Ribbon midrange pros and cons

Ribbon tweeters are fairly common on some high end speakers. ...they sound great.....can anyone tell me why ribbon midranges are hardly ever used by some of the best speaker companies. ..what are the pros and cons? 
Do you mean a true ribbon, or an AMT like, or a planar magnetic?

Give some examples of a speaker with such a beastie. :)

Well, the biggest con is they really aren't all that great.

Ribbons are very fast, but flexible. So good at frequencies so high your dog can't even hear them, because those don't call for moving much volume. Go even a little lower though into the midrange and now the air they have to move is too much for their soft design.

Ribbons also have hard to drive low impedance, which calls for a transformer, which then the transformer becomes a factor.

I honestly never understood why anyone would use them, especially since I never heard a speaker with a ribbon that sounded any good to me. Actually now that I think about it one of the worst systems I ever heard had a pair of Carver's Amazing Speakers which feature a great big long ribbon that I think tried to get around the physics of low frequency by making the ribbon 5 feet long. Or something like that. Plenty of other reasons that system was so awful, can't put it all on the ribbon. But still....

Give some examples of a speaker with such a beastie. :) 

Red Rose Revelation
Infinity had the EMIT tweeter and EMIM mid back in the day; both ribbon diaphragm design. Innovative at the time but not a big hit.
Infinity had the EMIT tweeter and EMIM mid back in the day; both ribbon diaphragm design. Innovative at the time but not a big hit.
Some of those speaker systems have withstood the test of time, such as the RS-1 and IRS Beta systems. But they aren't ribbons - they are planar drivers.
Wikipedia describes the Infinity emit and emim units as "quasi ribbon" units so it would seem I was quasi correct. 

Don't confuse tweeters like Infinity, Amt, ect ect for true ribbon tweeters like on Magneplanars, Apogees ect ect 
True ribbons are the closest you will get to ESL's, and ESL's are the closest you will get to Plasma. (it's all about mass "diaphragm" weight)

Cheers George
RAAL makes ribbon tweeters  
Companies like GoldenEar use AMT tweeters, they look similar but are different tech.  
The RAAL tweeters are some of the best on the market, but they don’t make any midranges, and I don’t think I have ever seen a ribbon midrange, probably because those frequencies require much more air movement. 
Not really sure why we refer to some form of Ribbons as not true ribbons, whether its an open (dipole)design or backed (which causes cancellation) or a folded ribbon (AMT), it seems to me that it is still a ribbon.  As far as strengths and weaknesses, I believe that many have been addressed. One which can be both is speed.  Ribbons are fast, There have been several companies that produced ribbon speakers that when used with a tradional cone woofer, mid woofer or sub,  had issues with the speed of the ribbon matching the speed of the cone driver.  Next,  it was mentioned that a ribbon without some sort of transformer was a problem. The amplifier sees the ribbon with such a low resistance that it is basically an open load and will cause most amplifiers to have a real fit. Never hook a ribbon driver to an amplifer without a crossover in front of it. Directivity is effected by ribbon length,  so combining directivity with panels that are dipoles, it is not always easy to get optimum set up in many rooms. Ribbons done right can be a revealing experience.  I do recommend everyone to sit in front of some very good ribbons at some time in their audiophile walk.  They are not for everyone, but when done right and well set up, they can be a great experience. 
I hope this helps, 
Correct, Raal tweeters are fantastic and the sound coming out is also dependant on the overall speaker design. Just cannot say all ribbons sound bad as a blanket statement. Just not true. Robert of Acoustic Zen incorporates a ribbon in his Crescendo speakers that sound wonderful. Again, the complete design is key! Tonian Labs also uses ribbons and they are some of the most musical speakers I have listened to. 
Thank you guys for all the responses. .those explanations were on the same lines as l was thinking ...l was particularly thinking of the infinity Beta ,the Epsilon and the new speakers PS Audio is working on...Paul says hes working on a 120 db. Ribbon midrange .l just dont see other manufacturers using these types of midranges and wondering why.l an going to Expona this weekend in Chicago to listen to some great systems. ..lm sure to be impressed. ...
Adam Audio has ribbon mids . Don't know if its a pro or con . I own the Tensor Gamma version . It is probably the closest in sound to my King Sound King electrotat speaker I have come across in detail , speed and tone .
PS Audio was working on an AMT midrange, but was unhappy with the sound. At AXPONA, they will be using a Bohlender Graebener Neo10 planer magnetic driver.

There is a lot of inaccuracy bandied about when talking about ribbon transducers. A ribbon is a piece of very thin corrugated foil suspended in a magnetic field. They are not planar magnetic drivers (the AMT is a folded planar magnetic driver, and the Infinity EMITs and EMIMs were planar magnetics). And although 1930s era ribbon microphones did require matching transformers, modern ribbon drivers, i.e. as used in Apogee speakers, have a long enough ribbon that their DC resistance is near 4 ohms and does not require a transformer. I’m uncertain what Magnepan uses, but my guess is long, thin, planar magnetic drivers. (Though the new LRS may use ribbons - but if the conductor is bonded to a membrane, it isn’t a ribbon).
The true test is in the listening.  I own a pair of 3.6 Maggies, that aing when driven by McIntosh MC501s via a tube preamp.

Yes, they open up with sufficient power / current.  There is a reason that many are fans of this configuration.  Ask Elizabeth how her 20.7s sound and image.

Listen to a well set up pair driven properly and you perspective will most likely shift.

If you want the best ribbons, Selah Audio. :)

I've interacted with the designer at Raal, absolutely brilliant guy.

My experience is just, even top notch ribbons have their own sound. If they are what you like, buy them! :)

RAAL ribbons are great and the 70-20 can be crossed over as low as 1800hz in a 2-way. However, compared to a dome with good excursion they lack some dynamic punch in lower mids, so generally they are better off in a 3-way because of this.
I like listened to speakers such as the Martin Logan Motion 60 towers and the Dali towers and I thought ribbon tweeters sounded bright but too bright.  A friend warned me about ear fatigue and I am glad I listened to him.  This said, I wonder what speakers sounds best priced between $6,000 and $9,000.?
None of you have heard of the long-discontinued Apogee full range ribbon loudspeakers?! Three way, all three drivers (bass, midrange, tweeter) being true, pure ribbons. They remain the all-time favorite speakers of some. Very hard to drive---their impedance dropped below 1 ohm, and were very insensitive/inefficient, and were therefore commonly paired with Krell amps. And they were pretty expensive.
Its funny that you mention the Apogee ribbons. ..back in the 80's my best friends father had a machine shop and he was making the framework for the Apogee ribbon speakers. He had two sets in his house driven by Krell amps and JBL 18 in.subs..That was our after school party system for many years. ....sorry to say his wifes cats destroyed them and about 20 years later he gave me both sets....they were so big it took two men just to move the tweeter column.They were easily the size of a front house door .l posted them on Audiogon many years ago and a guy drove from New York to Indiana in a rental truck to buy them...l had no interest in restoring them...Anyway the sound they produced was very open and airy with a big sound stage....and very detailed. ....but they lacked that dynamic punch you get from a traditional cone type speaker so l had no interest in them....
I have a pair of Infinity epsilons that use Infinity’s 2nd generation High energy planar EMIT tweeters, High energy EMIM midranges and High energy L-EMIM mid bass drivers.

These 2nd generation push/pull design drivers have greater dynamic range do to the much improved magnetic circuits, they play 12 db louder with a smoother response and a wider bandwidth while having less distortion and coloration than infinity’s original planar drivers.

While I would say these newer Infinity planar drivers are much improved over other modern day planar driver speakers that I have heard, they still are not quite as dynamic as most cones and domes but they do so many other things better than most cones and domes that once you have a listen to them with really good recordings and electronics it will be hard to go back to cones again, I have been listening to planar speakers for over 25 years and have yet to hear a cone speaker that can match their sound quality in other than dynamics.

So I have a question, did the OP mean to ask about ribbon _midrange_ drivers?? That's why I asked about specific speakers, and especially current models.

I know of a lot fewer midrange, true ribbons than I do say, a midrange AMT or planar magnetic.

I’m uncertain what Magnepan uses, but my guess is long, thin, planar magnetic drivers. (Though the new LRS may use ribbons - but if the conductor is bonded to a membrane, it isn’t a ribbon).
I did some research and Magnepan makes "true ribbons" (some of their tweeters), as well as "quasi ribbons" really planar magnetics.

I think the OP was unclear, and seemed to group all flat rectangular drivers as "ribbons." He mentioned the forthcoming PS Audio AN speakers, which are using planar magnetics (or maybe AMTs) for their midrange.
Having owned Apogee Divas for 16 years I feel a bit qualified to talk about this. There are very few true ribbon speakers on the market. Mostly you see small ribbon tweeters and for many of the you can get replacement ribbons. Magnepan has a tweeter ribbon replacement program. They will send you a new set of tweeters and you send them the old ones back. All for a minimal fee. They rebuild the old ones and give then to someone else. The magnet structures are very hard to damage and they essentially will last for centuries. All ribbons are very fragile. If your wife tries to clean the speaker grill cloth with a vacuum they will suck the ribbon right out of the speaker. Magnepan uses what they call a quasi ribbon for the mid range driver which is a mylar diaphragm with wires in it which is more like a planar magnetic driver. Much tougher. The Diva used pure ribbon drivers throughout and under the right circumstances they sounded wonderful. But, there were problems. It was hard to get them up to 100 db even with subwoofers.
The ribbons stretched over time. The ribbons were very easy to damage physically. My nephew kicked one of my woofer ribbons at the age of two putting a big dent in it. As soon as Apogee went under I sold them and put my old Acoustats back in service eventually solving all the issues I had with them. Good electrostatics are immortal. In order to hurt the Acoustats I would have to drive a stake through them and boy do they go loud. Magnepan tweeters are the most durable ribbons I know of and boy are they great tweeters I tried to buy a set from Magnepan and they would not sell them. I also think Magnepan makes the best dipole planar loudspeakers that are not electrostatic and they are absolutely a fabulous value. It is also a great company to deal with. 
Over all I think you are much safer with dome tweeters then going for ribbons with point source speakers. Once you go linear array then you can not beat Magnepan's tweeter until you go electrostatic. m

I have a pair of the Magneplanar Tympani T-IVa, which have the great Magnepan ribbon tweeter. I also have the ridiculously-overlooked and under-appreciated (not by all; they got a great review in TAS, and VPI's Harry Weisfeld loves them) Eminent Technology LFT-8b, which has a ribbon tweeter and magnetic-planar midrange (180Hz-10kHz, with no crossover!), with push-pull magnetic structure. Best deal in planar loudspeakers, $2499/pr.
Dear @bdp24  : The only model in the Apogee catalog that goes below 1 ohm was the Scintilla and paired with the Classé DR 3-VHC ( 25 watts pure class A with over a headroom of 6dbs. A true horse/voltaje power. ) performs just great

I owned that amp and had for a while the Scintilla ( from a close friend distributor . ) as a demo pair.

Thanks @rauliruegas for that info. I think I’m one of the few planar loudspeaker lovers who never heard a pair of Apogees. For some reason they didn’t seem to be big on the West Coast; I never saw a pair in any California hi-fi shop, Northern or Southern.

Those are AMTs not ribbons.


The BG Neo planar midranges are real good, Philharmonic uses the Neo 8 in their tower speaker. http://www.philharmonicaudio.com/phil3.html

I also saw it being used in a speaker when I went to the Florida Audio Expo.

No clue on distortion, but it’s imaging/soundstage is excellent for the price, very glad that PS Audio is considering them, it looks like they are using the Fountek NeoCD3 for their tweeters, which is also a good choice, obviously not as good as say a RAAL 70-10D, but it is of course around 1/5 the price.

EDIT: Going off this image, it looks like the tower is using this Dayton tweeter, which is still efficient and has good imaging/soundstage, but I guess/hope it’s a placeholder and not the final choice, as it would be odd to use a different tweeter for the bookshelf and tower (you an see the bookshelf in the background with the Fountek tweeter). I also can only see the bookshelf woofer as being a KRK or HiVi one, as hardly anyone is making yellow woofers and I doubt Paul requested for the cone to be yellow.
I live just 40 miles from where Apogee was.
I suspect they were not prevalent on the west coast because they were very expensive to ship and very fragile which would have added a lot to the cost.
Scintillas destroyed more amplifiers than any other speaker I know of which interestingly enough made them a very popular cult item. They were ok but not near as sonically correct as the Divas. If you did not listen above 95 dB the Divas were fabulous. Their real talent was in the mid bass region. Upright acoustic basses were unbelievably real on these speakers. Only electrostats are capable of that kind of realism. Magnepans come very close. 
All planar dipole speakers have significant acoustic advantages over drivers in a box. The only place they stumble is in the very low bass. A subwoofer array fixes that,
May have much to do with production costs and logistics for the mass market. Being an Apogee owner (Duetta Signature and Scintilla models) there is a reason (in earlier post)  why someone drove from Indiana to NY to get them. Yes they can be challenging to set up, yes they are obtrusive to some and yes the Scintilla’s are tough to drive. Once set up correctly they are quite remarkable top to bottom without subs, IMO. And just to strike some balance i do enjoy my old LaScala’s and my buddy’s Golden Ear Triton reference speakers. So many great and unique choices. But they are no Apogee...:). 

With the DSP sub/servo stuff today it will be interesting to hear how the new PS Audio AN’s sound with midrange ribbons. I am sure a great outcome.
Over the years I have owned Acoustats (3 panel model) then switched to ribbons, (Apogee Full Range) kept those for a couple of years, used Krell amplification as a logical choice, after which I upgraded to the Apogee Grand, a speaker way ahead of it's time, and for the few Grands still playing at this very moment, they will still be top contenders. I had to sell mine due to moving house, and the new house not suitable for these rather big speakers. After some years moved to a bigger house again, and currently again using ribbons, well hybrids. (Gryphon Pendragons). I have heard many speakers, but will stick with the hybrid combination. For those who believe that ribbons (Hybrids) can't be enjoyable, feel free to visit, it may change your opinion....
 I’m surprised that nobody mentioned Strathearns that address a lot of the problems mentioned. They are great from around 400 Hz on up.  There is no need for a transformer if you put a couple of resistors in line with the amp.
The old Heil AMT1 speakers had ribbon drivers in a semi-horn bidirectional enclosure that were pretty awesome sounding in the ribbons range, which reached down into the midrange.
A slight correction to Raul's comments.  The  Classé DR 3-VHC is not a 25 watts/ch amp, it is spec'd at 45 watts/ch in pure class A.  The smaller DR 2 and DR 3 were rated at 25 watts/ch.  They could all be bridged and basically quadruple their power while remaining in pure class A.  All 3 amps would be able to drive the Scintillas (and they would deliver full power in class A).

Regarding ribbon midranges, the top model Genesis speakers designed by the late Arnie Nudell used B-G ribbons that shared many similarities to the the ribbon used by Bob Carver in the Amazing Platinum Speakers (I think Carver used Kapton, and B-G used Mylar).  Those ribbons are extremely easy to drive (they are basically a 6 ohm resistive load), and excellent sounding; however, there are no longer produced so they are no longer a feasible option for speaker manufacturers to consider.