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Jul 14, 2020 - 1:25:09 PM
12 posts since 1/15/2015

I recently found and bought a 1970's rb250 "case queen". I have some questions and am having some tone issues that I'm hoping the experts here can point me in the right direction to fix. According to the seller, it was his sister's banjo that was purchased new in the 70's, exact year unknown. It has SN 204216 on the peghead along with Made in USA. I haven't been able to find that number series on the lists for year of manufacture that are frequently referenced here, but I certainly could have missed a good source. If anyone can identify the serial number to a year, it would be great.

No signs of wear at all on the fingerboard or frets, no buckle rash on the resonator, the binding is yellowed but not cracking or loose. The arm rest and tailpiece say Gibson and appear original. The truss rod cover has 3 screws, just FYI. It has the multi-ply rim that appears intact with no visible delamination. The seller installed a new Remo head, not sure why, and when I played it the sound wasn't very good and I suspected a loose head. I noticed the action was low but playable and noting/clarity seemed okay up the neck.

It appeared in good condition, was a fair price and I thought it could be made to sound and play lots better so I bought it.

I have a little bit of experience and enough confidence to do some basic setup steps and fixes, but I'm not an expert by any means. So here's what I've done so far:

First I checked the coordinating rods. The bottom one was loose, there was a gap of .030 - .060 neck to rim. I tightened the lower rod to bring the neck snug to the rim, checked that the top rod to neck was ok, and set both the other (nut) ends to neutral. That significantly lowered the action, too low, with strings barely off the frets. Then I checked the head tightness with a drum dial and it was quite loose, in the 75-80 range, so I brought it up to 90-91 all around. That raised the action some, still very low, no buzzing, BUT the 1st and 2nd strings sound dead, completely muted, starting about the 18th fret up to 21 but sound clearer at the 22nd fret. The 3rd and 4th string seem okay and 5th string is clear when fretted higher. I put a Purcell 5/8 bridge on it, so I don't think it's the bridge slots, but it could be I suppose. I checked neck relief by capoing at the first fret, fretting at the 22nd and checking for clearance at the 7th fret. I didn't measure it precisely, but it appears to be .010-.015 on the 3rd string with the other strings showing similar clearance.

Typically I read about action being too high, but this is really low, probably too low if I was playing hard, and the dead strings on those few frets are just not playable. According to the seller, the strings are new, so I have not replaced them yet. They seem to be light gauge. At head tension at 90, I'm still not sure it's at its potential and hoping for a lot better tone, but maybe strings and another bridge will help.

Any ideas on what I can look at next to get it working/sounding better, especially the action and noting the 1st and 2nd string in those few frets?

Thanks in advance.

Jul 14, 2020 - 2:08:47 PM
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1398 posts since 4/13/2009

Gibson didn't use a truss rod cover that required three screws, but almost all Asian makers did. A 70's era 250 had a bell-shaped cover.

Jul 14, 2020 - 2:09:53 PM

beegee

USA

21753 posts since 7/6/2005

It was made in 73,74, or75. Gibson never had a good system for numbering and there were some overlaps and duplicates when they changed numbering systems.  Like Dee says Gibson didn't normally  use 3-screw truss rod covers, but I did find a picture of a 1973 with a 3-screw cover. news to me.


Unless you are experienced in set-up, you may want to get someone who is to help you.
Head tightness is a major issue, but on these 70's Gibsons they had a nasty habit of tearing the flange bead away from the rim if over-tightened. I don't put a lot of stock in head-tightness numbers. Just make sure the head is tightened EVENLY all the way around and the the tension hoop has the same amount of hoop showing above the head at each hook.

The Remo head would be my choice, a quality 5/8-11/16" bridge and new strings.
I prefer the action to be 7/64" above the 12th fret.

The co-rods should be tight against the rim at the neck end and snug on the tailpiece end.
While the co-rods can be used to make MINOR adjustments to the action(per Gibson's instruction sheet since forever)most of us would rather adjust action by shimming the heel if the factory cut does not provide the proper action.

Check the nut slot depth and make sure there is enough clearance above the 1st fret so the strings don't buzz when played open. The truss rod should be adjusted so there is only a very slight bit of relief(bow) with the strings in place. Do NOT use the truss rod to try to adjust the action.

Edited by - beegee on 07/14/2020 14:19:29

Jul 14, 2020 - 2:28:21 PM

13102 posts since 10/30/2008

That deadness of the 1st and 2nd string on the lower frets make me ask "is there any BACK bow in the neck?" That would cause low action and poor tone on the lower frets.

Second question: are you dealing with new strings or the old case queen strings? Don't make any decisions on tone until you put on new strings.

I suggest you post a number of photos, close up of nut, fingerboard, pot, interior/exterior, etc.

We're presuming this isn't a bowtie RB 250. Please confirm.

Check the bead above your two piece flange's tube. Has it already broken away? Could cause tone issues.

Jul 14, 2020 - 2:41:03 PM
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12 posts since 1/15/2015

Thank you @deestexas and @beegee for your responses. I added the info about 3 screws on the truss rod cover since I had seen that discussion come up in previous threads on RB250s and thought it might be a useful data point that there’s one more Mastertone with three screws and it may help identify the year of manufacture. The cover is bell shaped and has screws at each corner.

@beegee, you mentioned shimming the neck, what is a good material to use as a shim? I suspected that the gap changed the neck angle and raised the action using string tension and allowed those strings to sound clearer.

Jul 14, 2020 - 2:48:27 PM

beegee

USA

21753 posts since 7/6/2005

Shim material is a popcorn-munching topic. There are those who like metal feeler gauges that can be stacked for a precise thickness. Others say you should use the same wood as the neck. Others like brass. Others might insist on submerged wood from sunken Great Lakes cargo ships or wood from ancient Buddha statues. I try to make it simple. I prefer to use old credit or loyalty or gift cards for the following reasons:
1. They are dense, don't compress much
2. They are readily available
3. They can be cut to shape with scissors
4. They are inert
5. They are usually of sufficient thickness to make the proper adjustment

I cut the card to fit the profile of the neck sides and punch a hole in the middle so I can mount it on the appropriate lag screw so it stays put. Make sure you have made your final selection for bridge height before finalizing the shim.

Edited by - beegee on 07/14/2020 14:51:57

Jul 14, 2020 - 3:00:31 PM

54 posts since 12/5/2015

Did the banjo come from the USA.

I thought Gibson banjos did NOT have "made in the USA" stickers unless they were shipped out of country....

Anyway, I recently acquired a Deering Golden Era from a former banjo student. He hadn't played it much (probably less than 100 hours). When I first got it, it had light gauge strings, loose head and no tone.

I put medium strings on it. I tightened the head several times (I use a torque wrench) on several different occasions.

I play the sugar out of the banjo. I put easily 100-200 hours on it and it now is beginning to sound great.

Keep tweeking the banjo. I was able to come across some maple shim material, in a piano I took apart. Hardwood shims would be more natural. Plastic cards will work as well. Good luck!

Jul 14, 2020 - 3:27:53 PM

10930 posts since 6/2/2008

I don't know if the three-screw truss rod cover signifies anything other than a replacement or a rare original item.

An original 70s Gibson neck is laminated from three pieces of mahogany (not counting the peghead ears). The center piece is fairly wide and easily visible. With that feature present, you can be confident you have an authentic Gibson neck. I've never read of anyone copying the 70s necks.

These banjos are for playing, not investing, so I don't think the truss rod cover matters much.

If you don't like the idea of shimming, just try a .656 bridge. I did that on a banjo with built-in extremely low action. Easy fix.

My heavily modded 70s RB-250 sounds best to my ear with the head at 91.  It had recently slipped below 90 and I noticed the sound was not what I was expecting. Was happy to discover it was just the head needing tightening.

To address someone else's comment: "Made in USA" on these isn't a sticker; it's stamped into the peghead beneath the serial number. All the RB-250s had that for a while. Mine does.

Enjoy.

Jul 14, 2020 - 4:05:30 PM

12 posts since 1/15/2015

Great feedback and encouragement

@beegee Thanks for input on using credit card stock. I'll try that after I get a taller bridge. I'll bet that will help a lot. The action is 5/64 at the 12th fret, so it needs to be higher for me.

@Old Hickory Yes the neck is a three piece lamination, and you're right it's just for playing. The truss rod cover is just a data point for others that have engaged in the discussion on whether Gibson ever used 3 screws in the cover. Several people have said in previous threads their RB250 had 3 and this one does too. I'll bump the head to 91, get a taller bridge and shim the neck if still needed. Thanks for the help.

Jul 14, 2020 - 4:39:43 PM
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beegee

USA

21753 posts since 7/6/2005

Gibson stamped "Made in USA" starting in 1970. In 1975-76 they wend to a gold-colored sticker with an 8-digit number that included Made in USA on the sticker.

I'd be curious to see inside the truss rod pocket

Jul 14, 2020 - 5:22:13 PM

4507 posts since 11/20/2004

Just a couple of thoughts. Looking from the tailpiece end, is the fingerboard level with the head? If so, it sounds like the 22nd fret may be a little high on the lower side, causing your muting on those strings. Higher action will help, but I would still remedy that issue if it were mine.

Jul 14, 2020 - 5:48:55 PM
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Players Union Member

RioStat

USA

5233 posts since 10/12/2009

Just to show that inconsistentcy is/was a hallmark of Gibson....

Here's my 1974 Gibson Gospel guitar, with a 3 screw truss rod cover, and my 1974 RB250, with the more common 2 screw truss rod cover !




Jul 14, 2020 - 8:00:47 PM

10930 posts since 6/2/2008

quote:
Originally posted by beegee

Gibson stamped "Made in USA" starting in 1970. In 1975-76 they wend to a gold-colored sticker with an 8-digit number that included Made in USA on the sticker.


Learn something new every day.

Jul 16, 2020 - 9:13:38 AM

12 posts since 1/15/2015

@beegee I was going to take a picture of the truss rod socket that you asked about, but found one of the cover screws has something in the middle of the Phillips socket that prevents the screwdriver tip from fitting. I’m attempting to post pictures of that. I think I can cut a slot with a dremel for a flat blade screwdriver and will take a picture of the socket after I get the screw out and the cover removed.


Jul 16, 2020 - 1:09:10 PM
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12 posts since 1/15/2015

beegee I was able to remove the cover. Here are a couple pictures of the truss rod socket.


Jul 18, 2020 - 9:04:59 AM

10930 posts since 6/2/2008

Mine looks just like that, except the truss rod cover was the more typical two-hole. The cover was pearl, not the original plastic.

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