7 & 8 string Dobro/Shobro bridge question, help appreciated!

[Allen Kaatz]

I recently bought a McKenna 8 string dobro that sounds fantastic but I want to convert it to a 7 string, as the spacing of the strings is too cramped as an 8 string guitar. I was originally looking for a 7 string but then this one came along for a fair price, and 7 strings are hard to find.

The issue converting it to 7 seems to be the bridge -- I was in contact with Beard to get some parts (new 7-string nut and cone) and they wanted to sell me their offset spider. The problem I have with that idea is that then your intonation is off, ie the frets no longer indicate the correct intonation as the Beard spider is off by 1/4 inch. It can either be 1/4" sharp or flat depending on the orientation. The problem is the middle string of the seven would be right down the center which would be over the screw that holds the cone. Normally the dobro has a split bridge -- could a bridge be made that arches over the screw? That seems like an easier solution than the offset cone.

How were the original Shobros set up for 7 strings as a way to get around this problem?

[Howard Parker]

The offset spiders work fine. I've never played one that I could detect intonation issues, including the conversions.

fwiw

hp

[Allen Kaatz]

Thanks for your comment - which direction do you think it's preferable to orient the offset spider, to the back or front?

It's not the intonation per se I wonder about, it's whether or not the frets line up with that. I realize with any type of slide guitar it's mostly by ear but I like having the frets to go by.

[Howard Parker]

I think the bridge is oriented toward the tail.

You can call the Beard shop and chat with Paul if he's around.

He can be quite helpful and he's super pleasant.

h

[Larry Allen]

beard setup..bridge -7 degrees on the high string….

[Allen Kaatz]

beard setup..bridge -7 degrees on the high string….

Thanks Larry for the reply, but I'm not understanding this? -7 degrees of what?

[L. Bogue Sandberg]

I've owned both 7 string and 8 string McKenna's. The 8 is my everyday go on stage axe. I recently sold the 7 so it would get played. Greg built the 7 strings with the spider offset factored into the soundwell position, with the offset toward the tail. Dropping that offset spider into my 8 would certainly affect intonation. Think about barring versus harmonic at the 12th fret.

But since a dobro is just a trombone with strings, your ear may very well compensate, adjusting bar position for the slight error.

[Allen Kaatz]

I've owned both 7 string and 8 string McKenna's. The 8 is my everyday go on stage axe.

But since a dobro is just a trombone with strings, your ear may very well compensate, adjusting bar position for the slight error.

I do use the frets for a guide, so I guess it depends how far off they would be, 1/4" is a significant when it comes to scale length. Wish I had seen your 7 string when I was looking!

[L. Bogue Sandberg]

Allen,

I sent you a private message re: my old McKenna 7 string. It might be available.

Bogue

[Allen Kaatz]

I don't see why something like this wouldn't work, are there some drawbacks to doing it this way? I also wonder why bridge a couldn't be made that arched over the set screw for the cone? That screw doesn't need to be adjusted often does it, and it wouldn't be difficult to remove the saddle if needed - that way you could have the middle string dead center.

[Howard Parker]

Two reasons:

Premature tail failure on strings 1/2

The string spacing in your photo is clearly different between the top 4 and bottom 3 strings.

h

[Allen Kaatz]

Two reasons:

Premature tail failure on strings 1/2

The string spacing in your photo is clearly different between the top 4 and bottom 3 strings.

h

Yes I could see that - but what about the idea of the saddle arching over the screw?

[Howard Parker]

String 4 should run down the geometric center of the guitar to prevent lateral cone shift.

But heck, that's just me.

Did you call Paul?

h

[Allen Kaatz]

Paul was busy when I called and was supposed to call me back, which never happened. I'll have to try them again. What I'm talking about would be a long saddle that goes above the cone screw, so the string would be in the center.

[Howard Parker]

How would you accomplish cone tension adjustments over time?

You'd have to remove the insert, yes?

h

[Allen Kaatz]

How would you accomplish cone tension adjustments over time?

You'd have to remove the insert, yes?

h

Right, but how hard would that be? Seems easier than getting a new offset spider and dealing with the intonation.

[Howard Parker]

I think we have differing approaches as to spider bridge setups, etc.

Interested to hear what you decide to do.

h

[Allen Kaatz]

Yes - I need to talk to Paul about it.