Found the order and part numbers. In the 2nd round I used the foil inductors for both filter sections.
Description | Unit price | Qty | Amount |
Solen 20uF 400V Polypropylene Capacitor Item# 027-582 | $9.25 USD | 4 | $37.00 USD |
1.2mH 14 AWG Perfect Layer Inductor Item# 266-355 | $28.18 USD | 2 | $56.36 USD |
Jantzen 7835 1.2mH 16 AWG Copper Foil Inductor Item# 255-632 | $28.16 USD | 2 | $56.32 USD |
There are non polarized electrolytics you can buy. Solen has them. Mouser and digikey have them as well. They are constructed internally like you say.
Pretty much every vintage crossover I encounter has bipolar electrolytics.
I was referring to the schematic in post #4, that is sourced from the document in post #13.
I'm taking a look at yours too, but I see it is for a 12" woofer not a 10" one.
You can use those values for the 10 inch woofer as well.
If you have the AMT-1 with the port on the bottom and want to keep the factory crossover point at 600 hz.
Here is a link to some neat crossover tools:
https://www.erseaudio.com/CrossoverCalculators
Attachments
Having been intimate with the development process, I can tell you the factory crossover was more like 800 Hz. ESS was eager to represent the AMT as going lower, but also wanted it to play loud, so a higher frequency won out in reality if not in the promotional literature.
What improvments did you notice in the sound with this variation of the design? Did you find the speakers were well balanced in the midrange?
Looks like a cheaper design to build too.
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Thanks Nelson! Nothing better than knowledge from the one who was there and made it happen.
I pulled the 600 hz from this. Must have been very early - maybe the we haven’t released it yet brochure.
https://audio-database.com/ESS/speaker/amt1-e.html
The 992 cycle crossover did really well for us with the 10” cabinet. The one with the port in the bottom.
Tried every combination there was to try with the 12 inch with the passives on the back and came to the conclusion that the woofer they use must just lose efficiency past 500 cycles.
With the 10 inch woofer the results were pretty amazing. Unfortunately those cabinets were so trashed by the time I got them that one of them fell apart. They were 43 years old by the time I found them on eBay. The crossover components with the biggest audible issues were the L pads. The cap values were still pretty close to right.
To answer your question. The Linkwitz filter was leaps and bounds better than the stock filter. Very “full” and well balanced. In the 10 inch cabinet.
never did get the 12 inch woofer AMT-1C cabinets to mate to the heil with what I’d call outstanding results. It seems that it loses efficiency pretty rapidly past 3 or 400 cycles. It is there but we spent an awful lot of time saying what did he or she say?
Nothing beats the 3 way arrangement in my earlier picture. I’ve never heard the original rock monitor that had the in between driver but imagine it is very similar to what I here out of these.
From what I understand through researching these speakers is balancing the Heil in a 2 way is not an ideal situation.
These are the 10" woofer with the bottom ported cabs.
These are for a client but I've taken a bit of a deeper dive for the sake of interest and learning. And the client is interested in going the best possible route.
That looks to be a later schematic - during my time they used two pole filters.
This is the one I wanted to build, though I'm tempted by tjw59's schematic now.
The original crossover in these is the earlier version with the 20uf and 50uf capacitors. Another variation on that crossover used another 20uf cap instead of the 50uf one. Seems they went through a few iterations.
thank you very much for the information!
Credit where it is due. I wrote to Nelson about 9 years ago and he helped me with the crossover. We are all so fortunate to have the best people and resources. Thanks Nelson!
You said you used the foil inductors for both positions for the second round. Did you use the 16AWG for both positions?
On the first round I used the 16 awg for the woofers. Then switched to the foil for both with the 12 inch project. Then one night - this hit home.
Here are the specs of the 10” woofer. Note the Le = 1.2 uh.
https://essspeakers.store/products/ess-factory-10-woofer
I did and it worked very well.
Why would I do that?
I matched AM broadcast antennas for years. And we always took into account the reactive component of the load.
I never see this talked about anywhere. So one night I took an alligator clip and shorted the inductor. It is kind of blind luck in this instance that the specified inductor is the inductance of the speaker coil. But it is: and it works fine.