Single vs Multiple driver loudspeakers...

El: You should start studying Walsh "Bending Wave" technology. It doesn't suffer from all of the problems that most conventional dynamic drivers that you have described do. No whizzers yet you can get very reasonable high frequency extension, excellent horizontal dispersion, gobs of surface area for good low frequency extension, etc... Using this approach though, one is still limited in SPL range though.

As to more conventional designs, Nelson Pass' latest DIY speaker effort is published in AudioXpress this month. Making use of a Lowther DX55 in each HUGE and highly technical cabinet, the results are staggeringly non-linear and completely lacking in bass. After applying equalization circuitry and running a completely out of the ordinary amplifier design that is the reverse of what is commonly bought and used, the end response doesn't look bad at all. The fact that it took someone like Nelson Pass, a huge cabinet, custom built electronics and this much work to get the speakers to flatten out says gobs about where this type of driver is at in the grander scheme of things. Sean
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Sean...I did learn about the Walsh driver when the original Ohm speakers were introduced, and was very greatly impressed by the sound. I could not afford them then. Their ability to reproduce a squarewave, proven by scope photos, was remarkable, although some have said that a few other speakers can do this (but I never saw their scope photos).

I do have a soft spot for FR speakers, since that's what got me going in Hi Fi. I really wish that I still had that old Wharfedale 8" with cast frame, huge magnet, and floppy flannel cloth surround. I bet it would compete with the best there is today.

As to the N Pass effort...I agree that it seems that a great deal of effort went into making the driver do a task for which it is unsuited. There are forms of music where a little FR driver is ideal. Why not use it for that music, and give it a rest when you want to play a Sousa march?

Nelson is now marketing limited edition products specifically suited to the FR ( Lowther / Fostex ) crowd. As such, this was not only "research" for his products, but also the chance to have some fun and experiment at the same time for him. As you know, he's more of an "electronics man" than a "speaker man", so i'm sure it was a nice change of pace for him. The fact that he'll end up making money derived from the research and results that came out of this "fun time" probably doesn't hurt him either : ) Sean
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I was just on the Lowther America website, and they have the new Pass stuff on there.

One thing that interested me was a quote from Nelson Pass, saying,"This is the best speaker that I've ever heard".

Now if you ask me, I'd say that when respected SS amp makers are getting into Lowthers, then the single-driver market is starting to get somewhere. It has always actually "been there", but it took quite a while to get some more widespread acceptance.

Sean and Eldartford, you guys need to listen to some of this stuff. You may be quite amazed what a couple millimeters of Xmax from an 8" driver can do with 2 watts input. I'm currently filling my room(24'long, 14' wide, 16' vaulted ceiling) with my pair of Lowthers and my 2 watt SET, and it is LOUD, and it does quite well down to 40Hz, really. I can hear it out in the yard with all the windows closed, when I walk the dog. There is more to this than meets the eye.

Twl: I've heard Lowther's, but not to any great extent. I've also read the entire article that Nelson published. I've seen the response curves and have at least a decent idea of what it took to get that driver to do what it is doing. I can pretty much guarantee that there's nobody other than Nelson Pass in the entire world that is getting that type of response out of those drivers. That is, unless there's someone else out there using similar equalization circuitry and an amp that has an output impedance that is appr EIGHTY ohms.

Even with all of that and a horn mouth that is 5 feet wide and 6 feet tall connected to a cabinet body that is 9.75' tall and 4.5' deep, the speaker is still -3 dB down at appr 48 or 49 Hz. In Nelson's own words "I have been extremely pleased with the results, but i must smile when i see that all of this effort barely gets us below 50 Hz".

Other than that, i have 104 dB horns and have driven them with as much as 400 wpc SS and 35+ wpc tube. Two watts isn't enough power for a speaker, even at that efficiency level. That's because 104 dB's @ 1 meter becomes appr 95 dB's at a 10' listening distance. While this is pretty loud for most people, it is nowhere near the levels that one hears at a live orchestral performance if sitting reasonably close to the performers. This is not to mention a live jazz, blues or rock show either.

Besides the spl levels, with only 2 watts, one is pretty much guaranteed to run the amp into compression and clipping on a regular basis. On top of that, feeding that much steady state power into an excursion limited Lowther is going to create dynamic compression and introduce other forms of distortion into the equation. This is why, even though he had a GIANT horn doing all the work and keeping the driver properly damped and loaded at low frequencies, Nelson Pass stated "Still, they play loud cleanly in a manner that Lowther owners don't usually encounter, and the cones are barely moving". Without the aid of a horn this size, there is just no way that the Lowther can produce ANY type of bass and / or high spl at the same time.

As a side note, Nelson provided the readings as taken from a Lowther in a standard sealed box. Using the output at 1 KHz as a reference point ( industry standard ), this driver is down appr -15 dB's at 100 Hz. By the time we get to 40 Hz, we are down almost -30 dB's. That's why he couldn't squeeze ANY deep bass out of the driver, even in that phenomenally LONG and HUGE horn.

Needless to say, i DO like some of the advantages of a single driver, but i also realize that, at least at this point in time, none of them do everything well. If you want extension, you give up efficiency. If you want efficiency, you give up extension. They are all a trade-off, some to a greater extent than another. Sean
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