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  • #31
    I left the 5k pot as it is not a significant load to a low impedance output from an audio interface. I wouldn't go higher than 50k in any case.
    EDIT: The typical output impedance of an audio interface is around 100 ohms.
    http://www.kinkennon.com

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    • #32
      I have successfully modified three amplifiers using John Kinkennon's photos as a guide so far:

      2 x -6 model amplifier
      1 x -7 model amplifier

      I have not replaced the POTS ... the one on the -7 looks like it has 5K etched into it... the others only had model numbers that I could not find any specs for.

      I've tested both -6 amplifiers in the church and they are no longer hissing and I think that the output will be sufficient for our needs.

      Note that the -6 and the -7 models both looked essentially the same on the inside. I peeked inside some of the other models and they look substantially different... so I'll wait with those for now.

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      • #33
        Folks,

        I kept looking at this thread, trying to determine what amplifier code I needed to purchase to restore some missing channels on my Allen ADC-8000 DKC. Unfortunately, I could never narrow it down.

        Yesterday, I took a peek inside the storage unit to look at the extant amplifier rack, and all the S-100 amplifiers I could see were Code 3. So, for posterity's sake, I'm posting here that for an ADC-8000 DKC (& presumably any other ADC-x000 organ), the amplifier racks use S-100 Code 3 amplifiers.

        I hope this helps someone else in the same situation determine what they need.

        Michael

        P.S. I do know Allen D-40 amplifiers were an option for some channels in this organ, but I'm trying to go for all S-100 amplifiers.
        Way too many organs to list, but I do have 5 Allens:
        • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
        • Lowrey Heritage (DSO-1)
        • 9 Pump Organs, 1 Pipe Organ & 6 Pianos

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        • myorgan
          myorgan commented
          Editing a comment
          WOW! I can't imagine what the Allen techs were thinking. I have to admit–I've never seen an indication of a code ANYWHERE on any of my amplifiers (over 40 in all the organs I have). All I've ever seen is the -x revision number you referenced.

          I guess in that case, I need to stop buying off *Bay because one never knows what (s)he is getting. Grrrr. What a shame. At least the D-40 is straightforward.

          Michael

        • jbird604
          jbird604 commented
          Editing a comment
          Well, don't give up entirely. Yes, the D-40 amps are all usable with ADC organs, though you should avoid buying one that was salvaged from one of the old MDC series if it has the special 29-volt output for powering a pre-amp. I think those amps had a quirky input impedance, so they would probably work, but might have a different sensitivity than standard D-40's.

          And you can always buy ADC modular amps (the common dual, triple, and quad amps that were used in nearly all ADC models after about 1985). They will be code 13, whether or not marked as such.

          And if you see an S-100 and it has "-3" at the end of the part number, it is also code 13.

        • myorgan
          myorgan commented
          Editing a comment
          Thanks for the reassurance (& caution), John. I did purchase a couple of D-40 amplifiers off *Bay, but I didn't know to check for the 29V output you reference–not that I would even know how. Thanks again.

          Michael

      • #34
        That's interesting...I resurrected an Allen ADC4500 that had the internal amps removed. The spec called for one D40 and two S100 amps, which I had. Never paid attention to that DC output. I did wonder what it was for? Now I know. But how could that cause problems, as it seems to work Ok?
        Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

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        • jbird604
          jbird604 commented
          Editing a comment
          I don't know that the presence of that 29 volt output keeps it from working in an ADC organ, just signifies that it is one of the D40's made for the early MDC models. The audio systems in those early MDC's may be quirky. These models came out right near the end of the MOS era, and were the first ones from Allen to use "line level" audio rather than the low levels used in analog and MOS models. I have read somewhere in the Allen literature that they transferred audio in the MDC models on a high-impedance circuit rather than on the lower standard impedances found in ADC models and all true line level audio equipment of today.

          That MAY mean that the volume pot on these special D40 amps is of higher value than the later D40 amps used in ADC organs, which MIGHT make them a little more sensitive. But all this could be a red herring and have no effect whatsoever on their audio operation.

          Be aware that the 29 volt output is on the same screw terminal block as the speaker outputs, so be sure not to accidentally connect the 29 volts DC to one of your speakers, as it would probably go up in smoke right away!

          If you can tell us that the D40 you are using has the 29 volt output and still works perfectly on your ADC, then that is good enough for me. I was just putting out the word that there does exist a slightly different version of the D40 out there.

        • John Vanderlee
          John Vanderlee commented
          Editing a comment
          I found out indeed that the D40 with the 29VDC works fine with the ADC4500. Plenty of range of the volume.

      • #35
        I'm trying to help out a church with a faulty AT6 organ. I'm pretty sure this M5 amp is bad but having problems finding a replacement. Any suggestions would be appreciated.

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        • myorgan
          myorgan commented
          Editing a comment
          I believe there is one available on *Bay right now.

          Michael

      • #36
        Originally posted by Ample Issues View Post
        I'm trying to help out a church with a faulty AT6 organ. I'm pretty sure this M5 amp is bad but having problems finding a replacement. Any suggestions would be appreciated.
        I see the one on *Bay. Realy wondering if there is an amp with a different model # that would work as a direct replacement in this organ.
        In the original post for this thread JBird604 was talking about specific codes being interchangeable

        Comment


        • Ample Issues
          Ample Issues commented
          Editing a comment
          First time posting on a forum. I guess I should have commented on my original post instead of quoted...

        • myorgan
          myorgan commented
          Editing a comment
          Ample Issues,

          No problem. We got the point anyway.

          This thread specifically discussed the older amplifiers & codes Allen used for their earlier organs (MOS, MOS-2, early ADC, later ADC, and early MDS). The D-40, S-100, and AM-100 were used for many different genres listed above, but with modifications for each specific technology (i.e. a pre-amp circuit either present or missing–depending on genre, or expression controls).

          The M5 was not discussed because it is the same technology (I believe) in every application where it is used. The same is NOT true of the earliest digital technologies.

          Michael

        • you795a
          you795a commented
          Editing a comment
          All M5 amps are the same with one exception, 110 volt and 220 volt.. The only difference is if they are 110 volts the front is black and if they are 220 volt the front is green. Other than that they are the same. There were no revisions to the M5 amp. The one on Ebay that I saw was manufactured in 2006 and the one in your photo was 1999. It should be a direct replacement.
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