Hi, I would like to modify the center frequency of my Bass MuRF so I can use it with a guitar or higher fundamental frequency instrument. There aren’t any schematics AFAICT on the 'net, however the ubiquity of the Moog ladder filter should help identify the changes for those with long experience 
I just got it yesterday and was hoping someone has been through this territory already.
Thanks!
John
I’m fairly certain that this has been discussed on the forum before - try searching for it.
From what I recall, no results in the way of success were reported. The MIDI MuRF does have this capability; that doesn’t mean that it can be done, but is a solution to satisfy your needs.
I thought if you have the LFO switch set to off, then the LFO/Sweep CV input would control the sweep of the filter. Is that wrong? I haven’t experimented with that yet. That may be a idea to try anyhow.
@alien8 - I’ll give the search another workout. I maybe either too restrictive on the keywords or using slightly different jargon.
@Bryan B - Hmm… I’ll have to give that a shot when I get a CP-251 or other CV source I can manually adjust. At the moment it’s hard to get fine control with CV’s from my current MF’s; 101, 103, 108M.
Just so I’m clear I’m looking for a way to shift the 105B filters up an octave into the guitar range similar to what the HI/LOW switch on the 105M does. FWIF, I have a 105m on the way so, the subject is probably moot. However, if there was a simple change I would definitely through a switch on the 105B to get the functionality.
I somehow missed that you had a Bass MuRF and not a Midi MuRF, sorry. I don’t remember what CV inputs that had. I would think a foot pedal might be the control you would want. You could create a Pot control using the pedal supply voltage. That would require soldering and a little DIY experience to make. I would try to describe it here if you wanted.
I wonder if they put a jumper or switch on the PCB for the Hi/Lo frequency? It would make sense if they made the Bass MuRF and regular MuRF on the same PCB layout and just had a switch or jumper between them.
Try contacting Moog directly - may a phone call. They are pretty good about answering questions like this.
We have discovered the possibility of the 101 trigger mod, midi Murf stereo out mod and the 104 spillover mod this way.
Thanks for the insights folks. I have all three pedals now - eventually I may open them up for a look see. Until then, just enjoying them
Please post a comparison once you get to know them! And pics if you find differences.
Enjoy! Fun pedals!
I certainly shall! One thing I immediately noticed was that all of the perceived disadvantages of the 105B was that I was limited myself to a harmonically poor clean guitar instead of something like the Sub Phatty which knocked my socks off! I have to try all three 105’s in parallel with slightly different rates
I too have all three flavours of Murf. I’ve been using them at different points in my FX chain, before a 104 Delay, or after it, or both. When running all three, I find it best to be gentle on the Mix percentage, so that all three can influence the overall mix without overpowering anything. Mostly running my modular through it.
Stephen
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Great tip Stephen!