How to load custom filters for Soekris DACs

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by tommytakis, Dec 11, 2020.

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  1. tommytakis

    tommytakis MOT: E.T.A Headphones

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    I originally wrote out this guide for @Gaspasser back when he had the 1541, but since the new 2541 is out now and I thought I share this little guide I made with the community. The process is pretty simple but the information is so spread out all over the web. Purpose of this guide is to simplify all the steps w/ visuals for dummies like me. To my ears, the custom filters sound much more engaging than the ones that come stock with the DAC, but YMMV

    Helpful links:
    Soekris Audio ApS, Downloads
    Soekris dam 1021 R-2R DAC ILLUSTRATED GUIDE | H i F i D U I N O (wordpress.com)
    randytsuch's audio page: Soekris R2R Dam DAC (randytsuch-audio.blogspot.com)

    1. So first you need to find yourself a TTL cable:
    https://www.amazon.com/gp/product/B00QT7LQ88/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
    This one works and it's cheap.

    **updating filters and updating firmware is essentially the same process, you're just uploading files onto the DAC.

    2. Download Tera Term from the Soekris download page. (Randy's blog uses extraputty but I found Tera Term is simpler to use.)

    3. download the Firmware from soekris's website / Filter pack from DIYaudio forum. I'll be using the filter pack made from TNT on post #1833: Filter brewing for the Soekris R2R - Page 184 - diyAudio

    4. Open up the DAC unscrewing the 6 bottom screws and plug in the TTL cable into the 3 prong on the DAC here:
    [​IMG]
    IF you are using the TTL cable that I linked, this is how you attach them:
    red 5v -> Leave unconnected
    black lead -> GND
    green lead -> RXD
    white lead -> TXD

    5. Once connected, you need to now configure Tera Term so you can start uploading. Open Tera Term and select the right COM. COM# will differ from computer from computer but the right one will say something like "USB-to-serial Comm..."
    [​IMG]
    Then press OK

    6. Then do "setup" -> "serial port" -> then set "Baud rate" to "115200", "Data" should be "8", "Parity" should be "none", "Stop" should be "1", "Flow control" should be "none", once you make sure everything is good then click "OK".

    7. Now go to the command prompt and press "+++" if you did it right, this will show up on your screen
    [​IMG]
    you see how mine says Rev 1.20. that tells you which version I'm running. The current version is 1.21 so that tells me it's not up to date.

    8. Now type "download" then select the update file/filter pack you want. Once selected, it'll start uploading the file onto the dac.
    [​IMG]
    9. When done downloading type "update" and then when they ask "are you sure?" you type "y"
    [​IMG]

    10. Now you write "exit" and power off the dac for a couple seconds and restart the DAC. When you connect to Tera Term again, it should say the correct revision 1.21.
    [​IMG]
    11. ENJOY MUSIC

    **if any part was confusing, maybe other friends can fill in the gaps and make the guide even better. I don't own a soekris DAC anymore so I'm not sure how much more I can be of help, but hopefully this will suffice for the lot of you**
     
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  2. GoodEnoughGear

    GoodEnoughGear Evil Dr. Shultz‎

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    Actually DAC2541 has a serial interface built in and you update via USB - no need to open it up:
    Firmware Upgrade: The dac2541 support firmware upgrade via the USB interface, which have a
    built in Serial Port function. The instructions are at http://soekris.dk/update_dac1xxx.html, but
    ignore step 1 and step 4 as the dac2541 have the built in Serial Interface. You use the same USB
    interface and cable you use for Audio.
     
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  3. Biodegraded

    Biodegraded Friend

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    A bit more info for firmware updating on pre-dac2541 models under Windows...

    If at step 5 of Tommy's guide above, Tera Term (other emulators might behave a bit differently) won't let you select 'Serial' in the 'New Connection' screen, you probably don't have a driver on your computer for the USB-to-serial cable.

    If using the FTDI cable referred to on the Soekris firmware update instructions page, with black, yellow & orange leads, locate the right driver for your operating system at https://www.ftdichip.com/FTDrivers.htm .

    If using a cable similar to the one linked by Tommy with black, white, green & red leads, it'll likely have a chipset that's a copy or ripoff of some version of the Prolific Technology PL-2303. The link says that one is compatible with Windows 8 so it should be ok with the current drivers at http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=223&pcid=126 .

    However, there are cables still being sold with earlier versions of PL-2303 that are not supported by Prolific and won't work with the current drivers. When you try to select the serial port in the terminal emulator, These will give rise to an message on the New Connections screen saying something like "NOT SUPPORTED SINCE 2012" and an error will be generated when you click OK.

    If you have one of these latter cables, supposedly compatible drivers are at http://www.ifamilysoftware.com/Prolific_PL-2303_Code_10_Fix.html (various Win versions) and https://github.com/johnstevenson/pl2303-win10 (Win 10 only). Installing one of these should allow the system to see the cable and for firmware/filter updates to proceed as described above and on the Soekris support page.
     
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  4. Noodlz

    Noodlz Almost "Made"

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    Oh wanted to chime in here in case anyone makes the same mistake as me. At step 7 to get into the uManager, don’t press enter expecting it to be a command, just type in +++ at regular speed and wait a sec after and you’ll get in.

    I make the rookie mistake of typing really fast and pressing enter, thinking that something broke when nothing happened after. Took me a good while before I realized my mistake
     
  5. Arun Kumar

    Arun Kumar Friend

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    @Noodlz Just curious, are you loading new filters for 2541? If so, which one? And where are you getting them from?
     
  6. Noodlz

    Noodlz Almost "Made"

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    Ah this is actually for the 1321, but I think it’s the same for the 2451. (Actually it’s even easier I think, you can use the usb in the 2451, in my 1321 I have to open it up and connect by a TTL cable)

    I loaded the tnt filter set from diyaudio, pg92 post 1833. https://www.diyaudio.com/community/threads/filter-brewing-for-the-soekris-r2r.269776/page-92

    i
    actually like the F5 setting “HQEQ” the best. I keep going “wow” or “damn” every time I listen. I also like the no filter, it’s more mellow. The HQEQ was a little hard sounding in the beginning but it’s waaay better now after being on for a few days.
     
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  7. Arun Kumar

    Arun Kumar Friend

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    @soekris Just tried to upload TNT filters as suggested earlier by Noodlz in my Soekris 2541. When I type `update` in terminal I'm getting confirmation prompt. Pressing 'y' then throws an error with a strange message about selecting an incorrect image!
     
  8. Biodegraded

    Biodegraded Friend

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    For those tempted to try the custom filters but who aren't DIYAudio members: since the recent DIYAudio site refresh, downloads don't require a membership, so no need to sign up any more.
     
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  9. soekris

    soekris MOT - Soekris Engineering

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    the "update" command is when you update the uC firmware.... You don't use it when downloading filters.
     
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  10. Noodlz

    Noodlz Almost "Made"

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    yep i was confused for a long while too.. from what I recall, in uManager you use "update" when you want to update the firmware, but you type "download" when you want to download the custom firmware into your DAC. For both you'd need to type the command, then use the UI and go into the menu for "transfer" and transfer the .skr custom filter pack file from your computer to the DAC.

    I'd confirm the following steps but I'd have to open my unit up again lol. That's one of the nicer thing of getting the newer 2451, you can just plug a USB in instead of having to use the TTL cable.
     
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  11. Arun Kumar

    Arun Kumar Friend

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    I think I managed to upload the skr file and rebooted soekris. I was expectingthe `filter` command would give a completely different output, but it's just changing the first line. I am not sure if something changed, and if so what exactly. Sadly my amp is with a friend on a loner and I'm using a different amp where I'm unable to make out any sonic difference :)

    Without uploading filter output of `filters`
    Original-filters list.png


    After uploading the skr file and rebooting soekris this is what I see. I was/am assuming that each of these 4 lines in filters correspond to different colored lights when I press the filter button. Based on that I was expecting all 4 lines to be different. It looks like only the first line is different after I changed the filter. Man this is hard!!

    DIYA_1021filt_noDCmode.skr-ScreenShot.png


    Update: My current interpretation is that `filters` command shows the `active` stack of filters in the dac.
    We have control over only the first filter in the stack and we could pick one of linear | mixed | minimum | soft (by setting value directly or by pressing the filter button).
    So the stack of filters stays as is and internal meaning of (linear | mixed | minimum | soft) is changed based on skr file.

    [Edited for more clarity]
     
    Last edited: Dec 30, 2021
  12. daduy

    daduy Rando

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