[zygadr]

Well all, ..................here are the latest results using new panel material and different exciter configuration.

Yesterday, I picked up some 3mm plywood from the local timber supplier. The plywood was labelled ''Premium''........whatever that means?

The sheet size was an odd 1200mm X 820mm.

I attached the four exciters as I said I would according to the Amina loudspeakers photo previously posted.
3M adhesive tape used for all experiments was once again used in this new placement of the exciters.

I listened to digital radio broadcasts of classical music and jazz.

Result?...................WOW!!!!!!!!

The midrange is to die for..............highs are like silk and very pure and definately not lacking.
Now, here's where I was surprised............BASS :..........I have plenty, all the way down to about 50hz.
It is definately not one note and by feeling the panel, there is considerable vibrational forces at work with 4 exciters in the new position at the rear of the panel.

All in all, this sound from the thin plywood is without doubt the finest and best of all panel materials tried.
I'm not sure if the close together/offset exciter placement has something to do with this ?.......it may, or it may not?

The output from the plywood panel is noticeably lower than EPS, but the improvement in sound is well worth the trade off.

If the Monacor exciter turns out to be a winner, I think we have a stunning panel speaker about to emerge!!!

[pol_bct]

Understand. And how boundaries you use, means, borders constrained or free ? Here I read divergences from others users.

Waiting for the exciters to arrive and I will try plywood but thinner, 2 mm I think.

the less suspensions on boudaries you use, the lower resonance frequency you get, this is a good thing, unless you try to get advantage of a broad resonance around the cutoff of the tranducers/panel, but I would call this a "bad trick".

Thin plywood may be one of the best choices, I use two x 3mm x 1.25m² in one of my systems and I like them very much.

POL

[Abelma]

G

[Abelma]

[

[pol_bct]

Hi Pol,

It is possible that if the borders are free to move, some increased more distorsion could happen?
I am not sure, but when the corners cuted to 45 degrees the sound was more pleasant. I am wonder if with the borders somewhat attached with soft constraint will improve teh sound quality with less distorsion?

Hi
i think that cutting or rounding corners is one thing,  and doing a suspension is an other thing, like having the panel lying on the ground may be a third aspect of the whole problem.

POL

[doug s.]

Well all, ..................here are the latest results using new panel material and different exciter configuration.

Yesterday, I picked up some 3mm plywood from the local timber supplier. The plywood was labelled ''Premium''........whatever that means?

The sheet size was an odd 1200mm X 820mm.

I attached the four exciters as I said I would according to the Amina loudspeakers photo previously posted.
3M adhesive tape used for all experiments was once again used in this new placement of the exciters.

I listened to digital radio broadcasts of classical music and jazz.

Result?...................WOW!!!!!!!!

The midrange is to die for..............highs are like silk and very pure and definately not lacking.
Now, here's where I was surprised............BASS :..........I have plenty, all the way down to about 50hz.
It is definately not one note and by feeling the panel, there is considerable vibrational forces at work with 4 exciters in the new position at the rear of the panel.

All in all, this sound from the thin plywood is without doubt the finest and best of all panel materials tried.
I'm not sure if the close together/offset exciter placement has something to do with this ?.......it may, or it may not?

The output from the plywood panel is noticeably lower than EPS, but the improvement in sound is well worth the trade off.

If the Monacor exciter turns out to be a winner, I think we have a stunning panel speaker about to emerge!!!

now, you need to mount exciters in the typical wertical ewenly spaced arrangement, so it's an apples-to-apples comparison.   

great work, btw,

doug s.

[zygadr]

The exciters are free mounted as you say. This lowers the overall resonant frequency of the panel.
I don't think that this latest panel, which is more square than my others in the past makes any real difference at all.

I have noticed however that lifting and holding the panel off the ground by the top corners, instead of just letting them stand upright on the floor, does improve the sound.

Ideally these plywood panels should be suspended by their corners by the looks of things?

Hi doug s. ..........I don't think I'll bother with the in-line exciter placement.
Reason is, I believe we are entering NXT's DML modelling software for exciter placement rather than Podium Loudspeakers hybrid that has been the norm in the past.

[tino84]

ok.

DON'T BUY from lieske-elektronik.
I wrote them an e-mail last week (with no answer).
I wrote them this morning to know if my order has been shipped (they told me it would had been delivered last week).

well,now AR-50 are out of order,until next week! (but when I ordered,it were 2-5 days to have it.)
And no e-mail to advise! I had to write to know! quite a month 

I'll ask a refund

[scorpion]

I checked  Monacor's own web site. It seems that the AR-50 is on a wait list but the AR-30 is available,

/Erling

[zygadr]

Hi Erling!.......good to hear from you again mate!

Thanks for the info on the Monacors. I guess we have a little longer to wait before these are readily available.

I t is interesting though that these are on a wait list (sold out?) . This may be a good indicator that they work very well?.............maybe?

[Abelma]

-

[zygadr]

Let us know how the Visatons go Abelma

This ''forward thinking'' towards more powerful and rugged, better made exciters is important as you will note on my next observation :

The standard cheap exciters sound good when freely mounted but I have observed that over the long period of time that I have had them (as long as this thread!!!) they are exhibiting ''VOICE COIL DROOP''.
In other words, the weight of the magnet under gravity is pulling the voice coil downwards and will eventually affect performance...............DAMN!!!

For those who wish to use this type of exciter, my suggestion is to consider siliconing the back of the exciter to a frame of some sort so that it will be supported against gravitational forces.

[j gale]

Re: voice coil droop.  If the exciters are to be placed near centre NXT style it would be easy to rig your panel to be turned upside down periodically. Even with exciters in a vertical row all it takes is longer wire. Say, once  a month flip it the other way and let it stay that way for a month and then flip it back for another month. I have been flipping mine for awhile now. Seems to work.

[zygadr]

  ............I've also been doing that 
Unfortunately, on the type of exciter I have (and there were a couple of minor variations in the Parts Express/Dayton line up), the corrugated spider is a bit larger than the others and eventually goes a bit soft.
I may try some model aeroplane dope on it to see if that helps?

Anyhow, the plywood panels still amaze me at their superb fidelity and extended top end........who would have thought????
The panel really sounds like a giant omnidirectional sound source.........FULL RANGE too!!!

[Abelma]

-

[pol_bct]

I would like to connect four per pannel. The exciters are 8 ohm and now they are connected in parallel having 4 ohm at the end. With four which is the best way? Series and then parallel, or parallel then series?? In both cases I will have 8 ohm at the end.

I suggest you do serie THEN parallel,
I already tried with a lot of loudspeakers  (2x25)
http://pol.bct.pagesperso-orange.fr/exemples/Naos2.jpg
the sound is not the same, though impedance is still 8 ohms

POL

[zygadr]

The way I have allways connected 4 exciters is : two sets paralelled, then the sets series connected = 8 ohms.

[Abelma]

Hi Pol , Zygadr..
Can you explain me please why one way is better than the other? Is confusing having two opposite opinions 

[tino84]

reminder, don't waste your time with lieske-elektronik.de

they didn't offer a refund,and they don't answer to e-mails to know when will monacor arrive,or if can give back your money. (I remember that Directive 97/7/EC provides a refund if items are not available)

I had to open a claim with Paypal (yesterday,still no answes..),we will see..

Meanwhile,you're better STAY AWAY from them

[zygadr]

Geez tino84!..........you have really had bad luck I'm sorry to say. Hope you get your money back!

Abelma, if you do paralell first, you have 3db gain from lowered impedance and the extra exciter that is joined to it.......total of 6db for ONE SET.
Remember that you still have the other two in a 4 exciter system, so that's 12db increase overall in sensitivity.
The series connection of the two sets just bring it back to 8 ohms but does not increase or affect sensitivity.
So, yes, if you do it the other way, there will be a difference in sound.

As we are only dealing with 4 exciters this is up to you which way you wire it.
If it were many drivers such as a line array,depending on the number of drivers, you will be forced to wire a certain way to reach your desired impedance.