Sure you could do something like that, but I don't recommend it. The MX61 is a stereo instrument, many of the sounds are sampled in stereo, and certainly, the on board effects are stereo. So you will not be able to sound properly and the effects will make isolating the bass difficult (if not impossible) Certainly others who own an MX will wonder ... What's wrong with your MX.

The Rotary Speaker, for example (which we already know you'll be using), is a very stereo effect. Very stereo! In order to achieve the proper Doppler Effect of rotation it requires two speakers. We hear from many (too many) Yamaha synth owners who don't think the Rotary Soeaker effect is that good - then we talk with them and discover that they've been listening to it in mono. Well, it's not quite the same. Mono is one thing, if all you hear is the mono signal, you have no idea what a difference stereo makes.

Stereo is like trying to describe to some one who has never tried it, how good ice cream is going to taste _ they might be thinking it looks similar to mashed potatoes so it probably taste like that 🙂

That said, there is no harm in trying. Unfortunately at the MX price point, there is no separate assignable output. This makes your idea about a separate bass amp not feasible. You can definitely MIDI IN from the pedals and set it a Part on its own MIDI Channel. You have not told us enough about your setup for us to make useful suggestions... But here's what I suggest:

If, as mentioned, you have no separate assignable output on the MX, separating the bass can be done with a sound system that includes a sub woofer for your bass... Instead of a bass amp.

Example setup: Yamaha StagePas 400i or 600i + a SubWoofer.

Lightweight powerful. (The 400i is 200 Watts per channel_ 125dB SPL, the 600i is 340 Watts per channel_ 129dB SPL) it has Stereo channels for your keyboards and when you plug in a powered SubWoofer to its dedicated Sub Output, it automatically does the crossover thing and divides signal below 120Hz to the Sub. Nifty, neat, and the sound you will not have to apologize about at all! The whole StagePas is so nifty, it packs up like musicians designed it. You'll love its portability. And the sound will blow you away.

That is how I would recommend you divide the bass separately _ to a subWoofer. It will allow you maintain your keyboard's optimum stereo sound, give you plenty (and IMHO), much better bottom on your bass. And instead of other MX owners wondering why your keyboard sounds some how diminished, they'll be asking you about how you pulled off such high fidelity quality on your keyboards and such definition on the Bass, without compromise.

Learn all about it here: http://usa.yamaha.com/products/live_sound/pa_systems/

Just my thoughts. 🙂

And all excellent thoughts, Bad Mister, thanks -- some of which have been shared by my sound buddies (subwoofer, in particular). As I say, the split to bass amp is not a must-have, but based on your suggestions, I'll definitely plan to run the MX stereo (I use an EMX 212S). I got questions about how to MIDI in the pedals, but another day -- I'll still trying to figure out how to control that rotary with my big toe 😉

Okay, got my MX61 and playing in stereo -- very nice indeed. Got my PK5A pedals MIDI'd in and, since bass is on Part-4 in the performance I'm experimenting with, I set the pedals to send on channel 4, so now I'm able to pick the bass voice I want and all that's cool. My question is how do I assign the Assign-1 knob to control the PK5A volume. I tried some things (per Ref Manual and Data Liist) and it seemed to work, but then after I exited the edit process, Assign-1 didn't seem to have any effect on the bass volume... Kinda got lost in that whole process. Anyway, is there be a way to globally set Assign-1 to control the volume of Part-4 (or a specific MIDI channel)? Seems to me that would be simpler.

Okay, got my MX61 and playing in stereo -- very nice indeed. Got my PK5A pedals MIDI'd in and, since bass is on Part-4 in the performance I'm experimenting with, I set the pedals to send on channel 4, so now I'm able to pick the bass voice I want and all that's cool.

Awesome, seems you are settling in nicely with your MX61.

My question is how do I assign the Assign-1 knob to control the PK5A volume. I tried some things (per Ref Manual and Data Liist) and it seemed to work, but then after I exited the edit process, Assign-1 didn't seem to have any effect on the bass volume... Kinda got lost in that whole process. Anyway, is there be a way to globally set Assign-1 to control the volume of Part-4 (or a specific MIDI channel)? Seems to me that would be simpler.

if I understand your setup, the PK5A is being used to control the MX61's Part 4. The PK5A is sending Midi messages on Channel 4, triggering the sound of the MX61. So when you say you want to assign a Knob to control the PK5A volume, there is no volume to control - the PK5A has no tone generator. I think you mean to say you want a Knob to control Part 4's Volume, correct. The volume of the Part the pedals are controlling.

The device acting as Master (in this case your pedal board) should be used to send the volume setting that you want to your receiving tone generator (in this case Part 4 of the MX61). According to the PK5A manual: pedals 4-B can send specific Volume (cc007) values on whichever channel you desire.

As you discovered, the MX works like this... It transmits on only one MIDI Channel at a time, you select the Part 1-16 and you are transmitting to that Part. (In order to play multiple MX PARTs you place them on the one Midi channel).

If you *select* Part 4, the MX as a controller will *play* Part 4, the sustain pedal will sustain Part 4, the MW will modulate Part 4, the PB will bend Part 4, the Assignaable Knobs will affect Part 4, the keys will trigger Part 4... Etc.

You cannot be physically playing on MIDI Channel 1 while the Assign 1 knob is controlling what's on Midi channel 4, sorry.
(That would be in the next model up the Yamaha Music Production ladder of products, the MOXF and Motif XF can certainly do this because you can simultaneously transmit on multiple channels with those products).

It makes sense to control the Volume from your pedal board. If you need a quicker adjustment, say via the Assign 1 knob, you will have to select Part 4 to have the Assign 1 knob affect Part 4.
Press [PART SELECT]
Press [4]
The controllers will now address the Voice in Part 4.

Hope that helps.

Thanks, Bad Mister, and yes, you have the picture exactly. And I really appreciate you digging into the PK5A manual for me. I may need to get on a Roland forum to get a better handle on how and where to send the cc007 value and what it does. (I did seriously consider the MOXF after watching one of your video demos, but just couldn't justify it as it's not my main instrument.) A little disappointing on the Assign-1 knob, but explains the results I was getting. Will experiment a bit more on how best to handle the bass volume in a live situation. May ultimately opt to stick with the PK5A into the Alesis QSR...
Thanks again, and stay tuned 😉