B/C/M solid state percussion circuit (much like the Trek II product)

[Guest]

Hello again, </p>

I am starting to think its time for percussion on my Hammond DV. I was hoping somebody out there has the circuit diagram for a small transistor percussion I could build instead of spending $$$ on a trek II percussion unit. The circuitry for percussion should be very simple and I would much rather spend $20 on parts than $200 on a trek II perc. </p>

If all else fails, I can either design my own or reverse engineer the old SS percussion mod in my M2. I'd like to hear your thoughts.</p>

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Cheers
</p>

[jimmywilliams]

Re: B/C/M solid state percussion circuit (much like the Trek II product)



Hi. I can't help with the circuit design but ... I may be picking up an M2 soon. What is this old solid state percussion circuit you are talking about in yourM2? Who made it, and is there no schematic available? I was thinking the only way to get percussion on an M2 would be to get an M3 amp and the percussion switches and wire harness - but that is not very cost effective either. I was looking into the TrekII but if I am understanding it correctly there is no way to turn the percussion off and regain whatever drawbar the percussion unit is wired into... and I think it costs more than an entire M3 organ would sell for. I am new to Hammonds anyway so I figured the percussion can wait while I learn the ins and outs of playing it.</P>


I'd be interested in whatever you find out about rolling your own percussion circuit.</P>


-jim</P>

[Guest]

Re: B/C/M solid state percussion circuit (much like the Trek II product)



When I bought my M2 it had some sort of homemade percussion unit in it; Its kinda funny, it was wrapped in tin foil as shielding. Anyway - I hardly use it because its a bit noisy when its turned on - but its a pretty simple circuit and I can probably modernize the design.</p>

</p>

The Trek II can be turned on and off... the drawbar signal is routed though the circuity and a small amplifier follows a percussive envelope when a key (any signal) is detected. The Trek II has the same 4 tablets as a B3/C3/M3 and the same functionality and sound.
</p>

I would have thought someone would have this circuit lying around, it seems like a great project for any early series console owner..
</p>

[geoelectro]

Re: B/C/M solid state percussion circuit (much like the Trek II product)

[quote user="soundengg"]

The Trek II can be turned on and off... the drawbar signal is routed though the circuity and a small amplifier follows a percussive envelope when a key (any signal) is detected. The Trek II has the same 4 tablets as a B3/C3/M3 and the same functionality and sound.
</p>

I would have thought someone would have this circuit lying around, it seems like a great project for any early series console owner..
</p>

[/quote]</p>

The Trek II Percussion Kit cannot be "turned off" as it uses three slide pots for the three pitches that can be percussed. A fourth slider controls the decay. You turn off the effect by turning the pot volumes down. It's always on.</p>

This is likely because the three tonebar pitches it borrows are sent back to the drawbars so they still work. The original percussion worked the same way. A fourth drawbar is used for keying. I don't believe it is practical to try to trigger an envelope with the very small signal at the drawbars and provide the mono keying that is customary. The B-3 worked the same way borrowing the 1' drawbar for keying so that drawbar didn't play with percussion on.</p>

The Trek II kit borrows the 1 1/3 drawbar for keying and it does not come back. That drawbar is sacrificed for the percussion effect.</p>

The Trek II percussion head that had 4 rocker switches came with the SSP-3 Preamp.</p>

Geo
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[Guest]

Re: B/C/M solid state percussion circuit (much like the Trek II product)



Thanks for the clarification Geo, its great to hear from someone who has first hand experience with the unit.
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I am a little disappointed that there is no '4 rocker' trek II percussion unit; I really just want the functionality of a '3' series organ - oh well, more features is never a bad thing.
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So if the Trek II borrows a drawbar to trigger the percussion would I need to add an extra wire to all of the 1 1/3 key contacts to provide the triggering signal? (and a wire just before the drawbars do that the signal is not attenuated?) That seems like a lot more wiring than I expected to install the trek II perc.
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[geoelectro]

Re: B/C/M solid state percussion circuit (much like the Trek II product)



No sir, you just use the drawbar wire which IS connected to all the existing contacts. </p>

BTW I believe the rocker control head is even currently unavailable due to scarce supply of switches.</p>

Geo
</p>

[Guest]

Re: B/C/M solid state percussion circuit (much like the Trek II product)



I just had another thought, I looked at the AO-28 schematic and the
percussion circuit is VERY simple but I would need to get a B3's
matching transformers. Correct me if I am wrong, but it seems like the
L-100's percussion unit (already in a separate box) does not require a
special matching transformer and I could use the B+ and heater power
from the other amp. </p>
AND!! there is a L-100 on kijiji for $80

[Brendon Wright]

Re: B/C/M solid state percussion circuit (much like the Trek II product)

Aar, there be a member here who's parting out a T100 which has a percussion board..... I wonder if that would transplant?

[Guest]

Re: B/C/M solid state percussion circuit (much like the Trek II product)



Hi, I am David and I am a Hammond-a-hollic...</p>

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I just bought a hammond L-102 to chop and steal the percussion from....
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[johnny b3]

Re: B/C/M solid state percussion circuit (much like the Trek II product)



ahhhhh.....</p>

the L-100 perc is okay, but it's no -3 series. Copy the ao-28 perc circuit, it would be way more fun and sound more authentic.
</p>

I just added percussion to my BC using the rocker switches from a dead M3 and installed an AO-28 preamp. You don't need a B3 matching transformer for the job! The only reason the percussion interfaces with the transformer is for attenuating the upper manual volume when perc. volume is set to 'Normal', and I'm told the feature is commonly disabled.
</p>

[Brendon Wright]

Re: B/C/M solid state percussion circuit (much like the Trek II product)



Well, it all depends...</p>

there's a certain stridency in the L percussion, just about any prog recording seems to have it cutting through there in the mix!</p>

I quite like it, actually. </p>

There's classic and there's classic... if you like prog, that L perc is a different kind of classic. </p>

Sure, blues, jazz, funk and motown are one thing, but rock and prog are classics too...</p>

I think (or rather know definitively) I like those various 70's Germanic and English Rockers better than Jimmy Smith....</p>

[redoctoberff]

Re: B/C/M solid state percussion circuit (much like the Trek II product)

If you ever do reverse-engineer that M2 circuit, you should post the schematic online. That'd be cool to see.

[jimmywilliams]

Re: B/C/M solid state percussion circuit (much like the Trek II product)

About the Trek II - I sent Tonewheel General a message asking if it can be used for the M2. THe Trek II productusage chart does not list it as being used with the M series organs http://www.trekii.com/Product_Chart.pdfso I just wanted to double check. I'll let you know what they say.

[jimmywilliams]

Re: B/C/M solid state percussion circuit (much like the Trek II product)

[quote user="jimmywilliams"]About the Trek II - I sent Tonewheel General a message asking if it can be used for the M2. THe Trek II product usage chart does not list it as being used with the M series organs http://www.trekii.com/Product_Chart.pdf so I just wanted to double check. I'll let you know what they say.[/quote] Rick at Tonewheel General says it will work with the M2 ... but it was designed to fit into the endblock of the console models - so you would have to figure out some way to mount the unit in the spinet organs. If anyone is a member of the HammondZone yahoo group ... in the "files" section there are also several designs/schematics for tube-based persussion add-on units as well. - jimmy

[jhelm_waterw]

Here is my big question. Why does the percussion circuit need to disable/steal one of the bussbars/tones for a trigger circuit? Has not anyone tried to just use a "detector circuit" (much like the one found in an audio gate) tapped to one of the tones as a trigger? The only reason I can think of may be a very very slight detector delay (which is frequency dependent). The higher the frequency used for the detector, the less the "time lag". But I figure... tapping the signal at drawbar 9 and hitting the Lowest key (C), the detector would "see" harmonic 49 from the tone generator. So whatever freq that is, is the lowest freq we'd ever see. I could design a pretty damn fast and sensitive trigger detector for that using only op-amps and a few diodes/resistors/caps. I am an E.E. and I have designed 100's of audio circuits from scratch. Any thoughts on this approach?