AR3a Tweeters - Power Handling

[Zilch]

I'm moving some quotes over from Tom's AR Advertising thread for discussion here:

But, I do agree that AR did not understand rock and roll very well, and had an approach to tweeters that, while accurate and wide dispersion, was not at home with the larger amps of the era. Believe me, I know. I showed up in Norwood for free replacement tweeters so many times in 74 and 75 that the guys started giving me tours of the factory and introducing me to people. Then I would leave with 4 or 5 tweeters, which they hoped would last me a whole month this time.

Ken's speakers were LSTs with four AR3a tweeters each, presumably.

A few years later, after blowing tweeter after tweeter, I ultimately sold that pair of AR-3a's in favor of a pair of Large Advents. Little did I know at the time that I was severely underpowering the AR's, playing loud rock music, feeding those ill-fated tweeters a heavy diet of clipping distortion. The Advents were much more robust (and efficient) in that regard. But the Advents never pleased me the way the 3a's did. I thought that was the price I had to pay.

Of course, now I've come full circle. A pair of rebuilt AR-3a's now sits proudly in my living room, being "responsibly" powered. I still consider them the finest speaker I've ever heard, although I have a set of Allison Ones awaiting a rebuild.

With low-power amps, clipping blows them, and with high-power amps, cranking them does; loud rock music appears to be the culprit. Would it be fair to conclude that misapplication was/is the fundamental issue?

Though I haven't compared the curves, L100s had rolled-off highs, too, so it doesn't seem there was widespread desire to boost them with treble controls or EQ, and AR3a's could be "forward" voiced in the midrange with the level controls at Max, thus lacking only the boomy bass of West Coast rock sound. Is this possibly the primary reason they were/are overdriven?

[soundminded]

I'm moving some quotes over from Tom's AR Advertising thread for discussion here:

Ken's speakers were LSTs with four AR3a tweeters each, presumably.

With low-power amps, clipping blows them, and with high-power amps, cranking them does; loud rock music appears to be the culprit. Would it be fair to conclude that misapplication was/is the fundamental issue?

Though I haven't compared the curves, L100s had rolled-off highs, too, so it doesn't seem there was widespread desire to boost them with treble controls or EQ, and AR3a's could be "forward" voiced in the midrange with the level controls at Max, thus lacking only the boomy bass of West Coast rock sound. Is this possibly the primary reason they were/are overdriven?

You went so long without posting Zilch, I was thinking we should send someone over to check to see if you were still breathing.

"I showed up in Norwood for free replacement tweeters so many times in 74 and 75 that the guys started giving me tours of the factory and introducing me to people. Then I would leave with 4 or 5 tweeters, which they hoped would last me a whole month this time."

It wouldn't have mattered if they were 075s, they'd still have gotten burned out. It's interesting to observe how people with hearing loss often speak very loudly and of course they turn up the volume of anything they listen to often to the annoyance of people whose hearing is normally sensitive. Then for some of them, sometimes something interesting happens. They become extremely sensitive to any sound so that even music played at a normal level becomes irritating to them. This might suggest auditory nerve damage. One of the worst forms of hearing impairment must be tinnitis, like hearing a tone going off in your head all the time that never stops. Hearing impairment is no joke. It's especially sad when it is self induced as happens so often from abusive use of modern audio equipment.

This brings up an interesting topic for discussion, not one I'd guess you had in mind. Why do people want to listen to recordings at ear shattering loudness? What does that do for them? Is there something lacking in the quality or so little of whatever it is in recorded sound that people want to hear that it must be made up for in quantity?

[Steve F]

Like Gene K, I bought 2ax's in the early '70's ('72) and never blew a driver. My listening tastes were mostly jazz, but some of that was high volume (Mahavishnu Orchestra, Chick Corea's RTF, Weather Report, etc.). Nary a grown from the speakers, ever. Amplification was from two different Kenwood integrateds, 50 and 80 wpc.

(BTW, these speakers--woofs refoamed--are still going strong at a friend's house.)

My two older cousins had 3a's. No tweeter problems. One blown mid. (One of my cousins is a truly world-class jazz tenor sax player. I guess he wanted 'trane IN THE ROOM with him!)

Later I had LST-2's, never any problems, with a 125 wpc Mitsubishi pre-power combo.

That's my personal 3/4" non-ferrofluid tweeter history.

Steve F.

[Zilch]

It wouldn't have mattered if they were 075s, they'd still have gotten burned out.

The utility of 075s for railroad-car counting and wallpaper stripping is well documented.

It's interesting to observe how people with hearing loss often speak very loudly and of course they turn up the volume of anything they listen to often to the annoyance of people whose hearing is normally sensitive. Then for some of them, sometimes something interesting happens. They become extremely sensitive to any sound so that even music played at a normal level becomes irritating to them. This might suggest auditory nerve damage. One of the worst forms of hearing impairment must be tinnitis, like hearing a tone going off in your head all the time that never stops. Hearing impairment is no joke. It's especially sad when it is self induced as happens so often from abusive use of modern audio equipment.

I did not perceive Ken as being particularly "hearing impaired" when I met him recently.

This brings up an interesting topic for discussion, not one I'd guess you had in mind. Why do people want to listen to recordings at ear shattering loudness? What does that do for them? Is there something lacking in the quality or so little of whatever it is in recorded sound that people want to hear that it must be made up for in quantity?

The same reason that only forte and crescendo can bring a concert hall to life.

Take your trusty R/S SPL meter with you next time you go.

Alas, you'll never know the transcendent pleasure of riding a flying pig to the dark side of the moon....

[RoyC]

The AR-3a used a single (6uf) cap for the tweeter crossover. A simple 6db/octave crossover does not afford much protection, so that probably did not help matters.

Roy

[genek]

The AR-3a used a single (6uf) cap for the tweeter crossover. A simple 6db/octave crossover does not afford much protection, so that probably did not help matters.

I don't think my 2ax's tweeter crossovers provide any more protection than the 3a's?

[RoyC]

I don't think my 2ax's tweeter crossovers provide any more protection than the 3a's?

Probably not...but the very low impedance 3a is easier to clip an amp with.

Roy

[soundminded]

But a musical crescendo lasting for several seconds is in no ways comparable to the continuous output we find with rock music. Even a lot of action movies pale in terms of wallop, compared to a lot of heavy-metal stuff. The speakers get to cool down during intervals, whereas rock music often keeps pounding (and heating) the drivers continuously for minutes (often many minutes) at a time.

Most baroque and classical music (and even a lot of the romantic-era stuff) is not all that loud sounding, even at live performances. The orchestra may heat up during a romantic-era finale, but that energy outlay does not compare to what some enthusiasts care to simulate with rock-concert levels in their listening rooms. I imagine that a lot of rock lovers are having hearing problems at a fairly young age.

PS: and trust me, a good piece by Telemann, Vivaldi, or Handel can bring a concert hall "to life" without ratting the rafters.

Howard Ferstler

Rock music(?) has extremely limited dynamic range. I read in one audio text (can't remember where) that for many reasons rock rarely exceeds 10 db in dynamic range. This makes dynamic compression including Dolby and peak limiting unnecessary. How lucky for rock musicians, almost any of their ditties can be trasnposed into the key of C Major if it wasn't written in that key to begin with. No sharps or flat to worry about.

Zilch, it may come as a surprise to you that for many people...well for a dwindling few of us anyway, it is the beauty of sound that is the primary reason they like music. When music has great dynamic range, the loud parts have far greater impact due to their contrast with the rest of the music than for music where the sound drones on and on at the same unmodulated loud level all the time. The good news is that rock compositions rarely last more than 3 or 4 minutes each. The worst singer born, amplified through a mighty JBL sound system can produce sound far louder than one of the greatest tenors of all time like Luciano Pavarotti can on his lung power alone (his story was on PBS last night.) But what worlds apart in quality. Like a big ugly bolder compared to a brilliantly cut and faceted diamond.

Zilch, through the miracle of microminiaturization of electronics, an in-the-ear hearing aid is virtually undetectable. You could be talking to someone up close and neither of you would know the other is wearing a pair

[Zilch]

Let's pretend there's no power compression in the concert hall. That's its very purpose -- to adulterate the music and render it mush to the listener.

You'd do well to try and play some "ditties." Begin with something benign, like the Beatles. Don't be trying to bend any of their notes, though. Put a whammy bar on the ol' Steinway, maybe.

Zappa or Santana? Don't even try.

It's a given: all loudspeaker designers are deaf; that's why they measure....

[kkantor]

I'm moving some quotes over from Tom's AR Advertising thread for discussion here:

Ken's speakers were LSTs with four AR3a tweeters each, presumably.

With low-power amps, clipping blows them, and with high-power amps, cranking them does; loud rock music appears to be the culprit. Would it be fair to conclude that misapplication was/is the fundamental issue?

Though I haven't compared the curves, L100s had rolled-off highs, too, so it doesn't seem there was widespread desire to boost them with treble controls or EQ, and AR3a's could be "forward" voiced in the midrange with the level controls at Max, thus lacking only the boomy bass of West Coast rock sound. Is this possibly the primary reason they were/are overdriven?

Some comments:

1- I sometimes played the speakers very loud, like out the window of a dorm loud. Probably, if replacement drivers hadn't been so free flowing, other people's speakers would have been used for the parties....

Actually, a floor-mate and good friend had Olympus's that could seriously rock, but which didn't fit in the window.

2- If the amp is big enough and the speakers are clean, blown drivers will pretty much always occur eventually. During serious listening, where no conversation is happening, there are no cues to "turn it down" other than pain or distortion. If the threshold of pain is not reached, and distortion is not heard, the level will tend to rise until the speakers die.

3- I don't believe any speaker has ever been blown by the "harmonics caused by clipping." This is a convenient myth that was perpetuated by AR, JBL and amp companies. If you do the math, or measure the signals, the harmonic series just doesn't carry enough energy to matter. It's all about RMS heating.

http://www.audiovisualdevices.com.au/downl...ane/note128.pdf

-k

[Pete B]

I'm moving some quotes over from Tom's AR Advertising thread for discussion here:

Ken's speakers were LSTs with four AR3a tweeters each, presumably.

With low-power amps, clipping blows them, and with high-power amps, cranking them does; loud rock music appears to be the culprit. Would it be fair to conclude that misapplication was/is the fundamental issue?

Though I haven't compared the curves, L100s had rolled-off highs, too, so it doesn't seem there was widespread desire to boost them with treble controls or EQ, and AR3a's could be "forward" voiced in the midrange with the level controls at Max, thus lacking only the boomy bass of West Coast rock sound. Is this possibly the primary reason they were/are overdriven?

I'd guess that you probably already know this but there are two main failure modes

for loudspeaker drivers, themal, and mechanical. Thermal is obvious, too much power

leads to too much heat that cooks the voice coil. I've seen the enamel coating charred

to black with the windings completely shorted. Anything to sink heat away helps, a thermally

conductive former such as aluminum (most common today), rather than paper, and

ferrofluid obviously. Mechanical failure in tweeters is most often breakage failure of

solid lead in wires, tinsel wires are the obvious solution.

Woofers can have glue joints fail, and more often have basic stress fatigue when driven

hard.

I have a few failed, black paper dome AR-3a tweeters here; they have paper formers

and solid lead in wires.

Another consideration is efficiency; obviously for equal SPL level a higher efficiency tweeter

will require less power and will therefore see less thermal stress.

The EPI 100 and even the Large Advent (full production) tweeters both had aluminum formers

and tinsel lead in wires.