AR Midrange 200032 modified as 200044

[Giorgio AR]

I have a 200032 mid belonging to my pair of AR58s that presented a complete fracture of the ceramic magnet.
Despite the break, the midrange worked, although with less sound emission than the other mid., The coil of this midrange is good, with a detected resistance of 3.2 / 3.3 ohms.
I purchased a midrange 200044 belonging to AR92, apart from the color difference of the front flange (two-tone brown / silver), electrically and physically the two midrange are identical; the detected resistance of the 200044 mid is 3.2 ohms.
I could replace the malfunctioning speaker with the new purchase, but I didn't like the aesthetic difference of the couple.
I had to paint the new mid in matt black, otherwise I would not have been satisfied with the purchase.
I sanded the mid flange with 1200 grit sandpaper, cleaned and degreased the flange, masked the screw holes and the lower part of the flange with tape and built a 53 mm mask. for the dome (made by properly cutting a plastic cup and taped to the support).
The painting was done with two coats of paint for plastic in matt black.
Apart from a small aesthetic defect caused by the difficulty of painting near the dome, the final result is excellent, making this 200044 mid indistinguishable from the 200032 that it replaces.I still have a doubt, I could even replace the label indicating the model and date on the back of the magnet, but I think that to avoid confusion I will leave the original labels in their place, welcome advice on this last point!

Giorgio 

 

Original 200044 mid

 

 

Fractured magnet

 

200032 replace mid

2000

 

both mids

 

Velcro removed

 

sanded flange

 

painted 200032 mid

 

200044 vs 200032

 

Dome mask

[ra.ra]

Hi Giorgio, your work looks very good and is a simple and clever adaptation for cosmetic purposes. One small correction - - you seem to have the drivers mixed up - - the 032 midrange was used in the AR-92 while the 044 midrange was used in the AR-58s. More importantly, however, is that you have correctly noted that functionally, these two drivers are fully interchangeable among these 3-way speaker models.

The plastic face plate that you have painted is termed the "semi-horn" on all of AR's fabrication drawings. There is a third AR mid-driver from this family that is very closely related and nearly identical - - part no. 200028. The 028 mid is found in the AR-9 and AR-90 - - both 4-way speaker models - - and the only physical difference is the amount of ferrofluid which affects its lower limit crossover point.

A brief summary of these three mid-drivers:

• mid p/n 200044 - - model AR-58s - - above 700Hz - - horn p/n 204096 - - color: all black
• mid p/n 200032 - - model AR-91 and 92 - - above 700Hz - - horn p/n 204085 - - color: brown w/silver paint
• mid p/n 200028 - - model AR-9 and 90 - - above 1200Hz - - horn p/n 204079 - - color: black w/silver paint

For future reference, I'm pretty certain that the plastic semi-horn can be fairly easily removed from the robust metal parts of these drivers. I seem to recall seeing on these pages a very clever project where RoyC adapted one of these drivers for use in an AR-3a or AR-5 cabinet. In that instance, I believe he removed and abandoned the original plastic horn and - - for cosmetic purposes - - replaced it with a domed screen grille cage that is typically found on the mid drivers for the AR-3a and AR-5 speaker models.   

[Giorgio AR]

Ra.ra I'm sorry for the delay in my response, but on Thursday afternoon I left for an extended weekend of holidays and I went to the beach in a Dalmatian island, this morning the last swim (practically me and my 7-year-old son were the only ones in take a bath in late autumn) and I had no possibility of using the internet. Thanks for your attention, your reply is very welcome because it gives me a lot of additional information and also the confirmation of having found a compatible midrange for features to the original one, but unfortunately with broken magnet and sound emission much lower compared to the mid of the other AR58s.
I purchased this 200032 mid as it is more readily available than the AR58s mids (there was some time in Italy selling a mid 200044 specimen, about $ 55 the price, but I gave up buying at the time).
So I decided to buy a 200032 mid and perform an aesthetic makeover to make it visually the same as the replaced speaker.
One of my doubts is also to invert the small identifying labels so as to make it indistinguishable from the original, but in this way I would make a fake!
I gave up on making this replacement, also because the label can only be found by removing the speaker and in any case I keep the original mid between my spare parts.

Giorgio

[ra.ra]

13 minutes ago, Giorgio AR said:

One of my doubts is also to invert the small identifying labels so as to make it indistinguishable from the original, but in this way I would make a fake!

What you've done with paint on the frontside seems perfectly fine for your intended purposes, but it was also a good decision to not make the change on the rear label. By doing so, you could have easily lost track of not only that driver's origin, but also its date of manufacture.  

[Giorgio AR]

Ra.ra,I have to congratulate you for your competent, very explanatory interventions, you are a great help like a lighthouse in my opinion !!!!

Giorgio

[teknofossil]

On 10/31/2019 at 11:55 AM, ra.ra said:

Hi Giorgio, your work looks very good and is a simple and clever adaptation for cosmetic purposes. One small correction - - you seem to have the drivers mixed up - - the 032 midrange was used in the AR-92 while the 044 midrange was used in the AR-58s. More importantly, however, is that you have correctly noted that functionally, these two drivers are fully interchangeable among these 3-way speaker models.

The plastic face plate that you have painted is termed the "semi-horn" on all of AR's fabrication drawings. There is a third AR mid-driver from this family that is very closely related and nearly identical - - part no. 200028. The 028 mid is found in the AR-9 and AR-90 - - both 4-way speaker models - - and the only physical difference is the amount of ferrofluid which affects its lower limit crossover point.

A brief summary of these three mid-drivers:

• mid p/n 200044 - - model AR-58s - - above 700Hz - - horn p/n 204096 - - color: all black
• mid p/n 200032 - - model AR-91 and 92 - - above 700Hz - - horn p/n 204085 - - color: brown w/silver paint
• mid p/n 200028 - - model AR-9 and 90 - - above 1200Hz - - horn p/n 204079 - - color: black w/silver paint

For future reference, I'm pretty certain that the plastic semi-horn can be fairly easily removed from the robust metal parts of these drivers. I seem to recall seeing on these pages a very clever project where RoyC adapted one of these drivers for use in an AR-3a or AR-5 cabinet. In that instance, I believe he removed and abandoned the original plastic horn and - - for cosmetic purposes - - replaced it with a domed screen grille cage that is typically found on the mid drivers for the AR-3a and AR-5 speaker models.   

 

[teknofossil]

Ok, with your supplied info the differences between these two mids is basically the damping applied via ferrofluid. Other than the diffuser grill assembly, any idea as to the differences between the mid units used in the  AR10 /11 series the AR91 and the AR92?  Damping?  

[ra.ra]

It seems I may have confused this issue by introducing mention of the third mid-driver - - - to reiterate, it is the 028 mid that is different from the other two, and it is only found in the larger four-way speaker models. The two mid-drivers used in the three-way models - - the 032 and the 044 - - are fully interchangeable and identical with the exception of the color(s) of the plastic face plate (semi-horn).

The dome mids found in the AR-10π and AR-11are indeed different drivers from the 032 used in the AR-91 and 92. I am not able to describe the differences, but I think this topic has been discussed in other threads in this forum.

[Kal87bmw]

Will the 200044 work in the ar 9 even though there not correct I just got a pair of 9s and that’s what’s in there or should I try to find the 28s. Thanks for all the great insights 

[Stimpy]

1 hour ago, Kal87bmw said:

Will the 200044 work in the ar 9 even though there not correct I just got a pair of 9s and that’s what’s in there or should I try to find the 28s. Thanks for all the great insights 

The 200044 domes will work fine in AR-9's.  The 9's, with their LMR woofer, don't require the UMR bandwidth, that's required for 91's, 92's, or 58S's.  So, you're good as is.

[Giorgio AR]

On 11/3/2019 at 11:14 PM, ra.ra said:

What you've done with paint on the frontside seems perfectly fine for your intended purposes, but it was also a good decision to not make the change on the rear label. By doing so, you could have easily lost track of not only that driver's origin, but also its date of manufacture.  

Ra.ra, rereading yours first answer, apart from the classification, the reported differences between the various types of mids useful to clarify the correct use in the speakers that need to replace mid units, I have thought about your statement that RoyC has removed from one of these mid the plastic horn!
I could have done the same and then replaced the two types of plastic horns, it's too late, but now I am going to remove this detail from my 200044 with the broken magnet.
Then I will publish the photos of the removal works and the separate components.
Thanks for the great input
Giorgio

[Giorgio AR]

Done! First I heated the mid at around 40 ° C, then with the dentist's instrument, a small atraumatic spatula, I raised and unglued the double-sided adhesive frame that unites the plastic horn to the mid flange (I think it is the same type used on the AR10 late tweeter and AR11 with the upper foam ring!).
I also measured the thickness of the paper which is 0.2 mm.
Total time for removal (except the additional 20 min. For heating the mid) about 2/3 minutes.
Thank you ra.ra, and I hope this work is useful to the enthusiasts! AR.

Here below the sequence and details

 

 

 

 

 

 

 

[ra.ra]

What you have done with the black paint looks terrific, but if you decide to try to remove the semi-horn from one of these drivers, you should be aware of where the factory adhesive is located. On the partial drawing shown, items 11 and 12 indicate locations of two different adhesives, as noted in assembly note 9. Item 11 is a contact adhesive applied to the wide outer flat surface of the horn; and item 12 is a second type of adhesive located under the narrow inner flat surface of the horn near the dome. This should be helpful if you attempt to pry off one of these plastic horns - - at least you'll know where you are trying to break the bond between parts.

Be careful, work slowly.  

[ra.ra]

Wow, that was quick work! I wasn't even able to reply in the time it took you to dis-assemble this mid driver. That is great work.

It appears that instead of the two-sided contact cement that I had expected based on the assembly note 9, your driver instead used a thin double-sided paper tape for this purpose. Your pics are very good, and in the "naked" pic of the front driver flange, you can clearly see the surround and the inner ring of the second adhesive. Thx so much for sharing - - - now I want to get one of those specialized spatulas!   

[Stimpy]

This makes me wonder if the Simply Speakers UMR dome, is a suitable AR replacement?  I believe they're the dome that KK used in the 303.  Attach the semi-horn faceplate, and they'd appear to be (almost) identical.  Now, I wonder how they sound? 

 

[DavidR]

20 minutes ago, Stimpy said:

This makes me wonder if the Simply Speakers UMR dome, is a suitable AR replacement?  I believe they're the dome that KK used in the 303.  Attach the semi-horn faceplate, and they'd appear to be (almost) identical.  Now, I wonder how they sound?

In a thread I started regarding AR Replacement Drivers RoyC stated that it was NOT a good replacement - Only in a pinch or something to that effect.

I contacted MidWest Speaker who makes a very good tweeter replacement and talked them into developing a replacement Mid driver based on that thread and a couple of others.  They have a pair of AR 200044 mids and will use those to develop a replacement. They said it could take a year or more before we would see them.

[frankmarsi]

DaviR,  would you think they would be as hearty as the original mids from the 1970's?   In my experience, I feel AR's midrange is the best part of the 'AR-sound' besides their 12" woofer.

I imagine they'd be manufactured in China as all have since AR went under.

P.S. When Mark Levinson came out with his 'LST' he used the standard 4 ohm AR midrange with the metal grill absent as he asked AR to make them that way for him. The second iteration of the M.L.  'LST' used midrange drivers by another manufacturer.

FM

[ar_pro]

43 minutes ago, frankmarsi said:

 I feel AR's midrange is the best part of the 'AR-sound' besides their 12" woofer.

This is a good observation. A lot of attention is justifiably paid to AR's acoustic suspension woofers, but the dome midrange is in the DNA from the AR-3, onward, and definitely helps to establish the playback quality that we all appreciate & enjoy.

 

Excellent documentation, Giorgio - this will be a big help to anyone working with these mids!

 

[DavidR]

1 hour ago, frankmarsi said:

DaviR,  would you think they would be as hearty as the original mids from the 1970's?   In my experience, I feel AR's midrange is the best part of the 'AR-sound' besides their 12" woofer.

I imagine they'd be manufactured in China as all have since AR went under.

We can only hope they will be a good match.

Yes, China. They are good at copying things BUT the end results always depends on if they tried to 'cheat' to save a renminbi.

[Giorgio AR]

8 hours ago, ra.ra said:

Wow, that was quick work! I wasn't even able to reply in the time it took you to dis-assemble this mid driver. That is great work.

It appears that instead of the two-sided contact cement that I had expected based on the assembly note 9, your driver instead used a thin double-sided paper tape for this purpose. Your pics are very good, and in the "naked" pic of the front driver flange, you can clearly see the surround and the inner ring of the second adhesive. Thx so much for sharing - - - now I want to get one of those specialized spatulas!   

Hi ra.ra, first of all, in this mid, there is only the presence of the double paper adhesive on the outside of the flange, then if you look at the dome of the mid, after removing the plastic horn, around you see a glue ring transparent often with the shape of the inner ring of the plastic horn that pressed over it impressing the shape: at that point the plastic horn was not glued, adhered only (I think it was left to harden the glue until a certain time to thicken the dome fabric and then later flattened by the addition of the platic horn to perfectly seal the two flanges.
Secondly, I have a wife who works in a dental office and brings me the tools that are no longer in use (because they are old or no longer perfectly functional for the original work), so old spatulas, hooks and special pliers. The beauty of these instruments is the fact that they end up slightly rounded, so they do not scratch or engrave metal, plastic or anything else.
I am attaching photos of some spatulas (these are also very useful for refoaming both to remove the foam from the cone, and to remove it from the metal basket), the instrument below (and in particular) is a small retractor and is phenomenal for: removing the speakers from the baffle, special ones those with sealant like gaskets without ruining anything, and to remove the glued grilles (using the longest side), paired with other spatulas to help!

Giorgio

 

 

 

[Giorgio AR]

8 hours ago, ra.ra said:

Wow, that was quick work! I wasn't even able to reply in the time it took you to dis-assemble this mid driver. That is great work.

It appears that instead of the two-sided contact cement that I had expected based on the assembly note 9, your driver instead used a thin double-sided paper tape for this purpose. Your pics are very good, and in the "naked" pic of the front driver flange, you can clearly see the surround and the inner ring of the second adhesive. Thx so much for sharing - - - now I want to get one of those specialized spatulas!   

P.S: regarding the use of the Midwest midrange, here are the photos of a good use that has been made of this component, the photos have been taken from the auction site.