AR MST WOOFERS

[ru040708]

I have owned a pair of AR MST with repaired woofers as photo. I thought the repaired are from AR 18.

As I know that AR 18 is new generation and not as good as old ones, and truely the sound is not the same as original MST I heard.

I have searched for a while for original woofers and AR7 to replace but still can't find one.

Now there is a friend want to sell me a pair of AR6 as photo. Does the woofers fit on MST?

I know the original ones are flat on dust caps and cone, and the color is also different. Does this matters a lot?

[ReggaeBen]

Hi, 

Firstly, the woofers in your friends ar6's are early Alnico magnet and not the more commonly found ceramic magnet like in your MST's.  The ar6, 7, 17, 18, 25, mst (can't think of anymore off the top of my head) all share an 8" woofer although they did have some minor differences to suit the particular speaker it was fitted to.  The first AR18 is seen by many as the slightly better of the 18 models.

Is it possible for you remove the woffer for us to identify?  

Btw, the 6's are a fine sounding bookshelf speaker, you should try them out..

[ra.ra]

Hi ru, and welcome to the CSP forum.

That woofer in your MST has been re-foamed very well, and it also appears to have a new dust cap, but we cannot tell if it is an original MST driver or an AR-18 woofer without seeing the backside (including labels or markings), as Ben has already suggested. The AR-6 woofer will "fit" in the MST cabinet and it will provide sound, but I would discourage this idea for two reasons: the early AR-6 woofer was made for a different speaker with its unique circuitry; and I would hate to see an otherwise excellent pair of early AR-6's become cannibalized for parts.

Pics attached show the physical differences. The AR-7/MST woofer has the smooth cone and square ferrite magnet; the early AR-6 woofer has the ribbed cone and huge alnico slug magnet - - this woofer is at least 1/2" greater in overall depth. Before you pursue a search for replacement AR-7/MST woofers, I'd like to suggest you provide a closer inspection and diagnosis of the woofers currently in your MST speaker cabinets.

What is it about your MST's performance that is unsatisfying?

 

[AR55]

In a previous post it was established that the AR MST ("Woofer", posted 10-26-18)  used the universal 8" AR woofer 200001.  That woofer was used in the following speakers: 4, 4X, 4BX, 6, 7, 15, 16, 18, 25 & 94.  Note that the AR-18 is an ADD series speaker.  Later models (18s, 18b, 18bx & 18bxi)  use different 8" woofer models.  These may or may not have the same sound characteristics as the 200001 model.

If the label on the back of your woofers have the model number 200001, then they should be the correct woofers.  I believe that the 4, 4X, 4BX & 6 had alnico magnets, whereas the 7, 15, 16, 18, 25 & 94 had ceramic magnets.  I am not sure when your MST was manufactured.  If it was made prior to 1974, it probably had woofers with alnico magnets.

 

[ru040708]

I've removed the woofers from MSTs. I think it should be the original  and refoamed.

I visited a man who mastered in AR speaker. He told me the woofers may be original but due to some reason it performed wierd.

He thought the pre-owner had coated some softener on the cone.

The sound is different when we knocked on the cone between this pair and the original MST from my friend.

 

What is it about my MST's performance that is unsatisfying?

The sound performed not so clean but noisy compared with my AR4x. My AR4x sound very soft and loose.

Sorry that I am not native English speaker. Can not describe very accurately.

 

My system is crown M-600 and rep-111C made preamp.

[ra.ra]

2 hours ago, AR55 said:

In a previous post it was established that the AR MST ("Woofer", posted 10-26-18)  used the universal 8" AR woofer 200001.

I think this is fully correct (and would apply to the AR-7 as well). The earliest mention I find of AR's 8-inch "universal" woofer is the 1977 parts list, and I suspect by this time this driver was deemed a suitable replacement for most (or all) earlier speaker models using 8" bass drivers, all the way back to the AR-4 from 1964. Nonetheless, many of the earlier 8-inch drivers (AR-4, AR-4x and earliest AR-6) had very different physical characteristics, and I presume, somewhat different performance response as well.

2 hours ago, AR55 said:

I am not sure when your MST was manufactured.  If it was made prior to 1974, it probably had woofers with alnico magnets.

 I may be mistaken, but I believe that all AR-7's and MST's used the foam-ferrite woofer. I think the earliest AR-6 was the last of the 8-inch alnico, while subsequent versions of AR-6 had square ferrite magnets. 

20 minutes ago, ru040708 said:

I've removed the woofers from MSTs. I think it should be the original  and refoamed.

Thx for the new pics, and your English is very good. Those appear to be the correct woofers - - part no. 001-1 with bright red stickers indicating replacement part from 1982. As stated earlier, the foams on the woofers appear excellent - - not sure there is any need at all to re-foam. Not sure what the problem is with your speakers, but if they sound "not so clean", could it possibly be indicating a need to replace the capacitors used to filter tweeter frequencies? 

Your MST's look like they might be the early four-tweeter variety, which used two different capacitor values.