Hi. Look what I got yesterday, a near mint pair of IMF Compact Monitor II, with transmission line bass reflex alignment. IMF monitors were well regarded in their time but are very rare in North America, being never distributed here.
I bought them from a guy in Montreal last evening for 100$. Very good price really for such nice speakers. IMF always had great cabinet, covered with real wood veneer. IMF was known for using transmission line for bass alignment (aka PMC). See the original manufacturer site still available:
http://www.imf-electronics.com/Home/imf/speaker-range/compacts/compact-monitor-ii
This particular pair has a nice story. This guy's friend gave him the speakers a few years back. He had found them in the house locker that i had just bought at the time from an old English couple that moved back to UK.
It thought they were just junk, knowing nothing about the IMF brand name. The guy that sold them used them for years and enjoyed them a lot. He just upgraded his system with a nice pair of Focal speakers. He said that he'll kind of miss the smaller IMF. They play very nice music, with a lot of details, and presence so spooky so time that I can hear stuff I never though were there. I'm glad they found a new home where they will be care.
You can see them in my garage, on test last night with my latest amp acquisition the SimAudio W-5, making great music driven by my little Pono Player with Hi-res file. Overkill I know
I bought them for one of my sons, but I may keep them for now I may finally have nice pair of speakers for a tube SET amp, or my upcoming FirstWatt F5 and CSX1 amps.
I bought them from a guy in Montreal last evening for 100$. Very good price really for such nice speakers. IMF always had great cabinet, covered with real wood veneer. IMF was known for using transmission line for bass alignment (aka PMC). See the original manufacturer site still available:
http://www.imf-electronics.com/Home/imf/speaker-range/compacts/compact-monitor-ii
This particular pair has a nice story. This guy's friend gave him the speakers a few years back. He had found them in the house locker that i had just bought at the time from an old English couple that moved back to UK.
It thought they were just junk, knowing nothing about the IMF brand name. The guy that sold them used them for years and enjoyed them a lot. He just upgraded his system with a nice pair of Focal speakers. He said that he'll kind of miss the smaller IMF. They play very nice music, with a lot of details, and presence so spooky so time that I can hear stuff I never though were there. I'm glad they found a new home where they will be care.
You can see them in my garage, on test last night with my latest amp acquisition the SimAudio W-5, making great music driven by my little Pono Player with Hi-res file. Overkill I know
I bought them for one of my sons, but I may keep them for now
I may finally have nice pair of speakers for a tube SET amp, or my upcoming FirstWatt F5 and CSX1 amps.Attachments
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That is a good score.
They were. We sold these new in the late 70s, obtained thru Canadian distribution. Bud Fried was a US distrib.
Tweeters were bought from driver manufacturers. Looks like Audax in yours.
dave
They certainly sign with this amp.
From Recording.org, MKruger post, a little of IMF history:
IMF stands for "Irving M. Fried", after the guy who designed and the speakers. His nickname was “Bud”. IMF Electronics went out of business in the late 80's. TDL was the successor company of IMF and run by most of the same people. TDL also eventually went under. There is a new company called "IMF Audio" that bought the name, but the speakers are nothing of the sort. Bud Fried was one of the greatest speaker designers who ever lived; he died a few years ago.
The speakers you saw were manufactured between 1977 and 1983. All of IMF designs were based on the "transmission line" theory. Very different from bass reflex or any other designs you might see today. The basic principal is to use smaller drivers for accuracy and space with engineered cabinets to gain frequency response with higher levels. Many of the designs also incorporate phase shifting switches on the crossovers. The transmission line theory has never been fully developed because it’s so complex. IMF and TDL probably had the best designs.
IMF’s are hard to find vintage speakers. Do you know if you saw the "ALS40" or "ALS40II Studio"? They look the same but are radically different. ALS40’s are a compact smaller breed of IMF's, but great for near field monitoring. The ALS40’s are more abundant on the used market then some other better models. They used an 8" bextrene bass unit, 8" bextrene sub-bass unit, 4" rolled surround impregnated cone mid-range with domed tweeter. The dome tweeter was probably made by Coles. Cabinets were generally very high quality. I think part of the reason they went out of business is because the speakers where made without cost in mind.
I use a pair of IMF “Studio Monitors”, they are one of a kind. If anyone is still using them today, like me, I would venture a guess that they have had new crossovers custom made. The originals were good at the time but new ones can make those speakers sound unbelievably good. A funny thing is that Bud didn’t think the quality of wiring was an important factor in acoustics, he actually said that. Bottom line is that their great.
IMF stands for "Irving M. Fried", after the guy who designed and the speakers. His nickname was “Bud”. IMF Electronics went out of business in the late 80's. TDL was the successor company of IMF and run by most of the same people. TDL also eventually went under. There is a new company called "IMF Audio" that bought the name, but the speakers are nothing of the sort. Bud Fried was one of the greatest speaker designers who ever lived; he died a few years ago.
The speakers you saw were manufactured between 1977 and 1983. All of IMF designs were based on the "transmission line" theory. Very different from bass reflex or any other designs you might see today. The basic principal is to use smaller drivers for accuracy and space with engineered cabinets to gain frequency response with higher levels. Many of the designs also incorporate phase shifting switches on the crossovers. The transmission line theory has never been fully developed because it’s so complex. IMF and TDL probably had the best designs.
IMF’s are hard to find vintage speakers. Do you know if you saw the "ALS40" or "ALS40II Studio"? They look the same but are radically different. ALS40’s are a compact smaller breed of IMF's, but great for near field monitoring. The ALS40’s are more abundant on the used market then some other better models. They used an 8" bextrene bass unit, 8" bextrene sub-bass unit, 4" rolled surround impregnated cone mid-range with domed tweeter. The dome tweeter was probably made by Coles. Cabinets were generally very high quality. I think part of the reason they went out of business is because the speakers where made without cost in mind.
I use a pair of IMF “Studio Monitors”, they are one of a kind. If anyone is still using them today, like me, I would venture a guess that they have had new crossovers custom made. The originals were good at the time but new ones can make those speakers sound unbelievably good. A funny thing is that Bud didn’t think the quality of wiring was an important factor in acoustics, he actually said that. Bottom line is that their great.
Hi,
FWIW I can't place the tweeters, other than saying they are not Audax.
I can't place the bassmid units either, to anything typical at the time.
Also FWIW there is nothing TL about this pair of speakers, given the
cabinet and driver size, and the claimed "resistive reflex" loading.
I'd say they are a variant on aperoidic, most likely, but not certain.
rgds, sreten.
As for Bud Fried being a great designer, he could certainly talk the talk.
Which avoids a lot of hard engineering developing great loudspeakers.
MJK has interesting insights into BF's designs and they are not very
complementary, basically that the theory is incorrect conjecture.
FWIW I can't place the tweeters, other than saying they are not Audax.
I can't place the bassmid units either, to anything typical at the time.
Also FWIW there is nothing TL about this pair of speakers, given the
cabinet and driver size, and the claimed "resistive reflex" loading.
I'd say they are a variant on aperoidic, most likely, but not certain.
rgds, sreten.
As for Bud Fried being a great designer, he could certainly talk the talk.
Which avoids a lot of hard engineering developing great loudspeakers.
MJK has interesting insights into BF's designs and they are not very
complementary, basically that the theory is incorrect conjecture.
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I guest that as a lot of vintages speakers of the time they were voiced by hear, not using Advanced CAD software and measuring test Equipment. His designs could seem wrong by today findings. They were not my words, just a quote. I agreed that this particular model seems too small for a real TL.
That being said it is the soup that matter, not the can. For the price I paid they are still very nice sounding speakers, well built and fun to listen to. That enough for me and certainly way better than most of the scraps they sell in the big surfaces
The tweetters are stamped IMF. Maybe they had them made for IMF. I quick picture search on Google with 'Audax Vintage tweeter' returns me 'Vintage Audax HD 12 X 9 D 25 Dome tweeter'. The picture matches this speaker tweeter.
That was almost 40-50 years ago. Who knows...
That being said it is the soup that matter, not the can. For the price I paid they are still very nice sounding speakers, well built and fun to listen to. That enough for me and certainly way better than most of the scraps they sell in the big surfaces
The tweetters are stamped IMF. Maybe they had them made for IMF. I quick picture search on Google with 'Audax Vintage tweeter' returns me 'Vintage Audax HD 12 X 9 D 25 Dome tweeter'. The picture matches this speaker tweeter.
That was almost 40-50 years ago. Who knows...
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The name came from Bud, but he had little to nothing to do with the design work. That was done by John Wright.
dave
They were a nominally vented box with the vent stuffed with foam... yes a variation on an aperiodic box.
dave
Thats my recollection too. Fried wasn't a designer but was a first class pitch artist. His early newsletters were way ahead of their time in audiophile hyperbole.
David
p.s. I had a pair of ALS40 and they were nice enough. The mids kept coming apart as the cone edge wouldn't stick to the frame (plasticizer migration). I could never get a proper replacement for one of the woofers. Also, calling the design an "active line" was a great stretch.
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Hi,
The tweeters are not Audax, that I'm pretty sure of.
The claimed visual matches are not close enough.
As to the vent, if it phase inverts its resistive reflex,
(i.e. at resonance its still in phase with the driver),
if it doesn't then its aperoidic, its impossible to say
IMO reliably on inspection which of the case it is.
But my money is on aperoidic.
rgds, sreten.
The tweeters are not Audax, that I'm pretty sure of.
The claimed visual matches are not close enough.
As to the vent, if it phase inverts its resistive reflex,
(i.e. at resonance its still in phase with the driver),
if it doesn't then its aperoidic, its impossible to say
IMO reliably on inspection which of the case it is.
But my money is on aperoidic.
rgds, sreten.
The drivers are Elac, that is for sure. The bass/mid may be an Audax, but I think that too is also an Elac driver.
Later on in IMFs timeline, in the early 80s IMF and Elac formed a joint company called TDL and manufactured customized drive units for IMF speakers. This is why you see the IMF RSPM Mk VII with drivers that look similar to the Kef/Celestion counterparts they replaced, but are not them. Same with the Audax tweeters, they look like them but just aren't. You are right in thinking they are not Audax. Taking one out and looking at the magnet will tell you all you need to know.
Nice speakers by the way. I'm a huge IMF fan, I own RSPM Mk IVs and love them. I have had TLS 50 IIs and TLS 80 IIs, all very good. I'm sure you will enjoy yours as you already are. A recap would be a worthy idea if they haven't been already.
Later on in IMFs timeline, in the early 80s IMF and Elac formed a joint company called TDL and manufactured customized drive units for IMF speakers. This is why you see the IMF RSPM Mk VII with drivers that look similar to the Kef/Celestion counterparts they replaced, but are not them. Same with the Audax tweeters, they look like them but just aren't. You are right in thinking they are not Audax. Taking one out and looking at the magnet will tell you all you need to know.
Nice speakers by the way. I'm a huge IMF fan, I own RSPM Mk IVs and love them. I have had TLS 50 IIs and TLS 80 IIs, all very good. I'm sure you will enjoy yours as you already are. A recap would be a worthy idea if they haven't been already.
I'm afraid you have your history mixed up. Although it is a little cloudy it is well known that the IMF speakers were NOT designed by Bud Fried. He was the US distributor for the line and named them after himself before the designers had even decided to go into production. There was an eventual rift between Bud Fried and the owners and designers of IMF speakers which lead to Bud coming up with his own speakers under the Fried brand and IMF Electronics being renamed TDL. The Fried speakers were quite different from the IMF models. You can read more here:
IMF people - IMF electronics
IMF people - IMF electronics
That is the most info on the IMF drivers I could find:
http://www.falconacoustics.co.uk/downloads/Elacimftdl.pdf
http://www.falconacoustics.co.uk/downloads/Elacimftdl.pdf
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