Could an AMT woofer be made by upscaling the dimensions ?
Interesting system Bob. Is that the Great White Horn you're using?
I've never heard it called that but it's an EV HR60 and driven with 288Cs with 8 ohm diaphragms. I couldn't find them in the US and after months of searching these turned up in Germany.
It's an incredible system and I can only thank Evert Veenstra, who you know here as AltecLansingFan, for convincing me to build it, finding the horns, and walking me through the crossover. He recently convinced me to try some quality cables and as a skeptic about that whole thing I was reluctant to try them and very surprised at the noticeable improvement.
It was four months after I had assembled all of the parts before I got to it and only took a day to put it all together. I really liked the stock 620As that I was using and I was in no hurry to get rid of them. However, I couldn't believe my ears when I hooked these up and six months later I'm still blown away.
It has a 416-8B and a modified Model 19 crossover with an added capacitor for the tweeter at 9K. The 620A cabinets are a perfect match for the 416-8B and the rest is simply a good match of speaker components along with a Dynaco CDV-2 CDP, a McIntosh MX110 preamp and a McIntosh 240 amp. BTW the Model 19 crossover on the cabinet is just plugging the hole and has been replaced with a piece of plywood.
Bob Walker
If keeping to the original design/two way with passive I would use an altec 414c for the mid/woof. I am new here but the explanation was the Heil being super quick needs the fastest midrange you can get. I did away with the passive radiator and used a modified transmission line with the altec and am quite pleased with the results. Blows away the original AMT1's or the KEF 104/2's they replaced in quickness/transparency. The 12" is also recommended over the 15" only because it is important to keep the large tweet/mid Heil as close to the mid/woof as possible. Mine sits on top the absolute minimum separation- within 3/8" of the frame! Love the sound. Recommended.
I was spending too much time and money so gave up trying Altec crossovers and even active (fried a good amp with a shorted patch cord). So went back to the original AMT crossover and upgraded the parts. I believe mine is series "c" with a crossover at 800 hz with a 12 db slope. There is (what the members here already know) a midbass bump that I think is characteristic of the altec and not the crossover, but It gives an interesting punchiness. Not sure how to smooth that out while using the existing xover. Still I am quite pleased. This is my first truly transparent speaker.
...and I found you while looking for what else has happened in the intervening years. I'm the one who built those horn-loaded AMTs back around 1980 and had the article published in Speaker Builder, in one of its early issues. If you have any questions, I'm available for comment.
Ken Rauen
Anybody interested in a nice clean pair of ESS Heil AMT's that work in the ESS L4. LS5, or LS8?
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