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IMF owners thread!

tmarx said:
I sent a third email to Gerry this morning at the same time I posted here. Shortly afterwards Gerry replied to the first email I sent him 2 weeks ago.

Hopefully he'll be able to supply me with caps for the KEF 105.4's I just picked up. I think I'm going to grab some caps for my IMF ALS-40II's while I'm at it, as installing big polypropylene caps has proven to be a huge PITA.
Click to expand...

Nice grab!

I would suggest the Alcaps of course.. especially considering my latest experience involving using polypropylene capacitors on a pair of Celestion 66s. Not good results at all - I'm going back to electrolytics.
 
Just a quick note to all, with IMF speakers, the driver baffles are sometimes removable. You may want to take the baffles off and renew any seals that are there to properly seal the transmission line path so that no air leaks occur. Also, double check the seals around all drivers so they don't leak either. Adhesive draft sealing foam is commonly used, but purpose seals are available from Parts Express and Orange County Speaker among others.

Good cleaning of all switches or perspective controls, as well as retouching of solder joints, even if not recapping can pay dividends in clean new solder joints with reduced oxidation. Some may even rewire all connections.

With later large IMFs, the KEF B110 or similar IMF plastic midrange with rubber surrounds should be decently intact, but there are rubber surround refurbishing kits available from Euro eBay sources for the KEf's. If using the smaller ELAC sourced 4" midranges, all of them will have stiffened, bubbled, or perished midrange surround and they will NOT sound correctly unless rebuilt with new surrounds, or replaced with the recommended modern Monacor midrange from Falcon that fits perfectly.
 
mech986 said:
Just a quick note to all, with IMF speakers, the driver baffles are sometimes removable. You may want to take the baffles off and renew any seals that are there to properly seal the transmission line path so that no air leaks occur. Also, double check the seals around all drivers so they don't leak either. Adhesive draft sealing foam is commonly used, but purpose seals are available from Parts Express and Orange County Speaker among others.

Good cleaning of all switches or perspective controls, as well as retouching of solder joints, even if not recapping can pay dividends in clean new solder joints with reduced oxidation. Some may even rewire all connections.

With later large IMFs, the KEF B110 or similar IMF plastic midrange with rubber surrounds should be decently intact, but there are rubber surround refurbishing kits available from Euro eBay sources for the KEf's. If using the smaller ELAC sourced 4" midranges, all of them will have stiffened, bubbled, or perished midrange surround and they will NOT sound correctly unless rebuilt with new surrounds, or replaced with the recommended modern Monacor midrange from Falcon that fits perfectly.
Click to expand...

Good advice Bart.

I should add that as for the seals, I have yet to find one that has deteriorated - there are no leaks on my RSPMs thankfully. I would be wary of prying the front baffle off as you do risk the seal coming undone and may be unnecessary. I think if you can't hear or feel an air leak around the baffle/drivers, I wouldn't bother trying to take the front baffle off.
 
This should be fun...

So I just received a Mk. 168 one button tester (literally tests any component with one click and attachment to the leads) and tested all my original IMF caps. You guys might be interested in the results...the ESR results are especially interesting:

Blue Tosins Below
100uf measured 109.3uf with .12 ESR
100uf measured 107.9uf with .17 ESR
60uf measured 64.3uf with .14 ESR
60uf measured 65.38uf with .17 ESR
30uf measured 33.70uf with .23 ESR
30uf measured 33.89uf with .22 ESR
Black Elcaps Below
12uf measured 15.44uf with 1.1 ESR
12uf measured 15.48uf with 2.1 ESR
4uf measured 4.7uf with 3.7 ESR
4uf measured 4.82uf with 2.7 ESR
4uf measured 4.75uf with 1.6 ESR
4uf measured 4.57 with 4.7 ESR
Blue Alcaps Below
6uf measured 6.62uf with .72 ESR
6uf measured 6.72uf with 2.5 ESR
Blue Mylar
2.2uf measured 2.36uf with .14 ESR
2.2 uf measured 2.072uf with .11 ESR
2.2 uf measured 2.097uf with .13 ESR
2.2uf measured 2.326uf with .11 ESR
Brown Mylar
1uf measured .964uf with .19 ESR
1uf measured .948uf with .18 ESR
1uf measured .974uf with .22 ESR
1uf measured .946uf with .21 ESR

The mylars were all in good shape with relatively consistant low ESR. The alcaps and elcaps were all over the place ESR-wise.

Random Others:
Massive metal callins 120uf: 128.4uf .08 ESR
Blue massive metal 600uf maybe from my AR9LSI's: 626uf .12 ESR
Big red metal 30uf maybe from my AR9LSI's: 42.16uf .09 ESR
3.3uf mylar from B&W DM6: 3.1uf .11 ESR
12uf mylar...maybe from Polk RTA12's: 12.03uf .07 ESR
Solen 5.1uf polypropylene cap from DQ-20's: 5.073uf .05 ESR
TI D battery sized silver metal 150uf cap: 170.7uf .09 ESR
TI 12.5 MFD cap: 13.97uf .23 ESR

Just having fun measuring things and seeing just how off they are.
 
I ordered caps about a week ago, and got shipping conformation today. I did get an acknowledgement of the order, the day after I placed the order.
 
Help please !

Need help please for technical spec sheet data to gather for posting on another AK thread - "KEF Concerto vs IMF Super Compact" which is a SONIC showdown of KEF Concerto - KefKit3 - IMF Super Compact - IMF Compact Monitor III. Need the exact model and type #'s on manufacturers' parts for only TWO speaker systems - all the drivers - woofers-mids-tweeters and the crossover units .. for these TWO speaker systems = IMF Super Compact version I and Mark II version, and also IMF Compact Monitor III and IIIa speakers.
Realize some #'s may have changed in a supplied driver during certain production years of that speaker - if so for either speaker - please note years' run for those drivers & crossovers, please. Many thanks, greatly appreciate the help. Summation needed :
IMF Super Compact version I and version Mark II: need manufacturer, model & type # for-
woofer
mid
tweeter
crossover
and any of those #'s changes during years' production either version.
AND
IMF Compact Monitor III and IIIa: need manufacturer, model & type # for-
woofer
mid
tweeter
crossover
and any of those #'s changes during years' production either version.
Kindest regards.
 
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Found very much info on these drivers' specifics.

These drivers were made by mfrs - Elac, Peerless, Kef, Audax, Dalesford, IMF branded in-house custom-built and EMI.

IMF Super Compact early version I mids Elac 4EM/101, or possibly some were EMI.
IMF Super compact early version I tweeters IMF-branded reworked Peerless DT 10 HFC soft dome.
IMF Super Compact early version I woofers IMF-branded KEF B200 (large magnet version).

IMF Super Compact later Mark II version mids Elac 4/200 bextrene cones.
IMF Super Compact later Mark II version tweeters Audax HD 12 X 8 D 25 SP.
IMF Super Compact later Mark II version woofers IMF-branded Dalesford 8/22 SP1014 bextrene cone.

IMF Compact Monitor III (? or IIIa ?) mids Elac 4/200.
IMF Compact Monitor III (? or IIIa ?) tweeters Audax HD 12 X 8 (or X 9) D 25 SP, or IMF-branded TW1500 = a rework of Peerless DT 10 HFC.
IMF Compact Monitor III (? or IIIa ?) woofers either IMF-branded KEF B200, or Dalesford or IMF-branded Elac.

Curious - what made Compact Monitor IIIa change from III ? Does anyone know ? Maybe different drivers/crossovers contributed to the change in version.

Not sure how accurate ALL this info is - came from many credible sources, but very much is accurate.

IMF Super Compact version I made 1973 to 1980 and version Mark II made 1979 to 1985.
IMF Compact Monitor III made 1980 to 1986, BUT NEED years made for version IIIa.

ALSO NEED crossovers model#/type# in the TWO speaker (SC-I, II and CM III, IIIa) systems for all versions - confident these were all IMF-branded in-house built crossovers.

Maybe this info can help some others.
 
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Found more info -

IMF Compact Monitor III version is a ported cabinet. (1980-1986)
IMF Compact Monitor IIIa version is a closed cabinet. (1981-1987)
 
Hi. I just got a near mint pair of IMF Compact Monitor 2 yesterday ;) I wonder if someone has the crossover diagram for those?
I got them from Vinyl Fan from this thread page 1...
 

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My first post here, I dabbled in the Yahoo account but don't really get on with that format.

Last night I read all 39 pages and was surprised to see the CM2 being mentioned (on the last page). I have 2 pairs of CM2a's (closed cabinet)and a pair of ALS30's. A friend of mine has a pair of TLS80's but of all of them I prefer the sound of the CM2a's.

I bought them cash from IMF in High Wycombe as my father knew them personally. I think they were the proto types. When I spoke to them they said don't be fooled into thinking that just because they only have two speakers they are not as good its just easier to get a good sound with more drivers.

I find the CM2a's considerably brighter with a more punchy bass and louder. The ALS30's sounded similar to the TLS80's which have a more rounded sound-a bit more mid, less treble and although a deeper bass its not so tight.

Personally I prefer the CM2a's especially when the size is taken into account. I'm also surprised, considering they have the same audax tweeter, they sound so different in the top end. As I've had them from new I would say there's nothing wrong, its just the way they were made. Its been mentioned earlier that there's something missing from the top end in the TLS's so may be there's something to learn here?
 
meadowhog said:
My first post here, I dabbled in the Yahoo account but don't really get on with that format.

Last night I read all 39 pages and was surprised to see the CM2 being mentioned (on the last page). I have 2 pairs of CM2a's (closed cabinet)and a pair of ALS30's. A friend of mine has a pair of TLS80's but of all of them I prefer the sound of the CM2a's.

I bought them cash from IMF in High Wycombe as my father knew them personally. I think they were the proto types. When I spoke to them they said don't be fooled into thinking that just because they only have two speakers they are not as good its just easier to get a good sound with more drivers.

I find the CM2a's considerably brighter with a more punchy bass and louder. The ALS30's sounded similar to the TLS80's which have a more rounded sound-a bit more mid, less treble and although a deeper bass its not so tight.

Personally I prefer the CM2a's especially when the size is taken into account. I'm also surprised, considering they have the same audax tweeter, they sound so different in the top end. As I've had them from new I would say there's nothing wrong, its just the way they were made. Its been mentioned earlier that there's something missing from the top end in the TLS's so may be there's something to learn here?
Click to expand...

Hey there,

Welcome!

I've not had any experience myself with the CM2a or any of the Compact Monitors, so I can't comment on that. But it's nice to see that you have some history with the brand. If you've got any cool stories feel free to share :)

As for the tweeters on the TLS series, it's more to do with the original Audax tweeters on the TLS 50, ALS40/30, the Super Compact, and whatever other models utilized the Audax 12x8 tweeter. They put a coating over the dome and over the years this dries out, which lowers the SPL output of the tweeter and affects the frequency response. As a result, these speakers today will have a diminished HF response. I have yet to figure out what sort of coating you could apply to the dome to revitalize their response, but I am sure there is a solution somewhere.

I think the model you have, the CM2a, does not use an Audax, but rather an Elac equivalent and as far as I know these tweeters do not suffer from the same issue. These are definitely a different sounding IMF, because they are a later production model with the Elac drive units and not the Kef/Audax/Celestion drivers you see in the early IMF models. Like I mentioned though I've yet to come into contact with one of the later models so I have no comments about my findings on the differences between the later and earlier units.

Again welcome! It's nice to have another IMF owner onboard. :thmbsp:
 
I bought them when I was 15 which was in 1981. My understanding was they went bust due to life long guarantees but that may not be true. I have however replaced every tweeter.

I'm glad you mentioned the Elac tweeter as I found it better than the Audax. It had a better range, higher and lower and did ask on the yahoo site what it was but I guess most of these sites are dedicated to the bigger stuff. My CM2a now have the Audax tweeters which the ALS30 have and definitely do sound better in the two way speaker. I tried to find out what the Elac tweeters were 20 years ago but couldn't so I ended up with both Audax and Peerless which in my opinion do not sound as good but that may be because of the crossover etc. It's not because of them drying out as they sounded like that from new. I will restart my hunt for those Elac replacements.

Unfortunately I don't have any great stories about IMF but I'm glad I lived in High Wycombe and had that personal contact with them. I would have lived in audio ignorance if I hadn't . My set up still knocks spots off all my friends new B&W, mordant etc etc. The only thing of interest is I was the last person to see David Martin of Martin Audio alive.

If anything us 'lower end' small IMF speaker lovers have a bit more of voice for help and upgrades etc. These small gems are easily lost in the myriad of mass produced similar sized speakers.

Thanks for the warm welcome. Si.
 
Here's some info some may be wondering about concerning coatings on drivers for IMF loudspeakers. This doesn't pertain to tweeter-coating, but it is about the KEF B110 midrange driver coating on the cone -front, and also sometimes rear of cone too. The B110 was used in a few IMF designs.

From a 2008 Pinkfish forum thread titled IMF Professional Monitor IV, Paul, id PulseStudio writes to Jerry B of Falcon Acoustics UK about the doping mixture applied to the cone. The original material used was called "Plastiflex". As of 2008, the closest thing to it is the expensive German C37 lacquer. This has to be mixed in a lacquer ratio to the dope that was known, but that exact ratio is hard to find -it is around somewhere if someone kept archives.

Suggested to approach the original consistency and mixture is to start mixing trial and error until reaching a dried result close to an old original cone as a standard. Mix ratio of 4 parts PVA to 1 part dope (4/1) is a starting point recommended in the thread. The stuff other than the PVA is said to be available in hobby shops that sell model replica airplane gliders, and stuff is - what's used for "...stiffening tissue paper on model gliders...".
So, it reads as a 4 part PVA/1 part dope trial ratio. At least it's a starting point to dope mid drivers, and trial & error with the weaker ratio first, or increasing to more concentrated ratios was recommended.

Most important they said too, was not to experiment on your good driver cones - but to paint your formula onto some other similar substrate, like a black paper card, for all testing ratios. When dry -compare to an old factory-doped cone for similarity -when happy after finding a close result, then apply to good driver cone ! Some say it really is up to experiment & will change the sound on how many coats applied. Noted was KEF themselves changed the formula, mix and coating over several years - so a absolute standard is hard to find, unless all the data for those years is uncovered.

There are most likely a couple of folks that have done this already here on AK and have good experience on what finally worked best for them. The drivers were common on IMF, Fried, and many other manufacturers KEF supplied. Have heard some doped thin, others heavy. A suggestion is apply a coat, dry, install driver, listen for sonic-signature desired, and repeat process until happy with sound.

Hope this may be of some help for those wondering how they can get close to the original doping of the midrange drivers from the factory.
 
What do you all think about Quad and IMF, specifically a Quad 405 with a 34 Preamp, both older version 1. The review I read in Stereophile on the 405 did not impress me but the tilt control of the 34 and it's gearing towards Classical does.
 
Not much experience in Quad specifics, but can say - Quad and IMF were commonly matched in eastern mid-atlantic USA back in the day when new IMF was sold. I heard this combo many times and can attest to a good match.

At that time, the matches that worked well for IMF that I heard were Quad, GAS Thaedra with either Ampzilla or Son Of Ampzilla (sensational). They were all excellent. Quad combo was 33/303 - preamp/amp. I heard every genre of music thru these matches & know the 2 GAS Bongiorno amps mentioned with their branded preamps (especially Thaedra) handled every genre very well. The gear I heard was between 1973 to 1985. Quad also made the 44 and 34 preamps and 405 amp in those years.

The hifi shop that showroomed this gear had access to every brand -it was their part-time hobby of 2 owners that had other great careers. They poured their souls into trying every piece of gear they could find that was noteworthy, then after testing, only sold what was found to be best. They just needed to break even, as both did very well with full time careers and the hifi shop was just for fun & passion. So, I remember them going thru tons of great brands but only matching up and ultimately selling the most synergistic combinations.

IMF, GAS & Quad were notably the best gear in the shop matched together. I have the GAS Son Of Ampzilla with Thaedra for RSPM Mk IV, the match I found best for my liking. Quad is exceptional gear, and I really liked it with IMF also; both Quad or GAS with IMF is a great match, based on model #'s I heard. Either brand was divided among personal preference with folks.
Possibly of some help.
 
Yeah, the Quad + IMF combo is a good one.

I don't know about the Series I 405, I do know the Series II is better. But, luvmusik is on the money, they were commonly matched and sold together. It's a good pairing.
 
Thanks Luvmusik, this is a tricky one for sure. A complete set is near me, thinking, always wanted to try QUAD. I might just wait though and go for a version 2. But what made me ask the question is the lack of impact on the bass that Gordon Holt refers too in his short opinion of the 405, and that amps/receivers that have loudness defeat (i.e. loudness on by default) I tend to turn it off with the IMF's because it sounds bloated.

Cool sounding shop too.

Overall I have yet to find a combo that i was displeased with on the IMF's, have to keep playing.
 
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