ESL in infinite baffle


You might get away with it, but you will need to re-EQ the speaker to de-emphasize whatever mechanism ML used to compensate for dipole cancellation (which won't be a factor anymore) -- could be a hi-Q resonance, bass EQ, or a combo. Be aware that if you make the IB air tight, the possibility exists that a slammed door or home theater subwoofer pressurizing of the room could cause the ESL diaphragm to hit the stators despite a lack of input signal.

Please let us know how your experiment works out.

Thank you for answer,

So you think that it will be not so linear in the low frequencies or in all the range? Normally the ML monolith is cut in the 100Hz region, I hope in IB it can go lower.

For instance I didn't unmounted the ML so I don't know what EQ they have done on it but do you think that the xformer is enough good to work fullrange? And if I have to change it which one can I use, I've seen that sowter makes some good xformer for esl that can go to 40Hz but which one to use : 1/40, 1/60, is 50W enough???? I'm very not expert with ESL.

There will be a dipole bass roll-off below a frequency range determined by the dimensions of the un-baffled panel. I think that it ultimately becomes 6dB/octave and has been compensated for -- at least for the full-range ESLs.

Here is a link you might find helpful:

Linkwitz designs dynamic dipole speakers, but the physical principles are the same.

the monolith panel was designed to fullfill the requirements for an hybrid system, in which a dynamic woofer takes care about low frequencies. So its not a "Woofer-Panel".

Most acoustat elements are designed fpr fullrange, means they can perform down to 30 Hz, but sensitivity and maxpressure is significantly lower than the monolith panel. But there are acoustatpanels for hybrids as well

Soundlab wwere/are meade for different purposes. there are fullrange panels and hybrid panels as well.

As you are unexperienced, please consider my advise:
Take the monolith panels for what they are designed for, means run them down to 100Hz by using an active crossover and combine them with high sofisticated woofers. You might even try ready to run subwoofers (velodyne.....), since the have amps and active filtering integrated. Doing so, your system will run soon and perform well.

The IB should be better than a dipole ESL, imho.

Assuming proper mounting, and no rear reflectons...

The Monolith's weakness was not so good bass.
Ought to be pretty easy to replace the woofers with far better modern drivers - select for proper roll-in and flatness of response, plus better Xmax and Fs/VAS/Qt values than the originals. With a biamp set up the relative efficiency of the new woofers is irrelevant.

You'll likely need some sort of bottom end - but again an IB will work nicely - with just the ESLs being run IB.

I'd test them IB and see what they do, then measure, then decide on the woofers.

Try to set the mechanical position of the woofers so that they give the best impulse response measured at the listening position.

Also, you'll need to experiment with the height of the ESL cells, the height above ground will effect the response somewhere in the ~100Hz. range (floor dip cancellation).

Maybe I can help, as I have both Monoliths and an IB sub...

First, even the big Monolith panels are not that great under 200hz, even brand spanking new panels I just got in '06, are not flat to 110.

I refurbished my Monoliths several times in the past decade, upgrading woofers twice, and ditching the factory passives and running active Crossovers (DriveRack 260’s)

Here’s the thread on the Monolith woofer updates, plenty of pics and measurements in there.

As for Sub integration, even though IB’s are very, very clean, I’d not cross over any higher than 100hz to 15” drivers. I keep my highest LP at 80Hz, with the Monolith woofer crossing over to the sub at 60Hz.

So I think you still need to address the woofer. But it’s very easy, just follow the guidelines I lay out in the thread above. (assuming you have active Crossovers).