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Thread: Conn Nylon Contact Technology

  1. #1
    ppp Pianississmo JoelHof's Avatar
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    Conn Nylon Contact Technology

    A curious question ... Is anybody familiar with the technology behind the use of the nylon rods in the Conn organ key contact setup? I read somewhere that the purpose behind what they did was to control the attack of the signal. Apparently if one replaced these nylon rods with something conductive such as a piece of model railroad track as someone did, the signal would be instantaneous and not sound right. Does anyone know how it works with these rods? Is it resistance in the rod? Capacitance? Is the nylon impregnated with graphite or some such conductor, or is there just some sort of coating on a nylon rod? How do they actually work? Would someone be able to replace these rods with a normal conductor and add a simple fixed/adj. ADSR circuit to that particular bus/sound/signal to get the desired envelope. Is it even possible with the way the keying is setup voltage wise and how it interacts with the actual sound generation circuit? It would help if I had the schematics in front of me so I could at least answer that last question on my own but alas ... none to be had at present. Last but not least, am I way out in left field and shouldn't even bother?

    Reason you ask? I spent a good 8 hours today just on one octave of the upper manual of my 721, and I'm less than satisfied with the results. Granted, it wasn't a true working 8 hours but still, I can't seem to get the sounds consistent across all the voices from note to note. I've broken down which rod dictates which sound and it seems when I get one sound pretty good, not perfect, and start working on another, when I go back to the first, it's not right again. I'm thinking variations in the nylon rod resistance, or whatever makes the rods function, and variation on where the contact wire hits? I just don't think I can clean this and get it back to at least close to what it originally was.

    There are ten rods. The back/top 6 rods are the white ones that rotate and they have no problems. They are all the main flute sounds, and they work even with dirty/black contact wires and not cleaning the rods. The white rods have a black strip of the nylon? running in a groove down them that rotates to make the connection. The front/bottom 4 rods are the fixed yellow rods with the black nylon? running in a groove down them, and they are the ones that won't make consistent contact after cleaning. These are the reeds, strings, diapasons, mod flutes. Are there two differing methods of sound generation being utilized here?

    Before I did anything the yellow ones made no sound at all. I used some light 180 one-sided emery cloth to clean the contact wires, and isopropyl alcohol on thin cardboard to clean the nylon side. I also tried CRC quick dry contact cleaner as someone else had good results on a different thread, but found the alcohol seemed to work a little better. Most of them came up pretty good, but inconsistent. Even gently sliding the contact wire back and forth to see if I could find a sweet spot didn't work well. Am I not cleaning them well enough. Over cleaning? I was pretty light when cleaning on the nylon side as I didn't want to rub anything off if it was indeed a surface coating. I only used the pressure of the contact wire between them with the key pressed down. But I do believe they are as clean as could be. I was able to rotate the first rod so I had access to the nylon in the groove and I cleaned that one with a q-tip and alcohol really well without being abrasive. Still inconsistent. Should I break out some acetone and try that? That may melt the nylon. Is it actually nylon or vinyl, or something else?

    The white ones/main flutes work like a charm. Gotta be a different type of circuit.

    Sorry for the long post but either way, gotta do something here. This ain't a workin' ... not to my expectations anyway.

    Thanks for any input,

    Joel
    Last edited by JoelHof; 06-14-2018 at 10:23 AM.
    Instr: Conn Artist 721 Deluxe, Kawai SR7A, Roland AT-80, Wersi Arcus
    Midi Ctlrs: Arturia KeyLab 49 x 2
    Sftwr: Arturia V Collection 4/5, ZynAddSubFX, Hauptwerk free ed, var. VST's, Ableton Live Lt, Ardour, Reaper
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    Need: Behr. FCB1010 Midi Foot Ctlr, Midi Ctlr (Akai APC40 mkII?), Small 8-12 chan. mixer (Mackie ProFX12v2?)
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  2. #2
    Moderator andyg's Avatar
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    1 members found this post helpful.
    This has been discussed many times over the years, Joel. The vinyl keying rods have become a pretty much constant problem with various ideas and attempts at solutions. I don't think anyone has come up with a real answer. Yes, people have replaced the rods with gold ones, the results being as you described, instant speech and keyclick.

    The idea of something like metal rods coupled with an envelope shaping circuit has been in my mind for some time, but 1) I don't have a Conn and 2) I don't have the knowledge to create something like that.

    As well as the surface of the vinyl rods being an issue, I'm sure that in some of the threads, our resident experts (including a couple sadly now passed away) have said that there's another problem with the vinyl coming away from the centre conductor.

    The forum's own search engine can be a bit 'iffy', but a google search often gets good results, try this, exactly as typed keying rods site:www.organforum.com

    And if you look at at the bottom of this thread you'll see a 'Similar Threads' box. A quick look right now shows "Gold plated rods for Conn 651" and "Conn 650 contact cleaning" for example.

    Have a trawl though and see if anything helps but always feel free to wake the subject up again. Who knows, that envelope shaping idea, if possible and do-able at a reasonable cost, could rejuvenate a lot of old, but very good sounding Conns.
    It's not what you play. It's not how you play. It's the fact that you're playing that counts.

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    Current organ: Roland Atelier AT900 Platinum Edition
    Retired Organs: Lots! Kawai SR6 x 2, Hammond T402, T500 x 2, X5. Conn Martinique and 652. Gulbransen 2102 Pacemaker. Kimball something-or-other.
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  3. #3
    ppp Pianississmo JoelHof's Avatar
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    Hello AndyG,

    I think I've read everything on the forum relating to the Conn keying but I'll run through it again for sure. Somewhere in my research over the past months I read how the different Conn's generate their sounds. How the 650 and 651 have the actual signal waveform running through the keying rods, and they changed that method on the 652/653 to a straight switching signal if I recall correctly. Maybe that's how the flutes work on the 721 and why there's no problem with them. I could be way off base on my understanding. Like I said, if I had the schematics in front of me I'd be able to tell by studying the design and the different keying circuitry. Working on that. My fear off the top of my head would be the necessity to have a different filter on each specific note as apposed to each individual voice. That's not gonna happen. Once I get my hands on a set of schematics I'll put the o-scope on the signals and see what's going on. I hate to just go in there now and poke and hope with limited knowledge and no map of what I'm pokin' at. I may do that just to see if the sound waveform is on the rod. If it's as simple, or not so simple, as an envelope circuit per voice, I'd be surprised that it hasn't been done before out of this illustrious crowd of organ enthusiasts. Then again, I could be way off base and don't understand this whole concept properly. I'll see if I can find where I read about the theory of operation on the 65x's. It wasn't too specific but at least a start.

    Joel
    Last edited by JoelHof; 06-14-2018 at 11:53 AM.
    Instr: Conn Artist 721 Deluxe, Kawai SR7A, Roland AT-80, Wersi Arcus
    Midi Ctlrs: Arturia KeyLab 49 x 2
    Sftwr: Arturia V Collection 4/5, ZynAddSubFX, Hauptwerk free ed, var. VST's, Ableton Live Lt, Ardour, Reaper
    Comp: Dell Prec. T5500-Win7/Linux Mint
    Need: Behr. FCB1010 Midi Foot Ctlr, Midi Ctlr (Akai APC40 mkII?), Small 8-12 chan. mixer (Mackie ProFX12v2?)
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  4. #4
    fff Fortississimo geoelectro's Avatar
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    1 members found this post helpful.
    The Tibias are not "audio keyed". They work well because the voltage and current is higher which can overcome any resistance caused but debris etc. They are either DC keyed or multiplexed keyed. The others are Audio Keyed (like a Hammond B3) and in order to reduce the key click inherent with audio keying, the vinyl bus bar is used. It is Elastomer if I remember correctly which is a carbon impregnated rubber type material. This was also used in Thomas, Baldwin, and Hammond Sounder to name a few. When the contact first connects the conduction is very low. The harder the contact presses, the more conduction and louder the note. This happens fast in real time which slows down the speaking attack of the note and eliminates key click.

    This was cheaper than building circuits to do this. It would require an independent keying circuit per note. If you tried it per stop, once a note was pressed the new presses would have click. Or, you could design it so every new key press would trigger the envelope but now every new press the already pressed note would "re-trigger".

    I have replaced these vinyl rods with gold rods and yes, there is key click but there is also way more reliable keying.

    Geo

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    fff Fortississimo tucsondave's Avatar
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    1 members found this post helpful.
    The contact wires are gold plated, at least they were before you used the 180 grit on them. The labels that are on the keyboards saying not to use contact cleaner were there for a reason.
    Since those organs were built Caig Labs developed Deoxit Fader F5 designed to restore conductive elastomer switches and faders. I have had good luck using it to restore the vinyl bus bars.

    td

  6. #6
    ppp Pianississmo JoelHof's Avatar
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    Thanks for all the great info!

    td: The contact wires that are in good shape are silver and not in the slightest color gold. Granted, the plating could have been extremely thin, but even on the thinnest of plating in electronics that I have experienced, even over long periods of time like decades, there was a definite gold coloring. Also, I've never seen gold plated components of any kind oxidize like these are. Completely black. Like tarnish? Some kind of silver plating or alloy? At any rate, after 180 grit, there's definitely no plating of any sort left on one octave I would expect. Not that I did it profusely, but enough to get just the contact surface facing me clean. I'll have to see if I can pick up some of the Deoxit and try that out before I do something more radical.

    Geo: Thanks for the info. That's the theory of operation I was looking for ...

    Joel

    Edit: Yes TD, you are absolutely right. I stand corrected. SMACK! After closer inspection, the top 1/4" or so of the wire is indeed gold. I checked the ones that I took the emery cloth to and believe it or not, they are still intact! Wow, must be some serious plating. I was extremely gentle when I did it, and lucky, but I certainly won't do that again ...
    Last edited by JoelHof; 06-14-2018 at 05:48 PM.
    Instr: Conn Artist 721 Deluxe, Kawai SR7A, Roland AT-80, Wersi Arcus
    Midi Ctlrs: Arturia KeyLab 49 x 2
    Sftwr: Arturia V Collection 4/5, ZynAddSubFX, Hauptwerk free ed, var. VST's, Ableton Live Lt, Ardour, Reaper
    Comp: Dell Prec. T5500-Win7/Linux Mint
    Need: Behr. FCB1010 Midi Foot Ctlr, Midi Ctlr (Akai APC40 mkII?), Small 8-12 chan. mixer (Mackie ProFX12v2?)
    Want: Leslie's for my SR7 (dreamin' here!)

  7. #7
    ppp Pianississmo JoelHof's Avatar
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    Here ya go ...

    How about this https://emcemi.com/product/conductiv...uded-profiles/

    This company has all kinds of conductive elastomer products including solid round down to 1mm in diameter. Maybe this would work as a direct replacement or are they not conductive throughout the material. I'll have to contact them. There's quite a variety of what they're impregnated with. The second "download brochure" lists all the profiles and materials. Any thoughts?

    Joel
    Instr: Conn Artist 721 Deluxe, Kawai SR7A, Roland AT-80, Wersi Arcus
    Midi Ctlrs: Arturia KeyLab 49 x 2
    Sftwr: Arturia V Collection 4/5, ZynAddSubFX, Hauptwerk free ed, var. VST's, Ableton Live Lt, Ardour, Reaper
    Comp: Dell Prec. T5500-Win7/Linux Mint
    Need: Behr. FCB1010 Midi Foot Ctlr, Midi Ctlr (Akai APC40 mkII?), Small 8-12 chan. mixer (Mackie ProFX12v2?)
    Want: Leslie's for my SR7 (dreamin' here!)

  8. #8
    fff Fortississimo tucsondave's Avatar
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    The conductive elastomer bus bars used in organs had a solid copper wire core (Thomas, Yamaha, Baldwin) or stranded wire as in the Conn.

    td

  9. #9
    fff Fortississimo toodles's Avatar
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    Gold contacts used in organs is not plated, it is clad by a drawing process. Gold won't plate onto itself and the drawing process allows for a useful thickness. Gold plating wears off easily with any real wear. Nonetheless, gold contacts never need abrasive cleaning--gold does not easily combine with any other element.

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