Bypassing Rotary Switch on Boss DD-2

[philrob1]

Hi all,

How might it be possible to bypass the S/M/L switch on the DD-2 so that the Delay Time controls the entire sweep from short to long?

DD-2 schematic for reference:

http://www.8bitsindgenug.net/boss_dd2.png

I'm looking to integrate the DD-2 into a multi-FX board and think this would be a nice feature.

Thanks in advance

Phil

[r080]

Welcome to the forum!

From the schematic you posted, it looks like the delay time pot controls a NAND gate VCO, which is fed directly into the microcontroller's clock input. The SML switch is input separately to the chip, and likely is used for some sort of clock divider.

The microcontroller RDD63H101 could potentially take different speeds, so an external clock with a wider range might work. The schematic says the clock range is 1.28MHz-5.18Mhz. This probably not the best idea.

You might be able to adjust the clock low and high trims and hardwire the switch to the middle position to see if that gives a usable range for you.

http://www.synfo.nl/servicemanuals/Boss/DD-2_DD-3_SERVICE_NOTES.pdf

One feature that should definitely be possible for the DD-2 is adding a switchable capacitor to the feedback loop to tame the highs.

Also, consider building a PT2399 delay like the Hamlet or Deep Blue delay. You might be able to find one smaller than a DD2 board that would fit better in a multipedal.

The Pete Cornish TES delay is built on the DD2. You could incorporate the switch in a similar way - probably switching between long and middle would be equivalent to the Cornish Tx4 switch.

[philrob1]

Welcome to the forum!

From the schematic you posted, it looks like the delay time pot controls a NAND gate VCO, which is fed directly into the microcontroller's clock input. The SML switch is input separately to the chip, and likely is used for some sort of clock divider.

The microcontroller RDD63H101 could potentially take different speeds, so an external clock with a wider range might work. The schematic says the clock range is 1.28MHz-5.18Mhz. This probably not the best idea.

You might be able to adjust the clock low and high trims and hardwire the switch to the middle position to see if that gives a usable range for you.

http://www.synfo.nl/servicemanuals/Boss/DD-2_DD-3_SERVICE_NOTES.pdf

One feature that should definitely be possible for the DD-2 is adding a switchable capacitor to the feedback loop to tame the highs.

Also, consider building a PT2399 delay like the Hamlet or Deep Blue delay. You might be able to find one smaller than a DD2 board that would fit better in a multipedal.

The Pete Cornish TES delay is built on the DD2. You could incorporate the switch in a similar way - probably switching between long and middle would be equivalent to the Cornish Tx4 switch.

Hi! Thanks for getting back to me and sorry for the delay in replying to your message.

I was taking inspiration from the Cornish TES (wonderful unit, used to own) - and I realised soon after I posted this question I was overcomplicating things.

I had one of the early TES pedals with the Boss DD-2 controls on the top, and I have played the newer version also. The "X4" switch is infact a DPDT switch that toggles between the Long and Medium settings - and Pete modifies the clock time to account for the longer settings. So therefore, I was complicating matters but thank you for your reply.

One thing you may be able to help me with - and I am asking from the POV of the DD-3 also - schematic below - how could I hardwire the FX so it is always "on" - I have successfully removed the dry signal, and adjusted some values to make it more "Tape Echo" - I just need to figure out the bypass thing.

I used to own a Cornish FX Board that had a DD-3 in it (Can be seen on Pete's website) - so I know it's definitely possible to do! Just without that Flip-Flop, I'm a bit stumped.

Thanks!!

http://www.synfo.nl/servicemanuals/Boss/DD-3A_SERVICE_NOTES.pdf

[philrob1]

--- spam linker's post removed ----

That is a 2P4T rotary switch

Think it's this one - https://uk.rs-online.com/web/p/rotary-switches/1239601/

[r080]

One thing you may be able to help me with - and I am asking from the POV of the DD-3 also - schematic below - how could I hardwire the FX so it is always "on" - I have successfully removed the dry signal, and adjusted some values to make it more "Tape Echo" - I just need to figure out the bypass thing.

It looks like the DD3 bypass is handled mostly by the microcontroller. When you power it on, is the effect on or off? If it is off at power on, then you probably need something that can give a single logic input to the switch input (probably would have to bypass the pull up on the switch). I think a power on reset circuit is what you would need.
http://www.sigcon.com/Pubs/edn/por.htm

Are you trying to handle all the dry signal and bypass without using the Boss buffers etc.? If the effect turns on when it powers up, then you shouldn't need to do anything, really.

[philrob1]

One thing you may be able to help me with - and I am asking from the POV of the DD-3 also - schematic below - how could I hardwire the FX so it is always "on" - I have successfully removed the dry signal, and adjusted some values to make it more "Tape Echo" - I just need to figure out the bypass thing.

It looks like the DD3 bypass is handled mostly by the microcontroller. When you power it on, is the effect on or off? If it is off at power on, then you probably need something that can give a single logic input to the switch input (probably would have to bypass the pull up on the switch). I think a power on reset circuit is what you would need.
http://www.sigcon.com/Pubs/edn/por.htm

Are you trying to handle all the dry signal and bypass without using the Boss buffers etc.? If the effect turns on when it powers up, then you shouldn't need to do anything, really.

Hi, thanks for your reply.

I was overcomplicating things (again)...!

I have been successful - bearing in mind for my purposes, I don't need the LED "On", I just need the wet signal audible as I will be placing the DD-2/3 circuit within a parallel mixer.

I have removed Q010 and bridged across the Pins, omitting the Diode D008. I have also removed Q002 and R043, which has muted the dry signal - though I probably only needed to do one or the other.

For reference, on the "Startup" state, the FX is "Off"

[potul]

Is there something I can buy to add to my pedal board that can make it so I can turn two pedals on simultaneously? Like step on one switch and have my boost and delay come on at the same time?

You can use some kind of loop pedal. There are programable ones that will allow you for presets and multiple loops, or if you only need these 2 pedals to go in sync, you can use something like this:


https://es.aliexpress.com/item/4000189818521.html

It is basically a loop with a bypass. If you put both pedals in the loop, and leave them on, you will be able to bypass them with one button.