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IMF owners thread!

Hi, welcome to AK the ribs on the woofer make the cone more rigid, check for the value of capacitors,probably the same like the one on Als 40 MK II kit.Best regards,Yvan.
 
canuckaudiog said:
From what I know about the new B110 is it is made exactly the same as the original B110. Same materials, construction, everything (including the bextrene cone). Regarding doping the cone, I asked Jerry about it and he said it's something worth trying without, so I have ordered them plain for now, and may add the doping later on. I would rather try them without first to see how it is and then add it later on, as it's a permanent decision once it is on there.

Regarding new B110 vs. old B110, part of the reason I decided to do this, even though my original B110s are still OK, is Jerry informed me that they tested dozens of old stock B110s and found them all out of spec. Granted, I have no idea how far out of spec we are talking, but I think the B110 is the most important driver for the IMF speaker since it covers the largest frequency range, so I want these to be in tip top shape. Also, the B110s in my IMFs are likely from the early 70s, placing them close to 50 years old so it doesn't hurt to refresh them since they are available. My understanding is that while it seems like drivers should not degrade, the suspensions in them do over time and this causes them to stop measuring within spec.

I did do some reading about reviews of the Falcon LS3/5a (which uses their new B110), and comparisons to the original Rogers LS3/5a. Many of the reviews reflected that the new LS3/5a sounds livelier and more upbeat, and in general was better all around. How much of this is attributed to the refreshed drivers is difficult to say, but I am sure it is a factor. One thing was clear, though, is that the new LS3/5a is a true, faithful and identical replica of the original, so no modifications or anything like that. Therefore I am confident at least some of the better sound can be attributed to the fact the drivers are brand new.

This also leads me to think the B139 would be similar, however unfortunately the 6171 is not easily replaced by the SP1044. I will have to figure out a way to make that happen as I would really like to put new B139s in my IMFs.
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Back when Kef started manufacturing bextrene cones they were all doped with plastiflex.
viewtopic.php
This was used to tame the resonance problems that resulted with this type of cone material.
Audax, Dalesford, Seas and Focal all doped their bextrene cones with plastiflex.
Dalesford cones using inverted surrounds was one way of taming the resonance issues.

Over time the spiders do wear out on drivers causing the specs to drastically change.
Many of the B110 drivers produced were never up to specs.
This was why so many were rejected for use in the Ls3/5a models.

Gary Galo published some of his findings in the former Speaker Builder magazine.
He found the Audax 5" bextrene cone drivers measured closer to published specs than the Kef B110's.
 
The crossover of the ALS40-IIa is not the same as the ALS40-II. The brochure clearly mentions a "redesigned crossover". The only way to know for sure is open it up and look. The crossover is behind the upper woofer.
 
My Falcon B110s arrived yesterday!

I wasted no time and installed them immediately. First of all, the originals are from 1972. That puts them at 47 years of age, quite old. I bought the new B110s for this reason. Though they still work, it's doubtful they are still operating as they did when new.

I did what I usually did, which is install one and compare it to the original. Using a mono signal and swapping between the two speakers was interesting to say the least. The new driver sounded lighter, clearer and more natural. And, not a small amount either. It was a significant difference. Enough of a difference that I had to recheck my wiring to make sure I had the new one hooked up the same. But, after confirming that, it was obvious the new B110 sounded much better.

Once I was happy with the new B110, I installed the other one and spent some time listening. Wow, I cannot believe the difference! Is this what a B110 is supposed to sound like? Unbelievable. No wonder it has such a cult following. Vocals sound so great now, the murkiness that resided here is gone. The sound field has so much more depth, guitars sound incredible.. the list goes on. I was expecting a difference but not this much. It's like the speaker was recapped (which it already is).

I do think that this difference largely accounts for the age of the driver and it's production run. These are old B110s with silver frames so perhaps the construction materials don't age as well. But either way, I can confirm that this is a very worthwhile upgrade. Should you do it? If you have IMFs from the late 70s, probably. But I can't guarantee the same results since it's impossible to say what working condition yours will be in. However worst case scenario, you end up with a brand new set of B110s and have backups for years to come.

In short, bravo Falcon. I'm so glad I bought these. Now to figure out how to fit the new B139..
 
Hi Canuck,

I guess the end result is what Jerry was always hunting out. Many of the materials within the suspension over the years have hardened and thus restrict the fine movement of the coil and cone. I've always believed in the upgrades that Jerry has done as he wouldn't release anything on to the open market if it wasn't right nor an upgrade.

Personally I've always felt Jerry hasn't received the recognition within the industry he so deserves.
 
IMF_Pioneer said:
Hi Canuck,

I guess the end result is what Jerry was always hunting out. Many of the materials within the suspension over the years have hardened and thus restrict the fine movement of the coil and cone. I've always believed in the upgrades that Jerry has done as he wouldn't release anything on to the open market if it wasn't right nor an upgrade.

Personally I've always felt Jerry hasn't received the recognition within the industry he so deserves.
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I couldn't agree more. Over the past 7 years, Jerry has been a huge support and sounding board for all things KEF/IMF. I learned pretty much everything I know from him, and I have always found his information to check out. For example when I had KEF 107s and I asked for his advice on what to do with the crossovers, he suggested recapping them, even though the originals were pair matched. After doing the work, he was right - they sounded much better after, and that was using the same parts (Alcaps). With IMFs it's the same thing, with the latest being these B110s.

As you said, we tend to think drivers do not get worse with age but this experience has told me otherwise. Not to say all drivers suffer the same, but in many cases it's likely true. What is a real blessing is the fact Falcon Acoustics exists and we have such a gem in Jerry who is on a constant, relentless pursuit of keeping these great things alive. To think, he was able to reproduce the B110, a driver that was in production over 50 years ago, with the assistance of the designer himself. It really is an amazing accomplishment. And now that I'm hearing the B110 properly for the first time, I completely understand the love for this driver and all of the accolades it gets. No wonder Jerry and so many others see the LS3/5a the way they do.
 
Hi, pair of the same domestic monitor like the one Jeff (canuck...) have, with some SP1044 in the baffle,it seems the seller move the woofer placement on one side for him to fill up just the edge of other side.How the sound moving the woofer? But easy job to fit the SP1044. Sell In England
 
Yvan_donald said:
Hi, pair of the same domestic monitor like the one Jeff (canuck...) have, with some SP1044 in the baffle,it seems the seller move the woofer placement on one side for him to fill up just the edge of other side.How the sound moving the woofer? But easy job to fit the SP1044. Sell In England
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I think I know which ones you are talking about. Yes, it looks like the SP1044 was fitted without much trouble. I'd love to see the actual cut-out, to see what I'm up against.
 
Hi, I have an sp 1044 so I will take a picture ,pretty sure the hole (4 screws) are not at the same place.With my extra pair of Prof. mk 3 I have I can check.
 
I no longer have an imf that uses the b110, the super compact 2 uses something else I think, but I have some
Chapman audio system bookshelf that uses the kef b110, it already sounds great can’t imagine it can sound better, might just try it.
 
Hi, so for everyone w ho want to modify their IMF by changing the old Kef woofer SP 6171 (B- 139) for the new Falcon (FB-139) or SP1044 Kef. The cutting hole in the baffle with SP 6171 have the dimension approx. 8 1/8 inch. X approx. 11 9/16 inch. ( curve diam. Approx. 4 1/16 inch.). Holes (4) distance for screws , horizontal approx. 7 1/4 inch., vertical approx. 8 1/2 inch. The dimensions of the frame (basket) for the SP 1044 or FB-139 are 8 5/16 inch. X 11 13/16 inch., so the cutting hole in the baffle have to be smaller, the basket from the edge to the angle (1/2 inch.) all arround., so the cutting hole should be 3/4 inch to 7/8 inch smaller. Holes (4) distance for screws ,horizontal 7 9/16 inch.,vertical 7 7/8 inch. My cutting hole baffle with the woofer is done loose,because the flange is very wide, but for the SP 1044 because the flange is only 1/2 inch. It at to be tighter.Hopefully you understand my writing.
I add some pictures


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Hi,welcome, Norway in around have lots of IMF lover''s ,many of you own multiple pair's and are proud owner. Lots of IMF supporters , IMF made so many model's to satisfy many of us.
 
Yvan_donald said:
Which one do you prefer, mk7?
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The the TLS80-2 and rspm mk4 is quite similar, in my ears. The TLS80-2s that i have is completly rewired with pure silver wires so it sound a tad brighter/clearer than the rspm mk4.
The mk7 is just in a another league. If we talk about reproducing the sound of instruments its the best i ever heard so far in my life. The snap on the drums, paino, flutes, ORGAN music, woman vocals, they are even quite good at rock music.
The tweeters is not sticking out, the mid is not colouring the sound, and the bass is quite dry and accurate.
I would say that they are far up there, even today.
 
Yvan_donald said:
In your neighbour hood, how did get to know about IMF speaker's,,from a young age, here not so many knows the brand
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I did hear a pair of IMF RSPM mk7, at a friend of me in the neighbour. I loved the sound.
Then i bought the TLS80-2
Later a pair of RSPM mk4 came for sale, i bought them
A year after that a pair of RSPM mk7 came for sale, quite high priced, but i bought them anyway.
And now a week ago i bought the CM2 just for fun :)
 
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