Slightly off the wall, but bear with me...

Whatever subs I end up with, there will come a time when the large 3-way
boxes I'm using at present will no longer contain bass drivers and will be
replaced. The replacement cabs will likely use the existing KEF B110 and T27
drivers.

I'd like the small cabs to be as free of possible resonances and similar
effects as is feasible. To this end, those Nautilus snail shell thingies
have interesting enclosures for the mid-range drivers - very non-box-shaped,
and there's no baffle board.

Assuming I'm able to fabricate an enclosure of this type, would the general
principle of a cylindrical cab with a rounded interior shape and no baffle
work well with my drivers? If so, what materials might be suitable? I
envisage a volume of around 8 litres, rough outer dimensions being 150mm
diameter and 300mm or so long. So far, I've considered the following
construction approaches...

Cut a series of rings out of MDF, glue them together to create a tapered
cylinder, then work them to get a smooth surface.

Mould the cabinets out of GRP. Could there be resonances with this approach?
If thickness will reduce them, how thick would be good enough? 10-12mm?

Make them out of some sort of resinous paste, perhaps using wire
reinforcement for the main structure and metal plates for fitting points.
How about car body filler for this approach? If not, what other paste-type
materials are worth looking at?


--
Wally
www.art-gallery.myby.co.uk
Moving soon to: www.artbywally.com

On Tue, 13 Jan 2004 15:16:59 -0000, "Wally"
wrote:

Slightly off the wall, but bear with me...

Whatever subs I end up with, there will come a time when the large 3-way
boxes I'm using at present will no longer contain bass drivers and will be
replaced. The replacement cabs will likely use the existing KEF B110 and T27
drivers.

I'd like the small cabs to be as free of possible resonances and similar
effects as is feasible. To this end, those Nautilus snail shell thingies
have interesting enclosures for the mid-range drivers - very non-box-shaped,
and there's no baffle board.

Assuming I'm able to fabricate an enclosure of this type, would the general
principle of a cylindrical cab with a rounded interior shape and no baffle
work well with my drivers? If so, what materials might be suitable? I
envisage a volume of around 8 litres, rough outer dimensions being 150mm
diameter and 300mm or so long. So far, I've considered the following
construction approaches...

Cut a series of rings out of MDF, glue them together to create a tapered
cylinder, then work them to get a smooth surface.

Mould the cabinets out of GRP. Could there be resonances with this approach?
If thickness will reduce them, how thick would be good enough? 10-12mm?

Make them out of some sort of resinous paste, perhaps using wire
reinforcement for the main structure and metal plates for fitting points.
How about car body filler for this approach? If not, what other paste-type
materials are worth looking at?

There was a design recommended by Wharfedale back in the sixties that
used a concrete drain pipe for exactly the purpose you describe. I'm
sure that with a little searching round the bigger plumbers you could
find something suitable.

d

_____________________________

http://www.pearce.uk.com

Don Pearce wrote:

There was a design recommended by Wharfedale back in the sixties that
used a concrete drain pipe for exactly the purpose you describe. I'm
sure that with a little searching round the bigger plumbers you could
find something suitable.

I remember something like that (with the driver mounted in the side rather
than on the end). I'll be having a wander round the local DIY to check out
their audiophile-quality garden ornaments...


--
Wally
www.art-gallery.myby.co.uk
Moving soon to: www.artbywally.com

On Tue, 13 Jan 2004 16:05:08 -0000, "Wally"
wrote:

Don Pearce wrote:

There was a design recommended by Wharfedale back in the sixties that
used a concrete drain pipe for exactly the purpose you describe. I'm
sure that with a little searching round the bigger plumbers you could
find something suitable.

I remember something like that (with the driver mounted in the side rather
than on the end). I'll be having a wander round the local DIY to check out
their audiophile-quality garden ornaments...

The Wharfedale design used the driver mounted vertically in the end of
the pipe, with a conical reflector suspended above it.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Tue, 13 Jan 2004 18:00:55 +0000 (UTC),
(Stewart Pinkerton) wrote:

On Tue, 13 Jan 2004 16:05:08 -0000, "Wally"
wrote:

Don Pearce wrote:

There was a design recommended by Wharfedale back in the sixties that
used a concrete drain pipe for exactly the purpose you describe. I'm
sure that with a little searching round the bigger plumbers you could
find something suitable.

I remember something like that (with the driver mounted in the side rather
than on the end). I'll be having a wander round the local DIY to check out
their audiophile-quality garden ornaments...

The Wharfedale design used the driver mounted vertically in the end of
the pipe, with a conical reflector suspended above it.

And didn't it use the Super 8 RSDD driver that got discussed to death
here recently?

d

_____________________________

http://www.pearce.uk.com

On Tue, 13 Jan 2004 18:00:55 +0000 (UTC),
(Stewart Pinkerton) wrote:

On Tue, 13 Jan 2004 16:05:08 -0000, "Wally"
wrote:

Don Pearce wrote:

There was a design recommended by Wharfedale back in the sixties that
used a concrete drain pipe for exactly the purpose you describe. I'm
sure that with a little searching round the bigger plumbers you could
find something suitable.

I remember something like that (with the driver mounted in the side rather
than on the end). I'll be having a wander round the local DIY to check out
their audiophile-quality garden ornaments...

The Wharfedale design used the driver mounted vertically in the end of
the pipe, with a conical reflector suspended above it.

And didn't it use the Super 8 RSDD driver that got discussed to death
here recently?

d

_____________________________

http://www.pearce.uk.com

Stewart Pinkerton wrote:

The Wharfedale design used the driver mounted vertically in the end of
the pipe, with a conical reflector suspended above it.

Maybe it wasn't the Wharfdale that I saw (a picture of). I do remember a
drainpipe jobbie with the driver in the side. Rogers, maybe?


--
Wally
www.art-gallery.myby.co.uk
Moving soon to: www.artbywally.com

Stewart Pinkerton wrote:

The Wharfedale design used the driver mounted vertically in the end of
the pipe, with a conical reflector suspended above it.

Maybe it wasn't the Wharfdale that I saw (a picture of). I do remember a
drainpipe jobbie with the driver in the side. Rogers, maybe?


--
Wally
www.art-gallery.myby.co.uk
Moving soon to: www.artbywally.com

On Tue, 13 Jan 2004 16:05:08 -0000, "Wally"
wrote:

Don Pearce wrote:

There was a design recommended by Wharfedale back in the sixties that
used a concrete drain pipe for exactly the purpose you describe. I'm
sure that with a little searching round the bigger plumbers you could
find something suitable.

I remember something like that (with the driver mounted in the side rather
than on the end). I'll be having a wander round the local DIY to check out
their audiophile-quality garden ornaments...

The Wharfedale design used the driver mounted vertically in the end of
the pipe, with a conical reflector suspended above it.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

"Wally" wrote:

: Don Pearce wrote:
:
: There was a design recommended by Wharfedale back in the sixties that
: used a concrete drain pipe for exactly the purpose you describe. I'm
: sure that with a little searching round the bigger plumbers you could
: find something suitable.
:
: I remember something like that (with the driver mounted in the side rather
: than on the end). I'll be having a wander round the local DIY to check out
: their audiophile-quality garden ornaments...

These look suitably horrible ...
http://www.cornu.de/en/tml.html

I'm sure I've seen similiar constructions elsewhere too.
I do suspect that just bunging anything other than a limited bandwidth sub
into a drainpipe is going to lead to all sorts of complex resonances.

Heavy math references:
http://www.quarter-wave.com/