Needle length

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Daithi
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Re: Needle length

Post by Daithi »

I have seen your adapter in another post. It was very inspiring.
The baĺl joint connector is fully adjustable to any angle Inigo.
Its part of an aquarium nozzle which can be found on Ebay for a few euro.
Here is a link
https://www.ebay.ie/itm/Aquarium-Pump-D ... 5464151888?

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Inigo
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Re: Needle length

Post by Inigo »

Thanks..
Although it seems to impose a strangulation in the sound path... Or is it only the external appearance?
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Orchorsol
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Re: Needle length

Post by Orchorsol »

Inigo wrote: Wed Nov 02, 2022 8:45 am Thanks..
Although it seems to impose a strangulation in the sound path... Or is it only the external appearance?
Interesting... so does the "phase plug" in HMV 5A/5B soundboxes!
BCN thorn needles made to the original 1920s specifications: http://www.burmesecolourneedles.com

Youtube channel: https://www.youtube.com/channel/UCe4DNb ... TPE-zTAJGg?

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Inigo
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Re: Needle length

Post by Inigo »

Yes but no. The phase plug in its refined version (the first one) is like a bullet pointing out of the soundbox neck. It is intended to take sir vibrations from the perimeter of the diaphragm, adding an obstacle to the ones coming directly from the center. Theoretically this is intended to produce an even sound wavefront coming out from the neck, because the vibrations from different parts of the soundbox chamber are not in phase, and mixing them incoherently would cancel some of them, there ones with shorter wavelength, which get reflected inside the sound chamber, etc...
They later suppressed the central bullet.
This part, in HMV soundboxes, was made from pot metal foundry, and used to have imperfections and small burrs that partially obliterated the circular vents around the bullet. At least mine were so. I polished the holes contours and the profiles of the small bars around the bullet, and removed the burrs with a very sharp file. I don't know if it makes much difference in the final sound, but I can tell you that I'm still waiting to listen to any soundbox which sounds better than my old tuned HMV 5a.
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Marco Gilardetti
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Re: Needle length

Post by Marco Gilardetti »

Inigo wrote: Wed Nov 02, 2022 10:19 am I polished the holes contours and the profiles of the small bars around the bullet, and removed the burrs with a very sharp file.
[...]
They later suppressed the central bullet.
I remeber you mentioned this filing work in a past thread. When did they suppressed the waveguide bullet? Do you mean that there are 5A/5Bs that were natively made without, or did they suppressed it in subsequent models?

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Inigo
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Re: Needle length

Post by Inigo »

I've got only three of these soundboxes, old golden 5a, then two Chrome 5a and 5b. All them have the bullet. Even one Indian copy I had (now broken, because it's made of poor metal) also had the bullet.
I know by photos that later models of EMI soundboxes didn't have the bullet, only a plain three leg spider without the central bullet. I've seen also other soundboxes (Thorens and Paillard) that have also the spider, or a metal grid... I know also that later Victor/RCA soundboxes also abandoned the bullet.
The grid must have a similar effect. It reminds me of the bees nest they added early in 1900 to certain Exhibition soundboxes, kind of a cylinder made of light narrow pipes that was installed in the neck outlet. I have seen it advertised as an accessory to be added to improve the sound. It seemed like a bunch of drinking canes, maybe an inch long.
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Daithi
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Re: Needle length

Post by Daithi »

The constriction is external Inigo. The narrowest part of the sound path is about the same diameter as an HMV swan neck. The large exterior diameters are to accomodate the mounting flange and the ball joint.

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Inigo
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Re: Needle length

Post by Inigo »

Thanks, that's fine then... I have to look at my local hardware mart to see if I find something similar... The good thing when buying locally is that you can take a tonearm with you and try it directly at the shop.
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Marco Gilardetti
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Re: Needle length

Post by Marco Gilardetti »

Inigo wrote: Mon Nov 07, 2022 4:31 amIt reminds me of the bees nest they added early in 1900 to certain Exhibition soundboxes, kind of a cylinder made of light narrow pipes that was installed in the neck outlet. I have seen it advertised as an accessory to be added to improve the sound. It seemed like a bunch of drinking canes, maybe an inch long.
Yes, in turn I remember also this thread. It is beyond my imagination to understand to which avail this gizmo is aimed to. If the purpose was to re-align the wavefront, I don't think it will work: each "drinking cane" will trigger a wave travelling through its body each time its opened edge (throat) is stimulated by the waves inside the soundbox chamber. If these waves happen to have an irregular wavefront, each drinking cane throat will be hit at a slightly different time, and as the wave will travel at the same speed through each cane, the same time lag will show up at the cane's mouth at the other side.

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alang
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Re: Needle length

Post by alang »

Inigo wrote: Mon Nov 07, 2022 4:31 am
The grid must have a similar effect. It reminds me of the bees nest they added early in 1900 to certain Exhibition soundboxes, kind of a cylinder made of light narrow pipes that was installed in the neck outlet. I have seen it advertised as an accessory to be added to improve the sound. It seemed like a bunch of drinking canes, maybe an inch long.
I think you're talking about the Morse Clarifier. It's been discussed here viewtopic.php?t=5926. Unfortunately, the picture are gone.

Andreas

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