distirtion/vibration on summit panel

[Antipodes]

I have an occasional distortion in one panel of my Summits (not X). Actually I think it might be there all the time but it is worse with different frequencies, sometimes almost absent with some tracks and standing out like canine appendages on others. It began as a slight warble in the mids but is now a little higher pitched and very noticeable at times. It sounds as if the panel is vibrating on something. Even when not being obvious there is a slight hardness to the lower treble that shifts images towards that speaker. Looking closely at the panel, I can't see anything wrong, but the horizontal dampers look a little puckered when looking from the rear.

I have vacuumed them, given them a blow-wave, with no luck. I have sent an email to Martin Logan asking for advice but with no reply yet. I have tried googling etc and even searching here but perhaps I am not using the best search terms.

Can anyone tell me whether I should just get new panels or if there are options I can try first. Or something I can do to narrow it down.

Not being terribly used to panels I am not sure what to try next.

 

[JonFo]

The best way to sort out a resonance problem, whether in a speaker or in the room is to play steady tones at the various frequencies you suspect there is a problem, or doing a sweep across the band to tease out the resonance.

You will need a test CD or some source of varying frequency test tones. A great source of this is AudioTools for iPhone. A signal generator is part of the included modules, as is of course SPL meter and RTA analyzer.

 

[JonFo]

Remember that resonances are often volume dependent, so just because it did not 'buzz' at a low volume, does not mean it's not there. Do sweeps at increasing volume levels until you hear it.

I found an acoustic treatment panel was buzzing in my room at a very low frequency (30hz) at very loud volumes (>90dB). It took a sweep at a decent level to uncover that one.

 

[jmschnur]

In my case for my Montis, I found a coupling to my supported floor. I put accoustic dampers underneath my speakers and there was no more issue.

My floor is getting old and is in the 2nd story of a 35 year old house.

When I ran 50-70 hz the speaker really shook.

I used small acoustic dampers for washing machines. I believe hockey pucks will also serve.

Of course you will need to sort out if the issue is in the frequency domain of the panel, or below the xover.
J

 

[Victor]

Hello Antipodes,
Apologies for the belated response...
It's quite easy for the bass in such a speaker to loosen bolts.

There was no mention but I take it you did the obvious :

1. Levelled & tightened the feet (both equally important)
(If using the spikes on concrete/solid composition floor - with spike shoes of course - I find it helpful to tap each of the rear spikes with your index fingernail. If the spike is properly load bearing it will sound like it. You'll hear the difference if it has a micron gap underneath it - a light hollow sound will be produced. Simply torque the jamnuts until they sound identical.

2. Carefully tighten the panel fixing bolts (perhaps a fraction more than finger tight if using Vantages, probably allowed more with Summits as they use alloy material.)
After that, provided you haven't got the bass controls set to +Xdb, they shouldn't loosen too quickly.

Hope this is helps.

 

[MOON]

One sure way to find out if the panel is defective is to swap out the panels.Put the problem panel in the Summit that has no issues.If you then have a probem with the speaker that used to be operating perfectly, you know it's the panel.

This was the suggestion, Jim Powers (former customer service at ML) gave to me when I had a problem in one of my panels. Sure enough , it was a bad panel after doing the swapping out.

 

[roberto]

Good advise Moon. That is the first thing to do, and make sure it is the panel. Contact Martin Logan service dept. They will guide you step by step to find the problem and fix it!. You can contact Dana ([email protected]). He is a very nice and knowledge Martin Logan service person. Happy listening!

 

[Sambob2]

Hello,

Let me ask you, is it a distorted sound or a buzzing sound you are hearing? The two will diagnose a very different result. Here's my experience...

I had the opportunity to purchase a used pair of ReQuests from the audio dealer which was a trade in. When I got them home I began listening to them first at a low level and then later at higher levels. It was at the higher levels that I started to notice a distinct buzzing sound. I could not figure it out at first thinking that maybe my amplifier did not have the power to deliver into a low impedance. A few days went by and I continued to listen, it was only until one day when the sun was shining into the room and across the panel of the speaker that I realized the curved panel was bent as though the speaker was hit by an elbow or fell onto something. The deformation in the panel was slight but noticeable when the light hit it right. Needless to say I did not buy the trade ins, but ordered a new pair.

Take a very close look at your panel and see if this is your case also. You did say it was only one panel. It is very easy to rule out the electronics by switching the cables from left to right. If the sound stays in the same channel, then it is surely the speaker.