Was the 3 better than the 3a?

[Steve F]

Was the 3 better than the 3a?

An intriguing question. On “paper,” the 3a was an unquestionably improved design. The drivers with their greatly-improved dispersion, the lowered crossover points, AR’s published power response—all superb and they were all advancements over the 3. (Well, AR never published a system power response curve for the 3, so that is not directly comparable.)

Julian Hirsch said of the 3a in his April 1968 review, “The best frequency response we have ever measured using our present test set-up.” There was a published FR curve of the 3 in High Fidelity by Julian several years prior, but it wasn’t particularly uniform or flat, no doubt due to the measurement conditions and environment.

As to the 3-3a comparative sound quality, High Fidelity said “what was good has been made unquestionably better.” Julian said that depending on the position of the level controls, “either speaker could be made to sound better than the other,” although he implied that when the controls were set identically, the 3a was better.

But the disastrous 1968 Consumer Reports review of the 3a (where CU stripped off the Emperor’s Clothes and said exactly what AR’s harshest critics had been saying all along) really laid it out: that the 3a was thick-sounding, colored in the midrange and the tweeter (although it had a flat, extended response) was too low in level and could not be brought up to the same loudness as the woofer. CU said the 3a’s main problems seemed to be centered on the “new midrange driver.”

CU never reported those problems in an earlier test of the 3. Indeed, except for a general sense that the 3 may have been too “polite”-sounding, the 3 never received the very specific “thick” or “colored” criticism from anyone that the 3a often did.

So why did the 3a sound “thick”? Its 575 Hz w-to-m xover “should” have resulted in a faster, cleaner, more open-sounding midrange than the 3’s 1000 Hz w-to-m xover, right? And we all just know—without a doubt!—that the AR 12-inch woofer is far too ‘slow’ to take all the way up to 1000 Hz.

Roy Allison found a 2dB rise in the 3a’s woofer’s response when measured through the crossover at around 550-600 Hz, and that resulted in a new choke for the 3a a few years into its production life. That is probably the change that accounted for the 3a’s published crossover spec being changed from 575 to 525 Hz. Yes, 550-600 is directly in the “thick”-sounding region. Has anyone here done some extensive A-B listening to properly-functioning 1967 vs. 1971 3a’s? That would be interesting.

One thing we all know for sure, courtesy of 20-20 hindsight: the 3a’s thickness was not because of the “new midrange driver.” The AR-11 and 10π used the exact same driver and they didn’t sound thick. For that matter, all 1 ½” AR dome mids were essentially the same, so the 91-58s-78LS also used that driver, and none of those 12-inch 3-ways sounded “thick” either.

So what was it? It’s not that the 3a was a bad speaker—it was quite justifiably lauded as one of the best speakers ever made, with amazing dispersion and wide, smooth frequency response. Except for that trace of lower-mid thickness, it was as sweet and musical and unstrained as could be, plus with its phenomenal bass response—bass that has still never been equaled for deep extension, tightness and definition from a 1.48 cu.ft. enclosure. Never, not even close. So, yes, the 3a is a terrific speaker, one that I am proud to own and delighted to listen to.

But why does the 3a have that slight lower-mid heaviness that the 3 doesn’t? The $64,000 question.

 

Steve F.

[der]

Extremely interesting and informative post, Steve. Thank you. My 3a were built in 1969. I must have bought them in 69 and not 70 as I previously stated. I've recapped the crossovers and cleaned up the pots.  It would indeed be interesting to compare an early version to a later one using the new choke. Would it be possible to modify and earlier version with the later choke or would the entire crossover need to be rebuilt?

der

[samberger0357]

Great history lesson. Thanks. 

[Sonnar]

Steve , You know I'm a great AR 3's fan , and I have both AR 3 ( two pairs )and 3a, but I can' t say which one is better . To me AR 3 and 3a are the best speakers ever made , but depending on some program material one is better than other. I prefer AR 3 with chamber Music, baroque, jazz , while AR 3a are preferred with human voices, lyrical, symphonic , pop/rock . Surely AR 3's tweeters are more extended, sparkling and vivid than AR 3a ones, and the old Alnico woofer appears more linear . AR 3 midrange is " peremptory " and a bit " dry " as Julian Hirsch said, while AR 3a has a very powerful midrange . And the question is , this midrange is probably too powerful and tends to characterize the sound of the speaker? Best Regards, Adriano

[GD70]

I was lucky enough to have the opportunity to do an A/B comparison of the 3/3A a few years ago.

Roy had done work on the 3A's for this gentleman, and I refinished the cabs for him.

I did a very crude video with a point & shoot Cannon camera, trying to illustrate the sound differences between them, which you can basically hear.

The 3a's have ceramic magnet woofers, and Ohmite pots installed and were recapped. Roy also rebuilt his mids.

My 3's are early with oil caps, have original style pots in good condition from Roy and a few other sources, and one tweeter needed replacing. All other drivers sound great.

I had the pots set to max on both, trying to make everything as equal as possible I thought.

Listening back and forth, the 3A's were more forward in the mids and highs, bass not as deep as the 3's. The 3's were airier sounding, smoother, mids sounded slightly recessed, but not after listening to them for a while, bass was deeper.

Overall I prefer the 3's and the owner of the 3A's felt the same way.

Glenn

Here's the video link if you're interested. The 3A's have the grills removed. The 3's are at the far right & left.

 

 

[samberger0357]

Excellent Glen. Thanks. 

 

I've never heard a 3A, hope to one day. But I can wholeheartedly agree with your description of the 3's. Exactly as they sound to me. 

[frankmarsi]

This is so wrong!

"Those who forget history are condemned to relive it once again".

"Bring in the old elephants so that the new males will quiet down and stop their rampaging."

Is there another quote the elders on this site can use? Please!

This is sacrilege!  Poor "SteveF's informative and enlightening post has been besmirched.

fm

[Martin]

To add insult to injury, in their 1970 loudspeaker test report, CR said, to paraphrase from memory, that the 2aX was a better overall speaker than the 3a.  I still have that issue somewhere and will try to find it.  

[RoyC]

On 3/16/2016 at 8:20 AM, Steve F said:

But why does the 3a have that slight lower-mid heaviness that the 3 doesn’t? The $64,000 question.

 

 

Steve F.

I have had the opportunity to restore and compare very many of the old beasts, and have some thoughts on the matter.

-Regarding the early AR-3a vs the later AR-3a, I don't think the AR-3a inductor change for the 550-600 hz hump resulted in a significant sonic difference, primarily because the inductors were specific to different woofers. The new larger inductor (2.85 mh) came about when AR went to the ferrite magnet/foam surround woofer as a replacement for the original cloth alnico magnet/cloth surround woofer. Although the electrical characterisitics are very similar between the two versions, the cones, magnets, and resultant unfiltered sound are all quite different. The older woofer responds more cleanly well into the midrange. This is why it did so well in the AR-3, which allows it to run almost full range into the upper frequencies (only a .4mh inductor vs the AR-3a 1.88mh inductor). No "hump" was ever identified in the AR-3 even though the woofer was the same, and the inductor was much less restrictive.

I have never found the sonic difference between the early and later AR-3a to be dramatic unless someone had dropped a later woofer into an early cabinet. Replacing the older woofer with a later woofer in the 1.88mh inductor equipped early 3a cabinet (or, for that matter, in the .4mh inductor equipped AR-3 cabinet) does not work out well at all. The "hump" and undesirable midrange issues become quite apparent. In fact, I personally find the earlier version of the 3a to be very slightly less "stuffy" compared to the later version. At any rate, I don't believe the introduction of the ferrite/foam surround woofer, and associated larger inductor, actually changed the 3a's midrange response significantly.

-Regarding the AR-3 vs 3a, crossover changes and tweeter/mid versions had an effect on differences. Most iterations of the AR-3 crossover allow the mid to run full range to reinforce the tweeter's response (the 3a crossover does not do this), and as I mentioned above, the excellent earlier woofer is allowed to run much further into higher frequencies. In fact, with the exception of the very last AR-3's manufactured, the AR-3 mid is quite different from the AR-3a mid, both in construction and response. It is just a larger version of the tweeter, and the AR-3 tweeter and mid are allowed to run together with an extremely simple crossover. I agree, however, that the change in mids alone was not the cause of the 3a's  midrange response issue. I believe it was simply a design issue along, perhaps, with a weak AR-3a tweeter.

-Regarding the AR-3a vs the AR-11/10pi, when the AR-11/10pi came along, the 3a crossover and level control arrangement were tweaked to allow more mid output. It was also changed to accommodate a stronger tweeter.

Steve, in light of the above, and as in our conversation regarding the AR-5, the differences between the other models compared to the AR-3a may have much more to do with the influence of stronger/smoother higher frequency response on lower frequencies than anything else. I believe woofers that do well in midrange frequencies may play a part as well. I personally find the early AR-2ax (equipped with the AR-3 type tweeter and alnico magnet/cloth surround woofer), AR-5, and AR-3 preferable to either version of the 3a with regard to lower midrange response.

Roy

[Steve F]

What you are reporting gives credence to an earlier post of mine (I forget which topic or when it was) which spoke to the importance of spectral balance. The presence or absence of higher frequencies has a dramatic psychological influence on a listener's perception of overall "heaviness" or "brightness."

If the 3a suffered from a "weak tweeter" (certainly CU  felt that was the case) and the 3a's ferrite/foam woofer had an inferior midrange response to the Alnico 3 woofer, then that's a huge part of the explanation.

Here's another question: Did the 3's 1 3/8-inch phenolic tweeter have a higher on-axis level relative to the 3's woofer than did the 3a's 3/4-inch paper tweeter did to the 3a's woofer? We know that the 3a's tweeter had superior dispersion to the 3's tweeter, but that superiority was relative to the tweeter's own on-axis performance, and has nothing whatsoever to do with the overall level of the tweeter relative to the woofer within the system.

The 3's on-axis tweeter level relative to the 3's woofer vs. that question for the 3a is the critical question, in my view. There are no published system FR curves that will answer that, to my knowledge. AR published individual driver FR curves and a quasi-complete 3a system FR in the 3a "Technical Data" sheet. No corresponding "Data Sheet" exists for the 3, to my knowledge, so there doesn't appear to be any apples-to-apples comparison to make.

You have done much 3 and 3a restorative work and critical listening to both systems. What is your impression of the 3's tweeter level relative to the 3's woofer level, and how does it compare to the same question for the 3a?

Steve F.

[stan461]

I have owned both the 3 and 3a (Alnico woofer) for many years. Also, own the AR2ax (orange dome tweeter).

I keep one pair in the system for a month or 2 and then switch.

All 3 are exceptionally satisfying speakers. Much more similar than different.

That magic AR presentation (you are there) is what I am really fond of.

True, the AR2ax is lighter on the bass, but it's not night and day. And it's way better than I ever expected.

[RoyC]

8 hours ago, Steve F said:

What you are reporting gives credence to an earlier post of mine (I forget which topic or when it was) which spoke to the importance of spectral balance. The presence or absence of higher frequencies has a dramatic psychological influence on a listener's perception of overall "heaviness" or "brightness."

If the 3a suffered from a "weak tweeter" (certainly CU  felt that was the case) and the 3a's ferrite/foam woofer had an inferior midrange response to the Alnico 3 woofer, then that's a huge part of the explanation.

Here's another question: Did the 3's 1 3/8-inch phenolic tweeter have a higher on-axis level relative to the 3's woofer than did the 3a's 3/4-inch paper tweeter did to the 3a's woofer? We know that the 3a's tweeter had superior dispersion to the 3's tweeter, but that superiority was relative to the tweeter's own on-axis performance, and has nothing whatsoever to do with the overall level of the tweeter relative to the woofer within the system.

The 3's on-axis tweeter level relative to the 3's woofer vs. that question for the 3a is the critical question, in my view. There are no published system FR curves that will answer that, to my knowledge. AR published individual driver FR curves and a quasi-complete 3a system FR in the 3a "Technical Data" sheet. No corresponding "Data Sheet" exists for the 3, to my knowledge, so there doesn't appear to be any apples-to-apples comparison to make.

You have done much 3 and 3a restorative work and critical listening to both systems. What is your impression of the 3's tweeter level relative to the 3's woofer level, and how does it compare to the same question for the 3a?

Steve F.

Steve,

I agree with your comments about spectral balance being a significant factor in these comparisons, likely superseding the dispersion attributes of the AR-3a 3/4" dome tweeter.

I don't know what the difference was when the tweeters left the factory, but these days the larger AR-3 dome tweeter is consistently stronger than the 3a tweeter when compared in or out of their respective systems. As I mentioned above, the AR-3 mid also provides more high frequency support than the AR-3a mid....so in my experience the high frequency level of a properly functioning pair of AR-3's is greater relative to the woofer than that of the AR-3a. Although the AR-3a mid's output can be greatly increased with the level control, it does not enhance the highest frequencies in the same way as the AR-3 mid. Unfortunately, many AR-3 mids are now compromised by hardened material, which was originally applied to protect the voice coil gap. It is becoming increasingly difficult to make meaningful comparisons.

It is probably no coincidence that much of my work for Larry/Vintage AR these days is the repair of AR-3 mids and the replacement of AR-3a  tweeters.

Roy

[der]

Extremely interesting posts from Roy and Steve.  Thanks to you both. I'm wondering where an early pair of 3a like mine, with cloth surround woofers falls into the scheme of things?  I believe my woofers are the same used in the 3 with the new mids and tweets. My crossovers would be the early 3a version as well. The only 3a's I've ever heard have been early versions like mine.