Studio Electronic SE-1 external input

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Studio Electronic SE-1 external input

Postby logix » Fri Mar 03, 2017 1:40 pm

I'm trying to add the external filter input modification to my Studio Electronics SE-1 but I'm unable to REPLACE the SE-1 noise source with the external input; instead I get the two sound sources at once. This isn't the way it's supposed to be, is it?

There used to be a "how to" page over at Syntheasy, but it's long gone. It's available at the Internet archive but unfortunately has most images missing which makes it useless.
Fortunately I kept a PDF archive of that page so I have everything intact. Here's the section about the filter input. Does it look right?
Image
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Re: Studio Electronic SE-1 external input

Postby logix » Fri Mar 03, 2017 6:54 pm

Never mind, I figured it out myself!
There was a shortcoming in the above instructions, but now the internal noise is cancelled when external input is applied as expected.

If there's any interest I can post instructions here on this and the faster ADSR attack modification as well.
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Re: Studio Electronic SE-1 external input

Postby DigitalMetal » Sun Sep 10, 2017 10:21 am

logix wrote:Never mind, I figured it out myself!
There was a shortcoming in the above instructions, but now the internal noise is cancelled when external input is applied as expected.

If there's any interest I can post instructions here on this and the faster ADSR attack modification as well.


Very cool, yes I'm interested please!
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Re: Studio Electronic SE-1 external input

Postby logix » Thu May 03, 2018 9:24 pm

I'm the OP and just read your reply. Hope this is still of interest.


Adding an external filter input to the SE-1
If your SE-1 didn't come with a factory-installed "External input" on the back panel (right next to the audio out jack) you can easily add an external filter input jack yourself. My SE-1 was missing this feature but there was an unused hole in the back for the socket. I don't know if this is standard on all of them, but if not you might need to drill a hole for the socket yourself.

An external sound source will replace the SE-1 noise generator (as long as the jack is inserted). If you remove the jack then normal operation (you can hear the SE-1 noise generator again).
This is how you use it:

  1. (within the SE-1 menus) adjust the "noise level" until you hear noise when pressing a key
  2. You may also need to adjust the ADSR envelope (so it doesn't fade out too quickly etc)
  3. Insert a 1/4" jack with the audio source (any audible (line-level) source: CD, tape, mic (through a preamp), another synth, sampler, drum machine etc.)
  4. Press a key on your MIDI keyboard as this will let the external sound through and let it get shaped by the SE-1
  5. Disconnect the external audio source jack on the back of the SE-1 when you want to use the synth normally again (using its own noise source)



Here's a schematic I made of the external filter input:
Image

The details are a little fuzzy so long after the fact but here are a few things to keep in mind:

1) use a 1/4" switched jack socket (normally closed) as you see in the schematic.
By "normally closed" I mean that without a jack inserted the circuit will work just like before, completely unmodified.

2) the filter socket's GND wire attaches to the GND pin of the existing output socket (purple wire in photo below)
Image

3) desolder one end of resistor R300 (16.9K) in order to solder the socket in between (see photo to ensure you lift up the correct end)
Image


I believe that's about it for the external filter input. Go ahead and try it out! Follow the instructions above if you don't know how.


Improving the attack rate of the SE-1
Compared to a Minimoog, many people find the ADSR attack rate of the SE-1 rather slow. The following modification involves replacing a resistor with a different value and should improve on this.
If this still isn't good enough there's a further thing you can do. I found the following info in the comment section of an SE-1 user review:
I inverted envelope #1, and used the envelope amount knob to gain the desired amount of punch. If you own an SE-1 and have experienced the same problem, give it a try.




a) gain access to the processor/memory/MIDI/control board (found underneath the analog board as shown here):
Image

b) locate R42 (original value 220K) and replace it with a 47K resistor as shown here:
Image


Backup battery replacement
If it's been a while since you changed the battery, and while your SE-1 as already open, go ahead and replace the memory backup battery (BR-2330). I believe synth memory batteries generally last for around 5 years (even though they often last a lot longer).
Make sure you sysex dump its existing memory first!

NOTE: I'm sure you could also use the more commonly available "CR" type (CR-2330) but the "BR" type is specified to handle a higher temperature (synths can get hot inside), has a lower discharge rate and a longer shelf life than the "CR" equivalents, so I would go for that. You might have to look up a more speciallzed store for it though (electronic component dealer etc.) as most corner-stores, supermarkets etc. only have the "CR" version.
Last edited by logix on Fri May 04, 2018 12:34 pm, edited 13 times in total.
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Re: Studio Electronic SE-1 external input

Postby DigitalMetal » Thu May 03, 2018 9:43 pm

That's fantastic thank you very much I really appreciate it!
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Re: Studio Electronic SE-1 external input

Postby logix » Fri May 04, 2018 10:31 am

DigitalMetal wrote:That's fantastic thank you very much I really appreciate it!


I'm glad you like it and you're still here to read it. Sorry about the long delay -it appears sometimes I'm not alerted about new postings.

Be sure to re-read my guide as I've just edited both the text and photos so things should be a lot clearer now :)

Let me know how your modifications goes, and please do tell if any of the details in my guide are incorrect. As I said; it's been a while.
Also, if any of the switches are misbehaving or the pots are getting scratchy/noisy I have info on how to repair those as well.
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