IMF owners thread!

mech986 said:

Probably would work well within its power limits.

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Got the Nad C356BEE amplifier and I must say it is a great match for the TLS50's. It's like I found the "loudness button"

I would describe the sound as well detailed, crisp but not harsh. It has a feeling of space and presence. Stereo separation is very good. The amp has more than enough power and current to drive the speakers very well. I can listen to it all day long.

Curlycat said:

Got the Nad C356BEE amplifier and I must say it is a great match for the TLS50's. It's like I found the "loudness button"

I would describe the sound as well detailed, crisp but not harsh. It has a feeling of space and presence. Stereo separation is very good. The amp has more than enough power and current to drive the speakers very well. I can listen to it all day long.

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That's great to hear :thmbsp: I had figured the NAD would be a good choice for the IMFs.

Thanks for the update on the NAD, just aquired a sherwood S8000iii, which has quite a bit of low end punch, that I've yet to test with the IMF's. Thinking it may have some similarity to how NAD performs on the low end.

My 1 yo is cruising right now, so the IMF's are in storage.

IMF's don't seem to need huge power to sound good. They may sound better with more power, but sound is still quite good with lower powered receivers.

Using a Sansui 8D on my TLS 50's, and one option for my RSPM IV (through a speaker switch) is a Sony STR-6055 (only about 30W). Still sounds good. The RSPM's can also be powered by a 120W tube amp, but for background/casual listening, doesn't seem necessary.

The Studio's seem to have a lower rated requirement of 25-60ish. So they really allow a lot of choices. I did run them from my HT receiver (jvc rx-dp15) as an amp only 120 WPC and the results were quite good though..........still wondering about this setup.

canuckaudiog said:

That's great to hear :thmbsp: I had figured the NAD would be a good choice for the IMFs.

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A while back I hooked up a NAD 3020 to my TLS50's. I was curios to see how it will do, but not expecting much. I mean, its and old piece of kit and only 20W.

I was totally gobsmacked at how well the little NAD played with the TLS50's. I was not expecting that...It was giving my Yamaha A-S300 a run for it's money. That's when I figured a newer NAD will probably be a good match. I am very glad it's newer cousin is doing the same, just a bit better...

With amplifiers it's the quality of the wattage, not the quantity that you want. The nice thing about IMFs is they have a fairly easy load and can be driven with a large variety of amplifiers. I've run a Sansui AU-555a with my RSPMs and it sounded great - full-bodied sound and plenty of bass. The only issue was the amplifier ran out of headroom pretty quickly since my IMFs are in a very large space.


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I think I've found another synergistic combination for the IMFs.

This past Monday my Primare i30 that I've been waiting for finally arrived. I bought this for my dedicated listening set-up, which has my LS50s in it. Of course, how could I resist trying it with my IMFs? Well, I hooked it up tonight and decided to watch Toto's 25th Anniversary Tour. I have NEVER heard my IMFs sound like they did tonight. Unbelievably smooth and open mid-range with delicate and refined treble, and of course that incredible, open sounding bass IMFs are known for, but with the Primare it was controlled and rich. It's like the two are complementing each other almost perfectly. I've been listening to this amp on my LS50s and it does not sound like it did with the IMFs, that's for sure!

I think a large part of why the two work so well together lends to the neutral tone of the amp. The IMFs are a neutral sounding speaker and the Primare a neutral sounding amp - I think if I use a colder or warmer amplifier it takes away from the magic of the IMFs. At least, that's what I'm experiencing right now because I am using a Sansui AU-555a as a pre-amplifier which is providing a warmer sound than I would like with the IMFs. The power amp, a Marantz MM7025, is a bit on the clinical side, however the two aren't balancing each other out. I really need to get the Kenwood back out here, because unfortunately this Primare ain't stayin' here!

Anyway, I just wanted to comment on the combo. This Primare and my IMFs are makin' music babies together, man.

canuckaudiog said:

I think I've found another synergistic combination for the IMFs.

This past Monday my Primare i30 that I've been waiting for finally arrived...

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Man we do think alike... good to hear the Primare/IMF combo's doin' it for ya!!!

I've been diggin' the Primare DVD30 I just scored. Primare, never heard of them until about a month ago! What a class act they produce. Not cheap but the deals are out there! :thmbsp:

SimplySound said:

Man we do think alike... good to hear the Primare/IMF combo's doin' it for ya!!!

I've been diggin' the Primare DVD30 I just scored. Primare, never heard of them until about a month ago! What a class act they produce. Not cheap but the deals are out there! :thmbsp:

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It's really too bad because the Primare is actually for the Kefs, but I sure couldn't resist trying it with the IMFs!

But yep, great minds do think alike That DVD30 would be on the top of my list if I was looking for a good media player. I think I'm going to take a look at the R30 phono stage from them, however.

canuckaudiog said:

With amplifiers it's the quality of the wattage, not the quantity that you want. The nice thing about IMFs is they have a fairly easy load and can be driven with a large variety of amplifiers.

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I am getting the Maverick A1 Hybrid Tube amp with 20WPC, maily to use as a headphone amp, but of course I am very keen to hook it up to my TLS50's. Will report back when I have received it.

Anyone has any experience with the TLS50's and tube amps?

Curlycat said:

I am getting the Maverick A1 Hybrid Tube amp with 20WPC, maily to use as a headphone amp, but of course I am very keen to hook it up to my TLS50's. Will report back when I have received it.

Anyone has any experience with the TLS50's and tube amps?

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Excellent choice!

As for tubes, I don't know if this is accurate or not but I spoke with someone who sold IMF speakers in Britain back in the 70s and he told me that IMFs were actually voiced using Radford tube amplifiers (and in fact, he owned one, and planned to bring it over one of these days so we could try it with my RSPMs). Again, I don't know if this is true or not, but he seemed very credible and certainly knew what he was talking about.

IMF made in Telford Shropshire?

I don't own the tls 50's but with my IMF als 40aii my tube amps really shine.
Im using a pair of Dynaco MKiv mono tube amps /dynaco pas 2 tube preamp on them right now in my bedroom system.They sound equally good with my Eico integrated tude amp.
The dynaco's push 35 quality wpc and the als 40aii put a smile on my face daily;
hunter

hunter00 said:

I don't own the tls 50's but with my IMF als 40aii my tube amps really shine.
Im using a pair of Dynaco MKiv mono tube amps /dynaco pas 2 tube preamp on them right now in my bedroom system.They sound equally good with my Eico integrated tude amp.
The dynaco's push 35 quality wpc and the als 40aii put a smile on my face daily;
hunter

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Man, that is some really cool kit you have there. Love the Dynaco MKiv mono tube amps. I bet they do sound lovely!

canuckaudiog said:

Excellent choice!

As for tubes, I don't know if this is accurate or not but I spoke with someone who sold IMF speakers in Britain back in the 70s and he told me that IMFs were actually voiced using Radford tube amplifiers (and in fact, he owned one, and planned to bring it over one of these days so we could try it with my RSPMs). Again, I don't know if this is true or not, but he seemed very credible and certainly knew what he was talking about.

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Thanks! I am very glad to hear the Maverick A1 is a good choice Will deffo report back on the sound and performance.

Professional Monitor mk3 new owner

Just joined the IMF club with MK3 Professional Monitors. With less than two days worth of listening I have noticed a small distortion from one of the woofers (racetrack type) that is distinct on certain tracks - 'Albatross' being the most obvious.

There are replacement B139s on eBay but I wonder if someone can talk me through how to replace a woofer. Never attempted to do anything like it before but I'm sure I can manage. I've tried taking out the four screws but the woofer stayed resolutely in place. Do I just need to apply more force or take out the whole of the front of the speaker?

On another subject, can someone explain why front ported speakers such as these would be very room dependent that I keep reading about. Working towards a new space that will be an odd shaped room; narrow but high (pitched) ceiling (used to be a garage).


UPDATE:
I've got the woofer off with some tentative prising. Obviously I don't know what I'm looking for but just the act of taking it off and putting it back seems to have cured most of the distortion I was hearing. Not all but I now have to put my ear up against the woofer to hear it. Anyone know why this would be?

Braidy said:

Just joined the IMF club with MK3 Professional Monitors. With less than two days worth of listening I have noticed a small distortion from one of the woofers (racetrack type) that is distinct on certain tracks - 'Albatross' being the most obvious.

There are replacement B139s on eBay but I wonder if someone can talk me through how to replace a woofer. Never attempted to do anything like it before but I'm sure I can manage. I've tried taking out the four screws but the woofer stayed resolutely in place. Do I just need to apply more force or take out the whole of the front of the speaker?

On another subject, can someone explain why front ported speakers such as these would be very room dependent that I keep reading about. Working towards a new space that will be an odd shaped room; narrow but high (pitched) ceiling (used to be a garage).


UPDATE:
I've got the woofer off with some tentative prising. Obviously I don't know what I'm looking for but just the act of taking it off and putting it back seems to have cured most of the distortion I was hearing. Not all but I now have to put my ear up against the woofer to hear it. Anyone know why this would be?

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Congratulations and welcome to AK!

There is the possibility that the seal on the woofer was poor. Another possibility was that the woofer may need to be turned 180 degrees to compensate for some slight woofer voice coil sag.

If you have the oval woofer with full oval frame instead of the eared frame, yours is the early model (KEF B139 type 6171). The later KEF B139 SP1044 has better power handling and is a bit more robust. If you can snag a pair, it might be a nice upgrade and / or good for spare parts if you ever overdrive them.

A nice recap of the crossover should do wonders as your speakers are from the early 70's.

And we'll cajole you to provide some picture because

:worthless

Thanks very much. I did wonder about the different designs of the B139. That would involve some modification to the cabinet though, I'd think?

Bit embarrassed about the room these huge speakers are currently in as I'm temporarily back at my mothers whilst my new place is worked on but I'll think about pictures ....

Actually, you can see them in these dark pictures of the auction I won. http://www.ebay.co.uk/itm/191153055157?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Braidy said:

Thanks very much. I did wonder about the different designs of the B139. That would involve some modification to the cabinet though, I'd think?

Bit embarrassed about the room these huge speakers are currently in as I'm temporarily back at my mothers whilst my new place is worked on but I'll think about pictures ....

Actually, you can see them in these dark pictures of the auction I won. http://www.ebay.co.uk/itm/191153055157?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

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Welcome to the club :thmbsp:

For the distortion, I'd try what mech has suggested and rotate the woofer. That may solve it. A bad seal sounds more likely, however.

As for replacing with the SP1044 I'd be hesitant to do that. Reason being there could be differences between the two (the 6171 and the SP1044) and the crossover may only work best with the 6171. The good news though is the 6171 can be fetched cheaper than the SP1044.

Looking at the auction it looks like the crossovers are already recapped! That's great - you don't have to do a single thing to these speakers, they are ready to be enjoyed in full. Well done.

I personally own the next version of your IMFs, the Mk 4. They're fantastic sounding speakers.