Jimbro - if these were from any of the original AMT1 family, the drivers themselves were quite good - in fact the tweeter is still a world class device - recently "reissued", and quite worth the asking price, and the woofer did a pretty respectable job of trying to keep up - however the cabinets and particularly the crossovers were a joke. Keep in mind that these were introduced during the heyday of the big gas SS amp and receiver wars and it wasn't uncommon to see them driven to clipping with 150WPC or more - "Just because we can, dude" . If you've ever looked at the quality of components and needless complexity of the XO, it's not hard to understand how in conjunction with all that power the ribbons could get overdriven. IINM the current models & replacement diaphrams have been ruggedized, albeit at the expense of minor sacrifice in sensitivity and dynamics / HF extension.
Now, streamline the XO (biamp particularly) and run the AMT with that nice little 3-5 watt tube amp, and it's a whole 'nother freakin barbeque
Part of the problem. aside from clipping, is running the Heil too low.
The use of a transiton driver, crossing over to the Heil around 2500 is the only way to go IMHO-exactly what the ESS AMT3 did. The Heil is now in it's ideal range.
The AMT3 is the best desgn ESS produced, and when properly refurbed, resealed, and recapped will give most speakers a serious run for their money-the imaging and detail is amazing.
I have had Great heils for years- those diaphrams are hard to blow, unless you bypass the fuse, and drive your amp into clipping/DC.
The fuse doesn't effect the sound one bit-I have experimented many times-can't hear any difference period-so keep them fused, or don't over drive them.
Easy to do, as they play so clear-with little compression-so it's hard to tell your taxing your amp.
An ideal modern AMT3 would be to take 2 Eminence/OCS 1040SF's, or perhaps a Audax PR240MO, operating in a 3.0 Cu ft enclosure.
The woofers crossing over to a Audax HM130CO driver at around 500 to 750 hz, and the Audax Crossong over to the Heils @2500hz.
2 way designs with a 6 1/2 to 8 inch woofers, are better then the larger 2 way designs as far as midrange/midbass reponase goes (i.e. hole)-but you are really defeating your ourpose by running a low efficiency woofer-thus having to excessivley pad the Heil to achieve frequency balance.
The use of a transiton driver, crossing over to the Heil around 2500 is the only way to go IMHO-exactly what the ESS AMT3 did. The Heil is now in it's ideal range.
The AMT3 is the best desgn ESS produced, and when properly refurbed, resealed, and recapped will give most speakers a serious run for their money-the imaging and detail is amazing.
I have had Great heils for years- those diaphrams are hard to blow, unless you bypass the fuse, and drive your amp into clipping/DC.
The fuse doesn't effect the sound one bit-I have experimented many times-can't hear any difference period-so keep them fused, or don't over drive them.
Easy to do, as they play so clear-with little compression-so it's hard to tell your taxing your amp.
An ideal modern AMT3 would be to take 2 Eminence/OCS 1040SF's, or perhaps a Audax PR240MO, operating in a 3.0 Cu ft enclosure.
The woofers crossing over to a Audax HM130CO driver at around 500 to 750 hz, and the Audax Crossong over to the Heils @2500hz.
2 way designs with a 6 1/2 to 8 inch woofers, are better then the larger 2 way designs as far as midrange/midbass reponase goes (i.e. hole)-but you are really defeating your ourpose by running a low efficiency woofer-thus having to excessivley pad the Heil to achieve frequency balance.
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or for that matter the stock woofers and PR from AMT1, Eminence Beta6 midrange, and a new enclosure designed to emulate the originals - for customer who'd just spent the best part of $400 having surrounds replaced all 4 active and passive drivers and grilles rebuilt.
An externally hosted image should be here but it was not working when we last tested it.
XO design by others courtesy LMS measures and LEAP modeling
It's easy to gain a db or 2 of sensitivity, plus lower your ESR by substituting quality poly caps, and large gauge inductors with the stock crossover. Unless your refering to the 4 coil Zobel network with the early design AMT3-the later 3 coild design in very straight foward-and fairly simple-and also rely's on the generious overlaps of the stock drivers.
The cabinet can be improved by a few basic items-sealing and strengthening.
ESS now has reissues for the AMT1 10" and 12" driver. AS for the AMT3 the 1040SF is the closest you will find to the stock woofer-a modern equivilent that keeps up a bit better then the stock Alnico's woofer did-but mind you the 1040SF's output is about even with the Heil-instead of 2-3db down-so in that respect the 'voicing" will change.But if you recharge the Alnio'x you will come close. The 1040SF is similiar to the stock woofer, in that in rolls of smoothly, and lacks a impendnence peak, typical of a lot of today's drivers.
The Alpha^A is a great substitute for the stock foam surround driver-but may need to be adjusted via a l-pad or resistor for the earlier desing that used the 4 coil Zobel and Peerless rubber surround transition/mid driver.
The cabinet can be improved by a few basic items-sealing and strengthening.
ESS now has reissues for the AMT1 10" and 12" driver. AS for the AMT3 the 1040SF is the closest you will find to the stock woofer-a modern equivilent that keeps up a bit better then the stock Alnico's woofer did-but mind you the 1040SF's output is about even with the Heil-instead of 2-3db down-so in that respect the 'voicing" will change.But if you recharge the Alnio'x you will come close. The 1040SF is similiar to the stock woofer, in that in rolls of smoothly, and lacks a impendnence peak, typical of a lot of today's drivers.
The Alpha^A is a great substitute for the stock foam surround driver-but may need to be adjusted via a l-pad or resistor for the earlier desing that used the 4 coil Zobel and Peerless rubber surround transition/mid driver.
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Having heard the 7.3 I think it would make a good little monitor(or midrange) but I have a pair of RAAL 20-xr ribbons and would love if someone could work up a 24db low pass crossover at 1800hz so I could try my little experiment...any help appreciated as I have no design experience or measuring equipment other than my ears.
Hi Wallacefl, the beauty of the Acoustic Reality design is its simplicity; capacitorless, low parts count and first order-ish. Doing so preserves the single driver sound more or less. A proper 24db crossover is going to take a lot of parts and may very well suck the life out of the 7.3. Perhaps, an electronic low pass might be an easier propostion with added eq flexibility.
Or... Why not use the RAAL, which is reputedly not easy to blow up, in the AR crossover schema? You could half the value of the series coil to the 7.3 and crossover the RAAL an octave higher. Then adjust the R values by listening. Just don't turn it up too loud! Some may disagree, but your ears are your best tool.
No doubt the RAAL is a marvelous device, but having heard the 7.3 a fair bit myself, I can't help but think out loud as to why you'd want to cross them over as low as 1800? While they (7.3) can definitely benefit from HP and support woofers, the range from 400-6400 is where I consider these to most particularly excel, and in any case even with an extremely well implemented XO of any alignment, 1800 - 2600 or so would be the range I'd go out of my way to avoid for turnover point - particularly with drivers likely to have substantially different polar radiation patterns in the bracketing octaves.
Chris's point about crossing-over is important. Low mass full-rangers (assuming the designer's done his/her homework) should be at optimal when used full-range or near full range in an optimsed box. Most of the passive filters I've heard are negatively audible on sensitive cones. Active filtering might possibly offer a better solution.
A note on using large woofs and subs. Most are good for generating pistonic LF frequency but rarely emit the micro-resonances necessary to create discernible music to a descent standard. The large mass of their power-train inhibits and/or prevents micro-resonant emission.
I like to encourage more Diyers to consider designing boxes to get the most out of the single point source full-ranger. My perspective is purist for which I make no apology. Granted Full-Rangers are limited to lower power applications, but we should ask ourselves how much power and consumption do we really need. We humans seem hell-bent on making everything bigger, heavier, being determined to eat up resources and cripple the planet. Yet take a look at Graham's set up in New Zealand, you'll see a pair of Pensil 12's in a massive high ceiling room, easily putting out enough sound to please even those who want laud; All done with 2 Alp12's (stereo), simple box design and a moderate powered tube amp: http://hifi.goneill.co.nz/
Will I make another woofer and tweeter, likely yes but My main focus is that full-range drivers could replace more multiway systems in the future. We owe it to our kids, families, friends and future generations to make better use of resources by trying to do more with less.
Thanks
Mark.
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I applaud the effort, research, engineering, and common sense approach of Mr. Fenlon. A superior SD in an optimized enclosure, with a (relatively) low powered (tube) amp is a joy to hear.
My 10.2's in Dave's Mar-ken cabs, driven by 8 wpc. of single-ended power are very satisfying indeed.
Thanks for the ever evolving product line!
Don
My 10.2's in Dave's Mar-ken cabs, driven by 8 wpc. of single-ended power are very satisfying indeed.
Thanks for the ever evolving product line!
Don
I applaud Mark's sentiment there, but tinkering is personally irresistible on the path to finding my own DIY Nirvana. I originally messed around with adding a second hand homeless tweeter to make my A7.3s more user friendly while I was breaking them in and to try the capacitor-less crossover. I was amazed at how close to greatness the lash-up came.
Since then I have alternated between running the A7.3s with and without the ER4. The ARSXO crossover just provided too little attenuation for the tweeter and it started to show its fundamental resonance quack at moderate volumes, so I now (a little modelling and a lot of tweaking, measuring and listening later), I have a 5KHz 2nd order LR-ish parallel network in place which is putting me on the horns of a dilemma.
The A7.3 naked is remarkable in its resolution but for me it can't quite match the hugely expensive ER4 in the treble where I'm very fussy. But adding the crossover and tweeter does remove a little, and I mean a little: not a lot, of the coherence of the single driver. So as I suspected, there is never a free lunch, but I've had some fun and learned a lot. The real bonus is I now have great sounds in my office while I work.
Which do I think is better? Which will I stick with? I've no idea.
Since then I have alternated between running the A7.3s with and without the ER4. The ARSXO crossover just provided too little attenuation for the tweeter and it started to show its fundamental resonance quack at moderate volumes, so I now (a little modelling and a lot of tweaking, measuring and listening later), I have a 5KHz 2nd order LR-ish parallel network in place which is putting me on the horns of a dilemma.
The A7.3 naked is remarkable in its resolution but for me it can't quite match the hugely expensive ER4 in the treble where I'm very fussy. But adding the crossover and tweeter does remove a little, and I mean a little: not a lot, of the coherence of the single driver. So as I suspected, there is never a free lunch, but I've had some fun and learned a lot. The real bonus is I now have great sounds in my office while I work.
Which do I think is better? Which will I stick with? I've no idea.
Hello Simon,
Glad your experimenting. I've found a little time to look at this thread (not as much as I'd like). Bear in mind I'm less than a stone's throw from several ribbon makers (I have some on my bench), be aware for allot of tweets, its a fine-line between "actual sound" reproduction and distortion in the ranges you describe.
I wouldn't normally recommend any audiophile to add a tweet (of any type) to a driver the likes of Alpair 7 Gen.3. Given its wide range (close to 30-kHz) and dispersion, in a good box mated to a descent amp and accurate source, the Alps will emit near faithful reproduction to the original source.
Aging engineers like Me, Ted Jordan et.al increasingly lament the gradual dumbing down of "High Fidelity" (being acoustically faithful to the original source). 2 way and multi-way systems, while can be good, split the emitted range and with phase differentials, create an "artificial" sound. Since these systems have been dominant in the market place for so many years, we've become assimilated to their output. This doesn't mean all split systems are bad. Indeed, I have a fondness for Victor SX 500 Spirits as I own 2 pairs in mint condition that do a nice job:
VICTOR ƒXƒs�[ƒJ�[ƒVƒXƒeƒ€SX-500‚ÌŽd—l ƒrƒNƒ^�[
I encourage most experimentation. Indeed, its why I made the effort with the CHP's and CHBW's because I appreciate that not everyone is "purist". Colin's forthcoming Rossendales project with CHBW's and a ribbon should be very interesting:
http://www.diyaudio.com/forums/markaudio/212074-4-x-chbw-rbt95sq-ribbon-tweeter.html
Summarising, your idea of adding a tweet is based on personal taste that I suspect has been influenced by the audio market over the years. That doesn't mean its a mistake, but we all should be aware of system design limitations and those influences that bear down on driver/system design. For those who wish to remain purist, keep the system simple.
I'll continue doing my best to remain within the bounds of original High-Fidelity, while trying to accommodate Diyer's desires.
Cheers
Mark
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How about taking the AR cross schema and applying the highpass to the A7.3 instead and using some wide bandwidth woofer? One could tweak the values so that you are crossing around 250Hz or so and thus relieving the A7.3 from the heavy lifting, albeit at 1st order slopes. I've high passed a few "full rangers" before and all have improved mids and highs.
AR XO is a specific instance of a series XO. One would be ahead just starting from scratch.
dave
The problem with using the OEM Raal 20xr is that the crossover is sort of designed into the driver and I have no idea of how to get around this. What I would really like to do is use it LR 12db cut at about 7000hz but I do not have measuring equipment/etc so I am open for any suggestions. Thanks
7.3
I personally think the top end is absolutely fine, I would like to reduce the bottom end of the 7.3 as some low frequencies on particular recordings can catch them out at moderate listening levels. This is in a sealed cab of around 8L. I would like to build a bookshelf/standmound with a 8-10 inch woofer, but not sure where to cross them for the best?
I personally think the top end is absolutely fine, I would like to reduce the bottom end of the 7.3 as some low frequencies on particular recordings can catch them out at moderate listening levels. This is in a sealed cab of around 8L. I would like to build a bookshelf/standmound with a 8-10 inch woofer, but not sure where to cross them for the best?
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