Another ESS AMT-1a pyramid rebuild thread

Are those bypass caps or additional caps paralleled in to achieve a given value?

Those are Theta .001 Film/Foil Bypass Caps.
I did all the XO mods at once. It's a very constricted area for these upgrades and I didn't want to revisit taking everything apart again to add the Theta's later.
 
If you don't have the Elite any more, there's a cavalcade of far more flexible crossovers/speaker management systems out there, although I've heard some talk that ESS was still selling some new/old stock for a song.
I may be one of the few to give a thumbs up to an Emotiva amp for vintage speakers. I like the idea of a giant transformer and a buttload of capacitance as mine runs extremely cool, but I got it for the high damping factor to bring the old woofers (original factory before I overhauled the lower end) under control. It worked like gang busters. I sold the Marantz for a few dollars more than I paid for it.
Passive crossovers provide a natural protection for tweeters. A capacitor in series with a tweeter protects it from frequencies below a certain point. In the case of my AMT3's, there's also a fuse in the mix (some purists hate fuses) that was popped when an old amp went berzerk. That 80 cent fuse was easier to take than an 80 dollar diaphragm. When you bypass the crossover components and hook a tweeter directly to an amp, even one that's only being fed the high frequencies from the active crossover, you still run the risk of the occasional -THUNK- that can be caused by any number of electrical phenomena. Or, in my case, a catastrophic equipment malfunction. The hard core biampers would think me a wienie too scared to squeeze that little extra bit of performance out of a speaker, but as I pretty much scratch by exercising another of the hobbies for a living, the pockets aren't deep enough to take the risk.

I'm jealous of the XSP-1. That thing would fill out the hole in my stereo tower much better than the XDA-1.

I use a "Protection Cap" in a Active Electronic XO that I'm running to protect the Great Heil". I also use a .5 amp fuse in line. Much cheaper than new Diaphragms for sure.
In fact I use 2 amp fuses to protect the woofers and mids in a Tri- amp setup.
 
essNeff - what size (uF) of capacitor do you use in line with the Heil? I've read that the ultimate is to passively cross over at a value a couple octaves out of the range covered by the active crossover. In the case of the tweeter, it would be two octaves below the crossover point. If you were actively crossing over at 2000, the cap would be 80uF, which would be a first order crossover point of 500.That's probably adequate protection, but if you wanted to actively cross over lower than 2000 and wanted to maintain that two octave rule, the protection level would get too low.
The theory behind the two octave rule is that it pretty much keeps the passive function from interfering with the active function - the passive components that the hard-core biampers would sooner avoid are, for all intents and purposes, taken out of the loop.
 
Those are Theta .001 Film/Foil Bypass Caps.
I did bypass caps as well, and like you I did it all at once, which I regret. I was considering doing one without the bypass caps and then A/B'ing them to see if I could tell the difference, but I also hate tearing things apart more than I have to. I figured, other than a few extra dollars, what could be the drawback of bypass caps?
 
Time for an update! Here are some cabinet pics I took tonight. FTR, THIS is why I dis-assembled the finished product. I needed to sharpen the corners:

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And, a fourth coating:

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I've heard some talk that ESS was still selling some new/old stock for a song.
I may be one of the few to give a thumbs up to an Emotiva amp for vintage speakers. I like the idea of a giant transformer and a buttload of capacitance

I'm jealous of the XSP-1. That thing would fill out the hole in my stereo tower much better than the XDA-1.

Yes, I've met Ricky, new ESS CEO, on several occasions. I've been to the new shop in shltty LA warehouse numerous times, all positive experiences I might add (On one occasion, my dad bought the new AMT center channel, to compliment his AMT Monitor fronts and AMT-1c rears in HT setup). That's when I learned of the new-old stock, and that is when I bought the new-old stock ESS 2241-AM active, electronic crossover. It is fixed at 800hz crossover point, though it does have 10db knobs for both low/high freqs. Also, I got to witness first hand the new-old stock Transar (OMG!!!!), a mini-Transar prototype (OMG!!!!!), and several other AMT'ish projects.

As for Emo, I'm a fan. I bought and loved a UMC-1 when it wasn't popular, and currently own and love an XMC-1 and XPA-5 (I got on the pre-order list pretty early, paid $1200) in my home theater upstairs.

I looked at the XDA-1 + amp, but ultimately decided to take the long, slow road. It's why I have an XSP-1 and a $34 Parts Express DIY amp. :dunno:

I have no complaints on the XSP-1. You need it.

I use a "Protection Cap" in a Active Electronic XO that I'm running to protect the Great Heil". I also use a .5 amp fuse in line. Much cheaper than new Diaphragms for sure.
In fact I use 2 amp fuses to protect the woofers and mids in a Tri- amp setup.

I am fascinated by this talk, but I need pictures! And then words explaining the pictures!

essNeff - what size (uF) of capacitor do you use in line with the Heil? I've read that the ultimate is to passively cross over at a value a couple octaves out of the range covered by the active crossover. In the case of the tweeter, it would be two octaves below the crossover point. If you were actively crossing over at 2000, the cap would be 80uF, which would be a first order crossover point of 500.That's probably adequate protection, but if you wanted to actively cross over lower than 2000 and wanted to maintain that two octave rule, the protection level would get too low.
The theory behind the two octave rule is that it pretty much keeps the passive function from interfering with the active function - the passive components that the hard-core biampers would sooner avoid are, for all intents and purposes, taken out of the loop.

This is kinda blowing me away. I think I know the words and what they mean, but not how they look on a crossover board. :idea:
 
Lets just say for the sake of conversation that I snuck into essNeff's house and snapped a picture of the back of one of his AMT's and DID NOT drink his liquor or take any liberties with any of the women sleeping there at the time. Here's what he has:

FirstOrderHeil.jpg

The hot (positive) wire to his tweeter does not come from the crossover. It comes directly from his amplifier, which has a cat sleeping on it, by the way. Before it gets to the heil, it's interrupted by/has to pass through a capacitor. The capacitor filters out frequencies below a certain value depending on the value of the capacitor (in MicroFarads - uF - for speakers, pretty much). Thus, if this was an 80 uF capacitor, nothing below 500 would be able to get to the tweeter at full strength. It's lower frequecies that damage tweeters, so capacitors are wired in a way to provide them with protection. The lower the value in microfarads of the capacitor, the higher the bottom of the range of frequency can get through. A 40 uF cap. would block out everything below 1000. A single cap on a tweeter is a first order/six decibel per octave crossover.
 
essNeff - what size (uF) of capacitor do you use in line with the Heil? I've read that the ultimate is to passively cross over at a value a couple octaves out of the range covered by the active crossover. In the case of the tweeter, it would be two octaves below the crossover point. If you were actively crossing over at 2000, the cap would be 80uF, which would be a first order crossover point of 500.That's probably adequate protection, but if you wanted to actively cross over lower than 2000 and wanted to maintain that two octave rule, the protection level would get too low.
The theory behind the two octave rule is that it pretty much keeps the passive function from interfering with the active function - the passive components that the hard-core biampers would sooner avoid are, for all intents and purposes, taken out of the loop.

I am using 45uf as seen by the 2 NPE's in the pictures. I've been experimenting with XO points and slopes so I figured 45uf @ 900hz or so would give me some room.
I have the Alpha 6A and the Heil crossed @ 1500hz for now 3rd order Butterworth.
I have 2db cut on the Alpha's and 1.5db cut on the Heil.
 

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Lets just say for the sake of conversation that I snuck into essNeff's house and snapped a picture of the back of one of his AMT's and DID NOT drink his liquor or take any liberties with any of the women sleeping there at the time. Here's what he has:

View attachment 653643

The hot (positive) wire to his tweeter does not come from the crossover. It comes directly from his amplifier, which has a cat sleeping on it, by the way. Before it gets to the heil, it's interrupted by/has to pass through a capacitor. The capacitor filters out frequencies below a certain value depending on the value of the capacitor (in MicroFarads - uF - for speakers, pretty much). Thus, if this was an 80 uF capacitor, nothing below 500 would be able to get to the tweeter at full strength. It's lower frequecies that damage tweeters, so capacitors are wired in a way to provide them with protection. The lower the value in microfarads of the capacitor, the higher the bottom of the range of frequency can get through. A 40 uF cap. would block out everything below 1000. A single cap on a tweeter is a first order/six decibel per octave crossover.

Very similar to what I thought.
It's not so easy to sneak into my house though..............IMG_0818.JPG
 
I am using 45uf as seen by the 2 NPE's in the pictures. I've been experimenting with XO points and slopes so I figured 45uf @ 900hz or so would give me some room.
I have the Alpha 6A and the Heil crossed @ 1500hz for now 3rd order Butterworth.
I have 2db cut on the Alpha's and 1.5db cut on the Heil.
I assume that you lowered the levels with resistors when you refer to a decibel cut.
equivalentnomalcrossovercircuit.gif
Why not an L-Pad?
lpad3.gif
 
Finished sanding. Cleaned up. Vacuumed. Applied one coat flat-black paint via foam brush. Looks like I'm going to need several coats. :whip:

Happy Thanksgiving!

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Finished sanding. Cleaned up. Vacuumed. Applied one coat flat-black paint via foam brush. Looks like I'm going to need several coats. :whip:

Happy Thanksgiving!
You've got your work cut out for you. That old presto log will drink up a ton of paint. I had to glaze mine a bit with thin joint compound and quite a bit of primer. Did I mention the wet sanding between coats and the large number of coats that made me miss my labor day deadline. It was a great exercise of the patience that finally seems to be getting better with age. Keep on working it until you're truly happy with the results.

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I used Sandable primer, Black or Dark Gray, Plastic filler (Bondo)
Satin Black Lacquer. I Clear coated just the top with Satin clearcoat.IMG_0772.JPG
If you spray, pull the Xo's with the knobs, mask off the lower cabinet and block the speaker cutouts with cardboard or Rosin paper.

Nice job so far..............I hope you don't get ADDICTED!!!!!!!!!!!!!!
 

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Lets just say for the sake of conversation that I snuck into essNeff's house and snapped a picture of the back of one of his AMT's and DID NOT drink his liquor or take any liberties with any of the women sleeping there at the time. Here's what he has:

View attachment 653643

The hot (positive) wire to his tweeter does not come from the crossover. It comes directly from his amplifier, which has a cat sleeping on it, by the way. Before it gets to the heil, it's interrupted by/has to pass through a capacitor. The capacitor filters out frequencies below a certain value depending on the value of the capacitor (in MicroFarads - uF - for speakers, pretty much). Thus, if this was an 80 uF capacitor, nothing below 500 would be able to get to the tweeter at full strength. It's lower frequecies that damage tweeters, so capacitors are wired in a way to provide them with protection. The lower the value in microfarads of the capacitor, the higher the bottom of the range of frequency can get through. A 40 uF cap. would block out everything below 1000. A single cap on a tweeter is a first order/six decibel per octave crossover.

But isn't this what my active crossover does? To an extent. I mean, both amps go into the active crossover (800hz), one here, one there. Should I open up my new-old stock active crossover, see what's inside? Replace some shlt?

I am using 45uf as seen by the 2 NPE's in the pictures. I've been experimenting with XO points and slopes so I figured 45uf @ 900hz or so would give me some room.
I have the Alpha 6A and the Heil crossed @ 1500hz for now 3rd order Butterworth.
I have 2db cut on the Alpha's and 1.5db cut on the Heil.

Jeebus, what kinda homebrew is THIS? Is it entirely homemade?

I assume that you lowered the levels with resistors when you refer to a decibel cut.
View attachment 653785
Why not an L-Pad?
View attachment 653786

I like where this is going, but I don't quite understand it on first look. If I study it, I see things, but I'm not sure I see all the things.

On a side/related note, one of the reasons why I like the AMT-1a over my AMT Monitors is the mid-range brilliance L-Pot knob. In non-scientific butt-dyno cases, I like the way it sounds more than my Monitors without it. Though, if I bi-amp, that wouldn't really matter, huh?

You've got your work cut out for you. That old presto log will drink up a ton of paint. I had to glaze mine a bit with thin joint compound and quite a bit of primer. Did I mention the wet sanding between coats and the large number of coats that made me miss my labor day deadline. It was a great exercise of the patience that finally seems to be getting better with age. Keep on working it until you're truly happy with the results.

View attachment 653942

On my knees for this one. Those motor boards looks incredible. I hope I can get close to that.

I did not primer. I'm using flat black paint, applied via foam brush. Last night, I did the first coat. Tonight, I did a heavy sanding with 320 grit, then a second coat. When that dried, I did a third coat, no sanding in between. I think tomorrow I'll do a light sanding then fourth coat. Second coat had me worried, but third coat is coming together very nicely. I think I'm headed in the right direction.

I used Sandable primer, Black or Dark Gray, Plastic filler (Bondo)
Satin Black Lacquer. I Clear coated just the top with Satin clearcoat.View attachment 654056
If you spray, pull the Xo's with the knobs, mask off the lower cabinet and block the speaker cutouts with cardboard or Rosin paper.

Nice job so far..............I hope you don't get ADDICTED!!!!!!!!!!!!!!

I left the XOs in on this run, but I've painter's taped the knobs. I'm getting very excited for how good it looks.

Addicted? I've got two rolls of Walnut veneer sitting next to me... And, I haven't even begun playing with the AMT Monitors! :beatnik:
 
But isn't this what my active crossover does? To an extent. I mean, both amps go into the active crossover (800hz), one here, one there. Should I open up my new-old stock active crossover, see what's inside? Replace some shlt?


I like where this is going, but I don't quite understand it on first look. If I study it, I see things, but I'm not sure I see all the things.

On a side/related note, one of the reasons why I like the AMT-1a over my AMT Monitors is the mid-range brilliance L-Pot knob. In non-scientific butt-dyno cases, I like the way it sounds more than my Monitors without it. Though, if I bi-amp, that wouldn't really matter, huh?
If you biamp with the same method that the monitors had you doing it, with the amplifier bypassing the entire crossover, your Heil is unprotected from the whims of an amp. essNeff has a capacitor inline on the positive wire of the heil to give it some protection. He's also got a .5 amp fuse. The capacitor would be a bit of proactive protection while the fuse would be reactive. Your existing crossover could probably be fitted with a switch that could leave your high-pass capacitor in place for bi-amping.
With bi-amping, all L-Pads, potentiometers and rotary resistor switches become irrelevant. You may want to look into an electronic crossover like essNeff has (or the competition). They do just about everything under the sun: crossover (pick your order), equalize, correct phase, etc. These crossovers could easily adjust for the phase (timing) shift induced by putting a protective capacitor in place that the Elite crossover may not.
I'd say you could do some of the same stuff with the higher end home theater receivers with assignable amps and biamping functionality, but, like a lot of us, you've been bitten by the Emotiva bug.
If you don't know the update status of the capacitors and resistors in your passive crossover, it's always a good idea to replace them. 25 years is a good life for a capacitor and yours are pushing 40. If you plan on bi-amping, replace your caps with the same electrolytic capacitors that are in there as you won't be using them much.
 
quite a bit of primer. Did I mention the wet sanding

primer, Black or Dark Gray, Plastic filler

Went to 320, then 400, then 600, and got a near-mirror shine. So hopeful. Why do you build me up Buttercup, baby, just to let me down and mess me around?

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So. Here I go. Gonna scrape it all down again with the heavy stuff. Primer like I should have in the first place. Then sand and wet sand.

Addicted? Yes, I'm in it for the long haul. I've basically decided to sell all my other speakers (AMT Monitors, Klipsch Forte I w/Crites goodies) and focus on perfecting these.

Anyone have any info on those German-made AMT-1e bi-amp'able crossovers? :rolleyes::biggrin:
 
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