ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Here is a closer look at the 10 inch driver before cleaning. You can from the dust and insect remains that this speaker has not been in service for some time. In fact, on the spider underneath the cone I found a real, live spider. Kind of humorous. It is no longer a live spider.
The old glue on the metal frame was harder to scrape off. The glue on the cone was also tricky as it wanted to pull up paper from the cone. I lost a small bit of paper but I didn't want the layer of old glue. There was also glue that went over the edge of the cone to the back. I think I got it cleaned up pretty good in the end. The cone material is stiff all the way around and out to the edges.
This is the first speaker 10 inch woofer ready for the new surround...but I am going to remove and prepare the woofers from the other MS150 speaker first. I sanded out a couple of the rust patches of the speaker frame and hit it with a little semi-gloss black paint.
One last picture tonight. I pulled the two woofer drivers out of the second MS150 cabinet. The 10 inch was just as easy as the first one to separate the driver from the gasket and frame. The 8 inch was harder. The gasket had been glued to the foam surround. The speaker was probably assembled before the surround and properly dried or someone just decided to glue the gasket. There was some oil on the side between the frame ring and the gasket so maybe someone before me had attempted to separate the pieces and gave up. I was able to eventualy pry the pieces apart without destroying anything but the gasket has a few cracks. I think it will be okay. I don't think you can buy replacement gaskets like the one pictured can you? Anyway, these two drivers are out and ready to be prepped.
John I dont like glue on paint, IMO its better to glue directly on the steel surface.
Collecting Vintage B&O is not a hobby, its a lifestyle.
I attached the first 8 inch foam surround to the cone today. The fit was very tight. I marked where then inner foam ring edge covers the cone and it appeared to be the same distance all around.
On this first surround I applied the glue to the underside of the foam surround. It is angled to meet the angle of the cone. In the picture with the glue I had to snap a quick picture just to show what the glue looked like. Before I attached the surround I made sure it was spread evenly. The glue I have used on all my refoam projects is some glue I got from Simply Speakers. I know some people on the forum here haven't liked their surrounds but I have bought glue and grill cloth fabric from them and had good success. Their glue is clear and sets up very quickly. It stays down when you press it in place too.
The second picture shows the surround glued to the cone.
Next I glued the 10 inch surround to the 10 inch woofer cone. The 8 inch driver cone is a plastic type material (very smooth). The 10 inch driver cone is more of a paper type material. The surround for the 10 inch woofer looked like a good fit but the amount of foam surround that contacts the cone is less that what the 8 inch driver had. On the 10 inch surround I applied the glue to the edge of the cone making the width of the glue trail the width of the old glue markings. The surround attached nicely. I went over the glued area several times as it dried to make sure there were no air pockets and everything was nice and smooth.
Now....bad news
As I prepared to attach the surround on the second MS150 8 inch driver I noticed the cone was frozen. It doesn't budge. I opened the dust cap and sure enough one side looks fused together. It must have happened when I was handling the driver during cleaning I think because I'm sure it was okay when I pulled it out of the cabinet. Quite disappointed.
I will have to temporarily borrow one of the 8 inch drivers from my S120.2 speakers later when I am ready to test these MS150's. I will finish the other 10 inch driver surround then prepare the shims.
Continuing on with the other three woofer drivers that are ready to shim, I started with the 10 inch driver that is from the cabinet with the ruined 8 inch driver.
I picked up some sheets of acetate from my local art supply store. They only carried three sizes: 0.003 gauge, 0.004 gauge and 0.005 gauge. So I bought one sheet of each. Starting with the 005 gauge I cut a strip that was 5 cm wide and 11 cm long. I cut away the dust cap of the driver and inserted the acetate strip in the slot the cone travels. It fit easily. Next I cut three shorter 5 cm wide strips from the 003 gauge acetate to position evenly around the gap. That made the fit so it was snug but I can still move the cone. So I think I'll replace the 003 gauge strips with 004 gauge strips. My understanding is that the shims will ensure an equal distance of the cone around the pole (is the right terminology?). With the shims in place I should be able to position the cone so the top is level and the outer edge of the surround is exactly where it needs to be glued to maintain that position.
Here is a picture of the acetate shims on the 10 inch driver.
I tried out the 004 gauge shims instead of the 003 shims but there wasn't enough space. So the shims I am using are the 005 + 003 gauge acetate strips. Since those fit nicely (all the way to the bottom) where the cone is straight and level I went ahead and glued the surround to the frame. Tomorrow I will give the driver a test.
Nice clean job John
Thanks Søren.
Today I removed the shims. What a great feeling to try out the movement and see that the travel feels perfect. I hooked the driver to a signal generator and pumped it with a 0.4v sine wave from 20 Hz to around 160 Hz. It sounded just as I expected it to. I must say using the shims worked as well as advertised and I feel more secure in the repair having seen the cone evenly spaced around the pole.
I still have the other 10 inch driver and the remaining good 8 inch driver to finish the surrounds on. It is really tempting to not do shims on those two because their movement with the surrounds only attached to the cone move without any rubbing. No worry though, I will go ahead and use shims on them. I am curious on the 8 inch driver anyway because I want to see what a good one looks like under the dust cap.
Here is a picture of the completed first 10 inch driver. The cone is a little ragged from age. There are a couple of spots on the dust cap that are brownish. I think they were spider eggs. I tried cleaning them off but I might have to eventually put on a new dust cap. The glue I used around the dust cap where I made the cut is Aleene's clear tacky glue but the old glue underneath it yellowed. It is still drying so I'll see what it looks like tomorrow.
Update on the bad 8 inch driver....
Tonight I took apart the 8 inch driver with the frozen cone. First I cut away the spider from the frame and un-soldered to two leads from the cone to the frame connection points. The cone and voice coil assembly still wouldn't budge. So I pulled the spider and cone from the voice coil. I checked the gap between the center pole (doughnut in this driver's case) and the voice coil with my acetate sheets. They wouldn't go all the way around as I was sure they wouldn't. There was no way to get the voice coil out because the center, doughnut shaped pole was leaning against it. With nothing really to lose I tried my channel lock pliers by bracing one side to the side of the driver frame and the other inside the doughnut. As I slowly squeezed the pliers shut the center pole rocked away from pinching the voice coil. The pole stayed where I had rocked it and the voice coil easily removed.
Here is a picture of everything apart.
Here is a picture of the straightened center pole and the voice coil removed. The upper ring area of the voice coil (above where the wire windings are) is pulled away.
The question now is can this driver be repaired. I would think the voice coil could be repaired and re-attached to the spider and cone. I'm not sure about the center pole that I was able to rock back into place. Why was it loose? Since I can only move it with pliers would it function okay as a woofer if the other pieces were repaired? Or would it eventually rock back against the voice coil and freeze up the cone again? I know of a good speaker repair shop about an hour and a half drive from me. I spoke to them on the phone yesterday and they really haven't done any work on a Peerless driver before (this 8 inch driver was made by Peerless for B&O). However, they are very experienced speaker shop (45 years in business) so it might be worth taking over to them.
Here is a picture of the voice coil assembly separation from the other side (the inside of the tube). It looks repairable to me. The gap/channel where the voice coil moves is a lot wider on this 8 inch driver than on the 10 inch driver I just finished the surround on. I think there would be enough room add material to repair the voice coil assembly and still slide in and out of the channel. The question is still about the integrity of the center pole and if it needs anything done to it.
This morning the glue on the dust cap of the re-foamed 10 inch driver is dry and the yellowish coloration where I glued is gone.
"When I had a pair of these, I had them reconed with a rubber surround. The sound was excellent - Recone Lab were so impressed they put them through their sound chamber - ruler flat response! They are the pair pictured here."
I am now the extremely happy owner of these - they put a smile on my face most days.
I wish you every success with the restoration and your relationship with your neighbours!!
Cheers
Nigel
BTW - Great thread & photos!
About the voice coil, I would try to repair it with thin paper (bible paper) on both sides with epoxy, then find a plastic tube that fits inside, to get it nice and circular again, eventually you will have to sand down the epoxy to get it thin enough.
The center pole, is it possible to epoxy it all around at the arrow, I cant see what material you have at bottom, but if you epoxy it make sure it is centered.
Then get a new spider, cut the outer D to fit, then, with a circle, mark and cut the center hole, shim the voice coil (hard fit) and position it exactly in the heights and glue it to the spider, let dry and then glue the spider to the basket. When dry glue the cone carefully centered to the coil, when dry, glue surround to cone, when dry, reshim to light fit and glue surround to the basket.
I would not leave the center pole as it is now, it may come loose again.
Good suggestions Søren. I examined the driver again and took these photos. The center pole is definately going to determine if this can be fixed. I used a tripod to fix the camera directly over two opposite sides of the voice coil channel and I can now see that the center pole is not exactly centered. It is centered enough to allow the voice coil to be removed but as the pictures show, the gap is not the same all the way around. Ideally the center pole part would be pulled and re-aligned into correct center position again (epoxied in place). I don't know if that is possible. I will have to make some time to take it to the repair shop and see what they say.
Here is a picture of the 8 inch driver viewed from the bottom. You can see the ring where the center pole in mounted.
@Sonavor: I am sorry to hear about your broken driver, but I hope it will be functional again. Otherwise you will have to look after a donerspeaker. I have a driver from a MC120.2, which is identical to yours, but the Post Service here in Denmark destroyed it a few years ago, and the basket doesn't seem repairable (It went to pieces).
It’s about 1,5 year ago I chose to upgrade (Or what you would say) from a pair of Beovox MS150 to a pair of Beolab Penta MKIII. Since then I have regretted selling my Beovox MS150’s, which had to go at the time because of space problems. A few days ago I found a pair of Beovox MS150.2 that just were too good to pass. They are almost as new except for a few scratches on top. I don’t think I will be using them daily, but I’ve missed the sound and look of them, and it is nice to could be listening to them once in a while when they have been renovated at some time. I can also see that they have got desirable collector’s items through the past few years, and I’m very glad to own a pair of these beauties again. I will never part with these ones! The Beovox MS150's and Beovox MS150.2 are fantastic speakers, and I hope you also are going to be able to enjoy yours.
- Dennis
With the stands too, nice. It looks like you will be getting the woofer surrounds replaced soon. I am getting anxious to hear what the MS150's sound like. Right now my target date is sometime next week (maybe next weekend but hopefully sooner).
Tonight I shimmed and glued down the surround on the good 8 inch driver. The width of the channel where the voice coil travels measured about 1.5 mm. The diameter of the center pole is 7.5 cm. I cut two 23 cm long x 6 cm wide strips of my remaining 005 gauge acetate. I fit both strips into the channel. Then I put smaller 005 gauge acetate strips between the two long strips to make the fit tighter. I could still move the cone but it was pretty snug. I felt that was a good shim. As I already knew, the width of the channel I had to shim on this driver was quite a bit wider than the 10 inch driver.
The attached picture shows cutting the dust cap and the shims all in place.
Here is the 8 inch driver with the surround glued to the frame. Tomorrow I will remove the shims and give it a test with my signal generator.
Managed to get the second 10 inch driver shimmed and the surround glued to the frame. So both the 8 and 10 inch drivers will be ready to test tomorrow. I shimmed this second 10 inch driver a little tighter than the first. I was able to re-use the long 005 gauge shim from the first one but I used 004 gauge shims for the second layer (instead of 003 gauge).
The 8 inch and 10 inch driver refoams are finished and came out as good as the first 10 inch driver. I glued the dust caps back on already. I was trying to decide if I wanted to quickly put the drivers back into the cabinets now and see what they sounded like (which meant I would also have to open one of my S120.2 cabinets to borrow the 8 inch driver)....but decided against it. The speaker trim pieces still needed cleaning, the crossovers still have to be recapped and I want to clean up the cabinets.
I put the plastic trim pieces in a tub of warm, soapy water and cleaned them up. Next I took one of the cabinets and took out the 8 inch tube with the damping material. While working on the refoam of the 8 inch drivers I realized that I had a black plastic ring (a sleeve) with the driver that really should have stayed with the dampening tube. The tube also had places on each end where the paper was starting to unravel. I place the plastic driver sleeve into the tube, applied some Aleene's Tacky glue at the edge of the tube and the inside of the tube. For the paper that was unravelling I used the same glue I used for the surrounds. Here is a picture of the tube with the driver sleeve back in place.
OMG you really run into everything possible with these speakers, its interesting to see what you are doing, waiting to see what happens with the bad driver, I hope it can be saved.
I have the crossover for the cabinet removed and ready to recap. There are a couple of inductors that are not as secure as the should be so I will reapply some tacky glue where the original glue came off. As I showed in earlier pictures of this project, it looks like someone has worked on the speakers before. There were some spots I could tell were new glue instead of the original. The back of one of the inductors has a chip in it. That inductor is firmly in place though and appears to have original glue. I wonder how the chip would occur. The trace side of the board is opposite the back of the tweeter and midrange housing so it is not exposed where it could get hit (if someone was poking around inside). It would have had to be chipped when someone was working on the board I think. Here is a picture.
The cabinets seem solid and everything seems intact. This pair of MS150's just suffered through a long period of storage where they weren't in use. But I also think they weren't in use because maybe there was a rattle in the cabinet. Maybe loose inductors on the crossover PCB (judging by the fact several have been re-glued). I don't think the 8 inch driver can be saved. The center pole is solid enough where I can't move it by hand but it is loose. It really needs someone with the right speaker tools to take it apart and reset it.
sonavor:That inductor is firmly in place though and appears to have original glue
The inductors on my 3707 was glued with a glue a lot darker than yours, 2 coils was loose from transport, I didn't use tacky glue, but silicone and let dry over night.
The wood cabinet is the another task I will have to do. Here is a picture of the bottom of one of the cabinets. Both look the same. You can see the remains of the duct tape that held on a plastic screen. I am guessing the screen was to keep rats/mice out of the bass port while the speaker cabinet was in storage (surely it wasn't used like that). My plan is to remove the remaining duct tape residue, tape off the black plastic bass port trim, then lightly sand the bottom of the speaker. After that I will apply Søren Mexico's refinish treatment and see how it looks. If I get it to look like his finishes I can proceed with the rest of the cabinet.
Sanding will be very difficult with the bass port in, try Iso alc. on the tape remains, if it don't come of try with acetone, but careful with acetone on the plastic ring.
I plan on taping off the plastic ring...maybe even removing it it if is easy.
On your earlier words Søren: "... you really run into everything possible with these speakers"That set off an alarm in my head. I have only concerned myself with the woofers and the crossovers. What about the midrange and tweeters? So I just tested the midrange and tweeter drivers. One midrange is dead. So out of 2 tweeters, 2 midranges, 2 eight inch woofers and 2 ten inch subwoofers - I have one bad midrange and one bad eight inch woofer to replace.
Correction on picture of 8 inch driver dampening tube. I was checking my work and realized the plastic driver sleeve for the 8 inch woofer has an indention (lip) half way up the sleeve. So the I don't think the sleeve goes all the way into the paper tube as I show in the earlier picture. The tacky glue is slow drying so it was easy to reposition the sleeve where it needs to be. Here is an updated picture.
Dillen had me check the resistance of the midrange (a 3 inch phaselink driver) to see if it was open. It was so I took it apart and one of the coil leads had broken off. Here is a picture of the coil - one lead is still attached and the other is broken. I will need to scrape a little insulation off and see if I am steady enough to reconnect it (tomorrow).
I just love the pictures. Good luck with the job!
--mika
I agree - Great dedication :) BTW while you have those mids apart check the glue between coil former and dome - They tend to separate with age and that would be a shame to happen after putting the thing back together!
Olly
sonavor: Dillen had me check the resistance of the midrange (a 3 inch phaselink driver) to see if it was open. It was so I took it apart and one of the coil leads had broken off. Here is a picture of the coil - one lead is still attached and the other is broken. I will need to scrape a little insulation off and see if I am steady enough to reconnect it (tomorrow).
I've read on other sites where repairers of tweeters with broken voice coils just discard the broken bit and unwind the coil one turn. How many turns do these coils have? Are there multiple layers?