Mods to RS-1B

EMIT tweeter Modification - monopolar -> dipolar

For those of you that are interested here is a link to my complete Infinity EMIT modification where I take 2 original Infinity monopolar EMIT tweeters and make them into 1 dipolar / bipolar EMIT.

http://launch.ph.groups.yahoo.com/group/InfinityClassics/photos/view/2a95?b=1&m=s&o=0

There are about 24 steps to the modification each one documneted in these photos.

This modification is NOT used in my RS1b modification because it is impractical with the existing RS1b cabinet....but when I build ribbons speakers from scratch...this is my preferred tweeter configuration.

This makes the EMIT tweeter just like the EMIM midrange...a true dipole.
Why Infinity never made them this way is beyond me.

I have been doing this modification for over 25 years and I swear by it.

If anyone has problems viewing these images please E-mail me directly and I can E-mail them to you.

Be amazed and enjoy.

MichaelAlanMarks@aol.com

Sticky for Docs mods ???

MagicMarksy said:

For those of you that are interested here is a link to my complete Infinity EMIT modification where I take 2 original Infinity monopolar EMIT tweeters and make them into 1 dipolar / bipolar EMIT.

http://launch.ph.groups.yahoo.com/group/InfinityClassics/photos/view/2a95?b=1&m=s&o=0

There are about 24 steps to the modification each one documneted in these photos.

This modification is NOT used in my RS1b modification because it is impractical with the existing RS1b cabinet....but when I build ribbons speakers from scratch...this is my preferred tweeter configuration.

This makes the EMIT tweeter just like the EMIM midrange...a true dipole.
Why Infinity never made them this way is beyond me.

I have been doing this modification for over 25 years and I swear by it.

Click to expand...

Hey Doc,

The link above takes me to a site that needs a login. I'm trying to minimize the number of places on the WWW where I have a login.

Do you suppose that we could figure out how to get you a STICKY here on the Infinity Forum for your mods? With the amount of research you have done and your background, it would seem to be a reasonable thing to have as a permanent reference here on AK ??

Maybe we could separate the business bit from the theory and application of the mods? Do you have mods for "lesser" Infinity models ??

Hey guys, what do you say :scratch2:

MagicMarksy said:

Great....as far as I am concerned all ribbons currently available today are really based on the original STRATHERN design. Some are bigger, some are smaller, some have more rows of magnets, some use a different diaphragm material, but they are all basically the same.

Click to expand...

Thanks, though those quasi-ribbons (as opposed to true ribbons, such as mine use, that are not bound on the sides like the drivers you mentioned) have older origins than the Strathern in the Blatthaler of the early '30s. I'm just kind of retentive about people calling these drivers ribbons when planar-magnetic is more apt in many of the cases.

MagicMarksy said:

Main differences:

IRS III: Clear Polypropoline dual voice coil woofers, 1000W servo amp for the subwoofer column (188,000 uF total), Senerium (sp?) cobalt magnets in EMIM's and EMIT's.

IRS V's: Gray impregnated plastic single voice coil woofers, 2000W servo amp for the woofer column (376,000 uF total), Nyodenium (sp?) magnets in the midrange and tweeters.

Click to expand...

Thanks, I was aware of the IMG woofers (Injection Molded Graphite cones that used graphite fibres impregnating the polypropylene), but that bit about the neodymium magnets is very interesting. I had thought the change over to neodymium from the old samarium cobalt occurred ~1992 with the EMIM High Energy (902-5339A) and EMIT High Energy (902-5228) drivers in the Renaissance series and later in the IRS Epsilon, which used the same drivers but changed the tweeter name from EMIT-HE to EMIT-B. I just took a look at the IRS V service manual and it still lists the 902-0012D EMIM as its midrange driver and the 902-3721 EMIT for the treble, both of which still used samarium cobalt magnets. Was there a revision later on in the run where Infinity switched to the 902-5339A and 902-5228, which don't match your pictures, or some new revision number for the '0012 and '3721 not listed in the service manual?

Regarding the amplifiers, the original 1.5kW (into 0.66ohms) amps for the first IRS were noted as being built to order by QMI. Were the IRS III and V servo amps built by them as well or was there a change in manufacturer?

Rereading your post, I see that you mentioned dual-voice coil woofers. Do these towers use Watkins woofers? I had the impression that from the original IRS, single voice coil woofers were used in the bass towers as the Watkins principle wouldn't work with the servo feedback or at least would be wasted. Looking through some of the information I've found, it would seem that both sets of bass towers are spec'd at 0.66ohms impedance, which had indicated to me that the basic drivers were the same, just with revisions in the cone material. How are the DVC woofers rigged to work with the servo control or wired up altogether?

MagicMarksy said:

For those of you that are interested here is a link to my complete Infinity EMIT modification where I take 2 original Infinity monopolar EMIT tweeters and make them into 1 dipolar / bipolar EMIT.

Click to expand...

I remember seeing your modification first posted at the group and I had a question I didn't get around to asking. How do you make sure the magnet polarities are properly matched between the fronts? I seem to recall that they are set to alternate in the original drivers and that the top and bottom are important to match to maintain the proper magnetic field going perpendicular to the diaphragm for maximum linearity. Hence the advantage of a push-pull design over single-ended planar-magnetic designs. Or are the drivers set up such that there is only one way that they can be assembled and that this is a moot point? It's a concern I developed while repairing a broken magnet in a 4x4 EMIT (902-0157) and initially gluing it in upside down resulting in half the diaphragm having much reduced output than the other forcing me to fight the little buggers and do it again the right way.

I'm also a bit concerned about diaphragm damping. I've read that the sealed back on the EMITs and felt strips were required to damp the diaphragm due to its desire to misbehave (resonance modes) a bit at the upper frequencies. The source, of which may be a bit questionable, indicated that the sealed backwave helped to improve the linearity of the driver. Have you found this to be an issue with your dipole EMITs? Any frequency response aberrations that show up afterwards?

Thanks,
- JP

Getting a Sticky Here - Sure why not - how do I do it?

BrocLuno said:

Hey Doc,

The link above takes me to a site that needs a login. I'm trying to minimize the number of places on the WWW where I have a login.

Do you suppose that we could figure out how to get you a STICKY here on the Infinity Forum for your mods? With the amount of research you have done and your background, it would seem to be a reasonable thing to have as a permanent reference here on AK ??

Maybe we could separate the business bit from the theory and application of the mods? Do you have mods for "lesser" Infinity models ??

Hey guys, what do you say :scratch2:

Click to expand...

I understand your desire to minimize places on the web where you need to log in and would be very amenable to getting a STICKY here. Anyone that know how to make it happen...make it happen....it is O.K. with me. But just let me say that the Yahoo Infinity Forum is also a good forum and many of you would be well off also joining that forum as well. There is a lot of good stuff there too. Can't have too many forums about these great speakers....In my opinion. So join.

My mods are not really specific to any Infinity model...it is more that I understand the drivers...how they work...and what they are capable of....I love ElectroMagnetic Induction Speakers and have many from all sources. I have worked with them since the early 80's and they are still my first true love.

For the IRS Series III's and V's I have many Mods...but the simplest one is Tri-Amping them and getting rid of the original Infinity Active and Passive Crossovers. They don't need much else. One could use my DIPOLE tweeters in the IRS Series III and V but it is such a big job for such a small gain that even I myself have never done it to them.

My favorite avenue is to start from scratch and build the entire linear driver line source dipole speaker system from the ground up. Then there are no artificial barriers and you can do anything you want. Only size and money determine the final outcome.

More on all this later.

Michael

So many questions so little time and space but I'll try

Charivari said:

Thanks, though those quasi-ribbons (as opposed to true ribbons, such as mine use, that are not bound on the sides like the drivers you mentioned) have older origins than the Strathern in the Blatthaler of the early '30s. I'm just kind of retentive about people calling these drivers ribbons when planar-magnetic is more apt in many of the cases.


Thanks, I was aware of the IMG woofers (Injection Molded Graphite cones that used graphite fibres impregnating the polypropylene), but that bit about the neodymium magnets is very interesting. I had thought the change over to neodymium from the old samarium cobalt occurred ~1992 with the EMIM High Energy (902-5339A) and EMIT High Energy (902-5228) drivers in the Renaissance series and later in the IRS Epsilon, which used the same drivers but changed the tweeter name from EMIT-HE to EMIT-B. I just took a look at the IRS V service manual and it still lists the 902-0012D EMIM as its midrange driver and the 902-3721 EMIT for the treble, both of which still used samarium cobalt magnets. Was there a revision later on in the run where Infinity switched to the 902-5339A and 902-5228, which don't match your pictures, or some new revision number for the '0012 and '3721 not listed in the service manual?

Regarding the amplifiers, the original 1.5kW (into 0.66ohms) amps for the first IRS were noted as being built to order by QMI. Were the IRS III and V servo amps built by them as well or was there a change in manufacturer?

Rereading your post, I see that you mentioned dual-voice coil woofers. Do these towers use Watkins woofers? I had the impression that from the original IRS, single voice coil woofers were used in the bass towers as the Watkins principle wouldn't work with the servo feedback or at least would be wasted. Looking through some of the information I've found, it would seem that both sets of bass towers are spec'd at 0.66ohms impedance, which had indicated to me that the basic drivers were the same, just with revisions in the cone material. How are the DVC woofers rigged to work with the servo control or wired up altogether?


I remember seeing your modification first posted at the group and I had a question I didn't get around to asking. How do you make sure the magnet polarities are properly matched between the fronts? I seem to recall that they are set to alternate in the original drivers and that the top and bottom are important to match to maintain the proper magnetic field going perpendicular to the diaphragm for maximum linearity. Hence the advantage of a push-pull design over single-ended planar-magnetic designs. Or are the drivers set up such that there is only one way that they can be assembled and that this is a moot point? It's a concern I developed while repairing a broken magnet in a 4x4 EMIT (902-0157) and initially gluing it in upside down resulting in half the diaphragm having much reduced output than the other forcing me to fight the little buggers and do it again the right way.

I'm also a bit concerned about diaphragm damping. I've read that the sealed back on the EMITs and felt strips were required to damp the diaphragm due to its desire to misbehave (resonance modes) a bit at the upper frequencies. The source, of which may be a bit questionable, indicated that the sealed backwave helped to improve the linearity of the driver. Have you found this to be an issue with your dipole EMITs? Any frequency response aberrations that show up afterwards?

Thanks,
- JP

Click to expand...

So what kind of speakers do you have? I do not even know? I also own Apogee DIVA's and they are great too, but even they are held on the sides by tiny stabilizing points..so some people do not even consider them true ribbons...although the midrange and tweeter are closer than the Stratherns or the Infinity EMIM's or EMIT's. I agree that the STRATHERN's, etc. are best called ELECTROMAGNETIC PLANAR DRIVERS. No question about it. That is what they are....I agree 100%...they are not true ribbons.

In the IRS series III each woofer has two 2 Ohm voice coils and they are wired in series so each woofer is 4 Ohms....then all the woofers are in parallel....to get the 0.67 Ohm load. With the IRS Series V's they use a single 4 Ohm voice coil on each woofer all wired in parallel so the result is the same. I heard somewhere who made the amps for infinity....I think William Legall told me...but I can not rememeber....and I do not know if the manufacturer ever changed between the different IRS models so I would just be guessing so I will leave the final answer to someone else who might actually know the facts.

The EMIT "K" tweeters as far as I understand use the Neodynium Magnets instead of the Senerium Cobalt magnets....I could be wrong but I do not think I am. The EMIM's on the IRS Series V's are definitely Neodynium...I know this for sure. This is in fact an issue with many IRS Series V's EMIM's. Frankly, my IRS Series III Senerium Cobalt EMIM's have held up much better over time than the newer IRS Series V Neodynium EMIM's. Here is the problem. The Neodynium magnet material is fragile and also prone to oxidation and unlike the Senerium Cobalt magnets the Neodynium magnets need to be coated (most manufacturers use Nickel). The Infinity Neodynium EMIM magnets did not have a very robust nickel coating so many of them have issues now...the nickel coating is pealing off....this makes them look bad esthetically, subjects them to weathering, and the biggest problem...the pealing Nickel and consequently the mylar tape used on the EMIM's touches the diaphrams and buzzes on many of the EMIM's on the V series. So even though they are supposedly better I in fact prefer the IRS Series III EMIM's as they are not Nickel coated and do not have this problem. I have talked to other Series V owners and this appears to be a real issue with many of them. The choice of Neodynium verus Senerium Cobalt only changes the driver efficiency and since I have plently of amplifier power I prefer the more stable Senerium Cobalt magnets to the Neodynium magnets...but this is mainly because the subcontractor Infinity used to make the Neodynium magets cheaped out on the Nickel coating...it should have been thicker and more robust and then we would not be having this problem now. So yes you can tell one EMIM from the other....look at the side of the magnet....if it has a SHINEY NICKEL COATING it is a series V Neodynium model...if the magent is dull gray..it is Senerium Cobalt and from a Series III model.

While we are on the subject....I have heard a lot of talk about RS1B EMIM's verus IRS EMIM's. Some have Scotch Tape covering the traces and some do not....in my experience they are interchangable and whether the EMIM has a Scotch Tape covered Trace or not, does not make any significant difference.

About the Neodynium EMITS. I believe the above is also true. They are Nickel Coated and shiney. Funny the coating on the EMITS seems to be superior and is not comming off like the EMIM's. The logo on the IRS Series III EMITS is like the RS1b logo....the logo on the IRS Series V "Kappa" EMIT is completely different. You can tell them apart by just looking at them. Should I post a picture of each so everyone can see the difference? Let me know and I will if asked.

Also some EMIT's have Ceramic Magnets on the back...they are larger...and thicker...so to have the same about of magnitism as the Senerium Cobalt Magnets used on the front...a magnet is a magnet...it all has to do with size and efficiency....given no size constraints...it really does not matter what they are made out of....they all do the same thing.
If it is a weaker magnet you just need more of it...hence the thicker back on the EMIT's that have ceramic magnets on the rear. Some of you most likely noticed this and wondered what was going on...here is your explanation.

On magnet alignment issue:...The modified DIPOLAR TWEETERS have the smae magnet alignment front and back...the outide magents are in one direction and the inside row is the opposite polarity...the font and back are the same...so when you reassemble the tweeters front to front as I do they work perfectly. No issues here. You can use any spare magnet to test the polarity of each row to make sure it is correct before reassembly .... if for any reason you need to make sure the polarity of each row is correct....it is a very simple thing to do...I assure you.

The EMIT Diaphragm dampening issue in my opinion comes from the fact that in the original design the rear wave needs to be 100% absorbed before it bounces back and hits the diaphragm vibrating it and even going through it....messing with the front wave....hence all the problems....my DIPOLE design eliminates the need to dampen the rear wave...it is allowed to get out freely...hence my tweeters do not have any issues like the original and sound much much much better at all frequencies, not just some. The original Strathern, the original EMIM and for that matter the original EMIT design are all symmetrical push pull designs with no inherent non-linearities. Blocking the rear wave on the EMIT's simply screws up this symmetry and why would anyone really want to do that? I just do not understand. That is why I take off the back plate and make the driver symmetrical again.

I tried to answer all your questions. Just a suggestion, in the future lets try to do the posts, one question at a time, as it will be easier to do for me and I am sure it will also be easier for you and for that matter it will be easire for everyone else to follow as well. O.K.

First off Mark thank you for sharing your knowledge and experience with us here.

Now a question for you from a comment you made

For the IRS Series III's and V's I have many Mods...but the simplest one is Tri-Amping them and getting rid of the original Infinity Active and Passive Crossovers.

On this subject what freq Xover would you suggest for the EMIMs and then the EMITS

I have a pair of RS4.5s that I thought about Tri-Amping.

What are your thoughts on the Xover used by speakers with the Watkins woofer

I do not think it can be removed from the circuit. Unless you Quad Amped them?

Thanks Jerry

goat67 said:

First off Mark thank you for sharing your knowledge and experience with us here.

Now a question for you from a comment you made

For the IRS Series III's and V's I have many Mods...but the simplest one is Tri-Amping them and getting rid of the original Infinity Active and Passive Crossovers.

On this subject what freq Xover would you suggest for the EMIMs and then the EMITS

I have a pair of RS4.5s that I thought about Tri-Amping.

What are your thoughts on the Xover used by speakers with the Watkins woofer

I do not think it can be removed from the circuit. Unless you Quad Amped them?

Thanks Jerry

Click to expand...

1. Crossover Frequencies: Woofer to Midrange 150Hz, Midrange to Tweeter 5000Hz
2. Active Crossovers: Krell KBX, Bryston 10B-LR, Yamaha D2040, if you are on a budget RANE 23B (but it is clearly not as musical as those above).
3. Watkins Woofers.....I guess I would leave it in the circuit when Bi-AMPing or TRI-Amping. It would probably continue to give you a little more bass extension than taking it out and connecting to just one of the voice coils...although you might try it each way and see what you like the best. My guess is the bass will go a little deaper with the circuit and both voice coils connected as designed...else why would they bother.
4. Quad Amping - The Yamaha D2040 will actually allow you to do this should you want to try.

Just a note: The standard Bryston crossovers are very good but only allow 6 dB/Octave, 12 dB/Ocave and 18 dB/Octave slopes. I prefer 24 dB/Octave and the only Bryston that allows you to do that is the 10B-LR model.

Mark, thanks for the informative post!!

Very interesting. Lots of information to absorb there. Ill likely reread it again.

Evan

Mark,

There's a guy trying o figure out if he wants to restore a pair of Reference Six's on a newer post. I gave him some hints for basic trouble shooting and finding Infinity info, but I know nothing about Emits. Can you look and see if you have any info for him?

MagicMarksy said:

So what kind of speakers do you have? I do not even know?

Click to expand...

Well, I’m a bit embarrassed showing my speakers to an IRS owner, but I posted about them here. The ribbons, taken from a pair of Flatline Design Model 175 hybrids, aren’t wholly true ribbons, being Kapton backed traces. However, the combination is still as light as a true foil ribbon of the same dimensions, but much more robust. The element is roughly 5/8” wide, 69” long, employs two parallel traces, the traditional ribbon accordion folding, and is attached only at the top and bottom while suspended between two columns of rare earth magnets. These elements are spec’d as being +/-3dB from 350Hz to 44kHz, so I’m using them in that function and crossing them over to a four panel set of Tympani IU bass panels, rebuilt by Magnepan twenty years ago to be equivalent to IDs.

MagicMarksy said:

I also own Apogee DIVA's and they are great too, but even they are held on the sides by tiny stabilizing points..so some people do not even consider them true ribbons...although the midrange and tweeter are closer than the Stratherns or the Infinity EMIM's or EMIT's. I agree that the STRATHERN's, etc. are best called ELECTROMAGNETIC PLANAR DRIVERS. No question about it. That is what they are....I agree 100%...they are not true ribbons.

Click to expand...

If I’m remembering correctly, it was the use of glue dots at various support points of the foil treble ribbon in the Divas that got Jason Bloom in trouble for violating Jim Winey’s (Magnepan) true ribbon tweeter patent. That seemed to have eventually been settled out of court, but rumor has it that helped bring about the end of Apogee. I’m just bothered about the whole ribbon thing due to people calling Apogees, Magnepans, and so forth “full-range ribbons” when they aren’t – an Apogee is a Blatthaler type bass panel, quasi-ribbon midrange/tweeter, and only the top models had true ribbon tweeters at the very top range.

MagicMarksy said:

In the IRS series III each woofer has two 2 Ohm voice coils and they are wired in series so each woofer is 4 Ohms....then all the woofers are in parallel....to get the 0.67 Ohm load. With the IRS Series V's they use a single 4 Ohm voice coil on each woofer all wired in parallel so the result is the same.

Click to expand...

Ah, so they aren’t actually Watkins woofers, but regular ol’ DVCs. Is there any advantage of one over the other?

MagicMarksy said:

The EMIT "K" tweeters as far as I understand use the Neodynium Magnets instead of the Senerium Cobalt magnets....I could be wrong but I do not think I am. The EMIM's on the IRS Series V's are definitely Neodynium...I know this for sure. This is in fact an issue with many IRS Series V's EMIM's. Frankly, my IRS Series III Senerium Cobalt EMIM's have held up much better over time than the newer IRS Series V Neodynium EMIM's. Here is the problem. The Neodynium magnet material is fragile and also prone to oxidation and unlike the Senerium Cobalt magnets the Neodynium magnets need to be coated (most manufacturers use Nickel). The Infinity Neodynium EMIM magnets did not have a very robust nickel coating so many of them have issues now...the nickel coating is pealing off....this makes them look bad esthetically, subjects them to weathering, and the biggest problem...the pealing Nickel and consequently the mylar tape used on the EMIM's touches the diaphrams and buzzes on many of the EMIM's on the V series. So even though they are supposedly better I in fact prefer the IRS Series III EMIM's as they are not Nickel coated and do not have this problem. I have talked to other Series V owners and this appears to be a real issue with many of them. The choice of Neodynium verus Senerium Cobalt only changes the driver efficiency and since I have plently of amplifier power I prefer the more stable Senerium Cobalt magnets to the Neodynium magnets...but this is mainly because the subcontractor Infinity used to make the Neodynium magets cheaped out on the Nickel coating...it should have been thicker and more robust and then we would not be having this problem now. So yes you can tell one EMIM from the other....look at the side of the magnet....if it has a SHINEY NICKEL COATING it is a series V Neodynium model...if the magent is dull gray..it is Senerium Cobalt and from a Series III model.

Click to expand...

Very interesting, thanks for clarifying that. Now the comment I ran across a while back complaining about the “chrome peeling off” makes sense now. Was the change over in magnet material identified by any part number change or does it all depend upon visual sighting? Seems the mix-up could cause mismatch issues due to the difference in efficiency. Speaking of which, is the ultimate power handling capabilities of the IRS III impacted compared to the IRS V due to the difference in EMIM efficiency using the same diaphragms? Is there a risk of burning up the traces in the III to reach the same peak dynamic potential of the V?

MagicMarksy said:

Should I post a picture of each so everyone can see the difference? Let me know and I will if asked.

Click to expand...

Just speaking for myself, I definitely would be interested and I’m sure such pictures could eventually prove helpful to someone else.

Also some EMIT's have Ceramic Magnets on the back...they are larger...and thicker...so to have the same about of magnitism as the Senerium Cobalt Magnets used on the front...a magnet is a magnet...it all has to do with size and efficiency....given no size constraints...it really does not matter what they are made out of....they all do the same thing.
If it is a weaker magnet you just need more of it...hence the thicker back on the EMIT's that have ceramic magnets on the rear. Some of you most likely noticed this and wondered what was going on...here is your explanation.

MagicMarksy said:

On magnet alignment issue:...The modified DIPOLAR TWEETERS have the smae magnet alignment front and back...the outide magents are in one direction and the inside row is the opposite polarity...the font and back are the same...so when you reassemble the tweeters front to front as I do they work perfectly. No issues here. You can use any spare magnet to test the polarity of each row to make sure it is correct before reassembly .... if for any reason you need to make sure the polarity of each row is correct....it is a very simple thing to do...I assure you.

The EMIT Diaphragm dampening issue in my opinion comes from the fact that in the original design the rear wave needs to be 100% absorbed before it bounces back and hits the diaphragm vibrating it and even going through it....messing with the front wave....hence all the problems....my DIPOLE design eliminates the need to dampen the rear wave...it is allowed to get out freely...hence my tweeters do not have any issues like the original and sound much much much better at all frequencies, not just some. The original Strathern, the original EMIM and for that matter the original EMIT design are all symmetrical push pull designs with no inherent non-linearities. Blocking the rear wave on the EMIT's simply screws up this symmetry and why would anyone really want to do that? I just do not understand. That is why I take off the back plate and make the driver symmetrical again.

Click to expand...

Thank you for clarifying that. Both now make sense to me. I suppose that I was seeing the EMITs as behaving in an almost acoustic suspension manner using the backwave to keep the diaphragm from developing ripples at higher frequencies, but the air mass overall in dipole operation should help that regardless. When you say “original EMIT design” are you speaking of the monopole 2x8 EMIT or the very first Daniel von Recklinghausen invented EMIT driver?

MagicMarksy said:

I tried to answer all your questions. Just a suggestion, in the future lets try to do the posts, one question at a time, as it will be easier to do for me and I am sure it will also be easier for you and for that matter it will be easire for everyone else to follow as well. O.K.

Click to expand...

Oh, but it’s hard to as it’s kind of exciting to find someone who can finally answer these questions of mine. That and I don’t want to be proclaimed a post whore for putting up a question per post. So, I’ve tried to minimize the questions this time. Honest.

Thank you very much for taking the time to answer my questions.

-JP

Samarium Cobalt EMITs

Samarium Cobalt (I checked the spelling) EMIT's:

Here is a picture of what the RS-1B EMIT's and the IRS Series III EMIT's looked like when INFINITY used SAMARIUM Cobalt Magnets

I will post more variations and more information later, but I just wanted to get started.

I have now added some more pictures of EMIT's that all used Samarium Cobalt Magnets. The silver metal EMIT's with the center spaced holes are actually the second generation of the EMIT's from the 70's and also use Samarium Cobalt magnets. The round / circular EMIT's are from some time later but also use Samarium Cobalt magnets. The ones with a CHROME faceplate are actually the very first generation of EMIT's that INFINITY had made for them by a speaker company in Leominster, Massachusetts called Peerless and these also used Samarium Cobalt magents and can be identified because the chrome finish and the off set mounting holes in the face plate are not in the center, (they were off set to the the bottom for some ease of manufacture) and the tracks for the magnets also extend all to the top, which also makes them unusual). The short 3.5 inch ones are called HALF LINE SOURCES and came in silver. At the same time Peerless also made FULL LINE SOURCE EMIT's for Infinity as well. These were 7 inches long, were always painted black, used Samarium Cobalt magnets, and were used in the famous Infinity Quantum Line Souce and Quantum Reference Standard line of speakers.

Neodymium (I checked the spelling) EMIT's

Here is a picture of what the IRS Series V EMIT's looked like when INFINITY used Neodymium Magnets.

I will post more variations and more information later, but I just wanted to get started.

I just added some more pictures of some Infinity K (Kappa) EMIT's with round faceplates from some of the later model Infinity speakers....it is my belief that these EMIT's also shared the Neodymium Magent structure at least under the front faceplate - although by this time many of INFINITY's EMIT's now used Ceramic Magnets on the rear for cost cuting purposes. Notice the logo is the same as the Neodymium model used in my IRS Series V speakers.....and since I know for sure those do use Neodymium magnets front and back....I assume the similar looking round ones at least use Neodymium on the front side as well.

Samarium Cobalt EMIM's

All the EMIM's look the same however there are several variations. Most of the variations do not matter except for the fact that the last version of the EMIM used Neodymium Magnets instead of Samarium Cobalt Magnets.

The only way I know of telling them apart is to look in at the magnets used to make the EMIM Speakers at a slight angle. Look at the color of the magnet and whether or not it has a shine to it.

The Samarium Cobalt Magnets are dull gray and look like this:

EMIM's with Neodymium Magnets

The Newest EMIM's were made with Neodymium Magnets and when you look in at a slight angle at the magnets used to make the speaker they look shiney (as they are Nickel coated) and have a CHROME LIKE SHINE TO THEM like this:

Neodynium EMIM's with Nickel Flaking Off

Neodymium Magnets are very fragile ( even more fragile than Samarium Cobalt - if you can believe that ) and also absorb moisture. To prevent these problems it is customary to coat or plate Neodymium Magnets with something and most manufactures have found NICKEL to be the optiumum materal with which to plate or coat the Neodymium Magnet. This both seals it from moisture and makes it stronger. Hense the shiney Nickel Coating.

Unfortunately the Nickel coating on the Infinity EMIM Neodymium Magnets was not very robust and has become a big problem over time. The Nickel flakes off, takes the protective mylar film protecting the EMIM diaphragm from shorting out against the magnet with it, and furthermore often touches the diaphragm in places causing the diaphragms to buzz, especially during loud passages when there is a lot of diaphragm excersion.

Here are some pictures of some BRAND NEW NEVER USED NEVER INSTALLED INFINITY EMIM's that have the Nickel coating on the magnets flaking and peeling. These EMIM's were in a box unused for 20 years and this still happened to them. So it is not only the EMIM's out there in the field that have problems, it is also the spares sitting in boxes never used...just deteriorating over time.

Note not all Neodymium EMIM's have this problem. So some are still O.K. as shown in my previous post. But Many do and so here is how to recognise them.

Frankly this is one reason I prefer the older Samarium Cobalt EMIM's as they never have this problem. So do not be sad if you find you thought you had EMIM's with Neodymium Magnets only to find your EMIM's really have Samarium Cobalt magnets. You might consider yourself lucky.

Anyway here are some pictures of some bad ones. I hope they help.

A Work In Progress

LAST UPDATED 9/5/2007:

Currently a work in progress at my home in Clarksville, Tn.

6 foot tall line source - Construction 3/4 Inch Solid Natural Red Oak
Per Side:
Midrange = 60 inch Carver Ribbon
Tweeters = 6 Infinity Special Full Line Source Dipole EMIT's
and
5 Infinity Special Half Line Source Dipole EMIT's
alternating.

Notice: All the EMIT's have been rebuilt using my special Dipole process.
I alternated Full Line Source EMIT's with Half Line Source EMIT's
Each Full Line Source EMIT is about 5 Ohms
So 3 in Series makes 15 Ohms
Each Half Line Source EMIT is about 3 Ohms
So 5 in Series makes 15 Ohms
I will connect up the EMIT's in a series / parallel array so the tweeter array will
turn out to be about 5 Ohms
The Carver 60 inch ribbon is also about 5 Ohms

Over the next few weeks I will be wiring them up, and giving them a listen for the first time.
I do, however, know what to expect.
They should be fantastic.
Let's hope I am right.
They have been a lot of work and with all the tweeters needed to build these...relatively expensive.
Since each DIPOLE TWEETER actually took 2 tweeters to make, these speakers consumed 24 FULL LINE SOURCE EMIT's and 20 HALF LINE SOURCE EMIT's in their construction process.

Contact me if you like, anytime, for questions or just to chat.
MichaelAlanMarks@aol.com

Thank you much for the pictures. They're very informative and I think should be put into their own thread to avoid their being overlooked.

Regarding the peeling nickel coating, does any moisture absorption affect performance? If so, have you found any way to reseal the neodymium magnets to protect them after the plating flakes off or must the magnets be replaced?

Interesting project there with the Carver and Infinity combination. I'm assuming they're inspired by the QRS, IRS, and possibly Nudell's Genesis line with the BG midrange elements? They too might be worth their own thread. Are you going to use Tympani bass panels for the low end or go with conventional Rice-Kellogg type drivers in a monopole or dipole arrangement?

- JP

Nickel Plated Neodymium Magnets and Threads

Charivari said:

Thank you much for the pictures. They're very informative and I think should be put into their own thread to avoid their being overlooked.

Regarding the peeling nickel coating, does any moisture absorption affect performance? If so, have you found any way to reseal the neodymium magnets to protect them after the plating flakes off or must the magnets be replaced?

Interesting project there with the Carver and Infinity combination. I'm assuming they're inspired by the QRS, IRS, and possibly Nudell's Genesis line with the BG midrange elements? They too might be worth their own thread. Are you going to use Tympani bass panels for the low end or go with conventional Rice-Kellogg type drivers in a monopole or dipole arrangement?

- JP

Click to expand...

I would love new STICKY threads for each of these subjects for all to see.

My suggestion would be:

* Infinity EMIM's (Observations, Repairs and Modifications)
* Infinity EMIT's (Observations, Repairs and Modifications)
* Infinity QRS (inspired us to build these speakers)
* Infinity RS-1b (Observations, Repairs and Modifications)
* Infinity IRS Series III and Series V (Observations, Repairs and Modifications)

We could do others but this would cover 98% of my posts.

As for the Neodymium Magents that have the nickel coating that is flaking off...the only real honest to goodness solution...is to replace them.
A short term solution is to BLOW OFF THE LOOSE DEBRIS with an AIR GUN or can of compressed air. This gets rid of some of the loose debris and decreases buzzing but it is only a temporary fix and does nothing to the underlying problem.
One could take apart the EMIM's and effect a more permenent solution (take the magents off, clean them, have them replated in nickel, and remount them). This is a lot of work and I have not does this.
Short of that one could replace all the magnets...so far I have not found the exact correct size so I have not been able to do this either.

One might take the EMIM's apart, clean the magnet's as best as possible and paint them with CHROME MODEL PAINT. This would be better than nothing, but again I have not done this.
Eventually the magnets should absorb moisture and deteriate further but no one has reported this happening yet.
I know of one person that repaced ALL HIS EMIM MAGNETS. They were a little thicker so he had some small spacer plates made to take up the slack. His solution worked fine, but I was hoping for a simpler more elegant solution....finding a population of the exact same size Neodymium magents would be nice....but I have not been able to find them yet.
I did buy some magnets, but they were just slightly too big, so I returned them.
Never did get my money back though. They kept it.

As far a woofers go. I like the Audio Research / Magnaplanar Tympani 1D's and these new speakers with the CARVER 60" ribbons were made with them in mind. I also do have some lying around. Two sets I think. I guess you are starting to be able to read my mind...or see where I am going with these things. A good alternative is the INFINITY SSW-210 and SSW-212 line as well. These are also easy to find and have a relatively good price / performance ratio. Don't you agree?

I also use, and have used, the Bohlenger Graebner ribbons too.....only the 75 inch ones though.....these are good as well....Genesis switched to them from the CARVER 60" ribbons mainly because the CARVER 60" ribbons were no longer being manufactured and the BG 75" ribbons are now readily available. Whether or not they are better....personally...I like big long ribbons (pseudo ribbons - electromagnetic planar speakers) and since these BG's are 75" as opposed to CARVER's 60", yes they might even be better....I also have some of those lying around the house...I have used them previously...and I will obviously use them again as well.

Remember, all these pseudo-ribbons go well up into the high frequencies, and the use of tweeters is really optional.....mainly to get better dispersion characteristics way up there at the high end....but look at a huge financial expendature....look at all the tweeters I used....and with my DIPOLE design I need two original EMIT tweeters to make just one DIPOLE EMIT...think about all the money.....most people on a budget would not do this...this is for the person with no budgetory constraints....obviously.

More later,
Got to go now.

Michael

MagicMarksy said:

...One could take apart the EMIM's and effect a more permenent solution (take the magents off, clean them, have them replated in nickel, and remount them). This is a lot of work and I have not does this...

Click to expand...

Can't the magnets just be wire-brushed and then painted? Many magnets are painted and the paint doesn't seem to lessen the magnetic field.

Painting verus Nickel Plating the Problem Magnets

Yes....I mentioned this...but do not think it would really fix the main issue.
The magnets are very difficult to clean and although painting them ( I would use CHROME MODEL PAINT [ I actually I went to Hobby Lobby 3 months ago and bought 5 little bottles of this stuff but still have never used it.] ) would be better than nothing..the real solution requires replacing the magents or having them nickel coated all over again.

From my last post:

"One might take the EMIM's apart, clean the magnet's as best as possible and paint them with CHROME MODEL PAINT. This would be better than nothing, but again I have not done this."


Michael