New ESS Heil Speakers!!

rocky5656 said:

I didnt mind at all my AMT Classics, Heil on top with a 10 inch woof to the front and 10 inch woof with no voice coil on the rear. Better than 90% of the vintage stuff out there. But of course, because of the Heil's fantastic range. Corner placement was key for me.

Most classic rock likes the mids toned down a bit, ie the eq "rock and roll smile". Jazz and classical a different story.

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Great point Rocky-the Classic were a rock and roll speaker formost-but as you mention the drawbacks of the design are realitively small compared to alot of speakers of the same vintage, and even alot of newer stuff.
They have a different voice than the AMT3, but a easy speaker to listen to when upgraded.
Lot's of people have bought and enjoyed them over many years-some pretty loyal Heil addicts-says a lot IMHO.
To me, the overall strength of the design lends itself very well to upgrading, especially with the case of the woofer.
Carefully choosing source componets can also minimize the problem with classical or jazz material on the larger 2 ways.
The AMT3 is the tops, but the classic AMT is still a very good speaker-and I would love to hear the newer model, and how they have changed and benefited from more modern speaker design thinking. I might be mistaken, but it looks like the new woofers might use a paper cone. Paper is the way to go, in all speakers IMHO, but especially with Heils.
The Eminence 1040SF woofers I used are nothing shory of amazing, very sensitive and detailed, but can rock when needed-huge deep bass.
I think the newer AMT Heil lends itself better in 2 way designs, with a propely designed crossover, and matching drivers of course.
A efficient woofer is needed, and the older models can suffer from Alnico discharge, which lowers their output vs the Heil. A replacement, such as the 1040SF in the AMT3's, or a recone and recharge is the best route to take.
They also benefit frm a recap, and through checking of the crossover-resistors, connections etc.
ESS wasn't the only to suffer from Alnico discharge-a few JBL models did as well, especially when driven by high powered amps.
Just nice to see them back producing a great classic speaker(s) again. And at realitively sane prices, compared to the German models.
A new generation of Heil addicts!!! Awesome:thmbsp:

AMT# Heil Foam Wings

As promised some pics. I used some P.E. convuluted acoustic dampening foam I had handy.
The large blockes extending to the back are 2 pieces put together via convulutions-so the little gaps you see aren't important. You need to completely block off the side grills, as the rear Heil output is left open.
Not pretty but effective.
Alos, if you have one of the earlier models that has the perforatted top masonite board, you will have to fill the holes in.
Silicone should work, just a dap to seal off the holes.

See attached photo. Any speaker will have the imaging damaged by early reflections around the tweeter or midrange. It is always best to have similar baffle area around a tweeter and midrange if they are to transition smoothly over a large listening area. We all know of speakers that do not do this and they can work with the tweeter mounted without a baffle but the crossover and tunning will be trickier. Naked tweeter designs will also cross over above 2.5K for the most part where the ESS is 800 to 1000 Hz crossover.
The common comment is that the AMT can not mate up to a 10 or 12" woofer. This is more of a yes and no situation. In the later ESS speakers that used the 12" driver many of these are designed to carry well out over 1KHz. This is why there is an aluminum dome under the dustcap.
Careful rebuilding of the stock crossover will help smooth the transition. Quality caps to replace the originals are most important. If you bi-amp then you may also move the woofer forward one inch in time delay which will raise the height of the midrange transition especially if you use LR-4th order crossover.
The Audax 130s will take a while to settle in as they are a bit lean when new.
Thanks again,
Ron-C

Automojo, good job on your Rock Monitors. Did you notice the increase in bass definition after you put the foam in? The ear works in strange ways.

Thanks,
Ron-C

ron-c said:

Automojo, good job on your Rock Monitors. Did you notice the increase in bass definition after you put the foam in? The ear works in strange ways.

Thanks,
Ron-C

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Thanks Ron. You have been very helpful in my quest for the near perfect Rock Monitor(s)! :thmbsp: Very much appreciated!
Yes I did, especially in the midbass region. In fact on a few recordings it really widend and clarified the soundstage, and improved the focus to boot. A must upgrade for the AMT3 IMHO. Very noticeable improvement.
I am also going to use the foam around the mids on both pair when I get the chance. What thickness did you use?
Hopefully, with the help of AMT, we will get a good database going for AMT improvements-a one stop shop, so to speak.
Looking foward to getting those Audax up and running in the 2nd pair (hopefully by spring0, and broken in for a good comparison.
Does using the convuluted side up front help any, or just for looks? (I run with the grillls). I had a few various pieces left over- so that's what I came up with-but may put one in front in the future if it would help.
I see via photo I will have to try another 'v' piece as I left a slight gap on the left side.

Well the foam around the mids is kind of a band aid. The front panel of the AMT is thin and colors the sound. Other than rip the cabinet apart and replace it with a thicker one there are other solutions. The sides of the AMT3 and later 1AM speakers are very dead since this is a box with the sides over that so it is over 1.5 thick. The back and front panels are another story.

I like the 1 inch Sonic Barrier material from Parts Express to line the inside of the cabinets. Use the glue backing and a staple gun.

Depending on the condition of your cabinets you may want to run wood screws from the inside sides out so the two side panels are tight. On the front I have run 2" x 1/2" wood braces across the area between the mid and amp and between the two woofers. These are screwed and glued. A lot of work. Also use t-nuts and 8 mounting screws on the woofers.

If the cabinets are dried out a new coat of black paint on the front and back panels will be a big help and the particle board will soak the paint right up.

On the cutouts for the woofer you may want to coat with epoxy and let dry as this will stop the particle board from breaking apart.

See attached photos.

AMT1AM speakers have a brace between the 12" and 12" passive so they are much more stable. On any speaker this old it is always best to strip them down and check everything for seal and tightness. ALL seams should be caulked with silicone inside the cabinet and pay close attention to the seal of the midrange tube on the AMT3s.

Thanks again,
Ron-C

ron-c said:

See attached photo. Any speaker will have the imaging damaged by early reflections around the tweeter or midrange. It is always best to have similar baffle area around a tweeter and midrange if they are to transition smoothly over a large listening area. We all know of speakers that do not do this and they can work with the tweeter mounted without a baffle but the crossover and tunning will be trickier. Naked tweeter designs will also cross over above 2.5K for the most part where the ESS is 800 to 1000 Hz crossover.
The common comment is that the AMT can not mate up to a 10 or 12" woofer. This is more of a yes and no situation. In the later ESS speakers that used the 12" driver many of these are designed to carry well out over 1KHz. This is why there is an aluminum dome under the dustcap.
Careful rebuilding of the stock crossover will help smooth the transition. Quality caps to replace the originals are most important. If you bi-amp then you may also move the woofer forward one inch in time delay which will raise the height of the midrange transition especially if you use LR-4th order crossover.
The Audax 130s will take a while to settle in as they are a bit lean when new.
Thanks again,
Ron-C

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I would be very interested to see what the crossover point of the Heils would be in the AMT3 under discussion. The classic Heils were crossed over as low as 1000hz, but the response at that frequency could only be described as ragged. The response characteristics of the Heil have been discussed at length in various threads and there are some peaks at various frequencies that can cause sound anomalies. I experimented extensively with several type of Heil drivers and found that as designed, it was(is) best suited as a tweeter/supertweeter. One thing I've never done however, is block off the sides of the large Heil. It's a good idea that will help to make the Heil less placement sensitive. How about blocking off the rear as well? Since many of the smaller Heil drivers have their back wave cancelled by the enclosure, or by baffling material, it would seem logical that a mono-pole big Heil driver would be far less problematic in terms of placement and frequency anomalies.

The big AMTs sound great crossed over at 800. Some models did cross them over lower but they do not handle as much power as you go down in frequency like any other mid range driver. The issue is not so much where they are crossed over but the slope and how loud you play them. Today's typical crossovers are much steeper.
Optimum is no crossover of course using separate amps and electronic crossovers.

Thanks,
Ron-C

sealy said:

I would be very interested to see what the crossover point of the Heils would be in the AMT3 under discussion. The classic Heils were crossed over as low as 1000hz, but the response at that frequency could only be described as ragged. The response characteristics of the Heil have been discussed at length in various threads and there are some peaks at various frequencies that can cause sound anomalies. I experimented extensively with several type of Heil drivers and found that as designed, it was(is) best suited as a tweeter/supertweeter. One thing I've never done however, is block off the sides of the large Heil. It's a good idea that will help to make the Heil less placement sensitive. How about blocking off the rear as well? Since many of the smaller Heil drivers have their back wave cancelled by the enclosure, or by baffling material, it would seem logical that a mono-pole big Heil driver would be far less problematic in terms of placement and frequency anomalies.

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At least in my experience, blocking the rear of the Great Heil (dipole) doesn't present any advantages, and eliminates the airy quality of the Heil, another Heil advatage among others
I think being designed as dipoles, they probably work best as such, given the network design, and driver efficiency. Most of the smaller Heils were specifically designed as monopole drivers.
From what I have read, from ron, and others as well- the main problem is the mid frequencies wrapping around the Heil enclosure, not the rear output.
The AMT3's crossover point is stated at 700hz, but in practice I think it's between 800-100hz. They sound great.
Through crossover examination, and recap is for sure a must for optimum performance. With both pairs of my AMT3's I fould a few subpar, on the edge of failing componets and solder joints and connections. Resistors alos need to be looked at-both of my sets had flaky units.
Interesting fact (ron) on the aluminum cones/woofers-something I never heard of, and food for thought.
I always thought those later 2 way AMT monitors sounded great-no holes, nice flat frequency response-now I know why!
Ron, thanks for the excellent additional great info/ pics concerning the cabs-awesome!:thmbsp:
They always seemed fairly resonate free to me (as comparing them to a set of Klipsch).-More upcoming work I see on my second pair!
The midtube sealing is a must as well, it makes a noticeable improvement-plus it just makes sense given the design.
Luckily my 4 cabs are solid, I ran expoxy in the joints, and sprayed the inside of the front baffles with Quiet Kote-something I forgot to mention in previous post.
As a alternative to biamping/ electronic crossovers, the ESS AMT3 3 coil crossover and design seems to be a great starting point for someone trying to build a nice AMT Heil speaker, without breaking the bank, or searching for the above mentioned woofers etc.
The simpilicty of the Great Heil, and the basic ESS design (s) is a good foundation for a truely great speaker. Sure some work is needed, but it's not hugely difficult work, (easier than installing new tweeter wires on a Magnepan!:thmbsp_ time consuming for sure, but not difficult. And alot of the trial and error has already been done-a glimpse of that here already.

All the great info and thoughts/inputs from everyone is much appreciated-this turned into a extremly informative thread (for me at least!) on Heil/ESS speakers.
I'm going to give Rick a call at ESS when I get the chance, and see if I can get some specifics on those new ESS speakers.
I am extremely curious on the network/driver makeup, along with cabinet construction as well.
Again thanks for all the great input-feel free to keep it coming!

From what I see on Michael Otto's ESS documentation archive, it appears that the AMT-3 crosses over at 250Hz and 1000Hz.

I find this discussion on AMT tweaking very interesting. As some of you know I have a pair of AMT 1Cs, which do not have the monitor framework to stuff the sides like the monitors you have do.

How critical is stuffing the sides flat to the front? Could the sides of the covers be closed off to accomplish a similar effect? What about the fact that my 1C has an upward angled Heil? How would that be compensated for?

I also find it interesting that one of the other highly regarded AMT designs, the AMT Tower, did not have open side panels, but a large 'tunnel'. It was not padded or dampened on the sides in any way though. I wonder how that model's design compares to some of the others/tweaks mentioned here.

Ron-c, you mentioned that biamping could benefit from moving the woofer forward. I modified my crossover to facilitate passive biamping, per this thread:

http://www.audiokarma.org/forums/showthread.php?t=330631

Does that comment apply in this case, or only when active crossovers are used?

I am thinking that I need a recone/recharge on my woofers, which could be much of the reason that I needed to biamp these. Hard to say. Would that be the best way to go, or would replacing them work better? If so, how much crossover work would be needed? I would prefer to keep that to a minimum.

Thanks for all of your help. I find all of this ESS discussion lots of fun to follow, and who knows, if I stumble upon an AMT 3 cabinet maybe I'll get to do this myself someday.

IBJamon

The original AMT3 manual states the crossover points at 250 and 700hz, but the slope of the crossover may lend itself closer to to 800hz, or perhaps higher.
The 3 coil designs I have seen are all pretty much the same design.
The AMT1c would be different. The AMT1d apparently used a different crossover design, which was said to improve the transition point between the woofer and Heil. I haven't been able to find specs on this, so I can't guarantee it's different or not. I do see ESS has crossovers available, what models/types I'm not sure.
Seem like you have, from your thread done a good job with the crossover.
Also stabilizing the cabinet, sealing and such should be beneficial. The few AMT "classic" cabinets I have seen seemed to be a bit on the loose side, but those had a rough life as I recall.
I am not sure if their is a good repalcement for the Bextrene woofers. They also have squared off sides, which would require some reworking to go with a traditional round woofer. If they have Alnico magnets, they can be recharged. ESS now offers complete woofer overhaul and recharging.
Given what ron has mentioned, that they may have aluminum cones to help deal with the transition and coupling, I would opt for a recharge, and or recone if needed. ESS also has this service.
If the woofer has significant lower output than the Heil (it shouldn't if operating correctly), then it needs a recharge.
I opted to go with the OCS recommended 1040sf's after alot of research. They work well with the other drivers, and can really play extremely loud without distortion, one of the main things I was looking for, in both of my pairs.
As far as blocking the sides of the Heil on the AMT1c, I can't recall how the grill and framework design is inside, but you should be be able to make wings, and perhaps a top sealing piece to at least minimize the 'wrap around' effect. I don't think it would too critical to have the foam even with the front housing of the Heil, as you are mainly trying to block the rear waves wrapping around-but I can't see why you wouldn't be able to make it flush-just avoid sharp shapes protruding from the foam block.
I would get some foam and start experimenting.
Those AMT1c's are fine speakers, and worth the time and effort to tweak.

ESS AMT3 Manula and Specs

Hopefully this helps.

How interesting! There must have been at least two versions then, because the brochure at this link:
http://new-hifi-classic.de/Gallery_MO/displayimage.php?album=82&pos=7
clearly shows 1000Hz. The original AMT1/Tower were 700Hz also, so there may have been bad communication somewhere, who knows.

The 1C is built pretty sturdy. While it could use some cosmetic TLC, it doesn't flex at all that I can tell. I have read some say it was built better than the 1D, though the crossover may be a different matter. I will have to seal it, though. Rick at ESS recommended auto undercoating for sealing the inside. Seems like a decent plan. I just have to figure out the best way to mod in my biamp wiring without butchering the box too much. I'll probably get some dual binding posts when I finally bite the bullet and send in the woofers. Hopefully I can have that done this spring.

Speaking of the woofers, I don't recall seeing an aluminum cap when I was putting these together, but I did notice that there were dual dust caps, of which one was missing. There was an inside dust cap, which remains, and an outside one that is a bit larger that is missing. I actually have one of them, but since they are a pair, I'm not going to have one speaker with and one without so I left it off. Perhaps this was one iteration of this extra stiffening before they went with the aluminum caps.

Thanks for your input!

IBJamon

IBJamon said:

How interesting! There must have been at least two versions then, because the brochure at this link:
http://new-hifi-classic.de/Gallery_MO/displayimage.php?album=82&pos=7
clearly shows 1000Hz. The original AMT1/Tower were 700Hz also, so there may have been bad communication somewhere, who knows.

The 1C is built pretty sturdy. While it could use some cosmetic TLC, it doesn't flex at all that I can tell. I have read some say it was built better than the 1D, though the crossover may be a different matter. I will have to seal it, though. Rick at ESS recommended auto undercoating for sealing the inside. Seems like a decent plan. I just have to figure out the best way to mod in my biamp wiring without butchering the box too much. I'll probably get some dual binding posts when I finally bite the bullet and send in the woofers. Hopefully I can have that done this spring.

Speaking of the woofers, I don't recall seeing an aluminum cap when I was putting these together, but I did notice that there were dual dust caps, of which one was missing. There was an inside dust cap, which remains, and an outside one that is a bit larger that is missing. I actually have one of them, but since they are a pair, I'm not going to have one speaker with and one without so I left it off. Perhaps this was one iteration of this extra stiffening before they went with the aluminum caps.

Thanks for your input!

IBJamon

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Intersting on using the undercoating-Quiet Coat is similiar-more expensive for sure-but doesn't stink as bad either.
I see in the P.E. reviews many claim it works better than undercoating for dampening purposes. Although glue or epoxy may be helpful for strengthening purposes.
Perhaps the difference in the crossover specs has to do with the actual slope, thus the real spec vs published spec.

chef free said:

I've ordered a pair of Audax my self!

I have found that these speakers sound best toed in much more than I'm used to. I have them pointing to the middle of the room to where I can see the outsides of the speakers from the couch.

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Interesting, in my living room set up, I can't really toe the speakers, but having them straight on, with the foam block yeild some pretty wide imaging. I was listening to some Christmas music with the kids, and I could look about 60 degrees from my straight on listening position (to the left)and clearly hear the flutes coming from this location.
Of course you give up the pinpoint imaging-but it's fun to play with the positioning and the results it yeilds. Alot of this is really a personal taste of course.
Some truely amazing speakers-and a lot of fun to upgrade and tweek.
I have learned alot, and enjoyed some incrediable music over the past 2 years or so playing with and rebuilding the AMT3's.
Well worth the realitively modest price of admission!
Again-thanks for all the great info and comments:thmbsp:

crossover

Cool, Automojo. Your "mojo" is working.

Aw-Christmas is over- and I didn't get my new ESS LD-10LR's!
Oh well!:thmbsp:
Hopefully they will get some specs published for these. Personally I think these would be a great alternative to some of the Zu speakers models that seem to get so much praise recently-particuliarly the Essense, which uses a ribbon. I bet the real world efficiency specs would be similar.
Finally got those Audax midwoofers in per RonC's recommendation. Very well made drivers apperance wise.
They won't fit the tube without a adapter. I originally was going to use a plastic, but decided on some treated hard board which should be denser, and easier for me to work with. My Dremel should work just fine. I will coat both sides with epoxy, and finish with some black paint to stabilize and seal the material, and pobably a shot of Quite Kote as well.
Almost done hard wiring one crossover, and will post pictures when I'm finished, along with a layout/wiring route diagram which hopefully be helpful for those attempting a ground up AMT3 crossover- it looks realitively simple, but particuliarly the midrange and tweeter circuits you have to pay close attention, at least in my case!

I have the chance to get a pair of AMT1 Tower's. The cabinets are trashed and no woofers. I would buy them mainly to get the Heil tweeters and the crossovers. Do you ESS experts think the Heil mid-tweeters will need new diaphragms even if they seem so work ok? I think I've read somewhere that the plastic can harden with age. I can get them at a reasonable price, but if I have to buy new diaphragms I want to figure that into the bargain. I think they would be good starting components for a fairly high efficiency speaker system with some woofers that can keep up. They're about 95 or 96 dB sensitivity aren't they? I have some sub 10 watt tube amps and some that are in the 20-30 watt range.

Thanks,
John

I've never seen an ESS require new diaphragms unless they are physically damaged. Within my family (myself, dad, bros) we have 16 Heil tweeters and only 2 have ever had to be replaced, both from physical damage. So I would inspect them closely.

IBJamon

The Great heils are pretty tough, and protected by a fuse-the fuse will blow before the Heil diaphram is damaged.
I had a set of ESS PS-1220's (bought new in 1987)in the 80's and early 90's-I had to replace a few diaphrams due to room mates driving my 150wpc Kenwood amp into clipping-as the ESS speakers sound so clean with little to no distortion-everything sounds good till the Heil diaphram melts.
These speakers had no fusing, and acounted for the diaphram failures.
I wouldn't worry about the age of the diaphrams, they will be fine-nothing to worry about-if they work then your fine.
There is some debate on the sound of the 'screened' Great Heil diaphrams vs non screened ones-nothing to worry about IMHO, and certainly not worth buying new diaphrams to replace perfectly funcion ones.
ESS speakers IMHO sound best with SS amplification, but more than a few Heil addicts here have good luck with tube amps.
Even though they are efficient, I would recommend a minimum of 100wpc (4 ohms)of good amplification-200-350 wpc is even better, as it really takes control of these speakers,even at low volumes levels-the difference is quite audible.
I recently aquired a Acurus A250, which puts out 350 wpc@ 4 ohms, and it really sounds wonderful-almost a twin to my Signature 1.5 that also has 350 wpc @ 4 ohms. Both are extremely clean sounding amps-which IMHO really benefits the AMT3's, as they don't need any sort of sound coloration.
The Eminence 1040SF 10" woofer OCS sells is a excellent, high efficiency woofer that mates up well with the Great Heil. I used them to upgrade the OE woofers in my 2 pairs of AMT3's with great success. The bass is very quick and very detailed, and comes in larges amount when the program material calls- and keeps up nicely with the Heils. It will also play at very high volume levels with no distorion.
Paper cone woofers are the choice here-ronc also had good luck with a Dayton ST255-8, which is made by Eminence, very similiar to the 1040SF with a larger magnet, and treated cone, and a larger voice coil.
Recently speaking with Eminence regarding this woofer, the 1040SF was OE'd specifically by OCS to be a viable, and realitively inexpesive upgrade for ESS 10" woofer speakers, thus the vas is almost perfect for the AMT3 enclosure. In fact, this speaker continually amazes visitors to my home-they can hardly believe it is a 1974 design (with a few upgrades!)-as it is a very detailed, musical and dynamic speaker at all volume levels-a unique trait of Heil speakers-they sound so clean from low to high volumes-with out the horn drawbacks or harshness-effortless music vs the forced music of most horn speakers.
The biggest challenge to upgrade these older ESS models is finding a woofers that can not only keep up, but have a similar output as the Heil. The OE woofers aren't really that bad-but given their age they really need to be reconed, and their Alnico magnets recharged-(to prevent low bass output, or muddy or overly warm bass) which puts you $10-$25 more than the 1040SF-which benefits from modern materials and design methods.
ronc can vouch for the Dayton, but I can say from my experience, I can't imagine a better replacement woofer for the AMT3's than the 1040SF-or any other 10" woofer AMT) truely makes this speaker, with a few other upgrades, a world class speaker IMHO-one that makes visitors ask-"what kind of speakers are those?".