain transformer.

The change was immediately obvious. The sound thinned, it became more harsh in the high end. It also lost resolution and detail. Going back to the BiB made all the good qualities come back.

Thus, I can definitely recommend a proper DC power supply for the DAM. I cannot say whether it was the Salas that did the work or that any DC power supply would do the same, but the improvement was definitely there. Note that I have the BoM for the Salas BiB I built in my blog.

The second objective was to assess the difference that could be made by using a "proper" output stage after the unbuffered outputs.

So I built a pair of AMB alpha20 line amplifiers. I set their gain to 2 and powered them temporarily by the same Salas BiB that powers the Soekris.

Note that my DAM outputs roughly 1V RMS at its output @ 0db since I'm using a filter that includes attenuation at FIR2 (I can't really remember which one it is though..). This meant that the alpha20 brought its output to a nice 2V RMS.

Going back and forth between using the alpha20 and just the unbuffered outputs, the conclusion was that the alpha20 removed a small amount of the "magic" of the DAM while not really helping in anything besides output volume. I was hoping that it would help improve the dynamics of the DAM - its Achilles' heel IMHO. In my friend's system the DAM sounds "flat" compared to his other sources (a heavily modified Sony 50ES cdp, a Buffalo 3 DAC, and an Aune S16). However, this "flatness" is not particularly obvious in other more forgiving systems.

So, my assessment of the DAM so far is as such: It has great detail, exceptional mid-range, adequate bass, it is a little soft on the highs, but its main problem is the dynamics. It can sound a bit "flat", with this quality either accentuated or minimized, depending on the rest on the system.

If there was a way to improve its dynamics, to make it more "aggressive", it would be a stellar performer (with a proper DC power supply of course). As is, it is just great VFM.
 
Disabled Account
Joined 2005
Note that my DAM outputs roughly 1V RMS at its output @ 0db since I'm using a filter that includes attenuation at FIR2 (I can't really remember which one it is though..).

It will really depended on which filter you had installed. The first few versions of the attenuated FIR2 were basically tests to see if the attenuation made any noticeable difference to high volume harshness. There could be a range of FIR1 filters including at least one that is rolled off well into the mid-range.

The CRaPMagic linear phase would probably be one of the better choices, as this has a smooth roll-off FIR2 with 3dB attenuation, and the FIR1 filters sound pretty good imo.

It could also be worth having a listen to the DTYWP filter, as it has a later revision of the FIR2 (with 3dB attenuation), and doesn't have any significant roll off until 17kHz.
 
Implementation is going to account foir at least 50% of the performance of any DAC, even one like the DAM where at first glance it appears to be a finished project.

hi barrows,
i have already bought the Sonore usb - i2s with idea in my head to use 8x osf. Hope the result will be nice...

Personally I want to see a two board balanced implementation, with a fully isolated USB interface, separate shunt regulated power supplies, a really good FET or Tube output buffer

Could you explain more detail, what you mean by two board balanced implementation? what is the connection diagram?
 
well...

hi barrows,
i have already bought the Sonore usb - i2s with idea in my head to use 8x osf. Hope the result will be nice...



Could you explain more detail, what you mean by two board balanced implementation? what is the connection diagram?

I think Soren will have to provide the details of how to implement a true balanced version with two boards. It should be possible, but may also require a special software version from him as well.