Help me identify my vintage loudspeakers

[Tim Brooksbank]

I have acquired a wonderful pair of IMF transmission line loudspeakers but I cannot identify which model I have.

I was sold these as TLS80s but they aren't quite the same:

1. The lower frequency tweeter is not the correct part for TLS80, it looks to be the part used in TLS50.
2. The KEF B139 woofer has a label on it (inside) which suggests is too old as it pre-dates the launch of TLS80.
3. The "aspect control" present on TLS80 and all later large IMF loudspeakers is not present and clearly never has been present.
4. The front cabinet design is closer to a PM than TLS80, in particular the ports at the bottom for the transmission line are incorrect for TLS80.
5. The crossover is not a TLS80 crossover, it's a much simpler design. It doesn't appear to have ever been changed so I don't think it is a home-made substitute.
6. The IMF badge on the front grilles (not shown in photo) simply shows "IMF". By the time TLS80s were made the bade showed "IMF Electronics".
7. The cabinets are slightly the wrong size for TLS80s, the height is about correct but the depth and width are slightly different.
8. The front panel which carries the drivers is not detachable, unlike a TLS80 front panel.

Any help with identifying what I've got will be much appreciated. They sound awesome, but not knowing what they are is frustrating.

Thanks
Tim

 

[BoredSysAdmin]

have you tried posting your question on Audiokarma forums?
They expertise in vintage audio.

good luck finding out the info you're after

edit: You should probably make better (sharper) photos of your speakers - These ones looks like Instagram effect - it doesn't help us

 

[Steve81]

Hi Tim,

I can't claim to know much about IMF speakers, but one guess might be that it's one of the iterations of their Professional Monitor line. It looks like there were several revisions, and unfortunately pics aren't so readily available for all of them. As a side note, the KEF B139 does look to be the correct part for the TLS80.

 

[KEW]

Simple!
I right clicked on your image and chose "Search Google for this Image"!

What you got there is....

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Drum roll
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Wait for it!
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Grape Crusher!

But seriously, if you then add IMF to the search box, you get some good hits:
https://www.google.com/search?tbs=simg:CAESfhp8CxCwjKcIGmAKXggDEijfDPMMhw3gDIYN9AzyDIsB2wXvDNE1oTPVNdI14yfPNfQn3SfoNdY1GjBzn6VbEgvqRllIm0uB8Bs0zM8acGDadS6en3T3l26nwgqhyzGePfx-PfpuKC0S4Y8MCxCOrv4IGgoKCAgBEgSFV9eEDA&q=imf+&tbm=isch&sa=X&ei=C2BKVbOcCYW4sAXjyoHYBA&ved=0CCsQsw4&biw=1366&bih=667

On the first page, I only found these two with both, oblong woofer and oblong tweeter. Both link to foreign sites. The first one is in French (maybe MDT is the model?) and requires registration before you can review. The second is in a language I don't recognize.

PS: Use the right click on image, and "search Google for image" trick to go straight to sites.

 

[zieglj01]

They do look interesting

 

[zieglj01]

Maybe a little more info here

http://www.t-linespeakers.org/classics/TLS80/

http://p10hifi.net/planet10/IMF_TLS80_brochure.pdf

 

[zieglj01]

Any help with identifying what I've got will be much appreciated. They sound awesome, but not knowing what they are is frustrating.

The world moves fast - I would still try to relax and enjoy them,

 

[TLS Guy]

I have acquired a wonderful pair of IMF transmission line loudspeakers but I cannot identify which model I have.

I was sold these as TLS80s but they aren't quite the same:

1. The lower frequency tweeter is not the correct part for TLS80, it looks to be the part used in TLS50.
2. The KEF B139 woofer has a label on it (inside) which suggests is too old as it pre-dates the launch of TLS80.
3. The "aspect control" present on TLS80 and all later large IMF loudspeakers is not present and clearly never has been present.
4. The front cabinet design is closer to a PM than TLS80, in particular the ports at the bottom for the transmission line are incorrect for TLS80.
5. The crossover is not a TLS80 crossover, it's a much simpler design. It doesn't appear to have ever been changed so I don't think it is a home-made substitute.
6. The IMF badge on the front grilles (not shown in photo) simply shows "IMF". By the time TLS80s were made the bade showed "IMF Electronics".
7. The cabinets are slightly the wrong size for TLS80s, the height is about correct but the depth and width are slightly different.
8. The front panel which carries the drivers is not detachable, unlike a TLS80 front panel.

Any help with identifying what I've got will be much appreciated. They sound awesome, but not knowing what they are is frustrating.

Thanks
TimView attachment 15831

It is a TLS 80 but and early version. It has the B1309 6171 made from 1961 I think until 1973. In 1974 the KEF B139 SP 1044 was introduced. So the latest your speaker could be is 1974, and that would mean carry over drivers from 1973 production.

One other thing I should mention, is that there is a chance those speakers are 16 ohm and not 8 ohm. Most of the 6171 production was 16 ohm, in the later production they are 8 ohm. The SP 1044 are 8 ohm.

Until about 1970 speakers were generally 16 ohm. In the UK the first decent solid state amp was the Quad 303. That was introduced in 1969 and was 8 ohm. Prior to that time in the UK all higher end system were tube and 16 ohm. There was a lot of overlap in the 1970s often times with 8 and 16 ohm versions of the same speaker.