percussion question

[Ted Kendrick]

For all you experts. Is the percussion switch assembly phsically different on b3/c3 organs than on m3s? I wanted to cut out an opening in the drawbar trim panel of the c2g and install a m3 switch assembly, but room is too tight. Just wondering if there were two different assemblies.

[David Anderson]

The switch boxes are the same. You need to take a closer look at the different Hammond models. When Hammond came out with the C3, they had to relocate the Start/Run switches into the music rack woodwork to make room for the percussion switches.

So, no, trying to install 3-series switches in a 2-series organ is kind of a no-go since the metal drawbar base is already punched-out for the Start/Run switches. I guess there's some way to patch it all in if you don't mind it looking amateurish, assuming you're not someone with access to a laser CNC machine or something like that. Doing it by hand will make a mess. And then you've got to relocate the Start/Run switches.

This is why Trek II's percussion controls replace one of the cheekblocks.

[enor]

The only difference between the switch assemblies is the length of the cables. The main problem, like David says, is that the -2 series drawbar base already has holes in the wrong places.

[muckelroy]

Physical layout issues aside, there's also a toggle switch mounted underneath the B natural preset key on the upper manua.
EDIT: I originally posted that this switch toggles between the percussion keying busbar (1') being sent to the percussion circuit, or not, but now I think that this switch is actually used for percussion volume.

Interestingly, the current version of the Trek II percussion unit lacks an on/off toggle switch, meaning when you use the upper B natural preset, the harmonic wired up for percussion keying is always muted, even if percussion faders are at zero. This is a well known limitation and easy to get around by adding a toggle switch if you so choose, at the expense of having to throw a separate toggle switch to enable percussion later. So, if you transplant a percussion switch assembly and AO-28 preamp properly, you should have the percussion on/off properly enable / disable the 1' keying busbar.

[Sweet Pete]

This 1999 TP2-B is the current version.

[Drawbar Dave]

Physical layout issues aside, there's also a toggle switch mounted underneath the B natural preset key on the upper manua.
EDIT: I originally posted that this switch toggles between the percussion keying busbar (1') being sent to the percussion circuit, or not, but now I think that this switch is actually used for percussion volume.

Interestingly, the current version of the Trek II percussion unit lacks an on/off toggle switch, meaning when you use the upper B natural preset, the harmonic wired up for percussion keying is always muted, even if percussion faders are at zero. This is a well known limitation and easy to get around by adding a toggle switch if you so choose, at the expense of having to throw a separate toggle switch to enable percussion later. So, if you transplant a percussion switch assembly and AO-28 preamp properly, you should have the percussion on/off properly enable / disable the 1' keying busbar.

When the B natural is up, the switch grounds the wire. When it is depressed the ground connection is broken. It's a non latching momentary type switch.

[Sweet Pete]

When engaged below upper B preset supplies the R1 volume drop of drawbar/perc 'ratio'. I 'short out' R1 on mine so it is not needed.
When volume 'normal' is used instead of 'soft' I prefer NO volume drop on my drawbars thanks.

[enor]

The switch under the B preset key only regulates a feature that most people dislike and many disconnect - the upper manual volume drop on percussion "normal". If you don't consider that function a must, then no need to bother with that switch.

[muckelroy]

M3 doesn't need the extra 'switch under the B preset' because it has no presets. Main signal is dropped in volume via R1 inside the matching transformer when percussion is turned on. You can bypass R1 if you want, just like on consoles.

[enor]

RLangham: Out of all the spinets, only the M-3 has this function.

[RLangham]

Is there a tutorial for that on here? I know a lot of common spinet mods have a ton of information on the forum...

[Sweet Pete]

Easier to locate/purchase a correct -3 drawbar base than butcher a -2 base.
Someone on the Hammond Tech FB group was 'punching' these out CNC and had them for sale to make use of 'M3' switches.
A lot easier to rework the wood music rack for run/start switches.
Would still have to punch out the hole for the switch pictured, below upper manual B preset.
Don't really need the switch though,will work without the 'volume drop' (R1 bypass) just fine.
This B2 has the TrekII TP-2B cheekblock mounted percussion unit.Trouble free operation since 1999.
At first I didn't like the 'faders' type controls,grew to really like them.The 'plunk' is actually woodier than a stock AO28 circuit to my ears.
Easiest path is the Trek,if you insist on 'stock ergonomics' that look correct,get the -3 base and the switch,be prepared to 'plumb' the switch and music rack.