Tannoy Pepperpot

[radiosmuck]

Hi,
I have just been looking at an image of the Tannoy Westminster Royal "pepperpot" and there looks to be nothing much left after the holes have been drilled.
What is the advantage of the "pepperpot" over a large bored conical throat?
Thanks

An externally hosted image should be here but it was not working when we last tested it.

 

[weltersys]

Hi,
I have just been looking at an image of the Tannoy Westminster Royal "pepperpot" and there looks to be nothing much left after the holes have been drilled.
What is the advantage of the "pepperpot" over a large bored conical throat?

A large bored throat would have the effect of the output of the edge of the diaphragm traveling a longer distance than the center, causing HF cancellation and peaky response.

The "Pepperpot" holes are at angles going to the diaphragm, a primitive "phase plug".

Most (good) phase plugs for round diaphragms are now done with annular slits, which work better than drilled holes, but require more advanced machining than a drill press.

 

[Charles Darwin]

The function is as weltersys describes.

At some point Tannoy replaced the pepperpot with the tulip waveguide.
Technically the tulip is superior as it does away with the need of a notch filter in the crossover (although I'm not sure if the modern pepperpots still need it) and the treble is better controlled, less ragged and more extended.
That said the main reason for Tannoy to replace the pepperpot was its huge manufacturing cost compared to the tulip wave guide as it is basically a cheap to make concoction of plastic and pressed steel.

About ten years after its deletion the pepperpot was re-introduced in Tannoys Prestige range after pressure from well-to-do Tannerds along with AlNiCo V magnets.
In the end I think a fair percentage of Tannoy pepperpot buyers buy them for the same reasons others buy a Breguet watch rather than a Casio.

 

[adason]

"...and there looks to be nothing much left after the holes have been drilled.
What is the advantage of the "pepperpot" over a large bored conical throat?"

it only looks that way from the front, the holes spread back...

 

[adason]

like this...

 

[Pallas]

What is the advantage of the "pepperpot" over a large bored conical throat?
Thanks

An externally hosted image should be here but it was not working when we last tested it.

It's a rudimentary phase plug. The modern Tannoy "Tulip" is a superior phase plug.

 

[Pallas]

For anyone interested, Soundstage managed to get measurements of the new Tannoy DC10A, a retro-fetishist part with the antiquated Pepperpot phase plug and an obsolete magnet system.

SoundStageNetwork.com | SoundStage.com | NRC Measurements: Tannoy Definition DC10A Loudspeakers

I presume their parts with their modern phase plug and current-technology magnets do better. Their parts of 10-15 years ago certainly did. The alternative is that Tannoy has lost the ability to competently design a loudspeaker, which I really hope isn't the case!

 

[Face]

That blip @ 700hz is probably a surround resonance.

 

[Charles Darwin]

It's unlikely that it's the tweeter since the crossover frequency of the DC10A is 1.1kHz.

 

[Pallas]

The whole thing is just awful-looking, not just the 700Hz stuff.

But the type of people who would buy it probably don't care. "Use your ears," or some such nonsense is the refrain.