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Sony apm-77w woofer fix (I did it...kinda)

beezlebubba

Chicken Choker
:thmbsp:
ok so I have owned my sony apm-77w's since 84' or so. born in 1970 I guess I was really lucky to get my hands on these speakers which were given to my father at some electronic show he was helping hauling and carting for. I took them over as soon as he brought them into the house with their matching rolling metal stands sans grills. I rocked them through high school and beyond and they sufferred the inevitable fate of these...woofer disintegration. with their 4 magnet design they still functioned admirably albeit lacking some lower end extension and detail. We have rocked these at our piano shop for almost 15 years now and They see their share of rap and hiphop as well as jazz/fusion to whatever else. I was perusing ebay and saw a single kicker L5 blown sub for sale and asked him for the surround dimensions and was told they were almost exactly what I needed for my Sony's. With his reply he responded that if all I needed were the surrounds he could send me 2 for $20 shipped. a few days later I had the woofers out and was gluing the stiffer rubber surround on with player piano plastic glue. I decided to go with this flexible, durable glue because I have some experience using it and I had plenty below my bench in the shop. Its been about 2-3 weeks now and I must say that this is the best these speakers have sounded in 10 years and although not the prettiest repair it was fast and effective and it seems as if the surrounds are slowing breaking in and sounding better daily. for 25 year old square aluminum honeycomb 3 way speakers these sound rather neutral and revealing and still astound me to this day. I am now thinking of putting a surround system together with these as my mains but it is not so easy to find remaining pairs in this line-up. I did just manage to score a new in box tweeter on ebay from a apm-66es which I plan to use in a custom MTM center channel I will piece together in time. any help with sony apm speaker pairs, singles or drivers would be much appreciated. thanks again
 
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yes I am sure sound has changed from its original. like I said we have been using these speakers WITHOUT surrounds at all for 10 years now and they sounded fine with a cambridge soundworks powered subwoofer handling most of the lower end. I have see the Japanese APM site with the chamois and starch surround fix. I will probably attempt the chamois repair in the near future. This was an easy and quick attempt (my first) at repairing these and I am truthfully nothing but happy with it. my coworkers asked me if the sub was on with some Parliament playing on an mp3 player and were completely surprised to find the sub unplugged and only the sony's bumping with the new surrounds. until I make the chamois surrounds I will let this be and just enjoy.:banana:
 
Aha, I see. That driver is square.

Yeah, the Q would definitely change. But hey, an incorrect surround is way better than no surround at ALL.

I've seen that chamois APM repair- seems to me that's Q-changing, too, and a heckuva lot of work, besides.

Why, why, WHY can't someone make replacement surrounds for all these APM drivers? There's a lot of them, in many sizes.
 
The result with the chamois method, from my experience, is much closer to standard foam, though.
 
yes The roll on the surround is alot larger and definitely is not fully seated on the very outer edge of the honeycomb square diaphragm. I was worried about the surround not allowing a large enough throw of the woofer but this does not seem the case and I can detect no audible distortion or sound from the surround. I think the 4 voice coils and suspensions allow it to throw nice and straight and no scuffing. of course a side by side comparison when I do go ahead and attempt the chamois suspension will be in order. I will definitely do so when the time comes.
 
beezle,
How about a picture? I've got the 33w's with surrounds on their last leg, but as you say they still sound great. I was thinking of routing a pattern into a piece of hardwood as a negative form and using tubing to press the chamois tightly into the mould until cured. Sounds simple enough if I'd get off my ass and do it.
Tom
 
ok my phone has no camera so I will bring my camera in tomorrow to the shop and take some. Cosmetically these are a 2 out of 10. when I got the speakers they had something similar to roofing tar on them in spots...no grills... and not in the greatest shape but intact and working. there were a few gouges in the woofer honeycomb that did not affect the sound in any way. consequently I have not been easy on them for the last 25 years as I was about 13 when I got them and they traveled to toga parties in high school etc and they have been in a piano restoration/refinishing shop for the last 10. I was going to reveneer them and finish them but when the woofer foam was going I bought a pair of Monitor Audio MA800 in rosewood with matching stands and these became a 2nd room stereo setup. I guess I am getting older and feel these very worthy of beginning again.
The surround repair is rather crude but mostly just an experiment on my end. the surrounds were butchered off of the original speakers and I did the best I could to try to trim the surround into as flat and straight an edge as possible. I used the glue I chose for the reasons of flexibility, strength, filling capability and ease of removal when necessary...I was not looking for aesthetics,,,sorry. but I will get them pics tomorrow.
 
Here's a picture of mine. The surrounds look to have been crudely fabricated at some point in their past.
Tom
 
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ok I took some pics. again cosmetically they are nasty but I was really looking for functionality.
 

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sure I had them opened just a few weeks ago and I think the allen key wrench is still sitting on top of one of them. I will take pics monday with the woofers out. these are some beefy cast baskets with the four voice coil design
 
APM-8 pic

sure I had them opened just a few weeks ago and I think the allen key wrench is still sitting on top of one of them. I will take pics monday with the woofers out. these are some beefy cast baskets with the four voice coil design

Here's the link to my APM-8 woofer, before the foam fell off:

http://www.audiokarma.org/forums/attachment.php?attachmentid=140146&d=1236372417

I started the chamois process, but haven't had time to finish it yet. I took a flat board and glued half-round wood to it as a form, the wet the chamois with starch and pressed/clamped it to the board. Turned out pretty good, just have to glue it on the diaphragm now, and loosen all the screws that hold the little clamps that hold it to the frame. Soon it will be :music: thumping once again.
 
nice looking woofer. definitely looks like an earlier version than mine. I will post the pics of the back from different angles on monday.
 
here' s the pics of my woofer. as you can see its got 4 voice coils and the rear suspension piece.
 

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Search some older threads....there's a European Company that ships worldwide, they have several square surround sizes, although not all of them.
 
yes thanks...I have researched rather extensively on the web for an easy "fix" for surrounds. several companies (speakerbits) and another I believe offer square surrounds but you will not find any bigger than 6.5 inch. these are in the realm of a 10-12 inch woofer. I believe I am the only one yet to have found an exact fit for any square surround in this size. I would love to be proven otherwise but I believe to be alone in my findings. by all means if you or anyone can find an alternative to the kicker surrounds please share....otherwise I will just chill and wait until I do the chamois repair. thanks
 
Chamois works as an excellent alternative but is a very labour intensive process (as you stated in an earlier message) Just have a look at the 5" woofer (APM-158) in my avatar. :banana:
 
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