Pernickety panel problem - ideas?

[Stereonerd]

A few months back when I was playing a CD with lovely deep bass fairly loud (but not TOO loud) on my Summits, the left panel stopped working. I got advice from ML and with the help of the good wife (who has better eyes than me) we figured out how to remove the panel and swap it over to the other speaker to diagnose the problem. It still didn't work, so ML suggested I needed a new power supply, which I bought through the local (NZ) ML agent. Two months later the part turned up but meanwhile, life had moved on! When a local distributor heard about my lack of speakers he let me borrow a couple of rather nice Gauder Akustik floorstanders. But when I plugged my power amp in there was no left channel. Hmm! So, I then plugged his power amp into my Summits and BINGO! My speakers were working fine! I assumed that somehow my diagnosis had been faulty and that it was my amp that was the problem all along, not my Summits. Good old ML! About a month on and I bought the rather excellent AVM amp and the Summits were sounding AMAZING. Until last night when I cranked them up on an electronic record with low bass and... the speaker's panels stopped working again. So it WAS the Summit after all. But somehow, it started working again. I turned everything off last night (at the wall) and this afternoon switched the cables around on the amp just to see. Bingo! Both speakers worked. For about 10 minutes. Then the panel stopped working again. So... (deep breath)... anyone here technical adept or experienced enough to have an idea of what's wrong? I've got an unused new power supply that I could try if needed, but given the scenario, is it likely that what's wrong IS the power module? Or perhaps faulty wiring to the panels? Thanks in advance to anyone who is kind or foolhardy enough to reply to this!

 

[JonFo]

About a month on and I bought the rather excellent AVM amp

Which exact make and model? A Link to the product page would be great.

this afternoon switched the cables around on the amp just to see. Bingo! Both speakers worked. For about 10 minutes. Then the panel stopped working again.

It sounds like the amp you are using to drive the summits is going into some protection mode when playing this type of content at those levels. It's not uncommon on amps not designed for the highly reactive loads of an ESL.

But just in case, I'd double-check the cabling between the amp and the left Summit, if there is a loose fitment somewhere or some other thing that might get jiggled loose when that speaker is playing loud bass notes. A banana plug jiggling in the input socket of the speaker could also drive the amp into protection modes.

On the other hand, the 'loose wiring' theory would also apply to the internal wiring on the particular speaker. So opening it and carefully checking all connections might be advised. But leave it unplugged for several hours before poking around inside.

 

[ttocs]

Exactly as JonFo says, check the wiring! Things get loose over time.

Also, is it only the Left channel that has the problem, and never the right? If so, then swap the speaker cable connections AT THE AMP only and try again. If the Left Channel of the amp cuts out, which is now playing on the Right Speaker, then you now it's something in the amp. But if the Left Summit cuts out, then you know it's the Summit Speaker.

 

[Stereonerd]

Which exact make and model? A Link to the product page would be great.


It sounds like the amp you are using to drive the summits is going into some protection mode when playing this type of content at those levels. It's not uncommon on amps not designed for the highly reactive loads of an ESL.

But just in case, I'd double-check the cabling between the amp and the left Summit, if there is a loose fitment somewhere or some other thing that might get jiggled loose when that speaker is playing loud bass notes. A banana plug jiggling in the input socket of the speaker could also drive the amp into protection modes.

On the other hand, the 'loose wiring' theory would also apply to the internal wiring on the particular speaker. So opening it and carefully checking all connections might be advised. But leave it unplugged for several hours before poking around inside.

The amp is an AVM Evolution SA3.2. There's not much about this model online (in English, anyway) but it's a cracking good power amp.
I must not have explained quite clearly before. I've already switched the cables around AT THE AMP and it's the same (left) speaker that doesn't work... the panels, that is. So I'm picking that what you write about loose internal wiring might be right.

 

[Stereonerd]

Exactly as JonFo says, check the wiring! Things get loose over time.

Also, is it only the Left channel that has the problem, and never the right? If so, then swap the speaker cable connections AT THE AMP only and try again. If the Left Channel of the amp cuts out, which is now playing on the Right Speaker, then you now it's something in the amp. But if the Left Summit cuts out, then you know it's the Summit Speaker.

I must not have explained quite clearly before. I've already switched the cables around AT THE AMP and it's the same (left) speaker that doesn't work... the panels, that is. So I'm picking that what you write about loose internal wiring might be right. Thank you both for your good advice.

 

[Robert D]

Yeah, sounds like loose wiring or maybe that power supply you bought might just be needed. The woofer is still working even though the panel is not, right?

 

[Stereonerd]

Yeah, sounds like loose wiring or maybe that power supply you bought might just be needed. The woofer is still working even though the panel is not, right?

Yep!

 

[Tosh]

It sounds like the same symptoms I had when the small transformer inside my SL3 went flaky:

https://www.diyaudio.com/community/threads/ml-sl3-intermittent-bias-supply-problem.210168/

 

[Stereonerd]

It sounds like the same symptoms I had when the small transformer inside my SL3 went flaky:

https://www.diyaudio.com/community/threads/ml-sl3-intermittent-bias-supply-problem.210168/

In my case, the panel has stopped working entirely. The powered bass is still working.

 

[Stereonerd]

I ended up taking my ML Summit to a service technician, who found a loose wire that he reckons was most likely not connected properly in the factory. So I don't need a new power supply after all - at least the one I imported will be good for a rainy day, as they say! I'm so lucky to have found a technician in NZ who is a genuine hi-fi fan with 30 years of experience (and who owns some ML gear, too).
"Intermittand sound
Hooked up panel and all worked ok, then after a short while it
stopped.
Dismantled amp modules removed front subwoofer to gain
access to panel electronics.
Unit worked while running it in parts, traced to very
intermittand connection on crossover, refitted wire properly,
soak test ok"

 

[JonFo]

ended up taking my ML Summit to a service technician, who found a loose wire

Good to hear it was a simple fix.

One of the downsides of stuffing amps, crossovers etc. into the same box as the woofers is they get vibrated, and any slightly loose connector will eventually come off or cause intermittent issues.

 

[Stereonerd]

Good to hear it was a simple fix.

One of the downsides of stuffing amps, crossovers etc. into the same box as the woofers is they get vibrated, and any slightly loose connector will eventually come off or cause intermittent issues.

Good point! I do like cranking up the volume sometimes and those Summit woofers can certainly "move air". I'm a bit scared to play the particular track I was listening to when the speaker stopped working. Which is a bit annoying. There's nothing worse than having to turn the volume down when you really want to nudge it just that little bit higher!