Beyond the Ariel

[Lynn Olson]

Now that I think on it a bit more, the only real gain for the front&rear symmetric horns are a dipole polar pattern. However, in terms of standing waves and pipe modes, the length of the horn is doubled, although perhaps an argument could be made the termination on the rear portion is gentler with a front&rear symmetric horn than a closed chamber or open-back loudspeaker. An arcane point like this could only be determined by finite-element simulation and a direct time-domain measurement.

[CV]

Hi Lynn,
What you say about the air loads being in series as far as the driver is concerned makes perfect sense, many thanks for that concise explanation.

There may be a higher order effect here: if the driver (be it an ESL or paper cone) is acoustically transparent, does a reflected wave not see an abrupt radiation impedance change - generating more reflections? Is that what you were getting at with the second part of your reply?

Thanks again for a great thread... seeing if I have enough pennies to go for the double RAAL...

Best wishes,
cv

[dhobson]

SunRa:

The peerles mids are way to insensitive. Why not take a look at audax pr170m0, 97dB listed at madisound for the same price? Or maybe one of the beyma 6MI90 (realy cheap), 605ND (not too expensive) , B&C 6PEV13 or 18sound mids discoused here or on magnetar's thread. The price should be quite similar to the peerles.

edit: regarding bass... I think I'd better go with some 15" eminence woofers. They have a higher qts, and a spl of about 98dB. For the price they will probably outperform the selenium drivers.

Magnetar:

I agree with all of this... If only using 2 woofers a side use 15's - !
The Audax is probably the best if no horn/WG is used. A pair a side is very good
The little 18 sound horn is very good, and so is the little B&C DE10 driver (treble)
This should be a killer OB system - probably will need a sub for the lowest bass otherwise you could probably do no better for the $$$, it will shame most high end systems if you get the crossovers right

Sorry I probably should have clarified that the number of drivers I listed was per side and so total number is X2. I took your advice and will try to get a hold of 4, 18 sound mids but will keep the selenium woofers as they conform to my design parameters and think about a sub addition later, thanks for your help, I will update my progress once I get a hold of the drivers and can start measuring and testing

[john k...]

It is correct to say that the radiation impedance for both sides of the driver is in series with the driver. This will influence the velocity of the diaphragm or cone. However, the SPL radiated from the form or rear side will be the radiation impedance times the cone velocity. If the radiation impedance is not symmetrical, the SPL will be different front and rear. An undamped u-frame is a simple example. As shown in this measurement, the front and rear SPL is quite different.


The rather "normal" looking front SPL indicates is that for the woofer in this system the significant difference is radiation impedance (primarily the mass reactance) between front and rear has a small effect on the cone velocity compared to the mass of the cone. If an ELS diaphragm (or other low mass diaphragm) were substituted the low mass of the diaphragm relative to the mass reactance of the air loads would significantly affect the diaphragm motion, reducing its velocity at the u-frame resonance with the consequence that the peak in the rear response would be diminished and the front response would develop a corresponding dip.

The same arguments apply for front and/or rear wave guides/horns. If the front and rear are loaded differently then while the radiation impedance from front and rear are in series with the "driver" and will combined to influence the driver motion, the front and rear radiated SPL will depend only on the resulting driver motion and the front or rear radiation impedance, respectively.

[SunRa]

Sorry I probably should have clarified that the number of drivers I listed was per side and so total number is X2. I took your advice and will try to get a hold of 4, 18 sound mids but will keep the selenium woofers as they conform to my design parameters and think about a sub addition later, thanks for your help, I will update my progress once I get a hold of the drivers and can start measuring and testing

I'm still concerned for the low Qts of the selenium drivers. But beeing 4 of them per side, you may use a small amount of EQ if nedeed.

[pdan]

Categorical Chains

When designing loudspeakers it is so easy to become category bound and pass quick judgement, forgetting that each of the categories are transformations of themselves. For instance: we may think "horns are bad", whereas a simple flat baffle is a horn, drivers too, are horns. So a multi driver OB is a complex horn system.

Lynn talks of doubling up the cone area per octave to compensate for baffle loss. If we see WG's as efficient couplers then we may find a trick or two. A single 12" driver mounted in a 24" diameter WG will have four times more radiating power than a single 12" unit.


Cilla

[Magnetar]

Originally posted by pdan
Categorical Chains

Lynn talks of doubling up the cone area per octave to compensate for baffle loss. If we see WG's as efficient couplers then we may find a trick or two. A single 12" driver mounted in a 24" diameter WG will have four times more radiating power than a single 12" unit.


Cilla

No such trick exists in this galaxy. If you want the bass to be more efficient use a real horn or more drivers. Sure it will radiate more but only in the midrange, unless of course you don't mind the 'WG' to be 3-4 feet deep

[pdan]

What I had in mind was using a 'WG' to reduce baffle loss.

Cilla

[SunRa]

I was thinking at magnetar's claim, about those 103dB needed for real-life dinamics. It apeared to me that this is posible just with horn loading or multiple drivers, like Mr.'s Olson last drawing. However, AER (the original one I think) makes a driver capable of 104dB and 10mm Xmax. The most expensive one is capable of 106dB.

The mesurments for the

AER MD2B (104dB)
AER MK1 (103dB) (the cheapest and maybe affordable one)
AER MD3 (106 dB.. I think I don't want to know the price for this one)

Here is a very interesting (12"?) bass driver that seems to have 101-102dB

[Magnetar]

Originally posted by SunRa
I was thinking at magnetar's claim, about those 103dB needed for real-life dinamics. It apeared to me that this is posible just with horn loading or multiple drivers, like Mr.'s Olson last drawing. However, AER (the original one I think) makes a driver capable of 104dB and 10mm Xmax. The most expensive one is capable of 106dB.

The mesurments for the

AER MD2B (104dB)
AER MK1 (103dB) (the cheapest and maybe affordable one)
AER MD3 (106 dB.. I think I don't want to know the price for this one)

Here is a very interesting (12"?) bass driver that seems to have 101-102dB

None of those are capable of that efficiency over a wide range without being horn loaded. They are like most of the drivers being discussed here - actual 93 to 98 db with 2.83 volts.

They are expensive because they are some of the best wide range drivers ever built - use them wide range and try to get them to sound live with or without a horn (both front and back loaded) you will have massive IM distortion when listening to music compared to a good 3 or 4 way multiamped system. The difference will be dramatic. Not to say the AERs won't satisfy the majority of listeners. In this case 'beyond the ariel' they would be expensive midrange drivers.

My claim is just that, my claim , my experience. Nothing but my opinion - after I have built several full range (20 to 16K) systems 96 db sensitive up I have a feel for what it takes to sound free from compression (for me!). When you listen to live music it's so dynamic and free from typical 'hifi' artifacts it makes most systems sound like a primitive tinker toy - I want it to sound the same where I am limited only by the recording.. it's not easy and it's not 'conventional' ..

It would probably be higher than 103 if I don't quad or penta amp. Once you live with a system like this - a beast - it's virtually impossible to go back to regular speakers. I tried a couple times and found only full range electrostats are worth pursuing - (compressed coherence!) except they suck when it comes to live, realistic reproduction BUT do sound a lot better than the typical high end cone aand domes you see in stereophile (I've had big dunlavy, focal, watt, fulton, infinities, ect..) LOL

I'm probably as odd as my claim! There aren't many folks that go where I go with this mainly cause they never experienced what it's like... or don't believe live reproduction is possible, or don't care, or.... well - list goes on and on. I'm the odd one - do what you find is right for you.

I have decided to quit participating in the 'beyond the Ariel' and sign off of this thread.

BYE!!