Gibson MB-4 Trapdoor Banjo mandolin info request

So I've gotten a bug to play this MB-4 which I purchased some years ago but have never really cottoned to. I've never played an actual banjo. So I'm at sea.

Attachment 196306

The FON stamped inside the rim: 11989-10. Reverb's FON listing: 1917-1923, 11000-12000. That would put mine into 1923?

In any case, my biggest issue is with the strings. I don't care for the heavy strings on it currently (don't know what they are as they were on the instrument when I bought it). I just snapped an E as I was tuning it up. So, what is proper and/or desirable? Steel? Nylon? Suggested gauges?

I searched the Cafe archives without much success. I went to Banjohangout, but there wasn't much there and nothing about strings that I could see (maybe my searching was at fault). I went to Banjo Cafe but didn't see any forums there for asking help.

Thanks in advance for sharing your expertise.

Several times POPS1 recommended (light) tenor banjo strings to tame the beast. I bought an old no-name banjolin last winter and found it not only obnoxious but almost impossible to tune because all the other strings would shift cause they were all sitting on that soft head. I didn’t change the strings, but, being a physicist person, theorized that since there were no cavity acoustics or resonant plates involved, the miserable thing wouldn’t care at all what it was tuned to: that is, it’s just a loudspeaker cone. So I just loosened the strings till it sounded less nasty. It’s much better, but it’s a clumsy, pointy, heavy thing, good for a run every few weeks.

Not necessarily light tenor banjo strings. Just but two sets of regular CGDA tuned tenor banjo strings. Those gauges are probably just about right for an MB. I have a small-headed (7") Weymann style 25 MB with a skin head and it even sounds good with heavier strings. The only MB I ever owned. I think they can be decent instruments for a narrow range of novelty musics.

Yes, two sets of tenor banjo strings. I use a 10-28. Sounds good and doesn't put too much tension on the head and neck joint.

I had a MB-3 from the same era.

The key to these old wonders is what they have in the way of a tone ring. Most either have bare wood (no tone ring), or at most a brass tube. The later, most ornate ones had the early sprung Ball Bearing tone rings, which were reputed to have been designed by Loar himself. Some of these even had the early plastic dish resonators instead of the trap-door resonators. These were the predecessors of the 1925 and 1926 Mastertones that had Gibson's final BallBearing tone ring design, and which were a very positive big step in tone and volume production.

I eventually gave my MB-3 to a dear friend as a gift; I could never connect to it because of it's hollow, plunky tone. The trap door resonator was pretty cool though. I still have my late 1925 BallBearing MasterTone, and probably will hang onto it as my backup 5-string.

While I owned the MB-3, I learned to love those ivoroid pickguards. The new owner of the MB-3 didn't want the ivoroid pickguard that came with it, so I kept it and have used it as a finger rest for my BallBearing Mastertone. I've either purchased or made similar pickguards/finger-rests for all my main player 5-string banjos since then, including my RB-800, my SS Stewart classic banjo and my Gold Tone cello banjo. Keep those fingers off the heads and banjos can really sing (sort of like Tone Gards).

I realized a while ago that a banjo needs a lot less downward tension to drive the thin drum head than a carved or even flattish wooden one. Hence the light strings work better.

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Originally Posted by Jim Garber

I realized a while ago that a banjo needs a lot less downward tension to drive the thin drum head than a carved or even flattish wooden one. Hence the light strings work better.

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Never had opportunity to either play or study the mechanics of banjos, which seem not quite as simple as I mentioned above, but one of the things I noticed right away was that the tailpiece adjusts in height, which allows change of the string angle over the bridge, (breakover) which changes the downforce. This makes it possible to set it very low, the lowest limit would be when the drum head (mass, spring force) can’t follow the string vibrations and contact is lost. And the spring force is a function of both the head elasticity and the hoop tension.
So overnight I was kept up thinking of a testbed for looking into this. Annoyed at self this morning.

I have a 1922 Gibson MB-1 Trapdoor that I am still having trouble warming up to. I did find Pops1's advice to be very helpful and followed it. I also had to put a new head using skin on it. It looks too cool to not keep right now besides it makes good company for my 1917 A-1.

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Originally Posted by Richard500

Never had opportunity to either play or study the mechanics of banjos, which seem not quite as simple as I mentioned above, but one of the things I noticed right away was that the tailpiece adjusts in height, which allows change of the string angle over the bridge, (breakover) which changes the downforce. This makes it possible to set it very low, the lowest limit would be when the drum head (mass, spring force) can’t follow the string vibrations and contact is lost. And the spring force is a function of both the head elasticity and the hoop tension.
So overnight I was kept up thinking of a testbed for looking into this. Annoyed at self this morning.

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Interesting consideration...

As an example, for me the James tailpiece came close to this for my mandolin. On mine, just installing it as it arrived and using the same original screw holes raised the strings about 1/16th of an inch on exit of the tailpiece. reducing the breakover angle a bit.

The instructions for the James tailpiece include bending the mount angle up or down slightly to keep string contact low and against the rubber o-rings to prevent overtones and string vibration; mine didn't need bending, worked as described out of the box...

It would seem if there were a shim or some clever mechanism under the lower portion of the mount area, that adjustment could be done without bending by adjusting the mounting screws, and at the same time the breakover angle could be adjusted. Just a thought...

Related to tone, there is some charm to having a light tailpiece, even on banjos. The ever-popular Presto tailpiece on Mastertone style banjos is cast brass, pretty light and relatively solid when installed properly, and it has very little adjustability. The James tailpiece is bronze and also pretty light, but solid compared to the traditional stamped tailpiece, and interestingly also has very little adjustability when installed properly.

Modern banjo tailpieces often have a knurled threaded shaft that presses against the side of the shell, allowing the tailpiece angle to be adjusted and thus varying the pressure exerted to press the strings down into the bridge slots. Example

Joe, not sure that your "trap door" has one of these. The adjustable tailpieces are mainly made for 5-string and tenor banjos; it could be hard to find one for eight strings. The main adjustments I'd see in terms of modifying the instrument's sound are:

1. String gauges; you've gotten some sage advice above. I've had decent success with light-gauge mandolin strings on my Vega Little Wonder, which has a simple tone ring, but no resonator.

B. Head material and tightness. I have a no-name mandolin banjo that I had refitted with a Renaissance head (this one is an 11" for a regular banjo, but they do come in mandolin-banjo size -- at least mine did). I don't have the tightness "cranked," and the instrument, while still a bit raucous, is listenable.

III. While it's a bit more difficult with a trap-door type resonator, a dampening fabric (towel, Pete Seeger recommended a diaper) folded between the dowel stick and the head and located under the bridge, will dampen both volume and high overtones. Quite a few clawhammer banjoists utilize this; bluegrass banjoists, however, eschew dampening and crave excessive volume. Yes we do.

You have a sweet instrument there; don't over-listen to those who find mandolin banjos over-raucous and piercing. They are what they are, and are quite suitable for certain styles of music, where a banjoistic timbre fits in well. I used my Vega on some klezmer tunes, for example, in the band I played with for a couple years; argued well with the lead clarinet in that context. Experiment, and I betcha you'll find a niche for it.

Thanks, everyone, for your, as always, sage advice. I will go with the light tenor banjo strings per Pops1's recommendation. I can only agree with allenhopkins that there is a place for this; I expect to have lots of fun finding it.

Here is the tailpiece minus its cover ...

Attachment 196337

doesn't seem adjustable in any way.

And as for the skin, well, not being familiar with banjos, it is hard for me to say what it is, but I can say that it doesn't feel like skin/hide ... feels like plastic.

Again, everyone, thanks for your input. And sorry about Richard's loss of a good night's sleep.

Regarding the head, looks like a mylar head utilizing a painted Remo Weatherking (or similar) stretcher band (below the tension hoop). A skin head would have a thinner flesh hoop that wouldn't show on the outside.

The two hooks on either side of the tailpiece, probably allow the adjustability. You may have to put a little shim between the top of the hoop and the tailpiece, and then tighten against it, or not even. My no-name isn’t where I am today, or I’d add a photo. It’s a single adjusting screw bearing against the hindmost through-rim fixtures.
Since I’m here chattering, I’ll mention that I looked up that ‘ball bearing’ tone ring setup. The word in engineering Yiddish is “oy”!

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Originally Posted by Richard500

... I’ll mention that I looked up that ‘ball bearing’ tone ring setup. The word in engineering Yiddish is “oy”!

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While it was extremely successful and a milestone for Gibson, Gibson only made the Mastertone version of the Ballbearing tone ring for 2 years, 1925 and 1926. My understanding is that when Gibson vacated the Kalamazoo factory in 1984, there were still springs, washers and ball bearings hiding out in cracks and corners of the factory floor. :grin:

There is an even lighter set 9-13-20-32, than the light 10-15-24-36.

lighter strings reach pitch at lower tension . so won't force the bridge to be pushed down as much with a given head tension ..

a little physics balance.. :popcorn:

I Have e Vega Lil Wonder with a synthetic head rather than calfskin

I put some low density (mattress) foam between the rim stick & the head under the bridge ,
that adjusts the tone, a bit.. less ringing not so loud..

I have a ball-bearing Mastertone GB-3 banjo, converted to an RB-3. Despite the oddity of its construction, it sounds fine.

Today, I took the MB-4 to my luthier, Marc Glickman. Indeed, there were more issues than heavy strings that need attention:

-- The skin is calf, not plastic as it seemed to uninitiated me, and it needs tightening or replacement if tightening proves untenable. A plastic replacement would work but Marc said it is hard to find 9-inch plastic. I am hoping the skin is salvageable despite the need for periodic humidity-driven tightening or loosening (I keep it with my other instruments in a humidity controlled room).
-- Also, the neck needs adjustment to better the action and to keep the lower portion off the skin--this seemed to be eminently do-able.
-- And a new compensated bridge.
-- And new strings, of course.
-- And maybe a bit of silver polish to the plated rim.

Into the bargain, Marc gave me a mini banjo 101 lesson which included a warning (pace allenhopkins) about raucous and piercing; he demonstrated the use of a towel to alleviate possible complaints from the peanut gallery. Actually, while my old ears won't mind the raucous and piercing and my dogs will just leave the room without complaint, the towel was interesting because it seemed to add, depending on how one positioned it, a variety of possible tone coloring.

In any case, thanks, again, for all of the advice and education. Don't know how long repairs will take, but when it comes back to me, I'll check back in one last time to wind things up.

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Originally Posted by Joe Bartl

...Marc said it is hard to find 9-inch plastic...

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Here's Smakula's banjo head inventory page. Appears no 9-inch in stock, but willing to special-order from Remo, which he does 4-6 times annually.

Probably will cost you. If you can work with the skin head, that may be your ticket.

I had a 1923 MB-4 but in some circles I was told it was an MB-5? As everything on it was silver plated-even the Loar engraved pearl button tuners! The tailpiece cover was silver with "The Gibson" engraved on the end not on the face of the tailpiece cover-neat! Also the trap door was all Cremona burst on nice figured maple! I want to say it was 9 inch head? maybe 10 but it was smaller than all the other MB's I've seen!

Most of the trapdoor banjo's Ive seen were 10" heads. Not to say they couldn't have made some with different size heads, it is Gibson after all.

Thanks, once again, for all the info and suggestions. To put a close on this, I just want to report that I picked up the MB-4 from my luthier yesterday. The instrument is as described by William Smith (penultimate message above), with all hardware silver-plated and figured maple with Cremona burst on the trapdoor.

Now that Marc Glickman, my luthier, has finished stretching the skin, resetting the neck, making a new ebony compensated bridge, putting on GHS Ultra Light strings (9-13-20-32), and lightly dressing the frets -- not to mention copiously rubbing on silver polish -- this instrument sounds and looks great: "I can't imagine a better example of an MB-4 than this," said Marc.

I am genuinely and thoroughly amazed, never expecting the sound to be as wonderful nor the instrument to be as enjoyably playable. Last evening my dogs were astonished by everything I played with it: Bach 2-part inventions alongside Scottish and English dance tunes. The Machaut/Kioulaphides "Douce dame jolie Variations" never sounded quite as medieval on my other mandos. Time and practice, of course, will be needed to get the most from this, but what a jolie road to travel!

I play my mandolin banjo on a regular basis. One thing I have found is that I need to dampen the unused bass strings with the heel of my picking hand. That cuts down on the sympathetic resonance of those strings and gives a clearer tone.