A VERY scientific explanation of "Carbon Tone"

[Carbonius]

You guys ever read this http://www.rainsong.com/sound.html??? It's found on Rainsong's website. I read all of it as I like this kind of thing. Assuming everything stated is true, it raises a few questions:

• If the highs are not dampened as much, are Rainsong's really bright?
• I have NEVER found highs "muddy", but maybe this is why they appear too bright?? A distorted tone can seem louder simply because the tone is unpleasant.
• It seems like the article stated that you will hear MORE overtones, I hear less. I hear a lot of fundamental with some overtones. I actually find that there seems to be tones missing when I play carbon guitars. Like a dry mix.

Now I speak this as a guy who's only played 2 Rainsong's for a very limited time frame. It's possible I just didn't have time to adjust to it all. I did not find it bad at all, though I wish I could play a WS. I played a dread and the older APLE version. If the APLE had more bass and 2 more frets it would be home with me now!

[Earl49]

Interesting article, and thanks for posting the link Carbonius. I found it an interesting read, being an acoustical engineer as my day job. Guitar acoustics are a really complex topic, as was hinted in the article.

I've owned a WS-1000 since 2001, a PMJ-1000 (their first attempt a hybrid) since 2006, and now own several other CF guitars. I hardly ever pick up my rather nice wood guitars any more (mostly Taylor because I like their necks) especially when leaving the house.

The first Rainsong guitars had an un-braced unidirectional CF top. Then they changed to the woven fabric tops, which seemed to have slightly different vibration characteristics. Mine has a layer of foam inside (you can feel it starting from about 1/4" inside the sound hole) presumably to add damping and make it approximate the combined stiffness / damping properties of wood more closely.

The high frequencies not being damped so much is likely why the tone is described as "crystalline or bell-like". You hear some of the higher harmonics that get damped out in wood, so it changes the character of the sound.

[Doubleneck]

Originally Posted by Carbonius

You guys ever read this http://www.rainsong.com/sound.html??? It's found on Rainsong's website. I read all of it as I like this kind of thing. Assuming everything stated is true, it raises a few questions:

• If the highs are not dampened as much, are Rainsong's really bright?
• I have NEVER found highs "muddy", but maybe this is why they appear too bright?? A distorted tone can seem louder simply because the tone is unpleasant.
• It seems like the article stated that you will hear MORE overtones, I hear less. I hear a lot of fundamental with some overtones. I actually find that there seems to be tones missing when I play carbon guitars. Like a dry mix.

I think you are hearing it right, especially your last observation. I hear less overtones in carbon guitars. The sound is less complex, than a well made wood guitar. When I play my JM-1000 vs my McKnight the above is what I hear.

[Res Ipsa]

This is an interesting conversation.

I'll chime in -- no pun intended -- maybe it will add to the discussion of overtones.

I've recently been experimenting with materials I have on hand to see if it's possible to dampen the fundamental chime and increase the overtones in a couple CF guitars in my stable: an acoustic (Rainsong Shorty) and a CF electric guitar (Composite Acoustics Blade).

Experiments like this remind me just how much a role the soundboard plays, its material, dimensions and body style.

Don't laugh, but I'm getting interesting results with a J Bass metal bridge cover (ashtray style) affixed to the top of my soundboard. It stays in place with two strips of double sided foam tape, just behind the bridge.

I swear it softens the fundamentals. Also it seems to add a touch of reverb, or maybe some other sibling of the Overtone family. I think it adds volume too from my (player's) perspective.

The reverb effect on the electric guitar may be less pronounced, but the volume boost for acoustic play is huge.

Anyway, back to the regular scheduled program ...

Rez;

I've never run across a metal bridge cover, in part because most of my guitar experience has been with acoustics. After reading your post I did a search and now have an idea of what you are talking about--and have some questions.

First, if I understand you right you are not using the cover over the bridge. Rather, you have it below the bridge and it alters the tonal and projection qualities of both acoustic and electric guitars. This is interesting stuff. Have you attached a pickup to the cover to see if the differences are pronounced in electric mode?

Second, in looking at the various pictures of the metal covers, it appears that the covers are generally attached with screws. If so, does that mean you have to continually screw and unscrew the cover in order to change the strings? If that's the case, do any of the covers have a hinge arrangement to facilitate easy string change?

As you can probably tell, I know nothing about hinge covers, but I'm fascinated by your explorations.

[Res Ipsa]

Evan,

Thank you, and I'll do my best to explain further -

1. Yes, bridge covers -- as found on electric bass guitars (and some Telecaster electric guitars plus some lap steel electric guitars) -- are meant to cover the bridge, and typically must be removed in order to change strings.

2. On bass guitars the bridge cover is typically attached to the wood body of the guitar with two screws that are inserted through the flanges of the bridge cover. Telecaster guitars may use a different means of attachment.

3. In my experiments, I dispense with the screws and use double-sided foam tape stuck to the underside of the flanges of the bridge cover, which then sticks to the surface of the guitar's soundboard.

4. I mount the bridge cover about an inch behind the bridge, so it doesn't interfere with palm muting or changing the strings.

5. The bridge cover most definitely changes the aural "personality" of the instrument.

6. I suspect more than one thing is going on in these experiments: the vibration of the soundboard is altered by the additional mass and materials, and the bridge cover acts as a resonating chamber in its own right, directing a little more sound to the player's ear. As a result I perceive the instrument's sound to be more complex (and organic if I daresay).

7. I tried putting a cheap piezo pickup inside the bridge cover, but it was awful hissy and I ripped it out. A decent piezo might work.

It's fun to experiment like this, and it does no damage to the CF surface. If you don't have a bridge cover, there are other objects to try: a spoon, spatula, dull kitchen knife, a jar lid, even kitty's food dish. I found a recessed drawer handle at Lowes that sounded much like the bridge cover!

Grab some foam tape and have fun!

p.s. My latest incarnation is to tape two neodymium magnets to the soundoard. Any ferrous object - like a steel bridge cover - holds fast (an easy way to swap out different objects without prying off the tape each time).

Whatever method you use, beware of scratching the guitar as the magnets are really strong.

[Res Ipsa]

Here's a resonator bridge cover mounted (with magnets) to my carbon fiber electric guitar:

(hope the pics appear, first attempt at posting pics here)

[Res Ipsa]

Cool, it worked

And the Shorty. Found her on the porch, with a new voice.

This is a recessed drawer pull from the hardware store. Held on with double-sided tape. It surprised me that it works decently. It increases the volume to my player's ears. Also gives a rounder sound to the Shorty.

[Res Ipsa]

Apologies for hijacking this interesting discussion ... back to regular programming!

Res;

Thank you for the explanations and the photos. You are having way too much fun.

If you continue with this work, perhaps you should start a new thread?

[Res Ipsa]

Evan, nothing is better than enjoying the front porch on a lovely Sunday afternoon. Making the best of things, you know

Good suggestion, it may warrant a separate thread if this continues. I'd like to hear from others who experiment with acoustic augmentation.

[Earl49]

Res Ipsa, anything you do to the top to add stiffness (braces), damping (foam tape or a damping sheet), or mass (metal plate cover) will affect the tone to one degree or another. Your metal pickup cover or the drawer pull actually does some of each.

Applying the materials in different places will also affect tone differently. The vibration modes of guitar tops in their primary frequency range are highly localized. Just Google "Chladni patterns for guitar" and you will see how complex these patterns can get, and how they change with the forcing frequency (string pitch). Experimentation is fun!

[Res Ipsa]

Earl, thanks, I'll check it out, and thanks for explaining how this is working. You know this might lead to a CF-turned-steampunk guitar, what fun!