Arch top vs Steel string sound

[pmatolcsy]

Hello all,

This is my first post on this forum. I wasn't sure if I should post it here or on the arch top section.

I'm designing my second archtop guitar. Every archtop I've ever played sounds different and to my ear at least, not as desirable as a traditional steel string acoustic. I realize that I have not played handmade Luthier built arch tops but even in recordings of high end arch tops I prefer traditional steel string acoustics. I'm in love with style of the arch top.
I've read Benedetto on arch tops and Somogyi on the resposive guitar.
So here's my question. Assuming Strictly Acoustic (no pickups), Identical Acoustic Strings, woods , body volume(including arch volume) , port areas , neck construction and joining stiffness,
what contributes most and in which order to the difference in sound? Identified differences which I am aware of are as follows:
Top thickness and or Thickness Gradient
Top shape(independent of body volume)
Port shape and position
Bracing Differences(Please consider X braced archtops only. I prefer the sound)
Bridge/Tailpiece Design and subsequent loading of the plate.
Grain Runout

I have my theories but I'm looking for others opinions.
Well Educated, Not so well educated (that's me) ,wild and drunken(not too often) guesses accepted

Thanks
Phil
p.s. can someone explain to me how to insert an image from my computer into a post

[Silly Moustache]

Hi,
To answer your last question. upload your images to photobucket.

Then click on the image to get (and copy the image location.

Go to your AGF message and click on the little yellow icon which puts up a box in which you paste the image location.

Re: the tone of archtops. It is my theory (which is my own) that earlier archtops - '20s- '30s were designed primarily to give that harsh incisive percussive rhythm sound that we associate with folk like Freddie Green.

Later ones - when jazz soloists became more common became more subtle,open and,frankly, musical.

I'm sure there are exceptions and of course my theory maybe wrong.

Hope that helps.

[pmatolcsy]

Thanks Silly

[Glenn23]

The majority of the difference is how the strings load the plate. In archtops the force of the deflection at the bridge and consequent compression of the top plate transfers far less energy than the full force of the strings terminating at the center of the soundboard.

[pmatolcsy]

Hi Glenn,

Thanks for the speedy reply.
I agree that the bridge/tailpiece design and break angle could play a huge roll in affecting the sound. Then the transmitted energy meets a much thicker and more curved plate on an arch top . Does this affect primarily tone or volume? Ken Parkers arch tops seem to have plenty of volume.
They have thin tops, arched in a more planar fashion and a very light and high but otherwise traditional arch top bridge. They sound more like acoustics than a "traditional" arch top , but its still not the sound I'm looking for.

phil

[Glenn23]

Think about a banjo and how loud and percussive its sound is. It instantly dissipates its energy. A banjo is one at one end of the spectrum, whereas a solid body electric is at the opposite end. A solid body is very quiet but the string vibrates for a very long time, slowly dissipating its energy.

[pmatolcsy]

So your saying an arch top is closer to a banjo in terms of its string energy dissipation than a steel string acoustic and that an acoustic is closer to a neck-thru electric. But a banjo also has a much looser plate(similar to a drum head) which is easier to excite than the body of a solid body. Your saying if I want an acoustic sound in my arch top, all I have to change is the bridge style. Batson Guitars makes an acoustic with a unique bridge that both provides the torque
of a flattops design and a tailpiece to take the tension of the strings. I believe it reduces the need for the bracing to accommodate direct string tension and allows lighter bracing . Ive thought of something like that for my arch top. But i'm still concerned about all the other differences between the styles and their relative impact on tone and volume.
Great Conversation
Thanks Phil

[M Hayden]

Buzz Vineyard built some archtops which had pin bridges a while ago. They sounded good - a bit more focused than most flat-tops, and warmer than many archtops. I do not know the specifics of his bracing but recall that it was unusual....

Sobell guitars, built with a very tight (12' or 15' AIR) top radius have many of the same characteristics.

[pmatolcsy]

Please describe focused for me.

[M Hayden]

When i say "focused," it indicates a bias towards treble notes with a timbre that cuts through the mix, and is relatively fat sounding - ooo rather than eeeee.

[pmatolcsy]

thanks M Hayden. That's an excellent description. Is it also known as projection? Trebley dooesn't sound like what I'm after , and although i.m open to all forms of sound one of my bandmates is very sensitive to that annoying trebely sound we call "ouch" . Think Buddy Guy. 99% of the time I'm the only guitarist so fat sounds good. I'm looking for steel string acoustic sound out of an arch top. But I want it to work in intimate groups as well as with my band. In the band setting it will be plugged in. I'm planning on using a transducer, and an LRBaggs Session DI to tone shape and suppress feedback. I have talked with them extensively and their product seems ideal for my "plugged in" needs. So I guess what I'm after is the unplugged sound in an intimate setting.

phil

[MC5C]

My current theory is that a lively and responsive back is very important to how an archtop sounds, light and delicate braces on the top, sound port in the upper bout puts the sound closer to the player, and no F-holes improves the action of the lower bout but on the other hand F-holes frees up the action of the lower bout while making the vibrating area smaller - conundrum. A high string break angle does not improve coupling of the string energy to the top, I think it dampens it by pre-loading the top excessively. I think that high tension strings can add to excessive pre-load, and I am awaiting delivery of some Newtone balanced low tension strings that have similar mass to "normal" strings but lower tension (thinner core wire and thicker wrap wire, or double wraps). I think that a string break angle of between 10 and 12 degrees is sufficient for best tone production. I think a one piece bridge made as light as possible is good. That's all I got...

[pmatolcsy]

Thanks M5SC
I'm with you on almost everything you said. Active backs,light construction,Playable Strings,sound hole location. I plan on making my tailpiece height adjustable.Right now fully down its 12 degrees but its easy to adjust up(one allen key)

[Richard Mott]

I think you should ask these questions of a top flight archtop builder, of which there are relatively few. My own sense is that there is not a simple, optimal measure for all of the variables you lay out--each depends on the others. For instance, optimal break angle and load depends on the stiffness of the top, which depends on the arch, graduation, bracing, and the properties (stiffness and weight) of the wood. The best archtops in my experience (Monteleone, Gilchrist, D'Aquisto ...) have plenty of sustain and warmth, but with greater punch, clarity, and speed of response than most flattops. And with unmatched evenness of harmonic decay. But these instruments are one in a thousand. I think Linda Manzer once referred to the archtop as the "Everest" of guitar lutherie, which captures the challenge of building to the true capacity of this instrument.

[iim7V7IM7]

A couple thoughts....

• Focus on the flattening the arch of your top and thinning your top plate
• With the flatter arch, you may need to revise your approach to bracing
• Consider and oval hole vs. f-holes, but careful to manage the body resonance
• You may want to rethink and increase your rim depth
• The relationship of the back and top in an archtop differs from a flat top, some of what you seek lies in the back in my opinion
• You may need to rethink neck angle and tailpiece angle to better suit the correct down pressure on your top

These principles won't make an archtop sound like a flat top, however will increase the overtone content and bass response of an archtop over a traditional design. In simple terms, I would describe it as 75% archtop sound / 25% flat top sound. So you have the string-to-string clarity, fast attack, projection and decay of an archtop with added bass response and overtone complexity of a flat top.

If you are interested, check out this build thread. For what its worth, the luthier who attempted this project had built >300+ Traditional archtops.

http://www.acousticguitarforum.com/f...d.php?t=412255