Yamaha THR10 Remote Foot-Switches Controller + Stereo SEND OUT - SEND IN Loop + External Balaced OUTPT

The THR10 YAMAHA is a great little amp (for me, so far, The Greatest) but doesn't have the Send/Return (Loop FX) connection...: this was my introduction to the project https://www.instructables.com/THR10-Effect-Loop-M... published 5 years ago!

Well, in the meantime Yamaha has issued the version II and... no Send/Return Loop feature yet, so I decided to publish the evolution of the original project (I recommend you'll have a look at it for all the theory...) with the adding of the Remote Footswitch Controller.

In summary, these are the new features for your THR10/5:

1. Send/Return connection for external FX Loop
2. Send/Return By-pass Switch
3. Remote Footswitch for Fade-Out and Fade-In (volume decrease and increase automatically)
4. Remote Preset 1 to 5 Footswitches
5. Remote Tuner Footswitch
6. Amp selection UP and DOWN Footswitsches
7. OLED Remote Display
8. External Balanced OUTPUT

...quite a lot!

1. Arduino nano x2
2. 1N4004 (or equivalent) x8
3. Ceramic Capacitor 330nF
4. Ceramic Capacitor 47nF
5. Ceramic Capacitor 0.1uF
6. Ceramic Capacitor 1uF x2
7. Electrolytic Capacitor 1mF x2
8. Resistor 10k x9
9. 7809 Voltage Regulator
10. SIP-IA05 Reed Relais 5V x8
11. MCP42100 Digital Potentiometer
12. OLED display 128x64 I2C
13. DIN5 female connector
14. RJ45 Ethernet connectors x2
15. 2-way slide switch
16. Footswitches Momentary SPST x9
17. External Passive ART Dual Z Direct Box

As recommended in the https://www.instructables.com/THR10-Effect-Loop-M... you need to have some basic skill to deal with PCB and SMD (Surface-Mount Device).

Finally I managed to use EAGLE: I can now attach proper schematics (and breadboard as well). So thanks to AUTODESK and fritzing for their Free version available for my MacBook Pro (Mid 2009)!

The "LOOP Schematic" here shows the connections needed on the THR10. With the help of the pictures you have to find:

1. the SMD capacitors C140 and C143
2. the switches SW602 and SW606 to SW611
3. the common connection of diodes D603, D604...
4. the +15V

The Capacitor C140 and C143 need to be removed in order to create an "OPEN LOOP" where you can introduce the External Loop.

The scope of the interface is to "simulate" the switches of the top panel to:

1. Recall the USER MEMORY Preset 1 to 5
2. Activate the TUNER
3. simulate the ROTARY encoder "AMP" to select from CLEAN to FLAT

Once the connections are found on the PCB the idea is to "double" the contacts with REED Relay Contacts in parallel: on the last step (Further Development) I have proposed a solution with CD4066 quad-switches but the relay option have been tested for more than 2 years and... still working!

The total number of connections are 10 so you can use a multiple cable to physically connect the ampli to the remote. I actually started with this approach and used the RJ45 as delmarvatriker has published on flickr (sorry, I have no other way to recognise your work!): the limitation of 8 contacts has pushed me to adopt a different approach.

So, the idea is to use 2 Arduino nano to communicate through a Serial protocol, in this way you have much less limitations and you just need one wire: in fact the project uses only transmit (TX) from the Remote-Arduino and receive (RX) on the Ampli-Arduino. The other RX/TX is connected just for future development.

On the RJ45 connector we need to wire as well +5V and GND: I proposed a connection that should work either with straight-through and crossover Ethernet Cable but be very careful and test the connection to avoid short circuit or dangerous connections!

The Arduino nano is in charge as well to activate the function FADE-IN and FADE-OUT.

I have used a digital double potentiometer MCP42100 that is acting as a stereo volume on the loop: once the command is received from the Serial on the nano, the potentiometers progressively reduce the volume.

Any other command will bring back the volume to max.

Finally you'll see the LOOP diagram with the DIN5 connector and with the new Bypass switch in case you don't want to use the external loop: please be sure you remove the external Loop jack when it is bypassed to avoid to overload the THR10 internal power amp.

The code is commented, I hope, in a way that should be easy to understand how it works...

The schematic of the Remote Footswitch is quite straightforward: 9 Momentary Footswitches connected through 9 pull-down resistors and an OLED display connected through I2C protocol.

This is the beauty to use Arduino nano to manage the remote communication!

The Serial signal is send (TX) at the pin 11 and received (RX) at pin 12: please note that I only use TX and, so you can even avoid to connect the pin 12 (and saving a wire)!

I have used a bended stainless-steel sheet with 10 holes, one of which for the OLED Display: although it seems very small in the pictures I found this display very readable and well integrated in the pedalboard.

...and you're right: I have used blu-tack to fix it and, after 2 years is still there!

At start-up the OLED display shows an image (you can upload your own https://create.arduino.cc/projecthub/najad/interf... ).

The THR10 stays on the manual setting until any of the footswitch are momentary pressed.

Please note that the TUNER switch doesn't need to be pressed for more than 2 second to activate the function: I believe that is handy to just press it momentary. Any other footswitch cancels the TUNER function.

The UP and DOWN foot-switches simulate the Rotary Encoder for the AMP selection: in the display I have added the "<" and ">" to show in which direction you are going.

Finally the FADE footswitch starts the FADE-OUT (progressive volume reduction) that can be cancelled by any other Footswitch or reverted to FADE-IN (progressive volume increase) if pressed again.

The video shows all the performances of the modification:

1. having the Send/Return Loop permits to play though a Guitar Looper (I have used the fantastic Boss RC-1 hacked https://www.instructables.com/RC-1-Loop-Station-B... ) to record a base with a preset and play over with any other preset!
2. turning ON the THR10 plays the manual setting and the Remote displays a picture of your choice (here is my little son!)

1. after I changed to Preset 1 to play some solo
2. then moving Down and Up through the AMP selection (sorry to have introduced some heavy metal stuff here...)
3. changing again to Preset 3 and 4
4. finally activating the FADE to fade-out
5. at the end using the one-shot press button for TUNING

Not bad!

...except probably the quality of my playing: some mercy for me!

These are the things that could be done better:

1. better C+ code
2. use the TX-RX communication to confirm some status from the THR10 to the remote Display or to change some parameters like the the time of FADE-OUT...
3. if you only use TX (as actually has been done in this project) you don't need a RJ45, you just need 3 poles connector for +5V, TX, GND. This can simplify the hardware installation! Anyway I left the ethernet connection for the high availability of cables and for the compact size of the connectors and... because was my first attempt to make a remote foot controller!
4. instead of nano I could use nano 33 BLE to have Bluetooth: yes but, you still need to power supply the remote unit so I decided that is pointless to have wireless communication and a wired unit to the power!
5. I have used this SIP-IA05 Reed Relay that are very "prototype" style and never moved to a more "elegant" solution. I have attached a possible one using CD4066 (not tested).
6. for FADE function could be an option to use the Guitar Volume potentiometer on the THR10 (VR11). I have attached a possible schematic but I haven't tried yet.
7. All the circuit has been made with PCB prototype: I believe it's possible to do a nice job with a proper Arduino nano shield PCB, especially using the CD4066. Someone can make a small business selling the kit... well, don't forget to send me one!

The internal logic of the THR is to activate the Headphone Amp AND de-activate the Power Amp. I have tried to "cheat" removing the activation signal but didn't work (also the Power Amp has been disable).

The way I have used to have a quality stereo balanced output to PA is "all external" and is using a stereo Passive ART Dual Z Direct Box (but any passive stereo direct box works - I have used ART because is cheap and high quality):

1 - connect the SENDs of THR10 to the IN of the stereo Looper (in the picture the Ditto x4 TC Electronic)

2 - the OUTs of the Looper to the INPUTs of the Passive Direct Box

3 - the THRU OUTPUT of the Direct Box to the RETURN of THR10 Loop

4 - the BALANCED OUT's of the Direct Box to the PA

If you don't need a Looper you can connect directly the SEND of the THR10 to the INPUT of the Direct BOX...

I have made a dedicated cable as well (you see it in the picture and in the schematic) to have a MONO output, simply connecting the to output transformers of the ART in series: it works very well but, of course, stereo outputs preserve the beauty of THR reverb!