The Acoustic Guitar Forum

Go Back   The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Archtops

Reply
 
Thread Tools
  #1  
Old 11-03-2009, 12:46 PM
zombywoof zombywoof is offline
Registered User
 
Join Date: Apr 2007
Posts: 9,356
Default Why Not A Soundpost In An Archtop

While I may be in danger of submitting the world's dumbest post, why not put a soundpost in an archtop guitar? It surely seems like getting one in there and positioning it would be a royal pain in the butt but it also seems that it would make sense in terms of transmitting vibration.
__________________
"You start off playing guitars to get girls & end up talking with middle-aged men about your fingernails" - Ed Gerhard
Reply With Quote
  #2  
Old 11-03-2009, 01:04 PM
devellis's Avatar
devellis devellis is offline
Charter Member
 
Join Date: Nov 2007
Location: North Carolina
Posts: 8,399
Default

The short answer is because it's a guitar, not a violin. It's a reasonable question to ask, though, and until I read up on it, I wondered pretty much the same thing.

The mechanics of fretted/plucked versus bowed instruments are quite different. As a mandolin player, I'm aware that manufacturers of arch-topped instruments have, from a very early time, tried to claim the similarities between arched-topped mandolins and violins. Long before Gibson thought up the idea, mandolin companies were touting ther wares as the Stradivaris of the mandolin world. They even put f-holes on the mandolins (and archtop guitars, of course).

Mechanically coupling the top and back turns out to be a terrible, volume-killing idea on mandolins (and likewise, I suspect, on the archtop guitars which follow similar principles). Having the air inside the body acting as a plastic coupler seems to work far, far better than any rigid post does. Patterns of plate vibrations in the tops of fretted vs bowed instruments are markedly different, as I recall reading somewhere.

Long story short, it's been tried (at least in mandolins) and deemed an uncontested failure.
__________________
Bob DeVellis
Reply With Quote
  #3  
Old 11-03-2009, 01:22 PM
Wade Hampton Wade Hampton is offline
Registered User
 
Join Date: Sep 2008
Location: Chugiak, Alaska
Posts: 31,164
Default

I'll just back up Bob here by saying that he's correct in every detail, and will amplify further by providing the explanation I was given when I first asked about this.

What it comes down to, in the end, is the fundamental difference in providing the energy to the strings by using a bow or by using a plectrum or fingers. The plectrum and/or fingers provide that energy in essentially staccato bursts every time they strike the strings, but with a bow the energy delivery is much more continuous. Bowing is actually a considerably more efficient way to deliver that energy, or so I've been told. In any event, soundposts work with the continuous energy provided by a bow, but don't work with the staccato attack of a pick or fingers.

Hope that makes sense.


Wade Hampton Miller

PS I have heard some fretted instruments that had soundposts in them: a couple of dulcimers and a mandolin. They were abject failures as musical instruments in each case, though one eager dulcimer-builder who trying to sell me a soundpost-equipped dulcimer kept telling me: "You're just playing it wrong!" Naturally, when I handed it back to him to show me where I was screwing up and how my technique might be improved, he couldn't do any better.

No sale....
Reply With Quote
  #4  
Old 11-03-2009, 01:36 PM
gmm55 gmm55 is offline
Registered User
 
Join Date: Feb 2008
Posts: 841
Default

As a violin luthier, but one whose first instrument (to play) is the guitar, I have also been fascinated with this idea, enough that I have experimented with soundposts in guitars.The idea that a soundpost in a guitar is an uncontested failure is far too broad a statement. Certainly not all guitars are in need or will benefit in some way, but there are some that can.

The first thing to recognize is that placement of the post in a violin is a critical procedure, subject to altering the violin sound with even minute variation in position, quality of contact, or force, and there is no reason to suspect it should be any easier in a guitar. In fact, it will be more difficult to find an optimum position, because there is no obvious zone or location, such as there is with the violin. In other words, just sticking in a post haphazardly in any old place and declaring the result an unmitigated disaster is hardly the last word on the idea.

My general take is that there are indeed a few guitars that might benefit from a soundpost, either to improve the tone, or to cause the guitar to have a different sonic signature. In fact, I have one in a jumbo acoustic at the moment. It strengthens the tone and increases overall volume on this guitar. I have others that do not seem to benefit from a post.

For anyone inclined to experiment, a first principle of positioning would be to put the post on the treble side. It does not need to couple the top and back that much to make a difference. In other words, putting a post under the bridge would likely not have a positive effect, on an acoustic anyway, so think about keeping it closer to the ribs. One only needs to change the guitar's modes a little bit to have a fairly large change in sound. The neat thing is it is completely reversible, and allows one to change the tone fairly easily.
Reply With Quote
  #5  
Old 11-03-2009, 01:45 PM
devellis's Avatar
devellis devellis is offline
Charter Member
 
Join Date: Nov 2007
Location: North Carolina
Posts: 8,399
Default

Quote:
Originally Posted by gmm55 View Post
As a violin luthier, but one whose first instrument (to play) is the guitar, I have also been fascinated with this idea, enough that I have experimented with soundposts in guitars.The idea that a soundpost in a guitar is an uncontested failure is far too broad a statement. Certainly not all guitars are in need or will benefit in some way, but there are some that can.
I stand corrected. Sorry for the sweeping generalization.
__________________
Bob DeVellis
Reply With Quote
  #6  
Old 11-03-2009, 01:58 PM
Christian Reno Christian Reno is offline
Registered User
 
Join Date: Dec 2008
Posts: 978
Default

I was under the impression that Gretsch has used soundposts on some of their electric arch tops.
Reply With Quote
  #7  
Old 11-03-2009, 02:12 PM
unclrob unclrob is offline
Registered User
 
Join Date: Sep 2009
Location: Tallahassee Fla.
Posts: 150
Default

I remember doing a repair on an old 40's Harmony or along these line's that had an X brace and a sound post along the line's of an I beam made out of spruce,so I know its been done before and was original to the guitar.gmm55 is so right in positioning a sound post in violin,a mm off and you've changed the tone completely.gmm55 a question for you the gentleman who taught me violin repair spent a lot of time with his clients adjusting the thickness of the post,I was just wondering as a builder how much does the thickness really effect the tonal stucture?I ask because its been 20 years since I spent time learning under him and most of the violin work I get now is resetting sound post replacing bridge's and other assorted upkeep.
__________________
My tools-Larrivee OM03PA and J05,72 Harmony made Fender 12 string,Guild JF30 6+12,Stagg E/A,Guild Starfire bass,a couple of Tele's,65 Gibson L48 and a 49 L7,mando,balzuki,a couple of Gretsch's,72 Fender Princton Reverb,Ultra Sound AC30 and a bunch of other toys.
Reply With Quote
  #8  
Old 11-03-2009, 02:14 PM
PWoolson PWoolson is offline
Registered User
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 2,706
Default

Quote:
Originally Posted by Christian Reno View Post
I was under the impression that Gretsch has used soundposts on some of their electric arch tops.
They have, but the purpose is to suppress feedback. Getting the two plates moving in unison helps with that.
__________________
Paul Woolson
Reply With Quote
  #9  
Old 11-03-2009, 02:41 PM
gmm55 gmm55 is offline
Registered User
 
Join Date: Feb 2008
Posts: 841
Default

Quote:
Originally Posted by unclrob View Post
gmm55 is so right in positioning a sound post in violin,a mm off and you've changed the tone completely.gmm55 a question for you the gentleman who taught me violin repair spent a lot of time with his clients adjusting the thickness of the post,I was just wondering as a builder how much does the thickness really effect the tonal stucture?I ask because its been 20 years since I spent time learning under him and most of the violin work I get now is resetting sound post replacing bridge's and other assorted upkeep.
Hi Unclrob. In my experience, soundpost thickness is a parameter that is swamped by other things like position (laterally and longitudinally), post compression or force (changed by moving the post laterally), and quality of surface contact on the tables (which should be as close to 100% as possible) so much so, that any one of these changes will swamp any effect of diameter, providing one is within the normal range. The post diameter is fixed on the large side, since it has to enter the instrument through F holes. Going very thin could change things audibly, but not for the better in my experience. I tend to change inordinately thin posts for thicker ones.

Here is the problem. Let's say one takes out the post to thin it. It is impossible to duplicate the previous position with sufficient accuracy to guarantee a correct attribution of any changes. In other words, your instructor says the sound changed because of the diameter, but the very act of removing it means the change could come from any of the reasons I outlined.

I stick to conventional high grade spruce soundpost material from luthier suppliers and concentrate instead on getting all of the other things right, which is enough to worry about.
Reply With Quote
  #10  
Old 11-03-2009, 02:50 PM
gmm55 gmm55 is offline
Registered User
 
Join Date: Feb 2008
Posts: 841
Default

I would also add that if it were possible to keep all things the same, and if there were any tonal changes to speak of with changes to diameter, they would come from changes to coupling, via the amount of surface to surface contact at the top and bottom and not from changes in the post's mass. Changes to post mass from thinning is entirely negligible.
Reply With Quote
  #11  
Old 11-03-2009, 03:12 PM
Jeff M Jeff M is offline
Registered User
 
Join Date: Sep 2000
Location: Not where I thought I was going, but probably where I need to be.
Posts: 18,603
Default

Interesting you should ask.
I recently purchased a used archtop that I had sent from the shop to the luthier who built it.
He bult the guitar 14 years ago, with a soundpost.
One of the things he is doing to the guitar, along with giving it a good going over, is removing the soundpost and voicing the bridge..
I wanted to enhance it's acoustic properties of the guitar.
He noted the guitar sounds way better.

Hopefully get it soon to find out for myself.
__________________

"Use what talents you possess; the woods would be very silent if no birds sang except those that sang best."
Henry Van Dyke


"It is in the world of slow time that truth and art are found as one"
Norman Maclean,
Reply With Quote
  #12  
Old 11-03-2009, 03:37 PM
Wade Hampton Wade Hampton is offline
Registered User
 
Join Date: Sep 2008
Location: Chugiak, Alaska
Posts: 31,164
Default

Quote:
Originally Posted by devellis View Post
I stand corrected. Sorry for the sweeping generalization.
You're not the only one generalizing - I'm guilty of the same thing.

I do stand by what I wrote about the plectrum instruments with soundposts in them that I've heard, though. They were not impressive, not at all.


whm
Reply With Quote
  #13  
Old 11-03-2009, 03:43 PM
unclrob unclrob is offline
Registered User
 
Join Date: Sep 2009
Location: Tallahassee Fla.
Posts: 150
Default

gmm55 Thank you I only had 5 years with him before he past away and most of that if not all learning repairs,its always good to get more info in my book.So thanks again.
__________________
My tools-Larrivee OM03PA and J05,72 Harmony made Fender 12 string,Guild JF30 6+12,Stagg E/A,Guild Starfire bass,a couple of Tele's,65 Gibson L48 and a 49 L7,mando,balzuki,a couple of Gretsch's,72 Fender Princton Reverb,Ultra Sound AC30 and a bunch of other toys.
Reply With Quote
  #14  
Old 11-03-2009, 04:28 PM
gmm55 gmm55 is offline
Registered User
 
Join Date: Feb 2008
Posts: 841
Default

Wade, the instruments you mentioned would have a relatively small internal volume and thus higher fundamental body resonance, and my intuition is this has some bearing on why posts in them would not be effective. I think the instruments most likely to benefit from a post would be those with much greater volume, i.e., guitars. Of course violins have a small volume, but you already pointed out the main distinction with respect to continuous energy input from bowing.

Further, the likely candidates would have existing tonal problems of some kind, mostly those that sound sluggish (slow or weak attack) or boxy (kind of hollow sounding) and/or those that are too light of a build. Here, the post would be reducing response time and making smaller (actually changing) those large modes that are the source of the hollow sound. I cannot see any bright guitar or one lacking in bottom end benefitting from a post in any way.

I should add I have very little experience with semi-acoustics or archtops, but if I were to guess, I would say all bets are off when magnetic pickups and amplification becomes part of the equation.

Last edited by gmm55; 11-03-2009 at 04:39 PM.
Reply With Quote
  #15  
Old 11-03-2009, 07:29 PM
Wade Hampton Wade Hampton is offline
Registered User
 
Join Date: Sep 2008
Location: Chugiak, Alaska
Posts: 31,164
Default

Well, it all sounds intriguing - in theory. I've met other guitarbuilders who also had very logical-sounding reasons for advocating soundposts in guitars. None of those people, however, have ever achieved any prominence in the field, and those well-known builders with whom I've discussed the idea have tended to be dismissive of it.

So, in practical terms, anyway, there's no widely available acoustic guitar with a soundpost in it on the market that players can reasonably expect to find within an hour's drive of their home, so they can test out these ideas for themselves.

So, with respect, until I get my own hands on a guitar that has a soundpost AND sounds great, I'm afraid I'm going to have to file the concept under the category of "One of those ideas that SEEMS like it ought to work well, but doesn't seem to in real life..."


Wade Hampton Miller
Reply With Quote
Reply

  The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Archtops

Thread Tools





All times are GMT -6. The time now is 10:11 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright ©2000 - 2022, The Acoustic Guitar Forum
vB Ad Management by =RedTyger=