IMF owners thread!

Hi guys,

I want to change the capacitors from the bigger cabinet I have, the lovely ALS 40-II. However, upon searching, I could not find someone posting the schematic or a list of capacitors. There are some infos on page 68 regarding on how to change, but nothing else. From what I read, there are some variants of the crossover. However, I'd like to order several capacitors, there won't be an issue if a few remain, but how many and of what value should be highly appreciated.

Cheers!
 
The best option would be to contact Jerry at Falcon Acoustics and take a few photos of the cabinets showing the drivers and the rear Identification panel. This way Jerry can organise the most accurate set of capacitors for you. You are correct that there are a few variants of the ALS-40 ~ MkII etc.

Being a new member and asking for help, it sometimes helps us immensely to know where in the world you are located, maybe you could be so kind and add that to your profile so that it shows. It can be very helpful when members give advice knowing which way to point you to.

Cheers.
 
Unfortunately, the newer KEF B139 SP1044 has a different sized chassis frame compared to the early original oval framed B139
Hey mech986

Thanks for confirming that the B139s that are available through falcon acoustics are different to the ones used on the earlier reference monitors. I wonder why falcon acoustics chose to reproduce that model. Guess it must be that they are used more widely amongst different speaker makers.
 
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It appears that Laminex (NZ) 1934, Formica (1912), and any European / UK equivalent, are all very similar resin based building and decorative surface materials. Use of these as thin board interior surfaces all started in the 50's and blossomed in the early 60's. The only brochure I could find so far on the Monitor III is the US based IMF / Fried written document which lists them as Formica covered, but I'm sure that's almost used as a generic term.

I do wonder why IMF chose to use Formica/laminex for a time there with the MKIIIs ?
 
Hi Andrew,

There's absolutely no sensible reason why Jerry would even consider updating the first original B139. It was always going to be the more commonly used series II unit as that driver was used by so many as OEM and thus this way some of those better known classics can go on for ever and have an upgraded power handling as well.

As far as the Laminex being used would've been based around sealing the outer surface of the timber cabinet and adding density thus making it a tad more inert and not let the sound become coloured, also a fashion thing at the time I'd say.
 
Hello IMF fans!

I just restored these CM2 (Compact Monitor 2) loudspeakers:

IMF CM2 by antennaguru uda, on Flickr

I refinished the cabinets to overcome some wear and tear, while trying very hard to keep them as close to original as possible. I bought a replacement capacitor set from Falcon in the UK and installed/upgraded the crossovers with the new capacitors, and inverted the woofers 180 degrees to mitigate potential suspension sag (though none was evident as such) during re-installation. I also replaced the rotten front panel cosmetic foam that covers the resistive slot openings with fresh open pore filter foam. I was happy to find the internal foam in excellent condition. They sound as good as I had expected too.
 
WRT the use of Formica and other rigid laminate "veneers", Formica is a very good stiff cabinet finish which is extraordinarily robust from a wear and tear perspective, and it also stiffens a panel made of a softer core material like fiber-board or particle-board when it is applied as an outer laminate.

I built many sets of speakers using wood-grain Formica on their sides back in my speaker building phase, and found that it was an attractive durable surface for loudspeakers. Most importantly those loudspeakers always sounded great, and they also stayed attractive because they were so very durable that someone could handle them roughly during a move/storage, and even put a cigarette out on them and not leave a mark. Leaving a sweating beverage container on a Formica surface would never leave a mark - unlike so many veneered cabinets you find with stains on their tops. Back at that time using Formica was actually more expensive than using wood veneer, plus you needed to own more advanced tools to work with such a hard tough laminate.
 
Fantastic Result !!

I've always been of the opinion that the later IMF's had much improved timber work utilised on them, also the matching of veneers was much more advanced in the twilight production of IMF..

Looking at the result would I be correct in saying that these have been sprayed and if so what products did you use in the process, eg. sanding sealer ? Final clear coats ? etc.

Once again an absolutely lovely example of a fabulous speaker.

PS. can you advise as to which country you are located in ? Am I correct in saying the US ?
 
Thanks for the stoke!

I am based in New England (Northeast US).

As to the finish, I received these a little roughed up and very dry in patches, with white paint scuffs from possibly bumping white painted walls, general light stains, and small scratches, etc. The first step was to deep clean the veneer, so I got the wood even dryer using Isopropyl Alcohol on mild (fine) abrasive 3m (non-metal) refinishing pads, with the grain. That got off the white marks and evened up the tone to just super dry all over - but evenly so. Then using white cotton cloths I padded on Tung Oil finish with the grain to re-moisturize and seal the grain. Several coats were applied with one full day of drying between coats. For the very last step I used a tinted wax pencil on the few deeper marks that remained, and then buffed those mends.

They are not consecutive serial numbers so they are not mirror matched grain veneer, but close enough and certainly very presentable now. The drivers are original, and the original crossovers were fully functional, and just in need of re-capping due to age. Jerry at Falcon Acoustics in the UK was AWESOME to deal with on the caps, and they came very fast! Having been deep inside I can state that these are very well made speakers, and actually designed to be serviced!

They are sitting on sturdy 24 inch steel and cast iron based stands, which I think is about the right height. I notice now in the background of where I took the picture they are temporarily placed in front of my Stainless Steel Conical Fermenter I use for brewing wine...

This CM2 model is particularly interesting to me because I have had a long satisfying experience with "2 way 8 speakers" as a general a class of speaker (2 way speakers using an 8 inch woofer and a tweeter crossed over beyond 2.5 KHz). These actually use a 3 KHz phase coherent crossover and more obviously they use an in-line physical arrangement of the two drivers. They do image very well. What is unusual about the CM2 is the resistive aperiodic loading of the woofer, versus a transmission line design, a tuned port design or a sealed acoustic suspension design. They do have very satisfying bass for a speaker that is only 18 inches tall.
 
The April 2018 issue of Stereophile has a review of an almost exactly the same size cabinet "2 way 8 speaker" called the Harbeth 30.2 - 40th Anniversary. The Harbeth 30.2 current MSRP is $6500. Some differences between the two 2 way 8 speakers are that the Harbeth is not phase coherent, and that it's cabinet is tuned for resonance over a narrow frequency peak via a small undamped port (the fashion ever since Thiele and Small parameters could be easily modeled on a simple computer, or via an on-line calculator http://www.micka.de/en/ ).
 
Tung Oil finish is a broad category of oil finish that is hand padded onto the wood with the grain. It goes on like a simple teak oil for furniture that restores color, but the difference is that Tung Oil hardens fully after it soaks into the grain. It is a relatively green product as far as finishes go, and has been around a long time.

Fornby makes a good Tung Oil finish with no coloring agent, and Watco makes what they call Teak Oil with a slight coloring agent, and those two products are about the tops in my book.

https://en.wikipedia.org/wiki/Tung_oil
 
Just chiming in with the comments on tung oil. I have used tung oil over the years in various projects from sealing bamboo fly rods to sealing the outside of my bee hives with good results. True tung oil is a natural product from the nut of the tung tree. Woodworkers use it too finish items that can be used with food products ie wooden bowls etc.. as it is food safe. Not heard it being used for speaker restorations but result is fantastic antennaguru!
IMF_pioneer if you are interested in a local supply of tung oil sceneys make it. Never use the tung oil from the big hardware stores as they have nasty chemicals in it.
 
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I have a set of Celestion SL6 speakers that I picked up a while ago and one had an open circuit tweeter. I was contemplating parting them out as the cabinets were in dire need of a full surface refurbishment, but I held off on doing that until I knew what was happening with the original "copper dome" tweeter.

Well the tweeter was rescued using some fantastic micro surgery by a good friend of mine that's into high end audio repair work. Now it's my turn to do the cabinet work and bring these beauties back to their brilliant looking and sounding best.

They have already been sanded back and had their small defects repaired, but now I'm a tad stumped as I was going to give them two coats of sanding sealer and then after blocking them back, two final coats of "Mirotone" satin finish Furniture Lacquer.

I'm torn between what I know works and is an industry standard and something I've never done before apart from using finishes like this on outdoor furniture.
 
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IM
I have a set of Celestion SL6 speakers that I picked up a while ago and one had an open circuit tweeter. I was contemplating parting them out as the cabinets were in dire need of a full surface refurbishment, but I held off on doing that until I knew what was happening with the original "copper dome" tweeter.

Well the tweeter was rescued using some fantastic micro surgery by a good friend of mine that's into high end audio repair work. Now it's my turn to do the cabinet work and bring these beauties back to to the brilliant looking and sounding best.

They have already been sanded back and had their small defects repaired, but now I'm a tad stumped as I was going to give them two coats of sanding sealer and then after blocking them back, two final coats of Mirrortone satin finish Furniture Lacquer.

I'm torn between what I know works and is an industry standard and something I've never done before apart from using finishes like this on outdoor furniture.

Is the cabinets on the celestion SL6 made from american walnut? If so get some veneer locally and try it out with both methods and see what you are happy with.
I have some American Walnut if you cant get some locally and can post to you.
 
Hi Andrew,

Thanks for the offer but I'll probably go down the Mirotone road as I have all the products on hand and just waiting for some warmer weather to arrive as it's bitterly cold and wet at the moment, pretty much like it would be for you as well.

Cheers.
 
Hi Andrew,

Thanks for the offer but I'll probably go down the Mirotone road as I have all the products on hand and just waiting for some warmer weather to arrive as it's bitterly cold and wet at the moment, pretty much like it would be for you as well.

Cheers.
I have a friend that's off skiing at Perisher (NSW), while in the US it's as hot and humid as it gets here on the other side of the world...
 
Hello IMF fans!

I just restored these CM2 (Compact Monitor 2) loudspeakers:

IMF CM2 by antennaguru uda, on Flickr

I refinished the cabinets to overcome some wear and tear, while trying very hard to keep them as close to original as possible. I bought a replacement capacitor set from Falcon in the UK and installed/upgraded the crossovers with the new capacitors, and inverted the woofers 180 degrees to mitigate potential suspension sag (though none was evident as such) during re-installation. I also replaced the rotten front panel cosmetic foam that covers the resistive slot openings with fresh open pore filter foam. I was happy to find the internal foam in excellent condition. They sound as good as I had expected too.

Nice work !! i have the same speakers that had blown caps , I have pics in this thread somewhere .

May I ask where you got the foam from and what type it was? I need to do mine.

Nashou
 
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