Hammond M3 foldback kits. Any advice?

[melish]

I'm thinking of adding foldback to the upper manual of my M3. Has anyone had experience with this? Can anyone recommend a particular kit? </p>

Any helpful thoughts, advice, or opinions on this topic are appreciated.</p>

Thanks!</p>

[Brendon Wright]

Re: Hammond M3 foldback kits. Any advice?



The M3 kits cost a bit more 'cos they include a full length bussbar to replace the half sized one.</p>

Two places that sell 'em (that I know of) arehttp://bullfrogmusic.ca/keys/foldbac...spinet-organs/</p>

and this place in the UK reports to be able to provide 'em as well.</p>

You'll want to do manual tapering at the same time too, involves a bit of wire and some resistors.</p>

This guy did it on his M:http://www.sympac.com.au/~retrojet/foldback.htm</p>

I've got plenty of photos and advice from when I did my T500.</p>

I've gotta zoom right now though....</p>

-Brendoon</p>

[dzlvs8]

Re: Hammond M3 foldback kits. Any advice?



Ok.  I'm on to my next fix for my M3.  The manual tapering.  Since I am powering my Leslie 147 (that doesnt have an amp in it) with my 25watt amp inside my M3 I often play at full volume therefore I cant boost the highest notes with the swell pedal.  This makes my high notes sound too "nice".  I want them to scream!  That sympac site has been down for quite a while but i think I have seen some pics of someone doing this somewhere.  Probably your pics, Brendon. lol   But I need to be pointed in the right direction in order to be able to do this mod.  Do you have some instructions or are there some somewhere else on the web.  I have looked but cant find them anywhere.</P>


</P>

Also, I have seen your chart of the tapering scheme you got from somewhere.</P>

http://keyboardpartner.de/hammond/diagrams/KeyboardTapering.png</P>

FYI - that thing makes no sense to me because i dont know what the multicolor code is for.  It says "spinet lower/upper manual range"  I dont know what that is supposed to mean. CLARIFICATION:  I understand what that means but I dont understand why it says after that (no tapering!).  Does that mean that there is no tapering on an M3?   But anyway, I am not sure if understanding that chart completely matters since I am trying to mod my organ so it doesnt have that manual tapering scheme.</P>


</P>

Can you direct me to some instructions for this mod?  Also, is this one of those, tear the entire organ apart type of mods that is going to take a week.  Because I am not about to tear my entire upper manual out of my M3.  No way!</P>

[redoctoberff]

Re: Hammond M3 foldback kits. Any advice?



The mod requires adding 36 resistors-one to each key in the upper octave for the first three drawbars-to the resistance wires inside the manual, so yes, you will have to take apart the upper manual. From what I understand it's fairly similar to foldback in terms of the work involved.</p>

In order to understand the mod you need to understand the way that tapering works. The Model A (and I think the E, although I'm not sure of that) and all spinet organs have *no* tapering in the manuals. In other words, no work was done to balance the respective volumes or "natural" volume taper of the keys--all have 16 ohm resistance wires. The later consoles have resistance wires that are less than 16 ohms to increase the volume of the notes in the top octave, for the first three drawbars only.</p>

The mod involves soldering a 27 ohm resistor in parallel with the existing resistance wire for each of those 36 notes. I had the relevant info at one point but can't find it right now. Brendon should be along shortly and can help you out--as far as I know he's the only one who's done it; sounds like it was an idea of Kon's that he never get around to messing with. I might do it to my M this summer, if I can also secure the parts to do foldback.
</p>

[dzlvs8]

Re: Hammond M3 foldback kits. Any advice?

Yeah, ok I have seen pictures of this mod being done, I think. But I saw the resistors added to the wires and then connected to the key contacts. If thats all I need to do, I can open up the back of the manual but I dont have to actually take the manual out. This sounds like as much work as adding poor mans foldback. The real version of fold back sounds horrible. If this job is anything like that I dont want to do it.


Here is a link to my video on adding poor mans foldback.  </P>

http://www.youtube.com/watch?v=rfSn0BtSYzI</P>

This shows how easy it is to access the key contacts on the M3.  I wouldnt even have to raise the manual for this mod.  Thats the worst part about adding poor mans foldback.</P>


</P>

Since you said that I need to add 36 resistors, I understand the chart that Brendon posted now.  I cant wait to do this.  I just need some confirmation that I just need to take the wires off the key contacts and then solder the resistor from the key contact to the wires.  Then I am pretty much good to go, except I am not sure which key contacts  are the 16 ones and which ones are the 8's or the 5 1/3.  I know that they dont go in order from top to bottom on the manual but thats all I know.  Anyway,  I cant wait to do this.  The best to mods I have found have been the easiest and they both partially came from Brendon.</P>

[Harold]

Re: Hammond M3 foldback kits. Any advice?

I've done two foldbacks,, it's a lot of work and one mistake means taking the wholle manual back apart to fix the problem,, it's just a ton of work,, one of my biggest problems is just not scratching everything up,, so if guy had a prstene organ and he wanted foldback ,, I would be nervous,, I got M2s for my parts,, you can find them really cheap,, most people don't know much about foldback so it's hard to get people intrested,,

[redoctoberff]

Re: Hammond M3 foldback kits. Any advice?

I don't think the resistors are connected directly to the contacts because then they could not be wired in parallel with the existing wires, they would be wired in series. You may be confused with the other set of resistors Brendon had inside his manuals for another mod which may have been connected that way. You have to wire in parallel so that the resistance *decreases* otherwise you would have added resistance from the 27 ohm resistors.

[Brendon Wright]

Re: Hammond M3 foldback kits. Any advice?



Agh,</p>

I'm here now, but my brain is still swimming in the dregs of the last cup of coffee and looking for more. I hope it catches up with me soon....</p>

The resistors attached to wires, as seen in the below pic are either when I've run out of contacts for foldback (and cut spare contacts from the drum machine percussion on my T500's lower manual) or when I was doing the tapering... but in both situations I was using fresh (enamelled) wire, not special resistance wire (hense the added resistors): </p>

</p>

That little reel gives me something like 50 metres of wire!!!!! I'm NEVER going to use all that up...</p>

So, just to give you the definitive on it, you leave the existing resistance wires AS is.</p>

However, I hear that an M3 is DASHED awkward to get inside the manuals on, because the spinet's cabinet top is glued in place, leaving very little room for manouvering. Geoff Williamson found he had to stand the manual up vertically to work inside it!</p>

Please take notes (and photos?) if you do it, I need a first hand text from someone doing the job inside an M3... so the manual can be written up for general spinet foldback and tapering. </p>

</p>

Here's a recording from a cupla nights ago, the 16', 5 1/3' 8' and 4' are fully out on both manuals. The top octave has tapering, so is louder than the rest, quite nifty... and the lower is dropped an octave. Great for smears and left hand bass.</p>

Since then I've mucked up my pedals and swell, there's always work for the DIY modder....</p>

http://cid-0d7741cc63af1adc.skydrive...20and%20Dm.MP3</p>

The recording was a low quality mono from a digital camera. Converting from Wav to MP3 dropped it from 44bps to 40bps, I don't know how that will affect it on your computer....</p>

Cheers!</p>

-Brendooon</p>

[dzlvs8]

Re: Hammond M3 foldback kits. Any advice?



Hmmmm.....Me still a little confused. But first off,  your audio track sounds awesome.  I am DEFINITELY going to do the manual tapering as soon as the electronics store opens back up on Monday. </P>

I think I will have enough room to get into my manuals.  Here is a pic of my upper manual with the back cover off on the manual.  It is tough to get back to the terminals without being able to take the top cover off of the organ but will and determination have allowed me to get in there and do the soldering before. The gray boxes are just covering up some wording from when I wrote up instructions on adding foldback.</P>

</P>

If I understand everything correctly now I need to add a new wire from the correct terminal number (terminal 1 being the furthest most terminal to the right when looking at the back of the organ) to the correct key contact.  Therefore there will be two wires conected to each key contact that I have added a resistor to.  I have scribbled a very basic pic of this up.  </P>

</P>

I wont say that this mod is at all easy, but it is definitely doable.  The parts that I am still confused on is:</P>

1. Understanding which key contacts belong to which drawbar.</P>

2. Your wire is not insulated so I would assume that it is making contact with other uninsulated wires that you have added?  I thing I am just going to try to cram 22 gauge wire in here, because I do not understand how you were able to wire the thin wire that you have without the exposed wires touching each other.</P>


</P>

If you (Brendon) or someone else can direct me forward by answering these two questions, I think I will be able to tackle this project.  I will definitely take pics as I go.  Your high octaves sound awesome! Thanks</P>

[dzlvs8]

Re: Hammond M3 foldback kits. Any advice?

I deleted this post. It was no longer a question.

[dzlvs8]

Re: Hammond M3 foldback kits. Any advice?



Oh shoot!  Another problem, redoctober mentioned that I need to add in 36 27ohm resistors???  I dont show 27ohm resistors anywhere in the manual tapering chart.  From what I am reading I should be adding in 10ohm resistors to the following keys/keycontacts.  see pic.  (sorry for all the questions)</P>

</P>

[dzlvs8]

Re: Hammond M3 foldback kits. Any advice?



OOOOK.  I am determined to do this.  Here is what I have come up with.  Basically I am looking for confirmation on this and also verification that the 27ohm resistors are the way to go.</P>

I dug through the M3 service manual and found the key contact wirings.  So know I know what contacts are for what draw bars (without having to use a multi meter and what not.  I am posting the pic here in case anyone else needs the info. (and because it took me a long time and I dont want it to go to waste)</P>

</P>

Now that I know what key contacts I am connecting with a second wire and resistor to, I just need to confirm the size of the resistor and know which key contacts the wires are going to.  Please see pic in the post immediately above this one where I highlighted which key contacts need to be wired.  I think these are the correct key contacts to modify. Can anyone verify this and and the size resistor.  (NOTE: I plan to use very high gauge insulated wires.  I dont think I can manage not shorting out a bare wire against another one while doing this.)</P>


I've almost got my brain wrapped around this one!!!  AND my radio shack is going to open in 9 hours!  lol
</P>


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[stefanv]

Re: Hammond M3 foldback kits. Any advice?



If you're trying to achieve 10 Ohms by wiring a resistor in parallel with the existing 16 Ohm resistance wire, they you'll need a 27 Ohm resistor. The resistance of 27 Ohms paralleled with 16 Ohms is (27 x 16) / (27 + 16) = 10 Ohms. Another (equivalent) way to calculate this is 1 / (1/27 + 1/16) = 10.</p>

Note that the wire that Brendon showed is not bare wire. It is enamel coated. You can still short it out if it rubs against a sharp edge, which will scrape off the enamel, but it is insulated wire. Personally though, I'd use thin wire with plastic insulation. A great source of this stuff is old 25-pin straight-through serial cables, which contain 25 wires in 25 different colours. That would make it a lot easier to keep track of which wire is which. I've been using that in wiring up a keyboard in my current project: http://www.stefanv.com/electronics/p..._n_thingz.html (see the last two photos if you want to see a lot of wires).</p>

PS. Has anyone tried using this site with Google's "Chrome" browser? I find the site looks fine, but I can't respond to posts. Everything I write doesn't show up when I preview the post.
</p>

</p>

[dzlvs8]

Re: Hammond M3 foldback kits. Any advice?



Thanks for the info, stefan.
The calculations are helpful.  Since my previous email in this thread, I had confirmed that I did need the 27 ohm resistors, but I didnt understand the calculation.  Now I do!  In regards to the enameled wires, I originally hadn't noticed that Brendon stated that he was using enameled wire.  I understand how it works.  My first idea was to use some 24 gauge plastic coated wire but I am going to give it a go with the enameled wire because it is available in a 3 pack with three different colored wires which will be perfect for wiring to the buss bars for 3 different drawbars.</P>

I am all set now.  Now all I am doing is waiting for the metal film resistors to be shipped to me, because none of my local stores seem to think it is important to carry the metal film resistors.</P>

[dzlvs8]

Re: Hammond M3 foldback kits. Any advice?



I thought I should clarify that my picture of the drawbar "to" key contact wiring diagram above had the drawbars labeled backwards.  HERE is the information that I've come up with.  Although it may not seem important for some people to connect their wires to the correct key contact.  I would like to do so because of how the key contacts don't all connect at the same exact time.  HERE is the updated wiring diagram.</P>

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