AR 3a Improved

[Richard Grayson]

Hello everyone,

I am a new member from Australia and am extremely excited to find this site.

I have owned a pair of AR 3a improved since new (bought about 1978) and they are still performing beautifully though I have not tested the electrics.

I can find minimal information regarding specifics about the drivers and electrics ( crossovers etc)

The Ar 3a improved seem to have been built in a narrow window between the late AR 3a's and the early AR11's. The speaker cabinet cosmetics are obviously different but can anyone tell me the specific differences or commonalities compared to the late AR 3a's and the early 11's. Any information regarding drivers, crossovers, pots etc would be greatly appreciated.

Have a Merry Christmas and a good New Year

Regards

Richard

[JKent]

Welcome Richard

We have other members in Oz, so you're not the only one!

A couple of members have the AR3a Improved speakers. I believe John O'Hanlon has a pair and perhaps he'll comment.

There is some discussion of them here: http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=895

here http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=5800

crossover here http://www.classicspeakerpages.net/IP.Board/uploads/monthly_03_2008/post-100900-1204644282.jpg

here (especially johnio’s post) http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=4396

and here http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=1636

also download the AR-3a restoration manual. There are parts that are relevant to the Improved: http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/

Kent

[Richard Grayson]

Hi Kent,

Thank you for these leads. I have read them all, together with "Restoring the AR 3A" and have gained a wealth of knowledge. Thank you to all those who contributed to the threads.

I tested my speakers as per "Restoring the AR 3A" and found that all drivers were performing properly, as expected. The A-B switching on the back panel was working with a slight but audible difference in sound. All good!

My only concern now is that after my reading about capacitors, inductors and resistors, I do not know if the speakers are performing at optimum. They still sound beautiful but I have no reference to compare their current performance as to original performance.

Is it worthwhile to remove the woofer and test all the electrics? I am not an electrician and have no skills in soldering etc.

The history of the speakers is as follows:

I have owned the speakers since new, Bought in about 1978. The 12" drivers were professionally re-foamed in the late 80's. The hi-range drivers were replaced (By AR) in the early 90's after they were fried during one of my daughter's unauthorised parties. After the Hi range drivers were replaced, AR tested the speakers in a "Aneroid? chamber" and advised that they were performing "faultlessly".

The Hi Range driver is an "A23"

The mid range should be an "A14" but is the centre is coloured the same as an "A15".

The 12" driver is either an "A4" or "A5".

I have tried to upload some photos but each file is too large and I don't know how to make them smaller,

Any advice would be greatly appreciated as I feel I am a custodian of something special.

Regards

Richard

PS: 1948 was a classic year!

[RoyC]

Hello Richard,

The AR-3a Improved is essentially an AR-3a with switches (instead of pots), as well as a somewhat different crossover. I believe the Improved was only produced wih the Europen style cabinet.

If they still sound satisfactory to you, there is no need to tear into them right away. I would wait untl the woofers require re-foaming again, or until something doesn't sound right. You are the original owner and have listened to them for a long time, so you will probably know if/when something is amiss. When the time comes, replacement of all crossover capacitors would be the prudent thing to do.

Roy

[Steve F]

It was somewhat interesting and frustrating--both--to see this discussion go round and round as to whether the 3a/Improved had a FF-cooled tweeter or not.

I did not. It was an AR-3a with a slightly modified crossover and a 2-pos switch instead of pots. The x-o change was to remove "a small amount of coloration in the midrange" but AR never specified any further detail that I am aware of.

In the Library under "Letters to Steve F," AR told me quite explicitly in 1974 that the 3a/Improved was a European version of the 3a but was not going to be marketed in the US.

I posted a Dutch ad for the 3a/Improved with its English translation about a year ago. All the 3a/Improved info has been here on the site all along.

Here is that translation again:

The AR-3A/Improved

The evolution of a new loudspeaker

Since 1959 the ‘3’ series of Acoustic Research has been the leader in the reproduction of music. It was the AR-3 that was the first loudspeaker that used the ‘acoustic suspension’ principal for low frequency reproduction. For mid and high reproduction, two special ‘dome’ reproducers, developed by AR, are used. The next step in the evolution was the AR-3a, which brought an improvement in the mid and high, made possible by choice of new materials and techniques, as well as careful dimensioning of these two reproducers. Frequency response, directivity and colouration were positively influenced by this.

Now, after several years of research and development, the AR-3a is improved. Research and manufacturing techniques, drawn from the AR-LST and several other AR loudspeakers, have enabled AR designers to change the acoustic energy response of the AR-3a/Improved to the current insights regarding acoustics.

Maintaining its characteristic properties, a small change has also made the very small colouration in the mid area disappear. The changes just took place in the crossover; other components, like reproducers and their housing, are exactly the same as with the AR-3a.

The AR-3a/Improved has an acoustic energy response, which is more even than that of the AR-3a. With a 2-position switch, a choice can be made for a reflective or damped listening room.

For a reflective space (as is most common) an as much as possible uniform acoustic energy turnover has been selected, assuming an average loudspeaker placement. For a damped space, the AR-3a/Improved, with the switch in the right position, has an even frequency response, measured from the center of the loudspeaker.

The AR-3a/Improved is Acoustic Research’s most accurate loudspeaker, developed especially for music reproduction in the living room. As with every other AR loudspeaker, the AR-3a/Improved has a 5-year warranty.

Acoustic Research International
Tempofoon BV
Kap Hatterasstraat 8
Postbus 540
Tilburg

Steve F.

[RoyC]

It was somewhat interesting and frustrating--both--to see this discussion go round and round as to whether the 3a/Improved had a FF-cooled tweeter or not.

Steve F.

Hi Steve,

Lots of things go round and round in the forum.

I have worked on a number of AR-3a Improveds. They had AR-3a drivers (correct, no ferro fluid in those old 3a tweeters). If AR actually accomplished the improvements mentioned above, it did so with a moderate change to the midrange crossover circuit, and replacement of the pots with a very simple switch arrangement. In fact, it appears to me that the mid circuit and control changes had as much to do with electrically compensating for the removal of the pots as anything else. Subsequent 3a variations, the AR-11 and 3a Limited, had a 3 position switch and variable L-pads, respectively, along with a return to a much closer version of the original AR-3a crossover.

The 3a Improved is a nice sounding speaker, more like the AR-11, but I found the switches not to be as versatile or effective as variable level controls. I also noted the capacitors in the specimens I saw were of the less expensive, small, black and red variety (Callens, I believe), compared to the excellent Sprague Compulytics in the immediately preceeding original 3a. Who knows, maybe the switches were also less expensive than the troublsome pots, and the real improvements were the cost of production, and reliability.

It is always interesting to take them apart, and compare them to the marketing hype of the day.

Roy

[Richard Grayson]

Good morning Gentlemen,

Thank you both for taking the time to help with my queries.

Roy - I will take your advice and wait till the woofers require service before replacing the capacitors. I think that I was secretly hoping that this would be the case! I will use "Restoring the 3A" instructions as my guide and use the PP or Mylar replacements. Is there any particular brand or model that you might recommend?

Steve - With your reference to the 3A improved/FF-cooled tweeter debate. I was not suggesting that the "A23" tweeter was the original tweeter. The original "fried" tweeter was replaced by AR. They obviously replaced it with the "A23" version.

Is the "A23" FF cooled and if so, does it impact on the selection of replacement crossover capacitors?

Regards and best wishes for the New Year.

Richard

[rjr513]

No The 'A23" is not FFcooled,but When I obtained my AR3a Improve I purchased just bare cabinets so when I went looking for tweeters i used the "A24" becuase I already had two of them laying around in my stock driver surplus,with also the Tonegen replacement woofer i also had

[Richard Grayson]

Hi Ron,

Thank you, I thought that was the case but became a little confused when the topic of FF tweeters was introduced to the discussion.

I have attached photos of the drivers for comment or reference.

Regards

Richard

[RoyC]

Roy - I will take your advice and wait till the woofers require service before replacing the capacitors. I think that I was secretly hoping that this would be the case! I will use "Restoring the 3A" instructions as my guide and use the PP or Mylar replacements. Is there any particular brand or model that you might recommend?

Richard,

Be forewarned, requesting opinions about capacitors can lead to heated "discussions".

I mostly use film caps for reliability, but always seek the best value. For me this has meant using Parts Express (Dayton) polypropylene, Erse polyester, Carli mylar, Axon polypropylene, and Madisound "surplus" film capacitors. They all work perfectly, and will be much better than anything currently residing in your cabinets. I obviously do not believe one brand of film cap "sounds better" than another. A voltage rating of 100v or higher and a tolerance of 5% is all you need. Your original caps have ratings of 50v and 10% respectively. Bear in mind you can connect caps in parallel to build appropriate values.

If you do not have a good source for crossover caps on your side of the planet, find an international seller with the best shipping rates. In the US I would compare Parts Express, Madisound, Erse, and Meniscus, and use overall cost and convenience to make my decision.

Roy

[Richard Grayson]

Hi mate,

Thank you very much for your help and advice. I now have a plan and enough information to implement it.

I hope that I haven't opened a can of worms but it will be interesting to follow if I have.

This site has been invaluable to me and I thank everyone involved in creating it, maintaining it and contributing to it. If any member requires someone on the ground here in Australia to help them, please feel free to contact me via this site.

Regards and thanks again,

Richard