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Allen MOS organ home now and the adventure begins!

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  • #16
    More tinkering this morning -- revised the Celeste Effect. As I mentioned in the video, I wired my "Swell Celeste on Great" tab so that it activated three simultaneous MOS functions -- (1) swell to great synthetic, (2) swell to great natural, and (3) great tuning sharp. This causes any stop drawn in the swell to play on the great as if it were a two-rank celeste. That sounds pretty good, BUT there is a drawback. Simply "double-keying" the same stop creates the necessary pair of pitches, but they both sound through the same audio channel and thus create some of that "out-phasing" that makes it sound fake or electronic.

    I realized that if I removed the #1 item (swell to great synthetic), I could make a better celeste, actually a very authentic celeste, like this:

    The tab now activates only TWO of the MOS functions -- swell to great NATURAL and Great Tuning Sharp. Here's how I use that to create a nice celeste:

    (1) Turn on the swell Gemshorn.
    (2) Turn on the "Swell Celeste on Great" tab
    ....... At this point the Gemshorn plays on the great at normal pitch. Doesn't sound any different from playing it on the swell.

    (3) Now turn on the Great Hohlflote, and you will hear an awesome celeste!

    Why is this so good? Because what you hear will be two completely separate stops, at separate pitches, playing in two separate audio channels, like this:

    The Gemshorn, coupled down from the Swell via the NATURAL coupler, sounds through the Main audio channel. It sounds at NORMAL pitch, because when you couple down with the NATURAL coupler, the coupled stops do NOT take on the pitch of the great division.

    And at the same time, you hear the great Hohlflote sounding through the Flute audio channel, and it sounds at a SHARP pitch because the celeste effect caused the tuning of the great division stops to be shifted upward by a few cents.

    Unfortunately, the limit of six keys down at a time still applies...

    When I get around to posting the "how-to" on the new MOS Hacks thread, I'll show exactly how this is done.

    Ok. Back to practicing!
    John
    ----------
    *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

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    • myorgan
      myorgan commented
      Editing a comment
      Thank you, John for sharing that. Do you have a recording of post-correction stops? I'm all about comparisons.

      Michael

    • MarkS
      MarkS commented
      Editing a comment
      How about the Gedeckt and Dulciana as a poor man's flute celeste?
      Have you tried Chiff coupled to the Prinzipal?

      I look forward to hearing the 32' stops.

    • jbird604
      jbird604 commented
      Editing a comment
      Michael -- I'll make you an A/B recording tomorrow if possible. I can still do it either way, as I only disconnected the synthetic coupler from the celeste tab. I can turn on the synthetic coupler with the tab that is already there and demo it in that mode, then do it with a swell stop played against a great stop, which is the way I'm currently liking it best.

      Yes, Mark, there are numerous pairs that make good celestes. I like the swell Gemshorn with the great Hohlflote, but it could as easily be the swell Gedeckt and the great Dulciana. The key is to use a "flute" stop on one manual and a "main" stop on the other, to keep the two ranks in separate audio channels.

      I am quite interested in enabling the 32' stop. Thinking of moving the wire from one of the other pedal stops to the Contre Bourdon pin. The speakers I'm using probably can't do the 32' stop justice, but it might still add something nice. We'll see.

  • #17
    MIDI converter from Harrison Labs is on the way.... There is a VPO in my future!
    John
    ----------
    *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

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    • #18
      And the adventure begins.

      Comment


      • #19
        Yes, I'm souring on this organ in record time! Usually I keep an organ at home for at least a few months before I decide it's not going to cut it for me. No, I'm not putting it on the curb, but I am going to get that HLabs board wired in as soon as it comes, and turn to something else, almost anything else, for a tone generation source!

        Under normal circumstances an old MOS organ should be adequate for practice. There are 38 available speaking stops, selected for playing just about any type of music from any period or style. Full complement of principals, flutes, strings, reeds. Proper mixtures and mutations. And no unification or borrowing at all. You have to hand it to old Jerome Markowitz -- 50 years ago he chose the ideal stoplist for a small but adequate American organ.

        A perfectly compatible AGO console with highest quality keys and pedals, sturdy and nicely finished case. Everything about the hardware says this organ was built to last a very long time. I'm even fine with it not having a roll top cover or other external features that aren't essential for playing.

        The most obvious shortcoming is the sound, which is of course very primitive compared to a modern digital. Such as my R-230, with distinctive attack parameters and transients for each stop, multiple samples across each rank's scale, unique tuning curves for each stop. Nothing here to make you say "wow, that sounds like pipes," unless you're listening to a single note of a single stop, which may actually sound quite convincing when heard by itself. It's not just that its sound is un-pipe-like; it's also pretty un-appealing, lacking that warmth or sweetness or something that would make you fall in love with it.

        And I think it's that very bland and BLAH sound that has convinced me to start working toward a VPO. I finally have a decent console that is worth preserving -- with native voices that are truly not worth keeping, not a single one of them! Perfect for conversion purposes. And with the HLabs board, I will instantly get MIDI OUT key data on all three divisions without much work -- apparently there are 15 or 20 little wires to solder to specified points on the KBA board, best I can tell from the HLabs info. That's a lot less work than soldering to 61+61+32 contacts individually.

        I guess in truth I'm not so much an organ PLAYER as I am an organ TONE-LOVER. The joy of playing, for me, is not so much in mastering new pieces as in creating TONE that thrills me, that I think others will enjoy.

        So yesterday I used the MOS to record a pair of Sunday hymns to share with my scattered church folks via YouTube. And when I got through and listened to it, I was deeply disappointed in the TONE of the organ. Instead of crisp and beautiful and rich and exciting, it just sounds wimpy and plain. It shouldn't be that hard to get a VPO up and running, even with a meager computer and free software, that will blow this MOS away. We'll soon find out...
        John
        ----------
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        • samibe
          samibe commented
          Editing a comment
          Every time I visit my mom and play her MOS, I'm a bit disappointed with how plain it sounds. There are so many stops and a decent amount of variety among the stops (or at least the names make it look like it) and yet it if more than 4 stops are used on a division it just gets muddy and boring. I have an ADC and it can sound fairly sterile but I sure miss it when I'm playing the MOS.

      • #20
        Here's a link to the recording I made for my church. Pardon the hoarse-throated singing (it's allergy season, hopefully NOT a sign of COVID). I pre-recorded the MOS with a direct to digital setup, then played it back through the Lexicon and speakers while we sang along, so this is truly how it sounds in the room. Typical hymn-singing registration, and a bit of my "Faux Festival Trumpet" in places.


        John
        ----------
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        • tbeck
          tbeck commented
          Editing a comment
          That was just about the tempo we used in our Southern Baptist church back in the day when they still sang hymns.

        • myorgan
          myorgan commented
          Editing a comment
          Interesting that tempo became the topic of discussion. When I played at University (6,000+ in chapel), we would take it at a slightly faster pace. People followed or got left behind. The pianist/organist heard the people singing about 1/4 to 1/2 second after they sang, so we had to leave them behind or end up in our grave by the end!

          At my current church, I play the first hymn in 2/2, and insist the people enunciate the running 8th notes on the seond hymn. There are times when good articulation allows for a more live tempo. OTOH, when I visit my relatives in the Southeast, invariably, those tempi are slower than what I use at home.

          Michael

        • jbird604
          jbird604 commented
          Editing a comment
          I just listened again, and I can certainly see how it might well should be sung faster than that. I'm sure I was trying to be a little more cautious and ponderous that I am in an actual service, since mistakes that would be ignored in a service are so terribly obvious in a recording.

          I probably have a tendency to play a lot of hymns more slowly than necessary, as I'm often "hearing" them in my head as if I were playing in Westminster Abbey!

      • #21
        “t could even be that my little organ nook has some resonances that cause it to favor certain notes”

        John I’ve seen many references over the years to your “organ nook”. Here’s an idea for you. I notice in the photo that your nook has a window, thus an outside wall. A man of your talent deserves more space. You could push that wall out and make it an organ bay (Similar to bay window). Addition space with depth of 3 to 4 feet is easily attainable. With the additional space you could move in a three or four manual Big Bertha and have plenty of room for speakers in the remainder of the space. Just sayin’ as we have time on our hands.
        Sam

        Allen ADC5400, Allen ADC4000, 1910 Chickering QuarterGrand
        Past---Galanti Praeludium II, Yamaha Clavinova, Hammond A102, W.W. Putnam Reed Organ

        Comment


        • jbird604
          jbird604 commented
          Editing a comment
          Thanks for the suggestion. Yes, it could be done, and I do have time on my hands these days.

          In truth, what NEEDS to happen is for me to move the big ugly clunky desk out of this nook. It is a big old home-office type desk that takes up more of the floor space than the organ console does. If it were gone, I'd had plenty of room and could even orient the speaker differently, perhaps get rid of the resonances.

          And there is hope for that idea -- now that the kids are gone and hardly ever need to spend a night with us, we could move the desk into a spare bedroom. In fact, I should make that a goal during this shutdown period.

          So maybe that will happen. Thanks for giving me something to think about.

      • #22
        Well, it's Thursday, so the calendar says... What difference does it make any more? In a normal year I'd be looking forward to a marvelous Maundy Thursday service, possibly my favorite evening of Holy Week. But that virus... So, I'll do a little more speculating and wishful thinking about my soon-to-be-real MIDI organ project...

        The Harrison Labs MIDI converter is supposed to arrive tomorrow, and the MIDI Solutions 4-to-1 merger should be here on Saturday. Perhaps by early next week I'll have the old gal ready to plug into something. Then I'll be able to try out several new sources of organ tone...

        There's the Content 220 unit, with a barebone set of stops, typical of a minimalist 2m organ. Sound is surely a step up from MOS, but unexciting.

        Then there is an Ahlborn Archive module at the shop. I once built a complete organ for a customer with the "201" model of this series, and the sounds were quite good to my ears, though that was 20 years ago. Nowadays I'm not sure how it will compare to other digital organs.

        The one I have is the "Classic" version. Great = principal 8, two 8' flutes, a 4' flute, an Octave 2' and a Cymbal III. The Swell = Gemshorn 8 and its celeste, 8' and 4' flutes, Plein Jeu IV-V, 16/8/4 chorus reeds, a solo reed, and a Festival Trumpet. Pedal is oddly just a string at 32 and 16 and a reed at 32 and 16.

        This module was obviously intended to SUPPLEMENT an existing organ, freshen the sound, add some excitement. Perhaps it's just the ticket to add some needed sparkle to the tired old MOS stop list. I'll have to at least try playing the MOS and Archive stops together and see how that works. A little awkward, like playing two organs tied to a single console, I suppose. But it could work.

        And there's the Hauptwerk route, my eventual goal. I have the free version of H-4 installed on my everyday laptop, along with three free sample sets I've picked up. All three sets have rather decent 2m stop lists and of course they seem to sound much more authentic than any ordinary digital organ. Drawback is that I don't have a dedicated computer to do this with, so it would be a pain to swap the laptop back and forth from desk to organ. I'll try it out, but most likely won't make the leap until I'm ready to buy a complete new computer, complete with a large touch-screen monitor, just for Hauptwerk or GO or whatever.

        Anyway, it could be FUN. And there's none of that pesky paying work to distract me...

        John
        ----------
        *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

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        • #23
          Hi John,

          Your bringing up the Ahlborn Archive got me thinking I could add to the narratìve here.

          The Ahlborn modules came out in the mid 90s, in four flavours. They were Romantic, Classic, Archive 201 and Archive 202. You were quite right in saying these units were a supplement to an organ. The Archive 201 is closest to being a stand alone unit. Tonally the Classic is closest to the Chronicler sound, of A-G line of organs.
          The Archive units were good sounding, especially if good audio was used, and the audio was modified to 6 channels out. The internal audio was setup the same as A-G organs, each division having a left and a right out. From the factory, they just had a L and a R out.

          These Archive sold quite well in their day, as pipe organ builders found them very useful for 32' stops, Festival Turmpet, Tubas, etc.

          There were also 2 customized specs, that were cirulated. One was called Silbermann, which had baroque samples from a Silbermann organ, and the second one was called Cavaille-Coll based on a C-C organ. I believe Ahlborn Orgeln in Germany developed these specs. These specs were rougher sounding than the native General Music specs, but were useable.

          Further customization was possible,to the point of stand alone, but has not been done recently.

          These modules did sound better than the Viscount module from the late 90s.or the Content one, or the Johannus add on. Perhaps the best simple MIDI add on for organs was the MX-200 Rodgers, based on a Roland Module. The Viscount CM-100 was also used to augment pipe and digital organs.


          If you have one of these, make sure to check the battery. It is located on the CPU board. The battery has a habit of leaking battery acid onto the CPU board, making a mess of the traces and components located nearby. Battery should be changed at least every 10 years.

          There are still pipe organ builders and those wishing to augment their digital organ, but really the market for them is pretty much gone. Would cost too much to , for such a small market.

          AV
          Last edited by myorgan; 04-09-2020, 12:10 PM. Reason: Remove extraneous line returns.

          Comment


          • jbird604
            jbird604 commented
            Editing a comment
            Arie,

            Thanks for the heads-up on the battery. I'll open it up and check that right away. And I enjoyed the extra info on the modules. I wasn't aware that they could be modified to give six channels out. That would be an interesting exercise, should a person be building up an organ with one of these. (My current plan is to stick with my two-channel audio and simply mix the Ahlborn and/or the Content with the MOS sounds using the mixer I have.)

            Shame that the market dried up for these modules. They were very nice. The 201 that I used was just right for creating a simple organ for a small church. They had an historic old console that they wanted to preserve, though the innards of it were shot. I MIDI'd it up and added an encoder from somewhere that interfaced perfectly with the Ahlborn module, turned on the stops individually from the old organ's drawknobs.

            Nowadays of course the market for all things organ-related has shrunk. And the software generators such as Hauptwerk and the various free ones have certainly mopped up a good bit of the market for organ expanders.

        • #24
          I spent two or three hours working on my setup yesterday. Got the Harrison Labs MIDI converter connected to the Allen KBA board. There are "only" 20 small wires to solder to tiny little traces on the KBA. At least they're color-coded.... I probably should've paid the extra $99 and had them do it. I'm getting too old for this sort of thing. My vision isn't the best, and my hands aren't as steady as they used to be. But I got it done, and it actually worked the first time! Not terribly difficult, just tedious.

          The MIDI Solutions merger came in as well, and I got it connected to the three outputs of the HLabs unit. It works too, though curiously the MIDI activity light seems to be blinking nervously all the time, as if some MIDI message is being generated in brief rapid pulses. Makes the MIDI dot flicker on the Ahlborn too, but doesn't create any sound. I'll have to investigate that further.

          The output of the merger goes to the Ahlborn Classic module. As Arie V mentioned above, the battery needs replacing. It will not hold the settings overnight. I'll have to attend to that right away. When I turn it on, I have to begin by setting the MIDI channels, as the default comes up (with pedals on channel 4 instead of channel 3, as is Allen's standard). The preset buttons of course can't be saved either without a functioning battery.

          The sound of the Ahlborn is intriguing. There is no denying it is far and away better than the MOS sound, even without any attention to voicing. As I understand the manual, there is a great deal of adjusting that can be done to each of the 20 stops -- level, tuning, tone color, articulation, etc. So I'll have to work on that, once the battery is changed so it can save my work.

          I have drawn myself a diagram of how I can integrate the MOS and the Ahlborn sounds and have the Allen expression pedal control them both. I'll need to solder together a custom cable to make the expression work with the line level audio, but I know how to do that. Just have to get to it, as soon as Easter is past.

          Another project for the shutdown period is to get my organ nook "enlarged" by getting the big desk moved out of it and into the spare bedroom. That will give me room to bring in some better organ speakers, perhaps a pair of HC-12's, to better project both the Allen and the Ahlborn tones, and hopefully my future VPO sound.

          Photos and videos will surely follow, but first I've got a Zoom session with my church folks and a Hangouts visit with the children. So maybe tomorrow...

          Happy Easter!

          John
          ----------
          *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

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          • #25
            Today I spent some more time on the project. In order to implement my unified expression scheme, and to put a stop to the turn-off thumps I've been experiencing from the outboard audio equipment, I decided to take the back off again and run all three RCA connections going into the back of each amp out to the external rack I'm using.

            So now there are six shielded cables coming out the back of the console (in addition to the MIDI cable and the power cord). Two for the flute and main audio signals, two for the pair of expression cells, and two for the mutes. I'll be making up a couple of custom cables tomorrow to finish integrating everything.

            The two audio signals of course go directly into my little mixer. The two mutes go to some "Y" connectors and are in parallel with the input jacks of the stereo power amp. There they function just like they did inside the Allen console -- they short the amp input to ground for a few seconds at turn-on and instantly at turn-off, thus preventing the transient noises.

            The expression cables will have to be modified by cutting them and putting in a series capacitor of about .22 mfd so the expression will primarily affect the higher frequencies and leave the bass nearly unchanged, as is desirable on an organ. I must also make a pair of custom output cables for the mixer. The signals coming out the mixer are at line level and low impedance, so the expression would have little to no effect on them. I'll make up a pair of cables with about a 47K ohm series resistor in each one, then I'll "Y" together the end of each cable with its expression cable before it goes into the Lexicon.

            With the Ahlborn module connected to two other inputs on the mixer, the entire system will now express together without having to use MIDI to send expression to the Ahlborn, or having to modify the Allen expression shoe. I'll be able to play the whole thing as one unified organ... or not...

            Speaking of using the MOS tones and the Ahlborn tones together.... Well, today I've taken some time to play around with my "hybrid" organ, and pretty much feel that the old MOS stops are not worth saving, except possibly the pedal stops, since the Ahlborn Classic module lacks the most important pedal stops. I've been using one or more of the MOS 16' pedal stops (and sometimes the 32' stop I added), and coupling the Ahlborn's great down to the pedal. Then I can make up a nice manual ensemble using only the Ahlborn's great and swell stops.

            I have tried playing the MOS stops along with the Ahlborn's, but there really isn't any comparison in quality. The old MOS tones are so drab and sterile and downright ugly by comparison, they stick out like a sore thumb, even in full registrations. I have a feeling that I'll mostly do without them, other than the pedals, and probably hasten my conversion to a VPO.

            Anyway, I hope that I'll get the expression finished tomorrow and can then do some serious playing and perhaps make a recording to share.
            John
            ----------
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            • #26
              Here's a little demo of the Allen MOS sounds, then with effects supplied by the Lexicon, then some samples of the Ahlborn sound. Even a little bit of combined MOS and Ahlborn. Very ordinary demo here, but perhaps you may find the contrast between the two types of digital sound interesting. It's even possible I'll find ways to use the two types of sound together, once I figure out what works.


              John
              ----------
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              • myorgan
                myorgan commented
                Editing a comment
                John,

                As usual, great playing.

                The ending registration sounded a bit bright (laptop speakers), however, I realize that if the organ were placed in a church setting, the sound would just have the right amount of treble to cut through the congregation singing.

                I'm not sure if you realized it or not, but the initial comparison you made between the MOS 8' was with the Ahlborn 8'+4'. It might have made a bit better comparison if both had used the 4'. Also, was the balance control set to Bright or Mellow on the MOS? I'm also wondering if that bright vs. mellow control affects the Ahlborn as well (using the Allen speakers) or if it has its own speakers.

                Now I'll have to break out my Expander!

                Michael

            • #27
              Listening to this tells me that the Ahlborn stops seem to need less reverb than the MOS, for some reason. I noticed that the tone got pretty muddy when I turned on the plenum registration of the Ahlborn, and I think a lot of that comes from the Lexicon being over-done. I'll need to tweak that for sure. Wish I had made this recording without any reverb at all. Would've done a better job of revealing the tonal differences. Next time I'll do that.

              Right now it's also apparent that there is a tuning discrepancy between the MOS and the Ahlborn, though I don't know why. The MOS was tuned exactly A440 when I set it up, in order to match the piano sitting beside it. And the Ahlborn has a tuning menu, and is set for 0.00 variation from standard. But there are some intentional offsets in tuning among the stops, and it may be that something I'm using here is pretty far away from A440.
              John
              ----------
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              • Larrytow
                Larrytow commented
                Editing a comment
                Here's a quick thought on the tuning issue you refer to between the two : Could the Ahlborn be set to a different temperament ? I'm not even sure I'm hearing the issue though, so that is just a WAG.

              • jbird604
                jbird604 commented
                Editing a comment
                Set for equal temperament, but there are several other menu items that alter the tuning. One is the "chorus" setting, which I believe adjusts the base amount of pitch offset among the various ranks. And in the manual I read that there are individual adjustments for each rank that also vary the amount of detuning. Once I have it fully functional I'll have to use my tuning program to measure the cents deviation of each stop, and will probably pull them all a little closer to normal. I'm not crazy about sour tuning, though I understand why the default could be like this, in order to guarantee that the sound wouldn't be "sterile" or "too perfect," as many people used to criticize electronic organs on that point.

            • #28
              One tends to forget that digital organs have improved vastly over the decades since the first MOS in 1971. Yes, that first MOS was an exciting development, with tones that seemed so "real" and so much closer to pipes than anything we'd heard before. But hearing it now we tend to judge it as primitive, and it was.

              As samibe noted above in a comment, you can't use very many stops at once without the sound turning muddy and indistinct. The larger MOS organs sound better, as the "doubling" effect covers a multitude of defects. A MOS installed in a lively church gets greatly juiced up by the acoustic. And the MOS-2 organs as a rule sound better than MOS-1 due to the incremental improvements and the numerous previously "optional" features that became standard at that time.

              I can't forget though what a vast improvement I heard with the very first ADC models. To my ears, in 1984, Allen had NAILED IT with the new series. So many things got better. Mixtures finally sounded right, chimes and other percussions finally sounded realistic instead of fake, every organ had real celestes, chiff was much improved, there was a subtle tuning offset within each division between 8' and 4' members of every chorus and between the primary 8' stops. Couplers worked much more like real couplers, at least on all but the smallest models (the MADC models still used "synthetic" coupling somewhat like MOS).

              Then MDS models came along with MIDI, and even the smallest models had that wonderful "wind" that Allen had teased us with in the final ADC iterations. MDS sound didn't seem much different, but with all of ADC's deluxe options now standard, such as digital reverb, it was even more fun to play. Renaissance technology eventually emerged, with greatly increased voicing capability, simple "reverb" giving way to more realistic "virtual acoustics" and then "Acoustic Portrait." DOVE was a bit obtuse, but at least showed that true custom voicing was possible now, and that extremely detailed and meaningful adjustments could be made in the sound of each rank.

              While some of the series transitions are not as striking as the MOS-to-ADC changeover, comparing organs that are 10 years apart in production will usually convince me (or anyone) that the changes were worthwhile.

              So I made a nearly 40 years jump BACKWARDS between last October and now, letting my fabulous R-230 go and bringing home this old dog. This has been something of a shock to my ears!

              But now I'm determined to make my home organ OBSOLESCENCE-PROOF by going all the way to the VPO. Of course I've wanted to do this for a long time, but I resisted because I usually had some kind of decent hardware organ at hand, and I appreciated the instant-on operation and the no-tinkering situation. And I didn't really have the time, I was staying so very busy in the service business.

              The time is finally right. This old Allen console isn't exactly just like new, but the keyboards are in great shape, the contacts don't give me any trouble at all, the pedals are superb, and it looks good enough. And once I start gutting it, I won't have lost anything at all of value! The old Allen photocell expression system is still as useful as it was 60+ years ago when Allen developed it, and there isn't any capture action that I'll have to leave behind or accommodate with a VPO. I'll probably just remove the old tab rail and make way for a touch screen.

              But right now, I'm creating this interim solution -- leaving the MOS intact while adding the Ahlborn stops. I think it will be ok for a while, but I realize the only thing I have to do now is get a computer and touch screen monitor, and swap them out with the Ahlborn. I've never been so well prepared to "just do it." The audio system I've rigged up to combine the MOS and the Ahlborn will work well with the VPO, no further changes necessary until I want to.

              I also realize that I've let my actually organ PLAYING slip a little, with no church services to prepare for. So I've got to get back to that right away. Today I hope to make up the final bit of cabling I need to get the expression operating, then I'll be at a good resting place while I use what I have and make my plans to do the VPO thing before too long.

              Thank y'all for listening!
              John
              ----------
              *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

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              • #29
                Well, one thing didn't go just right... As planned, I tried connecting the expression to the audio signal post-mixer, just before it goes into the Lexicon, so as to express both MOS and Ahlborn sounds. Got my custom expression cable made up -- a standard stereo RCA patch cord, cut in the middle, with a .22 mfd cap inserted in series into the signal conductor. The shields were reconnected, and I even wrapped foil around the area. Looked so good to me!

                Well, yes, expression works as it should -- higher frequencies affected the most, bass not so much. I'd made another custom cable, an RCA stereo patch cord, also cut in the middle, this one with a 22K resistor inserted into the signal wire. Turns out that 22K is just right for converting line level audio down to a signal that the Allen expression cells can work with. So, with my 22K of resistance at the mixer output, and the expression Y'ed into the line at the Lexicon input, the volume goes up and down as it should with the shoe. But....

                Allen must use some kind of heavy-duty super-shielded audio cables in their organs, and my cables are cheap ones from MCM or somewhere. With my expression came an unacceptable level of HUM. I've heard worse, of course. We all have, on some old tube-type equipment that was about ready for some new caps. But I'm not satisfied to have a constant almost-"B" note playing along with me, like a soft cipher.

                So I unhooked my expression system, in spite of the work that went into it. To make it work, I'd have to build it again out of better cable, I suppose. I can't find any other reason why it hums like that.

                Now I'm just going to play for a few days with no expression control. I have the mixer on a stand right beside me, so I can set the volume where I want it with the master slider. That will have to do for now.

                The Harrison Labs MIDI converter has screw terminals for attaching expression controls, and says it will work with Allen LDR's. Once I recover from this expression disaster, I may go ahead and figure out how to connect up my expression cells to the HL. That would only give me expression on the Ahlborn, as the MOS of course doesn't respond to MIDI. But I'm leaning toward an early demise of the MOS system as a tone source...
                John
                ----------
                *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

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                • #30
                  I know I'm crazy for posting all the gorey details here, but I don't have anybody else to talk to about this! Though frustrated by the failure of my expression plan, I did get back to playing the organ today, and it's perfectly ok, at least for now. I will probably go fully VPO pretty soon though, just to get rid of the pile of junk accumulating around the console!

                  The Harrison Labs MIDI converter board was fairly easy to solder to my KBA, and it worked from the start. But I immediately noticed that the MIDI activity indicator flickers rapidly on any device I attach to the converter. To see what's happening, I connected the converter's output to my laptop, running MIDI Monitor, and discovered that MIDI Controller #123, value "0" is being continuously generated on all three channels coming out of the converter board. Controller 123 is "All Notes Off" but it doesn't seem to cause any problems. The Ahlborn plays normally, as does Hauptwerk 4. But the flickering indicator is annoying and slightly worrisome too.

                  I just now sent an email to Harrison Labs to ask if this is normal, or if it indicates a problem with my KBA or with my soldering, perhaps. We'll see...

                  But yes, if I went full VPO, I could get rid of ALL the RCA cables coming out of the console. Nothing would have to come out except a single MIDI cable and the power cord. I could also get rid of the mixer, as the output of the computer could go directly to the Lexicon. And from the Lexicon straight to my amp and speakers. Simpler is better, and less likely to pick up any of that annoying hum.

                  Well, that's how it is on the afternoon of April 15 2020. More to come!
                  John
                  ----------
                  *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

                  https://www.facebook.com/pages/Birds...97551893588434

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                  • myorgan
                    myorgan commented
                    Editing a comment
                    John,

                    Just keep all the systems intact and compare as you go down the road. If you have my luck, you'll want a stop only the Allen has, and won't have it if it's clipped. Just sayin'!

                    Michael

                  • AllenAnalog
                    AllenAnalog commented
                    Editing a comment
                    You have an audience out in Colorado for your experiments. Keep the progress reports coming!

                  • tbeck
                    tbeck commented
                    Editing a comment
                    Michael, even if he does find one stop on that MOS that he would like to keep (which seems unlikely), it will be very difficult to blend it into the reverb environment of any given sample set.
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