Imbalanced Speakers

[Loz]

Hi all,

So this is a bit weird. On first impressions there seems to be nothing wrong with my ESLs. However, the more I listen to them, I get the sensation that one speaker is somehow louder than the other. It's subtle, but over time becomes very annoying. The image seems to be shifted slightly to one side. I've swapped speakers over and indeed the effect switches sides, so it's not the room, which I assumed for a while. I've eliminated cables, amp channels, source channels and power supplies from the equation, so I must assume it's the speakers and not anything else. All this being said, it's still hard to put my finger on the problem exactly as it is not obvious.

I've done my best to take frequency sweep measurements of the two speakers individually, co-located at the centre of the room at a mic distance of about 1m. I don't think I've done the measurements particularly well, but I've tried to be scientific. Up to 140Hz the measurements between the two speakers match well, 140Hz-1kHz they both vary a lot with frequency but neither is obviously dominant, above 1kHz one is always louder. This difference increases with frequency, with the difference at 13kHz being about 4dB. I'm not sure how well the two speakers should be matched in the first place, so not sure if this is within tolerance or not.

If anyone has any experience with this sort of thing it'd be much appreciated.

Thanks in advance,

Loz

 

[roberto]

Hola Loz,

If you have an imbalance sound, and I am assuming that the left side is louder than the right side, you swap the speakers, is the same side with the the imbalance? In other words, the problem remains in the same side?

The ML are very capable to show imbalance channels. The culprit could be one interconnect cable or your preamplifier or your power amp. Please give us your components system and your ML speakers model too.

We will try to track from where the problem is...


Happy listening.

 

[Loz]

Hola, no if you swap the speakers from left to right the imbalance moves with the speaker, from left to right.

 

[roberto]

Loz, you have a bad stat panel. If you want to be sure about this, swap the panels. Tell us your speaker model please.

You can do the washing procedure. Sometimes this helps to revive the panel again.

http://www.martinloganowners.com/~t...n Logan Quest Stator Panel Shower Washing.pdf

 

[TomDac]

vacuum the panels after leaving them unplugged overnight. this may help.

 

[Loz]

The model is the EM ESL

 

[roberto]

Loz,

Electromotions stands with a 5 year warranty. Just contact the Martin Logan service department. Give to them a call or just write to them an email. They will help you to solve your problem.

By the way, I love the Electromotions quality sound. They have being nominated as Product of the Year some time ago.

Happy listening!

 

[sleepysurf]

Just out of curiosity, how did you actually MEASURE each panel? Did you use good software with a properly oriented calibrated mic, and positioned (relatively) near-field? Unless your room geometry and speaker placement are symmetrically identical, it would be best to measure each speaker in the exact same position (eliminating any issue from room acoustics).

BTW, I had a similar issue, years ago, with poor bass response of my Summits. The problem was clearly illustrated in my XTZ Room Measurements (see thread... http://www.martinloganowners.com/forum/showthread.php?9648-Bad-Summit) and Jim Powers (former superb ML Tech Support guru) identified the problem as a misconnected woofer! I had purchased the Summits used, and the original owner had apparently "operated" on them prior to my purchasing them.

 

[Loz]

Roberto - I bought them used so I'm not sure if they are under warrener or not?

 

[Loz]

Sleepysurf - I've done near field measurements, but maybe not good enough. I'm using REW with a mini DSP calibrated mic. I want to do a few more tests. I'll do these and then post the results asap. Thanks for the help.

 

[roberto]

Roberto - I bought them used so I'm not sure if they are under warrener or not?

Just send the serial NO. of the bad speaker, and say that you can't find the invoice. On the other hand, the service department of Martin Logan is for help! You do not worry, just ask them for help, and how to track your problem. They will guide you step by step.

Happy listening!

 

[Loz]

Just checked, I'm out of warranty ��

 

[roberto]

Loz,

At the Electromotion model, you are allow to buy only one stat panel. Usually in the other models, the panels are matched. Yours are not. This does not mean anything. Your Electromotion are great sounding speakers. Just ask for a quotation your needs. They are easy to replace...just follow the directions that comes with the new stat panel. I do not know a way to make a panel back to they previous efficiency, sometimes the shower procedure works!

Happy listening!

 

[ttocs]

Take Tom's advice try cleaning the panel first - but only after it's been unplugged for at least 6-8 hours. You must do both sides, front and back.

Vacuuming with a hose attachment is a quick and free attempt to see if it's just dusty. About 5 years ago I had gotten out of the habit of vacuuming the panels and they lost volume at higher frequencies. I hadn't vacuumed them in over 8 months. After a 20 minute vacuum they sounded normal again.

I usually vacuum every couple months. The panels are electro-static, hence they attract dust.

 

[zigman]

If vacuuming doesn’t help, then it is most likely the panel. Same thing happened to my Source speakers. Thought something was off, did some tests like you did, and ended up sending the panels in to ML. Long story short they tested and there was a 3db difference between panels. Also, try removing the panel and see if there are any loose connectors.

In my case I got a really good deal as open box at Magnolia, so I probably bought them this way. Too bad I hadn’t checked when I bought them, since ML would have covered under warranty back then. Just give ML support a call, they are amazing and are very helpful. In my case, I chose not to replace the panels and moved those speakers to the bedroom and adjustedthe balance on the receiver.

 

[Loz]

Hi all, thanks for your help.

Tried vacuuming and didn't do anything. I checked with ML and the speakers are 5+ years old.

Annoyingly, I live in the UK, so I have to go to a distributor rather than to ML themselves. Before I go through all this with replacing a panel I want to 100% sure it is the panel, as I can't afford to just assume that getting a new panel will fix everything.

I've attached a bunch of images of the measurements I took (hope the attachments work, as I couldn't get the insert image option to work).

Basically, I used the same channel and cables and power supply with each speaker. The speakers were placed in the same spot, in turn, in the center of the room for each measurement. Measurements were taken at heights of 15cm, 60cm and 110cm, in the near field on axis.



I'd like to know your opinions on the measurements, as to me yes it does look like it could be the panel, but something else, sub 400Hz seems to be going on in some of the measurements. Could this be something to do with the crossover?

In any case, I think I want to do a panel switch just to be sure before I send anything to the distributor. Is there a guide for panel removal for this model on the forum? Or do I need to ask ML about it?

Thanks again for all the help.

Loz

 

[Loz]

OK, the images came out in the wrong order.

From top to bottom:
1. height: 60cm (bottom of panel), 40cm distance from panel
2. height: 15cm, 30cm distance from driver (zoomed view)
3. height: 110cm (3/4 up panel), 40cm distance from panel
4. height: 15cm, 30cm distance from driver (same as 2., but full range)

 

[roberto]

Loz,

swap the panels. It is an easy thing to do if you have the tools. No big deal. If you swap, and you find that the panel is the culprit...to do washing procedure...not a difficult thing to do and also will save some good money. I do represente here in Costa Rica Martin Logan, and also I am the one who service their whole line.

PM if you need further instructions.

Happy listening!