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 Post subject: Re: DIY soundbox / reproducer diaphragm - any tips ?
PostPosted: Wed Jan 29, 2020 4:42 pm 
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Victor IV
Joined: Sun Jul 08, 2012 1:06 pm
Posts: 1533
The late great Bob Waltrip developed diaphragms from the thin stiff styrofoam used in grocery store meat trays. The results were quite good. Most of them were used for diamond disc reproducers but I think he did some on others with equally positive results.


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 Post subject: Re: DIY soundbox / reproducer diaphragm - any tips ?
PostPosted: Wed Jan 29, 2020 5:42 pm 
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Victor IV
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Location: Dover, UK
If I recall corectly, the late Douglas Fitzpatrick ( viewtopic.php?f=11&t=32807 ) used a plastic diaphragm from a stethoscope in an Expert or EMG soundbox, installed with different types of gasket each side of the diaphragm.
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 Post subject: Re: DIY soundbox / reproducer diaphragm - any tips ?
PostPosted: Wed Jan 29, 2020 7:34 pm 
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Victor II
Joined: Wed Dec 04, 2019 9:31 pm
Posts: 220
I tried coke cans, food containers like coleslaw tubs, made of various plasics. Plastic milk bottles. I think flat materials are not compliant enough even though they can be made to produce good sound. I think the corrugations in commercial diaphragms are important for compliance, so in the end I just bought one on ebay. I think the suggestion by audioengr above about using the diaphragm from an electric speaker is very interesting. So I want to try that now.


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 Post subject: Re: DIY soundbox / reproducer diaphragm - any tips ?
PostPosted: Thu Jan 30, 2020 12:35 pm 
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Victor IV
Joined: Wed May 20, 2009 8:20 pm
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Location: Mid - Michigan
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 Post subject: Re: DIY soundbox / reproducer diaphragm - any tips ?
PostPosted: Thu Jan 30, 2020 7:08 pm 
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Victor II
Joined: Wed Dec 04, 2019 9:31 pm
Posts: 220
A diaphragm should be stiff in the center and flexible near the edges. It can push more air that way. Is that why they call it volume?


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 Post subject: Re: DIY soundbox / reproducer diaphragm - any tips ?
PostPosted: Thu Jun 11, 2020 1:40 pm 
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Victor O
Joined: Fri Mar 17, 2017 2:52 pm
Posts: 54
Location: Chicago
PeterF wrote:
The late great Bob Waltrip developed diaphragms from the thin stiff styrofoam used in grocery store meat trays. The results were quite good. Most of them were used for diamond disc reproducers but I think he did some on others with equally positive results.


I remember someone telling me (probably a good 20-25 years ago) that Bob Waltrip also used plastic milk jug material, but I may be misremembering this.


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 Post subject: Re: DIY soundbox / reproducer diaphragm - any tips ?
PostPosted: Sun Aug 30, 2020 6:50 pm 
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Victor Jr
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Posts: 43
Location: The south of England
shoshani wrote:
I remember someone telling me (probably a good 20-25 years ago) that Bob Waltrip also used plastic milk jug material, but I may be misremembering this.


I've experimented with plastic milk bottle material recently (HDPE) and also Polystyrene from a CD jewel case and a 3D printed PLA diaphragm too. I have also been experimenting with 3D printed sound boxes/reproducers

I've made some videos on YouTube if anybody is interested in the results :D

https://youtu.be/XqAlJVpN3ZM
https://youtu.be/kh-0SHxQbmY
https://youtu.be/pw9DoCmvl9s
https://youtu.be/gCv5-lAIjvw

I have also made some metal diaphragms which I will compare in a video shortly and I have a mica diaphragm on order so I can see how that compares too! ;)


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 Post subject: Re: DIY soundbox / reproducer diaphragm - any tips ?
PostPosted: Mon Aug 31, 2020 3:01 am 
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Victor III
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mrrgstuff wrote:
shoshani wrote:
I remember someone telling me (probably a good 20-25 years ago) that Bob Waltrip also used plastic milk jug material, but I may be misremembering this.


I've experimented with plastic milk bottle material recently (HDPE) and also Polystyrene from a CD jewel case and a 3D printed PLA diaphragm too. I have also been experimenting with 3D printed sound boxes/reproducers

I've made some videos on YouTube if anybody is interested in the results :D

https://youtu.be/XqAlJVpN3ZM
https://youtu.be/kh-0SHxQbmY
https://youtu.be/pw9DoCmvl9s
https://youtu.be/gCv5-lAIjvw

I have also made some metal diaphragms which I will compare in a video shortly and I have a mica diaphragm on order so I can see how that compares too! ;)


Absolutely fantastic ! I haven't seen all your video's yet but look forward to seeing them fully tonight.

How much do your blue soundboxes cost approximately to print / make I wonder ? Could they start to be sold ?

Such interesting videos too !
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 Post subject: Re: DIY soundbox / reproducer diaphragm - any tips ?
PostPosted: Mon Aug 31, 2020 12:21 pm 
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Victor IV
Joined: Sat Jul 09, 2016 7:12 pm
Posts: 1709
mrrgstuff wrote:
shoshani wrote:
I remember someone telling me (probably a good 20-25 years ago) that Bob Waltrip also used plastic milk jug material, but I may be misremembering this.


I've experimented with plastic milk bottle material recently (HDPE) and also Polystyrene from a CD jewel case and a 3D printed PLA diaphragm too. I have also been experimenting with 3D printed sound boxes/reproducers

I've made some videos on YouTube if anybody is interested in the results :D

https://youtu.be/XqAlJVpN3ZM
https://youtu.be/kh-0SHxQbmY
https://youtu.be/pw9DoCmvl9s
https://youtu.be/gCv5-lAIjvw

I have also made some metal diaphragms which I will compare in a video shortly and I have a mica diaphragm on order so I can see how that compares too! ;)


The videos are VERY interesting, and I especially like the idea of the 3-D printed sound box. Listening to the various diaphragms, I noticed the the upper register notes, in most cases, are dampened. One thing you might consider is redesigning the needle bar to accommodate a much smaller diaphragm connector-screw--one that is similar in size to the ones used on HMV, Columbia, etc. sound boxes. If the screw and bolt is too massive, it will impact the needle bar's ability to transfer the higher frequency vibrations from the needle's tip to the diaphragm--or so I have been told by a couple of restorers. Likewise, for diaphragms attached using solder, only a "whisper" of solder should be applied.

Case in point: I used to have an HMV #5b sound box that was repaired with a diaphragm culled from an earlier model HMV 5a. I noticed that the upper notes seemed to be dampened compared to my Orthophonic sound box, and there was annoying "burping" noise made when bass notes were played. Upon inspection, I saw that the repairman had applied a bead of solder about the size of a small pea to connect the needle bar to the spider. I eventually had the sound box re-repaired, with the proper amount of solder applied, and the difference was like night and day--crisp treble, solid mid-range, and excellent bass, with no distortion.

OrthoFan


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 Post subject: Re: DIY soundbox / reproducer diaphragm - any tips ?
PostPosted: Mon Aug 31, 2020 2:38 pm 
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Victor IV
Joined: Sun Mar 15, 2009 6:18 am
Posts: 1158
Location: Luxembourg
Very interesting and well done video!

May I suggest to add in the playing comparison one industrial soundbox like the 5a/b that is lying on the gramophone. It would serve as common reference to all the new developments.


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