A little off topic for this list but couldnt find a better one ( :
would appreciate rats comments




G'day all , I've been playing around with a composite mineral sand/epoxy
resin material for turntable plinths and spherical speaker enclosures.

please see my website @ http://members.optusnet.com.au/~lostwax1/ and browse
the td124pics

The plinth is very heavy (around 15kg) , the surface is a nice smooth black
texture and the material used has a density similar to zirconium
(4.5-4.8)..I'm definately no expert on the subject but I presume this would
be ideal for both plinths and speaker enclosures and hope it would deaden
any nasty unwanted frequencies stone cold..

I have been testing it with a td124 for well over six months now and it has
shown good potential lifetime with no signs of aging , leaching, smelling or
sagging....even in this ridiculous qld weather... : (

I would appreciate any feedback, good or bad, ideas etc....

Btw does anyone know of a decent speaker design guide for spherical only
speaker designs?

sean

Sean wrote:

A little off topic for this list but couldnt find a better one ( :
would appreciate rats comments

G'day all , I've been playing around with a composite mineral sand/epoxy
resin material for turntable plinths and spherical speaker enclosures.

please see my website @ http://members.optusnet.com.au/~lostwax1/ and browse
the td124pics

The plinth is very heavy (around 15kg) , the surface is a nice smooth black
texture and the material used has a density similar to zirconium
(4.5-4.8)..I'm definately no expert on the subject but I presume this would
be ideal for both plinths and speaker enclosures and hope it would deaden
any nasty unwanted frequencies stone cold..

I have been testing it with a td124 for well over six months now and it has
shown good potential lifetime with no signs of aging , leaching, smelling or
sagging....even in this ridiculous qld weather... : (

I would appreciate any feedback, good or bad, ideas etc....

Btw does anyone know of a decent speaker design guide for spherical only
speaker designs?

sean

Micheal Jones in Canberra, here where I am has been making concrete
spherical speakers for years,
very heavy, and he spin casts two halves, and glues them together.

Patrick Turner.

What is there to design? A sphere is a sphere. Just a matter of
size, surely?

Is there some reason why a sphere is a good shape for a speaker
enclosure? I can see some advantage from the point of view of the
loading of the material...cyclical tension/compression and very low
bending forces.

So why does it need to be stiff or heavy if there are no bending
forces? I think I have seen somewhere an argument for papier mache
spheres, and even expanded polystyrene. I guess, within the confines
of this particular argument, that a material needs to have a similar
modulus in tension and compression, and reasonable damping (elastic
and plastic).

But seems to me that, if the speaker is mounted on the circumference
(rather than a point source at the centre and no aperture) there are
unbalance fore-and-aft forces and so a need for both stiffness and
mass.

Once you need stiffness and mass, you might as well make the best
shape for the music. That cannot possibly be a sphere.

baffled, Ian


"Sean" wrote in message
u...
A little off topic for this list but couldnt find a better one
( :
would appreciate rats comments




G'day all , I've been playing around with a composite mineral
sand/epoxy
resin material for turntable plinths and spherical speaker
enclosures.

please see my website @ http://members.optusnet.com.au/~lostwax1/
and browse
the td124pics

The plinth is very heavy (around 15kg) , the surface is a nice
smooth black
texture and the material used has a density similar to zirconium
(4.5-4.8)..I'm definately no expert on the subject but I presume
this would
be ideal for both plinths and speaker enclosures and hope it would
deaden
any nasty unwanted frequencies stone cold..

I have been testing it with a td124 for well over six months now
and it has
shown good potential lifetime with no signs of aging , leaching,
smelling or
sagging....even in this ridiculous qld weather... : (

I would appreciate any feedback, good or bad, ideas etc....

Btw does anyone know of a decent speaker design guide for
spherical only
speaker designs?

sean

Sean wrote:

A little off topic for this list but couldnt find a better one ( :
would appreciate rats comments

G'day all , I've been playing around with a composite mineral sand/epoxy
resin material for turntable plinths and spherical speaker enclosures.

please see my website @ http://members.optusnet.com.au/~lostwax1/ and browse
the td124pics

The plinth is very heavy (around 15kg) , the surface is a nice smooth black
texture and the material used has a density similar to zirconium
(4.5-4.8)..I'm definately no expert on the subject but I presume this would
be ideal for both plinths and speaker enclosures and hope it would deaden
any nasty unwanted frequencies stone cold..

I have been testing it with a td124 for well over six months now and it has
shown good potential lifetime with no signs of aging , leaching, smelling or
sagging....even in this ridiculous qld weather... : (

I would appreciate any feedback, good or bad, ideas etc....

Btw does anyone know of a decent speaker design guide for spherical only
speaker designs?

sean

I have a TD-124/II - your plinth looks spectacular, but how do you deal with
rumble? My TD-124/II sounds good, and has stable speed, but rumble is way worse
than a modern table.

A sphere is the best shape for minimizing the effects of diffraction.
This was studied in detail by Olson of RCA labs, and is documented in
the Audio Cyclopeadia, first edition. There is a chart showing different
shapes of enclosures, and how diffraction affects off axis frequency
response. My guess is it was probably first published in RCA review, or
some other internal publication, which would be accessible at any major
technical library, and I've seen the little pictures reproduced in
countless other documents about speakers.

Ian Iveson wrote:

What is there to design? A sphere is a sphere. Just a matter of
size, surely?

Is there some reason why a sphere is a good shape for a speaker
enclosure? I can see some advantage from the point of view of the
loading of the material...cyclical tension/compression and very low
bending forces.

So why does it need to be stiff or heavy if there are no bending
forces? I think I have seen somewhere an argument for papier mache
spheres, and even expanded polystyrene. I guess, within the confines
of this particular argument, that a material needs to have a similar
modulus in tension and compression, and reasonable damping (elastic
and plastic).

But seems to me that, if the speaker is mounted on the circumference
(rather than a point source at the centre and no aperture) there are
unbalance fore-and-aft forces and so a need for both stiffness and
mass.

Once you need stiffness and mass, you might as well make the best
shape for the music. That cannot possibly be a sphere.

baffled, Ian

"Sean" wrote in message
u...
A little off topic for this list but couldnt find a better one
( :
would appreciate rats comments




G'day all , I've been playing around with a composite mineral
sand/epoxy
resin material for turntable plinths and spherical speaker
enclosures.

please see my website @ http://members.optusnet.com.au/~lostwax1/
and browse
the td124pics

The plinth is very heavy (around 15kg) , the surface is a nice
smooth black
texture and the material used has a density similar to zirconium
(4.5-4.8)..I'm definately no expert on the subject but I presume
this would
be ideal for both plinths and speaker enclosures and hope it would
deaden
any nasty unwanted frequencies stone cold..

I have been testing it with a td124 for well over six months now
and it has
shown good potential lifetime with no signs of aging , leaching,
smelling or
sagging....even in this ridiculous qld weather... : (

I would appreciate any feedback, good or bad, ideas etc....

Btw does anyone know of a decent speaker design guide for
spherical only
speaker designs?

sean

"Max Holubitsky" wrote in message
...


Sean wrote:

A little off topic for this list but couldnt find a better one ( :
would appreciate rats comments

G'day all , I've been playing around with a composite mineral sand/epoxy
resin material for turntable plinths and spherical speaker enclosures.

please see my website @ http://members.optusnet.com.au/~lostwax1/ and
browse
the td124pics

The plinth is very heavy (around 15kg) , the surface is a nice smooth
black
texture and the material used has a density similar to zirconium
(4.5-4.8)..I'm definately no expert on the subject but I presume this
would
be ideal for both plinths and speaker enclosures and hope it would
deaden
any nasty unwanted frequencies stone cold..

I have been testing it with a td124 for well over six months now and it
has
shown good potential lifetime with no signs of aging , leaching,
smelling or
sagging....even in this ridiculous qld weather... : (

I would appreciate any feedback, good or bad, ideas etc....

Btw does anyone know of a decent speaker design guide for spherical only
speaker designs?

sean

I have a TD-124/II - your plinth looks spectacular, but how do you deal
with
rumble? My TD-124/II sounds good, and has stable speed, but rumble is way
worse
than a modern table.

Thanks Max I'm glad you like it!, regarding Rumble , one of the reasons I
bought the td124 was its reported low rumble qualities. Mine is very quiet
and sounds superb even with the old shure MkIII.
have you checked the main bearing for wear and lubrication, I was told to
use a good viscous motor oil.

Regards Sean

Sean wrote:

"Max Holubitsky" wrote in message
...


Sean wrote:

A little off topic for this list but couldnt find a better one ( :
would appreciate rats comments

G'day all , I've been playing around with a composite mineral sand/epoxy
resin material for turntable plinths and spherical speaker enclosures.

please see my website @ http://members.optusnet.com.au/~lostwax1/ and
browse
the td124pics

The plinth is very heavy (around 15kg) , the surface is a nice smooth
black
texture and the material used has a density similar to zirconium
(4.5-4.8)..I'm definately no expert on the subject but I presume this
would
be ideal for both plinths and speaker enclosures and hope it would
deaden
any nasty unwanted frequencies stone cold..

I have been testing it with a td124 for well over six months now and it
has
shown good potential lifetime with no signs of aging , leaching,
smelling or
sagging....even in this ridiculous qld weather... : (

I would appreciate any feedback, good or bad, ideas etc....

Btw does anyone know of a decent speaker design guide for spherical only
speaker designs?

sean

I have a TD-124/II - your plinth looks spectacular, but how do you deal
with
rumble? My TD-124/II sounds good, and has stable speed, but rumble is way
worse
than a modern table.

Thanks Max I'm glad you like it!, regarding Rumble , one of the reasons I
bought the td124 was its reported low rumble qualities. Mine is very quiet
and sounds superb even with the old shure MkIII.
have you checked the main bearing for wear and lubrication, I was told to
use a good viscous motor oil.

Regards Sean


I used a very light oil for that bearing, and that's probably the source of my
problems! I guess I should get the old TD124 out of storage and fix it up!

thanks

Max