I use tge miniDSP to figure out the best xo points and such then build passives to that. I am also building a 3 way active tube crossover using Steve Benches boards.
So, not every ****ing thing needs to be digital but it has its place.
Another ESS AMT-1a pyramid rebuild thread
- Thread starter 13stoploss
- Start date
I use tge miniDSP to figure out the best xo points and such then build passives to that. I am also building a 3 way active tube crossover using Steve Benches boards.
So, not every ****ing thing needs to be digital but it has its place.
NoTransistors
Dual Turntables Super-Restorer
My girlfriend, who passed last spring, used to say,"Never trust anyone who does not curse every now and then."
Porkloin
Oscar Heil Groupie
I've only seen Ralph's writings on the internet and have never met the guy personally. He was more than happy to share the crossover recipe in his review of the Tangband W8-1772 over at Parts Express (see review by HiFiRalph). The capacitor value came from his review of the ESS AMT that's no longer on sale at PE.
There's SIX woofers in each speaker. It looks to me that they're arranged in a Linkwitz "W"-Frame setup as seen in this article sent by @Poultrygeist.
From what I gather, Ralph was selling the speaker setup complete with one of the Crown XLS amps for the woofers. The Crowns have an active crossover in them, so that covered the low-pass for the woofers. That, coupled with his first order passive crossover for the upper drivers was quite an elegant solution.
Porkloin
Oscar Heil Groupie
I've been curios about that enclosure with the red waveguide on top for quite some time, but just now get around to asking: Is that brass plated baffle?
Porkloin
Oscar Heil Groupie
1. Test the DC resistance across the speaker input terminals. You'll get the DC resistance of the woofer, along with the (negligible) DC resistance of the large inductor coil in series with it. I believe that the woofer in the 1a was rated 4 ohms impedence, so you should see about 3 ohms on a DC ohm meter. The tweeter circuitry has a capacitor in series and will not pass the DC test signal from your meter, so it's a non-issue. If the woofer is 8 ohm, you'll get a DC resistance reading of about 6 ohms.
2. If you get infinite resistance, I'd suspect a loose connection, if your woofer was working fine to begin with. If you had a voice coil issue due to a cone not being centered when you did the refoam, that would've showed up when you first started listening.
3. Measure the DC resistance of the woofer removed from the circuit. If you get the 3 or 6 ohms DC resistance, start looking for loose connections.
4. If you get 3/6 ohms resistance when measuring the woofer, but NO resistance when measuring across the input terminals of an assembled speaker, disconnect the woofer and measure across the ends of the larger value capacitor that parallels the woofer. It should read infinite, but although it's rare, a "fused" capacitor would provide the path of least resistance and the woofer wouldn't be getting any juice. If it reads NO resistance, replace the cap. NOTE: Conventional wisdom says that lower frequencies do not benefit from poly-caps. If you run into a bad cap in the woofer circuit, your money would be better spent on a six pack and an electrolytic cap ($1.50) than a poly-cap ($10)
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Hey Porkloin,
I'm waiting for AutoMojo to get back to me, he might have a copy of the specs for the original AMT3 crossovers. He's looking. I plan to compare anything I can review first.
I have some original AMT Monitor (never used) passive crossovers and original an ESS Eclipse 2241 active/electronic crossover I might sell off if I can recreate the factory AMT3 crossover from scratch using new -upgraded parts. I'm so pleased with my DEC-AMT28 speaker project, now I'm considering doing an AMT3 recreation from scratch. Do you have the copy by chance? Thanks.
I'm waiting for AutoMojo to get back to me, he might have a copy of the specs for the original AMT3 crossovers. He's looking. I plan to compare anything I can review first.
I have some original AMT Monitor (never used) passive crossovers and original an ESS Eclipse 2241 active/electronic crossover I might sell off if I can recreate the factory AMT3 crossover from scratch using new -upgraded parts. I'm so pleased with my DEC-AMT28 speaker project, now I'm considering doing an AMT3 recreation from scratch. Do you have the copy by chance? Thanks.
Porkloin
Oscar Heil Groupie
If you're referring to the crossover for the earlier AMT-3's that had a pair of 4 ohm woofers, you may have a bit of a wait. I don't think even @automojo has that drawing. The attached drawings are for the more common, new models with the 8 ohm woofers. This may be the way to go anyway, if you're starting from scratch.
This crossover may worthwhile only if you're using similar drivers to the our AMT-3 configuration.I If you use something different, like the above mentioned Tangband driver from the Surreal Sound speakers, that would require rethinking parts of the crossover.
If you can find a 4 ohm L-Pad, it may be an upgrade to use it to replace the (3) resistors running horizontally, although, oddly, the rotary switch is more readily available.
This crossover may worthwhile only if you're using similar drivers to the our AMT-3 configuration.I If you use something different, like the above mentioned Tangband driver from the Surreal Sound speakers, that would require rethinking parts of the crossover.
If you can find a 4 ohm L-Pad, it may be an upgrade to use it to replace the (3) resistors running horizontally, although, oddly, the rotary switch is more readily available.
Porkloin
Oscar Heil Groupie
Any pictures of the DEC-AMT28 project?
Sure. Finished these two years ago. AMT with dual 8s. I've always wanted to try this in a D'Appolito configuration. With a tube preamp front end, I've been testing it on a 200w Cary 200.2 solid state amp and Cary V12R 50/100w tube amp so far. At 92db or so, now on to a low power Triode amp this week to see how they react. Hope the link works, pictures seem to appear and disappear on google images... thanks for the AMT x-over spec. Interesting.
DEC-AMT28 rainy day project
Porkloin
Oscar Heil Groupie
Yeah, OK. I've seen those here before. They look great. Why try to replace with a tribute to the AMT3, unless you've got the typical "audiophile restlessness"?Sure. Finished these two years ago. AMT with dual 8s. I've always wanted to try this in a D'Appolito configuration. With a tube preamp front end, I've been testing it on a 200w Cary 200.2 solid state amp and Cary V12R 50/100w tube amp so far. At 92db or so, now on to a low power Triode amp this week to see how they react. Hope the link works, pictures seem to appear and disappear on google images... thanks for the AMT x-over spec. Interesting.
DEC-AMT28 rainy day project
Porkloin
Oscar Heil Groupie
Yes. True. You got me. A) 2.5-way, done, check.
Two new things I want to try, maybe, still investigating.
B) small compact 95db+ efficient 2-way with AMT for low power 10w triode tube amp (ESS or other AMT)
C) future 3-way, with AMT, all new drivers and crossovers from scratch, for 100w+ tube or solid state amp (likely ESS Great Heil AMT).
Thanks again for the spec.
Porkloin
Oscar Heil Groupie
I've been kind of Jonsing (off and on) to do an open baffle with an AMT, the pictured Tangband and a couple of Alpha 15 woofers. It's pretty hard to justify while I'm still enjoying the Rock Monitors.
I came real close to doing a set of open baffles last summer. Seemed to be the rage with a few guys the past few years. I was following the Pure Audio Project guys with their AMT/Heil version, and watching Hawthorne Audio on theirs. Appears the PAP stuff moved on to other types of configurations and saw a few versions with AMTs for sale shortly after. I realized I don't have the right listening room or seating distance for baffles to operate properly. Would love to try a set some day, but I'm with ya, what we are both running now is keeping me content a bit for me now too...
I received my Audyn 6.8 mfd caps and with a Mills 12 watt, 4 ohm resistor in series with the Heil, they sound absolutely beautiful! (Mine are of the low impedience versions.) They now sound so much better, and louder, than when I was using the ESS CE-2 crossovers the original owner provided with them.
With the 4 ohm resistor, they are a nice match for the JBL 10"s and at this time no L-pad seems necessary.
I'll put the RTA on them and see what they are doing.
With the 4 ohm resistor, they are a nice match for the JBL 10"s and at this time no L-pad seems necessary.
I'll put the RTA on them and see what they are doing.
Rock Monitors are cool!
A local offering for three bills. Completely restored/refoamed. Just don't want to make the drive across LA.
Porkloin
Oscar Heil Groupie
By "LA", I'm assuming you're referring to Louisiana.Rock Monitors are cool!
A local offering for three bills. Completely restored/refoamed. Just don't want to make the drive across LA.
Those are worth the state-wide drive. If you don't have a wife to ride shotgun, start schmoozing that curvy divorcee down in accounting and make a road trip of it.
