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  • Attenuator Relay??? (Allen)

    Can someone explain to me what an "Attenuator Relay" is? I've made a few posts recently about an Allen MOS1 632 that I acquired for my church. I've been trying to get the HLabs units to work (to no avail) and when I connect them all up, I get sound out of the Swell (though it has no "effect" (reverb) on it), but I get absolutely nothing out of the Great or Choir. When I bypass the HLabs units, everything comes back like it's supposed to.

    I contacted Stan at HLabs and he looked over the attached picture and said everything looks fine (except the placement of the "Expression Pedal Isolators" which he said would not be causing the absence of sound) but he was "puzzled" as to what an "attenuator relay" was. (See attached pictures....)


    Here is the signal flow starting with the RCA out's on the DAC's, both of which are labeled "DAC2" in the organ for some reason.

    - The RCA cable goes FROM the DAC to the INPUT of the TWG.
    DAC -> TWG

    - The output of the TWG goes to the INPUT of the DSP.
    TWG -> DSP

    - The output of the DSP goes to the Attenuator Relay?
    TWG -> Attenuator Relay


    I am wondering if there is some sort of modification that could have been done on this organ to bypass one of the DAC's or something. I'm wondering why they are both labeled "DAC2". There are also a couple of PCB's that are MUCH newer than the others (see the close-up pictures) and I'm wondering if someone could clarify as to whether or not they would have any affect on the above scenario.

    Please accept my apologies for the lengthy discussion I've had over the past couple of months. I only get one day every couple of weeks to work on this, unfortunately.
    Attached Files
    Drew A. Worthen
    www.drewworthen.com

  • #2
    Hi Drew,

    I hope I can be of some help here. I don't know all the answers you are after, but do know some things from working on a 301-B I have here, getting it ready to place in a church.

    You have a two computer organ there, so it is normal that you have two DACs. Makes sense, right ? They are both labeled DAC 2 , because they are both DAC 2 boards, regardless of what computer they are connected to. I think the MOS organs had 1, 2, 3, and 4 versions of the DAC boards, as Allen improved the technology in them as they got more digital expertise as the years went on.

    The attenuator relay you are concerned about is labeled Swell to Great Attenuator Relay on my 301. I think what it does is cut down the audio level of the swell stops, only when you have the swell coupled to the great. Not sure it works that way on your 632 or not ? But I would figure it is probably the same function. Photo of mine attached - one cable is off because I was playing around in the organ.

    The way I understand how coupling works on the MOS 1 organs is that it is not actual manual coupling like a pipe organ would be. It works by the computer (s) regenerating the swell stops, along with the great stops when the manuals are coupled. So, if you hold a note on the great with the swell coupled to it you hear both great and swell stops together like you expect, but then if you also play the same key on the swell, the volume increases because you are playing the same stops again there. Whereas on a pipe organ, you would not hear anything different, because those pipes are already being used.

    I think that attenuator relay is to make sure the computers and amps are not overloaded when the manuals are coupled.

    The manual to pedal couplers work in the normal way though; IE they do not double generate the coupled voices.

    I just put in a Nanoverb on this 301 using the Harrison Labs Expression Isolators, and they work fine. However, I did not do the audio routing the way you did. Stan told me that the Isolators should be on the output of the Last added on device in the chain, just before the signals go to the amps. I think maybe that is part of your issue; having them inserted right after the DACs, but before everything else. I believe they should be on the outputs of the last items in your chain of add-ons, right before the amp inputs.

    On my 301 I have it like this. For the Flute channel - Allen factory wiring: DAC > Swell to Great Attenuator Relay input. My added wiring - Swell to Great Attenuator Relay output > Nanoverb input , Nanoverb output > H labs EXP Isolator > Y splitter, > one leg to S-100 Flute amp input for the Flute channel speaker, and the other leg > to crossover input, crossover Bass output > S-50 amp input for the Bass and Pedal speaker.

    On the main channel it is : Allen factory wiring: DAC > Swell to Great Attenuator Relay input. Swell to Great Attenuator Relay output > Celeste generator input, Celeste generator output > my added wiring - Nanoverb input , Nanoverb output > H labs EXP Isolator > S-100 amp input for the Main channel speaker.

    This is all working well with this setup. The only odd thing I did was to split the Flute / Pedal channel to two different amps and speakers before the crossover, so that I get some Bass / Pedal signal from the Flute main speaker as well as getting the low Bass / Pedal from it's own amp and speaker. In this setup the crossover is only functioning as a low-pass filter for the Bass / Pedal amp, rather than splitting the signal into high and low bands.

    This one is almost ready to go now, but the other day I had a new issue arise. I think the photocell in the expression pedal for the Main channel may have failed. It is full volume all the time now. Probably will replace both of them once I figure out what part # I need, and where to get them. It is not a failed H Labs Isolator, as I swapped them from channel to channel and it is the Main channel that is loud no matter what.

    I've never used the H Labs TWG or DSP, so I can't say anything about them. Obviously Stan is the one who would know best where they need to go in the system.

    I hope this is some help to you, even if it does not solve all of your issues. I'm just an amateur organ tech, not a pro. Hopefully you will get more and better advice from some of our experts here : John, Arie, Admin, George, Etc.
    Attached Files
    Regards, Larry

    At Home : Yamaha Electones : EX-42 ( X 3 !!! ), E-5AR, FX-1 ( X 2 !! ), US-1, EL-25 ( Chopped ). Allen 601D, ADC 6000D. Lowrey CH32-1. At Churches I play for : Allen Q325 ( with Vista ), Allen L123 ( with Navigator ). Rodgers 755. 1919 Wangerin 2/7 pipe organ.

    Comment


    • #3
      I'll start with what I know and then move increasingly to what I don't know.

      DAC2 simply means it is the second version of the DAC board Allen produced. They should be marked the same.

      Is there a Volume Soft tab on your console? If so, it is likely controlling the attenuator relay; however, on my MOS-2 organ the attenuator relays are on the output of the amplifiers, not on the input. How that affects your set-up with the HLabs stuff is anybody's guess as I don't believe Allen did it that way.

      I have no idea what the PCB boards in the pictures are. You're right, definitely not part of the original equipment. Perhaps they're line amplifiers that were added to circumvent the impedence matching problems of the MOS-1 era organs, but I can't tell from the photos.
      -Admin

      Allen 965
      Zuma Group Midi Keyboard Encoder
      Zuma Group DM Midi Stop Controller
      Hauptwerk 4.2

      Comment


      • #4
        Hi again Drew, I'm thinking about your signal routing as you have it now over another cup of coffee, and am spotting at least one thing I would change right off.

        >> - The RCA cable goes FROM the DAC to the INPUT of the TWG.
        DAC -> TWG

        - The output of the TWG goes to the INPUT of the DSP.
        TWG -> DSP

        - The output of the DSP goes to the Attenuator Relay?
        TWG -> Attenuator Relay <<

        I don't think either of those items should come Before the Attenuator Relay. I suggest that you leave the Allen wiring as is until it gets to the leads that ultimately go to the amps. That is where the DSP and TWG should go , as I think both of those affect the audio signals, so they might be messing up the Attenuator Relay by putting them before it. Then on the output of the last item in the chain is where the EXP Isolators go, right before the signal goes to the amp.

        So it would look sorta like this : Allen factory wiring - DAC > Attenuator Relay input, Attenuator Relay output - added wiring > TWG input, TWG output > DSP input, DSP output > Expression Isolator > Amp input.

        Just seems to make more sense that way. To me anyhow.

        This would be for each channel of course. How many channels are you dealing with on the 632 ? Are the DSP and TWG two channels each ? I see you have two of each device there, so I am thinking you have 3 or more channels perhaps ? If that is so, the routing for one or more might need to be different.

        Clearer photos of what you have there would be very helpful.
        Last edited by Larrytow; 09-17-2012, 09:24 PM.
        Regards, Larry

        At Home : Yamaha Electones : EX-42 ( X 3 !!! ), E-5AR, FX-1 ( X 2 !! ), US-1, EL-25 ( Chopped ). Allen 601D, ADC 6000D. Lowrey CH32-1. At Churches I play for : Allen Q325 ( with Vista ), Allen L123 ( with Navigator ). Rodgers 755. 1919 Wangerin 2/7 pipe organ.

        Comment


        • #5
          So what comes first in the signal chain: the Attenuator Relay or the DAC?
          Is it DAC -> Relay -> AMP?
          OR
          Is it Relay -> DAC -> AMP?

          The Attenuator in this organ is labeled "Great-Choir". I never found one for the Swell/Pedal.

          As far as putting the units right before the amplifier inputs on the amplifier rack (which is about 50' from the console), I thought about this from day one, but the problem there lies in those bizarre "gerald" (about half-sized coax F) connectors rather than RCA. I supposed I could just go get some more RG59 RCA Compression fittings....

          I am going to take another crack at this tomorrow (since I managed to have a whopping TWO AND A HALF hours of free-time this week) so I will be checking back in periodically throughout the day to see who else has chimed in. Thanks, everyone.
          Drew A. Worthen
          www.drewworthen.com

          Comment


          • #6
            Originally posted by dw154515 View Post
            So what comes first in the signal chain: the Attenuator Relay or the DAC?

            As far as putting the units right before the amplifier inputs on the amplifier rack (which is about 50' from the console), I thought about this from day one, but the problem there lies in those bizarre "gerald" (about half-sized coax F) connectors rather than RCA. I supposed I could just go get some more RG59 RCA Compression fittings....
            Nothing in the audio chain can come before the DAC. It is the Digital to Analog Convertor. It has no analog input.

            I think you mean Jerrold connector.
            -Admin

            Allen 965
            Zuma Group Midi Keyboard Encoder
            Zuma Group DM Midi Stop Controller
            Hauptwerk 4.2

            Comment


            • #7
              Morning Drew,

              Admin is right, the DAC converts the digital signals to analog audio signals. Looking at your 5th photo you can obviously see that all the RCA connector cords start at the outputs of the DAC boards. From that point on all the signals are audio signals, although they are at weird levels as Allen is known to do.

              Looking at the same photo, I can see 4 outputs from the DAC boards ( 2 from each board ) so would figure you have a 4 channel instrument there. The 2 outputs from the lower one in your photo go to the Attenuator Relay inputs. That relay has 2 outputs as well. It is after the Relay outputs that I believe your added devices should go. Now just what end of that RCA cable you insert the devices at is up to you and how things fit best.

              The top DAC board in your photo shows the RCA cables coming out of it with No Attenuator Relay evident. Obviously Allen did not design one into those audio channels ( whatever the names of them are ), otherwise there would be one right in the same location relative to the DAC board as the lower one is. Allen actually lays things out in these organs in a pretty well organized and straight forward manner, so that it is easy to understand if you follow the cables from where they start to where they end up.

              Now if you leave all the audio cables on the fold out door as Allen made them, that leaves you with 4 audio cables leaving the door at the top edge of it as shown in your photo. It is in these cables that I think your added stuff needs to be inserted. You can do that at either end of those cables, unless there are any added Allen components inserted in them.

              Those 4 cables ultimately go to your amp inputs. The fact that your amps are 50' away and that the cables change from RCA ends to Jerrold connectors, does not matter all that much. You need to find out where exactly the cables change over from RCA type to Jerrold type. Might be a junction block, or it may be some other component that I am not aware of. Or, you may need to cut and them add RCA plugs to those 4 cables to insert the added devices.

              On your DAC boards there should be lettering near each RCA output that identifies what each channel is. IE : Right, Main, Left, Flute, Etc, or some combination of those. That would be helpful to know.

              Hope this is helpful. Check your PMs here too.
              Regards, Larry

              At Home : Yamaha Electones : EX-42 ( X 3 !!! ), E-5AR, FX-1 ( X 2 !! ), US-1, EL-25 ( Chopped ). Allen 601D, ADC 6000D. Lowrey CH32-1. At Churches I play for : Allen Q325 ( with Vista ), Allen L123 ( with Navigator ). Rodgers 755. 1919 Wangerin 2/7 pipe organ.

              Comment


              • #8
                Originally posted by Larrytow View Post
                Morning Drew,

                Looking at the same photo, I can see 4 outputs from the DAC boards ( 2 from each board ) so would figure you have a 4 channel instrument there. The 2 outputs from the lower one in your photo go to the Attenuator Relay inputs. That relay has 2 outputs as well. It is after the Relay outputs that I believe your added devices should go. Now just what end of that RCA cable you insert the devices at is up to you and how things fit best.

                The top DAC board in your photo shows the RCA cables coming out of it with No Attenuator Relay evident. Obviously Allen did not design one into those audio channels ( whatever the names of them are ), otherwise there would be one right in the same location relative to the DAC board as the lower one is. Allen actually lays things out in these organs in a pretty well organized and straight forward manner, so that it is easy to understand if you follow the cables from where they start to where they end up.
                Actually, both DAC's RCA outputs (so a total of four outputs) go into this relay.
                Drew A. Worthen
                www.drewworthen.com

                Comment


                • #9
                  Hey everyone! Just wanted to say thanks for all the help - after less thought and more "common sense," I found my problem. (Isn't that true to life...) The problem that I was running into was that the RCA cables coming OUT of the Swell/Pedal DAC were NOT going to the attenuator relay after-all. They were color labeled the same, but once I followed the cables (which felt like a mile or more inside that console) I found out that they did not go to their color-matching brethren on the Attenuator Relay. So, very frustrating problem was solved with nothing more than a little patience.

                  So, how do I grade the HLabs units?

                  I am not an organist - in no way shape or form - but I do have extensive background in electronics (electronic music, studio recording, engineering, HiFi Audio etc.) and I would rate the HLabs units as B - 80%. I must say, for me, their real charm is their size. It was really easy to mount them inside the console. I mounted the TWG's down by the DAC boards because I can't see myself adjusting them ever again and I put the Reverb units near the top so all I have to do is open the top of the console and I can adjust the Reverb settings fairly easily.

                  Sound?

                  Again, they are decent. DEFINITELY an improvement over the factory sound. My one praise for the sound is the reinforced low-end in the default reverb setting. I actually used a bright reverb on the Great/Choir and a Warm reverb on the Swell/Pedal for the reinforcement of the 16' and 32' stops (which were hardly audible from my vantage point.)

                  I would recommend them for the sake of supporting American business. However, you can do just as good, if not better, by other companies - Alesis, M-Audio, Behringer, etc. providing more control and variable settings, for the $150 price tag. I hope to put some "before and after" recordings on my website in the near future for everyones information.

                  Thank you, again, Organforum.
                  Drew A. Worthen
                  www.drewworthen.com

                  Comment


                  • #10
                    Hi Drew, I'm happy that you got it all sorted out now. The Organ Forum has been a lot of help for me in the past as well. There are lots of folks here that give of their time and experience, to try to help people solve problems.

                    You are quite right, sometimes common sense helps a great deal when tracing circuits. No relay could have only Inputs; that just don't make sense. I learned long ago ( vehicle mechanics 101 ) that just because some wires have the same color code, that does not always mean they are the same circuit.

                    If you would take the time to give us all the exact routing you used to hook all those components together, it would be nice. And also, the solution to your problem will be here in the forum archives then, for anyone else that may have similar issues in the future.

                    Pictures of the finished job would be great too !
                    Regards, Larry

                    At Home : Yamaha Electones : EX-42 ( X 3 !!! ), E-5AR, FX-1 ( X 2 !! ), US-1, EL-25 ( Chopped ). Allen 601D, ADC 6000D. Lowrey CH32-1. At Churches I play for : Allen Q325 ( with Vista ), Allen L123 ( with Navigator ). Rodgers 755. 1919 Wangerin 2/7 pipe organ.

                    Comment


                    • #11
                      Originally posted by Larrytow View Post

                      If you would take the time to give us all the exact routing you used to hook all those components together, it would be nice. And also, the solution to your problem will be here in the forum archives then, for anyone else that may have similar issues in the future.

                      Pictures of the finished job would be great too !
                      Please see the attached diagram. I will try to take actual photos soon. Thanks everyone.
                      Attached Files
                      Drew A. Worthen
                      www.drewworthen.com

                      Comment

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