Q&A with David Allen of ML. You asked the questions.. Here are the answers.

[TomDac]

Hey all,

Here's a Word document with the questions and answers from my conversation with David Allen of ML.

Also an MP3 file of Joe Vojtko pronouncing his name.

 

[Craig]

You guys had some excellent questions and thanks David for taking the time to answer them. I'm now more intriqued to hear a set of CLXs and it good to know there will be an upgrade option for my Summits although I did think they really needed one but it can always be better..

 

[JonFo]

Tom thanks for asking the questions and editing the response doc.

And thanks to Dave Allen for his replies.

The suggestion of a MLOC visit to Kansas in '09 is a great one. Count me in.

 

[marck]

I too agree that it is good news re Summit upgrade. Did he give you any indication of the cost and when it will be available?

Thanks
Marc

 

[TomDac]

I too agree that it is good news re Summit upgrade. Did he give you any indication of the cost and when it will be available?

Thanks
Marc

He did not, but I heard from the guys at the CLX west coast debut, that it will be $1500... not sure where they heard that from.... could be bunk.. could be true... dunno.

 

[JohnLomnicki]

Thanks

Thanks for the time you spent on this Tom.

Now I have an upgrade path from my Vistas

Stuff like this makes me want to become a true audiophile again.

 

[marck]

He did not, but I heard from the guys at the CLX west coast debut, that it will be $1500... not sure where they heard that from.... could be bunk.. could be true... dunno.

Cheers Tom. Mind you for us in the UK that means it will be £1500

 

[MotorToad]

So the bass panels are bipole and the regular panels are (obviously) dipole. I'm thinking that the bass response being so much better to the ears than the specifications suggest might have a lot to do with room interaction. My initial thoughts are that bipole bass panels probably interact better with the upper frequencies' reflections than a fully dipole panel that reproduced the same frequencies.

I suspected that they were bipole when I saw it was three stators and two diaphragms, but I wasn't going to assume. Nothing else made sense, but swapping the phase of the rear wave seemed odd to me. Perhaps that oddity is the secret to the speaker, though.

 

[amey01]

Thanks for the answers - very intresting!

One question remains unanswered......why no "airframe" on the CLX? Are you likely to speak with ML again?

Summer '09 get-together sounds brilliant - I'll definitely be attempting to come over for that one!

 

[C.A.P]

Ill be in Seattle the 10 and 11 Ill have to find out where they are going to be at. I love the placement chart. It goes along with what I have been saying for years . You must sit back 2 times the width of the inside edges of the panels . It works well, as long as you don't pin your self against a rear wall.

Good info!

 

[Jeff Zaret]

He did not, but I heard from the guys at the CLX west coast debut, that it will be $1500... not sure where they heard that from.... could be bunk.. could be true... dunno.

Tom,
I was told by Peter S and Harvey who is the NW rep for ML.

Jeff

 

[Jeff Zaret]

I want to reiterate what Tom, Dave and myself have said about the bass in the CLX. Even though the spec does no go down to 30Hz for some I would not be too concerned. With room loading I believe it will be close. I think the only situation where you would need a sub with the CLX is for LFE in home theater applications. I be willing to guess that the "CLX" setting on the Depth I and the Decent i are probably around 30Hz.

Believe me I love bass not rumble but well defined low end whether it is from a double bass (stand up bass), electric bass guitar or a pipe organ. The low end on the CLX was well defined and you did not feel it was lacking anything in the bottom end.

Just my 3 cents (inflation).


Jeff

 

[JonFo]

So the bass panels are bipole and the regular panels are (obviously) dipole. I'm thinking that the bass response being so much better to the ears than the specifications suggest might have a lot to do with room interaction. My initial thoughts are that bipole bass panels probably interact better with the upper frequencies' reflections than a fully dipole panel that reproduced the same frequencies.

I suspected that they were bipole when I saw it was three stators and two diaphragms, but I wasn't going to assume. Nothing else made sense, but swapping the phase of the rear wave seemed odd to me. Perhaps that oddity is the secret to the speaker, though.

I don't think they are bipoles, as that would imply the radiate out of phase, which would imply the diaphragms are compressing and expanding the air trapped between them, something that is not really feasible.

I’ll be posting a new thread on the dualforce ESL driver this weekend, as I believe I’ve figured it out and will have diagrams and such. I could be wrong of course, been so before

 

[Ron]

Tom,
I was told by Peter S and Harvey who is the NW rep for ML.

Jeff

There is no garentee they will have a crossover upgrade for the summits. The new crossover fits in the summit x. Our summit components are a little different inside. They will be trying to work something out, that will fit in the space. The price that was mentioned was just to give us a rough idea of the cost.

 

[MotorToad]

I don't think they are bipoles, as that would imply the radiate out of phase, which would imply the diaphragms are compressing and expanding the air trapped between them, something that is not really feasible.

I’ll be posting a new thread on the dualforce ESL driver weekend, as I believe I’ve figured it out and will have diagrams and such. I could be wrong of course, been so before

"The two outside stators are connected at low voltage potential. The center stator is driven by audio voltage. The two diaphragms are charged opposite of each other, one positive and one negative."

There's no other way about it, they're bipolar.

 

[amey01]

"The two outside stators are connected at low voltage potential. The center stator is driven by audio voltage. The two diaphragms are charged opposite of each other, one positive and one negative."

There's no other way about it, they're bipolar.

Bipolar is what a regular double-stator is, right? That is what I understand the CLX to be from that definition - if the two membranes are charged opposite, then as one is pushed away from the centre stator, the other is attracted. That is not compressing or expanding air between them - simply keeping a constant air pressure. Maybe I'm missing something major?

 

[JonFo]

Bipolar is what a regular double-stator is, right? That is what I understand the CLX to be from that definition - if the two membranes are charged opposite, then as one is pushed away from the centre stator, the other is attracted. That is not compressing or expanding air between them - simply keeping a constant air pressure. Maybe I'm missing something major?

OK, some terminology clarification seems to be in order to make sure we’re all talking about the same thing.

Bipolar speakers and bipolar radiation patterns mean that a speaker radiates sound both front and back. The usual configuration is to have the drivers (typical dynamic drivers that is) wired in phase, but one set oriented to the front, the other towards the back. This means all the sound radiated from the speaker is in-phase, front and rear. This will provide increased bass output, as the rear wave and front wave encounter is in-phase (but time delayed by the size of the cabinet, so some interference).

Dipole speakers, are usually a single driver element (like an open back dynamic speaker, or the usual ESL single diaphragm panel) that radiates it’s energy out of phase (when the front is pushing out, the rear is going in as it’s a single surface) http://en.wikipedia.org/wiki/Dipole_speaker

Bottom line:
Bipolar - in phase radiation
Dipolar - out of phase radiation

Regular ESL panel - is a Dipole, radiating out of phase
DualForce triple-stator ESL - ???

They could have configured the triple stack as a bipole, but air compression and all the usual negatives of an acoustic suspension alignment would be there. I seriously doubt that’s what they did.

So it must be a dipole (like the other ESL component), just with much more excursion and energized surface (since it has 2x the diaphragm surface to attract/repel).
The other clue that it’s a dipole is the ‘wing’ on the rear, which has been described as necessary for managing the rear wave. Hum, where have I heard about that before

So Amey, you are thinking about the correct motion (both diaphragms in synch) but that’s called a dipole due to front and rears being out of phase relative to each other.

 

[User211]

Excellent post, JonFo, I agree with your assertions entirely.

I guess the question is, what does this dipole dual force arrangement actually provide in terms of advantages? On a "forward push" towards the listener, he will surely only hear the results of the mylar diaphragm closest to him. So what is the following diaphragm actually doing? Given that air doesn't compress that easily, and "if" there is an airtight gap between the two, I expect it allows greater overall excursions and hence volume and lower frequency reach.

Anyone have any thoughts on this? Particularly the airtight gap? I am just sitting here guessing, really. Beyond all the hyperbole surely this is just the relatively simple arrangement as described above? Or am I wrong?

Justin

 

[User211]

In other words, we have effectively increased the mass of the diaphragm by driving the air with a sandwich of mylar/air/mylar...

Therefore, are we losing the very advantages that we gained by using a single mylar film. But then at bass frequencies, this doesn't matter as much...

 

[MotorToad]

The outer two stators are at the same voltage, and the center stator is signal. There is simply no question that the two diaphragms are driven in opposite directions.

The quote (repeated) is from ML: "The two outside stators are connected at low voltage potential. The center stator is driven by audio voltage. The two diaphragms are charged opposite of each other, one positive and one negative."

|<--|-->|
[n]d[+]d[n]


It's bipolar. That's all it can possibly be. The only remaining question to me is where the air volume between the diaphragms comes from and goes to. I'd expect it's more like a ported volume than an acoustic suspension design. Tuning the "port" frequency might be more difficult, but it'd be the easiest way to extend the bass frequency and efficiency.