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I can't answer anything that's specific to Mario's bridge but your stated density for ABW as compared with BRW and AE sounds about right.

Trevor, I wasn't being a smartass; while lightweight may be best for responsiveness and power, it comes at a price in tone. Not everyone wants, or needs, or can use, the tone produced by an uber-light bridge. Personally, I -want- mine to be ultra lights, like you, but it's not for everyone.

As for the ABW VS BRW, I don't know where you got your 75% figure.... Most of my BRW stash is good, dense stuff, not all that much lighter than ABW. African Blackwood is also a true rosewood, BTW. At the end of the day, I still don't have a problem getting a ABW bridge to well under 20 grams...

According to the published numbers ABW can range from about 34%-78% denser than BRW so 75%, though on the high side, is within reason.

I don't use a ton of ABW but I'd estimate that the stuff I've used has averaged around 50% denser than the average BRW I've used.
I'd agree that I've had no problem getting it down to the weight range that I'm shooting for on steel string bridges. I don't think I'll be using it on any of my classical bridges, though, unless I come across some stuff on the it's low extreme for density.

Sure, and there are plenty of ways of changing tone. I perhaps should also point out that I'm building mainly fingerpicking guitars, so I'm not usually in the 13-56 ball park with a flatpick. Remember that it's easy to get more bridge mass by using heavier bridge pins, whilst it's not quite so easy to go lighter if you started out with a heavier bridge. Just tools in the tonal tool box.

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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

According to the published numbers ABW can range from about 34%-78% denser than BRW so 75%, though on the high side, is within reason.

Most "published" sources list BRW way, way too low in density. Yes, some of it is very light, but most sources list it as having a lower specific gravity, on average, than EIR's average, and that's just plain wrong. I'd estimate, going by what my bridges weigh, that the ABW I'm using is no more than 20% denser than the BRW I was using, and likely closer to 15%. I do have some very nice, light BRW bridge blanks, but my preference was for the densest ones. I've also tried Amazon RW for bridges, successfully. It's pretty much a dead-ringer for my densest BRW.

I would definitely NOT recommend ABW for a classical bridge, though. I doubt it would work well, even if whittled down to a reasonable weight.

It's all in the tape, Filippo! I recommend Aluminum Duct Tape! Shiny and light, sticks well.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Thanks to Al, Trevor, et. al for weighing in (pardon the pun) on the subject. I am captivated by the more scientific side of luthiery as it relates to building better instruments. This is one of the first discussions that has actually given me quantifiable concepts that I feel I can use in my building immediately. I feel that I am now equipped to make adjustments in the sound of my instruments based on specific changes that can be attributed to bridge design, weight, and material. Thank you all for the insights!

I usually buy the "B" grade African blackwood. Aside from being cheaper I think it is slightly less dense than the "A" grade stuff. I don't mind a fairly heavy bridge for a steel string, even for a fingerstyle guitar. I think it helps it ring longer. One thing I like about AB is that you can make it look like either a rosewood (which it is) or ebony (by oiling it).
I think stiffness is as important as weight for a bridge, and losing one at the expense of the other is not always a good thing. Having a design that allows each factor to be adjusted separately is not easy to find but is something to work toward.

Most of my bridges incorporate CF for exactly that reason.

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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

This brings up an interesting question.

For those who believe "lighter is better", do you use lightweight bridge pins, IE plastic or wood?

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Old growth, shmold growth!

Yup.

Actually I like light weight and light color

I think I'm gonna have to get into custom pin making, because light colored, unslotted, 3 degree wood pins are hard to come by. The boxwood pins that LMI sells are nice, but slotted. And I'd really like to have some even lighter colors too, like maple, holly and pecan. Looks much nicer against a dark bridge than ebony and rosewood, IMO. Don't know why maple pins aren't widely available... maybe too soft for slotted, and not enough demand for unslotted? But maybe if I can get a speedy lathe setup going, I could fill that void in the market