Not long ago, a young whipper-snapper berated me at this very forum for using old gear (and disparaging the eternal verities of sim programs).
As part of downsizing, I'm parting with an early (1955?) AR-1 (formerly with Pancake Altec driver in it... alas) that I bought used around 1965. Soooo, I thought I'd see how the woofer driver looked full-range on REW on my cheapie SLM at one meter, roughly 95dBC, while sitting in the middle of the floor. Lower curve is THD, about 40dB down and comparable to my other woofers as measured by my instruments, 1/12 octave, 10 dB between horizontal lines.
That should show that young whipper-snapper* what's old about correctly designed audio gear! (OK... I may have added a bit of goop to the cone 40 years ago in the spirit of DIYaudio.)
BTW, 1.4 cu foot sealed boxes don't look so bad, eh. Even if 60 years old.
There's a great New England speaker website called "Classic Speakers" of yesteryear.
Ben
*Is that how yer spell "whipper-snapper"?
As part of downsizing, I'm parting with an early (1955?) AR-1 (formerly with Pancake Altec driver in it... alas) that I bought used around 1965. Soooo, I thought I'd see how the woofer driver looked full-range on REW on my cheapie SLM at one meter, roughly 95dBC, while sitting in the middle of the floor. Lower curve is THD, about 40dB down and comparable to my other woofers as measured by my instruments, 1/12 octave, 10 dB between horizontal lines.
That should show that young whipper-snapper* what's old about correctly designed audio gear! (OK... I may have added a bit of goop to the cone 40 years ago in the spirit of DIYaudio.)
BTW, 1.4 cu foot sealed boxes don't look so bad, eh. Even if 60 years old.
There's a great New England speaker website called "Classic Speakers" of yesteryear.
Ben
*Is that how yer spell "whipper-snapper"?
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Ben,
I usually see whippersnapper written without a hyphen, but the spelling looks correct
.Your AR-1 response would probably look a lot smoother if measured near field, ground plane, hard to tell what floor bounce and room response are doing with the mic a meter above the driver, and the driver a foot (or so) off the floor.
The screen shot below is a circa 1961 AR, measured at 2 meters ground plane out doors (3 dB scale between horizontal lines), compared to your 1955 model.
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Thanks for spelling help, Art.
My 1940s Klipschorn decided it wanted to live in Montreal and left yesterday. Which left me a swell empty woofer corner and woofers abhor a vacuumed corner. Thought I'd update my Truly Ancient and Honourable AR-1W curves. Looking forward to learning observations of any whippersnapper.
My take on the pix: real-world room, mike at listening position. Big dip at 56 Hz shows up on every measurement I've ever made in that room. Distortion wonderfully low for an ancient driver and partly from objects bouncing around in the room.
This is one of the first series AR. The cone weight is great (and I've modified it a bit with silicone rubber). Totally unbendable pistonic cardboard. Usual resonance of this driver is said to be 12 Hz (where can I buy one today?) and in the 1.4 cu ft box, about 43 Hz. Isn't it weird that this woofer is doing so well to 2kHz?
Ben
My 1940s Klipschorn decided it wanted to live in Montreal and left yesterday. Which left me a swell empty woofer corner and woofers abhor a vacuumed corner. Thought I'd update my Truly Ancient and Honourable AR-1W curves. Looking forward to learning observations of any whippersnapper.
My take on the pix: real-world room, mike at listening position. Big dip at 56 Hz shows up on every measurement I've ever made in that room. Distortion wonderfully low for an ancient driver and partly from objects bouncing around in the room.
This is one of the first series AR. The cone weight is great (and I've modified it a bit with silicone rubber). Totally unbendable pistonic cardboard. Usual resonance of this driver is said to be 12 Hz (where can I buy one today?) and in the 1.4 cu ft box, about 43 Hz. Isn't it weird that this woofer is doing so well to 2kHz?
Ben
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are you sure fs is in the 12Hz region? here's something nabbed AR1 WOOFER REPAIR - Acoustic Research - The Classic Speaker Pages Discussion Forums
Villchur = Great thinker - all sensible, the AR turntable was about as good as more problematic "high end" tables I love Henry Kloss's stuff too.
it shouldn't be difficult to make woofers like that again - - but who does it?
Villchur = Great thinker - all sensible, the AR turntable was about as good as more problematic "high end" tables I love Henry Kloss's stuff too.
it shouldn't be difficult to make woofers like that again - - but who does it?
Wow - all that interest in 60 yr old drivers. Fs somewhere between 13 and 18. Weight 114 g. Thanks very much for the link.
Ummm, doubt there's an RJ forum. Had a little one long ago, like you. Snake oil?
It still makes a lot of sense to have drivers with very low resonance in moderate sized boxes. The argument is that air is more linear than mechanical suspensions. And sulfur hexafluouride more linear and with various other acoustic benefits. Why not?
Ben
The NHT-1259 had an fs around 18 Hz. Not quite as low as the AR1W/AR3 but in the ballpark. The idea worked, and still works (I used to have AR1W under JanZen electrostatics 50 years ago, still have an array of 1259).
Back in the day (of "music only") we were more than content with a f3 of 40 Hz. which both those drivers do in a sealed box. Put them in a properly tuned ported enclosure and you'll get an f3 in the teens, plenty low enough for today's HT (and 32' organ pipes).
But those floppy suspension drivers weren't designed for stupid-low bass in big boxes . . . back then there wasn't any need for it. There was no source material that demanded it, and no delivery system that could have provided it. The goal then was decent bass (to reproduce acoustic instruments) in small boxes to make "stereo" practical. And although the acoustics of low bass in small rooms was reasonably well understood the idea of 2 (or more) limited range "main" speakers with a monaural "subwoofer" was nascent at best . . . not really born until the advent of "Home Theater" and digital delivery systems in the early 80's.
OK... then are you saying it would make sense to have such a driver available today? As much as I have reservations about resonant-box designs, maybe something in the 13Hz range wouldn't be so bad. Or an AR-1 woofer in, say, a 3 cu ft sealed box?
True, it would need a floppy (compliant) suspension. Surely somebody could make a "mag-lev" suspension (assuming their energies would be better spent working on a concept like the Rice-Kellogg driver instead of a different concept altogether).
But excursion wouldn't need to be any more than any other driver of the same diameter for the same output.
BTW, has Vilchur's old contention that air makes a more linear spring than fabric spiders ever been settled? Or that the stuffing in the box does provide useful heat conversion?
Ben
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That sounds like trolling and if so would violate Rule #2.
Just who are accusing of what self-serving activity in your provocative post?
Ben
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I think so . . . but 10-20 cu ft boxes are never going to become popular or common in residential settings.
Once you get past box size there really is no downside. Comparing ported and sealed boxes (of the size and extension we're talking about) there really are no negatives for the ported . . . above 40-50 Hz (where the music is) there is no practical difference in SPL, cone excursion or group delay. Below that it's all about having any output at all (which the ported has and the sealed doesn't) . . . and neither "effects" nor organ pipes care one whit about the greater "delay" from the port.
Of course you can extend the low frequency response of sealed boxes (or IB) with equalization, but you quickly run into excursion limits . . . trading SPL for extension.
I share your reservations, though, about using ports for bass augmentation up in the range where most instruments play. There the tradeoffs are greater, and more likely to be audible . . . but you still do get more output from a smaller box . . .
Agree with your points about resonance in relation to music frequencies.
For same size box, boom design is louder lower. But what about AR-type drivers for the same size box?
The focus many have with sims removes people from thinking clearly about speaker qualities besides FR. Like distortion and transient behaviour - stuff really important to us ESL guys. Also, I spent many years working on motional feedback. For me, tight sound with no enduring resonances poking through matters a whole lot more than a few Hzs lower (although MF gives you both).
I know I shouldn't admit this publicly, but I have a theory that the textbook treatments of open-back baffle boards tend to greatly under-rate their bass output. The tones sneaking around from the back or an irregularly shaped enclosure aren't meeting the front tones in any orderly way and totally annihilating one another totally. Not in any real room.
Ben
For same size box, boom design is louder lower. But what about AR-type drivers for the same size box?
The focus many have with sims removes people from thinking clearly about speaker qualities besides FR. Like distortion and transient behaviour - stuff really important to us ESL guys. Also, I spent many years working on motional feedback. For me, tight sound with no enduring resonances poking through matters a whole lot more than a few Hzs lower (although MF gives you both).
I know I shouldn't admit this publicly, but I have a theory that the textbook treatments of open-back baffle boards tend to greatly under-rate their bass output. The tones sneaking around from the back or an irregularly shaped enclosure aren't meeting the front tones in any orderly way and totally annihilating one another totally. Not in any real room.
Ben
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"Distortion" does indeed have to be measured separately, but "transient behavior" (ie. "group delay") is shown by most if not all of the sims. "Boxing" my IB array gave a very noticeable improvement in lf "effects", but had no effect on perceived "transient response" of music . . . which is just what the sims predict. There is no change in group delay at 50 Hz. (where it is dominated by the crossover anyway), and negligible change at 40 Hz. Deep organ notes just sound . . . better . . .
Yes, but if anyone actually looked at group delay instead of trying to grab an extra dB or two at the south end, they'd all build sealed boxes! Or large open baffles. And after construction, be glad they did. I'd like to see evidence showing how close the sim is to the measured result.
Guess I am still living in the age of listening to clicks and watching the sound on scopes. Now that's still a good way to separate the boomers from the musical speakers.
Have to say my experience eyeballing square waves on a scope and trying to make REW group delay traces has not been fruitful.
On the other hand, nobody debates the fact that Quad 63 electrostatics stand at the head of the class (by far)* in producing good square waves... and good music.
Ben
*a Dayton-Wright ESL 8-cell panel does not make impressive square waves even if it does make impressive music. A DW stand-alone cell, however, will make pretty good square waves.
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But no bass to speak of . . .
and neither square waves (whether they matter or not) nor "transient response" is going to be effected in any audible way by adding the rumble of a subwoofer.
Agreed, again.
Now Dayton-Wright panels go down swell to about 40Hz. Not a bad design, I say.
But my (usual) conclusion is that making sound (even just bass) with Rice-Kellogg drivers is plain daft (cone drivers in horn possibly excepted). Like moving vehicles with internal combustion engines. It can be done... but not a satisfying engineering solution.
Ben
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