ESS AMT 10b Woofer Recommendation.
- Thread starter Bon Rener
- Start date
Or instead of all the messing around, get the original
3 way that ESS MADE.
Put some decent woofers in it
Brace and dampen cabinet
Recap with Mundorfs or the like.
Regrill with cool Mojotone and enjoy one of the finest vintage speaker out there!
These seem to be the current hot ticket in AMT3 woofer upgrades.......
https://www.parts-express.com/dayton-audio-rs270p-8a-10-reference-paper-woofer-8-ohm--295-579
He ran them sealed, not vented.
Damping all the walls with foam-especially the back panel is critical-along with the recommended bracing between the driver openings.
Lpad the mid (if aftermarket) and Heil with the new 4ohm units to fine tune.
For the price of admission, and when done right-it's hard to find that musical, detailed-big wide open full range sound that for many stops your speaker journey..
Hehe, except for those pesky open baffle Heils...
Hopefully Misco will finally decide to make a 8 ohm version of the Legacy woofer.
Classic American pulp cone-poly ether-wide open sound-would be a perfect replacement-as Porkloin mentioned-modern methods-modern materials....
Oh well!
Last edited:
Puppet,
Recognize that for some people.
And, then there are those who think they can hear a mouse fart at 50 yards, through a vacuum, and tell you if it off-key. Some of them have ears so well calibrated and a music memory so long that they have no need of reference if they wish to make a change and can easily remember what circuit/combination provided what fraction of a dB cut or boost at what frequency so that they can go back too it.
Then there are those with hearing so good that they can hear "nothing."
And of course we all know about how, with one exception, the people in the kingdom complemented the Emperor on his "new clothes."
Last edited:
Puppet,
Recognize that for some people.
And, then there are those who think they can hear a mouse fart at 50 yards, through a vacuum, and tell you if it off-key. Some of them have ears so well calibrated and a music memory so long that they have no need of reference if they wish to make a change and can easily remember what circuit/combination provided what fraction of a dB cut or boost at what frequency so that they can go back too it.
Then there are those with hearing so good that they can hear "nothing."
And of course we all know about how, with one exception, the people in the kingdom complemented the Emperor on his "new clothes."
Your form of truth?
Hmmm....I thought you were "done with me"?!
I'm seeing your form of truth quite clearly now.....+2 likes
!And as far as hearing nothing-you guys clearly aren't reading my posts-I'm not saying your not hearing anything.
So talking about some form of truth's, truth seekers, makes little sense here-except band wagon perhaps. It's all good.....
Example Heil peaks, valleys etc. (Although over the Internet I'm skeptical).
Even if I was skeptical on your measurement methods-(that had more to do how it applied to my own listening space then anything else) I never recall denying your personal results.( Although some past professional speaker w/Great Heils reviews have not to came to the exact same conclusion here-but I get the issue your pointing out.
It's not like your breaking any ground here-it's been talked about for decades.
The weight in your conclusions was what I took issue with.
Like anything in life-some people take issues with things-some don't.
Same with audio.
It's that simple.
How one interprets reality of their system into personal audio enjoyment.
The system as a whole-not just the individual parts.
And as a analogy, I could clearly say they same thing in reverse, the clothes-there ain't nothin there cat...better grab a towel!!
The rest you may be reading between the lines something that I never intended to say-if you misunderstood that-my apologies.
I figured it was obvious-my bad.....
Taking friendly banter personally, as mentioned before-might look at your own responses before throwing stones..
But I get it-this forum vs in person-it's too easy to focus on one or two words, a simple sentence, and take it out of context. No worries...
As far as proofs/truths on my AMT3 Mojo mods (the goal always was making it easy for the average Joe to improve their AMT3's with simple tools, methods etc not a large investment in tools, etc-things that were not focused directly on improving the speakers) -I get are from those feedback from other members I was able to help...or start on their own journey...pretty cool stuff!
Last edited:
automojo, I'll admit I got a chuckle out of toddalin's post w/Jack Nicholson ... bet you did, too.
You tweak for sound quality, I get that and that's cool. I and others go after the frequency response anomalies. If you worked that into your mod's ... well, look out. I know these diaphragms can be a mixed bag when it comes to frequency response. For me, flattening that out makes integrating them with other drivers that much simpler.
I've gone so far as to tweak the diaphragms themselves to help improve the response eg. taking off the veils, adding silicone @ tops/bottoms of the frames and lucky for me this has helped tame a couple of "wild" responses. The silicone application was touch and go. At first I thought I wrecked the sensitivity. I did the mod and after a couple hours put the diaphragm back measured the response and it was down 6-8db SPL. Thought I pooched it. Brought the amp level for that driver back up and let it play a few hours resigning myself to having to order another pair. Came back the next day and after firing up the system that diaphragm sounded real bright. Dragged out the gear and sure enough, 8db to hot. Looked like the silicone needed to fully cure to not effect the sensitivity but in the process it also flattened out a 7khz peak by 3db and another @2.5khz by 1-2db. I've said this before, I think a little more attention to detail on the assembly (@FACTORY) could improve diaphragm to diaphragm response. That could make the integration for the end user so much more comparable, as well as factory crossover work. They aren't there yet so, we adjust with EQ or other means.
Just like your mods ... it's just about overall sound quality. Not a waste of time as far as I'm concerned. My arrangement takes the rear wave out of the equation. Tweeter/room interaction is minimal as it's now more constant directivity, like a horn. Others will want to block the back wave output, adjust the response flat and then treat the room to tame the back wave reflections. The end results should be quite similar then. Try it out.
Rock on brother!
You tweak for sound quality, I get that and that's cool. I and others go after the frequency response anomalies. If you worked that into your mod's ... well, look out. I know these diaphragms can be a mixed bag when it comes to frequency response. For me, flattening that out makes integrating them with other drivers that much simpler.
I've gone so far as to tweak the diaphragms themselves to help improve the response eg. taking off the veils, adding silicone @ tops/bottoms of the frames and lucky for me this has helped tame a couple of "wild" responses. The silicone application was touch and go. At first I thought I wrecked the sensitivity. I did the mod and after a couple hours put the diaphragm back measured the response and it was down 6-8db SPL. Thought I pooched it. Brought the amp level for that driver back up and let it play a few hours resigning myself to having to order another pair. Came back the next day and after firing up the system that diaphragm sounded real bright. Dragged out the gear and sure enough, 8db to hot. Looked like the silicone needed to fully cure to not effect the sensitivity but in the process it also flattened out a 7khz peak by 3db and another @2.5khz by 1-2db. I've said this before, I think a little more attention to detail on the assembly (@FACTORY) could improve diaphragm to diaphragm response. That could make the integration for the end user so much more comparable, as well as factory crossover work. They aren't there yet so, we adjust with EQ or other means.
Just like your mods ... it's just about overall sound quality. Not a waste of time as far as I'm concerned. My arrangement takes the rear wave out of the equation. Tweeter/room interaction is minimal as it's now more constant directivity, like a horn. Others will want to block the back wave output, adjust the response flat and then treat the room to tame the back wave reflections. The end results should be quite similar then. Try it out.
Rock on brother!
acres
Come on-we aren't teen agers that need tippy toes now are we?
Talk about childish behavior- he might want to rethink his position on that one...read his own post in realistic context...most actual adults have the ability of self reflection. and delineate responses and bits of information in context to their responses and the subject matter.....whatever..
I get it... the current flavor of the day....dish it out....but play wounded when the recipient..in a nutshell...
So with that in mind/hindsight, I was a bit too harsh..and can do the kids gloves when needed in the future...whatever..
Puppet, I appreciate your contributions to the Heil forums, and keep them in the memory banks.
There is a huge difference between challenging, and discounting observations and opinions.
Yep I agree on the vibrations as well-good stuff.
Not to mention controlling noise, which not only includes clean power but the aforementioned vibrations.
Any of these in combination or by themselves can certainly emphasize certain frequencies, particularly in the higher octaves.
You may be correcting something that could be corrected by a better means!
The first gen housings are obviously resonate. I've applied foam and putty to the "V" voids with good success-seems to tame the audible issues I was having. And use a different rubber composition base.
I also use the Amazon cork bases Stereophile used on their review of the new Klipsch Forte's-since I now have a wood floor listening room.
https://www.amazon.com/BXI-Vibratio...ild=1&keywords=bxi+cork&qid=1597367180&sr=8-1
Nothing like sealed bass and the Great Heil!!
I didn't have much luck with the triangle lens on the old housings-just wasn't a good mix
At some point I will log some video measurements to confirm the strange dispersion characteristics, and the increase in db right of the housing.
Moving them out simply blocked the detail.
Same with the time alignment-wasn't audible in two completely different listening rooms. One well dampened-the other fairly reflective.
I agree on the value of flattening response curves-as a general rule-that's pretty much a given-but as a point of emphasis-end all be all-that certainly depends on if you truly understand in a auditory sense the pluses and minus of what your doing. And not simply looking at a ruler flat response cure-and saying "thats it!".
Other simply cross it 2000hz on up-but IMHO you loose a lot of the Heil magic coming from a single source in the critical midrange.
Again I bring up the stock AMT3..even with the low crossover point...HF found it had at the time one of the flatter response curves.
The stock speaker sounds very good-I have zero issues mids on up-one of the best I have heard. The exception was the stock woofers.
What ever the peak/dips-it doesn't seem to be much a issue with the AMT3-I can't recall anyone ever mentioning it-just the lack of deep clan bass with the stock woofers.
Pretty simple.
Ethel Mermans be damned!!
We must all have lying' ears...
I didn't bother with measurements-preferred my families and audio buddies ears.
All are extremely familiar with this system-it's used easily 6-10 hours daily-better half works at home.
A working mans/family audio system so to speak....plenty of baseline to go on.
And lets face it-most people modding their AMT3's-don't have the equipment anyway.
My mods were set up for the average Joe Audio wanted to improve his AMT3's
That's the essence of the Mojo Modded AMT3's.
Seems to have benefited more then a few, from what I can tell...
Again-thanks for the clarification-much appreciated!!
I only have experience with the 2 new diaphragms-I may get a second pair when I get the Mojo 3.1's up and running.
I certainly have zero problem with this first set
We are all seeking the same thing-just a bit different routes-but if you analyze it carefully-they are more similar then different.
Thanks cool cat.....much appreciated.....and catch ya on side "b"!......
Yes-of course I did too-life is way to short to wear your emotions and self worth on your sleeve.automojo, I'll admit I got a chuckle out of toddalin's post w/Jack Nicholson ... bet you did, too.
You tweak for sound quality, I get that and that's cool. I and others go after the frequency response anomalies. If you worked that into your mod's ... well, look out. I know these diaphragms can be a mixed bag when it comes to frequency response. For me, flattening that out makes integrating them with other drivers that much simpler.
I've gone so far as to tweak the diaphragms themselves to help improve the response eg. taking off the veils, adding silicone @ tops/bottoms of the frames and lucky for me this has helped tame a couple of "wild" responses. The silicone application was touch and go. At first I thought I wrecked the sensitivity. I did the mod and after a couple hours put the diaphragm back measured the response and it was down 6-8db SPL. Thought I pooched it. Brought the amp level for that driver back up and let it play a few hours resigning myself to having to order another pair. Came back the next day and after firing up the system that diaphragm sounded real bright. Dragged out the gear and sure enough, 8db to hot. Looked like the silicone needed to fully cure to not effect the sensitivity but in the process it also flattened out a 7khz peak by 3db and another @2.5khz by 1-2db. I've said this before, I think a little more attention to detail on the assembly (@FACTORY) could improve diaphragm to diaphragm response. That could make the integration for the end user so much more comparable, as well as factory crossover work. They aren't there yet so, we adjust with EQ or other means.
Just like your mods ... it's just about overall sound quality. Not a waste of time as far as I'm concerned. My arrangement takes the rear wave out of the equation. Tweeter/room interaction is minimal as it's now more constant directivity, like a horn. Others will want to block the back wave output, adjust the response flat and then treat the room to tame the back wave reflections. The end results should be quite similar then. Try it out.
Rock on brother!
Come on-we aren't teen agers that need tippy toes now are we?
Talk about childish behavior- he might want to rethink his position on that one...read his own post in realistic context...most actual adults have the ability of self reflection. and delineate responses and bits of information in context to their responses and the subject matter.....whatever..
I get it... the current flavor of the day....dish it out....but play wounded when the recipient..in a nutshell...
So with that in mind/hindsight, I was a bit too harsh..and can do the kids gloves when needed in the future...whatever..
Puppet, I appreciate your contributions to the Heil forums, and keep them in the memory banks.
There is a huge difference between challenging, and discounting observations and opinions.
Yep I agree on the vibrations as well-good stuff.
Not to mention controlling noise, which not only includes clean power but the aforementioned vibrations.
Any of these in combination or by themselves can certainly emphasize certain frequencies, particularly in the higher octaves.
You may be correcting something that could be corrected by a better means!
The first gen housings are obviously resonate. I've applied foam and putty to the "V" voids with good success-seems to tame the audible issues I was having. And use a different rubber composition base.
I also use the Amazon cork bases Stereophile used on their review of the new Klipsch Forte's-since I now have a wood floor listening room.
https://www.amazon.com/BXI-Vibratio...ild=1&keywords=bxi+cork&qid=1597367180&sr=8-1
Nothing like sealed bass and the Great Heil!!
I didn't have much luck with the triangle lens on the old housings-just wasn't a good mix
At some point I will log some video measurements to confirm the strange dispersion characteristics, and the increase in db right of the housing.
Moving them out simply blocked the detail.
Same with the time alignment-wasn't audible in two completely different listening rooms. One well dampened-the other fairly reflective.
I agree on the value of flattening response curves-as a general rule-that's pretty much a given-but as a point of emphasis-end all be all-that certainly depends on if you truly understand in a auditory sense the pluses and minus of what your doing. And not simply looking at a ruler flat response cure-and saying "thats it!".
Other simply cross it 2000hz on up-but IMHO you loose a lot of the Heil magic coming from a single source in the critical midrange.
Again I bring up the stock AMT3..even with the low crossover point...HF found it had at the time one of the flatter response curves.
The stock speaker sounds very good-I have zero issues mids on up-one of the best I have heard. The exception was the stock woofers.
What ever the peak/dips-it doesn't seem to be much a issue with the AMT3-I can't recall anyone ever mentioning it-just the lack of deep clan bass with the stock woofers.
Pretty simple.
Ethel Mermans be damned!!
We must all have lying' ears...
I didn't bother with measurements-preferred my families and audio buddies ears.
All are extremely familiar with this system-it's used easily 6-10 hours daily-better half works at home.
A working mans/family audio system so to speak....plenty of baseline to go on.
And lets face it-most people modding their AMT3's-don't have the equipment anyway.
My mods were set up for the average Joe Audio wanted to improve his AMT3's
That's the essence of the Mojo Modded AMT3's.
Seems to have benefited more then a few, from what I can tell...
Again-thanks for the clarification-much appreciated!!
I only have experience with the 2 new diaphragms-I may get a second pair when I get the Mojo 3.1's up and running.
I certainly have zero problem with this first set
We are all seeking the same thing-just a bit different routes-but if you analyze it carefully-they are more similar then different.
Thanks cool cat.....much appreciated.....and catch ya on side "b"!......
Last edited:
Last edited:
Hi ! you mean that the secret for getting great sound is in flattening the FR ? that is interesting. I am a little worried about reflected sounds ... there could be a sort of echo effect in the listening position
Lately having to use my desktop pc for smart working
i have also decided to improve the pc audio system Even with ridiculously cheap speakers i have been impressed by the good soundstage that can be obtained listening nearfield. I have seen pics of recording engineers listening pretty close to the speakers for i guess editing their masters ... maybe the solution is in eq the FR and listening in the nearfield ?Actually a scaled down copy of that ... but i like the woofer enclosure a lot. I am sure that one of those nice big Tannoy coaxials would sound fantastic mounted in a similar enclosure
Actually it is what Tannoy did in the DMT professional series. But they have used coaxials with a strange material for the cones ... some kind of treated plastic ?
Many swear that paper cones sound better ...
When I first build my enclosure I made it with a couple modifications in mind so it was basically convertible. I wasn't sure if the woofer wanted ports as I tend to prefer sealed. The box was made large enough to accommodate porting. I left it sealed so far using a lower shelving EQ option. The bass is tight. The box is overdamped (Q=0.5) but that isn't/wasn't out of the ordinary. The enclosure was flipped over with the heil on top but the struggle with a lively room and higher SPL doomed a full dipole arrangement. Like toddalin mentioned a few times, I tried a partial muffling of the rear side but couldn't find the right combination. I listen to everything and some genre like the "ambiance" of the rear wave but most don't, just MO.
At any rate, sometimes a guy gets something in his head and out comes the saw. I suppose I could flip it back and make a separate enclosure for the heil above ... "Volti" style. It would resemble the fine pic's you posted. .... thanks for that ginetto61 (grrrr)
GL with your build!
I am sure that your creation would sound fantastic anyway. If the front baffle is big however i would not put the woofer in the center of the baffle and just below it i would fix some bracing to avoid any baffle movement ... i am attaching a cabinet solution that for me is fantastic ... from Energy Veritas series ... that is a great bookshelf indeed. I wonder why it has not been more popular ... an excellent speaker indeed. Never heard
but the feeling that is very good indeed is strong in meKind regards, gino
Flattening but not flat... otherwise it will sound dull and lifeless.
A minidsp with Dirac Live is a better choice then REW-even with the mini.
more sophisticated and versatile and uses non phase shifting filters.
Sure, it cost a few hundred, but you can easily spend that on cables, or other stuff that doesn’t have the same impact
A minidsp with Dirac Live is a better choice then REW-even with the mini.
more sophisticated and versatile and uses non phase shifting filters.
Sure, it cost a few hundred, but you can easily spend that on cables, or other stuff that doesn’t have the same impact
Gil hi-fi
New Member
Hello, please i need a help, i am more or less in the same situation with my pair of ESS amt10b without passive radiator at the rear version.
Here in France 10" ESS 689-1010 woofer model is available at the official ESS store distributor and also ESS in US' recommended me by mail this same model but my speakers are a different or very old version with a original and completely round hole adapted for those mentioned woofers but not really esthetically adapted! The frame are not the same please watch this picture, actually with a replaced Italian woofers from Ciare 251HW, well adapted they are, sound is not bad and certainly not denatured of the ESS sound but of course not at 100%
Wath better to do ?
*sorry for the poor english
Here in France 10" ESS 689-1010 woofer model is available at the official ESS store distributor and also ESS in US' recommended me by mail this same model but my speakers are a different or very old version with a original and completely round hole adapted for those mentioned woofers but not really esthetically adapted! The frame are not the same please watch this picture, actually with a replaced Italian woofers from Ciare 251HW, well adapted they are, sound is not bad and certainly not denatured of the ESS sound but of course not at 100%
Wath better to do ?
*sorry for the poor english
Attachments
Last edited:
ratskins
Member
I'm sitting here right now looking my ESS AMT10bs. The cones are a black plastic material . . . not paper. I had another pair I got new around 1980. They had the same cones. These speakers are fantastic, but you may have to experiment with room placement and finding the right spot for the dial on the back that attenuates the air motion transformer. It's easy to make them too bright. Dispersion from left to right is good, but dispersion up and down is not nearly as wide. You'll want to make sure you are in the blast zone.
Agreeded..
Bextrine.
State of the art at the time.
The vertical dispersion was intentionally limited to prevent ceiling reflections.
This dispersion works better in a larger room than a smaller one.
Frankly, the smaller monopole Heil works , much better in smaller rooms, like the Emits.
Love the Great Heil though, even with its drawbacks.
Just my opinion, sealed bass works the best…ESS loved BR bass boxes.
It’s too bad they really didn’t concentrate on developing a higher output 10 and 12 inch woofer that would’ve been sufficient (output) with a single Drive unit.
Last edited:
Aethelstan
Active Member
Reviving this thread because I am considering replacing the original woofers. I am looking for advice. My main problem is that I keep getting inconsistent data from my research. (links in blue) What say ye, Audiokarma?
Hi Fi Engine lists the ESS AMT-10b at 6 ohms, 90db sensitivity, 40-22k freq resp. Xover 1400. The actual data sheet posted at Hi Fi Engine says 6 ohm, 92db, 50-22k fr., Xover 1500. My ears think the latter is more likely.
My preliminary woofer replacement options are:
Dayton 255-8 - 8 ohm, 92.6db, 46-3.5k fr, 50.7 Fs, .39 Qts) ~$70 ea
MCM 55-1215 - spec sheet says 8 ohm, 88+/-2 db, 34.9Fs, .587 Qts (website says 8 ohm, 94db, 30 Fs, .53 Qts) ~$34 ea.
MCM 55-1250 - spec sheet says 8 ohm, 90+/-2 db, 40.7 Fs, .74 Qts (website says 8 ohm, 94db, 35 Fs, .58 Qts) ~$22 ea.
I am leaning toward the MCM 55-1215. The Qts seems a bit high for a ported speaker, but the ESS AMT-10b don't seem like typical ported speakers. The port seems folded like a quasi-mini-transmission line speaker. I am also guessing that the sensitivity rating for that speaker might be ok the original speaker was 6 ohm.
But what's with the varying specs? Confusing.
Hi Fi Engine lists the ESS AMT-10b at 6 ohms, 90db sensitivity, 40-22k freq resp. Xover 1400. The actual data sheet posted at Hi Fi Engine says 6 ohm, 92db, 50-22k fr., Xover 1500. My ears think the latter is more likely.
My preliminary woofer replacement options are:
Dayton 255-8 - 8 ohm, 92.6db, 46-3.5k fr, 50.7 Fs, .39 Qts) ~$70 ea
MCM 55-1215 - spec sheet says 8 ohm, 88+/-2 db, 34.9Fs, .587 Qts (website says 8 ohm, 94db, 30 Fs, .53 Qts) ~$34 ea.
MCM 55-1250 - spec sheet says 8 ohm, 90+/-2 db, 40.7 Fs, .74 Qts (website says 8 ohm, 94db, 35 Fs, .58 Qts) ~$22 ea.
I am leaning toward the MCM 55-1215. The Qts seems a bit high for a ported speaker, but the ESS AMT-10b don't seem like typical ported speakers. The port seems folded like a quasi-mini-transmission line speaker. I am also guessing that the sensitivity rating for that speaker might be ok the original speaker was 6 ohm.
But what's with the varying specs? Confusing.
Aethelstan
Active Member
I didn't really consider the ESS option. Just wanted more bass.
Now that I look, the only ESS option goes down to 45Hz (Fs at 27Hz)... and costs $90 ea... but ESS Factory 10″ Woofer 689-1010 – ESS Speakers USA
I am a little confuse about why the bottom of the reported frequency response is so much higher than the Fs.
Now that I look, the only ESS option goes down to 45Hz (Fs at 27Hz)... and costs $90 ea... but ESS Factory 10″ Woofer 689-1010 – ESS Speakers USA
I am a little confuse about why the bottom of the reported frequency response is so much higher than the Fs.
Last edited:
Aethelstan
Active Member
So... After some reflection, I think replacing the 4 ohm woofer with an 8 ohm woofer is viable here and may even improve the AMT-10b's performance compared to using ESS's replacement woofer.
First, using an 8ohm woofer instead of a 4 ohm woofer would put less stress on the amp.
Second, the spec sheet says the AMT-10b is 92db, but the replacement woofer is only 90.6. An 8 ohm woofer will operate 3db higher than a 4 ohm woofer at the same power level. So an 88 db 8 ohm woofer, like the MCM 55-1215. should operate closer to the spec sheet db rating than ESS's replacement woofer. Granted, the differences - 1db or less - are likely inaudible. In any case, I am actually ok with the tweeter being a bit louder than the woofer either way given that I like speakers to be a bit more forward.
Third, this leaves open the issue of crossover frequency. As a 6 ohm speaker - presumably a 4 ohm woofer and an 8 ohm tweeter - the original set up crosses over at 1500Hz. Swapping in an 8 ohm woofer should move the woofer's crossover frequency to 3000 Hz, assuming there is a coil in the crossover. (Not sure about the amt-10b, but every ESS amt crossover pic I have seen has a coil,) This means the tweeter crossover point needs to also rise to 3000Hz. One of the Heil tweeter's advantages was its ability to reach unusually low frequencies without degradation, but does that matter as long as the crossover frequency range is relatively smooth? I don't think so, and the clarity of a modern woofer in that 1500-3000 Hz range might exceed that of the 45-year old tweeter anyway. The MCM 55-1215 appears to do a good job in that range too, better than the MCM 55-1250, which has a peak at 3000. I have not seen the amt-10b's crossover, but I am guessing the cap is in the 18-30uf range. So, replacing that capacitor with one with half of the original capacitance (maybe 9-15uf) should do the trick.
What am I missing here?
First, using an 8ohm woofer instead of a 4 ohm woofer would put less stress on the amp.
Second, the spec sheet says the AMT-10b is 92db, but the replacement woofer is only 90.6. An 8 ohm woofer will operate 3db higher than a 4 ohm woofer at the same power level. So an 88 db 8 ohm woofer, like the MCM 55-1215. should operate closer to the spec sheet db rating than ESS's replacement woofer. Granted, the differences - 1db or less - are likely inaudible. In any case, I am actually ok with the tweeter being a bit louder than the woofer either way given that I like speakers to be a bit more forward.
Third, this leaves open the issue of crossover frequency. As a 6 ohm speaker - presumably a 4 ohm woofer and an 8 ohm tweeter - the original set up crosses over at 1500Hz. Swapping in an 8 ohm woofer should move the woofer's crossover frequency to 3000 Hz, assuming there is a coil in the crossover. (Not sure about the amt-10b, but every ESS amt crossover pic I have seen has a coil,) This means the tweeter crossover point needs to also rise to 3000Hz. One of the Heil tweeter's advantages was its ability to reach unusually low frequencies without degradation, but does that matter as long as the crossover frequency range is relatively smooth? I don't think so, and the clarity of a modern woofer in that 1500-3000 Hz range might exceed that of the 45-year old tweeter anyway. The MCM 55-1215 appears to do a good job in that range too, better than the MCM 55-1250, which has a peak at 3000. I have not seen the amt-10b's crossover, but I am guessing the cap is in the 18-30uf range. So, replacing that capacitor with one with half of the original capacitance (maybe 9-15uf) should do the trick.
What am I missing here?
Aethelstan
Active Member
Hmmm... Am I mistaken in thinking that the coil handles the top end of the woofer (i.e., low pass filter) and the capacitor handles the bottom end of the tweeter (i.e., high pass filter)?
