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I finished my guitar and most aspects of the guitar are as good or even better than I expected. Sustain, overtones, thick trebles, responsiveness. All great. The only thing I would wish is a little bit more bass.

How would you go about you and your guitar to get more bass? What are the most vital aspects in the design to get bass aside from air volume which I should have plenty.

Thanks for every and any input!

Main top mobility.

scalloped bracing is typically done for more bass response in guitars. The 'bassiest guitars I have ever built had tapered braces and thinned out perimeters. It's something I'm trying to figure out for a long time.

The easiest way is to kill the treble response with mass so you can more easily hear the bass that's there. But that's not really a good idea.

To actually get more bass, I think the most important thing is to keep stiffness as low as possible. One idea I've been exploring for smaller guitars is lower bridge height, to reduce torque on the soundboard so I can make the stiffness lower. Results seem promising so far, but more data needed to say for sure whether it's the way to go.

I think another good way to lower resonant frequencies is to concentrate the soundboard mass in the center. This is what Ervin Somogyi does, and he's well known for good bass. Very thin soundboard to keep the total mass low, but relatively heavy bridge/bridge plate in the center.

Mass loaded sides may help.

An easy experiment you could try on your finished guitar is a wood saddle instead of bone. Might tame the high frequencies a bit.

I am as far as you can get from being an expert but.... I did have a 1970's Guild that lacked bass. After years of thinking about it I finally took a small plane, reached in thru the sound hole and planed the X braces. It didn't take much and the bass picked up quite a bit. But get some expert advice first

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Joe Beaver
Maker of Sawdust

Was that one of those over braced Guilds with the three massive tone bars? I ask only because I am curious as I did the same thing to one of those once and the change in tone was very dramatic and much for the better.

It was a 72-73, D47 as I remember it, and yes it was heavily braced. I worked on the X brace.

If that is a possible fix in this case, only Joost knows.

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Joe Beaver
Maker of Sawdust

I have heard that a smaller sound hole favors more bass.

I've done the same thing on several guitars now. Excellent results every time. I work on the tone bars also, well as much as I can reach anyways!
I went a little too far on one guitar though. And it starts to poop out when strumed too hard. But it actually performs really great for light finger picking. I wonder if that's what people mean by voicing a guitar for finger-picking?

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Pat

As a fingerpicker who plays with acrylic nails, I can tell you that I am uncomfortable with any string height under .5" ... I have played small bodied Gibsons which were something like 3/8" string height at the bridge and found them ergonomically impossible.

Reduce the frequency of the T(1,1)1 and T(1,1)2 (that will also tend to increase monopole mobility); use a live back.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Before you do anything, you may want to wait a while--the tone of a newly built guitar develops.

As has been said, you can reach inside and plane various braces, though you risk getting them too thin. Posting a picture of the inside of the guitar, with details on size, scale, etc., might bring out some experienced people with suggestions.

The quickest and least risky method, of any I've personally tried, is tuning the back and top resonances closer, but not closer than a semitone. This is Alan Carruth's method. For me this really brought up the bass, and was easy to do, in the two guitars I used it on. And it's quick--shaving a little of the main back brace did the trick.

I think Alan has posted detailed instructions here on how to do this, but I was unable to find the post. I have saved an old MIMF post by Alan on this subject, but it's not in their archives.

There are helpful, though not detailed, discussions here:

viewtopic.php?f=10101&t=25664&p=345848&hilit=tune+top+back+resonance#p345848

viewtopic.php?f=10102&t=13200&hilit=tune+top+back+resonance

Maybe someone else can point to Alan's earlier step-by-step post?

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Tim Allen
"Never hurry, never rest."

As Trevor and Tim said, sometimes the most effective and safest way to get more bass from a guitar without messing up the treble is to remove some material from the back braces. It's also fairly easy to see if this might work without actually taking any material off. You can load the back with something like poster adhesive to drop the pitch of the 'main back' resonance, and try it out. If that gives you a sound hat's closer to what you want, then you can actually shave braces. Finding the most effective spot for the mass load also tells you where to reduce the braces. In general, since adding mass makes it harder to move the back shaving braces will be more effective, so go slowly there.

X3 with Alan...

I would leave the top bracing alone if you don't want to muck up your trebles.... You also do not want a "woofy" sounding guitar or a huge belly/crack/bridge pulled off from whittling too much on your top bracing.

You can shave your 2 lowest back braces and it generally gives the guitar a more full, rounded sound...

This is an instance where a microphone and a spectrum analyzer is useful... You can bonk and shave till the main back resonance is between 4 and 1 semitones above the main top... Don't get any closer than this.

It's not surprising to find that most guitars can start off with the main back at 10+ semitones above the main top.... But it doesn't take much back brace shaving to bring it in line.

Thanks