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IMF owners thread!

Braidy said:
Thanks. I'll stick to the older B139, then.

Is the mk4 a significant upgrade to the mk3? Not that I'll be upgrading soon, I hope.
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I wouldn't say significant, no.

The major differences between the two models is basically they switched to a different cabinet maker at this point. The internal foam is different, in the MK4 you have an egg crate foam whereas I believe it's some sort of fibreglass or rockwool inside the MK3. I'm not sure if the transmission line changed, but due to the cabinet dimensions being a bit different I would say this is possible.

The other difference is that the MK4 uses the SP1044 Kef. I think the other drivers are identical, although it is possible the Celestion tweeters could be a later version.

Finally, the other difference which is the main one is the crossover. The crossover on the MK4 is quite a bit more complicated with more adjustments available and also they changed the slopes and crossover points. This is where you will find the most difference between the two models.

So yeah, significant upgrade I wouldn't say so. Some prefer the older MK3 to the MK4, and of course vice versa (your mileage may vary). :-) I wouldn't go hunting for a pair if I had a set of MK3s, but then again if a set came up for sale I don't think I would be tempted to resist either!
 
Good to know. Thanks for that. If one turns up locally it may be worth investigation but I'm not going to do another 340 mile trip for a MK4.
 
Can anyone tell me why front ported speakers such as these need space around them? Just wondering how they are going to react to my new place (narrow and high). I could probably get them away from the back wall a little but they will be tight against the side walls.
 
Braidy said:
Can anyone tell me why front ported speakers such as these need space around them? Just wondering how they are going to react to my new place (narrow and high). I could probably get them away from the back wall a little but they will be tight against the side walls.
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It has nothing to do with the bass, although I wouldn't put speakers with ports facing any direction close to a wall - the bass would be exaggerated and you certainly don't want that with a fine bass reproducer like the IMFs.

What it has to do with is reflections from the walls. The closer the speaker is to the wall the worse the imaging gets. They call this comb filtering where the sound wave produced by the speaker and the reflections from the walls, ceiling, floor etc. confuse the listener as to where the actual sound is.

Bass is omnidirectional so, it doesn't matter if it's front ported, the bass will still become exaggerated if you put it in a corner.

Best thing to do is to just play around with the placement. I have mine about 10 feet apart, with 3 feet away from the nearest side wall and rear wall. I find they sound best like this.
 
Ah, that makes sense, thanks. I won't have any choice about the placement, sadly, so I'll just have to cross my fingers that they are ok.
 
Braidy said:
Ah, that makes sense, thanks. I won't have any choice about the placement, sadly, so I'll just have to cross my fingers that they are ok.
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If it helps, I do find the IMFs to be a lot less sensitive of room placement in terms of bass than most speakers.


Sent from my iPhone using Tapatalk
 
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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They look very nice, and the veneers look very well cared for and intact. The woofer in a couple of shots look a little asymmetrical, sort of sagging to 7 o'clock a little, might just be the angle of the photo. Yes, going to the SP1044 would require some work on the baffle to make it fit, or you could consider cutting a new baffle to accommodate them. IMO, I think the SP1044 would be an improvement but it is a little hard to implement.

As for the recapped crossovers, sounds great, but now you may need to get a look at the crossover, and find out what was used, and who supplied the crossover parts. Done right, they should be good, done poorly, well, that's a risk. Did the previous owner advise you of how they were done?

Here's a couple of the pics from the auction, I lightened them up a bit to show the detail.
 

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Thanks. Yes, those pictures were very dark but, as the auction says, you don't buy formica mk3s for their looks. Cabinets are excellent, actually. No noticeable scratches but maybe thats the advantage of formica. The only damage is to one back corner that looks as if something heavy landed on it.

The seller did tell me where and how he got the caps redone but I've forgotten, of course. I'll send him an email. Very nice chap and family.
 
After quite a hiatus from picking up new IMF speakers, something has finally landed on the horizon.

Not exactly IMF, but very close. I managed to snag myself a pair of TDL RTL3s in a trade deal.

t3p_rtl3.jpg


TDL (Transducer Developments Limited) Electronics is the company that formed when IMF and Elac made a joint venture together to produce drive units for the later generation of IMF speakers and then eventually became a company producing full speakers. The history is a bit fuzzy for me, I need to do more research, but as I understand it IMF became defunct around 1983/1984, and then John Wright through some turn of events came back to TDL Electronics after his Ambisonics venture to produce more speakers. If I had to guess I would place the timeframe around the late 80s.

John Wright continued to design speakers until the mid-late 90s, and then his health got the better of him and he passed away in 99. TDL was sold to another company and the designs were not of John Wright (and worth staying away from). I don't know a lot about TDL, who worked there or with John Wright and exactly who contributed what, I just know John had a heavy hand in the design of most of the speakers when he was a part of the company.

Now, about the RTL3. These were made in the mid 90s, I believe the first year being 94, and being produced for a number of years. There are three iterations - the first is identified by the flat sides on the woofers and the grill extending to the bottom of the speaker, and the ports on the bottom being square. The second iteration has a shorter grill and a different shaped set of ports and different bass drivers. The third is like the second, but is a "Limited Edition" model. The RTL3 is also the second to the top of the line, the RTL4 being at the top.

TDL speakers in general seem to be even more scarce than IMF speakers. I'm not sure why this is, my guess would be their sales were not as good as IMF, but I have no idea. Maybe owners are very pleased with the speakers (which is likely) and do not want to sell.

Anyway, when these RTL3s cropped up I had to have them, despite all the negative comments made about them all over the web. Upon getting them buyer's remorse set in right away. The cabinets seem cheap and they don't weigh much. Did my love for IMF get the better of me with this trade?

I got them home and decided that I would listen first, judge second. It's a good thing I did because they in fact sound excellent. The words transparent, clean and clear come to mind. The bass could be better, and I think this is largely in part due to the thin cabinets. But, what these TDLs do, they do well. I feel like I'm back when I got the IMF TLS 50 IIs and falling in love with the IMF sound. These TDLs do a lot of things that I like, just like IMF speakers. They sound different in some ways, I feel like they resolve better detail, and the midrange is cleaner. Overall, definitely similar. I get why What Hi Fi gave them awards when they were new. In short I can easily recommend these if you happen to see a pair come up for sale. They go for little money, around $150, and you are getting very good speakers for that money.

I hope that I run into more TDL speakers, I've had lots of experience with IMF but not much with TDL. Next on the list will be a set of TDL Studio's with a true transmission line.
 
canuckaudiog said:
After quite a hiatus from picking up new IMF speakers, something has finally landed on the horizon...
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You never fail to amaze me Canucker with what you find around the great white north!!! :thmbsp:

Let us know how they sound compared to all the other systems you've heard!!!
 
SimplySound said:
You never fail to amaze me Canucker with what you find around the great white north!!! :thmbsp:

Let us know how they sound compared to all the other systems you've heard!!!
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Even more fortunate than the find itself was the fact I didn't have to shell out any cash! I have no money in the audio kitty so there was no other way I was going to snag these, unfortunately. Every dog has its day, as they say!

I'll definitely provide more comments about how they sound against what I have and have heard.

By the way, I don't know if anyone here has seen this, but I found this while fumbling around on the IMF Electronics website and it is definitely worth a read. It's essentially the white paper on IMF speakers, written by John Wright himself.

http://www.imf-electronics.com/Home/imf/imf-people/john-wright-article-part-1
 
IMF super guru's! I have some quick questions that I need to figure out within the next few hours for probably obvious reasons:

1. How available are Hiquophon 20mm drivers and what do they go for?
2. How good is a Fried G/2A and how does it compare to a Fried Model R?

A few of us are contemplating taking a shot at a local pair but one tweeter is shot. None of us know how easily these are sourced (it is noted that hiquphon still sells them but there is no price listed) or what the cost would be, if there are alternatives, etc.

If anyone has a few quick answers, post them up!

Thanks,

John
 
Thanks buddy, much appreciated. I will PM him but he may see this in any case, sm19422 has corresponded with me before in other threads. The Fried/IMF crew is one of the best on AK ;)
 
A little update on those TDLs.

Still no pictures, sorry guys! I was out all weekend so I didn't have time to snap any. I'll get some soon, promise :)

Anyhow, I decided to pull them into my dedicated listening room which houses my Kef LS50s, Primare i30 and the DSPeaker Anti-Mode. I wanted to see what these speakers would sound like with some quality amplification and also to see what happens when you correct the bass response. Plus this would give me a proper comparison against the Kef LS50s which to me is a somewhat interesting comparison.

So first of all after correcting the bass it became rather obvious to me the bright treble response that I have been reading about. It seems that the emphasized bass was masking this quality, or at least distracting me from it. Now with nowhere to run, it showed itself. The bass improved by a huge amount though, I'm actually much more impressed with it and feel it isn't terribly far off from what my IMFs bass sounds like.

I started to do some reading on the internet and some folks have performed crossover mods for these speakers which helped bring them into a more natural, balanced sound. The recommendation is to change the 10ohm resistor for a 33ohm resistor. I have a 25ohm resistor on hand I can try out, but the first thing I thought I would do is swap out the 6uF Alcap for a 6uF Solen polypropylene capacitor I have laying around.

I did what I normally did when I do any sort of cap changes or modifications and did one, and then swapped back and forth between the original speaker to see the difference it made. At first I wasn't sure, I was definitely hearing more detail through the tweeter but was it bright? I then put on Diana Krall's Live in Paris album, and played a couple of songs and it was very obvious to me that the speaker with the Solen was definitely better sounding. The original speaker sounded murky and foggy by comparison, Diana's voice didn't feel compelling whatsoever whereas through the Solen capped speaker it was a lot more believable.

OK, so then I decided to do the other one. Now we're talkin', this is better. The raspiness of the tweeter came down a lot and everything sounds much smoother. I still feel like there's a balance problem unfortunately, so more tweaking is going to be needed. Right now I'm running an EQ with 6kHz at -3dB and this sounds much better.

I'm a little disappointed to see that a speaker John Wright designed seemed to have some flaws out of the gates, but it's all about intention and execution. I'm guessing that John predicted people would want a speaker like the RTL sound, and perhaps that's what made it popular. For me though, I think I prefer the more natural balance I'm accustomed to from my Kef LS50s and big IMFs. I'm going to continue to mod these some more, and see if I can't get them singing like my IMFs or at least similar to them.

Either way, regardless of all of this, they ARE a fun speaker to listen to and depending on what you like, you might prefer the original presentation of the speaker.

Edit: After a bit more EQ tweaking, oh yeah, we are COOKIN'! I'm definitely not adverse to tweaking with an EQ, but jeez these speakers need it. Too bad the stereo they're going into doesn't really have this kind of capability, but ah well, what can you do. I'm sure the wife will love 'em all the same :)
 
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mech986 said:
As for the recapped crossovers, sounds great, but now you may need to get a look at the crossover, and find out what was used, and who supplied the crossover parts. Done right, they should be good, done poorly, well, that's a risk. Did the previous owner advise you of how they were done?
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Just heard back from the previous owner. He did the caps work himself which were supplied by Falcon. I did see (not hear) a set of IMF lookalikes (akin to the 50s I imagine) that he'd built himself and they looked great so I think he knows better than most what to do. I wouldn't know what I'm looking at.

Still not heard any more distortion from that woofer since taking it off and putting it back.
 
canuckaudiog said:
A little update on those TDLs...

I'm a little disappointed to see that a speaker John Wright designed seemed to have some flaws out of the gates, but it's all about intention and execution. I'm guessing that John predicted people would want a speaker like the RTL sound, and perhaps that's what made it popular...
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Somewhat like the KEF R104/2 or different? :scratch2:
 
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