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AR-3A speakers, Why were they so good regarding the deep Bass

markbark12

markbark12

New Member
GOOD GOD IT'S BASS Hi everyone! Been away about ten years. Glad to be back! I have just rebuilt a pair of AR-3A speakers. I love the way they sound but after the rebuild I'm left with some questions and a few comments. Firstly why was such a thin grade of copper wire used for the outside mid and tweeter connections...in fact why the external connections at all? Why wasn't more fiberglass used to fill the boxes rather then the rather loose filling used? the bracing could have been more substantial. It seems to me that for a speaker that cost a fortune back in the day better caps and resistors were not used, even the pots seem somewhat cheap. I wonder even how such great deep base is developed. Yes, the free air resonance of the woofer is a very good 18Hz but the cones are not very heavy or have added mass and they certainly are not what we would consider " long throw " today. I'm not an a speaker designer or have a degree in physics but what am I missing here? Someone please "educate me". Have a great day! Mark
 
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Please define " proper design" knowing that I understand " cost vs performance". Good god, it's bass Moderator please HELP!!!
 
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Are you aware that this is the evolution of the woofer from the inventor of the first
mass produced HiFi acoustic suspension (AS) systems?
http://www.classicspeakerpages.net/...nal_ar_documents/commercial_acoustic_suspens/

https://www.google.com/patents/US2775309

http://www.aes.org/historical/store/oralhistory/?code=OHP-059-DVD

My thread on the subject, note
that many on the internet claim that Villchur invented AS and I believed them at the
time of my first post, then decided to look it up and clearly Olson was the inventor but
didn't really promote it. Details here:
http://techtalk.parts-express.com/f...5-ed-villchur-s-acoustic-suspension-invention
 
Thanks all, Pete, is that the same Olson who established Olson electronics? ( long long gone lol). Yep I'm dating myself big time. I have a copy of 1966 catalog.
The links are great!!!! Oh and Skipper, Did you ever meet the Harlem Globe Trotters ROFL! As for your post thanks but still scratching my head. On line freq generators take the AR-3A down to a clean 24HZ....amazing. Now the bad part, can only hear up to 9,000 hertz. ( I'm 72 lol) Not including sub woofers (many can't reach that low) which speakers have you heard with better clean bass...Carver Amazings, Ohm F? Haven't audition any new speakers for ten years LOL and Stereophile bored me to tears! I think I have over 1000 catalogs and mags BTW
 
Good god...Sorry I am getting senile. been spelling BASS...base sorry. Anyway I can change my heading......walking away in shame lol...moderator PLEASE HELP!!!!!
 
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The early acoustic suspension speakers really were "cut-and-try" to a great extent. We know today that the Thiele-Small parameters for a driver (which include free-air resonance, cone mass, Q, etc.) allow us to choose various box "alignments" from sealed to ported, and get desired characteristics out of the entire system. Ed Villchur surely spent a lot of time manually optimizing cabinet size, damping materials and crossover networks to get to the same point, which was the only method available at the time. Of course, he was limited by things like the Xmax and electrical hardware of the speaker, which is why today's woofers can go even lower and with less distortion at higher levels. But he got something which was very effective for the time and certainly changed the way many manufacturers thought about speakers. Vented systems didn't really make a resurgence until the early 70s when we began to apply our knowledge of speaker parameters to calculate box designs. People like Ray Newman and Don Keele at Electro-Voice were pioneers here - I corresponded with them while working on my senior project at college to get a sense of the current thinking in low frequency speakers. They built a speaker called the Interface:A which was half the size of an AR-3A and was flat to 32 Hz, yet more efficient. It was more of a proof-of-concept that anything else, but their work led to better vented systems just as Villchur's designs made the acoustic suspension concept a common denominator of speaker design in his day.
 
Electrovoice built and marketed the Interface A around 1975 -76. And a smaller version called the Interface B. My friend had a pair and I saw them advertised in Stereo Review.
 
GregDunn said:
The early acoustic suspension speakers really were "cut-and-try" to a great extent.
Click to expand...

AS is so simple that it was hardly cut and try, they knew that Fc set the point where the 2nd order
roll off happened and to adjust cone mass to get what they wanted. They chose Fc in the low 40s
so that the system would reach to low E on a 4 string bass. Villchur specified a high source
impedance in his late 1950s AES paper so that the effective Qtc would be close to one, where
they knew that the response would cross zero dB at Fc with (very) slight peaking above.
I'd say that they knew exactly what they wanted and were getting.
 
By exactly what they wanted, you are touching on something that seems to have gotten lost in the intervening time. Even as using Thiele Small parameters, computer modeling, and a variety of sensors that didn't exist back then have allowed great strides in speaker design, fewer and fewer designers seem to have a clear sense of what speakers are actually supposed to sound like, as opposed to how well they measure by some specific measurement technique.
Vilchur, Bozak, Briggs, Fisher, Lowther, Brociner, and many of the designers of the early HiFi era were music lovers, and their involvement in audio was in service of that love. They used their knowledge of how actual instruments and orchestras sound like to design speakers to take advantage of their actual range and dynamics, rather than a theoretical flat 20 to 20kHz.
Nowadays, designers may love music, but our culture's idea of music is primarily reproduced music, and usually amplified music to begin with, rather than acoustic instruments. The idea of a natural sound is not really a central focus.
 
Basically, it was a true "Acoustic Suspension" design. The vast majority of sealed boxes aren't. The AR 3A woofer was designed with a very low resonance; so low that in a vented box it would not make any bass. It needed the sealed enclosure to provided the suspension or "spring" if you will that allowed the woofer to function. If you take almost any woofer out of a sealed box today and put it in a vented box or mount it on a big board (or in a wall) to get an approximation of a infinite baffle (keeping the rear wave from canceling the front) it will work. The AR 3A woofer won't. Almost all sealed enclosures today are actually a type of infinite baffle, not an acoustic suspension enclosure.
 
Interesting point, and, I think, correct. A lot of 'acoustic suspension' designs are actually just sealed boxes. These small infinite baffles may sound very nice, but they cannot produce deep bass - though they can produce a bass bump that may confuse us into thinking they have low bass. Not that any of us are such suckers that we can be fooled in such an obvious way...
 
markbark12 said:
GOOD GOD IT'S BASS Hi everyone! Been away about ten years. Glad to be back! I have just rebuilt a pair of AR-3A speakers. I love the way they sound but after the rebuild I'm left with some questions and a few comments. Firstly why was such a thin grade of copper wire used for the outside mid and tweeter connections...in fact why the external connections at all? Why wasn't more fiberglass used to fill the boxes rather then the rather loose filling used? the bracing could have been more substantial. It seems to me that for a speaker that cost a fortune back in the day better caps and resistors were not used, even the pots seem somewhat cheap. I wonder even how such great deep base is developed. Yes, the free air resonance of the woofer is a very good 18Hz but the cones are not very heavy or have added mass and they certainly are not what we would consider " long throw " today. I'm not an a speaker designer or have a degree in physics but what am I missing here? Someone please "educate me". Have a great day! Mark
Click to expand...
All this massive amounts of base could just be proper placement, just the right room acoustics for the speakers in question and the right amount of power.
 
markbark12 said:
GOOD GOD IT'S BASS Hi everyone! Been away about ten years. Glad to be back! I have just rebuilt a pair of AR-3A speakers. I love the way they sound but after the rebuild I'm left with some questions and a few comments. Firstly why was such a thin grade of copper wire used for the outside mid and tweeter connections...in fact why the external connections at all? Why wasn't more fiberglass used to fill the boxes rather then the rather loose filling used? the bracing could have been more substantial. It seems to me that for a speaker that cost a fortune back in the day better caps and resistors were not used, even the pots seem somewhat cheap. I wonder even how such great deep base is developed. Yes, the free air resonance of the woofer is a very good 18Hz but the cones are not very heavy or have added mass and they certainly are not what we would consider " long throw " today. I'm not an a speaker designer or have a degree in physics but what am I missing here? Someone please "educate me". Have a great day! Mark
Click to expand...


The speaker was designed in the 1950s and was a design achievement 70 years ago. It's not the best sounding speaker, in my opinion, but it's a timeless design.
 
Increasing or decreasing the woofer cone throw would cause distortion because the "spring" characteristics would be compromised.
 
Not sure I follow you. I believe one of Vilchur's points about acoustic suspension is that the compression and rarefaction of air is vastly more linear than any mechanical suspension, so the response to increased signal would (up to the point of complete failure) be a predictable and relatively linear increase in resistance to motion.
If what you mean is taking a driver of a specific compliance and sticking it in a unsuitable sized box would cause distortion, then I agree.
 
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