Aadams

There is a fairly recent thread that discusses this. The quick version is the statement above is correct. IIRC, the 91/92 mid has less ferro fluid in order to enable its use at the lower crossover of 700hz. The 90/9 mid has more ferro fluid in the expectation of higher acoustic output but still suitable for a 1200hz crossover point..............used in a 91 or 92 it would not comfortably extend to 700hz.

See the Tom Tyson post in this thread. He says it should have it if 1961 or later.

Here is more info from 2003. This is pasted from the attached thread above: The AR-3: I love this speaker. I think it is the highest single technical achievement from Acoustic Research in terms of innovation and "contribution." Its accuracy and low distortion were state-of-the-art, and clearly the AR-3 was the best loudspeaker commercially available throughout the late-50s and on into the mid-1960s. It literally changed the way the industry thought about loudspeakers, and it is still considered a fine loudspeaker after almost forty-five years. Despite its classic status, the AR-3 was certainly not perfect, and part of that imperfection came from the technical limitations and compromises that existed back in the late 1950s (and to a lesser degree today). The woofer in the AR-3 was crossed over at approximately 1000 Hz., but it was starting to get ragged off-axis by 800 Hz. or so. On axis, AR measured the low-frequency capability of the AR-3 at +/- 1.5 dB, 38-1000Hz, and 6-dB down at 30 Hz. Because of the woofer’s prodigious low-bass output, there is significant, if reduced, output down to 20 Hz. and below. The woofer gets quite "directional" at that upper frequency (in contrast, the AR-3a's 575-Hz. crossover was better, and its 1-1/2-inch midrange driver could go lower than the 2-inch AR-3 unit, and it had greater excursion capability). Nevertheless, the crossover slopes are gentle in the AR-3, so the 2-inch midrange -- with its excellent off-axis response -- is working pretty well at 1000 Hz., and overlapping the woofer's response somewhat. The 2-inch midrange driver in the AR-3 is crossed over at 7,500 to the tweeter, but could have been operated from 1000 Hz. to 15,000 Hz. or so, if the AR-3 had been a 2-way design. The 1-3/8-inch "super tweeter," as it was known, was AR's most perfect driver at the time. It had a gently rising characteristic up through 7,000 Hz. and on out to 20,000 Hz. The 7,500 Hz. crossover was an optimum point for this tweeter. The high-frequency section of the AR-3 had a measured (anechoic) response of 1000-20,000 Hz., +/- 2dB, on axis. Measured 45-degrees off-axis, any direction, the response was -3dB at 10,000 Hz., and -8dB at 15,000 Hz. This is pretty good performance by any known standard. Incidentally, this was not a “system” response, per se, but the individual-driver measured response, measured in AR's and MIT's anechoic chambers. AR published all these curves and made these available to anyone upon request, another unique AR trait. --Tom Tyson

The cabinets are definitely AR or incredible copies and the drivers that you show are AR3. I would want to see the drivers in the other cab before I purchased the pair.

Did you replace with Pots or lpads? Same result in both speakers? Post photos of the crossovers as they are now.

That is not the tweeter for an AR11 but it will fit. The tweeter discussed in the attached thread will work as drop in replacement for an AR11

Yes it will fit but I can't recall ever seeing a version of that tweeter body with the style of dome you are showing. Look at the back side for more info it could be a service replacement version. Others may know more. What problem are you trying to solve? If you have dead tweeters in your possession they can be rebuilt.

I thought I remembered reading about this topic in an old thread. I found it in an @tysontom post about 3/4 of the way down. Here is part of the post “I really don't have a preference. I have such great respect for both speakers that I enjoy listening to either system. Clearly, the AR-3a was a improvement over the AR-3 in several respects, such as off-axis response and power-handling. The AR-3, however, received higher critical acclaim when it was introduced, and it set the standard of performance, but it came out (technically) nine years prior to the AR-3a. It has become a great classic in every since of the word. The AR-3a certainly improved upon the same formula that made the AR-3 such a good speaker, but the refinements were quite subtle. For example, there are no pronounced differences in the measured response of the two speakers -- there are more similarities than differences. I heard a "new" AR-3 and a "new" AR-3a compared in the AR Music Room in 1967, and the "new" speakers sounded much more alike than have been described by some people on these pages.”

I think @Chris1this1 made those.

Those look like the very early, very rare and desirable long throw woofer version. See the link above. You will need advice from an expert on the spider repair assuming they are repairable. There is no replacement equivalent for the long throw woofer.

Have you considered wiring the filter externally?

It sounds like you know what you are looking for so I'll cave and say it may be your amp which I believe is 1970s vintage. I personally would be leary operating 3as with any old unrefurbished amp considering there are reliable new ones with warranties at reasonable prices. The headphone comparison works for more than just the bass. Decent headphones can give you a good reference for setting the frequency balance of the speakers in the room.

The 3a is strong at 40hz. The vast majority of recordings have nothing lower than 42hz and it looks like your amp can supply around 100 wpc which is plenty in most home listening spaces. If you have a pair of decent over ear headphones compare the 3a to the headphones. Good flat bass is just there, not prominent unless it is the featured part.

Deep bass from an AR3a is mainly a function of placement with respect to room boundaries. If you have adequate power now, for your room size and listening position, then more power won't provide deeper bass.

Ligs Others have pondered this solution. The LST is a special animal, sui generis. All of the LST drivers have predetermined output settings and the mids remain at an invariable matched output. Additionally the baffle is shaped to maintain flat power response to 32hz when it is placed against the wall. Doing this with multiple AR3as would require in wall mounting or an equivalent which would not allow for angling the mids and tweeters, and you still must figure out how to sync the output of all the drivers while having zero control of the bass driver. Not saying it can't be done but it would not be as simple as connecting multiple identical ARs to the same signal source. Aadams

Reconing these old speakers is risky. In the wrong hands the speaker will change character. Correct surrounds are low risk and do not change the character. If you have new surrounds then you could hear rubbing because the voice coil was not centered when installed. It is also possible the voice coils were damaged before new surrounds were applied. Of course, if you had to remove staples to see the woofer it is unlikely these have ever been repaired and what appears as intact surround is actually quite weak and about to disintegrate. Are you inclined to do your on work? If so download and review the AR3a restoration guide. Much of it applies to the AR2ax. Photos of front and rear of each cab with grills off will be helpful.

You might want to slow down and post some pictures of your speakers with grills off. Are you aware that you yourself can easily repair woofers in most cases?

What is the crossover freq of the Revel to the Infinity?

What year manufacture? Have you owned this pair from new? If so is the first time they have ever been opened? Does the problem move when you swap the left/right channel speaker wires either at the amp or the speakers? Photos, grills off, of the speaker fronts and backs could be helpful. Adams

Did you build the cabs? I can see an 8” 3 way or is this a 4 way or perhaps 5 way with a subwoofer?

Is this the same as an Infinity Kappa Perfect 6.1?

Are you talking about two different projects? MTM VS MTTM. Are the Revels blended with the infinity’s or running wide open? What happened to the big subwoofers?

What ar_pro said. If you will be listening to 1960s recordings then 1960s vintage electronics should be adequate. If you will playing modern recordings, more power is better. Regarding ported systems vs AR2ax power requirements: The 2ax is more sensitive than most modern 8 ohm ported designs but a good bit less sensitive than some old, quite large, ported systems of its day.

Look at page15 in the 3a restoration guide. As long as they are in parallel they can be mounted anywhere from on the lpad to on the driver. Most are placed on the lpad. If you are not having your tweeters rebuilt or using the Hivi mod then don't put the resistor on the tweeter lpad. The lpad alone will boost the output of your old and very tired tweeters if they are still working. There is no way your tweeters are in good health even if they seem to work. Adams

Top is an 8 ohm lpad. Do you have the 10 watt 25 ohm resistors to make them mimic the original pots?