10" woofer interchange

[charger3834]

If the AR-5 Woofer is inherently different in design than that of the new AR-2ax, to what degree are they interchangeable for restoration purposes. Can an AR-2ax serve as a woofer doner to an AR-5 since it only needs to rise to 650 HZ or 550 HZ ? Why was the AR-5's crossover frequency lowered in the 70's anyway ?

I have seen several AR-5's on ebay with a woofer that looks identical to the AR-2ax (Flat Dustcap). Are these newer versions or retrofits ?

[tysontom]

>If the AR-5 Woofer is inherently different in design than

>that of the new AR-2ax, to what degree are they

>interchangeable for restoration purposes. Can an AR-2ax serve

>as a woofer doner to an AR-5 since it only needs to rise to

>650 HZ or 550 HZ ? Why was the AR-5's crossover frequency

>lowered in the 70's anyway ?

The original AR-5 woofer was different, but only marginally so. Nevertheless, this original-style AR-5 woofer was not as well suited for the AR-2ax's higher crossover, so it would probably be a little rough, and possibly down, in response in the 1KHz region needed in the AR-2ax. Conversely, the AR-2ax-style 10-inch woofer works satisfactorily in the AR-5 with some minor performance trade-offs. Incidentally, the AR-8 woofer was yet again different -- it had a shorter voice coil with less "overhang" for increased efficiency. It also had added mass in the cone, I believe, to slightly lower resonance. It was significantly underdamped if I remember, and this gave it a more "thumpy" bass characteristic than most of the other designs. I personally don't think it was AR's finest hour.

As I mentioned earlier, AR had by 1985 or so begun to standardized the 10-inch replacement woofer as "one-size-fits-all," and it was basically the AR-2ax woofer design with the new ceramic-ferrite magnet.

>

>I have seen several AR-5's on ebay with a woofer that looks

>identical to the AR-2ax (Flat Dustcap). Are these newer

>versions or retrofits ?

This would be the newer-style woofer, basically the AR-2ax design.

--Tom Tyson

[charger3834]

Thanks Tom, that about covers that. Happy Thanksgiving !

[tysontom]

Why was the AR-5's crossover frequency

lowered in the 70's anyway ?

I rambled on about the AR-5 and AR-2ax woofer, but I did not say anything about reason behind the lower crossover. Rememeber: AR's engineering direction during the 60s was ever-wider dispersion and power response. Since the new AR-5 dome midrange could go lower with better dispersion and power-handling than the AR-2ax's midrange 3-1/2-inch driver, that is what was done in the AR-5 (as in the AR-3a). This also kept the woofer in the AR-5 from having to cross over at a frequency where it was beginning to get directional and a little rough in response. The end result is a speaker with superior performance over the AR-2ax in the midrange with respect to dispersion. Another factor was the cost of crossover components, and the larger caps were more expensive in the AR-5, which had a higher price point. In other words, the AR-2ax might also have had a lower crossover frequency, but the crossover components were significantly more expensive and I don't think warranted the added cost.

Ironically, some people preferred the sound of the AR-2ax over the AR-5 probably due to the somewhat more directional characteristics of the 3-1/2-inch cone midrange. The measured performance of the AR-5, however, was significantly better than the AR-2ax.

--Tom Tyson

[tysontom]

>Why was the AR-5's crossover frequency

>lowered in the 70's anyway ?

>

>I rambled on about the AR-5 and AR-2ax woofer, but I did not

>say anything about reason behind the lower crossover.

>Rememeber: AR's engineering direction during the 60s was

>ever-wider dispersion and power response. Since the new AR-5

>dome midrange could go lower with better dispersion and

>power-handling than the AR-2ax's midrange 3-1/2-inch driver,

>that is what was done in the AR-5 (as in the AR-3a). This

>also kept the woofer in the AR-5 from having to cross over at

>a frequency where it was beginning to get directional and a

>little rough in response. The end result is a speaker with

>superior performance over the AR-2ax in the midrange with

>respect to dispersion. Another factor was the cost of

>crossover components, and the larger caps were more expensive

>in the AR-5, which had a higher price point. In other words,

>the AR-2ax might also have had a lower crossover frequency,

>but the crossover components were significantly more expensive

>and I don't think warranted the added cost.

>

>Ironically, some people preferred the sound of the AR-2ax over

>the AR-5 probably due to the somewhat more directional

>characteristics of the 3-1/2-inch cone midrange. The measured

>performance of the AR-5, however, was significantly better

>than the AR-2ax.

>

>--Tom Tyson

It has just occurred to me that I really didn't answer the question, but went off on a tangent about the difference between the AR-2ax and the AR-5 crossover. This is somehow what I read into the question. I am pretty sure that the AR-5 always had a 650Hz crossover, and not the 550Hz as was printed in a subsequent AR brochure. The 550Hz was a misprint, I think, unless a change was made when AR discontinued paper-dialectric capacitors and went to electrolytic caps in the early 1970s. The same thing is true of the AR-3a 575 vs. 525Hz crossover; I think it was always 575Hz. The AR-10Pi and AR-11 did, however, have the 525Hz crossover.

--Tom Tyson

[Steve F]

"It has just occurred to me that I really didn't answer the question, but went off on a tangent about the difference between the AR-2ax and the AR-5 crossover. This is somehow what I read into the question. I am pretty sure that the AR-5 always had a 650Hz crossover, and not the 550Hz as was printed in a subsequent AR brochure. The 550Hz was a misprint, I think, unless a change was made when AR discontinued paper-dialectric capacitors and went to electrolytic caps in the early 1970s. The same thing is true of the AR-3a 575 vs. 525Hz crossover; I think it was always 575Hz. The AR-10Pi and AR-11 did, however, have the 525Hz crossover.

--Tom Tyson"

The AR-5 and 3a crossover changes from 650 to 550Hz and 575 to 525Hz respectively were not misprints. I too had noticed these specification changes in their 1974 literature, so I wrote to them asking what the reason was for the change.

I received a letter back from AR saying that the current literature simply reflected "...changes that were made some time ago." No other details were given. I can probably dig out the letter and see who wrote it, but the point is, they acknowledged that the crossover change was real.

Steve F.

P.S. Mark-- I have a lot of correspondence from AR in the early '70's. Although I no longer have my original letters to them, I have AR's letters back to me, and one can glean the questions I asked from AR's answers. Their letters are pretty short and not always as detailed as I would have liked, but some 30-odd years later, people may get a kick out of reading them. I'll send them for you to scan if you'd like.

[administrator]

Hi Steve,

Sounds good! I have moved since your last round of submissions, so send me a quick email and I'll get you updated shipping information.

Thanks!

Mark

[charger3834]

>"It has just occurred to me that I really didn't answer the

>question, but went off on a tangent about the difference

>between the AR-2ax and the AR-5 crossover. >

>--Tom Tyson"

Tom,

Some of the most interesting stuff comes out of your frequent digressions. Keep it up !

>

>

>

>The AR-5 and 3a crossover changes from 650 to 550Hz and 575 to

>525Hz respectively were not misprints. I too had noticed

>these specification changes in their 1974 literature, so I

>wrote to them asking what the reason was for the change.

>

>I received a letter back from AR saying that the current

>literature simply reflected "...changes that were made some

>time ago." No other details were given. I can probably dig out

>the letter and see who wrote it, but the point is, they

>acknowledged that the crossover change was real.

>

>Steve F.

>

Steve,

I wonder if AR wondered why you had to know that. AR must have recieved a lot of letters since they were such an end-user focased company. If I would have had the opportunity to be an original AR owner, I would have asked a lot of questions like that too !