MIDI guru required - MIDI to TRS cable - advice request for Strymon Sunset

JMP220478

New firmware upgrade for Sunset / Riverside opens up MIDI patch management via TRS Expression socket - MIDI apparently carried over tip ..  ( from youtube posting ) 

 is the cable the same as in the Chasebliss Audio pedals?
REPLYstrymon4 days agoThe cable is actually the opposite orientation with the MIDI data being sent to our pedals on the TIP of the TRS cable like Empress pedals.

 I've tried to purchase official cable from Strymon direct ( total car crash service :-(  ) .. 

So looking to get a UK cable assembled but what would be the likely wiring config ? 

thanks for looking 

ecc83

MIDI data is "differential" that is to say it comes out of pins 4 AND 5 but of opposite polarity. The screen on pin 2 of the DIN plays no part in the operation.

I have not so far checked but logically the data would go on ring and tip, like a balanced audio cable.

Dave.

Teetonetal

The chase bliss faves box allows 7 presets for the strymon pedals. Joel posted a how to video on the chase bliss Facebook page.

JMP220478

ecc83 said:

MIDI data is "differential" that is to say it comes out of pins 4 AND 5 but of opposite polarity. The screen on pin 2 of the DIN plays no part in the operation.

I have not so far checked but logically the data would go on ring and tip, like a balanced audio cable.

Dave.

question - ex youtube posting 

Hey guys, could I hook up one of your drive pedals to the Meris MIDI I/O instead? Asking because I already have one of those.

Yes, Riverside and Sunset will communicate via MIDI with any TRS MIDI box that sends signals to the pedal on the TIP and receives signals from the pedal on the RING of the TRS connection.?

cable looks like this - but as said above - wont despatch to UK and not in Europe til late October 

https://store.strymon.net/midi-exp-cable

JMP220478

Strymon have now commented on the midi spec officially 

How do Strymon pedals send/receive MIDI messages sent via 1/4" TRS MIDI cable?

On our pedals equipped with a 1/4″ TRS MIDI connection (Riverside and Sunset), the MIDI data is received by the pedals from the TIP of this connection.  When MIDI OUT or THROUGH is enabled on these pedals, the MIDI data is sent out of the pedal from the RING of the TRS connection.

so should this be midi out  - pin 2 => TRS sleeve  ; pin 4 => TRS  ring ; pin 5 => TRS tip ?  

ManiacZero

JMP220478 said:

Strymon have now commented on the midi spec officially 

How do Strymon pedals send/receive MIDI messages sent via 1/4" TRS MIDI cable?

On our pedals equipped with a 1/4″ TRS MIDI connection (Riverside and Sunset), the MIDI data is received by the pedals from the TIP of this connection.  When MIDI OUT or THROUGH is enabled on these pedals, the MIDI data is sent out of the pedal from the RING of the TRS connection.

so should this be midi out  - pin 2 => TRS sleeve  ; pin 4 => TRS  ring ; pin 5 => TRS tip ?  

I emailed Strymon support about the Strymon MIDI Cable and asked them about the cable trying to find out if they adopted the MIDI DIN5 to TRS A OR B standard which basically flips the pins 2&3’s polarity on the TRS Tip and Sleeve respectively. What I got back was neither!  Strymon uses a proprietary cable. The support specialist attached this torn out drawing which is a schematic of the Strymon MIDI Cable.  So I ordered the cable. Cost more than your average MIDI cable. But I have not regretted buying it now. Here’s a link to a picture.  Sorry about what I used and the clarity:

https://imgur.com/gallery/Md24LCE?s=sms

There are 3 resistors, a diode, and a 6N138 high speed opto-coupler IC chip inside a cylindrical capsule. One might think it is a ferrite bead but it’s not. So if Strymon has gone to this length to make this cable, there must be something that is not either compatible or reliable using just a straight-thru wiring scenario. Usually this kind of circuit is used to mate different voltages or to keep down interference. So word the the wise over seas who can’t yet get this cable, order the parts and make one somehow. Maybe wire it up on an in-expensive breadboard at least. BTW - This is only for input to the pedal. 

I hope this helps. 

- MZ

JMP220478

@ManiacZero ;; - thanks for sharing - I mailed them too as they released slightly more information on the Sunset support page - it indeed looks like a busy cable and not just a simple wiring pin to jack conundrum .. 
I checked your location and of course you're in USA - I tried to order a cable to UK and they allowed order to process initially then hiked the postage costs and then ultimately said they didnt ship to UK ..  I gave them some structured feedback that they needed to sort their sales portal out !! 
Cable not available until mid october earliest - otherwise they suggested Empress Midibox2 as an alternative to cable ..
Issue for me is I'd ideally like to use short run cables and dont have pedalboard real estate to host the midibox or similar ..
Many thanks for sharing the schematic and information in general - one of the many positives of this forum is mutual support irrespective of location and timezone .. cheers 

Looking at diagram - if I am reading it correctly - this is  the return from Sunset to Midi In on for example a Timeline - is that how you interpret it ? 

JMP220478

This is what I got back from Strymon Support  when I asked about midi pin to TRS jack wiring 

We follow the same TRS MIDI scheme as Disaster Area and Empress. These do not simply wire the 5 pin DIN connections to the TRS; true MIDI data (post opto-isolator) needs to be sent into the pedal. TIP is MIDI IN, and RING is MIDI OUT.

Our cables here have an opto-isolator in line, and can let you send MIDI into the TRS jack:
https://store.strymon.net/midi-exp-cable/

Note that this cable is only one way, and won't let you get MIDI OUT.

Another way to do it would be to get some kind of MIDI box to split the signal from 5 pin DIN to TRS:
https://empresseffects.com/products/midibox2

https://www.disasterareaamps.com/shop/midibox

The Empress box is nice because one port is bi-directional and you could use MIDI OUT of the Sunset if you needed it.

ManiacZero

JMP220478 said:

Looking at diagram - if I am reading it correctly - this is  the return from Sunset to Midi In on for example a Timeline - is that how you interpret it ? 

Now that I look at the drawing closer, I think the DIN is actually mis-labeled at MIDI IN.  I pretty sure that should be MIDI OUT from like a Timeline or a MIDI controller.  Yea, that makes more sense. I’m an electronic technician for about 24 years. Since they refer to Disaster Area  and alike, and since this is also in essence just a two-wire circuit, the optoisolator is for preventing ground loops through the MIDI connections on each end.  Otherwise grounds would be connected from different devices and we are all familiar with that disastrous sound problem on pedal boards. Hopefully I answered you question:-)

ManiacZero

I actually went back and edited the post of the schematic on Imgur which reads:

”Strymon MIDI DIN5 to TRS Cable Schematic. Edit:  I believe this is mislabeled on the DIN as MIDI IN. Should actually be labeled MIDI OUT because signal is traveling from the MIDI Out of another device’s DIN or controller’s DIN to the TRS Exp jack on the Strymon Sunset and/or Riverside.  You could say MIDI data is flowing in the cable there but it is physically connected to a MIDI OUT   ”

-MZ

JMP220478

these two posts are quite interesting from the Empress site 

https://support.empresseffects.com/support/solutions/articles/1000229541-i-want-to-use-midi-with-your-midi-enabled-pedals-but-i-don-t-want-to-buy-the-midibox-what-are-my-op

https://empresseffects.freshdesk.com/support/solutions/articles/1000114016-i-design-build-guitar-effects-and-i-think-midi-is-rad-can-i-make-my-pedal-compatible-with-the-empres

first seems to contradict need for sophisticated cables

second is extremely open indeed .. 

JMP220478

ManiacZero said:

I actually went back and edited the post of the schematic on Imgur which reads:

”Strymon MIDI DIN5 to TRS Cable Schematic. Edit:  I believe this is mislabeled on the DIN as MIDI IN. Should actually be labeled MIDI OUT because signal is traveling from the MIDI Out of another device’s DIN or controller’s DIN to the TRS Exp jack on the Strymon Sunset and/or Riverside.  You could say MIDI data is flowing in the cable there but it is physically connected to a MIDI OUT   ”

-MZ

I did suspect this to be case but no specific electronics background other than simple guitar wiring / some electronic kit project assembly many many many years ago ... 

JMP220478

Re voltages involved - is there any specific danger of midi to trs jack direct connection ie no coupler / resistor network  involved ? 

as the simple midi pin to TRS diagram in this posting wasnt frowned upon by Empress 

https://support.empresseffects.com/support/solutions/articles/1000229541-i-want-to-use-midi-with-your-midi-enabled-pedals-but-i-don-t-want-to-buy-the-midibox-what-are-my-op

Also not sure exactly how to interpret this statement - midibox and midibox 2 are simple current to voltage converters - ? 

normula1

So that picture is basically the opto isolated input buffer that any MIDI device should have at its MIDI "IN" port.
The pic is therefore labelled correctly even if it looks counter intuitive as logically the buffer comes after the input socket (which is not physically present as its hardwired in the cable itself) and before any upstream electronics in the pedal.

robinbowes

ManiacZero said:

I actually went back and edited the post of the schematic on Imgur which reads:

”Strymon MIDI DIN5 to TRS Cable Schematic. Edit:  I believe this is mislabeled on the DIN as MIDI IN. Should actually be labeled MIDI OUT because signal is traveling from the MIDI Out of another device’s DIN or controller’s DIN to the TRS Exp jack on the Strymon Sunset and/or Riverside.  You could say MIDI data is flowing in the cable there but it is physically connected to a MIDI OUT   ”

-MZ

This is pretty much straight from the MIDI specification. It's describing the MIDI input of a device, ie. it depicts a 5-pin socket. From that perspective, MIDI IN is the correct label. You would connect from the MIDI output of another device into the MIDI input of this device.

Another giveaway that this is not a spec for cable wiring is that it's an active circuit, ie. the 6N138 requires +5v to operate.

R.

ecc83

The cables terminate in a 180° five-pin DIN connector. Standard applications use only three of the five conductors: a ground wire, and a balanced pair of conductors that carry a +5 volt signal

The posts had me worried but the above quote from Wiki shows that I am right in saying MIDI signals are "balanced".

The only kit I have seen (pictures of) that use 3.5mm jacks for MIDI have a had two, send and return, The optocoupler is there to prevent earth loops but I dare say it gets left out on some onf the gear?

Dave.

ManiacZero

Another way to better look at the five pin DIN as the MIDI Input that must be plugged into the Output of the controlling device.  

As for directly connecting without the optocoupler circuit (straight wiring or resistor network) I personally would not do it.

With that said, this is what I received from Hugo at Strymon:

Hugo (Strymon) 

Aug 30, 09:33 AKDT 

Hi Mark,

Thanks for supporting Strymon!

Our MIDI EXP cable can only send MIDI data to the pedals as they are not designed to receive MIDI back from the pedals using the same cable. MIDI OUT or THRU can only be achieved using a TRS cable plugged into a 1/4" MIDI breakout box that has support for receiving MIDI data back through the RING. (The Empress MIDIbox2 has a single jack with this capability.) The MIDI data is sent to the pedals through the TIP of the TRS connection like on Empress pedals.

I have attached a diagram of the MIDI EXP cable to this email.

Best regards,

Hugo Merida
Customer Support Manager
Strymon Engineering

JMP220478

Im most likely to stick out for proprietary cable - but super underwhelmed at timeframe to release to europe what looks like an outsourced low cost cable ..

I do have a question for those who care to chip in ..

scenarios to make this work 

Midi Out =>  passive Strymon Cable  ( midi to TRS ) => Strymon Sunset EXP jack   -  preset access 

Midi Out => Midi to Midi cable => Active Empress Midibox2 ( or similar ) => TRS to TRS cable  => Strymon Sunset EXP jack - preset etc 

So to me - uneducated electronics / MIDI etc  ; that the passive cable is fulfilling job of active MidiBox  ? 

as Strymon have said their cable carries diode / Optocoupler / resistor network  - where is current being carried from to power it ? 
I presume from MIDI out socket on send device or is it circuit formed when cable attaches both devices ? 

JMP220478

just watched above " 

MIDI for the Arduino - Circuit Analysis"  

 ( www.youtube.com/watch?time_continue=3&v=0L7WAMFWSgY )

 -   and now have I believe a better understanding ... I think 

Strymon  EXP method  - The way almost every expression pedal out there works is that it takes a reference voltage from the device it’s connected to, divides that voltage down by a certain amount and then feeds it back to the device. In electronic terms, this is most commonly accomplished with a TRS (tip / ring / sleeve) 1/4″ cable where the reference voltage is on the “ring,” the control voltage is fed back to the device on the “tip” and the “sleeve” is ground.

so in this diagram - https://imgur.com/gallery/Md24LCE?s=sms  ;  ( Strymon cable ) 

 - I make assumption that +5v supply fed from ring ?   therefore explaining how the active components in the Strymon proprietary lead are powered ? 

m10071978

Has anyone tested the reverse variant - controlling external FX module with Sunset? Is it possible with simple custom-built passive cable? (Ring and Screen to MIDI input of external module). 
Or may be official Strymon cable can be modified by re-soldering the wire from Tip to Ring?

JMP220478

sorry - cant help you on this one - I relented in the end and bought the official cable - I had disappeared down the midi rabbit hole for far too long ..