Joel Posted September 4, 2012 Report Share Posted September 4, 2012 I just picked up two pairs of MST's. They are the same speakers mentioned in this thread: http://www.classicsp...?showtopic=7385The first pair seems to be original, while the other pair appears to have replacement woofer. I'll pull them apart later and see whats inside. They sound very different from each other, but both pairs have issues with the tweeters not working.I would appreciate any help or information I could get with these.These pics are the more original looking pair. Link to comment Share on other sites More sharing options...
Joel Posted September 4, 2012 Author Report Share Posted September 4, 2012 These are the pics from the second pair. Also, a picture of them with my other AR speakers.-Joel Link to comment Share on other sites More sharing options...
Joel Posted September 4, 2012 Author Report Share Posted September 4, 2012 I opened up one of the second pair. Definitely not original AR woofers- they are made in Taiwan. The crossover looks pretty simple. Any ideas on why the tweeters don't work? On two speakers the tweeters don't work at all. On one of them, one of the three works. The fourth has all three working tweeters.I hooked them up and gave a listen. They are pretty muted sounding, but I suppose that is because of the tweeters. My AR-4x are far superior. The pair with the replacement woofers just plain sound bad.-Joel Link to comment Share on other sites More sharing options...
ar_pro Posted September 4, 2012 Report Share Posted September 4, 2012 Have you tried isolating each driver, and applying a mid-frequency test signal?With non-original woofers, and most of the tweeters out of action, it's probably too soon to draw a conclusion on the MST's performance. Link to comment Share on other sites More sharing options...
Joel Posted September 4, 2012 Author Report Share Posted September 4, 2012 I am going to concentrate on the first pair for now. It looks like the woofers have been refoamed at some point. However, when they were put back in the polarity of one of the woofers is backwards. The terminals aren't marked- is there any way of telling which is +/-?One speaker seems to be working on all the tweeters, the other isn't working on any of them. I have sprayed them with deoxit, so I will try again later.As you can see from the pictures, the crossover is a little different on this pair. The switch is more accessible on this pair.-Joel Link to comment Share on other sites More sharing options...
Joel Posted September 5, 2012 Author Report Share Posted September 5, 2012 It appears that I have one fully functioning speakers. I think the tweeters are blow on all the others. I'm not sure what that means for the longevity of the working tweeters. So what I am left with is one good woofer, and three cabinets. Any ideas what I should do with them? Maybe sell them for parts? Are replacement tweeters available at a reasonable cost?-Joel Link to comment Share on other sites More sharing options...
michiganpat Posted September 6, 2012 Report Share Posted September 6, 2012 to test woofer polarity: use a 1.5V battery (i.e. a AAA thru D). hook the plus side up to one terminal, the minus to the other. if it moves out, then + on the battery is hooked to + on the speaker. if it moves in, then + on the battery is hooked to - on the speaker.I'd verify continuity of each tweeter with a multi-meter at each tweet's terminals. the fact they are ALL not working makes me think it's a crossover component (resistor, switch, or cap) causing the issue. Link to comment Share on other sites More sharing options...
Joel Posted September 6, 2012 Author Report Share Posted September 6, 2012 Thanks Pat- I've got the polarity of the woofers straightened out. I went through all nine non-working tweeters, and I don't get a reading on any of them. The working tweeters read correctly.I suppose these tweeters are impossible to find. Were there any other AR speakers that used them? Is there a modern equivalent that would work?-Joelto test woofer polarity: use a 1.5V battery (i.e. a AAA thru D). hook the plus side up to one terminal, the minus to the other. if it moves out, then + on the battery is hooked to + on the speaker. if it moves in, then + on the battery is hooked to - on the speaker.I'd verify continuity of each tweeter with a multi-meter at each tweet's terminals. the fact they are ALL not working makes me think it's a crossover component (resistor, switch, or cap) causing the issue. Link to comment Share on other sites More sharing options...
michiganpat Posted September 7, 2012 Report Share Posted September 7, 2012 you went through them out of the box, not connected to the xover?the tweeter is the same pn that is use in the 6,7,8,17,18,25 and very similar, if not the same part number as what was used in the 18S, 38S, 93,94,18B,28B,red box II and rock partners...IIRC the original part number is 1200014-x, and the later tweeters are 1200034-x & 1200038-xwith the -x just being an engineering revision to that part number Link to comment Share on other sites More sharing options...
Joel Posted September 7, 2012 Author Report Share Posted September 7, 2012 I took them out of the box to test them. I have 9 out of 12 tweeters dead and 2 out of 4 dead woofers. These speakers must have speakers must have lived a rough life. I'll keep an eye out for replacement tweeters, maybe I can get a working pair from them.-Joelyou went through them out of the box, not connected to the xover?the tweeter is the same pn that is use in the 6,7,8,17,18,25 and very similar, if not the same part number as what was used in the 18S, 38S, 93,94,18B,28B,red box II and rock partners...IIRC the original part number is 120014-1, and the later tweeter is 120038-1 (what the B's and rock partners use for sure) Link to comment Share on other sites More sharing options...
Joel Posted October 1, 2012 Author Report Share Posted October 1, 2012 I've decide to part out one of the MST pairs. Out of the four speakers, I got one good working speaker. I am using it as a center channel on my TV.If anyone is interested, the pair I am selling has good cabinets and grills. All the drivers are shot. Make me an offer. I will ship but it would probably be expensive. Otherwise I live in the Twin Cities, Minnesota.-Joel Link to comment Share on other sites More sharing options...
genek Posted October 2, 2012 Report Share Posted October 2, 2012 Weren't the Tonegen service replacement woofers made in Taiwan?As for the tweeters, I suggest you check on Carl's testing of the phenolic ring tweeters being offered as AR-4x replacements. If they work well any crossover mod he determines they need may also be applicable to MSTs. You might be able to get the other speakers up and running without making a huge investment in them. Link to comment Share on other sites More sharing options...
RoyC Posted October 2, 2012 Report Share Posted October 2, 2012 Weren't the Tonegen service replacement woofers made in Taiwan?Japan...and have a "TNG" in the serial number.The woofers seen in the photos of Joel's second pair in post #2 are not AR.Roy Link to comment Share on other sites More sharing options...
quebecois59 Posted October 2, 2012 Report Share Posted October 2, 2012 Humm, isn't there enough good material on these MST grills to cover my 2ax's, lol? Link to comment Share on other sites More sharing options...
Joel Posted October 2, 2012 Author Report Share Posted October 2, 2012 I have someone interested in the parts speakers- I'll know by next week. The other non-working speaker just needs tweeters- three of them. The woofer on that one is original and still working. If I could find a good deal on them I would turn them back into a working pair. For now, the single speaker works pretty good as my center channel.-Joel Link to comment Share on other sites More sharing options...
genek Posted October 2, 2012 Report Share Posted October 2, 2012 I'd be trying to put a pair together and use them as the surrounds. Seems others have the idea as well.http://www.polkaudio.com/products/LSiM702fxhttp://www.klipsch.com/surround-speakers?gclid=CNeSsPT74rICFWXhQgodwwQA2w Link to comment Share on other sites More sharing options...
michiganpat Posted October 3, 2012 Report Share Posted October 3, 2012 watch ebay.....there's a ton of the 1200038-x tweets on there right now for a decent price. and there's these woofshttp://www.ebay.com/itm/Acoustic-Research-AR-TSW-8-ohm-woofers-NOS-Qty-2-/280615180459?pt=Speakers_Subwoofers&hash=item4155f7d8abwhich might not be too bad in the parts pair Link to comment Share on other sites More sharing options...
ra.ra Posted October 24, 2012 Report Share Posted October 24, 2012 Hi Joel:I've been following this thread intermittently since your first post, where you made reference to a thread I had initiated regarding MST's a few weeks prior. Full disclosure: I had my eye on this CL ad in the twin cities even slightly before ironlake informed the CSP community on 7.30. I had some preliminary contact with the seller, but then decided to postpone any further pursuit as I was then about to embark on a road trip for a couple weeks. Just for information, the original CL post is attached here.Subsequent life detours obviously kept me from resuming my pursuit of these speakers, but when I saw your post announcing the purchase, I thought, "Good, at least someone snagged these." Without having known the details, I felt there had to be at least one good pair between the four cabinets and multiple drivers. However, my enthusiasm began to fall nearly as fast as yours as I began to read of your discoveries of the many non-working and non-original drivers. I became a bit confused as I followed your inventory count, but it sounds as if, out of 16 drivers total, maybe you have two good AR woofs and 4 good original tweets.If so, I would strongly urge you to try to find two more good working tweets to at least be able to restore one complete pair of MST's. As michiganpat points out, there are several similar 1-1/4" tweeter part numbers that should adequately serve as replacements, and they are not all that difficult to locate and obtain for a reasonable price (see second attachment showing 038 tweeters).The pic of your growing collection was interesting - - - looks like some huge AR-9's in the back and some 4x's with black cloth on the floor serving as temporary stands for the MST's. Let us know how things are working out - - - I'd love to see you get at least one great pair of speakers out of this deal. Link to comment Share on other sites More sharing options...
dynaco_dan Posted October 25, 2012 Report Share Posted October 25, 2012 Hi thereI believe the black bodied, red end capacitors are usually bad and must be replaced for the tweeters to function at all.It would be interesting to have an opinion of the sound differences between the 3 and 4 tweeter MST versions. Link to comment Share on other sites More sharing options...
Joel Posted October 25, 2012 Author Report Share Posted October 25, 2012 Just an update on the MST's. I sold the pair with the replacement woofers on Audiokarma. The guy who bought them found that four of the six tweeter had broken wires on the tweeters. He told me how to check them, but I haven't gotten around to it yet. Those wires are tiny, so I would welcome any suggestions on how to approach them. Meanwhile, I have been using the one good MST as the center channel for my TV, and it works really great.I changed the caps in the pair of MST's that I kept, but it didn't do anything to bring back the non-working tweeters.In the meantime, I have completely rearranged my listening areas. I moved my AR9's into a larger space and they have benefited greatly from the move. I also found an Kenwood KR-7200 receiver to use with my AR4's, and they have been great together. Your right- I have replaced the grill fabric on the AR4's, but I kept the original in case I ever want to switch back. I've attached a few pics of my new arrangements.-Joel Link to comment Share on other sites More sharing options...
ra.ra Posted October 25, 2012 Report Share Posted October 25, 2012 Glad to hear this is starting to work out for you ..... and that Kenwood is probably a real nice complement for the 4x speakers. Is that a Crown amp you're using for the AR-9's?Despite your unmet expectations with the cap replacement, you were smart to get rid of those original black/red Callins caps. And those tiny lead wires on the tweeters - - - yeah, they are very delicate and I've understood that repair requires a sure and steady hand if soldering is required. Even if you're unable to repair the two tweets, I'd still urge you to pursue a pair of used replacements to create a working pair of speakers. Quite possibly more than any of the other classic AR speakers, it strikes me that the 3-tweeter MST, because of the asymmetrical arrangement of drivers, is strongly intended to be used in a left/right two-channel stereo environment. Keep at it - - - without all that much work, you can get the other MST up and running, too! Link to comment Share on other sites More sharing options...
michiganpat Posted October 25, 2012 Report Share Posted October 25, 2012 fwiw, there's a pair of 1200038-x tweets on ebay right now for about $20 shipped Link to comment Share on other sites More sharing options...
Joel Posted October 26, 2012 Author Report Share Posted October 26, 2012 The amp for the AR9's is a Crown XLS-1000. I like it a lot- it is better than the Dynaco 416 that it replaced. I am also using a Nikko Beta II preamp. I have a Kenwood RC-95 that I use to add remote volume control. I think it works fine, but I am considering replacing it with a Emotiva preamp. There is a discussion about my system here:http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=7364-Joel Link to comment Share on other sites More sharing options...
Mar Posted November 9, 2012 Report Share Posted November 9, 2012 Hi guys, just saw this interesting thread. What a score. You probably already know anyway however I came across this site that sells AR parts for the classic Acoustic Research speakers. Hope it helps: http://www.abtechservices.com/arspeakers.html Link to comment Share on other sites More sharing options...
dynaco_dan Posted November 9, 2012 Report Share Posted November 9, 2012 Hi thereThe new drivers are a dropin replacement driver, in some cases, with different sound characteristics than the AR OEM drivers. Link to comment Share on other sites More sharing options...
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