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B.R.O.S. Sound-box disussion (Continued)

Posted: Wed Jul 03, 2024 4:26 pm
by poodling around
Discussion transfered from:

viewtopic.php?f=14&t=58349&start=20

Post by leels1 » Wed Jul 03, 2024 6:35 pm
This is the BROS. Is yours similar?



Wow ! Yours is in much better condition than mine. Yours looks nearly new !

This is mine - showing how large it is - 3 inches about.

Mine either doesn't have the screw near the 'chuck' or it has broken off.

Do you know what that screw does I wonder ?

Re: B.R.O.S. Sound-box disussion (Continued)

Posted: Thu Jul 04, 2024 4:13 pm
by leels1
It wasn’t like that when I got it! It needed a clean and new gaskets as they were rock hard.

I can’t remember what the screw was for, I’ll have to get it out again and check it.

Also not sure if the benefit of such a large diaphragm, I don’t think it adds any benefit to the sound reproduction.

Re: B.R.O.S. Sound-box disussion (Continued)

Posted: Sun Jul 07, 2024 3:40 pm
by poodling around
leels1 wrote: Thu Jul 04, 2024 4:13 pm It wasn’t like that when I got it! It needed a clean and new gaskets as they were rock hard.

I can’t remember what the screw was for, I’ll have to get it out again and check it.

Also not sure if the benefit of such a large diaphragm, I don’t think it adds any benefit to the sound reproduction.
Well, you certainly cleaned it up very well !

If you find yours again I would be interested to know if yours has three very different 'screw variations' on the 'reverse side' like mine.

Strangely mine is one of the best sounding sound-boxes I have.

Re: B.R.O.S. Sound-box disussion (Continued)

Posted: Wed Jul 10, 2024 7:25 am
by leels1
Hi, this is the reverse of mine. All the screws look the same so I wonder if on yours some of them may have been replaced at one time. I have a similar Pianina soundbox that has several types of flathead screw holding the back on.

The screw on the needle bar. I think if you unscrew that, it allows the vertical part of the needle bar to slide off the mounting plate so it can fit exactly to the hole in the diaphragm as the two screws that fit into the main body are tightened up.

Re: B.R.O.S. Sound-box disussion (Continued)

Posted: Wed Jul 10, 2024 12:47 pm
by poodling around
leels1 wrote: Wed Jul 10, 2024 7:25 am Hi, this is the reverse of mine. All the screws look the same so I wonder if on yours some of them may have been replaced at one time. I have a similar Pianina soundbox that has several types of flathead screw holding the back on.

The screw on the needle bar. I think if you unscrew that, it allows the vertical part of the needle bar to slide off the mounting plate so it can fit exactly to the hole in the diaphragm as the two screws that fit into the main body are tightened up.
Thank you - that is REALLY interesting !

As you can see from my photograph below, the three screws near the centre seem to have been replaced. One has three 'nuts' one has on nut' and the other has none. It seems that the person who did it didnt have the correct screw-driver so some of the screws have been badly damaged. However, as I say, this does sound very good so maybe s/he did something right ha ha ! It is really great to see yours though and how it was originally made.

Thank you also for explaining what the screw on the needle bar does.

Oh, did you say 'Pianina' ? I have one too ! Is yours the same as mine I wonder (Photograph 'below). It does resemble the B.R.O.S as you say !

Re: B.R.O.S. Sound-box disussion (Continued)

Posted: Fri Jul 12, 2024 1:47 pm
by leels1
Yep that’s the one! It’s also a decent sound.

I have a very similar one but as you can see it’s branded Larynx Rifanco but everything else about it is the same. It’s also similar to a large style Astra I have. They must have been made to a similar design.

Re: B.R.O.S. Sound-box disussion (Continued)

Posted: Sat Jul 13, 2024 1:33 pm
by drh
leels1 wrote: Thu Jul 04, 2024 4:13 pmAlso not sure if the benefit of such a large diaphragm, I don’t think it adds any benefit to the sound reproduction.
For whatever it's worth, that's the same size as the Pathé disc reproducer.

Re: B.R.O.S. Sound-box disussion (Continued)

Posted: Thu Jul 18, 2024 2:28 pm
by leels1
drh wrote: Sat Jul 13, 2024 1:33 pm
leels1 wrote: Thu Jul 04, 2024 4:13 pmAlso not sure if the benefit of such a large diaphragm, I don’t think it adds any benefit to the sound reproduction.
For whatever it's worth, that's the same size as the Pathé disc reproducer.
The Pathé soundboxes I have are a lot smaller. About 2” diaphragm diameter. They are the ones that are for a regular tone arm, with the elbow to adapt to fit the soundbox.

Re: B.R.O.S. Sound-box disussion (Continued)

Posted: Thu Jul 18, 2024 10:19 pm
by drh
leels1 wrote: Thu Jul 18, 2024 2:28 pm
drh wrote: Sat Jul 13, 2024 1:33 pm
leels1 wrote: Thu Jul 04, 2024 4:13 pmAlso not sure if the benefit of such a large diaphragm, I don’t think it adds any benefit to the sound reproduction.
For whatever it's worth, that's the same size as the Pathé disc reproducer.
The Pathé soundboxes I have are a lot smaller. About 2” diaphragm diameter. They are the ones that are for a regular tone arm, with the elbow to adapt to fit the soundbox.
I'd guess they must be late, or at least later. The type in my photos was Pathé's standard issue for open horn and US upright players for the sapphire ball records. It got some design modifications to the needle bar support over the years, and the very early ones had ebonite back plates, but the size, as far as I know, remained the same.