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IMF Professional Monitor IV

The mid driver used in the Super Compact II's were Peerless KO40-MRF, a 4" Mid doped paper cone unit now obsolete, but you may be lucky and find a pair on the Bay, failing that then Morel do a suitable replacement in the form of the EM428, I had always thought that Monocor made a 100mm ( 4" ) mid replacement driver but it appears not, only the B110 replacement 135mm driver, hmmmm !!
 
Thanks Pulse, Belgium isn't awash with IMFs ,and I flat refuse to use greed-bay so maybe I'll take the Morel option. Or just wait it out. Good things come to he who waits (or is prepared to skulk around junk shops & boot sales for weeks on end);)
 
I recently acquired a flawless pair of IMF RSPM 1V on ebay. Got lucky I suppose. Originally I purchased them for my in-laws but now, having heard the TL sound again after 34 years, I can't let them go. I also own a pair of Tannoy Westminster Royals which I will likely keep for a while. A card carrying member of the SET Party, I was shocked discover the difference power makes not only for the IMF's but also the Tannoys. Not quite as voluptuous in the mids and highs but ever so much more exciting (esp on my beloved organ music!). I learned this doing a side-by-side using a '70's Marantz receiver (2285). Now thinking of moving over to the 'dark side' of SS and wanted some recommendations from the brain trust. At present I want to keep using my tube line stage so it is an amp I am looking for.

Opinions I have gathered so far include: vintage '70 & '80's McIntosh (eg. MC7270), Quad 405-2 (although users comment on a hiss that has me concerned) or the 606 which I have read about on Pink Fish, or possibly the new NAD Masters Series integrated (Yes, I would have to retire my line stage but NAD is known for high current high damping designs which I have learned is especially impt. for the IMF's). I would not want to spend more than CAD$2500. I suppose I could keep the Marantz and unload the line stage and my MAC MR78 tuner and be done with it. At any rate, whatever I end up with, the goal would be to optimize both the Westminsters and the IMF's as I may keep both. Any advice would be greatly appreciated.

Finally, since I am keeping the IMF's, my in-laws who were smitten with the sound want their own pair. Who can blame them. However a more compact model would suit them better (TLS 50 or 80-2 for example). Any leads would be appreciated. I live in the Toronto area. Many thanks.
 
Beertenor, I think that you need an Avondale pair of M130's to drive the RSPM, or equally something with a massive damping factor and huge current reserve. David ( DSJR ) will also recommend the Crown amps, which do offer a good damping factor as too did some of the earlier HK amps, I always admired their build quality in the 80's for the use of overly large power supplies, seems everyone is on the bandwagon now.
Dave will probably chime in and advise the model of his Crown amp, the RSPM being a quarter wavelength TL design must have a good clean high power, high current reserve, SS amp to get the best from them, but the Avondale list of amps I highly recommend, and no I do not have any allegance with les or Avondale, just recognise a good product when I hear it, and have built a few with differing size and configered supplies and they all sounded really top drawer, and he offers a superb SOR try before you buy deal, so how could you go wrong, on your speakers in your own home, worth a listen I would suggest.
Paul
 
Ding-Dong!! - Well, you said "Chime in :D"


Crown amps tend to be a bit "light-n-bright," especially the bigger and newer ones. perfect for the Mk 3 series of IMF's. The bridged D-60's I use have a less assertive brightness about them, compared to the D150A/DC300A of the period.

MC2 do some awsome looking power houses that don't cost a fortune and these may be a proper modern replacement.

The MK IV's (and TLS80 II's) have a drier bass compared to the earlier models as I remember, but when new, could have a sting up top, which may have gone thirty plus years later. I'd suggest a Quad 606 (used with earlier IMF's the bass may possibly wallow), the AVI Mono's (any of them of any age) as they have good damping and no character of their own and, any good amp with a dry quality to the bass.

Paul (Pulse Studio) really rates his NCC200 derived amps and and if they can cope with a bassy Rogers BBC derived monitor then they should cope with mk IV's easily :)
 
Thanks Paul and DSJR. Not familiar with any of the above but will now do some more homework. Many thanks. Did get a comment on the 405-2 versus 606 Quads. 405-2 is a better sounding amp, esp with Tannoys. "Best 100 watt amp available!" There ya go.
 
Here is a link to Avondales site:

http://avondaleaudio.com/high-end-audio/monoblock-power-amplifier-m130/

if you need any help call Les, he is not particularly fast to respond to mails, but is a true gent and will help all he can for whatever stage of amp you require.
You can go from basic bare PCB's and assemble the amp boards yourself if you have soldering experience, or ready assembled NCC200 boards, and put together the power supply, Les will supply everything to complete the entire amp build even a very high quality enclosure, or simply save all the time and effort and buy ready made M130's, the choice is yours as they say :)

Sorry forgot to mention, the TLS50's are lovely, lively speakers, not quite the neutral character of the pro IMF range but a very worthy 70/80's box of drivers.
Paul
 
I have a working pair of IMF RSPM Mk VII. I used to have 3 pairs!!
I was at Reading university, and there were loads of these in the hallways from a Professor Felgett who I think used to be a shareholder of IMF. They were collected by a local company who were going to install the drive units then sell them. For some reason they could not, so gave them away!!
They do sound Fabulous. I am driving them with an amplifier that was made to a design by a Professor Cherry using NDFL. They drive the IMFs very well.
I am looking for a pair of Tweeters that would be compatible with these speakers. Does anybody have any ideas on what they are or where I could get hold of some?
 
The later IMF's sounded a bit drier and leaner than the earlier ones from what I remember.

Why do you need extra tweeters sir? The ones used by IMF and TDL used to go up more than high enough as I recall..... or have they blown?

Try googling IMF and you should get the site dedicated to them. There may be some pics on there..

I've said this earlier, but the BC2's I'm using look huge in our little sitting room. I remember how tiny these were when next to some RSPM's........:D
 
Greetings from London.

My MK VIIs take up a load of space in my lounge. My wife hates them but is very patient with my quirkiness!!
When I got hold of the cabinets in the first place, I could not find the tweeters, so improvised with a cheep pair from a local store. They deserve better, so I have stared the long treck of trying to find some. I do have a pair of the original super tweeters fitted, but it's hard to tell if they are optimum when the tweeter is poor. Any help in finding a pair would be amazing. I've checked out a number of sites & links on Google.
Does any body have the full specifications for the IMF TW 1350 so I could find an equivalent?

Thanks
 
Not an answer, but how long did IMF use the Celestion HF1300's? A pair of tweeters such as in these might be just what you need...

http://imf-electronics.com/RSPM/index.html

This site also has details on the mk VII and although the tweeters are now ferro-fluid treated, the basic setup still looks like the HF1300/HF2000 combination so beloved of the era (and not bad sounding either if the crossover is set up properly)..
 
Would it be accurate to say that IPL Acoustics are the modern day equivalent of IMF in the speaker type they make? Albeit that they are in kit form.

They certainly look interesting and cheap for the diy'er

Ronnie
 
The PMC transmission lines were developed by Pete Thomas due to the fact that he loved his old IMF Professional Monitors back in the mid seventies when I believe he was still at the BBC. The MB1 (and by definition the MB2) makes a superb modern take on the idea, as long as you don't mind them being set quite high off the floor. I'd much rather have these instead of ATC 100's if a passive speaker was to be used (and ATC's active 100's are very much cheaper than a full PMC/Bryston active setup.)
 
Hi,

Just stumbled across this thread. Looking for a little advice. I currently run a pair of 12" Tannoy Lancasters. Low WAF but we both love the sound. Amps are Avondale Grad 1/ monos.

Can anyone tell me how the IMF house sound compares with the old Tannoys and whether the IMFs are designed for free space or close to wall placement.

I have had bass boom isues in the past but not with the Tannoys placed close to the rear wall.

Thanks

Kevin
 
Tassie said:
Hi,

Just stumbled across this thread. Looking for a little advice. I currently run a pair of 12" Tannoy Lancasters. Low WAF but we both love the sound. Amps are Avondale Grad 1/ monos.

Can anyone tell me how the IMF house sound compares with the old Tannoys and whether the IMFs are designed for free space or close to wall placement.

I have had bass boom isues in the past but not with the Tannoys placed close to the rear wall.

Thanks

Kevin
Click to expand...
Big IMF's are meant to be used 'free space'. Using TLS 80 MK2's for some 25 or more years, the really deep bass produced, is enormous. -and produced from inside the cabinet! The thought of placing them 'in corners or close to walls' for any form of further reinforcement would be a big, big mistake.
 
Many thanks. Sounds like my curiosity has been satisfied. My room is small so I am a bit limited. I guess I should stick with the Tannoys.

Cheers
 
Good old Tannoys tend to have a leaner bass quality limited only by their cabinet size and this, coupled with a more forward midrange, is perfect for close to wall mounting. The mk2 IMF's have far more damping in the lines and this helped in smaller rooms no end, but the older IMF TL's needed ROOM or the sub-bass would almost make you feel nauseous.. The only possible problem with any older Tannoy DC "pepperpot" type is the potentially (and certainly measurable) ragged treble, which needs a good grain-free valve style amp (or a VERY well behaved solid-state amp) to do the job - I understand Tannoy made their own badged amp for a while in the eighties.

I've said this before, but amp choice is crucial for these old Imf'S Too. The huge damping available from 1970's Crown and HH style amps being essential for proper bass control. late seventies faves such as Naim, EAR 509's and the huge US powerhouses that were coming over for the first time (Threshhold etc) just gave you too much of a good thing, although Bryston's seemed to work well (and still do with PMC, hence the marketing tie-up).
 
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