IMF owners thread!

[mech986]

Are we sure which HF1300’s used in RSPM Mk IV’s are impedance wise, 4, 8, 15-16, or 32 (very rare)? If anyone has a Mk IV, could they pull it and photograph it and measure them? As noted above, others can be made to work, or the crossover values modified to use non-OEM impedance version. Sorry to hear Jerry has not been answering, the UK Covid situation still hasn’t turned around. Hope he and Malcolm Jones are ok.

personally, while Yvan’s offer is very generous, I would wait a bit and see if the HF1300 in 8 ohm shows up, there are ways to scare up some (like I’ll look in my stash too) by requesting them at various sources here in US, Cañada, and UK. Changing out dome assemblies is not easy and there is no guarantee that a plastic soft dome will mimic the HF1300 hard dome in response or impedance.

Yes, and thank you. But thats only a single driver, I would need two.

Yvan, are the hf2000 super tweeters in the Mk3's supposed to have a cover of some sort over the domes? Do you have a good pic of one or better yet, do you have one that could be scanned and 3d printed? That would be a piece of cake for most any 3d printer. Ditto covers for the hf3000.

3D printing for the HF1300 maybe, The perforated covers for the HF2000 are made from very thin brass perforated sheet, probably about 0.3mm thick with holes about 0.2mm diameter. I’m very unsure whether a 3D printer could print that thin in either plastic or metal and whether it could resolve the tiny perforations / holes. You’d probably have to chase the holes with a tiny drill. The thickness and hole diameters affects the way the cover works acoustically with HF frequencies. A 4-cutout version is used to cover the KEF T27 tweeter used in the BBC LS3/5a (see below). In the LS3/5a design, the designers mentioned that beside protection afforded, the cover actually increased and extended the T27’s HF output. So getting properly made versions is important.



There have been a number of reproduction sources on eBay over the past 5 years.

https://www.ebay.com/itm/LS3-5A-LS-...-/114769676536?_trksid=p2349624.m46890.l49286

Not the cheapest price but pretty close to the originals.

 

[mech986]

@Slapshot did you have pics and notations about the old drivers that were in your RSPM Mk IV’s? Are the speakers the original Mk IV or the Mk IV improved? Reason is early versions of the RSPM Mk IV used the oval KEF B139 SP1044 with flat front expanded polystyrene cone while later versions and the improved versions used the oval IMF 128/20 woofer with fiberglass cone and normal dome dustcap. Despite superficial oval with mounting ears shape, they are not interchangeable size wise. it was also my impression that the IMF KEF B110’s that were used had extra doping applied to the cones, making them look very pebbly and rippled compared to the slightly wavy appearance of the normal KEF B110.

So I’m assuming you ordered new Falcon B139’s and B110’s to replace the old ones? Were you also replacing the Celestion HF2000 with a Coles 4001K?

see enclosed pics of later RSPM Mk IV with IMF woofer

Were you using this thread as a plan for your refurbishment?

https://pinkfishmedia.net/forum/threads/imf-rspm-iv-refurbishment.198968/

 

[Rmac587]

Hi Rmac.., the second one, found on Ebay like couple years ago.

Hi Yvan,
I’ll message you so as not to clutter the thread. Thanks!

 

[Andrew Chan]

Hi all have a pair of IMF RSPM mkiv and have some missing knurled caps for the front face plate. Can I ask if anyone know the thread type for the as I have taken them down to several nuts and bolts places and they have no idea what thread it is metric or imperial. I am down in Australia by the way.

Cheers

 

[petervv]

no affiliation to seller, price seems reasonable:

https://www.ukaudiomart.com/details/649599361-celestion-hf-1300-mk2-nos-8-ohms/

 

[petervv]

no affiliation to seller, price seems reasonable:

https://www.ukaudiomart.com/details/649599361-celestion-hf-1300-mk2-nos-8-ohms/

sorry, didn't see the add is marked 'sold

 

[IMF_Pioneer]

Hi all have a pair of IMF RSPM mkiv and have some missing knurled caps for the front face plate. Can I ask if anyone know the thread type for the as I have taken them down to several nuts and bolts places and they have no idea what thread it is metric or imperial. I am down in Australia by the way.
View attachment 2233180
Cheers

Where did you manage to find these Andrew ? .......................Adelaide by any chance ?

 

[Andrew Chan]

Where did you manage to find these Andrew ? .......................Adelaide by any chance ?

Ah your memory must be slipping! I got these in Sydney a few years ago. Your were one of the first people I called when I got my hands on these I was so excited!

 

[Andrew Chan]

Hi all have a pair of IMF RSPM mkiv and have some missing knurled caps for the front face plate. Can I ask if anyone know the thread type for the as I have taken them down to several nuts and bolts places and they have no idea what thread it is metric or imperial. I am down in Australia by the way.
View attachment 2233180
Cheers

I got onto Jerry from Falcon acoustics and the thread used in these screw are likely BA thread, typically used for machine screws. I will check out a few hobbyist machinist shops and see what I can find.
On the very off chance any of the fine members here have any of these caps spare I would definitely be interested!!
Cheers

 

[IMF_Pioneer]

Ah your memory must be slipping! I got these in Sydney a few years ago. Your were one of the first people I called when I got my hands on these I was so excited!

Yep it's all coming back to me now. I just thought these were a set you had just recently picked up as a set was sold here in Adelaide just a week ago and went back to Melbourne, but as we've just spoken on the phone it wasn't you that bought those.

 

[IMF_Pioneer]

generally it's all about local content back in those days, not like now where most things are sourced from, you guessed it............................................China.

 

[Yvan_donald]

Hi, I'm surprise, my two pairs of MK III have 10-32 thread screws, this is the standard, Yvan.

 

[montrecott]

Did some work on the Super Compact II cabinets recently which seemed to help with the light scratches. I was told a previous owner had these restored by Midwest Speaker in Minneapolis with crossovers from Falcon Acoustics. Anyway, they sound excellent to me.

If you do a search of these online you'll see comments about them needing a lot of power but I haven't found that to be true. Mine sound really good with a Yamaha CR-1020 (which is about 75wpc) in a medium-sized room. What are others using for amplification?

 

[IMF_Pioneer]

I've never considered them to be overly thirsty, admittedly I do now run them on a Pioneer SX-1050 which is a 120 watt rms amplifier, but I've run them on much less powerful units with great success.

BTW you have a very nice set there. Many are very knocked around after all this time.

One thing I wished they did with the Mk II's and that is make them look like most of their larger speakers with an ally strip around the frontal area opposed to that very dated chamfered front which they sported for many years.

 

[rogermatthew]

Hi guys - HERESY! Sorry, but I've just got myself a pair of new PMC Fact speakers to replace my IMF TLS50IIs. I have loved my IMFs for over 40 years but I did some serious auditioning and plumped for the PMCs. Despite my IMFs being in immaculate condition and having been recapped, there is no question that technology has moved on over the past 40 years. A bit of nostalgia to see them go, whenever, but music is one of my main enjoyments in my declining years! Still, it's been a fascinating ride looking at all the posts, I wish every IMF owner well, and I shall look in from time to time. Thank you everyone, and my best wishes

 

[montrecott]

I've never considered them to be overly thirsty, admittedly I do now run them on a Pioneer SX-1050 which is a 120 watt rms amplifier, but I've run them on much less powerful units with great success.

BTW you have a very nice set there. Many are very knocked around after all this time.

One thing I wished they did with the Mk II's and that is make them look like most of their larger speakers with an ally strip around the frontal area opposed to that very dated chamfered front which they sported for many years.

An SX-1050 would generate a lot of sound with these! I've also used mine with a Pioneer SA-9500 MkII (similar sonics to your receiver, just not as much power) and a Tandberg TR-2055 (55 wpc) with excellent results. Moderate efficiency gives more amplifier options than a lot of British speakers from the eighties and nineties. I'd like to find a different mid-powered amp to try them with. Note: the room they are in is 14' x 14'.

You are correct, mine are in really nice shape. I was very fortunate when a fellow AKer here in Chicago sold them to me at a great price a couple of years ago. They are fairly rare here in the US, and it's even more rare you see a pair in this condition. Most KEF and B&W models from that era pop up here frequently. Not these. I have a tendency to buy and sell a lot of speakers but I consider these keepers.

 

[IMF_Pioneer]

I had 4 sets of these here in Australia where they are more common than in the USA that's for sure, but still no where near as common as they are in Europe.

One set was the original variant that used the KEF B200 and the other earlier drivers in the Midrange and Tweeter department along with a different Crossover, but I found that the Mk II was much superior to the Mk I in many ways.

I have refinished one set of Mk II's and moved them on and then I sold the original Mk I's I had and have decided to stick with the Mk II's sitting alongside a set of CM3's that I run in tandem. Yes I hear all the purists yelling at me for running two at the same time, but in the back room system that I use it sounds wonderful running the two sets at the same time. My ears are the proof of that. My main system has the RSPM Mk IV's (Improved's) and TLS-80 Mk II's in situ which I only run one set at a time depending upon what music I'm playing.

One day I'll finish off the set of HPCM's that I have and give those a run in the back room, but first I have to get my LP12 back into my main system that's still sitting in the set up jig.

 

[Andrew Chan]

Hi all with the mkiv non improved versions. As the KEF sp1044 and the 5/36 mids are definitely 8ohms. Is it safe to say the
Celestion hf1300 and hf2000 super tweeters are 8ohms as well?
My hf2000 diaphragms are looking a little worse for wear and thinking they need replacement. Only place that have the diaphragms in different ohms is the French Ebay seller.

 

[1303]

To continue my resurrection of a pair of IMF Studio Monitors. I replaced what the PO used (a pair of low quality 8" woofers that were made in Taiwan) with a pair of SP1063s. It worked but the bass was not sufficient as these are meant to be Transmission Line setup. I think I may need to find a pair of SP1039s or even a pair of SP1054s. What do you guys think?

 

[IMF_Pioneer]

As these are SM's, they would've had the full contingent of Elac drivers and no KEF units. I see you you've been communicating with Andrew on FB.