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  • Allen B20 subwoofer

    Were the early B20 subwoofers designed without a port? If so, will 32' stops respond the same as the current B20 with a port. Thanks.

  • #2
    I could be wrong, but I think the B20 was a ported design from the start. However, there was a sub called the HC-20 that was a sealed box. I saw someone recently listing an HC-20 on ebay or somewhere and calling it a B-20, so there is some confusion about it out there.

    The HC-20 was essentially an HC-12 without the crossover, mid, and tweeter, so it was useful for 32' stops. The only time I sold a big organ using HC-20 cabinets, we used four of them in series/parallel on a single 100 watt amp. It was in a very large church, and we got plenty of 32' tone out of those, enough to shake that building! After 25 years or so the foam rotted out and we replaced the foam woofers with rubber-surround drivers. Still sounds awesome.
    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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    • #3
      John,

      I want to downsize the audio for my digital organ. I'm using 2 Allen B-40s and thought I would get enough bass in a home installation using one Allen B20. You are correct about seeing the HC-20. Do you think the HC-20 would be satisfactory or should I keep searching for a B-20. Thanks, Allen.


      Originally posted by jbird604 View Post
      I could be wrong, but I think the B20 was a ported design from the start. However, there was a sub called the HC-20 that was a sealed box. I saw someone recently listing an HC-20 on ebay or somewhere and calling it a B-20, so there is some confusion about it out there.

      The HC-20 was essentially an HC-12 without the crossover, mid, and tweeter, so it was useful for 32' stops. The only time I sold a big organ using HC-20 cabinets, we used four of them in series/parallel on a single 100 watt amp. It was in a very large church, and we got plenty of 32' tone out of those, enough to shake that building! After 25 years or so the foam rotted out and we replaced the foam woofers with rubber-surround drivers. Still sounds awesome.

      Comment


      • #4
        This depends upon how much bass you want and the room size. Are your dual B-40's about the right amount of bass for you, or are they too much or too little? If you find them about right, then you'll probably want to find the B20's. If you find them overpowering, then the HC20 might be perfect.

        Our sense of hearing in this near infra-bass region is very dependent upon the individual. What one finds perfect, another finds too strong and another finds it lacking.

        If you're looking to handle a Contra Bourdon 32', even in pipe organs, the bottom 6 notes of this stop frequently are not heard very well.

        Two B20s will only be 6 dB louder than a single B20, so the real question is if a single driver is "on the edge" of handling it well. Per the response drawing on Allen's website, the B20 is about 8 dB down from its mid-bass response when it gets down to 16 Hz. That is really extremely respectable performance for a smaller cabinet, and it's roll off is quite smooth down to 16 Hz. It's rated at 94 dB per watt sensitivity, so figure 88 dB at the low end. Assuming it can handle a full 100 Watts and remain in its linear operating range, that adds 20 dB, so figure it maxes out around 108 dB at the bottom end. A 2nd B20 makes that 114 dB, and probably not worth it in a home environment (unless you just happen to have 2 of them).

        I haven't calculated the HC-12/HC-20 bass numbers because I don't have a unit to test, but I would assume it's designed for a 32 Hz nominal bottom end, so it will be 12 dB down at 16 Hz. It is not going to be as strong on the bottom notes as the B20, but still respectable. By the way, the 12 dB down is fixed for any sealed box design at one octave below its cutoff (f3)--it's just that the f3 point (the frequency where response is down by 3 dB, which is considered the "cut-off") changes with the box volume and driver. "Cut-off" doesn't describe the shape of the curve, though, it's a smooth roll off of 12 dB per octave.

        If you're having a hard time finding a B20 and the HC20 is reasonably priced, I'd suggest getting it.

        For that matter, you could just use an HC-12; you could disconnect the crossover and just use the woofer with a direct connection--same performance as an HC-20.

        Comment


        • #5
          Toodles, thanks for the information. The room is 20x20 with an 8' ceiling; floor is polished concrete. In this setting the B40s are quite heavy in the bass, but nice, however if there is a bit less bass, that would probably be OK. I want to downsize the B-40s with something smaller that can produce enough bass so it won't feel like there is no bottom. I thought a B-20 may work. I sold Allen Organs, however the HC-20 was discontinued by the time I started selling and I know nothing about it. What do you consider a reasonable price for the HC-20. Thanks, Allen



          Originally posted by toodles View Post
          This depends upon how much bass you want and the room size. Are your dual B-40's about the right amount of bass for you, or are they too much or too little? If you find them about right, then you'll probably want to find the B20's. If you find them overpowering, then the HC20 might be perfect.

          Our sense of hearing in this near infra-bass region is very dependent upon the individual. What one finds perfect, another finds too strong and another finds it lacking.

          If you're looking to handle a Contra Bourdon 32', even in pipe organs, the bottom 6 notes of this stop frequently are not heard very well.

          Two B20s will only be 6 dB louder than a single B20, so the real question is if a single driver is "on the edge" of handling it well. Per the response drawing on Allen's website, the B20 is about 8 dB down from its mid-bass response when it gets down to 16 Hz. That is really extremely respectable performance for a smaller cabinet, and it's roll off is quite smooth down to 16 Hz. It's rated at 94 dB per watt sensitivity, so figure 88 dB at the low end. Assuming it can handle a full 100 Watts and remain in its linear operating range, that adds 20 dB, so figure it maxes out around 108 dB at the bottom end. A 2nd B20 makes that 114 dB, and probably not worth it in a home environment (unless you just happen to have 2 of them).

          I haven't calculated the HC-12/HC-20 bass numbers because I don't have a unit to test, but I would assume it's designed for a 32 Hz nominal bottom end, so it will be 12 dB down at 16 Hz. It is not going to be as strong on the bottom notes as the B20, but still respectable. By the way, the 12 dB down is fixed for any sealed box design at one octave below its cutoff (f3)--it's just that the f3 point (the frequency where response is down by 3 dB, which is considered the "cut-off") changes with the box volume and driver. "Cut-off" doesn't describe the shape of the curve, though, it's a smooth roll off of 12 dB per octave.

          If you're having a hard time finding a B20 and the HC20 is reasonably priced, I'd suggest getting it.

          For that matter, you could just use an HC-12; you could disconnect the crossover and just use the woofer with a direct connection--same performance as an HC-20.

          Comment


          • #6
            Each style of bass cabinet will "resonate" differently to said given room. The HC 20's may...or may not sound better then the B40's. I had a pair of B40's in my house and swore I couldn't hear nor feel the bass as I thought I should. However, my wife said it was shaking her bones 2 rooms over in the kitchen. Also keep in mind what you consider bass is.....ultra low end rumble, mid bass boominess...etc, etc. You may very well find that the HC 20s or B 20's might be better in the ultra low end where as the B40's might be boomier and lacking ultra low end in said given room. To me its always a test and trial situation.

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            • #7
              I moved to a new house last October. I built a music room with a polished concrete floor for the organ. In the old house with a similar size room with laminate floors, the base was just right with the 2, B40s. In the new house, the B40s on the concrete floor lack the low end rumble but have plenty of mid bass boominess as you describe. I was hoping to retire the B40s because they require so much space. Thanks for your help; it appears experimenting will be necessary. Allen


              Originally posted by Hamman View Post
              Each style of bass cabinet will "resonate" differently to said given room. The HC 20's may...or may not sound better then the B40's. I had a pair of B40's in my house and swore I couldn't hear nor feel the bass as I thought I should. However, my wife said it was shaking her bones 2 rooms over in the kitchen. Also keep in mind what you consider bass is.....ultra low end rumble, mid bass boominess...etc, etc. You may very well find that the HC 20s or B 20's might be better in the ultra low end where as the B40's might be boomier and lacking ultra low end in said given room. To me its always a test and trial situation.

              Comment


              • #8
                The 20 ft dimensions will support a standing wave at about 27 Hz, and multiples thereof; the 8 ft ceiling will support a standing wave at about 70 Hz, and multiples thereof.

                It's unfortunate that two of your room dimensions as the same, but what is, is. With a standing wave, you'll get no sound at the source and the opposite wall, and full sound in the middle of the room. Moving the bass cabinet to different positions in the room will help alleviate the standing waves, and trial and error is necessary.

                There are HC-12's on ebay now for $60, which is a great price. Located in South Carolina: http://www.--------/itm/Allen-Organ-...MAAOSwMtxXvHPk

                Comment


                • #9
                  Originally posted by toodles View Post
                  The 20 ft dimensions will support a standing wave at about 27 Hz, and multiples thereof; the 8 ft ceiling will support a standing wave at about 70 Hz, and multiples thereof.

                  It's unfortunate that two of your room dimensions as the same, but what is, is. With a standing wave, you'll get no sound at the source and the opposite wall, and full sound in the middle of the room. Moving the bass cabinet to different positions in the room will help alleviate the standing waves, and trial and error is necessary.
                  I'm sure I don't need to tell either of you this, but in rooms of that configuration (20'2), it would make sense to place the bass speakers either in the corner, or reflecting off a wall. By doing so, the square dimensions of the room are broken up somewhat (assuming reflection), and the sound can blend before being heard. If the HC20 is projecting on the diagonal (not that the bass is very directional), then the actual length of the hypotenuse is 28.284' (assuming a right angle in the corner). That dimension would almost eliminate the possibility of a standing wave.

                  I hope this gives another way of looking at the bass response.

                  Michael

                  P.S. If you do retire the B40s, I may be interested:-)
                  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


                  • #10
                    I might have a couple of b20's in good working order if you are searching. I will check in the morning.
                    Bryan
                    =÷=÷=÷=÷=÷=÷=÷=÷=÷=÷=÷=÷=÷=÷=÷=÷=
                    Magnus Europa, 4 manuals, 112 stops - church sanctuary
                    Hauptwerk 3 manual, converted from Rodgers 330 - home
                    Rodgers Allegiant 677- church chapel

                    Comment


                    • #11
                      I've found the output of the HC-20 to be quite adequate for a 32' Contre Bourdon in several installations. I mentioned an installation that I did using HC-20's for the subs. That was in 1985, just as Allen was about to discontinue the HC-20. They wanted us to get B-40's instead, but the job had already been designed to use HC-20 boxes, and B-40's wouldn't fit in the space in the chamber. So they did sell us the four HC-20's that we asked for.

                      Putting the four HC-20's in a series/parallel configuration on a single 100 watt amp produced a spectacular amount of genuine fundamental on the 32' stops. It was an ADC6000 organ (7 discrete channels plus the subwoofer channel) and it fills a 1000 seat church with awesome room-shaking tone, including bass that is to die for. The building has a very high ceiling and many hard surfaces, so it's a good place to make some good organ tone and some good bass.

                      OTOH, I service now and then an old MOS organ that a dealer installed in a 600 seat church using a single HC-20 for the sub channel. To be honest, you can hardly even tell that it's there. The bass from the standard flute/pedal cabinet (one of those 32A/B sets) is just about as good, far as I can tell. But then it was obviously a joke to add on a single 15" sub in a church that size and expect it to make a huge difference.

                      In a home music room, I'd think that a single HC-20 would work pretty well though. I'm curious to know what model the organ is. Are you currently using two B-40's in parallel on a single amp?

                      A 15" woofer in a properly-designed ported box can certainly put out a lot of bass. At church on the MDS-45 I have a Rodgers (!!) SW7.5 as the sub on the channel with the 32' Contre Bourdon. It's a single 15" woofer (and I replaced the foam woofer with an old paper woofer out of a MOS Allen !!) and has a ducted port. It seriously shakes the building. I can't hear the fundamental tone below the lowest E or F, but the walls shake, so it must be putting out a good deal of fundamental even down around 20 Hz or so.

                      But then, I once constructed custom subs for a Rodgers re-do, and the subs needed to fit into a shallow enclosure. I made boxes 2' x 4' and only 1' deep (approx 8 cubic feet) out of heavy plywood with stiffeners. I mounted a single 15" rubber-surround woofer in each one, and those little babies will shake that church too, seats about 400. So you just never know how speakers are going to work out until you try them!
                      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


                      • #12
                        Originally posted by jbird604 View Post

                        In a home music room, I'd think that a single HC-20 would work pretty well though. I'm curious to know what model the organ is. Are you currently using two B-40's in parallel on a single amp?
                        When I moved to the new house last fall, I did not move the Moller Artiste pipe organ augmented with Artisan digital ranks. The 3M Allen TC-6 console still has Allen audio -- 8 channels, 800 watts with 6 HC-15s and 2 B-40s and Artisan uMIDI. Digital ranks are now Hauptwerk E.M. Skinner sampleset. My goal is to replace the Allen B-40s with a different Allen subwoofer(s) that is smaller. When I determine the new speaker configuration, I plan to have an enclosure constructed to complement the console design to hide the speakers. The present setup has a 100 watt amp for each B-40.

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                        • #13
                          Not meaning to question your decision, but rather just interested. Is there simply not enough space in your new music room for both subs? Does downsizing to one B40 still consume too much space?

                          I'm simply curious. I moved my organ into my music room and struggled with how to use the space, wondering if I wanted to even use my subwoofer since the full range speakers can do 16' stops (my 32' stops leave something to be desired...), but after leaving out the sub I missed the smooth deep end of the subwoofer so I put it behind the curve of the piano. I can barely see it and I have my bass :)
                          Viscount C400 3-manual
                          8 channels + 2 reverb channels (w/ Lexicon MX200)
                          Klipsch RSX-3 speakers and Klipsch Ultra 5.1 subwoofers

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                          • #14
                            Originally posted by myorgan View Post
                            ... place the bass speakers either in the corner...
                            Worst location for the bass speakers is probably the corner, in this case, as it reinforces the standing wave on 2 walls. Corner placement reinforces bass, for certain, but not always in a beneficial way.

                            Put the bass cabinet on a dolly and move it around to try different spots before making a final decision. Things like furniture can provide reflection and/or absorption that can't really be planned.

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                            • #15
                              Originally posted by rjsilva View Post
                              Not meaning to question your decision, but rather just interested. Is there simply not enough space in your new music room for both subs? Does downsizing to one B40 still consume too much space?

                              I'm simply curious. I moved my organ into my music room and struggled with how to use the space, wondering if I wanted to even use my subwoofer since the full range speakers can do 16' stops (my 32' stops leave something to be desired...), but after leaving out the sub I missed the smooth deep end of the subwoofer so I put it behind the curve of the piano. I can barely see it and I have my bass :)
                              There is plenty of space for the console and audio in the room. It's set up now. Since Allen has replaced the B-40s with B-20s (still a current product) I wanted to make the installation a bit more compact. B-20s are about the size of the HC-15s. I have also found that the Hauptwerk samples are very realistic and with registration less is more. I'm thinking the more compact B-20s may produce the bass I want. The previous digital ranks didn't have the realism like Hauptwerk; the Moller pipe organ helped mask the deficiency.
                              Last edited by Moller Artiste; 09-15-2016, 12:38 PM.

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