Recently I needed to replace the speakers on an MX5500. As I could not get any original ones, I modified some from Maplin's. Last night I did another, this time I took some photos of my handywork. Any comments are greatly appreciated.

Well this first picture shows the original speaker with the dreaded foam rot. Also the coils had gone on both speakers.

Craig

After spending most of a Weekend searching for suitable replacements I ended up with these from Maplin's.

30 Watt Shielded Speaker

This shows the size difference to the original.

Original and new speakers.

Craig

First step to modifying the speaker is to remove all of the steel frame, right up to the edge of the foam. This was done VERY carefully using a Dremel Multi tool.

1st speaker after been cut down.

Finished pair

Craig

Next I removed the old speakers from the TV. Then removed the two white horn things(not sure what they are called). Looking at the horns, there are two marks at the 3 and 9 o'clock positions at 12 and 6 there are seams from where they are constucted. At these 4 positions I cut a slit into the horn about 1" long. This allows the new spekers to fit into the horns. On the first MX I did, I did not bother fitting the horns back. This time I worked out how to get them back into place.

This shows the mark at the 3 o'clock position (Right hand side horn)

At this point I soldered the wires from the original speakers on to the new ones.

Speaker fitted into the horn

Note how the wire is fed through the slit I have made in the horn.

Craig

Craig:

Next I removed the old speakers from the TV. Then removed the two white horn things(not sure what they are called).

Those would be the log-line tubes

Thanks for sharing this - I have foam rot in one of my MX6000 drivers and I suppose I'll have to do something about it soon, although there are no audible problems so far. I presume these are exactly the same as in MX5500, and not available new either?

Thanks Mika, I knew someone would know the answer.

Craig

Next it was time to take a saw to the MX. As the new speakers even after been cut down are bigger than the originals, I had to make the holes where they fit a bit bigger. As you can see I cut some from the bottom and some from the outside edge.

Speaker hole after been cut out

For this job I used a one handed hacksaw. Tried using the dremel again but the plastic melts and jams the cutting wheel.

Craig

So now I can fit the Log Line tube (Thanks Mika) and speaker back into place.

Putting the speaker back into place.

Note, that at this point, the speaker and tube will not fit fully back into place. They need to be GENTLY tapped into place. For this I used an 8mm drift. Slowly I worked my way around the speaker until it went into place where I wanted it. If anyone can think of a better way of doing this step I would be glad to hear it. One slip at this point and I could have put a hole stright through the foam suround.Glad to say that did not happen.

Craig

Once the speaker was in place it was a tight fit, and would probably stay there without anything else to secure it. As I wanted to make 100% sure it did not move, I very carefully drilled two small holes in the edge of the speaker. Going straight through and into the black plastic behind. Then I secured it with a couple of self tapping screws.

Speaker screwed in place 1

Speaker screwed in place 2

Craig

Time for a quick test while I had a well deserved fig and a coffee. Everything sounding great, so I refitted the fret. Once this was in place you could not tell the difference.

Left side speaker

Right side speaker

Job done, and another piece of B&O rescued. Total cost £9.98, and a few hours of my time.

As I said at the start of this thread, any commnents are welcome and appreciated.

Craig

Really interesting Craig - great to see another piece of B&O saved from the skip. Hopefully others can learn from this and more MXs can be saved.

BTW - on a similar tip - Tim J is fixing up the BM6000 Quad I bought from you, and it should be back with me in a few weeks. That's one rare piece saved from the bin if ever there was one :)

Well done Craig, and thanks for taking the time and effort to share this with us.
I'll be glad when we can post photo's straight into a thread. Fingers crossed, Keith will have it sorted shortly.

Craig, out of curiosity, what are the outside dimensions & spec's of the original drivers?

Chris.

Medogsfat:

Craig, out of curiosity, what are the outside dimensions & spec's of the original drivers?

I was just about to ask the same so I could order new foams withouth having the tv disassembled for weeks (or do it twice). I like your approach, Craig, but I was kind of put off by the hacksaw part

The MX5500 and MX6000 (mine) have the same drivers, I suppose?

A great thread. Thanks Graig!

Reminds me to check my MX5500 speakers also. Somehow diregarded them as foam rot suspects. Then maybe ordering the foams together with the ones to my Beovox C75:s.

Pekka

Medogsfat:

Craig, out of curiosity, what are the outside dimensions & spec's of the original drivers?

 

Chris.

Chris, the original Drivers were 10 Watt and measure 8CM across. If you want an old one as a pattern, I will pop one in the post for you.

Craig

Tut tut Craig - I think you know what I'm going to say now don't you?

You should have asked me first (you normally do) - I have 4 of THESE doing nothing and they measure exactly 8cms in diameter.

Chris.

Chris, the speaker in your link would fit I think. Although, you might have a strange coloured picture. They need to be shielded.

Craig

Good point

hi craig and chris!

good work craig!

company tangband is doing some very good widerange speakerchassis with 8cm diameter, they´ve got some shielded ones as well.

they sound very good and their frequency range goes up to 20khz, which the maplin one won´t manage.

they offer models with different thiele small parameters, it would be interesting which would be the best parameters for a good bassreproduction in the log line construction, which seems to be a kind of strongly damped open baffle in pipe form .

greetings from munich

jens