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Mark aka. Junk Box Instruments Male Wales United Kingdom: Share; Share on Twitter; Share on Facebook

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Simple amps
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Started this discussion. Last reply by tad adams Nov. 23, 2009.

Salvaging parts from an old piano
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Started this discussion. Last reply by Kurtisthall Sep. 15, 2009.

Uke strings
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Started this discussion. Last reply by Dave V Oct. 1, 2009.

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LittleBigOne commented on Mark aka. Junk Box Instruments's photo 'Cohiba cigar box amp - the works'

Hi Mark, I did some too and I have found an interesting tip maybe you will want to try. A few years ago I made some tests with measurements tools and found the speakers can give more sound when they can "pump" air. That is, you drilled little holes…

July 5

Mark aka. Junk Box Instruments added 3 photos to the album 'Instruments'

June 13

Mark aka. Junk Box Instruments added a photo

macanudo_3-string_fretless_1424

June 13

Mark aka. Junk Box Instruments added 2 photos to the album 'Instruments'

April 20

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At 8:15pm on July 5, 2010, petey twofinger said…: hey mark , inoticed you had mentioned that you check your solder work with a multimeter as you "go" .

how do i do this ?

i would definatly start this technique , but i cnt figure out how to do it !

thanks , petey .

At 11:45pm on June 21, 2010, Jason Johnson said…: Nice builds Mark......Keep up the good work. I just got videos up right now, not many good shots of my actual guitar Im using though.

At 10:33am on June 21, 2010, Zandi Z said…: Mark... you are absolutely correct in what you are saying. You obviously have given this much thought and study.
Refined instruments require awareness of all the various relationships you mention.. in fact, i can see you know more about it all than i do.

I am a novice builder, novice woodworker and novice musician.
I have only built a dozen or so instruments to date... simple,and rustic... made for learners and meditators... and so the proportions i speak of ARE very broad.

I do, however, use them as my starting points.
the logic behind it is simple...
i start with one of geometry's Invariant Proportions---
six radii can be inscribed within the circumference of a circle.
in Logic a circle is the symbol of an universe....
the instrument is the universe.
My rough analysis of all the various cordaphones i had to hand pointed me in that direction.

I have read of several people who did everything 'right', yet thought their build sounded like crap...
when i 'eye-balled' photos of their instruments where there were photos, i noticed that they seemed not to even take 'broad' proportions into account---sort of 'slap a standard scale neck on a pretty box' building style...
thing is, that works ok sometimes, too...

what i stated was a BIG simplification, undeniably so...
but, at my level of craftmanship, ENCOURAGING sympathetic vibrations is helpful to my purposes.

i would consider myself fortunate to reach your levels of refinement in my builds...

thanks for your response, Mark...... zandi z.

At 7:35am on June 17, 2010, Zandi Z said…: is a response to Mark aka Junk Box Instruments.

Mark wanted to know more about what i said about proportions... and do i measure or eyeball it ?

I do measure, but eye-balling is ok, too.

My basic premises are these:

'the box' is an amplifier.

'the stick', with hardware, is The Machine.

Why Proportions ?

the most efficient way to get the Box and/or Stick to resonate or 'amplify,' is to 'feed' them 'vibrating lengths' to which they might be most sympathetic....

this minimizes the energy needed to 'push' them to getting them to vibrate and to keep them vibrating.

The Box:

the length of the box is my Basic Unit... i generally round that out to an average between the inside length of box and outside length.

my Scale Length is a WHOLE NUMBER multiple of the Basic Unit.

eg: if BU is 8 inches, Scale Lengths would be 1,2,3,4,5,etc, times as long as the box...... 8 inches, 16 inches, 24 inches,32 inches, and 40 inches, etc.

The Stick:

i choose, or calculate a Scale Length...

i divide that Scale Length value by 4 to get a Stick Unit.

eg: 16 inch Scale Length = 4 inch Stick Unit.

Total Stick Length is equal to 6 Stick Units.

1 Stick Unit is headstock.

4 Stick Units from nut to bridge...(Scale Length).

1 Stick Unit from bridge to tail end.

The Result:

Scale Length is both proportional to the Box and proportional to the Stick .

the possibility of resonance is enhanced;

the possibility of dampening is reduced.

.....resonance is the most efficient way to transfer energy.

To Finish:

a person could place the center of the box directly under the bridge.

i prefer to mount the box so that the bridge sits from 2/3 to 3/4 of the way down the length of the box towards the tail....

i use movable bridges...

experimenting is a great part of this adventure...

i measured LOTS of instruments to see what their proportions were... then, i experimented lots.

thanks for asking, Mark...........zandi z.

Tags: proportions, resonance

At 12:19pm on June 14, 2010, JUJU AKA SOUNDSSOGOOD said…: Hi Mark thanks for the input mate i just read your message cheers

i know years gone by there were loads of little valve amps (battery powered) and you can still buy them from ebay ect but they go for silly money i would much rather have a crack at building my own all be it from a kit as i have never built a Amp in my life - but know what basic electrical components are and do ..well in a fashion lol! - i'm sure i could follow a drawing
what started me off on this was a video i saw on youtube a while since it showed a miniture valve amp rated at 1watt and boy did it sound fantastic the guy plugged it into a 12" speaker cab and it rocked
can't remember what the bloody amp was called but there available to buy but you guessed it Expensive i seem to thing it was around the £250-£300 mark - this amp i speak of fitted in the guys palm and was powered from a mains wall adaptor so i'm guessing it's pretty low voltage and as you mentioned a sealed lead acid battery may just do the trick - all i need to do now is find the Video and try and find out if theres any plans out ther for it - i'll keep you posted mate

cheers
juju.