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Sympathetic Resonance Too Much?
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=54416		 Page 1 of 1
Author:  RusRob [ Thu Sep 16, 2021 6:59 pm ]
Post subject:  Sympathetic Resonance Too Much?
I am curious if there is a way to control sympathetic resonance of strings?

Some of you may have seen my request for help on my Gibson CF 100 in the restoration and repair section. I Got the neck reset and let the guitar settle in and did the final setup on it. I am really pleased with how it plays and sounds, however the thing I notice is this guitar seems more sensitive to sympathetic resonance, or sympathetic vibrations of the un-muted strings. Tuned to Standard tuning it is really noticable.. maybe too much so. I have tried 3 different brands of strings, made a new nut and saddle thinking that could have a factor but nothing did it except tuning down a step which seems to help a bit.

I know this is something that some say is due to a very responsive guitar, and this is one of the nicest sounding guitars I own. It is just that it has this crazy "reverb" sound that just keeps ringing on unless I mute the bottom strings.


What I would like to know is changing the resonance of the guitar (adding weight or shaving braces) somthing that can effect this? When I put the new top on this guitar I "tuned it about 1/2 step away from the back. Assembled it brought the top and back closer togeter in tap tone but they are still different tones.

I know very little about tuning plates since I am just started on building #3 (#5 if I include 2 electrics) So I am not too sure why this guitar has such pronounced sympathetic resonance.

note:
(I did replace the top of this guitar with 60+ year old set of German Spruce ((they were cut and stacked 60+ years ago))


Any info would be helpful

Cheers,
Bob
Author:  Ken Nagy [ Fri Sep 17, 2021 7:23 am ]
Post subject:  Re: Sympathetic Resonance Too Much?
If it is a ringing sound, and not wolf's interfering with sound, I would think that you just mute the strings to stop it when you want to stop it, and let it sing when you want it to sing. Isn't that what guitars do? Mine are just acoustics and that part sounds cool; part of its signature. Is it somehow annoying on an electric? I've never played one.

Maybe I'm wrong and it really sounds hideous?

Sounds like you found some great wood.
Author:  jfmckenna [ Fri Sep 17, 2021 8:08 am ]
Post subject:  Re: Sympathetic Resonance Too Much?
Well, that's what I go for when I build a guitar so the only thing I can say is congrats! :)
Author:  banjopicks [ Fri Sep 17, 2021 8:15 am ]
Post subject:  Re: Sympathetic Resonance Too Much?
I have to agree with everyone that replied, that's fantastic and improved playing technique is the only thing required.
Author:  RusRob [ Fri Sep 17, 2021 1:24 pm ]
Post subject:  Re: Sympathetic Resonance Too Much?
Thanks for the replies gent's.

Ken Nagy wrote:
If it is a ringing sound, and not wolf's interfering with sound, I would think that you just mute the strings to stop it when you want to stop it, and let it sing when you want it to sing. Isn't that what guitars do? Mine are just acoustics and that part sounds cool; part of its signature. Is it somehow annoying on an electric? I've never played one.

Maybe I'm wrong and it really sounds hideous?

Sounds like you found some great wood.


No it isn't a wolf note, it is the open strings ringing at the harmonics. I had to fix a wolf note on a repair I did a while back (which was one note that was much louder that the rest).

I know that SR (Sympathetic Resonance) is a function of how guitar a guitar sounds but this creates almost a reverb sound where some notes just hang on for much longer than normal.

jfmckenna wrote:
Well, that's what I go for when I build a guitar so the only thing I can say is congrats! :)


I think if you heard this you would notice it. Where it is really noticeable is when I have to mute the offending strings, it is like you have a nice deep reverb on and you keep shutting it off.

Tuning down a step does seem to make it much better so that is how I have it tuned now.

I have read that putting 20/80 strings on helps, which is the set I have on now. Last night I stretched the strings out by tuning up a step and thrashing on them for a while. When I tuned it down (D#) it did seem to be better so I will just keep playing it and hope it calms down.

banjopicks wrote:
I have to agree with everyone that replied, that's fantastic and improved playing technique is the only thing required.


I have been playing for almost 60 years now and not sure this old dog can learn new tricks... LOL...
I do find that I play this guitar differently trying to accommodate this issue. So maybe that is what I will end up doing. I love the sound of this guitar and am not complaining about it but it is different than any other guitars I have or have owned.

Maybe this guitar is just meant to be tuned down a step..
Author:  jfmckenna [ Fri Sep 17, 2021 4:55 pm ]
Post subject:  Re: Sympathetic Resonance Too Much?
Is there a specific key or note that it happens on?

Also, if you just re-topped the instrument (if it was the repair you mentioned which btw you did a stellar job of) then what ever is happening there may age out too as the guitar breaks in.
Author:  RusRob [ Fri Sep 17, 2021 6:15 pm ]
Post subject:  Re: Sympathetic Resonance Too Much?
jfmckenna wrote:
Is there a specific key or note that it happens on?

Also, if you just re-topped the instrument (if it was the repair you mentioned which btw you did a stellar job of) then what ever is happening there may age out too as the guitar breaks in.


Yes it is just specific notes(s).

String_________Note_______String/Harmonic
4th____________E___________6___12
3rd____________A___________5___12
2nd____________B___________6___7
2nd____________D___________3___12
1st_____________E___________5___7
1st_____________G___________3___12

Also any notes I hit up the neck that fall on these same notes.

I would say that it is the 1st and 2nd strings that are the worst offenders.

You mentioned about break-in of the top. Yes I am hoping that this does settle in. Right now tuned down a half step seems to tame it pretty well but it would be nice to be able to tune it up to pitch with my other guitars.

Thanks for the compliment on re-topping. This is actually the first top I have ever done, I have replaced the back on a few guitars but this was a first for me. I figured it wouldn't be much different than a back except for the hole and the rosette, oh yea, and the bridge with all the geometry having to be right, and the sunburst... Well I guess they were different... LOL

Cheers,
Bob
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