8 Ohms tweeter, Pots or L-Pads, AR-3a Limited

[mluong303]

Hi, Tom

Thanks for the verification on Polypropylene cone.

Hi, Ed

The AR TSW-610 was the earliest batch which had charcoal grey open cell sponge foam for acoustic blanket which look similar to the blue one used by Duntech speakers and the speaker grill frame was made out of metal rods. The 610A had thick felt for acoustic blanket and plastic grill frame. As far as the sound quality and drivers and crossovers, they are basically the same. They are exciting sounding speakers, very transparent high, well defined and crisp midrange to go with the tight and snappy bass but missing a little bit of low end extention compare to the AR-3a speakers.

In the mid ‘80, AR had pretty much lost its edges and the adverage HiFi consumers were not too exciting about AR speakers anymore. Smaller high end speaker companies growing like mushrooms in the forest and two main compatitors JBL and Infinity really going strong with the 1” titanium dome with diamond pattern embossed on the dome from JBL and the ribbon EMIT tweeter and EMIM midrange of the Kappa series from Infinity. In order for AR to survive and holding up with others in the industry is to come up with a speaker line completely ground up and stay away from the AR-3a shadow. The solution was the Titanium Solid Wood TSW series speakers. The mid ‘80 was a fun era of Laser disc technology fully mature with lots of music video, Movies with Dolby Pro Logic and Karaoke all around the world... The AR TSW speakers fit in the bill perfectly and last for a decent 5 years of production life spend. AR did a lot of homework through research and development to come up with the TSW series and they didn’t forget about the low distortion, wide dynamic range and accuracy reproduction of the AR philosophy. In short they are higher efficiency, slightly brighter sounding but still very well balance overall speakers. The special rounded trapazoid faceplate and acoustic lens of the tweeter have special meaning to it, not just for fancy looking. There was a whole page of explanation about this tweeter. Unfortunately I throw away and loss a lot of AR info over the years from moving so I have no way to provide the discription!

Minh Luong

[Guest postjob62]

Thanks again Minh for sharing your considerable knowledge! Your description concurs with what I said in my original post comparing it to the 3a:

>>>The extreme highs seem a bit more pronounced in the TSW-610's, and the lows may not be quite as authoritative. All in all I don't think the 610 has quite the balance of the 3a, but they sound nevertheless very similar to me.<<<

Except you put it in more accurate terms! It seems to me a very tight, focused speaker that is very pleasing to listen to.

Ed

[mluong303]

I am not associate with AB Tech Services or Mr. Alex Bassoti and I will not get any freebie by saying the following:

If you need any AR replacement drivers or service parts, you should try them first since they have been working as the AR factory service center since the very beginning and I believe they are the one who place orders of the parts from over sea and distribute to other venders in the US. They also offer parts for Advent and Jensen etc.

Check out the following link to find out the availability of what you need:

http://www.abtechservices.com/pages/2/page...h=1134188465692

Minh Luong

[mluong303]

There are two types of 11" foam surrounds available in the US market. The narrower half roll on the left in light gray is available for at least 25 years ago and the wider half roll in darker gray on the right is newer stock available in the US market for the past 5 years ( There was another expensive wide half roll foam surround available in Hong Kong made in Japan around early '90 but were long gone years ago!) Both styles will fit perfectly on AR-11 and AR-TSW 610 woofers. The newer style is very close to the AR-3 cloth surround dimension therefore likely to work better on the original AR-3a and AR-LST woofers. This is just my personal interpretation and I would let the end users decide for Him/Herself of which one to purchase.

For Upgrading Polypropylene Capacitors, beside Solen, Axon from Zalytron are very reliable and cost a bit less. Check them out to see if you want to save few bucks. They are both made in France. I am not associate with Zalytron and Elliot but just want to let the Forum's members know of the available option.

www.zalytron.com

Minh Luong

[dynaco_dan]

Hi Minh;

Thank you for the great advice.

[mluong303]

The way AR used to handle upgrading AR-3 to AR-3a or just servicing AR-3 speakers was to simply cut the plastic grill wide open and then plied and removed the plastic grill frame from the inside. Whether the plastic end up broken to pieces or any imperfection marks will be covered up after the new AR-3 or AR-3a speaker grill is in place and leave the outside wooden frame look as new. There are so much glue all around the AR-3 and AR-1 speaker grills, It will be impossible to remove the speaker grills from the front without leaving some marks no matter how careful one will try!

By looking at the back of the pictured AR-3 speakers for the discolored back panels and the paper labels, these speakers have definitely stored in non climate control storage room for a long time so the glue on the speaker grill edge may have been dried out and the nylon grill material shrunken and pull itself inward and cause the bottom plastic frame to cave in which looks like someone had been plied out the speaker grill. I had seen quite a few original AR-3 with such problem and they had never been open before and in the worst cases was both top and bottom look like what it is in the picture and the middle plastic bar separated from the plastic grill and bent toward the drivers. These are a rare pair of Cherry veneer AR-3. I don't know the seller and just express my observation.

Minh Luong

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[mluong303]

If anyone willing to pay to own the ultimate Crown Reference I or II amplifier then here is your chance for a good deal from Parts Express.

 The Ultimate in Sonic Fidelity. Engineered for the critical demands of recording studios, the Studio Reference Series amplifiers are more than a new benchmark for precision amplifiers and will totally redefine your expectation for studio amplification. They're an investment in long-term performance that anticipates and achieves the next step in professional audio demanded by studios and serious audiophiles. Featuring an extremely wide dynamic range capable of accurately reproducing digital recordings, combined with super low harmonic and intermodulation distortion, these amps provide the best transfer function in the business. They also feature a damping factor of better than 20,000 for absolute speaker control with a tight, well defined low end. Sonic accuracy is just one of the advantages of the Studio Reference as the patented ODEP® circuits detect and compensate for any demanding load condition. THX® certified.

   

   Specifications for REFERENCE 1: * Power output: 800 watts into 8 ohms, 1,190 watts into 4 ohms (per channel, stereo mode); 2,375 watts into 8 ohms (bridge-mono mode) * Input connections: Balanced 1/4" phone jacks on chassis and female XLR connectors on standard PIP module * Output connections: A pair of color-coded dual binding posts for each channel * Dimensions: 19" W x 7" H x 16" D (4 rack spaces) * Net weight: 60.69 lbs. * Power requirements: 120 VAC, 60 Hz - Includes 10 AWG power cord with a special NEMA TT30P plug and matching receptacle.

http://www.partsexpress.com/pe/pshowdetl.c...r=245-450&DID=7

    Specifications for REFERENCE 2: * Power output: 360 watts into 8 ohms, 565 watts into 4 ohms (per channel, stereo mode); 1,145 watts into 8 ohms (bridge-mono mode) * Input connections: Balanced 1/4" phone jacks on chassis and female XLR connectors on standard PIP module * Output connections: A pair of color-coded dual binding posts for each channel * Dimensions: 19" W x 7" H x 16" D (4 rack spaces) * Net weight: 56.13 lbs. * Power requirements: 120 VAC, 60 Hz - Includes 12 AWG power cord with NEMA 5-15P plug.

http://www.partsexpress.com/pe/showdetl.cf...tnumber=245-455

Personally I love it but I can't afford it even back in the early '90 of $4000 list price with 15% off from Canal HiFi, the Crown authorized dealer in NYC! Crown power amps are famous for their reliable performance and built like a Tank quality on top of the tremendous powers output, not to mention the high damping factor which is favorable by the original AR 12" woofer. The best known Crown Amp in the '80 to mate with AR-3a and AR-LST speakers was the Crown distinctive series PSA-2 or the Amcron SA-2 marketed in the Far East, not the earlier 150 or 300 models.

Minh Luong

http://www.classicspeakerpages.net/dc/user_files/1179.jpg

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[mluong303]

AR-3a has always been crowned as "the King of speakers" back in early '70 in the Far East and it is the speakers that started me to get so crazy about Acoustic Research speakers ever since...

If you happen to own a nice pair of AR-3a speakers in decent working order, you should consider yourself lucky to own such a made in the USA Classic with unique sound that many around the world have fall in love even up against today's standard of speaker technology...

The less parts you will change in the AR-3a speakers the better they will hold their value in the collector market. Ten years ago when Mark Levinson decided to switch from AR drivers to Dynaudio drivers in his Cello speakers. All the DIY AR fans like to follow his direction as well. At the time, Dynaudio drivers were not that expensive and you can buy them from any speaker drivers stores. Madisound was the big seller for Dynaudio drivers. There were actually a Dynaudio tweeter and midrange that fit very well into the AR-3a drivers opening. Brian at Madisound may recall the model numbers? However they are not simply drop in replacement since crossover modification was needed. At the time Madisound did provide the crossover modification services for a cost. Layne Audio also had an expensive Dynaudio upgrade kit for AR-3a speakers as well. The bottom line is does it worth the money and efforts for this upgrade to the well known Classic speakers you may no longer call AR-3a anymore!

Few things that need attention in AR-3a speaker are:

1. Foam surround on the woofer need to be replaced.

2. 2 pots need to be disassembled, cleaned and lubricated.

3. Measure if the capacitors value are out of spec? Change to polypropylene caps if needed. If you are not handy with soldering iron, you may cause more damages in the crossover than helping it, so beware!

4. Replacement AR drivers can be purchased from AB Tech Services in MA.

Minh Luong

[Guest Lorin Hollander]

Sorry If I have posted this the wrong forum.

Hello .

I own a pair of Cello Double Amati Speakers used within a Cello system – Performance-II Amps, Palette Preamplifier etc. These are the early Amati version which used the stock AR3-a and LST drivers manufactured (and later imported) by AR in the mid to late 1980s early 90s. Recently I blew all 16 tweeters when overdriving an Allsop sweep test CD! Talk about learning the hard way. The Double Amatis' overall performance had been seriously deteriorating over the past few years - most rapidly in the past months - long before overdriving them while testing. They exhibited an ever increasing high frequency emphasis (and even distortion) - shrillness, shattering, hissing on high voice and strings both on CD and analog. Everything became unbalanced with excessive high frequency nastiness and glare. (This could be do in part to the sun baking on the tweeters overly much.) I have tested and worked on the other equipment in the system and they do not appear to be the problem. (I am a ham radio operator and know my way reasonably well around circuits.) It is unlikely that all 4 crossovers (modified from the LST with good components by Cello, as you all know) went bad over the past months.

Has anyone had experience with these drivers deteriorating and becoming so strident they become unbearable? All 16 tweeter part # are AR 2000084-0 printed on a sticker which reads “Made in USA”. Two of the midrange were changed out between 1990 – 1996 by Cello, one which was distorting and another physically damaged in a move.

The 14 original Midrange drivers are - AR # 200010-1 (again “Made in USA) and the two later models read AR # 1210010 - 3A (331TNH). The latter two do not read “Made in USA, have their part number printed on the side of the magnet and are probably already imported. These interestingly enough have the inch wide black “surround” disk circling the dome made of a thicker plastic material.

I have read with great interest the wealth of information you have bequeathed to us in these posts, and am very grateful. I have discovered myself in a noble company of AR enthusiasts who face a huge challenge when attempting to replace these drivers. I really understand the problem - fine used drivers are rarely available, and new substitutes such as from AB-Tech can be an unknown quantity at best. AB-Tech is currently backordered awaiting shipment from Culver Tonegen, drivers manufactured in Taiwan. What are promised to be NOS are available from Regnar, but I imagine all of us would not be searching for replacement possibilities if the Regnars were acceptable.

I am in contact with one of the original designers of the Cello speakers and he took apart one of my blown tweeters and found that “…there is some foam used underneath the dome that has dry rot.” He advised totally rebuilding the speakers with other drivers. Cello or course “upgraded” to Dynaudio drivers, models now unavailable, and rebuilt the crossovers and baffles. Mark Levinson also advised finding another brand of driver.

So here I am where we all seem to be. Is there a consensus on the bottom line - what AR 3a/LST replacement drivers are the best to use as replacement tweeters? I have read in these posts the understandably differing opinions, and I ask what you believe the best alternative to be.

I have been encouraged to change the midrange drivers as well, but I know how difficult they would be to replace.

I have been a professional classical musician for 50 years and lave lived with the sound of live music all my life. I hope to return these speakers to the way they once sounded. I am grateful for any advice.

Peace.

Lorin

Should I also post this elsewhere?

[ar_pro]

Holy cats! Welcome to the Forum - I've had the pleasure of attending a number of your concerts over the years, and they've always been among my favorites.

Just a suspicion, but since there's been little (maybe no?) mention of deterioration in the midrange drivers on the AR Forum, it seems very possible that direct sunlight may have caused the problem.

I believe Minh Luong is most familiar with the Cello systems, so I'd wait for his reply.

[mluong303]

Hello Lorin

Sorry to hear what had happened to your Cello Amati speakers! I am leaving town for the next week and a half but I will be in touch after I get back and see if I can help you out. In the meantime please email me directly through mluong303@aol.com and let me know what did you do to cause this disaster?!

For your information, Cello tweeters were custom order by Mark Levinson and manually built by AR. They were modified AR-11 tweeters with AR-3a paper domes to hold the original AR-3a tweeter sounding characteristic but the voice coils were ferro fluid filled for higher power handling...

Minh Luong

[Guest Lorin Hollander]

This is a brief thank you, I will be back with a more comprehensive post. Thank you, AR PRO for your insightful suggestion. I believe this may be key. Although I keep the speakers covered most of the time, the sun has indeed baked on these midrange drivers and while the domes look intact and pristine, the surrounding donut shaped frames look degraded. There is also a bubbling up of some foam or glue from underneath this surrounding material on a few of the midrange. Since we live on the coast of Maine there is also noticeable fog and high humidity in the room during warmer weather (all 2 weeks of it) . Have you heard of such sun caused degradation in sound quality?

Minh, I know you are traveling. You know, it Is fascinating, I never get the same answer as to what drivers Cello used in these units. Mark told me they were specially made for him by AR, his co-creators tell me that are “stock AR3-a / LST drivers.” Thank you for addressing an abiding mystery for me and alerting me of the AR11 drivers. . I will be back in touch with you. Please email me to let me know when you return (lorinh@aol.com). I am grateful for your care and interest. Have safe travels.

Thank you all,

Lorin

[Guest Bret]

>There is also a bubbling up of some foam or glue from underneath this surrounding material on a few of the midrange. <

Is there any chance of your uploading a digital photo of this?

Bret

[mluong303]

These 10¡±woofers belong to the Allison One speakers I fully restored and owned for a while but end up letting them go two years ago! Picture below that is re-foam job on the AR-3a woofer.

Minh Luong

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[mluong303]

>> Purchase Solen 3.9uF 250vdc to pair up with Solen .1uf 630vdc and the 5.6uf 250vdc to pair up with the .33uf 630vdc and you are pretty much ready to swap out the caps in the AR-2ax speaker. Don¡¯t waste money on Hovland caps since you are not likely to hear any difference with the AR-2ax drivers! <<

Solen is a big Company specialized in manufacturing capacitors. They can easily produce the exact 4uf and 6uf capacitors if they wanted to. Instead they are making the 3.9uf and 5.6uf so to give you a chance to save some money by just buying a much smaller value but higher power handling bypass cap of your choice (Brand name) to get that little bit of extra high frequency transparency at the end. That is the whole idea behind the fact whether you buy this thinking or not is totally different story! So it is not about matching up the actual cap value to 10% or 5%.

In America, we can buy the 3.9uf 225vdc Zen cap to mate with the .1uf 600vdc Crescendo and a 6uf 225vdc Zen cap to finish the job in the AR-2ax. This way it will be a bit more expensive than the Solen combo but it maybe worth it for the people who prefer the North Creek Music¡¯s crossover components? The bottom line is to pay for what you are comfortable with and does the whole process make sense to you and at the end will you be able to appreciate or hear the difference? Please don¡¯t do it because Minh said so or because your friends think so!!!

http://www.northcreekmusic.com

Minh Luong

[mluong303]

If you are living out West and can pick these Allison IC-20 combo Home Theater set up, it is definitely worth looking into and consideration. I don¡¯t know the Seller but just letting the Forum members know of their availability. eBay Item number: 9738753511

People who own either AR-LST or Allison One speakers often wonder which the better sounding speakers are and does the Allison One end up to be the winner since they are the newer design and built by Mr. Roy Allison¡¯s own company. I feel both models offer equally great sounding classic acoustic suspension speaker designs. Their final sounding characteristics have a lot to do with the room they are in and their placement as well. The Allison One has better driver placement and offer nicer focus sound field and the two 10¡± woofers with 30% more woofer area definitely out do a single 12¡± woofer in the AR-LST. By lowering the dual woofers to the floor to take advantage of the floor and back wall boundaries effect was discovered and pioneer by Roy Allison that had never been talk about in the previous speaker designs. I used to own both models and like both equally well even thought the AR-LST is much more famous and known around the world compare to the Allison One due to the legendary AR-3a and later the expensive Mark Levinson¡¯s Cello Amati speakers.

The Allison IC-20 speakers should be the speakers rated above the Allison One and the AR-LST for their built quality and advance electronics and design concept. The remote control allows the listener to listen to only the inner panels, only the outer panels or combination of all 4 panels. The design and placement of the two 10¡± woofers are different from the original Allison One with one woofer face inside the cabinet and the other face outside. More detailed description can be found in the Allison IC-20 brochure in the Forum Library.

Minh Luong

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[dynaco_dan]

Hi Minh;

Exceptionaly nice photos of a great classic speaker, in exceptionaly nice cosmetic condition, thank you, Minh.

[mluong303]

Correction: The IC-20 HT speaker system is located in North Carolina. My mistake, I thought I read they are located at California when I see the auction first posted?! You just have to contact the Seller to find out where he is for sure...

ML

[JKent]

>Solen is a big Company specialized in manufacturing

>capacitors. They can easily produce the exact 4uf and 6uf

>capacitors if they wanted to. Instead they are making the

>3.9uf and 5.6uf so to give you a chance to save some money by

>just buying a much smaller value but higher power handling

>bypass cap of your choice (Brand name) to get that little bit

>of extra high frequency transparency at the end. That is the

>whole idea behind the fact whether you buy this thinking or

>not is totally different story! So it is not about matching up

>the actual cap value to 10% or 5%.

>

>In America, we can buy the 3.9uf 225vdc Zen cap to mate with

>the .1uf 600vdc Crescendo and a 6uf 225vdc Zen cap to finish

>the job in the AR-2ax.

Hello Minh,

I'm not a technician, just a hobbyist who is combining his enjoyment of hi-fi with his passion for tinkering with gadgets and working with wood, so please excuse an ignorant question: Is the .1uF Crescendo really needed with the Zen caps? I have Zen caps on order for my 2ax rebuild project and have been getting a LOT of very helpful advice from knowledgeable forum members. I thought the +/- .1uF was insignificant, especially given the closer tolerances of modern caps vs. the originals. Am I missing something?

Thanks.

[mluong303]

Hi Kent,

Since you are ordering the Zen Caps for your AR-2ax restoration project, the better person to answer your question would be Mr. George Short of weather the .1uF Crescendo bypass cap is necessary or make any difference in term of sound quality. Also beware of the grey and black lead wires on the Zen Caps are directional. This is the kind of things like cables and amps issues. If you are a believer, they will sound a little bit difference. Otherwise forget about it and don¡¯t bother with it.

There is no need to call the people who believe in them nasty names and order them to prove what they believe in with equations and listening test results etc.! After all the only person who should be happy at the end is yourself with your own set up to listen to your kind of music. Music and HiFi equipments are only a hobby to me and I have a lot of fun with them. Cables and Caps are accessories and they sure are fun and a good way to spend or waste your money depend on how you looking at it¡­

I generally don¡¯t like to mess around with vintage speakers unless they don¡¯t sound right. I am staying with the old saying if it is not broken, don¡¯t fix it! If I meant to keep the particular pair of speakers to myself, I would spend few extra bucks for the bypass caps and be done with it and just enjoy the music rather then keep on wondering if the speakers may sound better if I have that bypass cap added in the first place. In your case, I would suggest you to install the Zen Caps and listen to your AR-2ax speakers and if your music sounds good enough then you can stop there and forget about the bypass caps to save yourself a few bucks. I am comfortable with Axon Caps since I can buy them locally and feel they are equivalent to the Solen Caps in terms of reliability and quality consistency.

Minh Luong

[Shacky]

I just purchased exsact 4.0 and 6.0 Solen caps from Madisound.com. Got the lead from audiokarma. I was looking at the Hovlands but could justify the cost - I'm doing 4 2ax's.

I also ordered 8 ohm l-pads (or potenitometers) from Parts Express. I was trying to rationalize the 8 ohm over 15 ohm wchis is about 4 times the price. I saw a post from Carl saying that the way to check the original unit in the speaker is to measure with a multimeter - and it should go from 0 - 15 ohms. That got me thinking that all this is doing is putting a resistance to the Midrange and Tweeter from 0 -15 ohms. So the 8 ohm won't redue the output as much as a 15 ohm but I'm thinking it should have nothing to do with the overall sound - as long as you didn't want to reduce it by more that the 8 ohms which I don't think I'll want anyway - my 50-year old ears need more midrange and tweeter not less.

Does this make sense?

[mluong303]

Potentiometer or Pot is different from L-Pad. John O'Hanlon had explained this in his posts in the AR Forum. Unless the 4 pots are broken or burned beyond repaired, don¡¯t just switch them out with new 8 Ohms 15w L-Pad. I used to think they are the same also since the people I know say they are interchangeable. In order to keep the electrical characteristic of the original AR speaker crossovers, the original pots are the components to stay with.

Minh Luong

[dynaco_dan]

Hi Minh;

Thank you for bringing this up.

Can someone post the thread that information is on, please.

I am interested in learning more about this issue.

I have heard or rather read that some folks are removing their pots and installing L pads.

Also 8 ohms rather than 15 ohms, also lower wattage ratings.

Perhaps this thread should end here, and be re-started with a part 2 perhaps, it's getting really too long to read, since the dates are not sequential.

My memory is not what it used to be, but, I still remember how discoloured some fibreglass insulation was up against the original pots.

If it wasn't so much work to remove the rear of the original pots, I would remove them and rivet a slug of aluminum to the rear of the metal cover for a heat sink.

Thanks again, Minh for mentioning this issue.

[mluong303]

Roy Champagne is another person who explained in details the difference between Pot vs L-Pad.

The bottom line is that "pots" (short for potentiometers; also known as rheostats) are not the same as overpriced 8 ohm l-pads¡­

The 8 ohm l-pad alters the crossover impedance, especially in the 4 ohm rated AR-3a, and does alter the sound of that speaker. Many folks are OK with that, or do not know any better but it is not the "same" sound. The 8 ohm rated AR-2ax would be least affected by the use of 8 ohm l-pads.

A true replacement is a 15 or 16 ohm pot/rheostat.

The 2ax is rated as an 8 ohm system and may not suffer greatly from conventional 8 ohm l-pads. It doesn't take much in the way of impedance changes however to alter the sound of a system.

The action of the old 15-16 ohm pots keeps the circuit impedance lower than an 8 ohm l-pad. The higher impedance of the l-pad can lower the crossover point and make the old AR tweeter (typically protected by nothing but a single cap) more vulnerable to low frequency damage. This is a greater potential problem when using an 8 ohm l-pad in a <4 ohm system like an AR-3a. It also alters the original sound due to lower frequencies reaching drivers with the new l-pads.

[dynaco_dan]

Great write-up, Minh.