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IMF owners thread!

beekeo said:
Visual inspection might be all you need to do, fingers crossed it is an obvious bad solder joint
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Found the problem...operator error! I had the Bass line going to the two bass drivers polarity reversed :rolleyes: It threw me because they didnt sound out of phase at all, just quieter than the other speaker. Anyhow, all sorted. Thanks for your input ;)
 
BassBias said:
I cannot find a schematic diagram of the crossover filter PCB of the IMF Super Compact II speakers. Who can help me?
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Might be in this thread.

redkiteart

Thread 'IMF Speaker Technical Details, Crossover Schematics, Rebuild Assistance'

Hello All

This topic appears to possess quite a strong interest among IMF owners old and new.

So as a suggestion perhaps we may gather the information scattered throughout the site and elsewhere on the web to create a database of technical information intended to assist those rebuilding this remarkable breed of speakers, large and small.

I shall begin with posting crossover schematics, thereon any technical details relevant to IMF.
  • Like

Athanasios
 
Nashou66 said:
Might be in this thread.

redkiteart

Thread 'IMF Speaker Technical Details, Crossover Schematics, Rebuild Assistance'

Hello All

This topic appears to possess quite a strong interest among IMF owners old and new.

So as a suggestion perhaps we may gather the information scattered throughout the site and elsewhere on the web to create a database of technical information intended to assist those rebuilding this remarkable breed of speakers, large and small.

I shall begin with posting crossover schematics, thereon any technical details relevant to IMF.
  • Like

Athanasios
Click to expand...
Noops afaics
 
Hello. Is there anyone in the group that can answer a few technical but long winded questions on the ALS40 speaker?
I recently acquired a pair of ALS40's (not MkII) and the upper 8 inch woofers were in sad shape and there is considerable mistrust if they are original.
I intend to rebuild the Crossovers using the original cap specifications if I can (haven't checked with Falcon Acoustics yet).
Question: Are the Crossovers between the ALS40 and ALS40 Mk2 similar in specification?
I have located a couple of likely replacement 8" speakers that I'm hoping might swap right in. option 1 are a set of 8" from a pair of Ditton 15's , and the other is a set of IMF 8" from an unknown model however they visually match what seen in images of the ALS40 Mk2 (ribbed cones).
 
Dustyxxx said:
Are the Crossovers between the ALS40 and ALS40 Mk2 similar
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The IMF40-IIs that I once serviced had 5 caps on a main filter board and 2 on a small PCB that was mounted behind the speaker terminal. ALS30 filters were the same as used in ALS40-I, if I remember well. Be careful about your choice, because IMF design is very critical with respect to filter tweaks (and of course driver swaps), which may have a huge impact on the sound. BW, Martin
 
Martinvb said:
The IMF40-IIs that I once serviced had 5 caps on a main filter board and 2 on a small PCB that was mounted behind the speaker terminal. ALS30 filters were the same as used in ALS40-I, if I remember well. Be careful about your choice, because IMF design is very critical with respect to filter tweaks (and of course driver swaps), which may have a huge impact on the sound. BW, Martin
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Thanks for responding. This sets has a 2nd small PCB mounted just below the Mid driver. I guess I'll start by swapping in new Caps of the same spec. I dont think my old ears would notice a difference between speakers.
 
Here is a mk I crossover 2 x 60nf, 2x 6nf. 1x 4nf. I thing the difference between mk I and mk II is probably in the coil , specially the midrange frequency the cut is at 350hz for the mk II and 375hz for the mk I , a bit more open in the mid section. That is the difference in the tls 50 and prof.monitor compare to the old version
 

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Yvan_donald said:
Here is a mk I crossover 2 x 60nf, 2x 6nf. 1x 4nf. I thing the difference between mk I and mk II is probably in the coil , specially the midrange frequency the cut is at 350hz for the mk II and 375hz for the mk I , a bit more open in the mid section. That is the difference in the tls 50 and prof.monitor compare to the old version
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This is the crossover from an ALS30, which had an ALS-II marking on its PCB.

1784504697380.jpeg
 
Yvan_donald said:
Here is a mk I crossover 2 x 60nf, 2x 6nf. 1x 4nf. I thing the difference between mk I and mk II is probably in the coil , specially the midrange frequency the cut is at 350hz for the mk II and 375hz for the mk I , a bit more open in the mid section. That is the difference in the tls 50 and prof.monitor compare to the old version
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Best pictures I have of the crossover without removing it at this point
 

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Both speakers are peerless, the bottom one with rough finish have old small magnétique, not ceramic, the one on top paper cone rubber suround, very big magnet, with like 1 1/2 " coil .usually it can be a kef b200 sp 1014 1" coil.
 

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Your photos it's a mk II not shure als 40 more like als 30 mkII, mk I dont have t-rap , the coils are glue to the bord. At the terminal I have a capacitor. 1nf 100v
 
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