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tapering -- before/after comparison .. sound records?

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  • tapering -- before/after comparison .. sound records?

    Hi,
    as I am thinking of adding foldback to my M100, I also checked tapering.

    Unfortunately, I could not find any sound examples or vidoes that compare before and after tapering.

    All I find is foldback plus tapering sounds afterwards, but then it is hard to decide on tapering itself.
    Does someone have any links or records?

    Cheers, Mark

  • #2
    Hi Mark.


    I've also searched for clean audio recordings of the Hammond sounds with no result. Everything I've done so far with my Hammond emulator programmed in a STM32F746 evaluation board with touchscreen are stabs in the dark but I've read up on so many details that I could find. The hardest part was to evaluate the scanner vibrato sounds since I was stubborn enough to actually build my own scanner vibrato unit. What I could offer you in this context are some samples from my emulator which can switch between manual tapering as well as tonewheel volume calibration should be enabled or not.

    This first comparison evaluates the effect of tapering when the tonewheel volume calibration curve is enabled.

    https://instaud.io/2Hhu

    Another possibly less intresting clip is the one where no calibration curve is enabled

    https://instaud.io/2Hhz

    The sound is similar but one important this I've noticed is that the calibration curve seems to diminish the effect of the tapering and they work against each other. This means that the fullest sound is obtained when tapering is enabled but no calibration curve and the thinnest when the opposite applied that is calibration curve enabled but without tapering.

    As you can hear the effect of tapering in particular is most significant for the higher notes and at best subtle for lower and midrange notes. These recordings were made with full drawbar registration. I'm rather satisfied with this emulator so far and I think it would sound pretty fat through a Leslie cabinet.

    I share your frustration that no audio database has a bank of reference material to listen to and even perform analysis to. A YouTube recording through air taken with a cellphone is far from good enough in this context. The only useful thing would be a direct recording from the Hammond preamp.

    Hope this is of any help.


    Cheers

    Tobbe

    Comment


    • #3
      Thanks, Tobbe.
      In your examples it is switching from off to or without/with each time?

      Interesting project! Sounds too time consuming for me...

      Cheers, Mark

      Comment


      • #4
        Originally posted by markimark View Post
        Thanks, Tobbe.
        In your examples it is switching from off to or without/with each time?

        Interesting project! Sounds too time consuming for me...

        Cheers, Mark
        I only switch tapering off and on in each audio clip. At first it is turned off and then switched on when the chord is repeated. For higher pitched chords the effect of the tapering is at its strongest. In my opinion the effect of tapering is really an advantage to the sound.

        Comment


        • #5
          I am planning on tapering my M-100 for a project this winter. I will make some before/after recordings then if you're still interested. Since the organ already has full foldback, you'll get to hear that mod before and after tapering. I've done the tapering to both my M-3 and L-100 and the difference in the top octave is very noticeable.
          Farfisa Mini Compact V1, Fender Rhodes 73 Mk. 1, Hammond B2, Hammond L-102 "El Choppo", Hammond M-101, Hohner Cembalet CF, Hohner Cembalet N, Hohner Favor Combo, Hohner Pianet L, Hohner Pianet T, Hohner Symphonic 30N, Leslie 145, Leslie "430" (former 130 cab with horns and light show added), Nord Electro 3, and an entire village of guitars and harmonicas.

          Comment


          • #6
            In a console, Tapering is accomplished by a combination of two factors, as I understand it.
            1) the distance (gap) between pickup coil and rotating wheel. This is difficult to set correctly, but can be done.
            2) The impedance (length) of the resistance wire. Any give note might be represented at various levels this way.

            On a spinet, there is no impedance tapering. The resistance wires are all the same value (16ohm?). Further, once you add foldback, you're in uncharted territory. There is no right or wrong way to do it, at least according to the factory, because the factory never did it. You can emulate the upper manual of a console but the lower manual of a spinet is setup with different tones and harmonics, so adding foldback there is still kinda uncharted.


            I added foldback and find that ordinary Hi/Mid/Lo external tone controls are amazingly useful if i wanna dial in a sound.

            Comment


            • #7
              Originally posted by tiredoldgeezer View Post
              On a spinet, there is no impedance tapering. The resistance wires are all the same value (16ohm?). Further, once you add foldback, you're in uncharted territory. There is no right or wrong way to do it, at least according to the factory, because the factory never did it. You can emulate the upper manual of a console but the lower manual of a spinet is setup with different tones and harmonics, so adding foldback there is still kinda uncharted.
              I wouldn't call it "uncharted territory". Full foldback with no tapering (all manual resistance wires at the same resistance) is exactly how the older consoles - "pre -V" organs - are wired.
              Current organs: AV, M-3, A-100
              Current Leslies: 22H, 122, 770

              Comment


              • #8
                Originally posted by tiredoldgeezer View Post
                In a console, Tapering is accomplished by a combination of two factors, as I understand it.
                1) the distance (gap) between pickup coil and rotating wheel. This is difficult to set correctly, but can be done.
                2) The impedance (length) of the resistance wire. Any give note might be represented at various levels this way.

                On a spinet, there is no impedance tapering. The resistance wires are all the same value (16ohm?). Further, once you add foldback, you're in uncharted territory. There is no right or wrong way to do it, at least according to the factory, because the factory never did it. You can emulate the upper manual of a console but the lower manual of a spinet is setup with different tones and harmonics, so adding foldback there is still kinda uncharted.


                I added foldback and find that ordinary Hi/Mid/Lo external tone controls are amazingly useful if i wanna dial in a sound.
                I believe the distance between tonewheel and pickup determines the volume output from that pickup. For some reason this is not intended to be flat which is particularly strange since the sonic performance it yields is rather opposite of that compared to tapering and these two work slightly against each other. The volume calibration curve tends to emphasize higher frequency pitches and tapering does the opposite. With that said the overall sound still sounds better with the volume calibration and tapering together as opposed to a flat tonewheel generator with no tapering. I've read somewhere that someone thought that the volume calibration curve was intended to compensate for the matching transformer impedance but I have no idea. I've also read that tapering was intended to suppress keyclick from the contact switches. There are many questionmarks here apparently.

                The volume calibraton article is here

                http://www.dairiki.org/HammondWiki/T...orOutputLevels

                and for tapering

                http://www.dairiki.org/HammondWiki/ManualTapering

                Unfortunately there is no graph in the calibration article but I've drawn that in SciLab and it looks like a truncated sine wave that goes down on the lower half of pitches and up on the higher half of pitches. Since my project is in software it is extremely convenient to have switches for both the volume curve as well as tapering. This is the basis for my conclutions regarding this. But I might have overlooked one or more details when it comes to the real thing.


                Cheers

                Tobbe

                Comment


                • #9
                  Originally posted by misterstarshine.tobbe View Post
                  I've read somewhere that someone thought that the volume calibration curve was intended to compensate for the matching transformer impedance but I have no idea. I've also read that tapering was intended to suppress keyclick from the contact switches. There are many questionmarks here apparently.
                  It's also important to note that early consoles (A and such) did not use the same expression pedal as everything since. The rotary plates (adjustable capacitor, really) is not the same as a volume control (which was done at the draws). As the expression pedal moved, the freq response also changed -- hence "expression" and not 'volume'.

                  Early consoles used a series of leaf switches and simple resistors, essentially making the expression pedal a 20 step (or so) volume control.

                  Lots of possibilities, depending on the sound you want. Heck, even new Hammond (and Korg) owners take the time to tweak individual 'tonewheels' in their software.

                  Comment


                  • #10
                    Originally posted by misterstarshine.tobbe View Post
                    I believe the distance between tonewheel and pickup determines the volume output from that pickup. For some reason this is not intended to be flat which is particularly strange since the sonic performance it yields is rather opposite of that compared to tapering and these two work slightly against each other. The volume calibration curve tends to emphasize higher frequency pitches and tapering does the opposite. With that said the overall sound still sounds better with the volume calibration and tapering together as opposed to a flat tonewheel generator with no tapering. I've read somewhere that someone thought that the volume calibration curve was intended to compensate for the matching transformer impedance but I have no idea. I've also read that tapering was intended to suppress keyclick from the contact switches. There are many questionmarks here apparently.
                    One thing to keep in mind is that TWG volume calibration affects all notes that use a particular tone, whereas tapering can affect the same tone differently for different keys using that tone.

                    For example, consider tone #37, which is the fundamental (8') tone for middle C. It is tapered as follows:

                    16' (C above middle C) : 15 Ohms (+3.5dB)
                    5 1/3' (F below middle C) : 24 Ohms (0dB)
                    8' (middle C) : 24 Ohms (0dB)
                    4' (C below middle C) : 34 Ohms (-3.5dB)
                    2 2/3' (F 1.5 octave below middle C) : 10 Ohms (+7dB)
                    2' (C two octaves below middle C) : 10 Ohms (+7dB)

                    I have no idea how the tapering values were arrived at, i.e. how did someone decide that this "sounded good"? Perhaps the intent was to model the changing harmonic structure of a set of organ pipes. For example, a given class of pipe does not have the same harmonic structure across the entire keyboard, but for a given drawbar setting, a non-tapered Hammond with a flat volume curve and flat amp response would have the same harmonic structure across the entire keyboard.

                    BTW, my understanding is that the volume calibration curve, together with the opposing frequency response curve of the amplifier, is intended to reduce keyclick.
                    Stefan Vorkoetter: http://www.stefanv.com

                    1962 Hammond M-111 with Improved Vibrato, Internal Rotary Speaker, Drum Machine,
                    Window Seat Tone Cabinets, Completely Rebuilt Amplifier, and Recapped Tone Generator.
                    1978 PAiA 1550 Stringz'n'Thingz with many enhancements.
                    2017 Raspberry Pi organ-top synthesizer.

                    Comment


                    • #11
                      Originally posted by stefanv View Post
                      I have no idea how the tapering values were arrived at, i.e. how did someone decide that this "sounded good"? Perhaps the intent was to model the changing harmonic structure of a set of organ pipes. For example, a given class of pipe does not have the same harmonic structure across the entire keyboard, but for a given drawbar setting, a non-tapered Hammond with a flat volume curve and flat amp response would have the same harmonic structure across the entire keyboard.
                      As everything about a Hammond was about emulating pipes, I'm certain you'd be correct with "sounded good", as that's the way pipe builders have voiced organs for centuries.

                      As the OP was concerned about a spinet, the entire tapering question changes from console practices, I think. The lower manual of a spinet doesn't exist on a console. The upper manual, after adding a bunch of tones, can more closely represent a console. And maybe that's the salient question: is this about imitating a console or just about getting something that sounds good?

                      Because with the M series, you won't ever totally get there without some serious DNA work. But about anywhere along the way, it'll still sound good.

                      The spinets were made for a decidedly different market.

                      But, I still agree, it was about what "sounded good" to them, too.

                      Comment


                      • #12
                        Hi,
                        I really appreciate the discussion my post started! Very nice.Thanks.

                        @theseacowexists : I am still interested in such recordings.

                        My intention first was to just add full foldback.
                        Having the manual (upper) open, I thought of tapering mainly because the manual would be open anyway. As I have no clue what difference in sound it would make, I started this topic.
                        I don't want to 100% copy a B3, I am more interested of good / better sound.
                        As good is relative, I would like to hear before I do it.

                        Another idea is to taper and fold back the upper and add more contacts to the lower to have a backup of the original upper.

                        Comment


                        • #13
                          Originally posted by markimark View Post
                          My intention first was to just add full foldback.
                          Having the manual (upper) open, I thought of tapering mainly because the manual would be open anyway. As I have no clue what difference in sound it would make, I started this topic.
                          I don't want to 100% copy a B3, I am more interested of good / better sound.
                          As good is relative, I would like to hear before I do it.

                          Another idea is to taper and fold back the upper and add more contacts to the lower to have a backup of the original upper.
                          Hmm....
                          Upper: Add a bunch of contacts. In the M2/3 you get 18 more for "free" as they're just grounded and you need merely distribute them properly. If you haven't already, go to YouTube and look up "poor man's foldback" to get a pretty good idea where this is headed.

                          But to complete the picture you need another couple dozen contacts and at least 3 full length replacement bus bars. This requires at least one donor organ. Remove the keepers and some contacts; R&R some bus bars; install a bunch of new contacts; replace the keepers; distribute the new tones.

                          Geoff Dariki (that I nominate for Sainthood) and his Hammond Wiki is your friend in this detailed research.

                          Lower: Repeat all of the same. However, there is no such thing as 'backup of the original upper'. Well, wait. I suppose it's possible, but you're talking much work. Count your drawbars. You'll notice you're missing one. Examine your footage. You'll notice you have a stranger (4 1/3?) present. So to change all that to become console style lower is molecular level surgery. Can be done, of course. And i find it fun. But it's not gonna get done before lunch.

                          I agree that the sound is better. Youtube is replete with demos of modded spinets. More presence overall and "scream" when needed.

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