18 August 2011

Project "His Master's Voice Soundbox No.5B"






the current soundbox/reproducer i have on my gramophone was bought on ebay from india and it arrived in pretty bad shape. for starters, the diaphragm had a hole in it and the rubber connector crumbled into dust when i fitted it on to the tonearm.

i scrounged the world (online) for spare parts and managed to get a new rubber connector a few months ago but i had no luck with finding a replacement diaphragm...UNTIL LAST WEEK!!

i would like to say a big thank you to Mr. Ken Priestley of the U.K for his expertise. i managed to find a new diaphragm from him and those of you looking for spare parts for your gramophone can look for him at his website: http://www.fonograf.talktalk.net/

anyway i ordered a new diaphragm from him last week and it arrived here in singapore within 8 days (as fast as international mail gets around these parts).






he packed it really nicely with cardboard spacer preventing the diaphragm from warping/tearing.

anyway...if you are interested to do a diaphragm replacement on a HMV 5b soundbox, this is how i did it:






unscrew all four screws on the back of the soundbox and the rear (black) plate comes right off. in the picture above, you can see the felt gasket that is fitted around the edges of the diaphragm to make it more airtight. you can see the lousy repair job i did on my old diaphragm...i basically glued aluminum foil around the hole to patch it up!





remove the four screws on the front plate of the soundbox. use a pair of pliers to hold the nut on the needle bar and gently unscrew the pivot screw (both of them). at this point the diaphragm and the needle bar can be gingerly removed from what's left of the soundbox.






you should then be left with just the diaphragm and needle bar as shown in the picture above. the needle bar on mine was soldered on to the spider. you will obviously need a soldering iron to melt the solder, so be extra careful during this step! i put a small precision screwdriver to hold the diaphragm in place as i desoldered the needle bar from the spider like so:







look at the difference in condition between my old tattered diaphragm as compared to the new one, no prizes for guessing which is which!







i soldered the needle bar on to the new diaphragm, making sure to position it in the center of the spider. the soundbox can now be reassembled by working backwards from the steps shown above. if you find the needle bar is out of position after fitting the diaphragm into the soundbox, it can be repositioned by simply touching the soldering iron to the solder and small adjustments can then be made.








i fitted the soundbox back on to the gramophone and played a few records. one of the obvious improvements i noticed straightaway was the increase in volume and overall fullness of the music, no more wasted energy due to air leaks! voices were clearer, strings were cleaner...its a pity i couldn't have gotten a perfect diaphragm sooner, but i'm very happy that i finally do!


7 comments:

  1. Hi! P,
    The diaphragm which u got it from Ken, is mend for the 5A HMV Soundbox.
    It must be very costly for u!
    Does he not have any diaphragm for the 5B model?
    I used to deal with him. And he is a friendly & helpful guy.
    I have undertake the same project as u do in the past.
    Do u change the pair of gaskets? Don't used the old ones. U may keep them.
    I have tried changing the followings on my Soundbox as well:-
    1. Rubber bushing for the tone arm connector.
    2. The pair of gasket.
    3. Replace the old stiff stylus needle bar (which is often rusty).
    4. Try looking for the correct diaphragm. And is going to cost me alot which I find not worth it on ebay. Instead salvage from another old soundbox.
    U collect gramophone as well?
    I can be reach at sengchee.chia@pacific.net.sg
    & we can discuss more about it.
    Thanks!
    Rgds,
    Chee

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  2. i have replied to your email, nice to hear from someone interested in gramophones too!

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  3. First let me say I am most impressed with your repair.

    The damaged diaphragm is the one found in the US Victor Orthophonic and the 5A normally. The one with the triangle design was made by HMV and is normally found in the 5B. Sound wise there is not a difference.

    Victor used paper gaskets coated with what looks like varnish, HMV used felt gaskets which sound bad. The diaphragm was designed to be clamped firmly in place. Replacing the felt with neoprene rubber vastly improves the sound. I have 5A's, 5B's, and the regular Victor Orthophonic and suitcase models with the cover on the front.

    The other difference between the Victor 5 and the HMV 5's is the needle bar pivot design on the HMV is far easier to work on. On the No 4 and No 5 make sure the needle bar moves freely, I had one No 4 the one pivot was slightly over sized and the bar did not move freely and the sound was poor.

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  4. sorry for the late reply i didn't get a notification! anyway thanks a lot for your comment and pointing out the difference between a 5A and a 5B diaphragm too, i've learnt something new!

    i am currently using the same felt gaskets, i have yet to find suitable neoprene replacement gaskets. i still play my gramophone every now and then and it still sounds great. it is definitely a piece of history to be kept, i just hope that when it inevitably (as will all machines) breaks down there will still be replacement parts available..it took me a long time just to find a good replacement diaphragm!

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  5. Hi I need diaphragm for my gramaphone.Where do you offer me to buy it from?

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    Replies
    1. hello, i stated in the post above that i bought the diaphragm from Ken Priestley in the U.K, you can find his contact details at his website http://www.fonograf.talktalk.net/

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  6. Dear sir,I have columbia box granaphone.my sound box not working.I need to replace new diaphragm for my sound box.please help me yo do it.

    ReplyDelete