IMF "The Compacts"

[defektzero]

Yes .... Hi & Sorry for th late answer!

Looks like it´s an IMF / ELAC 8/28 BR. This late version with the "rips" you find at the IMF ALS 40 II. Please check the diameter of the voicecoil.
This are the only specs I have:

You can find it at the Falcon-Acoustics site also...

Grüssle Henner

 

[defektzero]

You should have in mind, that the old ELACs (and KEFs too) go out of specs, because of the rubber surround getting harder. If you want too use them, they need a looong play-in. I suggest to do that, befor testing them in an enclosure...

 

[mot]

thank you, very helpful.

 

[Wfm333]

I have the TLS80s. I found they really still compete with modern offerings. Ttied some klipsch RF7iii and jbl monitors (14k rrp) still found the 80s went way lower and were better allround to my ears.
Now i really love the super compacts mk 2 and the bass and mid slam is superb. Much tighter and punchy than the 80s. Unfortunately the super comps run out of headroom pretty quick around 70db listening levels
Just wondering if the ALS40s or tls50s would sound more like the super comps
But with more headroom ?
Or any other suggestions to capture that super comp sound would be great. The combo of deep punchy bass, smooth mids and silky highs are just what im after. They never cease to amaze me and are my favorite speakers since i found them over 20 years ago!

 

[U102324]

I had my KEF Concerto for some 50 odd years and they just seem to get better. What I do is rotate the speakers through 180 deg. every year or so and the cones have not sagged nor does the surround get stiffer. They are in every day use. Sometimes I listen to LS3/5a's when the wife goes to bed and don't want to shake the room with bass. I do the same procedure with the B110 woofer and they too still sound like I bought them yesterday. I have measured the caps a year or so ago and they where within spec.

 

[Wfm333]

Is there any difference between the Als40 mk1 and MK2 And 2a ? I know the 2a is more desirable and imf website states that the Mkii is phase matched with bigger models. There is not much info regarding xo differences or tonal differences between the 3 Als40 models.

 

[Martinvb]

The IMF Compacts

This Thread is about the smaller models of IMF. Some years ago, I just wanted to test the "IMF house sound" - I planned to buy one of the big transmissionline models of this manufacturer but than a pair of the smaller 3 way Super Coompact II came my way and I decided to buy them for small money, because they had the same mids and tweeter as their big brother. Since then I´m listenig to them and some other compact IMF speakers.

I want to start with the 2-way Compact II:
View attachment 1209380


The tweeter is the well known KEF T27 that is also used at the little LS 3/5a BBC monitor.
The mid/woofer ist an coated version of an Audax:

View attachment 1209381


...and this is the crossover:

View attachment 1209382

The original capacitors are a typiclal electrolytic "elcap" (C1) and a Philips "chicklet" Type 341... (C2). Together they work far better, than one might guess.

Because of the age, it´s better to replace C1 - otherwise you have to listen 20 to 30 minutes untill it wakes up and the stereo image might not be very symmetrical. The little Philips is usally not on the end of its lifetime. The crossover is glued to the damping foam, wich is a big mess, if you want to clean it for soldering. After the repair it´s better to fix it on the bottom of the speaker ( you will need longer wires then ).

If you aim to an "next to original restauration", the english company Falcon Acoustics sells Replacements, that seem to have a little lower ESR and you might want to use a 1 ohm resistor to balance that.

It may look like this then:

View attachment 1209401


But it´s not recommended to use the original circuit bord, because it is very weak and the conductors loosen from the pertinax board. I rather use something solid like that:

View attachment 1209406

Now I´m hungry ... the thread will continue very soon 😉

Hi, thanks for this very interesting information. I just bought a set of these Compact IIs and am very impressed with the sound. I would like to try if replacing the C1’s has audible benefits, so I ordered caps to test this, including the 1 Ohm resistors that you suggest. It is not entirely clear to me where you placed these resistors: are they simply in series with C1 to correct for the lower internal R of the cap? Your help is much appreciated. BW, Martin

 

[Martinvb]

@defektzero I took a closer look and decided that the resistor should indeed be inserted with the cap. I ordered 6,2 uF / 100V caps from Jantzen and several resistors. Best audible results were with 8 Ohm (20W) resistors. This was confirmed in the REW measurements, that showed some 5-8 dB attenuation in the higher frequency range. Very happy with this adjustment!