Dynaudio M2 - No sound from tweeter or midrange

[projectaspen]

Just got an used Dynaudio M2 pair of speakers. I knew they were not in mint condition, but after the long shipping distance, one of the speakers doesn't seem to be working properly. The sound is baffled and not like the working speaker. I suspect that the midrange and tweeter are not working.

Since the previous owner said they were working, I was thinking of disassembling the drivers to see if there's something disconnected. Now, I never did that to any speaker, I don't even know what I could find there... Is there any chance that this could work? Is it even safe to do that without destroying something?

My original plan was to buy replacement drivers and have them repaired...

 

[TMM]

If both the mid and the tweeter are not functioning then I think it is more likely that there is a connection problem (bad solder joint perhaps?) on the crossover circuit board, or between the circuit board and the rear terminals. I think it's unlikely that both the mid and tweeter disconnected independently in shipping. Either way, my first course of action would be to open them up and have a look.

The drivers can be removed individually from the baffle by removing the following screws:

Be aware that the drivers probably have some kind of foam gasket sealing them to the baffle so after removing the screws they may still remain stuck in place - you will have to carefully lever them out somehow (i'd recommend via the screw holes so any witness marks are hidden by the screw), or once you have one driver free you can reach into the box and push them out from the rear.

Alternatively it looks like the whole front baffle might come off as one assembly if you remove the bolts around the edge.

Good luck!

 

[projectaspen]

thanks, I might try this...

it definetely looks like I could remove the whole thing if I unscrew all parts...

regarding the tweeter, it looks like its part number is 81622... It's a part used in many other Dynaudio speakers so I thought I could find some guidelines on how to disassemble it and reassemble it but no luck...

I was afraid of this foam thing... I think that if I open the speakers I might not be able to make them the way they were.. Well, apparently they were serviced for woofers already, and maybe the midrange and tweeter stopped working after that, I'll never know for sure...

I'm also fearing that even if I buy replacement midrange and tweeter they still might not work... If not, only the crossover would be the problem, or is there something else in the speaker?

thanks again

 

[giralfino]

IMHO, you are approaching this in the wrong way. If the seller said the speaker were working, and instead one is not, you should return the speakers and have all your money back, both shipping included. At least this is what I would do.

If you are planning to recover the broken speaker, be aware of the potential costs, and if it is possible at all. But before you need to understand the problem, something you don't yet, as you don't even know if the problem arises from the tweeter or midrange or both!

So a sensible approach to understand where the problem is could be:
0) try changing the speakers at the amp side (with your problem this is probably stupid to do, but if one whole speaker is not working, this will assure that the problem is either in the amp or speaker)
1) try to find what driver is not working. You do this in many ways: run pink noise and go near the speaker, one or two drivers not working will be obvious. Alternatively run a frequency sweep, if one or two drivers don't work you will notice a lack of sound at some frequencies.
2) if you find a driver not working, then you need to look inside. Pull out the non working driver, access also the crosover board, and check the connections. Sometimes if there is some oxidation on the fast-on simply open and close the connection some times.
3) if the problem persist, try swapping the non working driver between speakers. If the problem goes with the driver, then it's the driver, else is the crossover.
4A) if it's the driver, look for something obvious like a broken wire, it can be repaired (I did it), but probably you need to replace it.
4B) if it's the crossover then it could be a bad contact or a broken element. First thing I would do is to carefully remelt all the joints, protecting the elements from over heat (with alligator clips for example).

Hope this helps

Ralf

 

[projectaspen]

Yea, returning would be the thing to do perhaps, but I had some hopes I could fix it easily...

I'll run the pink noise through it, but to me it's pretty obvious that both midrange and tweeter aren't working. Midrange because it was pushed in and in really bad shape, and the tweeter because of the lack of high frequency sound.

To get things to a really next level I think some dents on the wood are termite infection... That could explain the corrosion on wires. I just had an old Yamaha speaker that had some termite, unfortunately I didn't look closer on the Dynaudio, but there are some very little holes in the cabinet which look like it...

Now I definetely won't be opening this speaker myself, I could try to return the speakers but by now I doubt the people that sold to me will be reachable. I could try to sue them, because I actually asked if there was termite in the speakers before receiving, since I had a previous problem with it.

If I do get stuck with it, I could treat the speakers for termite but no chance I'm opening it...

 

[giralfino]

Pushed in domes, midrange or tweeter is the same, doesn't mean a non working driver. It can be reshaped. Usually a broken tweeter has a broken or melted wire, or a dried ferrofluid, something that is more difficult to repair, if possible at all (the melted wire for example).

Anyway, if you don't open the speaker you won't understand where the problem is and can't fix it.

Ralf

 

[projectaspen]

Pushed in domes, midrange or tweeter is the same, doesn't mean a non working driver. It can be reshaped. Usually a broken tweeter has a broken or melted wire, or a dried ferrofluid, something that is more difficult to repair, if possible at all (the melted wire for example).

Anyway, if you don't open the speaker you won't understand where the problem is and can't fix it.

Ralf

I'll try to return them, I don't want the risk of opening the speaker and finding out that is infected by termites... I thought the dents were dents, but there are some tiny holes in the cabinet which can only be a case of termite.

 

[ODougbo]

The marks/holes could've been made by a pointed spikes found on some speaker stands.
However Google powderpost beetles, they are a sneaky little insect!!!

If you're really worried about this type of thing you should wrap them up in plastic and seal them up fast!!
Freezing the speaker boxes for two weeks is also a option.

 

[projectaspen]

The marks/holes could've been made by a pointed spikes found on some speaker stands.
However Google powderpost beetles, they are a sneaky little insect!!!

If you're really worried about this type of thing you should wrap them up in plastic and seal them up fast!!
Freezing the speaker boxes for two weeks is also a option.

Now I swear that the holes could also be from this powderpost beetle you talking about. Except that there's also that pattern that termite leave on walls, on the side of the speaker (the bottom facing side).

I just had the exact same problem with a vintage speaker. I found about it when there was some powder from the wood in my stands...

Then I had a termite specialist to check my house and the speakers. He said that my vintage speakers had them, and also my house. So I actually had my house cleaned for termites THIS week. The technician also told me that the termites make small holes, exactly like those found in the M2... Not only that, there's that pattern in the speaker bottom that termites leave after they act...

It will cost me a bit, but I'll definetely will try to return the speakers. I thought that the pattern (or dents) were from touching a wood surface damage but when I woke up I noticed the little holes, a few of them.

So the speakers aren't working because of this probably, as termite consumes everything that has cellulose...

The technician also told me that once the poison is there, the speaker is clean, but if I have to open them to make them work, it's really unacceptable. Also the business attitude of selling goods that can damage other people's property should not be accepted...

Well, anyway, it's my 2nd straigh termite issue, so I think it's a heads up for anyone on the used market for speakers...or anything made of wood for that matter

 

[mtoc]

A few guys already told me dynaudio M4+ is almost better than everything in this world.