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IMF owners thread!

Yvan_donald said:
Hi the size pretty close to mine,only the height differ 42" ,caster ad 3/4"-1', 2' inches less because 39"
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Oh yes, that's right. I suspect if mine had the castors it would be about the same. Mine did previously, there's holes in the bottom where castors used to be installed. I'm going to try and source the same ones, since it would make them much easier to move around.
 
You won't find it on the net as all the IMF circuitry is rather well guarded. Jerry in the UK will have it but will ask that you don't post it up on the net.
 
I'm not promising but I may still have some pictures of the late PM3 crossovers. I had a pair of these in Formica finish and I had to rebuild the crossovers.
 
Hi, the pictures of both PM3 X-over, old and improved latest model are in AK IMF threads page 32, but I remember I have seen some pictures of MK3 X -over who have different brand of components (capacitor) but with the same value.Myself I own two pairs and the are exactly the same parts.But the second pair have some corner damage,but it's a future project to make a new one with some improvement,and probably veneer on top of he formica and inside presswood of the TL put veneer too+ veneer the baffle.
 
No problem. They are on another hard drive and that saves me the job of searching.

As an aside I didn't mind the Formica finish. I believe it was also some form of panel damping or something like that. I also think the PM3 sounds better on stands like the TLS80 etc.
 
Hi, with the right pre-amp and an amp with good damping factor the bass sound very natural and not bony,never try to raise them up but they are tall,maybe tilt a bit back 5° will give another dimension to the sound
,to me they sound great with wide image already.
 
I finished recapping my RSPM MKIV - Alcaps and Clarity caps - interestingly the new Alcaps made less of a difference than in the TLS80s - but the bypass cap to the 60uF electrolyte was clearly audible (always to my ears and YMMV). Also the new film caps sound different to their implementation in the "smaller" speaker. Be that as it may - the RSPM are most wonderful indeed and they make me listen to a lot of music that I found sonically difficult before (thinking here mostly of chamber music). But as they are so incredibly balanced and natural sounding, even recordings that sounded harsh or lifeless before are now something else. This combination of clarity and naturalness I find positively unique - it's a combination that I had been looking for for a very long time indeed - marvelous stuff!
BTW: I am now using my moddified TPA3255 Class-d amp and it suits those speakers very well.
 
A small update - I have ordered a pair of the Falcon FB110 drivers. Though the B110s are functional, I recall speaking to Jerry Bloomfield some time ago and he recommended replacing them anyhow as the old drivers are a fair ways out of spec now, based on his experience of measuring several pairs of used old stock B110s. I'll be sure to report my findings once they arrive.
 
Hi, Jeff (canucka), it have for sure got be relate to IMF owner who push their speakers a bit too much, to me the B110 never move (praticly no motion),so the rubber surround doesn't look to have sagging problem or change FS. You will have to recoat the new cone speaker. Do you know if It's still made with bextrene or the new material like Kef 107,the center dome (flat?)
invert surround rubber?
 
Yvan_donald said:
Hi, Jeff (canucka), it have for sure got be relate to IMF owner who push their speakers a bit too much, to me the B110 never move (praticly no motion),so the rubber surround doesn't look to have sagging problem or change FS. You will have to recoat the new cone speaker. Do you know if It's still made with bextrene or the new material like Kef 107,the center dome (flat?)
invert surround rubber?
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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.
 
Hi, because of the b139 sp1044 or sp6171 use the same repair kit,don't the new Falcon b139 coil ,can be install on the old frame? Magnet is the same. Coil diam.2".
 
I suppose those are viable options, but without any T/S parameters, it's challenging to say if they'll properly integrate with the existing crossover. They may have differences in the magnet strength or overall response that might make it so the crossover has to be modified. Other issues could arise such as sensitivity, etc. With drivers it's not wise to simply replace one with another, even if they may appear to be quite similar, since there are a lot of factors at play.

For the B139 they don't sell the new coil, and really the main reason to replace it is because of the suspension (spider, cone, etc.). Bass drivers suffer the most from age-related issues, so I would only be interested in replacing the entire thing as opposed to just the coil. For the record, all the drivers in my IMFs are functional, this is simply to refresh them. If I can figure out a way to fit the SP1044 frame in the older PM cabinets, I'm going to replace them.
 
Hi,but you know Jeff, the old kit for the b139 was coming with everything ,complete parts coil,spider,cone and rubber surround. Ask Jerry if they can fit in an old frame?
 
Yvan_donald said:
Hi,but you know Jeff, the old kit for the b139 was coming with everything ,complete parts coil,spider,cone and rubber surround. Ask Jerry if they can fit in an old frame?
Click to expand...

Oh you're talking about transplanting the new B139 into the old frame. Hmm, that seems difficult, I suppose I could ask about that.
 
I have recently found a nice pair of ALS40-IIa, and am looking at what needs to be done to bring it in perfect condition.
The foam edges of the midranges are not bad, just a little crusty but no holes or cracks yet, so I will leave that for now.
Crossover is a different matter. From what I have read, all condensors of this age suffer from aging, and the speaker will benefit from an upgrade.
I have contacted Falcon, but they have no kit for the 40-IIa. So my best bet is to open it up, make a list of the values, and order that.

Does anyone here have any experience upgrading the 40-IIa? (difference from the 40-II is easy to spot: the a has Bextrene "spokes" on both woofers)
What should I expect in sound improvement?
Ideally, does anyone already have a list of condensor values?
 
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