[-Richard-]

I agree with you Occam...in the spirit of your insights one could design an OB
from the ground up more effectively than from the main driver downward...
at least in theory...and the greater choices in drivers makes things much more
interesting...and allows for a greater amount of control over sound aesthetics...

Your irony of using the Alon speaker with its OB dipole design which is 17
years old is not lost on me...I should reorganize my thinking here...it is not the
design of dipole OB pistonic drivers that is new...as you wryly point out...

It is rather the idea that we have been conditioned to believe that the magic
we are looking for in reproduced sound comes in expensive boxes that
have been created with vodoo science and complicated computer programs
that calculate secret interior dimensions...when in effect sticking a driver in
a plank of plywood with a hole cut out gets you very close to a "real" and "live"
musical experience that almost all conventional speaker designs fail to do...
no matter what they cost...or the hype that surrounds them...

That is new...in the sense of a new awareness of what is possible...and for
very very cheap...and one could actually create it for oneself with a
minimum of skills...

Why your Alons did not in-and-by-themselves create the revolution in awareness
of the strengths of OB dipole configuration for pistonic drivers may have
more to do with the nature of how things become adopted and understood
in historical terms...and there are many theories that try to explain such
phenomenon...

It may just be that the present "movement" is based on an inexpensive approach
to simple designs...thanks in large part to how DMason presented it in the first
place...strongly suggesting we all jump into experimenting for ourselves...
as opposed to your very subtle and sophisticated Alon driver which perhaps
still gives off the image of an "untouchable" technology...at least by the likes of
me...with my rudimentary knowledge of carpentry and building skills...

Thanks for your insights, Occam, as always...

Warm Regards -Richard-

[Occam]

Actually, the Alons are 'Jonnie come latelys'. Gilbert Briggs designed a dynamic transducer dipole (on a sand filled sandwich baffle) for Wharfdale in the mid-late 50's. I think I may have heard them as wee lad, prompting my later interest, but then again, that might well be wishful thinking.....

[eric the red]

Actually, the Alons are 'Jonnie come latelys'. Gilbert Briggs designed a dynamic transducer dipole (on a sand filled sandwich baffle) for Wharfdale in the mid-late 50's. I think I may have heard them as wee lad, prompting my later interest, but then again, that might well be wishful thinking.....

Here you go Occam
http://www.audioasylum.com/audio/speakers/messages/214553.html

[Roger A. Modjeski]

Occam and all,

Thank you for you thoughts on the OB and sub project that Richard and I are working on. You have clearly stated the problem and I agree with your ideas. Given that the 2 woofers (lets call it a "sub+", shall we.) have to go higher than most subs, sit near the mid/tweeter driver, and be small as possible, we can now consider drivers that have higher fs and Qts. Can you suggest a few? They would have to be good to 300 Hz and have high sensitivity for our low power SET amps. I am a bit out of touch with the wide selection of drivers these days.

I remind all of you out there that a  bipolar "sub+" cannot, by its nature, produce deep bass for the same reason as the OB; the front and back wave cancel at low frequences. We cannot make baffles big enough to suit them. Remember a 40 hz wave is 25 feet long.

To everyone: I would love to see your nominees for the extended midrange driver. Anyone tried the old AR-3A midrange driver? I happen to like it. Is anyone producing that?

roger

[FJK]

Some that come to mind just from what I have been able to compile from researching all the forums (please note I am just a layman and this is just what others have written about them) ,

EXPENSIVE
Lowther-great tone but a little lacking in freq extremes and may not play as loud as others. More popularly used  with horn loading.
AER-great but needs work to cure anomolies
Supravox-could be the best one
Fertin- Not enough owners to comment about them
Hartley- Even less owners than above  

MODERATE
Eminance-needs work as well
Fostex-great bang for the buck. Not the best but pretty good.
Beyma-needs work and not that popular
Visaton B200-needs work but has great potential

INEXPENSIVE
Ciare- great sound for  the price. Big hit in Europe right now.

SMALLER
Adire
CSS

I suppose the biggest question in selecting any of these is whether to use help below and above with additional drivers.  


(As for myself, I decided to buy the Bastanis Prometheus MK2 AF which uses a custom Eminance. I won't have for some time so can't comment on it).

[Russell Dawkins]

Three more:
two that really deserve to be on the list, when loud is not very important, are the Jordan JX 92S - a favorite of some very experienced professionals like Nelson Pass - see this extreme implementation:
http://www.passdiy.com/speakers.htm  (1/2 way down the page "J-Low")
and Junji Kimura chief designer at 47 Lab, who use this speaker as his reference:
http://www.sakurasystems.com/products/essence.html

and the new JXr 6XD (with extraordinary specs - check out the efficiency/diameter/moving mass/free air resonance figures - 88.9dB/2"/1.2gm/80Hz)
http://www.markaudio.com/speaker_jordan_2.php

Also for when loud is important, as well as deep, there is this new Silver Iris 15" mentioned here:
http://www.audiocircle.com/index.php?topic=24763&postdays=0&postorder=asc&start=0

[JLM]

Those new Jordans look interesting, but very expensive and very output limited.  Until I saw the price I was thinking they might work well if you used enough of them in a vertical array (if you're into that sort of thing).  And their efficiency doesn't match well with the small amps in this thread.

We have a good list to look at.  The shortcoming of many extended range drivers is in the attempt to use them as full range drivers, to push them too far, especially towards the bass end.  IMO whizzers are evil (unknown effects from an unsupported cone that blocks part of the wavefront of the main driver) and coaxial units are not single drivers (they may be the best compromise though).

[JoshK]

You guys might want to take a look at the black dahlias, if for nothing else that to see how someone else has done it.  They too use a full range (lowther) driver as an extended midrange driver supplemented with a ribbon up top and a huge pro sound woofer below.  

I think more inventive solutions to the woofer can be done that will lessen the footprint substantially.  I also see a problem potentially arrising in the power response of mixing a dipole mid with a monopole woofer.  The Iris look interesting but without more information on how they reach their quoted outcome it is hard to tell what they are doing.

[Occam]

....
I think more inventive solutions to the woofer can be done that will lessen the footprint substantially.  I also see a problem potentially arrising in the power response of mixing a dipole mid with a monopole woofer....

You're obviously right, but life is full of compromises. I'll simply point out that folks, for whatever reasons, do tend to like the Alon/Nola dipole midrange speakers, as well as the late, lamented Innersound products.

For rational costs, we're looking at high efficiency prosound drivers, and off the top of my head -
http://www.partsexpress.com/webpage.cfm?webpage_id=3&SO=2&&DID=7&CATID=49&ObjectGroup_ID=585
who carry the Galaxy 'full rangers' and the Eminence Alpha 6

and from US Speakers who carry many, many Prosound drivers such as Eminence, B&C, Beyma, Ciare....
http://www.usspeaker.com/homepage.htm
where you'll need to look at what they call 6-8" woofers to see such things as the B&C , Beyma and Eminence midrangers

or specific manufacturers and their reps such as the US rep for Ciare and their ceramic magnet drivers -
http://www.assistanceaudio.com/08_Ciare.html

FWIW

[JoshK]

You are absolutely right about life being full of compromises.  I dont know of any speaker that doesn't have some.  If you go dipole bass, you typically need to EQ, so pick your poison, EQ or power response transition.  

I still want to hear your Alons, I am sure they sound wonderful.

[TomekZ]

Also discovered open baffles lately and couldn't think of going back to a closed box--well with an open baffle the listening room is the speaker box, so still closed technically.

Tried the CSS125s and they work well in a small room. The Jordan JX92s did not go as deep when OBed, and sounded too bright. Presently, I mostly listen with the Fostex F200a. In my smallish room, these alnico Fostex at 90db/watt efficiency work well in an open baffle.

Certainly, I'd like to try other drivers, but am shy of using the high efficiency of the Visaton B200 or the Hawthorne. With high efficiency comes increased dynamic swing, which makes one want to listen louder in order to hear the quiet passages.

These days, I mostly listen with Wright Sound 2a3 SET.

[Manowar]

Read lots of good things about this PHY-HP KM-30 driver from France,
never heard it myself...looks nice ...quite expensive


http://phy-hp.com/English/Products/KM30_E.html

Thanks,
Manowar

[Russell Dawkins]

I gather the 8" PHY sounds a little better than the 12'. I know of one person who went from 12s to 8s.
For what it's worth, the FR on the 8s looks better, as does the impulse response. Apparently the favorite of the designer is the 8" silver vc, which also handles the least power - 15W vs 25W and 50W for the 8" copper and 12".

[-Richard-]

Technical specifications are no doubt of vital interest to anyone who is
trying to make a reasonable guess which driver...or for that matter which
amplifier...would render the most accurate signal from any source...

But I think measurements are only a reference point...designing strictly by
measurements will not necessarily yield the sound one may be looking for...

It is one thing to talk about "dynamic swings" as a theoretical construct...
but it quite another to imagine that those "words" which are abstractions in-and-by
themselves can actually be relied upon to translate into an accurate
sonic picture of what a speaker actually sounds like...

The B200's (and quite possibly the Silver Iris 15" coaxial) sound rather fabulous...
when I am listening to it in my simple OB what I hear is real music sounding more
alive and realistic than anything I have ever heard...and I have heard a great
number of speakers over the years...this one is special...although there are other
drivers out there they may be equal or perhaps better than it...in absolute terms...

Roger may feel quite otherwise about all of this because he feels very strongly
that his amplifiers, for example, should measure well on the test bench before
he considers other sonic attributes...a good place to start...a philosophy that
no doubt contributes to the success of his designs...

I am only pointing out that we are a society that is drenched in technical
mumbo jumbo which in many instances passes for reality...I am vigilant that
I do not let that infiltrate and define what my ears are hearing...

Leonardo understood that for our species...a human being is the measure of
all things...in a relative scale of the real...and in my world the senses do
not get placed in the background...

Science is mutable...the laws change with each generation...and devices for
measurement have the potential to become ever more sophisticated...

The problems arise out of sciences conceptual framework of the model...man...
it must organize what it is measuring as an absolute reference to that model...
and that is a work in progress...

Warm Regards -Richard-

[J North]

Occam and all,

Thank you for you thoughts on the OB and sub project that Richard and I are working on. You have clearly stated the problem and I agree with your ideas. Given that the 2 woofers (lets call it a "sub+", shall we.) have to go higher than most subs, sit near the mid/tweeter driver, and be small as possible, we can now consider drivers that have higher fs and Qts. Can you suggest a few? They would have to be good to 300 Hz and have high sensitivity for our low power SET amps. I am a bit out of ...

Roger,

A couple options for dipole 40hz to ~250hz:
1. The upcoming 15" bass driver from Hawthorne Audio. Not much info yet.

2.  2 or 4  Dayton RS265HF per side. You would have to go active XO & EQ and use SS amplification with these. Lot's of good info on this thread:

http://www.htguide.com/forum/showpost.php4?p=223116&postcount=333

That is what I am looking at doing for the bass. I would then have 2 dipole B200's per side in a 1.5 configuration. The ".5" would play 250 to 1000hz or so. Bass below 40hz would be monopole subs.

Hope that helps.

Any update on the new amp???

Thanks . . .