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 Post subject: Aluminium vs mica diaphragms
PostPosted: Thu Mar 22, 2018 5:55 pm 
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Victor Jr
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Hello, I'm very happy to have joined this forum, you're all incredibly resourceful! I'm pretty new to gramophones, but had recently got myself a Columbia Viva Tonal 112. It's fantastic and I'm very happy with it. So far, I've regreased the motor (without disassembling it, don't feel confident enough yet. I also can't figure out how to remove the crank, it doesn't budge any way I tried), and replaced the hardened rubber gaskets.
The reproducer has an aluminium diaphragm, and I've been reading a lot about people replacing them with mica diaphragms. Would anyone help a new collector out, and explain me the difference between those two in terms of the sound they produce? I'm wondering if it would help with sound clarity and would eliminate the occasional buzzing with louder records?
Thank you all very much! I'm looking forward to learning from all of you.


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 Post subject: Re: Aluminium vs mica diaphragms
PostPosted: Thu Mar 22, 2018 7:32 pm 
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Victor II
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I wouldn't change the diaphragm (unless there's something major wrong with it).Mica diaphragms can sound very good, but I think this reproducer was designed to use the then-new aluminum diaphragms and they really play electrically recorded records very well. I think the main things to do are:
1) Replace gaskets. You said you already did this, and they might be fine, but all gaskets are not created equal. You can experiment with different materials and sizes. I recommend medium soft silicone rubber or natural rubber. I haven't owned a viva tonal in a while so I don't know the size of tubing you would need.
2) Make sure the pivots are just holding the needle bar steady and not rattling but not overly-tight. Tiny drop of oil on each side may help.
3) Get/make a new rubber flange for the back fitting. I did this long ago, but it's a little tricky. I think I got some sheet rubber and just cut it out using the old dry one as a pattern, punching holes where the screws needed to go. It's essential not to mess with this unless you get the material and know you can do it, because if you are without that thin gasket on the back, the reproducer is useless.

Sorry I'm not very detailed, I can't remember what I did exactly. I do remember it sounded great, and mine was a portable model too.
"There are two kinds of people in this world: people who eat grapes in the grocery store and good people."


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 Post subject: Re: Aluminium vs mica diaphragms
PostPosted: Thu Mar 22, 2018 7:45 pm 
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Victor IV
Joined: Sat Jul 09, 2016 7:12 pm
Posts: 1534
I second JWB's comments.

Mica diaphragms were commonly used in gramophones produced during the 1890s through about 1930, though after 1925, aluminum became the preferred material. The Columbia "Viva-Tonal" series was specifically designed to play the newly introduced electrically recorded records, which hit the market in 1925, with greater fidelity than the earlier models.

This shows the capability of a well-restored 112 -- https://www.youtube.com/watch?v=0WBnNYz3AuE

Replacing the more flexible aluminum diaphragm with a mica diaphragm will be a step backwards, in terms of sound quality.

Here's a good primer on the history of recording processes -- https://en.wikipedia.org/wiki/History_o ... _recording



OrthoFan


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 Post subject: Re: Aluminium vs mica diaphragms
PostPosted: Fri Mar 23, 2018 6:48 am 
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Victor Jr
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Jwb88 wrote:
I wouldn't change the diaphragm (unless there's something major wrong with it).Mica diaphragms can sound very good, but I think this reproducer was designed to use the then-new aluminum diaphragms and they really play electrically recorded records very well. I think the main things to do are:
1) Replace gaskets. You said you already did this, and they might be fine, but all gaskets are not created equal. You can experiment with different materials and sizes. I recommend medium soft silicone rubber or natural rubber. I haven't owned a viva tonal in a while so I don't know the size of tubing you would need.
2) Make sure the pivots are just holding the needle bar steady and not rattling but not overly-tight. Tiny drop of oil on each side may help.
3) Get/make a new rubber flange for the back fitting. I did this long ago, but it's a little tricky. I think I got some sheet rubber and just cut it out using the old dry one as a pattern, punching holes where the screws needed to go. It's essential not to mess with this unless you get the material and know you can do it, because if you are without that thin gasket on the back, the reproducer is useless.

Sorry I'm not very detailed, I can't remember what I did exactly. I do remember it sounded great, and mine was a portable model too.


Thank you very much! The rubber flange is the one thing I haven't changed yet, it has hardened, too. I think I'll get a piece of rubber and make one.


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 Post subject: Re: Aluminium vs mica diaphragms
PostPosted: Fri Mar 23, 2018 6:49 am 
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Victor Jr
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Joined: Mon Mar 19, 2018 7:53 pm
Posts: 15
Location: France
OrthoFan wrote:
I second JWB's comments.

Mica diaphragms were commonly used in gramophones produced during the 1890s through about 1930, though after 1925, aluminum became the preferred material. The Columbia "Viva-Tonal" series was specifically designed to play the newly introduced electrically recorded records, which hit the market in 1925, with greater fidelity than the earlier models.

This shows the capability of a well-restored 112 -- https://www.youtube.com/watch?v=0WBnNYz3AuE

Replacing the more flexible aluminum diaphragm with a mica diaphragm will be a step backwards, in terms of sound quality.

Here's a good primer on the history of recording processes -- https://en.wikipedia.org/wiki/History_o ... _recording



OrthoFan


This is exactly what I wanted to know, thank you. The aluminium diaphragm is fine, then.


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 Post subject: Re: Aluminium vs mica diaphragms
PostPosted: Fri Mar 23, 2018 7:08 am 
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Victor IV
Joined: Wed Jan 07, 2009 8:44 pm
Posts: 1520
The only issue I find with my Columbia 800 is that some records tend to bring out a metallic sound on some very high notes. That from what I have researched seemed to be a common complaint about aluminum when it came out. However in comparison to mica it generally has a wider sound range and like said, works very well on good early electrical recordings without the sort of harsh bast the mica can produce. I do have a telefunken late portable which uses mica and its got amazing sound, but the same problems can show up on it.


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 Post subject: Re: Aluminium vs mica diaphragms
PostPosted: Fri Mar 23, 2018 10:52 am 
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Victor III
Joined: Sun May 27, 2012 2:38 pm
Posts: 753
Location: United Kingdom
Ermm, as the crank goes through the hole on the front of the case, then straight into the motor, I'm intrigued as to how you managed to get the motor out, if you can't remove the crank?


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 Post subject: Re: Aluminium vs mica diaphragms
PostPosted: Fri Mar 23, 2018 11:01 am 
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Victor III
Joined: Sun May 27, 2012 2:38 pm
Posts: 753
Location: United Kingdom
GabrielePfr wrote:
Thank you very much! The rubber flange is the one thing I haven't changed yet, it has hardened, too. I think I'll get a piece of rubber and make one.


Not that easy, I'm afraid. The holes are not of uniform diameter all the way through. The lower half has to receive the main shank of the fixing screw, and the upper half has to take the head of the screw.The only way would be to make two separate gaskets and glue them together, but everything has to be very accurate, or nothing will line up.


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 Post subject: Re: Aluminium vs mica diaphragms
PostPosted: Fri Mar 23, 2018 11:56 am 
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Victor Jr
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Phono48 wrote:
Ermm, as the crank goes through the hole on the front of the case, then straight into the motor, I'm intrigued as to how you managed to get the motor out, if you can't remove the crank?


I unscrewed the round plate that holds the crank in place, and lifted the motor enough that I could get to it. I did not disassemble it, the grease was still good, I only applied some oil to the bearings and such, and grease to the gears. I know this is not the proper way of doing it, so this is only for the time being, until I am able to remove the motor from the case and reassemble it. The regreasing helped with the noise, so that will do for now.


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 Post subject: Re: Aluminium vs mica diaphragms
PostPosted: Fri Mar 23, 2018 12:00 pm 
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Victor Jr
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Joined: Mon Mar 19, 2018 7:53 pm
Posts: 15
Location: France
Phono48 wrote:
GabrielePfr wrote:
Thank you very much! The rubber flange is the one thing I haven't changed yet, it has hardened, too. I think I'll get a piece of rubber and make one.


Not that easy, I'm afraid. The holes are not of uniform diameter all the way through. The lower half has to receive the main shank of the fixing screw, and the upper half has to take the head of the screw.The only way would be to make two separate gaskets and glue them together, but everything has to be very accurate, or nothing will line up.


Interesting. When I took it off it looked like a regular o ring, pretty uniform. I'll take a closer look at it when disassembling next time.


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