AR3-a / LST Bottom line - Which repalcement Drivers?

[Guest Lorin Hollander]

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.

[johnieo]

>I believe Minh Luong is most familiar with the Cello systems,

>so I'd wait for his reply.

Minh is away with family until about 24 April; he should be able to provide lots of detailed information, if you would please wait until he returns.

[Guest Lorin Hollander]

Thank you John. I am looking forward to being in contact with Minh.

All best.

Lorin,

[Pete B]

Hi Lorin and welcome to the board,

Based on your post it sounds as if your open to new and better drivers rather than a purist rebuild and I see advantages to each option. In any case please save your original drivers, just in case you don't like the results as they can sometimes be repaired.

It would be good to know your goals which may not become clear until you get a better idea of the available options.

If I read you correctly it sounds like your getting the advice to move to better drivers probably based on the thinking that it is what Levinson did when he later used Dynaudio drivers. It would help to see the crossover schematics for both versions. There might be other Amati owners who'd like/need the upgrade to the later Amati version when/if their drivers fail and it might be good to have a company who can do the mod competently and correctly. I'd be willing to reverse engineer the Dynaudio based Amati crossover if the crossover schematic is not available, and if someone provides a sample, say a pair that are being opened to have the crossover caps checked, or something similar.

It would help to see close up photos of both the tweeter and mid in your speakers so that we can see some details. I assume that they're all the same appearance wise? I just noticed that your mids are the standard AR type used in the AR-11, which I measured in this post:

http://www.classicspeakerpages.net/dc/dcbo...ing_type=search

You could probably find replacements on ebay from late production AR-11s, if you wanted to get back to all original type midranges.

I spoke through e-mail to the folks at Speaker Bits who seem to be the only ones carrying Dynaudio and he said they'd be bringing back the D21AF. This didn't happen. Dynaudio is an interesting option since there was a version of the Amati that used them. You'd of course want to have the crossover updated, if there were any changes. One of the distributors such as Madisound might do a special sale for you given the fairly large quantity of drivers that you'd be buying. They do have replacement parts and do repairs on Dynaudio drivers:

http://www.madisound.com/cgi-bin/index.cgi...10.8840&pid=233

Interesting questions.

Minh has used the current replacement tweeter as you've probably noticed from his posts and picture, but as you mention the tweeters were slightly different in the Amati. I'm also curious to hear what Minh might suggest.

Pete B.

[Guest Lorin Hollander]

Hi Pete, thank you for you welcome.

You wrote:

>Based on your post it sounds as if your open to new and better drivers rather than a >purist rebuild and I see advantages to each option.

…. Yes, in this case. I know well the purist commitment. I recently restored a 46 year old amateur radio Collins KWS-1 Transmitter and 75A-4 receiver, replacing every component with original parts – where possible.

.… With the Amatis however, since these are not vintage AR-3-a or LST the intention is different – to do what ever is necessary to achieve the most glorious sound, yet avoiding modifying the baffles or crossovers at all, or if absolutely necessary, then as little as possible. A truly first class “drop in” would of course be best.

…. The question is what AR drivers did Cello use, I get many different answers to this question even from those who designed the speakers (see my original post above) and I have received some very informative advice from other members. The tweeters are all the AR 200084-0 drivers. Different than AR-3a drivers. One very helpful member believes that the AR 1210084-0, available at Simply Speakers would be the closest I could get to these drivers, and that they are the Chinese version replacing the 200084-0. the only confusion is that dry-rotting foam was found under my tweeter domes.

>> In any case please save your original drivers, just in case you don't like the results as they can sometimes be repaired.

… Yes of course, the midranges still are in very good shape. The center donut shaped covering surrounding the dome is peeling away on the early models AR # 200010-1. the two newer 1210010 - 3A midranges all have fully intact surrounding material.

>>It would be good to know your goals which may not become clear until you get a better idea of the available options.

.. As above: to rebuild the speakers for the best possible sound with the minimum amount of modification to baffle (or crossover – which is very different from the XO in the LST) - To go with the finest drop-in replacements available.

If I read you correctly it sounds like your getting the advice to move to better drivers probably based on the thinking that it is what Levinson did when he later used Dynaudio drivers.

Yes and no. The Dynaudio speakers (D21AF), as you say below, are no longer available – unless that has changed. A friend explored with me replacing the tweeters with the DynAudio Esotars, and the midrange with inexpensive but wonderful Peerless drivers. But this would mean massive baffle changes, a totally recreated crossover with no guarantee of total coherence. So again, I have opted to find the finest drop-in replacements – if such an animal exists, and if not - I am willing to modify the crossovers somewhat to align with other drivers.

It would help to see the crossover schematics for both versions.

…. I have checked with Mark Levinson and Paul Jayson, and neither have the schematic for either the AR or DynAudio crossovers.

>> There might be other Amati owners who'd like/need the upgrade to the later Amati version when/if their drivers fail and it might be good to have a company who can do the mod competently and correctly.

>> I'd be willing to reverse engineer the Dynaudio based Amati crossover if the crossover schematic is not available.

…. It is a good idea, and we even need a reverse engineering of the AR-based Amati crossover (which I could do myself), as the difference with the LST is so extensive. There are for instance no Electrolytic cans, - but rather 21 RIVA caps – all on a large circuit board.

>>It would help to see close up photos of both the tweeter and mid in your speakers so that we can see some details. I assume that they're all the same appearance wise?

…. I have taken the photos and will upload them when time permits.

>I just noticed that your mids are the standard AR type used in the AR-11,

…. Are both the AR # 200010-1. and the two newer 1210010 - 3A midranges used in the AR-11s? What midranges are used in the AR-3a – LST, I have forgotten.

…. I am looking for the best possible midranges, I know this is a tall order.

>>Dynaudio is an interesting option since there was a version of the Amati that used them. You'd of course want to have the crossover updated, if there were any changes.

… There were major changes, and the crossover is the easier part, the baffle changes are extensive and would need rebuilding.

Thanks for your interest, Pete.

Best

Lorin

[Pete B]

Hi Lorin,

Just so that I understand - baffle issues, it seems to me that the AR drivers are large such that usually a reducer adapter would be needed for a clean fit. This could be machined from aluminum and painted or anodized black. Ideally, an all new aluminum face plate could be fabricated removing the stock plate from the selected driver and installing it in place. This is possible only with drivers where the dome/voice coil is not mounted to the face plate. Short horn loading can be eliminated with a flat plate in some circumstances, I have done it many years ago, not with ARs.

Do you run your speakers with the grills on? This would make an adapter even less of an issue.

I don't know if you have a strong interest in the Dynaudio drivers, but if you do Madisound works with them and might be able to make a special order. It is interesting that they were also full exposed dome drivers. I'd expect it was the 2" for the mid?

Do you know if the differences between the AR version and the Dynaudio are well known and documented? Is the Dynaudio version positively better?

I'm not sure which Peerless mid your speaking of? I did casually suggest the 821615 some time ago. Looking again at it and knowing more about the AR mid, it is an excellent match - Fs and Qt are about right at 530 Hz and .72. It is a true 8 ohm driver, with ferro fluid so impedance matching and probably crossover changes might be required. It is back in stock at Madisound. This driver is used in one of the most popular entry level "high-end" speakers, and also a multi-thousand dollar boutique speaker. I have four of them.

If you asked me for the best, 1.5" dome replacement I'd probably say a modified Scan Speak 1.5", since they use advanced motor designs and are known to handle low crossover points, however mid 500 is very low so some testing would be in order and mods to the venting and chamber might be required.

I have an interesting low cost driver in mind as a midrange replacement, and have them on order. Let me do some tests first before I suggest it as a replacement.

Also, are you interestted in altering the tonal balance in anyway? Revoicing as they call it, or are you happy with the balance and want the new drivers to keep them clean with low distortion?

I see speaker improvements/design as an interesting challenge and would enjoy helping if I can.

Best Regards,

Pete B.

[Guest Lorin Hollander]

Hi Pete,

I am going to wait until I speak with several friends who own Amatis to be guided in the next steps.

I am grateful for your interest and creative ideas.

Til later.

Lorin

[Pete B]

Hope you keep us posted as to your progress.

Pete

>Hi Pete,

>

>I am going to wait until I speak with several friends who own

>Amatis to be guided in the next steps.

>

>I am grateful for your interest and creative ideas.

>

>Til later.

>

>Lorin

[Guest Cliff]

Hi Lorin and everyone else,

I hope this thread is still active and I can be of some use. I saw this thread while searching Amati's on google and I just had to sign up so I could respond. I also own two pairs (double-stacked) Amati's. First, a little background, I am currently a DVD producer and have worked in many post houses in the past and have been fortunate to be in the right place at the right time when they upgrade equipment. We had the fortune of having these double-stacked Amati's installed in our main edit bay by Mark Levinson himself back in the early 90's. About a year and a half ago, our company moved to a new building and my supervisor asked me if I wanted them. I didn't hesitate. They were missing all the grills (because they were behind a speaker grill wall in the edit bay), some of the tweeters had dented dust caps, one tweeter was blown, they had some screw holes in the bottom so they wouldn't topple over during an earthquake (yes, we are based in SoCal) and the foam around the woofers was...well pretty much gone. So I restored them.

The one place that actually knew what I had just by looking at the drivers and woofers were the ones that helped me, Orange County Speaker Repair (www.speakerreapir.com). They have the foam surrounds for the woofers in stock and it only cost me $45 a woofer. They also had AR driver replacements in stock and sold for about $90, the only down side is that they were made from the new tooling and look slightly different but they are made to the same specs as the originals and fit right into the cabinet, screw holes aligned and all.

My original part # on my blown driver is 200083-0, I don't have a part # for the replacement, sorry.

Now with my speakers rebuilt and running, (part of my audio only system) I am extremely pleased with the work and service from OCSR.

So, if you're still interested, you might want to give them a call.

Keep us posted as to your findings.

Cliff

[Guest Americain]

Hi Lorin,

Not to go off topic or anything but remember those great ads for AR in the early 1970's that featured great artists like Seiji Ozawa and others? The black and white ones done in very classy black and white? I can totally see you in one of those ads. Ahhhh, if only...

Welcome to the board Lorin. Lots of great info here.

Thom

[Pete B]

This gentleman builds some fine speakers with some of the finest drivers available. He likes the Dynaudio D21 better than the Morel Supreme, however, I don't think it was a controlled test:

http://www.madisound.com/cgi-bin/discuss.cgi?read=378627

His web site:

http://www.gattiweb.com/delta_mkII.html

Pete B.