AR1's with the grill off. Altec speaker

[Guest David Rawson]

I've been listening to these old AR-1's and trying to determine if either of the speakers are in need of repair. Although I get no indication of distortion during a frequency sweep from 16k hz to 50 hz, there is a distinct "old" sound to them. The bass response is great, but the midrange is really lacking as far as any sort of presence goes. I was pretty sure that the cones on the midranges had separated from the rims, or something...

So I got the nerve to remove the grill on the unfinished one of the pair as it is located within a larger cabinet that houses the amp. This cabinet has a second grill hiding the speaker and associated tweeter. If I failed and damaged the grill, it wouldn't be seen.

The grill came off successfully and the speaker doesn't show any sign of degredation that I can see. When I lightly push the outer edge of the cone I hear a rubbing sound that sounds like paper, or cone material rubbing against itself. Does that mean anything? Is there any obvious test I could do (or have done) to determine if these are OK? I'm hoping to achieve a full sound from these speakers (and the electrostatic tweeters that were originally paired with them.)

A couple photos are included.

In an earlier posting, it was said that the bass response of the AR1's was superior to the 2a's, but not the midrange. The bass is amazing, but I can't believe the midrange should be as bad as what I'm hearing.

The second speaker in the pair has the same inferior sound. Are there any components in the crossover that might require replacement?

Is there another midrange speaker that could be considered as a superior replacement?

[ar_pro]

That's a heck of a set-up, and an interesting engineering & philosophical problem. Just a guess: the Altec mids & AR woofers are probably fine, and the problem is with the tweeter's power supply, and certain crossover components. If your goal is to have a speaker that sounds better than this system, you could just buy an AR-3a. Or, assuming there's something actually wrong with the drivers or crossover, you could begin the troubleshooting/replacement process, and restore the system to original performance capability - *but* you might not like the final result (the AR-1 is just not as good as a 3, or 3a), although this system was clearly put together by someone who was interested in "the state of the art", circa 1957 - those electrostatic tweeters and add-on crossover demonstrate this. Even if you were to sell the system, it would almost certainly be broken up, with the Altecs parted out to Asia, where they hold high value.

[tysontom]

>I've been listening to these old AR-1's and trying to

>determine if either of the speakers are in need of repair.

>Although I get no indication of distortion during a frequency

>sweep from 16k hz to 50 hz, there is a distinct "old" sound to

>them. The bass response is great, but the midrange is really

>lacking as far as any sort of presence goes. I was pretty

>sure that the cones on the midranges had separated from the

>rims, or something...

>

This sort of sums up the sound of the AR-1's Altec 755A midrange/tweeter: it is relatively accurate, but it lacks presence and extended off-axis response because of the size of the driver and the rolloff above 13 kHz. Any driver that becomes directional at the upper extremes will sound dull in a room, no matter how uniform its on-axis response. Add to that the fact that the on-axis sound rolls off above 13 kHz in the 755A, and you are going to hear a very reticent sound in the treble. That might be intepreted as "old" sound. And like you say, the bass response is great, because the AR-1's bass is essentially the same as the AR-3, AR-3a, AR-10Pi, AR-ll, AR-LST and so forth. In other words, it is about as good as it gets for anything its size, and then some.

>

>The grill came off successfully and the speaker doesn't show

>any sign of degredation that I can see. When I lightly push

>the outer edge of the cone I hear a rubbing sound that sounds

>like paper, or cone material rubbing against itself. Does

>that mean anything? Is there any obvious test I could do (or

>have done) to determine if these are OK? I'm hoping to

>achieve a full sound from these speakers (and the

>electrostatic tweeters that were originally paired with

>them.)

>

Anytime you push a speaker diaphram from the edge of the speaker, it will deform the cone enough to cause the voice coil to rub, and this would most likely be true of either the woofer or the 755A. Hearing a rubbing sound this way would not be considered unnatural. To see if anything is actually rubbing, the best way to determine this is to gently push the cone in the *center,* using your fingers in a row around the dust cap, and gently push in the cone. The woofer will move a significant amount, but the 755A will only move a little. Neither should make any rubbing sounds when you do it this way. You can also use a sine-wave generator or test disc to use sine waves (the generator is better because you can take it up through the frequencies) to test each driver. This must always be done at very low input voltages so as to not burn out any voice coils or cause bottoming, etc. Start at around 400 Hz., set the levels low, then sweep through the frequencies to see if you can detect any distortion or rubbing.

>A couple photos are included.

The photo of the entire AR-1 with the tweeter does show a very professional, state-of-the-art setup for the late 1950s. There was simply nothing that could be purchased during that period that would out-perform the AR-1/Janzen electrostatic combination.

>

>In an earlier posting, it was said that the bass response of

>the AR1's was superior to the 2a's, but not the midrange. The

>bass is amazing, but I can't believe the midrange should be as

>bad as what I'm hearing.

>

The AR-2a had superior treble, not necessarily superior midrange. Both the AR-1 and the AR-2 had relatively large midrange drivers, but the AR-2a used the AR-3 dome super tweeter.

>The second speaker in the pair has the same inferior sound.

>Are there any components in the crossover that might require

>replacement?

>

It really doesn't sound as though the AR-1s are having difficulties, but are likely dull-sounding in today's context.

>Is there another midrange speaker that could be considered as

>a superior replacement?

>

During the live-vs.-recorded concerts (1956 I believe) using the AR-1s compared to the Mt. Kisco Church Aeoleon-Skinner organ, the New York Audio League used Bozak 8-inch midrange drivers rather than the Altec 755As. They also used the electrostatic for the high frequencies.

--Tom Tyson

[Guest David Rawson]

My thanks to Mr Tyson and "ARPRO" for the responses. This web site is very helpful in my efforts to get this system working to its full potential. As the photo showed, the system is well integrated into a custom cabinet that my grandfather built so I'm making every effort to conserve all the components. However my goal is to get the best sound possible so it doesn't sit and collect dust as one of the antique music boxes for the new millenium. The remainder of the system is a Dynaco PAS-2/Dynaco-70 amp and Garrard Type-A turntable.

Would it be an insult to purists if I were to locate superior sounding midranges and replace them? Do you think I could succeed in this idea? Although the AR-1's may suffice with the vintage vinyl library that accompanies the system, I would also like to use them as impressive remote speakers with my regular system.

Thanks again for all the info.

[tysontom]

>My thanks to Mr Tyson and "ARPRO" for the responses. This

>web site is very helpful in my efforts to get this system

>working to its full potential. As the photo showed, the

>system is well integrated into a custom cabinet that my

>grandfather built so I'm making every effort to conserve all

>the components. However my goal is to get the best sound

>possible so it doesn't sit and collect dust as one of the

>antique music boxes for the new millenium. The remainder of

>the system is a Dynaco PAS-2/Dynaco-70 amp and Garrard Type-A

>turntable.

>

>Would it be an insult to purists if I were to locate superior

>sounding midranges and replace them? Do you think I could

>succeed in this idea? Although the AR-1's may suffice with

>the vintage vinyl library that accompanies the system, I would

>also like to use them as impressive remote speakers with my

>regular system.

>

>Thanks again for all the info.

Your grandfather assembled a fine system, and you should be proud! He knew exactly what he was doing, and he did it right.

I was wrong about one thing: on closer inspection of your picture, the electrostatic tweeter is the Realistic Model Electrostatic-3, which was an inexpensive version of the Janszen I-30 electrostatic. I never knew if there was very much difference between the Realistic-3 and the Janszen, but the Realistic was much less expensive. The Realistic-3 was also check-rated in Consumer Reports, an important quality endorsement. The Janszen was a true electrostatic tweeter, and was extremely fine and accurate.

Your grandfather's AR-1s were also later versions, as you can see by the ribs and early damping rings on the woofer cone. This happened towards the end of the 1950s, probably 1959 or perhaps 1960. Roy Allison, who started at AR in 1959, worked on this woofer as one of his first projects to make it operate more smoothly in the upper range of its operation, and the ribs added strength to the cone and the foam ring was the first of the damping rings that appeared on the later AR-3 woofer.

I would personally resist making changes to the AR-1, but then again I am a hopeless AR purist. I think that the crossover to the electrostat-3 is rolling off the 755A prematurely, but then the Electrostat-3 is probably not working properly. I totally agree with ar_pro that the problem is likely with the electrostatic unit, its power supply, and if you addressed the issue of the tweeter (even replace the Electrostatic-3 if it is bad), you may find things much more satisfactory. You can sometimes find an AR-3 super-tweeter (AR-3st), or the AR-3 midrange and super tweeter combination (AR-3t) that is made-to-order for the old AR-1. But just about any decent tweeter add-on unit would help tremendously with that setup, and once you restore the high frequencies, then you would never want to part with the system -- both for functional and for sentimental reasons (I would think!).

--Tom Tyson

[Guest David Rawson]

Thank you again.

So what would you recommend for a crossover setup with the tweeters?

I'll bet that's been my problem. Right now I'm using crossovers that send the signal to the Realistic 3A's at 4khz. (Duh!) The literature with the tweeters recommends a 5hz crossover, but I didn't have one. Would a crossover that is more around 13khz be in order? Can you get them?

What did the system that is pictured with the AR-1 gallery under "Picture of AR-1 with Janszen Tweeters" use?

Again, thanks for the information your compliments to my late Grandfather (Some credit goes to my late uncle for the electronics...)

[ar_pro]

The Janszen 1-30 used an internal crossover and level control...it's response was 500-30kHz, and was usually crossed over at the 500 Hz point. This being the case, it seems as if the Altec driver was allowed to roll off naturally, without electronic attenuation. Period literature cites the AR-1 as being down 1.5 dB at 13 kHz, so that crossover point may be a bit high for your Realistic tweeters.

Just a question: Have you tried running the tweeters by themselves? How's their output?

[Guest David Rawson]

I had the tweeters repaired recently as a first step in restoring this system. I brought one to a shop and they said it only required a new rectifier. After the repair, I added it to one channel with a crossover (4 khz) and was satisfied that it was performing, at least better than before taking them to be repaired. With that, I brought the other one to the shop and had it repaired.

Since you asked, I tried the tweeters alone this evening and they don't seem to be putting out much in the way of sound. When coupled with the AR-1's, I could hear high frequencies coming from them, but I guess it wasn't much. Since I immediately set them up with the AR-1's and never tried them alone after being repaired, I really can't say if they have failed again, or were never really up to snuff in the first place. I'll plan to take them back for a re-eval by the shop.

So I guess that's a second "duh" for me! My concern about lack of high frequencies was probably mostly due to the low crossover frequency and tweeters that weren't really working properly.

What is the general opinion concerning electrostatic tweeters: Are they salvagable or would it be more efficient/economical to consider new tweeters as a replacement?

[ar_pro]

The electrostatics of that day were not the most robust drivers around, and a high spl capability was never their long suit. That said, unless they arc out (damaging their membrane), most problems were related to the power supplies. It's a good bet that the defective rectifier was selenium, and it's also possible that other passive components could be damaged or well out of spec...hopefully, the transformers are OK. There's not much going on in that ps...it should be possible to go over it with a multimeter, and check for values, and for consistancy between the two speakers.

Tom's suggestion of an add-on AR-3t is a great idea...you'd be able to keep your grandfather's system intact (just disconnect the Altec), and have the attributes of an AR-3a. Or, just add the AR supertweeter, running with your AR-1 (Altec active), and you'd have a beautiful vintage system!

[Guest David Rawson]

So one last question....

When I do get some sort of tweeters, what is the best way to wire them up? The crossover cut out too much to the AR-1's. I have them back to normal without the crossover and tweeters and they sound much better, but tweeters would provide those last high frequencies.

Is a crossover necessary or can you just let the speakers reproduce whatever they can? (Is that what "ar pro" was refering to when mentioning letting the 755a's roll off naturally?)

Would you wire these in series or parallel?

If a crossover is recommended, what specs would you suggest?

Thanks again

[tysontom]

>So one last question....

>

>When I do get some sort of tweeters, what is the best way to

>wire them up? The crossover cut out too much to the AR-1's.

>I have them back to normal without the crossover and tweeters

>and they sound much better, but tweeters would provide those

>last high frequencies.

If you could find the AR-3st (this is the tweeter-only portion of an AR-3 with the 7500 Hz crossover), you would be able to use the AR-1 up to the 7500 Hz point, and then the dome super tweeter would take over from there. This is a very good combination, because the Altec 755A is a decent midrange speaker up to a point, and the highs would be handled properly from there with the 1-3/8-inch AR-3 dome tweeter. The AR-3st does not cut out the midrange as does the AR-3t, which includes both the midrange and tweeter from an AR-3.

>

>Is a crossover necessary or can you just let the speakers

>reproduce whatever they can? (Is that what "ar pro" was

>refering to when mentioning letting the 755a's roll off

>naturally?)

Yes, you will definitely need a crossover to prevent low frequencies from entering the tweeter voice coil. The tweeter would only last a second or two under power trying to handle full range.

>

>Would you wire these in series or parallel?

There is a specific method to wire the AR-3st crossover to an AR-1, irrespective to series or parallel. You would just follow the instructions, or connect C and 8 on the AR-3st to the amplifier and terminals 1 and 2 on the AR-3st to the AR-1 in the way you would connect it to an amplifier.

As a last resort you could take an AR tweeter such as the 3/4-inch AR-3a or AR-11 or AR-9 tweeter, and use the half-section component of the respective crossover from which the tweeter came, and then mount the tweeter on a small frame on top of the speaker (since the speaker is hidden in another cabinet your grandfather built). Power would go into the tweeter's crossover which would divide the signal between the AR-1 and the 3/4-inch tweeter.

--Tom Tyson

[johnieo]

David: I have a Realistic Electrostatic that I no longer wish to keep, you are welcome to it for postage;l perhaps two out of three will work??