I just picked up a set of Ess Elite tweeters. They look like a set of Amt tweeters mounted in wooden enclosures as a tweeter only speaker add on. Does anyone know anything about these as far as was there a few types of heil amt style tweeters and what was changed if there are? Also when were they made. I will post some pics shortly. Thanks, steve
here's one pic
here's another pic of the front
More than you ever wanted to know about your AMT's
I think I can tell you much about your Heils, even though I have never beheld that particular model in person.
That is to say I've not seen that entire unit/enclosure set. I've seen many, many of the raw AMT drivers in your second photo. I've even put a few of those puppies back together from a suprisingly huge array of diassembled parts--no simple chore! (Each one of those "lines" on the focus plates are a speperate peice of metal! Not to mention that the huge magnets on either side of the diaphragm are forced together south pole to south pole!... Talk about smashed fingers!)
What you basically have, for all intents and purposes, is the original AMT-1 "Great Heil" driver (I guess "great" means "the big one"). The AMT driver itself only has a part number (of which escapes me at the moment) updated versions of the "G-H" simply replace the previous one and assume the same old part #, but the different circa Great Hiels are usually referenced by the model # of the ESS flagship speaker system that they first appear in, yours being the AMT-1.
The AMT-1 Great Heil is identifiable by the plastic "box" enclosing the entire top and bottom of the unit. This was modified on the following model by reshaping the "box" enclosure to only cover the magnet structure, probably to minimize early reflections, (thus, if you were looking down, from above, at the "AMT-1b" unit, you'd see a sideways "hour glass" shape instead of a "box").
After the "1b", the entire magnet structure was redesigned; The intricate silver magnetic focus plate arrays were replaced by a single piece magnet/plate that had the focusing "teeth" already milled into it. It made for a lighter weight unit, yet it had the same "BI" (m-flux field density) at the diaphragm. Since then (about 1977), the magnet structure hasn't changed one bit, even to this day!
So, with any "Great Heil"; AMT-1, 1b, 1c, 1d, 1e, 3, 4, the new $12k- PS-450, or the bla-bla-bla, the magnetic field driving the thing is all the same (really, really, strong). The big difference is in the diaphragm.
Now the diaphragm design itself has changed quite a few times. This is important to know, because the original production AMT-1 diaphragms were very delicate, prone to damage, and have a fairly limited life span. (Actually, ESS refined the design mid-production, and issued replacements to many customers.) Even with all the improvements, the diaphragms do not last forever. Until recently, it was not uncommon for ESS owners to replace thier diaphragms every year or so. Thus it is very liklely you have newer diaphragms in your units. If you plan to do anything other than just use them as they are, you'll need to know what diaphragm you have, as therein lies the technical specs.
Now this might seem a pain, but the beauty of all this bother is, when you replace the diaphragms, you get the latest refinement. It's like getting the latest software updates! (Unfortunatly, this little necessity has now turned out to be both good and bad, but I'll get to that later.)
Here is all you'll need to be able to identify the correct part and conduct an informed search : For all the Heils out there, there are only five different diaphragm models...One, is about half the size of yours, and suspended in cardboard, another is that same half size, and suspended in a plastic frame. Yet another is wider than the Great heail diaphragm, but not as tall, (it is extremely, extremely rare). Finally there is one that is as wide, but slightly shorter than your ideal diaphragm, it will work fine in your units if it comes to that. Then there is the correct diaphragm: ESS part# 689-1107. (Can't tell you how many times I've orderd that part.)
If your going to include your new AMT's in a project, I recommend that you start off with a new pair of diaphragms. Unless, a) you have tested the ones you have, and they seem fine, or b) you just can't find the damn things anywhere, which is more and more, getting to be the case. I recommend replacement for a couple of reasons:
First, the new 689-1107, is quite possibly the last diaphragm you'll ever need to get. Time will tell, but they seem to be much, more resilliant than previous designs. The new membrane material holds its shape much more readily, yet it can still respond quickly to signal, and the mass is still very low. They are a clearish yellow color, that is the only identifiable distinction from older designs. ESS, unfortunatly, does not update the part number along with the part.
Second, this may very well be your last chance to get new diaphragms. ESS recently moved from Sacramento, to Germany! Every domestic source that I knew of for getting the part has stopped stocking it. It actually took me two months to even find ESS in Germany. Further, the price for the part has increased dramatically (as has the price for ESS speaker systems). If you do a seach on DIY Forums under my name (matt28sr) you'll see a thread on this very subject, and possibly a source to get the part in Germany. Also, here is ESS:
Languages Spoken: English, French, German
Gonzenheimer Str. 4
Frankfurt am Main 60437
Phone Number: 49-69-503570 Fax: 49-69-504733
Company Email: email@example.com
(Okay...thats part one...see the next post for part two)...
TMI ON AMTS BY ESS!
part two.... (who knew you couldn't exceed 1000 words...)
If you do get diaphragms from Germany, as far as I can tell, the specs of your Heil will change significantly, and the crossover in that system will probably no longer be adiquate (provided the stated impeadance of the system is either 6 or 8 ohms). This link will show you the specs of the German diaphragm:
It's all in German. If you need english, first click the button that says "mehr infos" next to the picture of the current "Great Heil". Once at the new page, scroll down until you see a little British flag on the left, and click it. You'll have the specs for the Heil with a 4 ohm version of the new diaphragm (which is appearently the only one they make in Germany).
In the meantime, take a close look at the diaphragms you have. Are they clear, cloudy, black, or yellow? If they are clear, do they appear to have a fine mesh "netting" that covers the pleats of the diaphragm, or are the pleats floating free? If it appears to have the mesh netting, then see if you can see the tracings of the voice "coil" running up and down the sides of the pleats...Are they single silver strips, or are there two, slightly waving, black tracings? The latter design is more sturdy.
If they are black, get new ones. I have never personally heard the black teflon diaphragms, but I have heard many a horror story, they were a failed experiment.
If they are clear / silver, with free floating pleats: These are the ones to treat delicately. They sound wonderful when everything is just right, but they are easily knocked out of balance. They don't have a lot of heat tolerence (Heils generate a unique heat as a result of the accelerated sound waves. In fact you can place a rubber band on the surface of an operating diaphragm, and it will melt in minuets!) To test for wear, try playing a recording with a long sustaining female voice, or maybe some long sustaining brass inst.s; if you hear a bazooka-like rattle during the sustained passages, they need to be replaced.
If the diaphragms are mesh-netted, clear or cloudy, with black voice coil tracings, then these are the next best to new. If they pass your listening test, they'll probably be fine for some time to come.
If they are yellow, then your in luck! They're probably the American made (8 ohm) version of the new diaphram and will last for a good long time (many years I'd bet). Plus the crosover that came with your system will continue to work fine.
To be sure of your AMTs impeadance, take a dc resistance with the crossover disconnected. If the reading is 5.6 ohms, you have an 8 ohm unit. A 4 ohm unit will have a DC resistance of 3.4 Ohm.
So at long last, here are some specs for an 8 ohm Great Heil. These most likley will apply to your AMT-1(s):
Back in the day (when your AMTs were built) ESS was crossing them over at 800Hz high-pass! First, at 12dB/oct, then later at 18dB/oct. The exception was the "Rock Monitor" Model. For obvious reasons, the crossover point was around 1200Hz.
With the crossover operating, the rated continuous power toterance was 300 watts!
Resonance is around 600-650hz depending on the diaphragm type.
The impeadance is pretty much ruler flat with a very slight rise at the resonance freq.
Between the power handling and the flat impeadance, it's no wonder it was common practice to cross them over so low. You can actually play them down 'til the frequency is so low the pleats slap agaist each other with a "pop"! (That happens around 200-300hz). It doesn't seem to do any major damage (at reasonable volume levels), it just sounds awful.
Now days, I see ESS crossing them over at 1700Hz, though I do not know the slope. I also see a much more conservative power rating published too.
Finally, if you have never worked with Heils, you are going to have fun. They are amazing, even with worn out diaphragms they'll drop your jaw! The trick is to pair them with a FAST FAST FAST midbass, and a very efficient one at that. I always use two midbass drivers, and a seperate subwoofer. Give the LF driver every advantage you can; minimal delay and Q in the crossover, a lower impeadance than the AMT, tilt the baffle up a bit if you can, and be sure to place the Heil in physical phase with the LF driver voice coils. Putting an l-pad on the Hiels is a good idea too.
You see, Hiels respond to the source signal around 400% more quickly than a dynamic driver can. They are the only driver in the world that can correctly reproduce a square wave! They also have about the same radiating surface area as a 12" woofer (unfold the pleats!), Plus they have a 4.3:1 compression ratio! That means if the diaphrgm moves 1" the equivilent mass of air moves 4.3"!! Your at a marked disadvantace trying to find anything that can begin to preform like that for the low frequencies. But it is possible to make a pretty wonderful sounding pairing, if not the perfect match.
Finally; there is a new tecnology that may actually make possible the closest thing there will probably ever be to a full range AMT speaker system!..It could be that the Tymphoney LAT design will finally produce a really ideal LF driver match for the AMT. We'll have to see; first they must make available a DIY model that will operate to 2 or 3kHz. This is probably not a major priority for them...But what the hey, I'm willing to wait. After all, its been almost 40 years since the first prototype AMTs appeared. What's another few years?!
I hope this answered your questions. If I can be of any othe help, just let me know.
From your postings I get the impression that you have done a couple of these projects and I would love to pick your brain about undertaking such a effort. Considering the Aurum Cantus AC200MK 2 8 inch Woofer with 2 per cab in a bi-pole configuration but still playing with the box design (using WinISD beta). I'm new to the DIY scene but spent my entire professional life repairing and installing electronic systems (stereos to Radars) and know my way around a wood shop.
I would very much appreciate input and ideas from anyone interested.
Great info on the AMT's Matt, just what I was looking for for a long time, a good summary of the different diaphragm types.
I have owned the same AMT models as in the pictures Steve posted a few years ago but sold them because they sounded pretty bad with terrible harsh top-end. Always had the feeling that they could be much better than that, I guess they where worn out to much to produce a decent sound.
Later on I have bought a couple of the older versions of the smaller AMT and they sounded much much better and I still have them in use today after spending literally thousends of euro's on tweeters. The best thing that I like about them is that they detailed as a good ribbon driver but with more "guts and balls" and they never get on my nerves like most tweeters do from time to time. They are very forgiving to bad recordings and will sound very detailed even then when most other tweeters become harsch or nervous sounding. Switching back to the AMT's always feels like a relief.
So Steve, get yourself a pair of replacement diaphragms right away when you have the feeling that they do not sound as good as your other tweeters, they are worth it.
I appreciate the responses and have learned a few things. But what is an L-pad? I measured the resistance of the diaphragms and came up with 5.1 ohm on my dvom. So I assume they are 8 ohms? If I got a pair of german diaphragms that are 4 ohms would I have to do something to the crossover to make it work with a 4 ohm diaphram? If so would it be an easy fix. The crossover in the ESS ELITE box has a switch for 1khz or 5khz crosover point. My setup is a pair of Klipsch rf3-II's with the tweeter disconnected and input to the ess tweeters comes right off the power input on the klipsch. The crossover point to the tweeter on the klipsch is 1975khz. Thats really close to the 1khz option on the ess box. They sound amazing the way they are right now. I have the switch set at 1khz. The tweeters do have the full size plastic box. The diaphragms are clear with no black or mesh on them. I will be getting a pair of the yellow ones but I do not want to destroy any part of the crossover but will modify it if i have to-to use the 4 ohm diaphragms. Anyone ever had to do something like this? I am thinking about taking one of the 8" woofers out and installing a fast midbass driver. Any suggestions on a midbass driver and would it be smart to just get a new crossover for the klipsch to work with a midbass driver and cut off at 1khz for the tweeter? Also has anyone found a place in the USA supplying the diaphragms yet? firstname.lastname@example.org
ESS Heil and Klipsch RF-3 II
You might be able to find some answers about your RF-3 II's at http://forums.klipsch.com. If you type in RF-3 II into the search terms it should take you to an area about those speakers, x-overs, etc. I'm not sure of the spec's on those Klipsch drivers but they meet your needs "as is" - and heck - if they are sounding good already then you can take your time and look around a bit.
I just checked at PE and no joy on any diaphragms for the ESS AMT's there (at least not yet). So far the only source that might be available is the one in Germany that was discussed a couple of post back.
I'm looking at doing a box for my Heils and have been looking at the AURUM CANTUS AC-200MK2 8" CARBON FIBER SANDWICH WOOFER available at PE and some other places.
I'm going with active amps and active x-overs tho and at this point the BEHRINGER DCX2496 and some SKA's are on my short list.
Hope this helps
You may not need to sweat the tweeter crossover point, as in the worst case, the AMT is just overlapping the current midrange in the Klipsch by around 1KHz. As matt28sr pointed out (great dissertation by the way, sir) the original crossovers on the AMT-1 series were set for 800 to 1200 Hz with the AMT handling both the mid range and tweeter duties. If the Klipsch crossover is sending everything above 1975Hz up the line to the Elites that you've got currently set to start at 1000Hz, then I'd think you'd be fine as anything below that probably isn't appearing at the AMT anyway.
I have a pair of original AMT-1a floor towers, plus a spare pair of AMT-1b Great Heils. I have also been toying with some sort of cabinet design that utilizes the spare Heils. I've also thought about modifying the original 1a cabinets to accept a Morel MDM-55, a 55mm Neodymium dome midrange with very nice specs and good reviews (~$82.00) and just changing the insides to a 3-way crossover akin to the AMT-3 units where the AMT would be set to kick in around 3000Hz.
The other thing that's caught my attention in the DIY arena are the woofers (and mids) from Hemp Acoustics (yup, the cones are actually made from 100% hemp fibers) that look to give the Fostexs a nice run for their money in the SPL vs Frequency department, plus the sound has been hearlded as really natural compared to other available materials. http://www.e-speakers.com/products/hemp-acoustics.htm
With the FR8.0 at 94bB I'm thinking that they should pair nicely with the 93dB Great Heils and 90.5 dB Morels (BTW, Hemp just introduced a whopping 25" subwoofer too. :bigeyes: )
As for AMT diaphragms in the US, I sent Simply Speakers an email about replacements being carried by Audio International over in Germany as matt28sr had discovered, so perhaps we AMT owners can hope they'll contact them and make arrangements to start carrying the newer diaphragms over here.
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