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Columbia BS sound issue

Posted: Wed Jun 13, 2018 7:07 pm
by TinfoilPhono
I was not happy with the sound of my BS coin-op, even after Steve Medved's masterful restoration of the reproducer. I did some experimenting and tried taking off the cloth-covered tube between the reproducer and the horn mount and put an ordinary 10" horn in place. It sounded fantastic. Then I took a piece of plain rubber tubing over the caps of the connectors and played it through the proper horn. Perfection. So, obviously there is sound either leaking out through the original tubing, or it is somehow blocked.

I see nothing blocking the inside of the tube. It has a wire coil to allow it to bend, but that doesn't constrict it appreciably.

I tried putting an eartube connector on the carriage, and ran small diameter tubing inside the original cloth-covered tube. It sounded a little better than with just the original tube but still nowhere near as loud and clear as with the larger rubber tubing.

Has anyone run into this problem? I'm guessing that I'll have to somehow find rubber tubing of the correct ⅝" OD and use that in place of the original. Unless someone has a better idea...

Re: Columbia BS sound issue

Posted: Wed Jun 13, 2018 9:11 pm
by ChuckA
TinfoilPhono wrote:I was not happy with the sound of my BS coin-op, even after Steve Medved's masterful restoration of the reproducer. I did some experimenting and tried taking off the cloth-covered tube between the reproducer and the horn mount and put an ordinary 10" horn in place. It sounded fantastic. Then I took a piece of plain rubber tubing over the caps of the connectors and played it through the proper horn. Perfection. So, obviously there is sound either leaking out through the original tubing, or it is somehow blocked.

Has anyone run into this problem? I'm guessing that I'll have to somehow find rubber tubing of the correct ⅝" OD and use that in place of the original. Unless someone has a better idea...

I have the same problem with my AS, whatever the rubber like lining sealer used in the cloth is gone and air pressure leaks out through the cloth. I tried painting the inside with a liquid that was originally used to rejuvenate idler wheels on turntables, it helped a bit but I think I need to build it up with many layers and just haven't had the time.

Chuck

Re: Columbia BS sound issue

Posted: Thu Jun 14, 2018 1:53 am
by MTPhono
I have a similar issue (loss of volume) with my Amberola X linkage between reproducer and horn. Obviously not going to be fixed with glue but would be interested if there is a solution. I've never been able to solve it.

Re: Columbia BS sound issue

Posted: Thu Jun 14, 2018 11:11 am
by phonospud
Chuck is spot on. The rubber used on the inner surface of the cloth has disintegrated . When I make my reproductions, I incorporate a rubber membrane which makes my flexible joints for these machines air/sound tight.

Re: Columbia BS sound issue

Posted: Thu Jun 14, 2018 8:06 pm
by TinfoilPhono
At the PM-ed suggestion of a friend who is also a fellow forum member, I proceeded to line the inside of the tube with rubber cement to seal it. I put five coats in it, letting the cement dry in between. For the first two coats I used the supplied brush to spread it throughout the inside, and flexed it repeatedly to ensure that the rubber worked its way between the tight coils of the interior spring. For the last three coats I thought of a potentially more effective application -- I dripped a very large blob of cement into one end, tilted it downward at a 45 degree angle, and rotated it constantly as the blob slowly worked its way down. That ensured that the entire lining was well-coated. Once cement started to drip out the bottom end, I turned it over and continued to rotate it as it flowed back in the other direction. It only takes a few minutes until it's set up firm enough to no longer drip, and leaves a relatively heavy coating.

After three such heavy applications I felt confident that it was thoroughly lined and that no air / sound could escape. Once it was dry I put it back on the machine and tested it.

WOW! Now it is loud. It's a night and day difference. I only wish I had made a before and after video to demonstrate just how dramatic that difference actually is.

Rubber cement essentially creates a brand-new rubber tube inside the old cloth-covered tube, and it remains completely flexible. So a reasonably quick, easy, and extremely effective solution to a vexing problem.

Re: Columbia BS sound issue

Posted: Thu Jun 14, 2018 11:24 pm
by phonogfp
An interesting fix - thanks for sharing this. I tested my BS after reading your original post, and there is a slight loss of volume when using the cloth/wire tube. Maybe I'll try your technique.

George P.

Re: Columbia BS sound issue

Posted: Fri Jun 15, 2018 8:51 am
by phonospud
Excellent idea! I’ve not tried to improve original examples for fear of visual damage. Glad to hear it works !

Re: Columbia BS sound issue

Posted: Fri Jun 15, 2018 9:08 am
by HisMastersVoice
Liquid latex would also work great for this, in fact it’s a bit thinner than rubber cement so it may actually be easier to work with and coat the inside more evenly.

Re: Columbia BS sound issue

Posted: Fri Jun 15, 2018 9:32 am
by melvind
I picked up a Columbia AS at Union and it plays well but softly. What great timing for me. I may be looking into a coating to improve the volume as well.

Re: Columbia BS sound issue

Posted: Fri Jun 15, 2018 9:39 am
by TinfoilPhono
HisMastersVoice wrote:Liquid latex would also work great for this, in fact it’s a bit thinner than rubber cement so it may actually be easier to work with and coat the inside more evenly.
I've never worked with that but the one potential concern I might have is if it's too thin, it might creep through the spring coils and stain the cloth wrapping. I was concerned about keeping that unscathed so I did only a small test patch at first, inside the end which is covered by a piece of metal tubing. There was no soak-through so I went ahead with the project.

I'm really happy with the outcome! It works great and is an invisible fix.