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Thread: Opinions on the Dobro Ampliphonic Mandolin

  1. #1

    Default Opinions on the Dobro Ampliphonic Mandolin

    Hi there! A local music shop has a 1981 Dobro Ampliphonic mandolin that looks to be in pretty good shape. Iíve been wanting to get a resonator mandolin for a while, and the options are pretty limited. Are the reissued Dobro mandolins a good buy or should I keep saving for the National RM-1? Also, what issues/problems should I look for in these Dobro instruments?

    Thanks for any help/opinions you may have!

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  3. #2

    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Hi, I bought one in the UK last year. I had the neck reset as the strings are very close to the cover plate, which looks like a design fault, I believe the 30's ones are the same.

    Resetting the neck was easy though as it's held on by 2 screws through the fretboard and a stubby neckstick held on by a screw in the body.

    The strings are still close to the cover plate but it's better. The sound is good, not as percussive as the National, which I also have, but more sweet and sustainy. Same with the corresponding guitars I think, Dobro vs National.

    Mine was reasonably priced and in very nice condition. ($450) I think that was a bargain, probably the first I've ever had ! Does yours look like this one ?

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  5. #3
    Mando accumulator allenhopkins's Avatar
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    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    "Spider" bridge/cone instruments, like the Dobro, and "biscuit" bridge/cone instruments, like the National, are similar but distinct entities. There is a quite obvious difference in sound quality, between the concave resonator cone that's vibrated by means of a cast-metal "spider" framework to which the bridge is attached, and the convex resonator cone that's vibrated by a wooden disk that's directly glued to the cone, with the bridge attached to the disk.

    I own a '30's Dobro mandolin, and a steel-body National Triolian of about the same vintage, and they sound quite different. There are other differences in construction: the Dobro is wood-bodied and short-scale, the National steel-bodied with a longer (almost mandola) scale. The Dobro is sweet-sounding, with a long "ring-y" sustain, and less volume; the National is louder, with an aggressive "bark." (It also weighs about twice as much, but that's a separate issue.)

    So, whether to get a Dobro or a National, depends to a significant extent, on what kind of sound you're looking for. I would say that a Dobro mandolin in good shape for $450 is a very good deal price-wise. Neither the older nor the newer Dobro instruments were masterpieces of construction, and I had to have the neck re-set on my pre-war Dobro mandolin, for which I paid about $250 maybe 30 years ago. As you say, choices are limited, and you may not get the chance to compare two resonator mandolins side-by-side. I'd be relatively confident, though, that you could get $450 for the Dobro if you decided later to get a National instead.

    I also know that the new National RM-1 has a wood body, and a more standard mandolin scale length, so it may not be as "snarly" as my old Triolian. Cafe members who own RM-1's say that they are about the loudest mandolins they've played, so the aggressive nature of the "biscuit" National resonator construction continues in the RM-1's apparently.
    Allen Hopkins
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  7. #4

    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Thanks for the info, guys! The mandolin at the shop has the same cover plate motif, but is a sunburst finish with the two screened soundholes versus the f holes. I noticed that the few clips I found online of this type mandolin had a lot of pick noise from hitting the cover plate. I didnít notice that when I played it, but I didnít play it very long. It did have a nice, bell-like sound, that wasnít as metallic as I thought it would be.

    Regarding the RM-1, is itís volume too loud for just casual playing inside the house? My wife letís me play a mandolin-banjo, so sheís pretty patient, but I would just as soon not see the inside of the dog house.

    Thanks again!

  8. #5
    Mando-Accumulator Jim Garber's Avatar
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    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    I had a '29 Silver National mandolin and it was a beautiful instrument but I hated the sound when tuned to a std mandolin. The problem was the longer scale, I believe close to 15". I did have it strung for some time to lower tuning (blues in E) but still really rarely played it. I don't know about a 1980s Dobro mandolin.

    However, when I acquired my RM-1 I sold my vintage National and did not look back. I am a vintage guy for the most part but the RM-1 has mandolin tone. Yes it is pretty loud but also sweet. I would not play it after your wife goes to bed. However, compared to a mandolin-banjo I think the RM-1 is a much superior and pleasing instrument.

    Having said all that, just bear in mind that a vintage one is a completely different beast and mught be appropriate for a more funky sound.
    Jim

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  10. #6

    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Thanks! I really love the tone of the RM1 from the clips Iíve heard. Donít know why theyíre not more popular than they are.

    The Dobro mandolin is priced ~$900, which is around the price Iíve seen them listed online. I keep thinking Iíll find the holy grail mandolin that will finally cure me of MAS.

  11. #7

    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    I put silk and steel strings on my RM1 and it adds a mellow edge to the sound, I also play with a 0.60 light pick. It's a longer scale but easy to play and the fretboard is fairly wide. I've tried various sets of strings on it and they all sounded good in fact. The Dobro gets EJ73 strings, medium light, and sounds great. I tend to use it for chords & accompaniment when I sing. It's smaller than taking a guitar to pub sessions and is also good for knocking out a few jigs and reels. $900 sounds okay to me but bear in mind the neck reset, you might want to do it later. Mine cost $120, there's not much work involved.

  12. #8
    Mando-Accumulator Jim Garber's Avatar
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    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Unless the have changed the specs on the RM-1, I believe they are only 1/8” longer in scale length than standard mandolins—14”. The neck is a little wider at 1-1/4”.
    Jim

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  13. #9

    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Hi Jim yes you're right. I had 15 inches in my head but it measures at 14 exactly.

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    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Very happy RM-1 owner here. It can be loud, but itís also the most dynamic mandolin I own, so you can most definitely play softly on it. Just requires some right hand control, or, if I really need to be quiet, iíll use a Dawg shaped pick, out of which I canít seem to pull any volume or tone. Tone ranges from mandolinny with a little reso edge to searing reso with a slide. I really, really like it.

    The string break angle on these is set pretty shallow to reduce excessive pressure on the biscuit/cone, and I had some trouble with one of my A string popping out of its saddle slot when I played it aggressively. Had a luthier deepen the slot ever so slightly, and have had no issues since. Just offer in the spirit of full disclosure.
    Chuck

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    Mando-Accumulator Jim Garber's Avatar
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    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    I had the same problem and I just deepened the slot in the bridge a bit. My only complaint is that they are a royal pain to change strings with that beautiful but somewhat impractical tailpiece.
    Jim

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  17. #12

    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Decisions, decisions. In a perfect world, Iíd just get both. Resonator instruments are just plain neat!

    Speaking of luthier work, is it hard to find luthiers that are comfortable working on these instruments?

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    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Quote Originally Posted by Jim Garber View Post
    I had the same problem and I just deepened the slot in the bridge a bit. My only complaint is that they are a royal pain to change strings with that beautiful but somewhat impractical tailpiece.
    Agree the tailpiece makes string changes a pain, but I tend to change them less on that mandolin since it’s not my primary player. Would be way more annoying if I were performing several times a week with it, though...

    Not sure about how difficult it is to find someone to work on them. I’m blessed to have a couple of local guys who know their stuff, and Lowe Vintage and Skip Kelley are both about an hour and a half away from me. Had I done my research I could have fixed the bridge issue myself, but I wasn’t sure if the neck angle needed to be tweaked and didn’t want to turn a small issue into a larger one...
    Chuck

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    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    I'd go with the RM-1, it can be played very quietly and sweet or as loud as you like, it's really a versatile mandolin.

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  21. #15

    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    They're very simple devices, I found some pics on the internet and took them to a good general luthier & he said he'd have a go at the neck reset.

    The cover plate comes off, the resonator assembly lifts out in one piece, remove three screws & you have the neck off. Two of them are hiding below the pearl markers at the end of the fretboard.

    However, if it plays okay when you get it, leave it alone. The only thing to adjust is the little bolt which connects the cone to the spider, and there's info how to do it on the web.

    Which one you buy is down to budget but I'd consider the Dobro while it's available as they're a bit harder to find.

  22. #16

    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    There's a beauty on Ebay USA for $1,079.

  23. #17
    Mando accumulator allenhopkins's Avatar
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    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Original Dobro mandolins are fairly cheaply made; Dobro and Regal had an arrangement where Regal provided wooden bodies, Dobro the resonators. Resonator mandolins and guitars were sold under both nameplates.

    My '30's Dobro was not at all that nicely built inside. When I needed the neck re-set, my repair guy said that the neck block was made from a very soft wood (he said "balsa wood," but I think that was hyperbole). As Davey posted, the resonator assembly is quite straightforward, not hard to work on.

    One drawback of resonator instruments, is the limited degree to which the bridge placement can be adjusted. Not like a "standard" mandolin, where bridge location is easily changed. There's a bit of "wiggle room" if the spider, or in the case of Nationals, the cone with "biscuit" bridge, can be slightly shifted toward the neck or the tailpiece, but this is normally a tiny fraction of an inch.

    Raising or lowering the action often means that bridge location needs to be slightly shifted, since the amount of string stretching involved in fretting changes, affecting intonation. Not a lot of flexibility in bridge placement on a resonator instrument.
    Allen Hopkins
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  24. #18

    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Iíve really enjoyed this thread. Thank you to everyone for sharing your knowledge with me. Iím really glad I joined this forum!

    I want to say the Dobro reissues come with an adjustable truss rod. Wouldnít you be able to adjust the string height with that?

  25. #19
    Mando accumulator allenhopkins's Avatar
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    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Quote Originally Posted by Ragtimer77 View Post
    ...I want to say the Dobro reissues come with an adjustable truss rod. Wouldn’t you be able to adjust the string height with that?
    You can adjust the straightness or "relief" curvature of the neck with an adjustable truss rod. This will affect the string height to some extent.

    Changes in string height can also make it necessary to adjust the bridge location -- the scale length, from nut to bridge -- to compensate. Strings higher off the fret board stretch more when you press them down to the neck, which tends to raise or "sharp" their pitches. When you lower the action, this effect is reduced, so that a string that intonated accurately with a higher action, may sound lower or flat with a lower action (this applies to fretted strings only). On a standard mandolin, the bridge may need to be moved a fraction closer to the neck to restore proper intonation.

    On a resonator mandolin, the bridge is pretty much fixed in place, not movable to allow for changes in string height. Is this a major problem? Likely not, since unless the change in string height is significant, the change in intonation will normally be fairly slight. But a sensitive tuner (or sensitive pair of ears) may detect a change in intonation that cannot be corrected by the very minuscule changes possible with a fixed-bridge resonator instrument -- sliding the cone or bridge assembly as much as construction permits, altering the bridge saddle to compensate.

    Worth putting up with, IMHO, to get the distinctive tone of a resonator mandolin. But still a factor.
    Allen Hopkins
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    Mando-afflicted lflngpicker's Avatar
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    Default Re: Opinions on the Dobro Ampliphonic Mandolin

    Just wanted to add, Don Young, the founder of the 2nd iteration of National Reso-phonic Guitars, designed the RM-1 and developed those mandolins. He also was plant supervisor as a young man in his 20's at the Long Beach Dobro shop in the late 70's and into the 80's and knew those instruments inside out. His first experience with a resonator was taking apart and putting back together a Dobro guitar and then he was hired there, working his way up to the position of plant supervisor. He brought the knowledge from Dobro to his restoration of the National brand in San Luis Obispo with his friend McGreagor Gains in 1989. I am not a resonator expert-- just a player of wood body nationals-- guitar and mandolin. Also, Don and I were close friends and he is my first cousin on my Dad's side. His builds are incredible! We miss him so, so, so very much. What a man of compassion and humility, but brilliant.

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