Howdy everyone,
I have a pair of old ESS AMT-5 speakers that I'd like to improve reworking/changing the crossover and/or adding a mid driver.
I know, they are not very good speakers.
But they have been purchased almost 50 years ago when I was born by my father & grandfather.
For me, they have an immense sentimental value.
They have been with me since ever; I started listening to music with them and they are still today my PC bookshelf speakers.
The woofer suspension foam, like I believe almost all very first AMT-5, got rotten about 25-30 years and my father got them replaced.
Not sure what was put in but they are still working very well, I assume same or equivalent to the original.
Unfortunately, the only person with actual deep knowledge in Europe about the AMT-5 was Mr. Hoffmann and he passed away last year.
I've been an idiot, I've been living a few kilometers from him for years and I always postponed the call.
I knew he was doing often a rework adding a mid driver with excellent results.
Can only blame myself, carpe diem...
It would be great if someone with knowledge of the Hoffmann's mod could share the details, maybe I could try to do it by myself.
But I don't have much hope to find someone that actually did it and knows the details. It's a very long shot...
I also don't have much free time to spare for such a project.
What I'd like to do in the short term is to rework/replace the crossover.
It has been always quite bad and clearly the components are in a messy state of degradation after almost 50 years...
As a quick win I'd like to just replace it with an already assembled crossover, like a Dayton.
But I don't remember so much, last time I've built a speaker was almost 30 years ago.
I'm not sure what could be right or not.
I see that mostly all these crossovers, if they support 4 Ohm, it's only on the woofer.
The Heil AMT tweeter is, for what I've read, a 4 Ohm.
I've seen some other tweeters, also AMT, and they are all 8 Ohm.
Not sure if I'm wrong but I have the impression these crossovers are meant for 8 Ohm tweeters.
Also I don't know if it could be better to move the crossover point from the original 1500 Hz or keep it.
And if it could be moved a little bit higher, up to which point?
I use them in a small room at a very very conservative volume level.
Any help would be really appreciated 🙂
Otherwise my backup would be to just take out the original crossover and replace the original components with something new and better.
But I'd really like much more the quick win solution and then plan how to make them 3-way.
Thanks a lot in advance!
I have a pair of old ESS AMT-5 speakers that I'd like to improve reworking/changing the crossover and/or adding a mid driver.
I know, they are not very good speakers.
But they have been purchased almost 50 years ago when I was born by my father & grandfather.
For me, they have an immense sentimental value.
They have been with me since ever; I started listening to music with them and they are still today my PC bookshelf speakers.
The woofer suspension foam, like I believe almost all very first AMT-5, got rotten about 25-30 years and my father got them replaced.
Not sure what was put in but they are still working very well, I assume same or equivalent to the original.
Unfortunately, the only person with actual deep knowledge in Europe about the AMT-5 was Mr. Hoffmann and he passed away last year.
I've been an idiot, I've been living a few kilometers from him for years and I always postponed the call.
I knew he was doing often a rework adding a mid driver with excellent results.
Can only blame myself, carpe diem...
It would be great if someone with knowledge of the Hoffmann's mod could share the details, maybe I could try to do it by myself.
But I don't have much hope to find someone that actually did it and knows the details. It's a very long shot...
I also don't have much free time to spare for such a project.
What I'd like to do in the short term is to rework/replace the crossover.
It has been always quite bad and clearly the components are in a messy state of degradation after almost 50 years...
As a quick win I'd like to just replace it with an already assembled crossover, like a Dayton.
But I don't remember so much, last time I've built a speaker was almost 30 years ago.
I'm not sure what could be right or not.
I see that mostly all these crossovers, if they support 4 Ohm, it's only on the woofer.
The Heil AMT tweeter is, for what I've read, a 4 Ohm.
I've seen some other tweeters, also AMT, and they are all 8 Ohm.
Not sure if I'm wrong but I have the impression these crossovers are meant for 8 Ohm tweeters.
Also I don't know if it could be better to move the crossover point from the original 1500 Hz or keep it.
And if it could be moved a little bit higher, up to which point?
I use them in a small room at a very very conservative volume level.
Any help would be really appreciated 🙂
Otherwise my backup would be to just take out the original crossover and replace the original components with something new and better.
But I'd really like much more the quick win solution and then plan how to make them 3-way.
Thanks a lot in advance!
The old AMT tweeters in those loudspeakers are very good, if not rotten away while stored away in some mouldy basement for years.
Actually I have been listening to a pair for more than 15 years and they survivied many other tweeters in my setup, including the big heil, Raal ribbons and literally every dome tweeter I have ever tried. But, there is a big but. They are in no way capable of playing down to 1500Hz without massive distortion. There natural response drops down fast below 2.5- 3kHz. I have been using them from 3500Hz on up with 60db/oct filters and that's about the limit of what they can do before distortion kicks in. Adding a mid driver is the best you can do I guess but that also makes crossover tuning a lot more difficult. Mine measure a straight 6 ohm, so if taken the natural roll-off into account at least the tweeter part of the crossover in not that hard. I would use steep filters though. Avoid any output below 2500 Hz (as in at least 10dB down at that point) and you'll be fine. Can't comment on the woofers nor on the enclosure as I have never heard them and I don't want to speculate, I only have experience with those tweeters and they are worth it to keep.
Actually I have been listening to a pair for more than 15 years and they survivied many other tweeters in my setup, including the big heil, Raal ribbons and literally every dome tweeter I have ever tried. But, there is a big but. They are in no way capable of playing down to 1500Hz without massive distortion. There natural response drops down fast below 2.5- 3kHz. I have been using them from 3500Hz on up with 60db/oct filters and that's about the limit of what they can do before distortion kicks in. Adding a mid driver is the best you can do I guess but that also makes crossover tuning a lot more difficult. Mine measure a straight 6 ohm, so if taken the natural roll-off into account at least the tweeter part of the crossover in not that hard. I would use steep filters though. Avoid any output below 2500 Hz (as in at least 10dB down at that point) and you'll be fine. Can't comment on the woofers nor on the enclosure as I have never heard them and I don't want to speculate, I only have experience with those tweeters and they are worth it to keep.
Thanks a lot for your answer!
As I said, I just love these speakers 🙂
Luckily both me and my father managed to keep them always in a good order.
The tweeters are still in perfect shape after 48 years of service and I bet they can do another 50 without a hitch 😛
I will open the enclosure one of these days and try to find out what is the woofer inside but I fear it'll be impossible to get any info about it...
Therefore I think I'll have to dive blind on the crossover.
I've read as well that it'd be better to go above 3.5 kHz to avoid distortion.
I'd really like to add a mid but it's a long term goal.
The original crossover is known to be using bad quality components and a bad design, already in '74...
Would like to just buy a simple assembled crossover and see if I'm lucky and works better than the old one.
Then I could have time to re-work the original one while still using the speaker.
Problem is all the assembled 2-way crossovers I can find around have the high pass at 8 Ohm, only the low pass can be set at 4 Ohm.
Like this one which is cheap and quite commonly available in Europe:
https://www.soundimports.eu/en/dayton-audio-xo2w-3k.html
Now I'm trying to re-learn everything I forgot in the last 30 years about crossovers but it's though...
I'm surprised yours measured 6 Ohm... I've read they should be 4 Ohm and the few measurements I've found online were reporting 4.5 Ohm.
As I said, I just love these speakers 🙂
Luckily both me and my father managed to keep them always in a good order.
The tweeters are still in perfect shape after 48 years of service and I bet they can do another 50 without a hitch 😛
I will open the enclosure one of these days and try to find out what is the woofer inside but I fear it'll be impossible to get any info about it...
Therefore I think I'll have to dive blind on the crossover.
I've read as well that it'd be better to go above 3.5 kHz to avoid distortion.
I'd really like to add a mid but it's a long term goal.
The original crossover is known to be using bad quality components and a bad design, already in '74...
Would like to just buy a simple assembled crossover and see if I'm lucky and works better than the old one.
Then I could have time to re-work the original one while still using the speaker.
Problem is all the assembled 2-way crossovers I can find around have the high pass at 8 Ohm, only the low pass can be set at 4 Ohm.
Like this one which is cheap and quite commonly available in Europe:
https://www.soundimports.eu/en/dayton-audio-xo2w-3k.html
Now I'm trying to re-learn everything I forgot in the last 30 years about crossovers but it's though...
I'm surprised yours measured 6 Ohm... I've read they should be 4 Ohm and the few measurements I've found online were reporting 4.5 Ohm.
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This is the only "datasheet" I could find online:
By the way, they go down to 40 Hz and I've never managed to make them work at 4 Ohm - only 8 Ohm.
By the way, they go down to 40 Hz and I've never managed to make them work at 4 Ohm - only 8 Ohm.
What I figured so far is:
Found out the SoundImports is selling the DATS V3 for a decent price here in Europe.
Looks really like a nice gadget to have for such a low price.
Then I tried to understand how to measure the drivers frequency response and I got lost...
I have read the manual of DATS V3 and still don't understand if it can measure frequency response.
It almost looks like it does it but SoundImports is clearly stating it doesn't.
In the manual there's a reference about using an external Mic for measurements but it's not very clear...
There's also no mention about Mic calibration data.
In the additional features is stating:
"1 Hz - 20,000 Hz Response, Measures any Loudspeaker Driver, Including Tweeters"
Maybe it's just talking about impendence. Not sure.
Anyway I see that mostly REW is used to generate the frequency response file.
Which brings a lot of other questions and doubts.
First is that I have no idea yet on what is the setup for the measurement.
From what I have found around seems the driver is connected directly to the amp with a volume set to output 2,83V measured with the DMM.
Or a fixed volume at a specific SPL but don't really seems logical...
I hope someone can explain the procedure cause I couldn't find any info about it.
The other problem seems to be the Mic to use with REW.,
I have a USB miniDSP UMIK-1 and while someone is using it for years without any issue seems it's not a really good idea.
From my understanding since it's USB the lack of the feedback channel could cause problems with phase detection.
I have also a Dayton Audio IMM 6 which is analogic but I'm not sure it's a good idea to use it for this purpose...
Maybe I can use it to cross check the phase detection with the UMIK-1?
Not really deep enough yet in... still unclear to me what should I exactly do in REW.
- Finding a proper 2-way assembled crossover is very unlikely
- To change the crossover frequency of the original crossover without messing up I need to use XSIM and thus I need the frequency response and impendence files (ZMA and FRD) for the woofer and the tweeter. Which I'll never find.
- Even more so if I later want to make the speakers 3-way, I need the ZMA and FRD
- I also suspect that even in the unlikely case that I find the right files would be better to make my own measurements since these drivers are almost 50 years old
Found out the SoundImports is selling the DATS V3 for a decent price here in Europe.
Looks really like a nice gadget to have for such a low price.
Then I tried to understand how to measure the drivers frequency response and I got lost...
I have read the manual of DATS V3 and still don't understand if it can measure frequency response.
It almost looks like it does it but SoundImports is clearly stating it doesn't.
In the manual there's a reference about using an external Mic for measurements but it's not very clear...
There's also no mention about Mic calibration data.
In the additional features is stating:
"1 Hz - 20,000 Hz Response, Measures any Loudspeaker Driver, Including Tweeters"
Maybe it's just talking about impendence. Not sure.
Anyway I see that mostly REW is used to generate the frequency response file.
Which brings a lot of other questions and doubts.
First is that I have no idea yet on what is the setup for the measurement.
From what I have found around seems the driver is connected directly to the amp with a volume set to output 2,83V measured with the DMM.
Or a fixed volume at a specific SPL but don't really seems logical...
I hope someone can explain the procedure cause I couldn't find any info about it.
The other problem seems to be the Mic to use with REW.,
I have a USB miniDSP UMIK-1 and while someone is using it for years without any issue seems it's not a really good idea.
From my understanding since it's USB the lack of the feedback channel could cause problems with phase detection.
I have also a Dayton Audio IMM 6 which is analogic but I'm not sure it's a good idea to use it for this purpose...
Maybe I can use it to cross check the phase detection with the UMIK-1?
Not really deep enough yet in... still unclear to me what should I exactly do in REW.