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  • Allen ADC Speaker Question

    John (et al.),

    Elsewhere in another thread about a MOS-2 705B, you stated:
    Having two speakers on the same channel *should* increase the output considerably, but if they happen to be out of phase with one another, it would have the opposite effect, sucking up the bass like a sponge.
    [snip]
    We all know that there are some quirks that have to be adjusted for if you happen to mix HC-12 and HC-15 speakers on the same organ, but I think you've said that all of your primary speakers are HC-12s, so no worries about that.
    The above statements were made regarding having two HC-12 speakers per channel, connected to a S-100 amplifier.

    Does the same advice hold true when two speakers are connected in parallel on an ADC amplifier? Is it an issue if HC-14 and HC-15 speakers are mixed on one channel? I would think the impedance rules would apply, regardless of the amplifier, right?

    Thanks in advance.

    Michael
    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)
    • 11 Pump Organs, 1 Pipe Organ & 7 Pianos

  • #2
    The HC-14 and HC-15 are the same speaker design, just one is finished veneer and the other utility. On the same channel, same amp, they should be wired in phase. This is regardless of the amplifier.

    The issue is when using a ported cabinet with a sealed cabinet, each with a low cut-off frequency close to the other's. A ported system shifts phase in the pass frequency band of the port, so it shifts out of phase with the sealed system. But phase can also be shifted by physical distance, so wiring in or out of phase can depend upon the installation particulars.

    Comment


    • #3
      Toodles,

      My question was actually more about the increased output having 2 speakers per channel as opposed to 1. I'm sure there may be phase issues, but I'm actually looking for more output for an upcoming performance. The Symphony's speakers are HC-14 speakers, and mine are HC-15 speakers. I'll probably pair like speakers together on each channel, but I'm definitely looking for more sound.

      Thanks for the quick reply.

      Michael
      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)
      • 11 Pump Organs, 1 Pipe Organ & 7 Pianos

      Comment


      • #4
        Michael,

        You are stating this as if you think there is a difference between the HC-14 and the HC-15
        . I don't know if that is your intent. But there isn't any difference in those two types except finish.

        Yes, you will get approximately twice the output if you use 2 speakers wired in parallel on the same amplifier. If they are close together (like stacked or side-by-side) wire them in parallel, in-phase. And it is safe to wire two HC-14's, two HC-15's, or one HC-14 and one HC-15 on the same amp, in parallel. You get double output. You also draw twice the current from the amplifier. It is fine to do this with ADC amplifiers.

        If they are different types, like HC-12 and HC-14/15, then don't use them on the same amp/same channel, regardless of the amp. They have different impedance characteristics that make it a bad idea.

        Toodles

        Comment


        • #5
          "approximately twice the output"

          Just to clarify--that's twice the acoustic power (3 dB increase), which is not very noticeable to the average listener under normal conditions. A factor of 10 increase in power (10 dB increase) is needed to produce an apparent doubling of level to the (you guessed it) average listener under normal conditions.

          Doubling up speakers is not worthless--3 dB can be significant if the first cabinet is nearing its linear limits. And two cabinets allow better dispersion of the sound. But don't think that the organ will magically sound twice as loud.

          Comment


          • #6
            Originally posted by don60 View Post
            "approximately twice the output"

            Just to clarify--that's twice the acoustic power (3 dB increase), which is not very noticeable to the average listener under normal conditions. A factor of 10 increase in power (10 dB increase) is needed to produce an apparent doubling of level to the (you guessed it) average listener under normal conditions.

            Doubling up speakers is not worthless--3 dB can be significant if the first cabinet is nearing its linear limits. And two cabinets allow better dispersion of the sound. But don't think that the organ will magically sound twice as loud.
            A very wise - and completely correct - post. It amazes me how many people who work with amplification equipment every day still do not "get it" that doubling the power to a speaker does not make it twice as loud.

            Tony
            Home: Johannus Opus 370

            Comment


            • #7
              There are other reasons to double up the speakers, and I generally tried to do that in all but the smallest installations back when I sold Allens. Broader dispersion of the stops in a given channel, lowering of potential distortion as the drivers only have to work half as hard for the same output (move half as much air). Definitely better bass with two woofers working in parallel. So in spite of the fairly small "volume boost" (which oddly enough is what Allen called a double set of speakers), I found it worthwhile most of the time.

              As to mixing speaker types, the only combination that is completely wrong is using an HC-12 in parallel with any of the ported cabinets, such as the HC-13, -14, or -15. It's ok to do that IF they are on different channels of the same organ and IF the organ is not a MOS-1. Why? Well...

              With MOS-1 organs (unlike ADC or even MOS-2) the two channels coming off the DAC board are locked in phase. So with a MOS-1 organ if you have an HC-15 on the Main channel and an HC-12 on the Flute channel, you will find that when you play the great principal and the great flute together, the fundamental is actually diminished rather than built up by combining the two stops, especially in the lower octave or so of the keyboard.

              This is because the signal coming off the DAC and out the amp is in phase, but the HC-12 has its woofer wired backwards, so it is "pulling" when the other channel's HC-15 is "pushing" air, thus cancelling part of the bass. The remedy is simply to reverse the wiring on the HC-12.

              This was dramatically illustrated for me just recently when we installed our large MOS-1 603 organ for the symphony to use. We used four HC-15's on the doubled main channels and four HC-12's on the doubled flute channels (because we didn't have 8 of either type). I immediately noticed the phase cancellation in the low end of the manuals, so I reversed the wiring on the flute channels right at the amp rack (since that was easier than getting into the speaker stack). The problem was instantly resolved.
              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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              • #8
                John,

                It seems to be lodged in my memory ( can't cite the reference right at the moment though ) that ADC organs using an HC12 for the bass channel should have the polarity reversed also. My 6000 has 6 HC14s and one HC12 on the bass channel, and it really works well. However that is in a home setting, so that may be part of why the bass is so good ?
                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


                • #9
                  It doesn't hurt to reverse the polarity on any hc12. If your organ has another channel that shares the same FG board side as the 32 footer, it would be important to do so.
                  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

                  Comment


                  • #10
                    Originally posted by toodles View Post
                    You are stating this as if you think there is a difference between the HC-14 and the HC-15. I don't know if that is your intent. But there isn't any difference in those two types except finish.
                    [snip]
                    If they are different types, like HC-12 and HC-14/15, then don't use them on the same amp/same channel, regardless of the amp. They have different impedance characteristics that make it a bad idea.
                    There is a difference between the two types of speakers--they're on separate speaker dollies, and I really don't want to move them around just to prove a point. I'm content to connect two of the same type together.:-B

                    Originally posted by don60 View Post
                    Doubling up speakers is not worthless--3 dB can be significant if the first cabinet is nearing its linear limits. And two cabinets allow better dispersion of the sound. But don't think that the organ will magically sound twice as loud.
                    Don,

                    Thank you for the details. I am certainly not expecting twice the volume, but the last time or two I've used the organ, the conductor is always asking for more--so this time, I'm hoping to be able to give him as much as he wants/needs.

                    Originally posted by jbird604 View Post
                    There are other reasons to double up the speakers, and I generally tried to do that in all but the smallest installations back when I sold Allens. Broader dispersion of the stops in a given channel, lowering of potential distortion as the drivers only have to work half as hard for the same output (move half as much air). Definitely better bass with two woofers working in parallel. So in spite of the fairly small "volume boost" (which oddly enough is what Allen called a double set of speakers), I found it worthwhile most of the time.

                    As to mixing speaker types, the only combination that is completely wrong is using an HC-12 in parallel with any of the ported cabinets, such as the HC-13, -14, or -15. It's ok to do that IF they are on different channels of the same organ and IF the organ is not a MOS-1.
                    John,

                    Thanks for reminding me about dispersing the sound. If there's enough room on stage, I'm hoping to take advantage and parallel the speakers aimed slightly off-axis. There shouldn't be any issue with phase cancellation because they're all HC-14 & HC-15 speakers. I only use the HC-12 on the bass in reverse-polarity.

                    Originally posted by Larrytow View Post
                    It seems to be lodged in my memory ( can't cite the reference right at the moment though ) that ADC organs using an HC12 for the bass channel should have the polarity reversed also.
                    Larry,

                    Your memory hasn't failed since the last time you looked at the back of your HC-12 cabinet where it tells you to reverse the polarity. On all my ADC organs' HC-12 speakers, the note to reverse polarity is posted right on the back. In fact, the most satisfactory bass I've experienced is with the ADC-6000 with an HC-12 on the 32' channel. They felt the pressure in the balcony! The orchestra also felt the vibration through the floor.

                    Michael
                    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)
                    • 11 Pump Organs, 1 Pipe Organ & 7 Pianos

                    Comment


                    • #11
                      The HC-12 is an amazing cabinet. As I reported in another thread, when we set up that MOS-1 organ for the symphony back in the winter, we used four HC-15's (two on each of the Main channels) and four HC-12's (two on each of the Flute/Pedal channels), and even in that 2500 seat auditorium with a large orchestra the organ was more than capable. The amount of bass from those four HC-12's was astounding.
                      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

                      Comment

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