Whats broke here?

I am corresponding with a guy that is refurbing AMT1's with a 10" Pro woofer with 96 db sensitivity in hopes of bridging the infamous ESS midrange gap..The bad is, he'll be lucky to hit 50 Hz, meaning he'll be using a subwoofer. Do you want to be part of that messaging thread to pick up potential driver inspiration?
Human Speakers (no affiliation) is making a 10" woofer now. It may be an option.

http://www.humanspeakers.com/diy/parts/031.htm
 
Human Speakers (no affiliation) is making a 10" woofer now. It may be an option.

http://www.humanspeakers.com/diy/parts/031.htm
Those look like the answer to an ESS refurb guy's prayers. They go plenty low for the small AMT1 enclosure volume, but I suppose it's asking too much for a driver that can overlap the Heil's usable range enough to avoid the infamous mid-range gap at the same time. I'm watching the project of RickHouTX's in which he's using a highly sensitive pro driver that won't go anywhere that low, but it's upper end extends an octave into the Heil's actual usable range. He's counting on needing a subwoofer, but I'm betting the end product's low end will be nothing to scoff at.
 
Those look like the answer to an ESS refurb guy's prayers. They go plenty low for the small AMT1 enclosure volume, but I suppose it's asking too much for a driver that can overlap the Heil's usable range enough to avoid the infamous mid-range gap at the same time. I'm watching the project of RickHouTX's in which he's using a highly sensitive pro driver that won't go anywhere that low, but it's upper end extends an octave into the Heil's actual usable range. He's counting on needing a subwoofer, but I'm betting the end product's low end will be nothing to scoff at.
I used a pair of his 8" woofers in my ESS PS-8's. I am extremely pleased with how it worked out.

http://audiokarma.org/forums/index.php?threads/ess-refurbishment.411841/#post-8839509
 
Ok, hoping you guys can tell me whats going on here. I've attached a bunch of photos of the hi pass crossover from what I thought was the working speaker from these AMT 2's. I don't work on crossovers or know what is right or wrong, but i see several things here that makes me wonder if someone was in here mucking around.

Some of the things I notice right away are that one of rhe coils is not atrached to anything. One of the caps has only one lead. One of rhe ceramic resistors is connected ro nothing and is where one of the two wires connecting it to the low pass filter block are coming in.

Also, what is the purpose of the two little rubber things on the end of those wires?

Is this thing even doing anything?

I want to restore this back to factory, so if anyone has any info on what this should look like or the schematics, I would appreciate it.

Help!
 

Attachments

  • 20170324_120451.jpg
    20170324_120451.jpg
    78.3 KB · Views: 29
  • 20170324_120441.jpg
    20170324_120441.jpg
    83.6 KB · Views: 24
  • 20170324_120415.jpg
    20170324_120415.jpg
    80.6 KB · Views: 23
  • 20170324_120406.jpg
    20170324_120406.jpg
    82.4 KB · Views: 21
  • 20170324_120316.jpg
    20170324_120316.jpg
    87 KB · Views: 21
  • 20170324_120300.jpg
    20170324_120300.jpg
    87.7 KB · Views: 23
  • 20170324_122336.jpg
    20170324_122336.jpg
    44 KB · Views: 25
Last edited:
Nearly all vintage speakers that I come upon have had somebody muck around with them. That sure is a mess. Hopefully the other speaker is better. But getting hold of a schematic is the only sure way of restoring that. I do not know what those black spacers (insulators?) are for
 
Good point Bob. I suppose it would be rare to find one that hadn't, but I'm an optimist. :)

Unfortunately, the other one is the one is in the same shape, if not worse. Maybe between the two, I can figure out what normal should be. I'll peal it out too and post some pics of what I find.

I wonder if the rubber things are the the blown out ends of a cap? Never pulled one apart.

Good news is that the low pass boards are pristine, but much simpler.
 
With all the ESS stuff posted at AK, surely someone has a schematic you can go off of. I did not see one in a quick search of the Interwebz.
 
Last edited:
With all the ESS stuff posted at AK, surely someone has a schematic you go off of. I did not see one in a quick search of the Interwebz.

Agreed...however I'm having zero luck finding anything. I called ESS today and they pointed me to a PDF they have with a schematic for every crossover except for, you guessed it, the AMT 2.

He said that I could send them in and for 45 bucks a piece, they would rebuild them.

If I could find the schematics, i think I could do it cheaper, so still hoping something shows up.
 
Ok...I mapped the "good" crossover. Even on this one, one of the two leads coming from the main board flies off into nothing after a resistor.

20170324_222841.jpg

Thoughts on where that lead would comnect into the rest? After that, does this look legit?

Most things were there and connected. I did find that the little rubber things on the other crossover were indeed remnants of a capicitor. Wonder what these things have been through to get in this shape...
 
Well this board isn't going to do diddly without that second lead hooked up to anything. But this appears to be a crossover, all right. :biggrin: We could help you sort it out with a bit more info.

What does the 'main board' look like? Does it have any components or just the main input connectors?

And, where are all the connections to the drivers? Presumably they come off of this board you have drawn out.
 
After rereading your post above with the xover pics, it sounds like the other board has a low-pass section for the woofer and then the remaining signal goes to this board. So I assume the mid/tweeter are connected to this board. If you can point out where, that will help in reformatting your wiring diagram into a standard crossover schematic. [Edit: which will then apparently be the only example of an AMT2 schematic on the web, where other people can find it.]
 
Here's a link to what appears to be some scans of a bunch of documents from ESS. I don't think the 2 is in there, but you may be able to establish a pattern. Yours may have more in common with the Original AMT-1 (no letter designation) than they do with the later letter designation as I don't believe that the 2's had a midrange presence knob on them.
 

Attachments

  • ESS_AMT_1B_Crossover.jpg
    ESS_AMT_1B_Crossover.jpg
    51.9 KB · Views: 8
  • ESS_AMT_1C_Crossover.jpg
    ESS_AMT_1C_Crossover.jpg
    56.9 KB · Views: 6
Worst case scenario, you copy any of the 2-way models with the great Heil as there's no big differences between the drivers themselves. The changes appear to be more an evolution in crossover philosophy over the years. I would trust those as a reference more so than the slightly hinky ones you have at the moment.
 
Well this board isn't going to do diddly without that second lead hooked up to anything. But this appears to be a crossover, all right. :biggrin: We could help you sort it out with a bit more info.

What does the 'main board' look like? Does it have any components or just the main input connectors?

And, where are all the connections to the drivers? Presumably they come off of this board you have drawn out.

Here is the main/low pass board...

20170330_233427.jpg
 
Worst case scenario, you copy any of the 2-way models with the great Heil as there's no big differences between the drivers themselves. The changes appear to be more an evolution in crossover philosophy over the years. I would trust those as a reference more so than the slightly hinky ones you have at the moment.

Hey guys, I appreciate all the input on this! However, I think I'm going to send one in and have it rebuilt (I know I'm lazy :D). Then I can use that for reference to rebuild the other. 50 bucks and I will know its to spec. and a good template for the other. I will definately post the result as this appears to be little documetation model.

Thanks again for all the help!
 
I'm confused about the "main board" thing. The board pictured is a complete two-way second order crossover. The value of the woofer parallel cap looks a little low
 
Hey guys, I appreciate all the input on this! However, I think I'm going to send one in and have it rebuilt (I know I'm lazy :D). Then I can use that for reference to rebuild the other. 50 bucks and I will know its to spec. and a good template for the other. I will definately post the result as this appears to be little documetation model.

Thanks again for all the help!
50 bucks? Send them both in and be done with it.
 
Back
Top Bottom