c-atle-79bay
Super Member
If I understand it correctly, yes, but I'm still not certain I fully understand it correctly.
IMF owners thread!
- Thread starter canuckaudiog
- Start date
SimplySound
Kent Engineering & Fondry
Well what if... just to try it out, you disconnect the Bass on the ESS and disconnect the Mid-Highs on the IMF's and then wire them in parallel and see how they sound? :scratch2:
In effect you'd still have both crossovers doing their thing... Ok, maybe you'd have a 3-5ohm load, but your amp shouldn't complain for the short while you did it... just to see how they sound. Then you can determine if you want to sink the time and money into an active crossover.
Just a thought... if I understand it correctly... but I'm still not certain I fully understand it correctly.
c-atle-79bay
Super Member
My non-committal response is related to something I read once on a going "active" with carver amazing loudspeakers and that you couldn't just remove the factory crossover and plug in the ribbon to the active crossover.....but I failed to understand the reasons and it was about a thousand thread reads ago.
canuckaudiog
On a quest for high fidelity
If it were me..
I would disconnect the tweeters from the crossover on the boards. Then, I would run an active crossover between the Heil and the passive crossover of the IMFs. Not sure where you would cross it over, this would depend on the performance of the Heil. So, I would find a frequency response graph (one must be available somewhere) of it and the Kef B110 SP1003 (or wait, does yours have the IMF Elac driver? either way should be similar in specs/response..) and then choose a frequency that makes sense.. and keep in mind too the phasing, which is the slope you decide to use. Not sure what is best here, I'd likely go with whatever slope the original IMF crossover used from the mid to the HF1300.
Hope that helps! And I am not sure if that'll work, but that's how I would approach it.
I would disconnect the tweeters from the crossover on the boards. Then, I would run an active crossover between the Heil and the passive crossover of the IMFs. Not sure where you would cross it over, this would depend on the performance of the Heil. So, I would find a frequency response graph (one must be available somewhere) of it and the Kef B110 SP1003 (or wait, does yours have the IMF Elac driver? either way should be similar in specs/response..) and then choose a frequency that makes sense.. and keep in mind too the phasing, which is the slope you decide to use. Not sure what is best here, I'd likely go with whatever slope the original IMF crossover used from the mid to the HF1300.
Hope that helps! And I am not sure if that'll work, but that's how I would approach it.
luvmusik
HOORAY !...ELECTRICITY !
Often wondered about experimenting with the high frequency response drivers on the RSPM MK IV and also exchanged about it on the imf yahoo group in discussion. Aside from also enjoying purist imf drivers to preserve the intended sound, I think there is always room to experiment and try new things too. Worth a try is the original series tweeter made by EPI/Epicure, the inverted airspring 1/2" concave dome tweeter developed by Winslow Burhoe. The first M-series hard phenolic design is the one to use; it flies under the radar in performance and as audio buy of all time. They are readily found on ebay at $25 to $35 each mint and photos of the different variations are on the humanspeakers site, seems to be a great match for the imf. The very first series tweeter is the one; this design currently has derived iterations today in Focal, Wilson and about 20 mfrs. It is one of the best tweeters I've heard and more than one can be combined for higher power situations. Very wide dispersion also - brilliant, clear, sparkling, articulate, correctly bright not brash, very "real" lifelike sounding of music and not fatiguing. I like the Heil idea also, so that, EPI, and the berylium Yamaha N1000 tweeter are great choices. Heil designs are again gaining interest in current designs. Two other pairings of interest, one was mentioned already is an electrostatic panel for highs and my favorite, a true ribbon tweeter...all ideas that may make imf RSPM really sparkle. Experimenting is welcome, would love to hear if anyone worked any of these combos...Heil, EPI/Epicure, Berylium Yamaha, stat panel, or true ribbon for the high frequencies and what the sonic results are on their imf's.
luvmusik
HOORAY !...ELECTRICITY !
My correction...the EPI/Epicure first original series line used the all-famous tweeter on a masonite base as a coated paper inverted dome, my favorite series tweeter. The 2nd line series tweeter used a phenolic inverted dome with ferro-fluid cooling and damping, also an excellent series. Never ran the two side by side as an A-B comparison, which would be real close and an interesting result, just as the relevance to the preceding posts about IMF experimentation with high frequency reproduction. Correcting my last post here about tweeter construction, sorry for any confusion, I had mixed the two series details in my typing originally.
SimplySound
Kent Engineering & Fondry
Shackman/Reromanus
Check these guys out!!!
And this almost looks like a TLS-80 with a Stat on top!!!
Check these guys out!!!
And this almost looks like a TLS-80 with a Stat on top!!!
Anyone near Philadelphia? There's a pair of RSPM Mk. IV improved in a CL listing along with some Tandberg electronics. Price is pretty good. I have no affiliation other than being a shameless IMF apologist and enabler.
I think this was asked before but what do people think of the TLS80 or TLS80 Mk. II as compared to the RSPM series?
I think this was asked before but what do people think of the TLS80 or TLS80 Mk. II as compared to the RSPM series?
canuckaudiog
On a quest for high fidelity
I had both for a while.
The TLS 80 II is a great speaker, but I felt the RSPM Mk IV was cleaner sounding and more emotionally conveying. It also digs a bit deeper and has a cleaner bottom end. The RSPM I found to be richer in sound as well, with more depth and detail to the sound. Basically, it's a step above the TLS 80 II in just about every way.
Interestingly, the only major difference between the RSPM and TLS 80 besides the cabinet, is just the crossover. Crossover points appear to be the same, and although I haven't studied the slopes, the only major difference I noticed was that the RSPM Mk IV uses mylar film capacitors paralleled with every capacitor for each filter. To my ears though, the RSPM is a good step above the TLS 80 II, so unless there are magic fairies inside the speaker making the music sweeter, that seems to be what accounts for the improvement in sound.
canuckaudiog
On a quest for high fidelity
Fellas, I recommend checking out the tune Toto - Bottom of Your Soul if you get a chance (from their newest album, Falling In Between). The huge bass drum has this visceral impact and you can feel the bass in your chest :yes: Great tune.
c-atle-79bay
Super Member
That sounds intriguing. There are been some MK IV around Seattle for a while now that I've wanted to try but would mean parting with my Fisher 500c, which I'm not ready to do yet. Have not tried my studios on the fisher yet either.
canuckaudiog
On a quest for high fidelity
It's a Teak veneer on the outside and a walnut veneer on the front.
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Curlycat
Member
Awesome! Thanks!!!
SimplySound
Kent Engineering & Fondry
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hunter00
Super Member
The fisher 500 is a nice piece but I like the advantage of 2 power transformers,1 for each channel with my tube amps.The dynaco mkiv's have great detail and slam and you cant beat mono blocks for detailed channel separation with stereo.the circuitry in these follows the dynaco mk2,and mk3 mono'sI also have a dynaco st70 tube amp,altho it provides great sonics it falls short of the monoblocks.My IMF als 40ii are perfect for tube amps!
tmarx
Active Member
Hi Everyone,
I recently became an IMF owner after scoring a pair of ALS-40II from the original owner through a local Kijiji ad. So far I'm impressed with the sound. I'm also very impressed with this useful thread, thanks to Jeff for starting it and sharing his experience.
My speakers are in pretty good condition overall, but the doping material on one of the mid-ranges has pulled away and cracked a bit. I'm wondering if anyone has seen this happen before? It doesn't seem to affect the sound. I seem to remember reading that replacements for this particular driver (with the white rubber surround) are hard to find.
The speakers are decidedly soft sounding right now, so my next step will be to recap them and see if that improves things. Does anyone happen to know the cap values or have a schematic? I have to order a bunch of caps some other projects so I don't think I'll go with the Falcon Acoustics kit.
Thanks
I recently became an IMF owner after scoring a pair of ALS-40II from the original owner through a local Kijiji ad. So far I'm impressed with the sound. I'm also very impressed with this useful thread, thanks to Jeff for starting it and sharing his experience.
My speakers are in pretty good condition overall, but the doping material on one of the mid-ranges has pulled away and cracked a bit. I'm wondering if anyone has seen this happen before? It doesn't seem to affect the sound. I seem to remember reading that replacements for this particular driver (with the white rubber surround) are hard to find.
The speakers are decidedly soft sounding right now, so my next step will be to recap them and see if that improves things. Does anyone happen to know the cap values or have a schematic? I have to order a bunch of caps some other projects so I don't think I'll go with the Falcon Acoustics kit.
Thanks
Attachments
canuckaudiog
On a quest for high fidelity
Like I said in the other thread, great pickup! I'm listening to my RSPM Mk IVs right now (and by the way, if you are ever in Edmonton you're welcome to stop by for a listen) and they're wonderful. They have a special richness and natural quality about them that is a challenge to find.
As for the doping, I wouldn't be too concerned, it's just aesthetics really. However I do believe that someone on pinkfishmedia knows of the original doping material, but I would say if it doesn't bother you don't worry about it.
By the way, could I ask for a favor? Is there any chance you could pull out one of the drivers with the white inverted surround and snap some pics of the basket and magnet? I have a set of ALS 40 II cabinets and unfortunately all the drivers are missing - I have spare tweeters mids and bass drivers but those mid bass drivers are impossible to find.
Anyway, I see you went through this thread so you know where to find all the necessary parts. If those mids have their original foam make sure you order that and get them done before they start to rub.
Also, those Audax tweeters have a tendency to dry out and lose SPL. I'm investigating a fix for them, I think there is a coating they used over the dome so I'm tracking something down. Otherwise just enjoy them, if they are sounding good that's what matters.
Sent from my iPhone using Tapatalk
As for the doping, I wouldn't be too concerned, it's just aesthetics really. However I do believe that someone on pinkfishmedia knows of the original doping material, but I would say if it doesn't bother you don't worry about it.
By the way, could I ask for a favor? Is there any chance you could pull out one of the drivers with the white inverted surround and snap some pics of the basket and magnet? I have a set of ALS 40 II cabinets and unfortunately all the drivers are missing - I have spare tweeters mids and bass drivers but those mid bass drivers are impossible to find.
Anyway, I see you went through this thread so you know where to find all the necessary parts. If those mids have their original foam make sure you order that and get them done before they start to rub.
Also, those Audax tweeters have a tendency to dry out and lose SPL. I'm investigating a fix for them, I think there is a coating they used over the dome so I'm tracking something down. Otherwise just enjoy them, if they are sounding good that's what matters.
Sent from my iPhone using Tapatalk
tmarx
Active Member
Thanks Jeff. I had a look inside one speaker last night. One of the things I want to do as part of my overall "refurbishment" is to flip the vertical orientation all the drivers 180 degrees so they start to hang in the opposite direction than they've been for the last 30+ years. The surrounds on the small mid-range are still healthy on my speakers; if you touch them they are soft and slightly sticky. I did notice the top surround and cardboard ring on one mid had pulled loose from the frame ever so slightly. After pushing the surround / ring back in place is seems to have stuck OK. I think the driver rotation will also assist with that sort of thing.
I did get a pic of the back of the mid w/ the white surround, see attached. I don't know if the info will help you track some down or not.
I also found the x-over board right behind the white surround mid, it has the following values:
4 MFD 50v
4 MFD 50v
60 MFD 50v
60 MFD 50v
Unfortunately there is just about zero speaker wire slack on the board, so it's going to be a serious PITA to remove this boards for the re-cap. I suspect I'll end up gutting all the wires and replacing them with something better. I also noticed discovered some more components on a board which is on the back of the terminal cup. It has was appears to be:
6 MFD 50v (correction, I originally thought it was a 16 with the 1 scraped off.)
12 MFD 50v
I did get a pic of the back of the mid w/ the white surround, see attached. I don't know if the info will help you track some down or not.
I also found the x-over board right behind the white surround mid, it has the following values:
4 MFD 50v
4 MFD 50v
60 MFD 50v
60 MFD 50v
Unfortunately there is just about zero speaker wire slack on the board, so it's going to be a serious PITA to remove this boards for the re-cap. I suspect I'll end up gutting all the wires and replacing them with something better. I also noticed discovered some more components on a board which is on the back of the terminal cup. It has was appears to be:
6 MFD 50v (correction, I originally thought it was a 16 with the 1 scraped off.)
12 MFD 50v
Attachments
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