I've attached both the throat adapter STL and what should be a pretty accurate model of the actual ESS AMT-1 for anyone to use. I can always add the tractrix geometry in here as well.
One thing I've been toying with is this - I'm a program-expert at a parametric modelling tool called Grasshopper, which I think could have some relevance to horn design. Basically, it integrates some of the horn calcs normally done in spreadsheets with a 3D modeling program called Rhino through an interface that uses inputs and sliders with mathematical equations to generate geometry - it's how I generated the tractrix curve for the panel. Once I make a little leeway on that I'll post some information.
I have done some residential but I'd say my bread and butter is cultural and performing-arts work; I'm lucky enough to get to work with some of the best acousticians in the country doing concert halls and theaters, and see a bit of an overlap between my personal audio passion and my profession. I just finished up working on a project for the San Diego Symphony, which just re-opened and apparently sounds fantastic.
One thing I've been toying with is this - I'm a program-expert at a parametric modelling tool called Grasshopper, which I think could have some relevance to horn design. Basically, it integrates some of the horn calcs normally done in spreadsheets with a 3D modeling program called Rhino through an interface that uses inputs and sliders with mathematical equations to generate geometry - it's how I generated the tractrix curve for the panel. Once I make a little leeway on that I'll post some information.
I have done some residential but I'd say my bread and butter is cultural and performing-arts work; I'm lucky enough to get to work with some of the best acousticians in the country doing concert halls and theaters, and see a bit of an overlap between my personal audio passion and my profession. I just finished up working on a project for the San Diego Symphony, which just re-opened and apparently sounds fantastic.
@xrk971 - given the results I have, do you think it's possible to do a decent two-way speaker with some acceptable sensitivity for a tube amp? I think I could MAYBE design a two way crossover but I think getting into a 3 way is going to be a bit above my head, and I'd like to try a passive speaker as I have a pretty nice 2a3 amp I'd like to pair with it. I was looking at the Falital 15PR400, as it seems to be vetted and used by several reputable makers, but I don't know if asking that to go too high is going to be a problem. It has good sensitivity and the FR graph appears outstanding but I'm pretty much a newbie when it comes to speaker design that isn't replicating or modifying a vetted design.
The AMT-1 goes very low with a horn as you have seen so a 2 way with a woofer that has bass and midrange is a good plan. Faital Pro makes nice drivers. 2 way XO is not that hard and I can help walk you through it. You have all the tools and measurement gear already. If your don’t have a DATS yet, that would be good to get. It is needed to measure the impedance curve needed to simulate the XO.
15PR400 is a very nice woofer. From curves I see that it has directivity that is pretty even up to 1000Hz. Choose that for XO point and make tractrix mouth width same as woofer diameter (at surround midpoint). This will let the frequency response and natural directivity (based on source diameter) match for a seamless transition. Try either a basic 2nd order symmetric. But my choice would be an asymmetric absolute positive phase quasi transient perfect Harsch XO. The Harsch will be perfect since tweeter is setback for nice time alignment. 4th order on woofer and 2nd order on tweeter. Look at my Harsch XO thread for details. We can discuss more on this this thread or that thread.
And to answer your question, can a wimpy fleawatt tube amp work? Yes. But to be honest, a speaker of this statute deserves a good 25w to 40W Class A amp. You can also use Class D and a tube preamp to give it sonic character.
100dB on woofer in open space is 94dB sensitive after baffle step loss. AMT-1 in horn is about 92dB to 95dB. Probably perfect and no padding needed. 3-5w amp will drive this to nice loud levels with headroom.
15PR400 is a very nice woofer. From curves I see that it has directivity that is pretty even up to 1000Hz. Choose that for XO point and make tractrix mouth width same as woofer diameter (at surround midpoint). This will let the frequency response and natural directivity (based on source diameter) match for a seamless transition. Try either a basic 2nd order symmetric. But my choice would be an asymmetric absolute positive phase quasi transient perfect Harsch XO. The Harsch will be perfect since tweeter is setback for nice time alignment. 4th order on woofer and 2nd order on tweeter. Look at my Harsch XO thread for details. We can discuss more on this this thread or that thread.
And to answer your question, can a wimpy fleawatt tube amp work? Yes. But to be honest, a speaker of this statute deserves a good 25w to 40W Class A amp. You can also use Class D and a tube preamp to give it sonic character.
100dB on woofer in open space is 94dB sensitive after baffle step loss. AMT-1 in horn is about 92dB to 95dB. Probably perfect and no padding needed. 3-5w amp will drive this to nice loud levels with headroom.
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I wish I hadn't seen this thread. About 24 years ago I bought a pair of Grand Heils with every intention of using them in a 2way open baffle design. With no experience of speaker building this was I soon realised an ambition too far. The difficulty was finding a woofer that would do the job. The x/over - to follow ESS or what? Studying what people were doing with the Heils at that time - leaving them free of any enclosure or even suspending them to eliminate any vibration or inter-reaction with the woofer. Suspending them would mean building really strong supports (they weigh a ton).
This would definitely be my last project - what should I do - I'm not equipped to build really complicated baffles or even more complicated horn designs, if it all seems too much I'd like to sell them to someone who could use them to good effect. The man I bought them from had a pair of original AMT1 - they were powerful and authoritive speakers.
This would definitely be my last project - what should I do - I'm not equipped to build really complicated baffles or even more complicated horn designs, if it all seems too much I'd like to sell them to someone who could use them to good effect. The man I bought them from had a pair of original AMT1 - they were powerful and authoritive speakers.
Just get a decent 10 or 12" woofer and go from there. As an example on the ESS site.
Rob 🙂
https://essspeakers.store/collections/black-friday
Rob 🙂
https://essspeakers.store/collections/black-friday
@xrk971 Thanks for all your insight, appreciate it. I might have to give up on the 2A3 - to be honest I bought and assembled the kit way back when I was just getting into the hobby just because I thought tubes "looked cool" and had literally no other context beyond that. I quickly realized it doesn't pair well with most modern speakers - so it might be time for me to give up on trying to find a pair for that experiment.
I have used DSP in the past to do some crossovers and it could be that maybe I go that route to enable experimentation as I get more into the hobby. The only thing I haven't quite figured out is the best way to do multiple (8?) high quality channels without completely blowing the budget.
I built the console below with a miniDSP + two ICE amps and the PS-14 preamp kit. It doesn't rattle the doors on the house but sounds pretty decent to my ears.
I have used DSP in the past to do some crossovers and it could be that maybe I go that route to enable experimentation as I get more into the hobby. The only thing I haven't quite figured out is the best way to do multiple (8?) high quality channels without completely blowing the budget.
I built the console below with a miniDSP + two ICE amps and the PS-14 preamp kit. It doesn't rattle the doors on the house but sounds pretty decent to my ears.
Attachments
Beautiful console! I recognize that TB coaxial and have a nice passive crossover design for it for @Vunce a few years back. He uses it in a TL but I think it should work fine in most cabinets with a not too wide of a baffle.
You could skip the DSP if you went all passive.
There is a trick to getting a decent sounding miniDSP on 8 channels under budget. Use their basic 2x4 $80 unit and buy two. You have to program each separately but not an issue for a long term use like console or real active speaker.
You could skip the DSP if you went all passive.
There is a trick to getting a decent sounding miniDSP on 8 channels under budget. Use their basic 2x4 $80 unit and buy two. You have to program each separately but not an issue for a long term use like console or real active speaker.
Thanks a lot! I will modify it as (if) needed. Another 2 way MEH is on the way, with a smaller midbass🙂
Do you see any parameters for the ESS 12" woofer anywhere? How are you supposed to develop crossover without data..?
12" info here . 10" info here .
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689-2012 ESS Factory 12 Inch Woofer
Regular price$199.00Quantity
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| Product Specifications | |
| Nominal Diameter | 12" |
| Power Handling (RMS) | 200 W |
| Power Handling (Max) | 300 W |
| Impedance | 4 Ω |
| Frequency Response | 29Hz - 15kHz |
| Sensitivity | 91.5 dB 1W/1m |
| Voice Coil Diameter | 2" |
| Magnet | 35 oz |
| Thiele-Small Parameters | |
| Resonant Frequency (Fs) | 24 Hz |
| Qes | 0.52 |
| Total Q (Qts) | 0.47 |
| Compliance Equivalent Volume (Vas) | 6.69 ft3 |
| Le | 0.73 mH |
| Qms | 4.9 |
| Xmax | 6 mm |
| Re | 3.9 Ω |
| Materials of Construction | |
| Cone Material | Paper |
| Surround Material | Rubber |
| Magnet Material | Ferrite |
| Voice Coil Former | Aluminium |
| Voice Coil Wire Material | Copper |
| Basket / Frame Material | Cast Aluminum |
| Mounting Information | |
| Overall Outside Diameter | 310 mm (12.375") |
| Baffle Cutout Diameter | 280 mm (11.125") |
| Depth | 160 mm (5.625") |
| Mounting Holes | 4 |
- Original ESS-AMT™ design, treated paper cone, rubber surround
- Factory new direct replacement woofer
ESS Factory 10″ Woofer 689-1010
Regular price$189.00Quantity
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| Nominal Diameter | 10" |
| Power Handling (RMS) | 80 W |
| Power Handling (Max) | 160 W |
| Impedance | 4 Ω |
| Frequency Response | 45Hz - 24kHz |
| Sensitivity | 90.6 dB 1W/1m |
| Voice Coil Diameter | 1.5" |
| Magnet | 35 oz |
| Thiele-Small Parameters | |
| Resonant Frequency (Fs) | 27 Hz |
| Qes | 0.54 |
| Total Q (Qts) | 0.48 |
| Compliance Equivalent Volume (Vas) | 1.75 ft3 |
| Le | 1.2 mH |
| Qms | 4.1 |
| Xmax | 4 mm |
| Re | 3.4 Ω |
| Materials of Construction | |
| Cone Material | Paper |
| Surround Material | Rubber |
| Magnet Material | Ferrite |
| Voice Coil Former | Aluminium |
| Voice Coil Wire Material | Copper |
| Basket / Frame Material | Cast Aluminum |
| Mounting Information | |
| Overall Outside Diameter | 269 mm (10.625") |
| Baffle Cutout Diameter | 238 mm (9.375") |
| Depth | 114 mm (4.5") |
| Mounting Holes | 4 |
- Original ESS-AMT™ design, treated paper cone, rubber surround
- Factory new direct replacement woofer
I recently purchased a pair of Heil AMTs + mounting kits for $250 + shipping (they are very heavy, think two chunks of ferrite). I first heard the ESS AMT-1 in 1974 when I was a junior in high school. My dad came home from work one day and said "You've got to hear these speakers!" We immediately went to the showroom. The ESS AMT-1. The sound was incredible. The midrange and treble was the best I have heard. The best cymbals. The sound seemed to float in space, super clean, extended and realistic. The midrange was pristine. Deep bass of the AMT-1 was excellent. The problem was the crossover area and integration of the two drivers. But the Heil AMTs...Wow! The way they produce sound is very realistic. Unfortunately, the price was out of our means. Then pursuing a career path. Followed Heil AMT from a distance. Once the patent runs out, there are more AMTs, but the models seem to come and go. Decided to spring for these since they would be good for experimentation. They can simply sit on top of a cabinet. Also, the company seems to be mainly a warehouse at this point. Could be wrong. Yes, they make the AMT-1D Revival, but if it seems to be a clone of a flawed speaker.
https://essspeakers.store/collections/speakers/products/amt-limited-edition-pair
Plan to try biamping with the bass cabinets I have on hand using passive line level crossovers. Hopefully first order. It seems the crossover frequency could be low enough.
https://essspeakers.store/collections/speakers/products/amt-limited-edition-pair
Plan to try biamping with the bass cabinets I have on hand using passive line level crossovers. Hopefully first order. It seems the crossover frequency could be low enough.
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This was nearly 10 years ago - I put them on top of a Z baffle with two RS225’s. Active crossover.
Distortion was very low:
Distortion was very low:
So I've been kicking around different designs with the Heil and a waveguide and I remembered that I bought a pair of Kappalite 3012 HO drivers a LONG time ago and they've been sitting in a cabinet. It's a mid-bass / midrange driver that seems to be fairly well behaved to a 1khz crossover point, but the F3 on even a very large cabinet is still about 50 hz. I already have the driver, so it would be nice to use, but do you think this might be a good pairing with the Heil in the horn I'm working on? Any way to get that Fs lower? I'm not afraid of complex constructions.
https://eminence.com/products/kappalite_3012ho
By the way, that dipole is awesome. I have a pair of Dayton Audio PS220's I've been meaning to put into a Karlsonator 8 (I think incidentally of your design @xrk971 ) but I haven't gotten around to it. I think there's an elegance to that form that is really nice.
Here's a render I did a while ago - hoping to someday finish the project.
https://eminence.com/products/kappalite_3012ho
By the way, that dipole is awesome. I have a pair of Dayton Audio PS220's I've been meaning to put into a Karlsonator 8 (I think incidentally of your design @xrk971 ) but I haven't gotten around to it. I think there's an elegance to that form that is really nice.
Here's a render I did a while ago - hoping to someday finish the project.
I've been using the Heils in this ugly-but-effective dipole setup for a few years, with a pair of RSS315HF-4 subs for the bottom end. The mid is a Beta 8a, the woofer is a Faital 15FH500. 4-way DSP crossover with miniDSP 4x10HD. I may try to make a more attractive version some day, but there are a couple of projects in the queue before that, the first of which is to get my shop space back in operable condiditon!
I would think the Kappalite would mate OK with the Heil, but it will never go deep.
I would think the Kappalite would mate OK with the Heil, but it will never go deep.
