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Some spinets (in particular, those with percussion, like the M3's) already have some of the key contacts which you need for AddingFoldbackToASpinet. (These contacts are required for triggering the Percussion.) In this case, one can add partial HarmonicFoldback (eg. only on the upper drawbar on the upper manual) without adding any extra parts.

(It's not completely clear why Hammond didn't do this in the first place.)


Adding Poor Man's Foldback to an M-3


Sep, 2013 UPDATE: I have put together a complete video of this process which should be much easier to follow. http://youtu.be/LRp95Wr3Rmg Best Wishes, Steve Blair


These instructions were posted to the HamTech mailing list (on 6 July, 1999) by SteveBlair.


Here's a detailed description I put together after doing this on my M3. Lots of thanks to Lars Mikael (CaptainFoldback) for this idea.

(Remember to prop the manual up as high as possible so you can work in this area.)
You'll see the large black generator wires attached to the front strip and the white wires attached to the back side of the same strip.
(See Detail Wiring Chart below, then return here.)

Again, I want to give full credit to Lars for this mod. I love it and don't know why hammond didn't make it a stardard feature.

Enjoy! --SteveBlair


Detail Wiring Chart

Here is the complete connection listing. I will start from the highest C and work down.

Key Frequency Lug ----- --------------- Highest C 85 <==7th lug from right side B 84 <==8th lug ... Bb 83 etc A 82 etc G# 81 etc G 80 <==12th lug from right side F# 91 <== first lug on right side F 90 <== 2nd lug from right side E 89 <==3rd lug ... D# 88 <==4th..... D 87 <==5th.... C# 86 <==6th.... 2nd Highest C 85 <==7th lug from right side B 84 etc Bb 83 etc A 82 etc G# 81 etc G 80 <==12th lug from right side

From this list, you can see that the frequencies "foldback" at the 2nd to highest G, then again at the highest G. Therefore, the wires for these two notes should be attached to Frequency # 80, which is the 12th lug from the left. That's what foldback means, the frequencies simply repeat because you've run out of new frequencies above # 91. So, with only the 1' drawbar pulled out, when you press any of the highest three G keys, you get the same tone, or frequency # 80.

Make sense?

Also from the chart, you can see that you only solder 1 new wire to the 6 rightmost lugs, and 2 new wires to the next 6 lugs.


TopicModification

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