Jump to content

At 9 lower midrange reconed


Kal87bmw

Recommended Posts

13 minutes ago, DavidR said:

From what I remember the difference is more cosmetic. The 200044 became the AR replacement for the 200028 and 200032.

The 20028 mid had more ferrofluild, than the 200044 and 200032.  The 200028 had ferrofluid on both sides of the voice coil, while the 44 and 32 used fluid only on one side.  This slightly altered the resonance frequency, allowing the 44 and 32 to play lower in frequency, than the 28.  That allowed the 200044 and 200032 mids to better blend with the woofers, in a 3-way design.  Being a 4-way, the AR-9 didn't require the 200028 to respond as low, hence the higher resonance, and hopefully, better power handling, with more ferrofluid in the voice coil gap .

Link to comment
Share on other sites

Very good info Stimpy. I remember Carl posting that the 200028 has half the resonance of the 200032. However, IIRC the 200032 and 44 can be used in place of a 200028 but not the other way around.

What I'd like to know is how they are able to keep the ferro-fluid on one side of the vc.

Link to comment
Share on other sites

We were just discussing the 044 driver in another thread by Giorgio, and it is this paper by Tim Holl which explains the ferrofluid issue which differentiates the mid used in the three-way models (032 and 044) from the mid used in the four-way speakers (028). The entire paper by Holl is a good read.

AR-91 and 92 hi and mid - Holl.jpg

Link to comment
Share on other sites

1 hour ago, Kal87bmw said:

Thanks for the help you guys  it’s nice to have this site  not sure how to post pictures but I’ll try

Pictures will help, as I'm a little unclear as to what's been done to the LMR?  Were the 8" woofers really re-coned, or just refoamed, with incorrect surrounds?  And I would think the cloth surrounds should be replaced, as they won't exhibit the correct compliance, of proper foam surrounds.  Incorrect surrounds can easily be removed and replaced with the correct foams. 

Link to comment
Share on other sites

21 hours ago, ra.ra said:

We were just discussing the 044 driver in another thread by Giorgio, and it is this paper by Tim Holl which explains the ferrofluid issue which differentiates the mid used in the three-way models (032 and 044) from the mid used in the four-way speakers (028). The entire paper by Holl is a good read.

AR-91 and 92 hi and mid - Holl.jpg

Another great piece to understand AR mids, this paper explains in a simple way the evolution, the "universality", the versatility and the greatness of this wonderful instrument, and also because, to date, in the form of a replica more or less equal to the original keeps its charm intact.

Link to comment
Share on other sites

3 hours ago, Kal87bmw said:

They are totally re-coned as well as the 12 in woofers same cone material ribbed paper but they have foam surrounds all magnets appear to be correct 20003 & 200027 I probably got taken but they sound great and I put aside my magnepan 3.6rs  & rel subs

Wow  I really would like to see what those woofers look like. A lot members here are all in on preserving the originality of these vintage speakers which I agree with, but I also believe that sometimes different modifications can be a good thing. Also some times not so good.  Here are my AR9 lower mids that I refoamed last year with slightly different filled fillet Boston type foams.

EXVudyNl.jpgqtoJAEKl.jpg

Link to comment
Share on other sites

It looks as if the drivers were rebuilt by a decent shop.  Even though they didn't rebuild to stock.  So, if the speakers work, and you like the way they currently sound, I'd leave the speakers as-is.  It would cost close to $600 or more, to source the correct woofers.  So, I'd enjoy them, without any guilt, because you still have a fine set of speakers.

Link to comment
Share on other sites

Check the restoration guide, I bet there's nothing like it. I've been staring at AR's fine 12" woofers most of my adult life and have never seen a ribbed one.

Could've been a replacement kit? The VC cap looks over-sized also. I've seen horror stories on the auction where some folks can be handy with a hack-saw and will squeeze some no-name junk in place.

"Kal87bmw" will have to delve into this mystery.

We must consul the AR Gods.

RoyC. where you be?

It's not like years ago when "sound minded" , "johnieo", "SteveF", "PeteB", "DynacoDan", "Minh", and a few others that were knowledgeable for all those years prior.  Now, it's mostly new recruits and learn as you go types. Not that there's anything wrong with that. But, to think my speakers are older than some folks here.

P.S. Correction, I have never seen a ribbed AR 12" newer design woofer in all of my adult life.

Link to comment
Share on other sites

6 hours ago, DavidR said:

A while back I ran across some 12 inch woofers in a pair of 9's that were ribbed just like those. I think they were in N.Y. and the guy said they were original cones. I passed.

Frank and David,

The foam surround/ferrite magnet version of the AR 12  inch woofer in the photo above had a stamped steel basket and a smooth cone (never ribbed). Cone weight and stiffness, spider and surround compliance, and voice coil electrical characteristics are more important concerns than the ribs alone.

The 8 inch drivers do not appear to be AR parts.

Roy

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...