Hi @Keropi
From what I know, the Windows 3.x software have a nice help file that gives many information about the components and the signals. Maybe it is worth reading it, you can get a clue there.

I will check out the help file, thanks for the tip Datadrainer

edit:
I cannot seem to be able to locate any help file inside the 9x/3x driver package 🙁

Did you check the CD-ROM that comes with the card? It have the drivers + the applications.
Unfortunately I do not have my card anymore and I made no backup of the disc 🙁 There is no backup on archive.org, but VVDL have one for the 64S with the docs. The cards being similar in some points, I don't know, can work.

Edit: There is also the http://terratec.ultron.info/Audio/EWS/64XL/ archive that can have some interesting stuff to try to understand why this odd behavior is happening. Especially this file. In any case, good luck!

Did you try to reset the EEPROM to factory default with the tool EWS64NEU.exe?
As far as I remember there was also a mixer/ control panel available for windows. I think it was win9x. You can adjust the effects like reverb there. They might be stored in the EEPROM as well.

I will take a look again on these files Datadrainer - I did open the HLP files but I could not locate any info on effects , but then again they are in German so it's not 100% sure the info is not there

@JimWest
I looked at the eeprom tools, from what I understood these just update the CS4236 eeprom, all the settings and pnp configs in it are just familiar from orpheus...
maybe I am wrong but the SAM9407 configuration has nothing to do with this eeprom data. The init tool uploads a 9407 firmware and also mixer settings pre-saved from windows mixer (if present).
I will investigate more when I can , it's too weird behavior

That's something that struck me too when testing the card. The reverb/chorus effects are too pronounced which has surprised me as Terratec Maestro 32/96 is balanced perfectly. You have to change the values in the windows mixer and then save them into a file and load the file in DOS. Haven't have much time to test it though.

Sorry you can't find useful information on the files about the card logic. I remember using this card in the past and it was a good card with clear sound and no perceptible noise but I think I didn't use any MIDI modules with it (can't remember).
The card uses a lot a electrolytic capacitors but there is only a few near the SAM9407. I just took a look at it's datasheet and I didn't see any dedicated input to set anything as reverb or chorus levels, so it is set like the rest when programming the chip through the 16-bit data bus. Meaning it can only be controlled by the dedicated software. Looking at a photo, I can see the card uses quite standard chips (Philips and Texas Instruments branded for the most part) and I doubt TerracTec would have designed a way to initialize the SAM through an EEPROM and drivers calls from one to the other. I think apart from when the signals arriving in the mixer the SAM and the CM are two isolated things. For me look like an issue with the software. Did you tried different versions of the driver? Maybe there is a bug or a default misconfiguration thing here. Please, can you tell what is the result with older versions? Thanks.
Edit: Taking a closer look at the board, there is a square component with a sticker just under the RAM. At first I was thinking of a GAL, but as the SAM have everything to manage RAM and I/O inside, look like more an EEPROM to me. Do you have information about the chip?

Paar wrote on 2023-03-01, 08:18:

That's something that struck me too when testing the card. The reverb/chorus effects are too pronounced which has surprised me as Terratec Maestro 32/96 is balanced perfectly. You have to change the values in the windows mixer and then save them into a file and load the file in DOS. Haven't have much time to test it though.

yes this works perfectly!
there is a file called "EWS64_MixerSettings.exe" that holds inside several .MIX files
a peek inside reveals the file "NO_FX.MIX" which can be used with EWSINIT.EXE -M option (example: EWSINIT -F -V -B GSSBK320.94B -M NO_FX.MIX)
and that just kills the extensive reverb/echo effects that are applied by default.

I am attaching EWS64_MixerSettings.exe here in case someone else needs it in the future.

also a reminder for the future:
the card's drivers can be found on the EWS64 XL RETRONN.DE page , files located in this FTP link

Great 😀 So it was a software issue.
Thank you @keropi to tell us how the issue was solved and to @Paar for orienting the right way.
The FTP is most up-to-date than the HTTP "mirror" from my link. A backup should be made as FTP servers are shutting down one after another those days.
Please, can you tell me what is the square component I was talking about? I didn't find any thing about it on the Web. Thanks 😀

Datadrainer wrote on 2023-03-01, 10:16:

[...] Please, can you tell me what is the square component I was talking about? I didn't find any thing about it on the Web. Thanks 😀

sorry I missed this part
the square component is indeed a GAL , doing some address work for the SAM9407<->RAM interface
should be similar in function to the AWE64 SIMMCON addon - but it's just a guesstimate from my part so don't take it as an axiom 😀

keropi wrote on 2023-03-01, 10:41:

Datadrainer wrote on 2023-03-01, 10:16:

[...] Please, can you tell me what is the square component I was talking about? I didn't find any thing about it on the Web. Thanks 😀

the square component is indeed a GAL , doing some address work for the SAM9407<->RAM interface
should be similar in function to the AWE64 SIMMCON addon - but it's just a guesstimate from my part so don't take it as an axiom 😀

Thank you 😉
Never seen one in a such package though.

they do exist in both DIP20 and PLCC20 forms

Yep, I do know the 20-pin ones, can be found on some daughter-boards (WaveBlaster plug), but not the 28-pins ones. That is why I oriented my though to an EEPROM which I know can be found as PLCC28. But can be a GAL as PLCC28.
I'll check that latter.
For now what is important, is that you can play with this nice card 😁
A few years ago, as the walls does not extend with the objets I accumulated, I had to separate from some of my hardware including this TerraTec EWS 64XL boxed with all its content. That's sad, but this thread acted as a remembrance.

it is a good card but it's mostly suited for windows usage - much like the AWE series IMHO
the nice thing about that is the SAM9407 synth - but again IMHO after the X2GS got made these kind of synths are just curios
still a good card to have in collection! 😀