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Replacing Peerless K040MRF in a set of IMF TLS 50s

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Posted on May 10, 2012 at 09:31:14
Jeffrey88
Audiophile

Posts: 21
Joined: May 8, 2012
 Hey VA,

Well I have stumbled upon a bit of a predicament.

I have picked up a pair of absolutely beautiful IMF TLS 50 II's. I love these speakers to death already. However there is one compromise that I want to fix with these. Luckily, there has been some upgrades made to the crossovers already so I am quite happy with that. The problem is, the midrange drivers are mismatched.

Now, I know that the original driver is a Peerless K040MRF. Amazingly I found a set of these for sale by someone, but I have also found out that these are the closed-can versions. I've heard that the right kind is the open-ended drivers. Being that the open-ended ones are most likely impossible to find, and since I have stumbled upon this set, do you think I would hamper the performance much by going with these? I've checked and the cans appear to be attached and non-removable. The speakers do have the cardboard tube inside them so I'm wondering how this might affect the sound.

I do understand how particular this question is, so I'm mostly looking for some explanation and experience with these drivers and the closed-can concept.

Thanks very much for any help.

 

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RE: Replacing Peerless K040MRF in a set of IMF TLS 50s, posted on May 10, 2012 at 10:49:52
ColinR
Audiophile

Posts: 315
Joined: October 24, 2001
 The "canned" KO40MRF have a set screw underneath the Peerless label on the back of the can.
Remove label, and remove the long set screw; KO40MRF "uncanned"

 

RE: Replacing Peerless K040MRF in a set of IMF TLS 50s, posted on May 10, 2012 at 10:55:05
Jeffrey88
Audiophile

Posts: 21
Joined: May 8, 2012
 For real!?

Oh perfect.. I am definitely getting these then.

Thank you!

Edit:

I was just thinking.. how do these woofers come out of the can? Is it like this:

http://forumbilder.se/images/d54201163245P78d2.jpg

If so, I guess I'll have to find a way to reframe the woofer and attach wiring to the driver.

 

Not quite., posted on May 10, 2012 at 11:07:29
Kal Rubinson
Reviewer

Posts: 12435
Location: New York
Joined: June 5, 2002
 I do not know exactly what is in the TLS 50s but Peerless lists the closed back unit as the KO40MRF and the open back unit as KU45MR. The specs are somewhat different including a larger magnet, higher sensitivity, higher power handling and wider bandwidth for the former.

That said, it may work.

Kal (current owner of the KO40MRFs)

 

RE: Not quite., posted on May 10, 2012 at 11:10:44
Jeffrey88
Audiophile

Posts: 21
Joined: May 8, 2012
 Yeah the information on this is quite sparse unfortunately.

I don't think I'm going to worry over it and give it a shot. At the very least it's going to be an improvement over what I have and that will be good enough. Plus it'll be nice to have at least something close to the original drivers that were in these.

Edit:

It's looking like the Version 1's had the KO40MRF's. Is that true? If so, then these should work just fine..

 

RE: Not quite., posted on May 10, 2012 at 20:37:41
hahax@verizon.net
Audiophile

Posts: 4306
Location: New Jersey
Joined: March 22, 2006
 I believe the first TLS50s(IMF Sudio 1 and 2 - I owned 2s) used a paper cone Elac coated with PVA. The Peerless drivers were used in the IMF Studio 3 and 4 and IMF Electronics TLS50s. You might also try to find later TDL 50 mids that they designed and had built for them. They might work. But there's always the problem of chnge drivers means change crossovers. Good Luck.

I loved my Studio 2s(and a set of Studio 3s with the Peerless mids).

 

RE: Not quite., posted on May 10, 2012 at 20:53:29
Jeffrey88
Audiophile

Posts: 21
Joined: May 8, 2012
 Thanks for your response.

In regards to the crossover, yes, I have thought about that. Unfortunately the way it is right now is there are two slapped in midranges from who knows where. One looks like it's from a set of Realistic Minimus 7's and the other.. well, I can't figure it out. The last owner put these in because the midranges died on him and he did nothing but plug them in and screw them in.

That's why I feel at the very least, putting these in would be a better option than what I've got and the crossover could be changed at a later date. Plus they're fantastic midrange drivers.

 

RE: Not quite., posted on May 10, 2012 at 20:56:01
Jeffrey88
Audiophile

Posts: 21
Joined: May 8, 2012

Here's a picture of the what the originals in this particular set were (based on the fact that the woofer and tweeters are still original in mine):

 

RE: Not quite., posted on May 10, 2012 at 21:04:56
hahax@verizon.net
Audiophile

Posts: 4306
Location: New Jersey
Joined: March 22, 2006
 Those are interesting pictures. They look like my Studio 3s except for the woofers which appear to be KEF B220s which were only used in the Studio 1 and 2 and were I believe were not used in the Studio 3 and later versions.

 

RE: Not quite., posted on May 10, 2012 at 21:14:25
Jeffrey88
Audiophile

Posts: 21
Joined: May 8, 2012
 Here are pictures of my actual speakers.

http://www.canuckaudiomart.com/forum/download/file.php?id=9266&mode=view
http://www.canuckaudiomart.com/forum/download/file.php?id=9264&mode=view

Notice the supertweeters are changed as well as the mismatched midrange drivers. The supertweets were replaced with comparable units so I'm not worried (with crossover sufficiently upgraded at the same time) about those, but I need to fix the midrange issue.

 

RE: Not quite., posted on May 19, 2013 at 14:50:55
paul72@windstream.net
Audiophile

Posts: 3
Location: western NYS
Joined: December 28, 2011
 I just ruined a single K40mrf by trying to remove it from its can. Bummwd, as they used to say. Any leads on geting another? Crumbly surround no problem so long as it works otherwise.

 

I have 2 K40mrf available., posted on May 20, 2013 at 05:57:55
Kal Rubinson
Reviewer

Posts: 12435
Location: New York
Joined: June 5, 2002
 Contact off line, if you are interested.

 

RE: I have 2 K40mrf available., posted on June 18, 2013 at 17:45:39
paul72@windstream.net
Audiophile

Posts: 3
Location: western NYS
Joined: December 28, 2011
 Hello, Kal: Thank-you for responding to my plea for a pair of Peerless KO40MRFs. The originals in the Beovox cabinets are the 4-ohm (so stamped on the cone) version, with a hard plastic can bolted to the rear of the magnet, No actual frame connecting the cone and foam surround to the magnet - odd. ...a bolt attaches the magnet to the can and the cone/foam is glued to the can rim in front ; no intermediate frame to stiffen the assembly. At any rate, I picked-up a pair of the 8 ohm versions-pressed steel can this time-only one survived the trip from Sweden. I installed the surviving 8 ohm single to replace the ruined 4 ohm original, and paralleled an external 8 ohm Peerless 5x7" oval with similar closed-back can with happy results. Nonetheless, I am still eager to discuss the availability of your generously offered spares. Still interested? I apologise for taking so long to respond ; I only stumbled onto your offer while googling once more for an orphaned pair, and found you there tonite - a month later. Do your spares bear any resemblance to mine? Regards, Paul Anderson.

 

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