Any ideas ?

[rneiva]

Hi, I own a pair of Sequel II. Not even 3 years ago they went to ML's distributor and they received new panels as well as a complete review of the electronics.

Now, 3 weeks ago, one of the speakers started to have a very fade volume. I swapped electronics and it would seem and electronics problem because the speaker with the "good" electronics played well. I sent the bad electronics to the distributor. More or less the same day they told me that there was noting wrong with it, the other speaker has exactly the same problems. I hear the panel and the woofer but the sound is dull. Like it doesn't have power. But it does. The fuse it's OK, I don't smoke, no direct sunlight, etc. And after reading some of the threads, I just vacuumed the panel. It seems strange happening the same thing more or less at the same time.

The distributor wanted me to ship the whole box but I convinced him that with the panels, the electronics and the woofers he has enough.

Does anyone have an idea of what might be happening ? I cannot find anywhere the Service Manual.

Thanks anyhow

 

[Dreamer]

Maybe your amp or preamp is giving out, and it's not the speakers at all...

--Richard

 

[rneiva]

No, I connected it to my Sonus Faber Concerto and they sound great.

 

[roberto]

No, I connected it to my Sonus Faber Concerto and they sound great.

Switch the power supplies...and if the same speaker is weak, then the panel is the one...happy listening,
Roberto.

 

[rneiva]

I've switched everything. Next monday they are going to be shipped to the distributor. I don't know what else to look for.

 

[JonFo]

This is very strange, so both your speakers have started to loose volume then, right?

If so, and you’ve eliminated the upstream components testing with your Sonus Faber’s, it must be in the ML’s.

One possibility is the ‘music sense’ is not sensing correctly and dropping power to the ESL. That would explain a gradual decrease in high-frequency volume.

The other is your power connections are not secure and the speaker is loosing AC. Have you checked that.

The only other thing I could think of is failing caps in the HighFreq crossover, but that would be rare.

ESL power seems to be the root issue here if I understand the symptoms correctly.

 

[rneiva]

I've discharged the panels and put some music without power. Afterwards I connected AC and the difference is very, very small.

Anyhow, the best way is to ship everything for assistance.

If it were only one but both panels ?

Thank you anyhow.

 

[JonFo]

Roger,

This is sounding more and more like the ‘music sense’ is not triggering the ESL diaphragm power to energize. The printed circuit board in MartinLogans is that control and step-up element for the diaphragm, so if it’s not getting AC or not being ‘told’ to turn-on, then it wont provide the necessary polarization and the ESL wont work.

The jumper clips on the speaker wire terminals on the back of the speaker, double check that those are in place and passing current, if you wire the speaker to the bottom set, and depend on the jumpers to drive the high-frequency part, and a jumper is not making full contact (or temporary contact), then you could also experience this issue.

You should also consider if it’s a problem with the output of the ESL energizing circuit, make sure that the red wire from that board is indeed making it to the ESL and than none of the segments of wire to the diaphragm are broken.

Below is a picture of an SL3 board (Sorry, I’ve not yet taken apart my Sequels) that shows the music sense, the AC feed and the high-voltage ESL diaphragm output. Check that all of those are well connected.

 

[rneiva]

Solution

Hi, thank you for your support. I sent everything to the distributor and it came back repaired. It seems the problem was in the electronics: the first one had a resistor out of specifications and the second one had a problem in the step-up circuit and it wasn't feeding the necessary high voltage.

Now they sing as before. Just a slight cold, not a pneunomia that would have costed me 1.000 euros.

 

[JonFo]

Hi, thank you for your support. I sent everything to the distributor and it came back repaired. It seems the problem was in the electronics: the first one had a resistor out of specifications and the second one had a problem in the step-up circuit and it wasn't feeding the necessary high voltage.

Now they sing as before. Just a slight cold, not a pneunomia that would have costed me 1.000 euros.

Roger, great to hear that they are back in service and giving you pleasure.

For everyone else, this is probably going to be a more and more 'common' occurrence in the older gen ML's as they age.
The HV circuits are critical to the functioning of the unit. So if they are not stepping up (or enough), then we will see failures due to that.