Official Luthiers Forum!

[quote="Maybe we should start another discussion on this for those who have watched it already.[/quote]

I think that would be a great solution! All questions (and hopefully some answers) about the video in one thread.
A sort of "after sales pat-on-the-back-you be allright thread..."

Maybe Alan could kick off such a thread with a list of articles/books you have to read (before you watch).


Kind regards,


Edzard

I don't know if there are articals that you "have to read"before watching the tape. He does a pretty good job of explaining the basics that you can grasp the idea and get you on your way and started. But a suggested reading list might be helpful to save some googling time. I know that link I posted above is one to read.

Chris; Some Re: Big Red Book Of Lutherie #1 Basics of air resonances...W.D. Allen,Radiation from lower guitar modes...G.Caldersmith,Dessolving the mysteries...G.Caldersmith.
Big Red Book#3 Free plate tuning... Alan Carruth
Big Red Book#4 Paradoxes in guitar acoustics...Alan Carruth

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A person who has never made a mistake has never made anything!!!

I was glad that I read Alan articles in American Lutherie (nr 28,29 and 30). It gave me more perspective on the subject. But then again, I like to read the book before I go to the movie...

I bought "the" signal generator from Don Bradley, he included a nice bibliography of plate tuning. Maybe that's an idea for the 2.0 version of the DVD: a pdf file with a bibliography.

There is a lot of information in the Catgut Acoustical Society Journals. But there a many, many of them and it would be nice to have a overview of articles that really matter (to this subject).


Edzard.

Thanks Wes, Looks like I will just have to get the complete Big Red Books for my library.
How much is the tone generator? I've downloaded a trial generator to my old laptop and tried using it through my old Sony boom box but I don't think it had enough power. I was wondering if I could use a old car radio/tape player with a 12vdc powerpac and a 4" speaker. Might be able to pick one up cheap at the junk yard.

How do you get in contact with Don Bradley of Bradley engineering? Can you email him?
Does anyone know if a 25watt PA amp will work for a driver? Or a source of a 25 watt amp for this purpose?

That should be plenty. Protect your ears!! And you might want to protect your dogs ears too.

Don's contact info is:

Bradley Engineering
P.O.Box 141
Forestville CA 95436
(707) 887-9746
sonomadb@sonic.net

Thanks Alan.

I bought the signal generator from Don Bradley. Yesterday it arrived.

I will give a small review tomorrow with some photo's.



Edzard

I can get a car radio/tape for $10 and I was wondering if it's say only 15 watts per channel then if i wire the speaker to 2 channels will that give me 30 watts. Do those radios work that way?
Would these speakers also work?
http://www.google.com/products/catalog? ... ps-sellers

I'm not an expertbut I don't think you need 25 watts of power. My setup worked fine.....and I came from my computer headphone outlet on the front of the PC to an old set of small computer speakers with built-in amplifier (these were being thrown away at work as they were so cheap....and old) Anyhow, that small cheap amp built into those speakers (that normally drove 2" speakers) worked fine to drive a 4" speaker I removed from an old set of speakers I had here at the house. The 4" speaker was from an old stereo that cost my roughly $100 at Best Buy and the CD player has went out. I'll bet Radio Shack might have a cheap speaker that would work if you don't have an old speaker to rob.

Chris, I'm sure those speakers would work....but the tweeter will just get in the way of the air movement tha twill be driving the top so I would guess they would work better if the tweeter was removed. They are rated for a lot of power.....may take a good size amp to drive them.

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Formerly known as Adaboy.......

I tried to drive a top through my boom box with the speaker and it wouldn't drive it so my next thought was the car radio. I'm trying to get this on the cheap if you know what I mean. I just don't have the cash for the stand alone generator. I've been laid off since the first of the year so I have to be frugal for awhile. My guitar building card is up to $1500 and I've had no hits on my Tele and Strat on Craig's list.
I'll check radio shack.

I've been googleing 4" 30 watt speakers and nothing is coming up and Radio Shack was a bust.
Anyone have a source of a speaker out there?

Don't know anything about this outfit.

http://www.parts-express.com/wizards/searchResults.cfm?srchExt=CAT&srchCat=573&CFID=13082041&CFTOKEN=17241889

I googled hi-fi speaker kits. Also 4" woofer.

Old hi-fi amps or receivers with 30 watts/channel can be found at garage sales and thrift stores. ebay too, just don't go for any of the collectible old Pioneer or Marantz.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

I'll check out some thrift stores tomorrow. I checked one yesterday but no luck.

Back to the reading material. This is pretty good stuff.
http://www.ukuleles.com/Technology/statmeas1.html
That's a page from the site. Left Brain Luthier author.
http://www.ukuleles.com/Sales/building.html

Got my DVD today.

Thanks Michael.

Bob

I have not been able to shake a top yet either using garage sale speakers , you will need a speaker that responds from about 70 hertz on up. you will also need enough of an ohm rating, if the ohms are too low the power goes to drive the speaker . I just bought one from parts express, rated 8 ohms actauly 6. I hope thats enough , I will let you know as I need some connectors from radio shack. http://www.parts-express.com/pe/showdet ... N=81500637 Jody

I think the speaker impedence is suppose to match your system. Let us know how it goes for sure!

still not getting it, I have it hooked to a sansui 85 watt reciever,its probably not 85 watts per channel, just total output... I need more power , I am getting the tones, but not at the amplitude needed to shake the plates. Jody

Oh that can't be right. 40 watts is far more than enough. Where do you have the supports, if the supports are not at nodes they dampen the plate.

This is from the "Left Brain Luthier" and it seems the plate is supported by rubber bands. Anyone else using a setup like this?
I didn't have much luck finding a reciever at the thrift sores today and I'm thinking about making a quick frame and putting my home system speaker under it in the living room to see if I can get anything. I mean how can I tell if the tone generator is working like it's suppose too? If it's not putting out the correct signal how would I know?

i just have 1/2 of an adi top supported at the four corners, upon inverted large head bolts, maybe its a problem with the amp , i borrowed it from a friend who had it in his garage its not loud enough , I would have no problem taking the ear protection off, off and running the thing through the spectrum.I do have a decibel meter , Maybe Alan can chime in here and give us an idea how many decibels of sound is needed to drive the plates Thanks Jody

Jody,

From a previous post, in this thread, IIRC , you mentioned the model # of your Sansui and it is rated at 85 watts per channel.

The tone should sound pure, like an early synthesizer, perhaps even unpleasant. My guess is that your supports aren't allowing the top to move or your speaker isn't putting out enough. If the speaker is being overdriven, it won't reproduce the sine wave and it might not be able to drive the top. My supports are foam pyramids, from dark packing foam, about 1" high. That's not required, but it works for me. Placing them in the wrong spot shouldn't keep you from getting the top to "light up".

By the time the speaker puts out 15 or 20 watts, it will be VERY loud, perhaps painful. If your setup doesn't do that, you're not getting enough out of the speaker.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com