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Hammond Magnatone Connection

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    Hammond Magnatone Connection

    I've recently been working on a Magnatone M15A amp, and I've been learning more about the Magnatone amps, partly because this one was such a basket case. I had to pay particular attention to the reverb because this one had a dead tank on arrival.

    Magnatone's first version of the M15 in 1963 had a dedicated reverb channel with a transistor recovery stage followed by two 6GW8 tubes. Sound familiar? While not an exact copy of the AO44, it's definitely a close adaptation of that circuit. The 6GW8s drove an 8" reverb speaker used only for reverb. Magnatone ran the 6GW8 output sections in fixed bias rather than cathode bias.

    Later versions of the M15 dropped this third output channel and third speaker. I wonder if this was to reduce complexity or if Hammond had some issue with the borrowing of the AO44. I suspect the former.

    It's always interesting to me to see how the early adopters of spring reverb for guitar amps took their cues from Hammond's designs.
    I'm David. 'Dave' is someone else's name.

    #2
    The modern equivalent is the Supro which National also marketed for years. Magnatone was part of that 'family'.
    Don't know that it uses 6GW8 tubes,sure has a decent 'verb though.
    Guitar 'amp mod' people seem to prefer kidnapping the AO35 though,and thankfully leave the AO44's alone!
    These AO44's seem to return more treble than AO35,maybe that's just mine.
    Guitar through the rca on both to test confirms my theory.
    "Hey this amp has an octal rectifier etc' so it's just GOT to sound better". Not.
    Thank you Hammond for making the AO44 look so dorky,and sound so great.
    Can't blame a guitar amp builder for trying to copy an excellent sounding circuit.
    sigpic A100/251 A100/147 A102/222 B2/147 BCV/122 M3/145 M102/145
    Various modern keyboards and modules.

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      #3
      Maybe I'm misunderstanding, but I'm pretty familiar with Valco and the associated National and Supro brands, as well as Oahu, Wards Airline and Gretsch. Magnatone was a completely separate company, at times associated with Estey Organ, with pretty unique designs, such as their varistor-based vibrato circuit. Valco never built anything like that, as far as I know.

      The Magnatone reverb circuit adapted from the AO44 is used as a reverb recovery circuit only, just as it's used in organs. It's not used as the main guitar output channel.
      I'm David. 'Dave' is someone else's name.

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        #4
        Thanks for the amp geneology David.I assumed that National was the parent company,Magnatone,Standell,National imported into Canada by WC Kaye.
        Here in Canada there weren't many amplifier distributors when those were new in the early 60's.
        Yes,that transistor driver does the job in the AO44! Regardless of the 6GW8 circuit intended uses,they are becoming rare.
        The rectifier isn't the only tube plucked from my dormant AO44 here at home.
        Yes I have two pairs of 6GW8 tucked away.And a few 12BH7 OEM too.
        Tartini Music,was based here in New Westminster,and was the sole national distributor for Fender exclusively in Canada for many years; back as far as '53.
        The building still stands.Bully's Rehearsal Studios on 6th St. in New Westminster.
        Three other main players who are still around in one form or another distributed the rest of the name brands in Canada.
        Guitar store amps in Canada 50 years ago came in four varieties,Fender,Traynor,Garnet,pawnshop.
        Others were available but those three were the marquee brands and eventual 'resellers'.

        Gretsch,Baldwin,Magnatone,National,Standell; all sold at Ward Music up here.
        Traynor,Shure,Ludwig,Rickenbacker were at one place(JMJ),Vox,Gibson,Garnet,Rhodes were at another(Harmony Kids).
        Quite a few keyboardists were Jerome's customers.They sold Hammond,Farfisa,RMI,Rhodes,Hohner.
        I saw and heard the first Marshall 'stacks' in Canada at Star Exchange Pawnbrokers in Edmonton 1967,AKA WC Kaye Imports.
        Teisco,Raven,Ekosonic,Zen-On,all brought to Canada by WC Kaye Imports.


        Supros here were all special order imports,never franchised .Danelectro guitars and basses were 'on the floor'.
        National sold big,a lot of lap steels and amplifiers.Valco and Supro were imported by special order only.

        The harp player I work with in the Mud Bay Blues Band(Mud Bay Slim) uses an original '6V6' powered National amp and has a '6V6' Valco amp for a spare.
        Great stuff when it's up to spec.Screamin' 5 watts!
        Harpdog Brown was using a custom built National circuit someone in the USA built for him last time we played together.Honest 5 watts for sure!
        At least five orphaned brand stencil amps were made up here that are highly sought after by garage band guys. 10W RMS!
        Mostly Garnet built stencils with names like Paul and Raven and Eaton's 'Viking'.
        Jerry Doucette,Robbie Robertson,Randy Bachman; all played through stencil amps as kids.So did Neil Young.
        A properly setup Fender Deluxe Reverb will almost get that tone,not quite though.Too hi-tech a circuit I guess?
        sigpic A100/251 A100/147 A102/222 B2/147 BCV/122 M3/145 M102/145
        Various modern keyboards and modules.

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          #5
          In the National, Supro, etc.. family, Valco was the brains of circuit design and amp building.


          Garnet is an interesting case because it's one of the few amp brands actually based in Canada. Canadian techs get them frequently, but I've never seen one here in the lower 48.
          I'm David. 'Dave' is someone else's name.

          Comment


            #6
            Hammond owned Accutronics and it's likely that Hammond's design was published as the reference design and freely used by others.
            -Admin

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