IMF owners thread!
- Thread starter canuckaudiog
- Start date
I think it was only the version iv that had the metal plate across the front (crossover is mounted on that with trim controls on front). My version 3 look more like yours but with the older crossovers and fiberglass damping material.Hi again,
scouting more around the net, I found a description/photo that matches the units I have - not the usual-looking RSPM with a metal plate on the front. Its on a posting of ebay and can be found here. It also gives some form of base date for this version.
IMF Professional Monitor Speaker Review, 1983, 2 pg, Complete Test | eBay UK
This is a reprint of an Audio Review from 1983! This review will have SPECS, COMMENTARY, DETAILS, and INFORMATION about the unit listed. . You won't be dissapointed! A piece of Audio History! I have THOUSANDS more Ads and Reviews on my Ebay Store. Email with ANY questions, THANKS! -Search for...www.ebay.co.uk
Have I discovered an unknown branch of the RSPM family?
Regards
Mike
Yvan_donald
Well-Known Member
Hi, but IMF have RSPM MK VII with the Steel plate , I bought the same crossover used on bay many years ago and they didn't say from what model it came from , now I know came from the last professional monitor this last PM have the mids up in a seal section compare the cardboard tube normally use. Suppose to be more isolate from the transmission line and the woofer.
madswitcher
New Member
Some more information for any interested parties. It looks like the RSPMs I have are MK VIIs (or MK VIIIs 
) and probably the last series that IMF made before they went bust - most likely some of the cabinets that stood in the corridors of Reading University out of the way of company baliffs. The high serial numbers, 1702ML and 1702MR probably attest to this as well.
The drive units are all IMF marked and they have a single 'contour' switch on the rear that adjusts the mid and treble units a couple of dB or so from their nominal response. Thus, no metal panel on the front with 2 switches as other versions have..
I am gettting a set of replacement caps from Falcon Audio to see how re-capping works as the bass response (un-recapped) is nowhere near as good as my B&W 801SIIIs with an alignment filter which is- about -3dB or so at 17 Hz. It could also be that I need to get them up on a couple of bricks as I don't have stands for them.
For information I have attached a copy of the crossover. Note no reisistors in series or in parallel with the drive units (except for the adjustment control), 7 inductors and 12 caps.
Will report back when I have recapped them.
Happy listening
Mike
) and probably the last series that IMF made before they went bust - most likely some of the cabinets that stood in the corridors of Reading University out of the way of company baliffs. The high serial numbers, 1702ML and 1702MR probably attest to this as well.The drive units are all IMF marked and they have a single 'contour' switch on the rear that adjusts the mid and treble units a couple of dB or so from their nominal response. Thus, no metal panel on the front with 2 switches as other versions have..
I am gettting a set of replacement caps from Falcon Audio to see how re-capping works as the bass response (un-recapped) is nowhere near as good as my B&W 801SIIIs with an alignment filter which is- about -3dB or so at 17 Hz. It could also be that I need to get them up on a couple of bricks as I don't have stands for them.
For information I have attached a copy of the crossover. Note no reisistors in series or in parallel with the drive units (except for the adjustment control), 7 inductors and 12 caps.
Will report back when I have recapped them.
Happy listening
Mike
Last edited:
Tor-S
Member
Some more information for any interested parties. It looks like the RSPMs I have are MK VIIs (or MK VIIIs
The drive units are all IMF marked and they have a single 'contour' switch on the rear that adjusts the mid and treble units a couple of dB or so from their nominal response. Thus, no metal panel on the front with 2 switches as other versions have..
I am gettting a set of replacement caps from Falcon Audio to see how re-capping works as the bass response (un-recapped) is nowhere near as good as my B&W 801SIIIs with an alignment filter which is- about -3dB or so at 17 Hz. It could also be that I need to get them up on a couple of bricks as I don't have stands for them.
For information I have attached a copy of the crossover. Note no reisistors in series or in parallel with the drive units (except for the adjustment control), 7 inductors and 12 caps.
Will report back when I have recapped them.
Happy listening
Mike
Thanks for the crossover schematic. Looks like you have excatly the same filter as i have in my RSPM mk. Vii.
Your speakers are not RSPM but PM. They are the size as a TLS80 but clearly using Crossover and drivers from the RSPM mk. Vii.
These are quite rare. Only see a few for sale over the last years. Treat them nice.
Also. Can you post better pictures of the filters from both sides?
madswitcher
New Member
Hi Tor-S,
me being new to IMF nomenclarture,can you tell me what are the differences/advantages between the two?
Here are the two photos that you asked for (as best I can as the cables are short) but also the S/N plate that states they are RSPM and which I took to be genuine. You can see more photos in my earlier post above.
Hmmmm???
Thanks for any info on these
Regards
Mike
me being new to IMF nomenclarture,can you tell me what are the differences/advantages between the two?
Here are the two photos that you asked for (as best I can as the cables are short) but also the S/N plate that states they are RSPM and which I took to be genuine. You can see more photos in my earlier post above.
Hmmmm???
Thanks for any info on these
Regards
Mike
Attachments
Tor-S
Member
Thanks for pictures.
Im pretty sure that someone have added RS on the back side of the loudspeaker. I have never heard this speaker but the drivers are similar to the last IMF that was made. All drivers are ELAC. Its an interesting combination between RSPM mk. Vii and TLS80mk2
After a rather long while NOT listening to my RSPM MKIV, I connected them to a recently acquired Chinese Dartzeel clone (am I allowed to mention such a device here?) and BINGO - to my ears a match made in heaven. Before, with a a variety of different amps, I was always a bit dissatisfied - mostly with the highs - which caused a mild form of listening fatigue after a while. Anyway, with this amp the speakers sound wonderfully balanced and the highs are extended and very smooth. Next I am going to try a MC275 clone.
Wich amp?
madswitcher
New Member
Does anyone have a diagram of the Professsional Monitors' cossovers (I and II) that they can kindly post or point me to?
Kind regards
Mike
Kind regards
Mike
Might be in this 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...
audiokarma.org
Nashou
Yvan_donald
Well-Known Member
Hello and welcome , maybe Jeffrey " canuckaudiog " have an idea or from Falcon acoustics UK
madswitcher
New Member
Hi again Folks - a bit of a mystery continues:
Having had a chat with Jerry Bloomfield about these speakers he is of the view that they were probably some of the last pairs made by IMF during the phase where the company was probably being raided by baliffs due to unpaid bills. The unloaded cabinets were moved out to an adjacent business premiseses where the baliffs could not get their hands on them. Eventually they were moved to the basement corridors on Reading university and then made up into final products to try and regain some cash. - Thus, they are one of the 'Reading Pairs'.
They are the same size as the TLS80, i.e. slightly smaller than the RSPM, but were labelled as RSPM during their build. The units are all IMF (Elac?) and the crossover have more in common with the SACM Mk II than any other - the main difference being the super-tweeter section and some minor differences around adding of some resistors.
I have attatched a copy of the crossover circuit to spread the knowledge in case more of them turn up.
I have replaced all the caps as suggested by Jerry, including changing some of the low-value Bipolars to Polys, but there appears to be an unbalance in the units in that the output from the mid unit is quite high and the bass is lower that I expected (compared to my B&W 801S3s which are substantianally 'flat'). I have checked and double/treble checked the wiring and all is as it was before I did the work. I also compared an un-upgraded unit with an upgraded one and the unbalanced output remains although the upgraded unit does have some improvements over the other.
So, can anyone see any reason for the high output of the mid unit/low bass output and possibly how to fix it?
thanks for any help.
Having had a chat with Jerry Bloomfield about these speakers he is of the view that they were probably some of the last pairs made by IMF during the phase where the company was probably being raided by baliffs due to unpaid bills. The unloaded cabinets were moved out to an adjacent business premiseses where the baliffs could not get their hands on them. Eventually they were moved to the basement corridors on Reading university and then made up into final products to try and regain some cash. - Thus, they are one of the 'Reading Pairs'.
They are the same size as the TLS80, i.e. slightly smaller than the RSPM, but were labelled as RSPM during their build. The units are all IMF (Elac?) and the crossover have more in common with the SACM Mk II than any other - the main difference being the super-tweeter section and some minor differences around adding of some resistors.
I have attatched a copy of the crossover circuit to spread the knowledge in case more of them turn up.
I have replaced all the caps as suggested by Jerry, including changing some of the low-value Bipolars to Polys, but there appears to be an unbalance in the units in that the output from the mid unit is quite high and the bass is lower that I expected (compared to my B&W 801S3s which are substantianally 'flat'). I have checked and double/treble checked the wiring and all is as it was before I did the work. I also compared an un-upgraded unit with an upgraded one and the unbalanced output remains although the upgraded unit does have some improvements over the other.
So, can anyone see any reason for the high output of the mid unit/low bass output and possibly how to fix it?
thanks for any help.
madswitcher
New Member
Hi All,
I have a pair of 'racetrack' KEF B139 going for free. However, they are for personal pickup only - HP20 postcode - Aylesbury UK. Both tested at about 6.5 Ohms at D.C.
Any takers?
I have a pair of 'racetrack' KEF B139 going for free. However, they are for personal pickup only - HP20 postcode - Aylesbury UK. Both tested at about 6.5 Ohms at D.C.
Any takers?
Maybe I was wrong in posting my question about the IMF ALS 30 in a separate new thread. Probably many IMF owners will check the contents of this thread from time to time, so here’s a link to my question. Does anyone have experience with the sound of the ALS30?
Thread 'IMF ALS 30 filter issues? Help needed!'
https://audiokarma.org/forums/index.php?threads/imf-als-30-filter-issues-help-needed.1088538/
Thread 'IMF ALS 30 filter issues? Help needed!'
https://audiokarma.org/forums/index.php?threads/imf-als-30-filter-issues-help-needed.1088538/
Attachments
zibi079
New Member
Attachments
I wecome thoughts on the following.
I have aquired a pair of TDL Monitors that I plan to replace my IMF TLS50 mk1s with.
The IMF are very easy to live with, not fussy on placement and loads of low frequency extension, a hard act to follow.
My hope was that the TDLs would provide for better imaging due to the more modern speaker layout and even lower bass extension.
The problem I have is the bass extension is not nearly as good as with the IMFs.
All the drivers are working .My thoughts at the moment are maybe it's a room modes issue (something I've not had to deal with before), or less likely a recap needed. I recaped the IMFs so am fully aware of the potential benefits, but they did have those horrible oil/paper caps. Im not sure the TDL would benefit to any where the same degree.
Re room modes I'm still trying different speaker positions at the moment
If anyone has recaped TDL Monitor did it make any difference?
I have aquired a pair of TDL Monitors that I plan to replace my IMF TLS50 mk1s with.
The IMF are very easy to live with, not fussy on placement and loads of low frequency extension, a hard act to follow.
My hope was that the TDLs would provide for better imaging due to the more modern speaker layout and even lower bass extension.
The problem I have is the bass extension is not nearly as good as with the IMFs.
All the drivers are working .My thoughts at the moment are maybe it's a room modes issue (something I've not had to deal with before), or less likely a recap needed. I recaped the IMFs so am fully aware of the potential benefits, but they did have those horrible oil/paper caps. Im not sure the TDL would benefit to any where the same degree.
Re room modes I'm still trying different speaker positions at the moment
If anyone has recaped TDL Monitor did it make any difference?
zibi079
New Member
Many thanks Martinvb.