Aerius Balance

[ChrisP]

Well I've been told that as a newcomer to this forum I mustn't stalk and that I have to post, so who I am to refuse . I'm looking for a bit of advice please.

I've just bought a pair of Aerius's.

The background is that some time ago, after many years listening to different systems, I reached the conclusion that the only speakers for me were electrostatics. But the shape and size of my room meant that I could never accommodate full-range stats and so MLs seemed to be ideal for me. I think the right model for me (until I can afford a pair of Summits) will be a pair of Ascent i's. I'm looking for as large a panel and as low a crossover frequency as I can accommodate. Anyway, last weekend I managed to get hold of a pair of Aerius at a good price, and got them as a relatively inexpensive trial to see how well dipoles would work within my room.

The first result is that they work very well and it's a route I'm going to continue to pursue

However, there's an imbalance in the volume between the two Aerius speakers.
Serial nos. are AEHH462i and AEHH463i

There's an overall 2-3dB imbalance between them (from the level of adjustment required on my preamp). I've swapped the speakers from side to side and the imbalance moves with the speakers

Does this mean the panels need to be replaced?
Or is there anything else I should be looking at?
For example the music sense circuit?
It seems to me that the imbalance seems slightly bigger as the speakers first self-power up for a couple of minutes, hence my question about the music sense circuit

For reference, they're being driven by a pair of Hypex nc400 monoblocks

Thanks for any advice/information

Chris

 

[Tosh]

In general with close to 20 year old speakers, you should go through and reconnect and tighten all the electrical connectors and check all the screws into the MDF cabinet to make sure everything is tight. Power down for a couple of hours first, so any residual HV bias on the diaphragm doesn't shock you.

As to the cause of your imbalance, once you are certain that the ESL panels are completely dust and debris-free front and back (as debris can cause a leakage path between the diaphragm and stator), and that the three wires to the ESL panel are soldered and connected properly, there are a couple of things you can check without completely disassembling them:
There is a copper strip (not visible from outside) carrying the HV bias charge that runs up along the side of the diaphragm which can become corroded or lose contact as the adhesives holding the ESL sandwich together loosen. If you squeeze (front-to-back) the ESL panel while playing a steady sound, does the level change? If you listen carefully all over the panel with a steady sound playing, are there areas which are obviously lower in level? As you listen closely all over the panel with them powered on but no sound playing, are there local high frequency 'squeaks' (which indicate a leakage point)? Start there.

If those tests didn't indicate anything, you will need to check the soldered connections to the ESL panels, and then swap the ESL panels themselves to see if the problem follows the panel or the power supply. I hope it's not a problem with an ESL panel, as ML charges an outrageous sum for new ones. But they can be re-conditioned MUCH cheaper...

 

[ChrisP]

Thanks Tosh, much appreciated

A fair point about 20 year old speakers needing some technical tlc if nothing else

When you talk about squeezing the panel, whereabouts do you mean?
One place in particular,
or just keep squeezing at various points working my way up the panel, listening as I go along?

Where do I squeeze across the width of the panel?
On one particular side or in the middle, or anywhere in particular?
Do I need to remove the side rails to do this?

Thanks again. I'm not averse to opening them up and investigating. I'll go and have a play.

 

[edwinr]

Driver or panel replacement is always a possibility with any 20 year old speaker because most times you don't know how the speaker has been mistreated. Hopefully not in your case. The Aerius is a nice speaker. If panel replacement is required, I reckon that would be a good option until you can afford Summits.

 

[Gordon Gray]

Chris,

The Aerius was my second ML. The CLS2A being the first. Followed by the SL3 and then the Summit.

Carefully check all speaker measurements. This includes azimuth angle.

Not ruling out a hardware failure but you must recognize "accurate" placement of both speakers (read the same down to 1/16") can have a profound effect on what you hear.

Good luck.

GG

 

[Tosh]

Thanks Tosh, much appreciated

A fair point about 20 year old speakers needing some technical tlc if nothing else

When you talk about squeezing the panel, whereabouts do you mean?
One place in particular,
or just keep squeezing at various points working my way up the panel, listening as I go along?

Where do I squeeze across the width of the panel?
On one particular side or in the middle, or anywhere in particular?
Do I need to remove the side rails to do this?

Thanks again. I'm not averse to opening them up and investigating. I'll go and have a play.

Chris,
At this stage (without removing the rails, and now that you have thoroughly vacuumed the panels) we are trying to discover if/why one ESL diaphragm is not holding a full HV charge, either by a bad contact from the copper strip to the diaphragm, or by excess leakage to a stator.

Leakage of the HV bias can happen anywhere there is a bridge (usually dust build-up, or the dead ant I found on mine!) from the diaphragm to a front or rear stator, but it is most likely to happen at the top surfaces of the horizontal spacers where dust settles (and with time and humidity turns into a conductive grime) and along the outside edges. So you will be squeezing everywhere, and in particular along the one vertical edge (right side on Aerius, IIRC) where the soldered connections enter. So far, you will not need to remove the rails.

 

[Tosh]

It seems to me that the imbalance seems slightly bigger as the speakers first self-power up for a couple of minutes, hence my question about the music sense circuit

Also, could you clarify this?

 

[ChrisP]

...I reckon that would be a good option until you can afford Summits.

Hmmm... yes Summits are my objective but I'm not sure if I'll ever quite afford them - the $ to £ conversion doesn't work well for us once the speakers have travelled over the pond. Hence the Ascent i being readily within financial reach. An for the future I've a great desire to drive them actively

The Aerius was my second ML. The CLS2A being the first. Followed by the SL3 and then the Summit.

Carefully check all speaker measurements. This includes azimuth angle.

Not ruling out a hardware failure but you must recognize "accurate" placement of both speakers (read the same down to 1/16") can have a profound effect on what you hear.

Good luck.

GG

Understood. Thanks

Chris,
At this stage (without removing the rails, and now that you have thoroughly vacuumed the panels) we are trying to discover if/why one ESL diaphragm is not holding a full HV charge, either by a bad contact from the copper strip to the diaphragm, or by excess leakage to a stator.

Leakage of the HV bias can happen anywhere there is a bridge (usually dust build-up, or the dead ant I found on mine!) from the diaphragm to a front or rear stator, but it is most likely to happen at the top surfaces of the horizontal spacers where dust settles (and with time and humidity turns into a conductive grime) and along the outside edges. So you will be squeezing everywhere, and in particular along the one vertical edge (right side on Aerius, IIRC) where the soldered connections enter. So far, you will not need to remove the rails.

Thanks for that - I understand what to do. Not had a chance to play with them yet. The weather has been unexpectedly good over the last few days and my time has mostly been spent gardening

It seems to me that the imbalance seems slightly bigger as the speakers first self-power up for a couple of minutes, hence my question about the music sense circuit

Also, could you clarify this?

I haven't noticed the effect so much recently, but when I first got the speakers home, turned them on and put music through them there seemed to be a 7-8dB imbalance between the two speakers (I had to set the balance control to 7 or 8 dB to correct the imbalance). The imbalance became smaller after the speakers had been on for some time. Now I've got the balance control permanently set to 2dB