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IMF owners thread!

Yvan_donald said:
hi,the one with regular midranges under the TW,same as this call professional monitor.without the big plate at the bottom.People use to call them MK IV or MK VII relate to the RSPM.And tell me ,you or other's owner of RSPM,do they play with the adjustments control on theirs speakers or mostly everyone keep it flat?Yvan
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Yvan,
I tried all the possible combinations of RSPM Mk IV front control settings and found what worked best in my room. I run at Filter "Out", Slope "Add", and Tllt "Fall". In this room it also gives the deepest and strongest bass characterization, so care is needed to watch woofers, volume and have a high-damping amp.

With 3 controls, each having 3 settings, there are lotsa combinations to tailor for most rooms and sound preference.
Frank
 
Hi,so they really are taylormade for any situations,that is very good to know.I always think common people didn't play much with the control settings. Yvan
 
Very versatile control settings. Although the loudspeakers had their origins in the recording studios, the RSPM models are used a lot in homes for listening and the speakers excel in hifi listening to the purest sources. Not very forgiving, as poor-quality recordings will sound even worse on the RSPM than a forgiving system (ex: Fried Model R series loudseakers). There was an IMF dealer real close to my home here, back in the day they were produced, and the shop had RSPM as demo display auditioning for home use. Not sure how many sold, but they do sound good in my home.

Two things they do lack, as many studio monitors can lack, is they don't negotiate extreme dynamics very well like the best of high-end home speakers. ppppp to FFFFF, and transients are far more dramatic on other systems and quite apparent. The other thing is the RSPM cannot play very loud in a large or very large room, they are volume and power challenged comparative to high-end speakers that can fill a large room with loud or very loud volume. For most sized rooms small, medium, up to borderline large, the volume is fine and adequate for normal listening. For this reason, I have read of some running 2 pair RSPM, and to another effect, the TDL Reference Standard model (although most prefer the IMF sound & contol settings to the TDL). If real loud volume is needed, though, those are 2 good alternatives that work. Other than these 2 limitations, the speakers are really fantastic in all other ways.

IMF actually made a custom loudspeaker system for an unusually large British recording studio many years ago. The system was detailed if I recall on the pinkfish forum, were at least 2 members saw & heard the system. Each of 2 speakers contained a number of woofers, a number of midranges, a number of tweeters and a number of supertweeters. It handled an enormous amount of power -the studio's goal in purpose. The few that heard this system said not only was it extremely loud, but when they walked over a few rooms away, the transmission-line bass could still be felt reverberating the walls and floor a few rooms away. I think they only made 2 pair of that rare custom system & who knows what's become of it now. Be nice if it is not parted out & is still intact somewhere. It was very large.
 
luvmusik said:
Two things they do lack, as many studio monitors can lack, is they don't negotiate extreme dynamics very well like the best of high-end home speakers.... The other thing is the RSPM cannot play very loud in a large or very large room, they are volume and power challenged comparative to high-end speakers that can fill a large room with loud or very loud volume....
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Good points Luv-er!!! During the late 70's into the 80's Disco was king and studios were trying to mix that type of really dynamic music. It was one of the reasons that KEF made the KM1...

Check out this thread. Now there is a Studio Monitor that can drive SPL and fill a room!!!
 
It's true, probably the achilles heel of IMF loudspeakers is their inability to handle large swings in power. This is a result of the transmission line. Two issues arise from this - low sensitivity, which requires more power output to achieve respectable dBs, and also the Kef B139 can not handle large amounts of power.

It's kind of ironic because whenever I have guests over and they see how large the IMFs are, their first thought is that they must play incredible amounts of bass and also go very loud. While they do go deep (and sound great doing it), they definitely are not designed to play very loud. I believe max SPL sits around the 100dB mark, which compared to many other loudspeakers (an example is the Kef 107) is quite low.

Therefore, dynamics are not the strong point of these big IMF speakers. I think this is why IMF speakers were not used in studios all that often, at least based on what I've found. Studio monitors, big ones that is, are meant to handle lots of power and play loud without breaking down. AlthougH IMF later on had Elac commissioned to produce drive units custom made to their specifications, they still could not handle that much more power. The Elac bass driver that looks much like the B139 (the shape, not the cone of course) was designed to be an improvement over the Kef drive unit in that it had a light, stuff cone with a bigger voice coil so that it could handle more power.

One of these days I would not mind having custom built transmission lines with modern drive units. High sensitivity can be achieved with SPL IMFs can't even dream of. Can you imagine what that might be like? IMFs with better dynamics? It would be something else I think!

Of course all that said, there are lots of pros to the IMFs which is why they are so well regarded and why we all here like them. What they do, they do very well. You can't ask for everything from a loudspeaker, especially not one designed nearly 40 years ago!
 
canuckaudiog said:
Therefore, dynamics are not the strong point of these big IMF speakers. I think this is why IMF speakers were not used in studios all that often, at least based on what I've found....

Of course all that said, there are lots of pros to the IMFs which is why they are so well regarded and why we all here like them. What they do, they do very well. You can't ask for everything from a loudspeaker, especially not one designed nearly 40 years ago!
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This is a really interesting subject probably worthy of it's own thread... "Evolution of the Studio Monitor".

Obviously there are different types of studio monitors; Near Field for the Mixing Deck, Session Monitor for the Performance Room, Demonstration Monitor for the final cut. There are a number of areas that a specific type of monitor is needed in a studio.

Then you have time periods! Obviously the heyday of the IMF's was in the Early 70's. Thats when John Wright was developing the IMF's. How much penetration did they have into the London Studio's? That's a good question!!!

Obviously KEF, Rogers and Spendor had a better representation given the work they did with the BBC. But I bet there were some IMF's being used for Demonstration of the final Album Releases.

Here in the states, I would assume it was mostly JBL and Altec Lansing? Dunno... again interesting subject that you could probably write an interesting book about! Complete with "pictures" and "schematics"!!! :thmbsp:

Anyone here like to write (you know me!)? We could make it a compilation work! :scratch2:
 
That would be an interesting exercise, to find out what monitors were big in each era (60s, 70s and 80s) and in North America and Europe. Makes you wonder.

You are right about JBL and Altec Lansing, they were pretty quintessential, especially Altec Lansing where the 604 was more or less the standard. Things changed in the 80s, where the UREI 813 became the standard, but JBL was still around then. Not sure about other brands, but those are the two I am familiar with.

It's possible that IMFs were used more in Britain/Europe, which may be why my research lead me to think they weren't popular as monitors. I have read accounts of them being used as such, mostly the SACM model, so I do know they were purposed for that.
 
Hi,in this regards probably the HPCM was more intend for studio monitoring,never see one in Montreal,but who knows maybe some recording studio have some.The inductors wire gauge IMF use in their speakers is very small(like 22GA.),in the TDL it is the same?All the new brands of speakers seems to use a pretty good gauge to handle big wattage,Kef a bit bigger.Yvan
 
Yvan_donald said:
The inductors wire gauge IMF use in their speakers is very small(like 22GA.),in the TDL it is the same?All the new brands of speakers seems to use a pretty good gauge to handle big wattage,Kef a bit bigger.Yvan
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That is a good observation.

I.M.Fried used 18 gauge air core on the mid bass driver and 14 gauge air core on his subwoofers with his Fried Products line.
 
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Hi,this pair of MK III for sale on Ebay is a good example of ex owner who have no respect for the brand.What a disaster,Yvan.
 
Hi everyone,
I'm new to this forum.
I've got a pair of IMF Pro Monitor mk3.
I wonder, if I could improve the sound by buying a pair of
Tls80 mk2, or RSPM mk4 improved?
I could buy one of these above.
Which one is the best?
Regards
 
hi,welcome to the forum, own pair of MK III improved,how long do you have your's?Not shure if it will be an improvment with the TLS 80 mk2, but the RSPM yes,me I prefer my MK III,which preamp,amp do you use for driving them? Yvan
 
Hi Yvan,
Thanks for welcome:)
I've got them for about 1,5 year.
They were in very bad state when I bought them.
My friend did fantastic job and put them back to live.
We had to rebuild the crossovers boards.Same time we replaced caps.
Put nice copper wire inside. Had to replace supertwitters, put new speaker cable
connectors. He also built for me stands . Same as original.
I use Transcendent Sound Grounded Grid pre and British Albarry M608
monoblocks. I would like to get a bit tighter bass, but that could be
my room, or I may have to change the amp to achieve it.
So I sit on fence atm. Wonder, if I get much better sound with RSPM, or just
slight improvement. It's a hassle for me to get RSPM as I'm based in the UK
and would have to transport them from continent.
Maybe I should get some bass traps, or try different amp.
I would love to try them with valve amp.
I can buy big, vintage valve power amp the Beard p101.
100wpc.4 KT 88's per channel.
Too many ideas and options:)
 
I don't think the RSPM Mk IV will be a significant improvement/difference over your Pro Mk IIIs. Similar drivers, but newer versions of them. The crossover is quite a bit different. Not a night and day difference however.

Personally, I prefer the sound of the Mk IV over the Pro III - it's more neutral with less emphasis on warmth. Very nice speakers. What did you replace the super tweeters with and what capacitors did you use?
 
The super tweeters were brand new Coles units, the same as what was fitted originally except I left the faceplates on the new ones as they looked neater. I can't remember what make of caps I fitted. I'll see if I have a pic of the rebuilt crossovers somewhere.
Regarding speakers I pulled the trigger and bought them:)
Couldn't resist. Bloody audio bug:)
What amps do you suggest guys to use with RSPM mkIV Improved?
 
Hi.not to familiar with the Transcendant sound and Abarry amp, here on this side of Atlantic,like I said on previous post I drive mine with Audio research SP6b preamp with Bryston 3b-st amp (will change for the sst model later), I can't ask for better sound.PMC use Bryston to drive their speakers.Bass is tight and natural on all kind of music,but Luke usually MK III come with Celestion HF 2000 super tweeter and have caster wheel no stand?Good thing to have change the wires and speaker's post,I did the same and just this improved the sound.Yvan
 
Yvan_donald said:
. . . but Luke usually MK III come with Celestion HF 2000 super tweeter and have caster wheel no stand? . . .
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Yep that is right.. the Pro Monitor III had no stands and had the Celestion HF2000 as a super tweeter. Can you post a picture of your speakers for us?
 
We removed the castors and built metal stands exactly same
as for other IMF models.
Therefore I believe I own the only pair
of Pro Monitor with stands;)
 
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