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A/D/S/ L1590

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The L1590 was a 1980's speaker held in high regard for its uniform on-axis output as well as it's relatively flat acoustic-power output, the downfall of so many loudspeakers. The acoustic-power frequency response is basically the integrated power output of a transducer as measured throughout a listening environment, and is a measurement of the speaker's abillity to disperse sound over a wide vertical and horizontal axis. The end result was a speaker that was capable of great accuracy and realism, as well as a speaker with very "spacious" sound characteristics.

The L1590 also had very low distortion and excellent deep-bass capability with its two 10-inch acoustic-suspension woofers mounted in separate chambers within the heavily braced cabinet. The -3 dB point of this speaker was approximately 28 Hz, so the low-frequency extension was also excellent. Power-handling for the woofers was top notch with the 2-inch-diameter voice coils with 1.5-inch high windings, giving greater than .5-inch linear overhang.

Subjectively, earlier versions of the tweeter used A/D/S/ was considered to be bright sounding, but A/D/S/ made changes to the crossover and the magnet structures on this vintage of the speaker, and the L1090, L1290 and L1590 were a bit more reticent than earlier models.

--Tom Tyson

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Tom,

I agree--the ADS '90 series were excellent loudspeakers. I came very close to buying a pair of 1290's. I also thought the 1290's somewhat slimmer profile made it a more attractive speaker than the 1590, which was somewhat 'chunky.'

I seem to remember that these speakers had the unusual option of having a power amplifier attached to the rear of the cabinet in a recess that was made to accept an ADS sub amp. So equipped, these ADS speakers had powered 'subwoofers' and passive mids/highs, pre-dating the so-called Powered Towers of Definitive Technology by some 10 or 15 years.

I know I have some lit on these ADS speakers somewhere in my dusty archives, but perhaps you might shed some light on this innovative aspect of their design.

It always struck me as strange that these ADS speakers did not enjoy wider critical acclaim (were any of them reviewed by the Big Three?) or more widespread commercial success.

Steve F

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Tom,

I agree--the ADS '90 series were excellent loudspeakers. I came very close to buying a pair of 1290's. I also thought the 1290's somewhat slimmer profile made it a more attractive speaker than the 1590, which was somewhat 'chunky.'

I seem to remember that these speakers had the unusual option of having a power amplifier attached to the rear of the cabinet in a recess that was made to accept an ADS sub amp. So equipped, these ADS speakers had powered 'subwoofers' and passive mids/highs, pre-dating the so-called Powered Towers of Definitive Technology by some 10 or 15 years.

I know I have some lit on these ADS speakers somewhere in my dusty archives, but perhaps you might shed some light on this innovative aspect of their design.

It always struck me as strange that these ADS speakers did not enjoy wider critical acclaim (were any of them reviewed by the Big Three?) or more widespread commercial success.

Steve F

Dear Steve F,

There were several reviews of this series, and one of the better reviews was on the L1290 by Julian Hirsch. The review pretty much speaks for itself, but suffice it to say, Hirsch-Houck Labs was duly impressed by the speaker! If possible, I will attach a copy of that review in PDF format. It is interesting that the 1290 had a 500 Hz crossover and the 1590 had a 350 Hz crossover -- both using the 2-inch dome midrange. I was told by A/D/S/ back in the 80s that the 1590 version had a lower resonance due to a larger cavity under the dome (both drivers were small acoustic-suspension designs!) and some minor changes to the voice coil, I believe. The midrange did not use ferro-fluid, nor was it fused, but the tweeter used the ferro-fluid and had a thermal-resetting fuse link.

I agree: these were superb loudspeakers, and I owned a pair of 1590s (which I now have back -- see images in prior message) that I bought new. Prior to the 1590s I owned AR-9s; after the 1590s I had KEF R107s, then B&W 801 Matrixes. The 9s had the bottom-end pretty well covered, but not greatly better than the 1590s. The 107s were the best in very deep bass, however, but too directional in the midrange for my tastes, over time. The 801s were great, but the bass was less-well defined than the others. Some of my best memories were of the 1590s!

--Tom Tyson

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Tom,

I agree--the ADS '90 series were excellent loudspeakers. I came very close to buying a pair of 1290's. I also thought the 1290's somewhat slimmer profile made it a more attractive speaker than the 1590, which was somewhat 'chunky.'

I seem to remember that these speakers had the unusual option of having a power amplifier attached to the rear of the cabinet in a recess that was made to accept an ADS sub amp. So equipped, these ADS speakers had powered 'subwoofers' and passive mids/highs, pre-dating the so-called Powered Towers of Definitive Technology by some 10 or 15 years.

I know I have some lit on these ADS speakers somewhere in my dusty archives, but perhaps you might shed some light on this innovative aspect of their design.

It always struck me as strange that these ADS speakers did not enjoy wider critical acclaim (were any of them reviewed by the Big Three?) or more widespread commercial success.

Steve F

Steve F,

Some additional comments on your message above:

ADS did offer a PA1 Biamplifier (module) powered option in 1986 or 1987 that mounted down at the base of the L1290 and L1590 speakers (only). The cost was $1200 (per pair), and I don't think ADS offered the option for very long due to its added cost. By late 1987, with the introduction of the new "Unison" M9, M12 and M15 (equivalent to the older L1590), the power module was not available, to my knowledge, or at least I've never seen one in use with the M12 or M15. It was also at this time that ADS adopted the a/d/s/ logo (which was not used with the original L1290 and L1590 series I and II), and the gradual slide backward had begun although there was a spurt of activity with the "Unisom" M-series and the CM5, CM6 and CM7, all superb and favorably reviewed loudspeakers. Perhaps it was the beginning of the Subsat series and the exotic M20 and hugely expensive M30 that began the slowly downward spiral (as with so many other loudspeaker manufacturers during the late 1980s and into the 1990s).

As for ADS' critical acclaim, there were numerous reviews on the various models (up through and including the Unison series) in most of the major magazines. Nearly all of the reviews were extremely flattering and favorable to ADS, with many exclamations from renowned critics such as Julian Hirsch saying about the L1290, "...the widest and flattest response we can recall measuring from a speaker with our current test procedures." Another reference to the 1290, "the woofer distortion was perhaps the lowest we have yet measured." Hans Fantel in The New York Times said, "...the L1590 is widely regarded as one of the finest loudspeakers ever made." Ovation magazine reviewed the L1090 and gave it very high marks; High Fidelity gave high marks to the single-woofer L990 as did Digital Audio magazine. Hirsch also reviewed the L780 and gave it the same type of excellent review as he did the 1290. These are just some of the reviews that I have in my file; there are probably quite a few more.

--Tom Tyson

The excellent ADS 2-inch dome midrange of the mid 1980s.

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Steve F,

Some additional comments on your message above:

ADS did offer a PA1 Biamplifier (module) powered option in 1986 or 1987 that mounted down at the base of the L1290 and L1590 speakers (only). The cost was $1200 (per pair), and I don't think ADS offered the option for very long due to its added cost. By late 1987, with the introduction of the new "Unison" M9, M12 and M15 (equivalent to the older L1590), the power module was not available, to my knowledge, or at least I've never seen one in use with the M12 or M15. It was also at this time that ADS adopted the a/d/s/ logo (which was not used with the original L1290 and L1590 series I and II), and the gradual slide backward had begun although there was a spurt of activity with the "Unisom" M-series and the CM5, CM6 and CM7, all superb and favorably reviewed loudspeakers. Perhaps it was the beginning of the Subsat series and the exotic M20 and hugely expensive M30 that began the slowly downward spiral (as with so many other loudspeaker manufacturers during the late 1980s and into the 1990s).

As for ADS' critical acclaim, there were numerous reviews on the various models (up through and including the Unison series) in most of the major magazines. Nearly all of the reviews were extremely flattering and favorable to ADS, with many exclamations from renowned critics such as Julian Hirsch saying about the L1290, "...the widest and flattest response we can recall measuring from a speaker with our current test procedures." Another reference to the 1290, "the woofer distortion was perhaps the lowest we have yet measured." Hans Fantel in The New York Times said, "...the L1590 is widely regarded as one of the finest loudspeakers ever made." Ovation magazine reviewed the L1090 and gave it very high marks; High Fidelity gave high marks to the single-woofer L990 as did Digital Audio magazine. Hirsch also reviewed the L780 and gave it the same type of excellent review as he did the 1290. These are just some of the reviews that I have in my file; there are probably quite a few more.

--Tom Tyson

The excellent ADS 2-inch dome midrange of the mid 1980s.

I remember hearing various ADS systems at an audio shop called "Sound Company" in the city where I live. This was around 1979. The impression I still have was that the system had a unique clarity and smoothness that the other offerings were seriously lacking. I think it may have been the model 610. What happened to ADS? I know they are still around as a corporate entity but they seem to be largely peddling auto sound related products. Did they go down the same path as AR, Advent and so on being bought up by companies that sell video tape head cleaners and such?

-T

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I remember hearing various ADS systems at an audio shop called "Sound Company" in the city where I live. This was around 1979. The impression I still have was that the system had a unique clarity and smoothness that the other offerings were seriously lacking. I think it may have been the model 610. What happened to ADS? I know they are still around as a corporate entity but they seem to be largely peddling auto sound related products. Did they go down the same path as AR, Advent and so on being bought up by companies that sell video tape head cleaners and such?

-T

pretty much. Mike Kelly was one of the key people responsible for that ADS sound of the 70's, he started and runs Aerial Acoustics which is responsible for some of the finest sounding speakers made on the planet today.

btw, i'll bet those were the L810's you were listening to.

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What happened to ADS? I know they are still around as a corporate entity but they seem to be largely peddling auto sound related products. Did they go down the same path as AR, Advent and so on being bought up by companies that sell video tape head cleaners and such?

-T

In 2001 a/d/s/ became part of Directed Electronics, a large (and the industry leader) auto-alarm security systems manufacturer based in southern California. Directed Electronics acquired Orion and Precision Power that same year; and since that time the company has been on a steady diet of company acquisitions, including Polk and Definitive Technology, making the company the number supplier of home-theatre loudspeakers, according to their website. Directed Electronics has sales of $400M in 2007, but also had a big loss due to a non-recurring cost. In 2006 the company had sales of $438M and a profit of $21M, approximately. As for a/d/s/, the division produces mainly home-theatre products.

What I don't know is the history of a/d/s/ during the 1990s. I don't know when the company was first sold, but for now a/d/s/ is in good hands.

--Tom Tyson

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The L1590 also had very low distortion and excellent deep-bass capability with its two 10-inch acoustic-suspension woofers mounted in separate chambers within the heavily braced cabinet. The -3 dB point of this speaker was approximately 28 Hz, so the low-frequency extension was also excellent. Power-handling for the woofers was top notch with the 2-inch-diameter voice coils with 1.5-inch high windings, giving greater than .5-inch linear overhang.

One thing that ADS did for service centers was to provide replacement dome assemblies and woofer-cone-voice-coil assemblies that could simply be placed into the magnet assembly with minimum alignment difficulties. The woofer replacement assembly did include a clear cylindrical alignment shim to make sure the coil was properly in place. The dome tweeters were placed down into the ferrofluid already in the gap, thus assuring good alignment once the four centering screws were in place. The precision manufacture of these drivers is amazing! The voice coils are coated with a special dark-gray lacquer coating, but this was later dropped in favor of clear lacquer. The woofer voice coil on the L1590 was 2-inches in diameter, quite large for a ten-inch woofer, and the cone material (referred to as Stiflite) was thick and dense, yet very light. The woofer's coil former, or bobbin, was made from Kapton, a high-temperature Nylon-like material that is ideally suited for that purpose.

--Tom Tyson

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The L1590 was a 1980's speaker held in high regard for its uniform on-axis output as well as it's relatively flat acoustic-power output, the downfall of so many loudspeakers. The acoustic-power frequency response is basically the integrated power output of a transducer as measured throughout a listening environment, and is a measurement of the speaker's abillity to disperse sound over a wide vertical and horizontal axis. The end result was a speaker that was capable of great accuracy and realism, as well as a speaker with very "spacious" sound characteristics.

The L1590 also had very low distortion and excellent deep-bass capability with its two 10-inch acoustic-suspension woofers mounted in separate chambers within the heavily braced cabinet. The -3 dB point of this speaker was approximately 28 Hz, so the low-frequency extension was also excellent. Power-handling for the woofers was top notch with the 2-inch-diameter voice coils with 1.5-inch high windings, giving greater than .5-inch linear overhang.

Subjectively, earlier versions of the tweeter used A/D/S/ was considered to be bright sounding, but A/D/S/ made changes to the crossover and the magnet structures on this vintage of the speaker, and the L1090, L1290 and L1590 were a bit more reticent than earlier models.

--Tom Tyson

Some additional images of the ADS Rosewood L1590:

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I remember hearing various ADS systems at an audio shop called "Sound Company" in the city where I live. This was around 1979. The impression I still have was that the system had a unique clarity and smoothness that the other offerings were seriously lacking. I think it may have been the model 610. What happened to ADS? I know they are still around as a corporate entity but they seem to be largely peddling auto sound related products. Did they go down the same path as AR, Advent and so on being bought up by companies that sell video tape head cleaners and such?

-T

Sorry this is so many months after the original post, but I just came across this today. Perhaps I can shed a little light on your whatever happened to a/d/s/ curiosity. I was employed by a/d/s on two occasions. The first from 1983 - 1993, then from 1996 - 1999, so was in a position to see some of the changes that resulted in the eventual downfall of a/d/s/ as a popular audio brand.

a/d/s/ founder, Dr. Godehard Guenther, is a brilliant man who was always a little ahead of the market when it came to product ideas. in the late 70's through early '80's a/d/s/ speaker sales were doing startlingly well in both home and automotive categories, but Godehard felt that people would begin to appreciate the benefits of purchasing complete, high quality integrated system solutions. This was quite common in Godehard's native Germany, but in the US we had a mix and match mentality. This thinking resulted in a/d/s/ purchasing the Braun electronics division from then owner, Gillette. The plan was the Braun Atelier electronics were to become a/d/s/ Atelier. This turned out to be an extremely ambitious project because the plans were in place for the complete electronics line, but only a few of the new models were fully developed at the time. The additional personnel and costs to tool and develop the line were phenomenal. The development of many of the products, such as the flagship R4 receiver would be simple today but extremely difficult back then. In the late 80's the building-blocks didn't exist to make a computerized digital receiver with full system control and multi-room capability like we take for granted today. Now there are chips for virtually everything, but a/d/s/ needed to develop everything from scratch. While speaker sales were still going strong, and the automotive division was doing great under the leadership of industry leaders John Bishop and John Caldwell, the costs of this expansion into home electronics were taking their toll.

The M and CM series speakers designed by Dana Hathaway, were introduced at this time also. They represented a departure from the original a/d/s/ sound but were quite good and arguably were objectively "better" in all technical aspects. They continued to be extremely well reviewed, but since the lion's share of the marketing resources were directed towards Atelier the M-series didn't get the same focus as the earlier products, so they aren't as well known today. Just after this, a/d/s/ became involved with a start-up company that had a great concept called Frox. The Frox products were the forerunners of today's Media Center PC's, foreshadowing all of the media integration and home automation we now take for granted. The difficulty was that this system was envisioned when PC's had 286 processors and 512K of RAM, so this was also not a simple project. We have quad-core processors and multiple gigs of RAM to do that today. The plan was for a/d/s/ to provide the powered 5.1 speaker systems that connected digitally to the Frox controller through optical cable. The a/d/s/ speakers actually got built, but the Frox systems never got off the ground due to software and technical difficulties, resulting in disaster for the company. So a/d/s/ ended up stuck with a lot of unsellable inventory, and took a further financial hit. I'm skipping quite a bit, because there were some other plans and projects that didn't go as expected, such as the worlds first expandable 6-zone multi-room multi-source whole-house system controller with LCD control pads (in 1986!). All these things played a part watering down the company's ability to market their products effectively. Eventually, a/d/s/ sold Braun Electronics back to Gillette, and cleaned up after the other projects, but the damage was done. This all led to a need for a capital influx which led to a merger with Museatex from Canada, and the formation of ADS Technologies (ADST) as the holding company that had a/d/s/ and Museatex as their brands. In this era the company was run by Kurien Jacob, an audiophile and turnaround specialist who orchestrated the merger. Kurien integrated the Museatex and a/d/s/ operations. a/d/s/ benefitted by the addition of a superb audio engineer, Ed Meitner, to the group. a/d/s/ introduced some interesting and good performing products during this era, but with the exception of a few car speaker products none achieved the market traction of the earlier home speakers. Over the next few years, ADST acquired autosound manufacturers Orion, and Precision Power (PPI) along with ribbon speaker maker Apogee Acoustics. The a/d/s and Apogee factories were combined in Wilmington, MA, and later moved in with with Orion (and later PPI) into a new purpose-built facility in Tempe Arizona. I left soon after this to join Cambridge SoundWorks, so don't know much more about what went on inside the walls. I do know that at this time, the autosound side of the business was outperforming everything else, so the folks running the business apparently focused their efforts in that direction. The unfortunate fallout of this was that many of the excellent home products from a/d/s/, Apogee, and Museatex are no more. Ultimately, as has been mentioned elsewhere, ADST was purchased by Directed Electronics. At least to my eyes, it would appear that Directed doesn't seem to have much interest in continuing a/d/s/ as a high-technology value-added brand. It looks like a few of the holdover products may still exist, but the newer products carrying the brand logo appear to be generic turn-key products with nothing special to offer.

Godehard Guenther, on the other hand is still making some cool, innovative products under the Soundmatters brand. Although a different focus than the original a/d/s/, some of the Soundmatters products (especially the subwoofers) show some clearly different thinking that is definitely a Godehard Guenther trademark.

Bob

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Sorry this is so many months after the original post, but I just came across this today. Perhaps I can shed a little light on your whatever happened to a/d/s/ curiosity. I was employed by a/d/s on two occasions. The first from 1983 - 1993, then from 1996 - 1999, so was in a position to see some of the changes that resulted in the eventual downfall of a/d/s/ as a popular audio brand.

Bob

Bob, that was an excellent and lengthy addition to this post. It is great to have someone who was part of ADS to add to these comments. I do have a question for you: who actually did the design work at ADS on the L1590, L1290 and L1090 series (and other variants) that were introduced in the mid-1980s? These speakers, even to this day, are excellent designs and among the better products ever designed by ADS.

Also, I believe that the company used the ADS trademark until the M-series was introduced, and then a change was made to a/d/s/. I incorrectly listed the L1590 as an a/d/s/ version; it should have been ADS L1590.

--Tom Tyson

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... who actually did the design work at ADS on the L1590, L1290 and L1090 series (and other variants) that were introduced in the mid-1980s? These speakers, even to this day, are excellent designs and among the better products ever designed by ADS.

i could be completely off but i thought it was Mike Kelly ....

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i could be completely off but i thought it was Mike Kelly ....

Mike Kelly was the VP in charge of product design at the time, so he would be the ultimate decision maker, but I believe Dick Moore was also heavily involved. This was just before I joined, so I'm not sure exactly what the exact contributions of the various team members were, but Dick's initials were on most of the documentation. Dave Marshall (also now with Ariel) was the mechanical designer. The industrial design was from Braun Design in Germany. One interesting tidbit is that the cabinets were manufactured by a German furniture company named Hados, and sent here for installation of the ADS made drivers. This is a complete reversal of the typical loudspeaker company practice of building ones own cabinets and stuffing them with drivers built elsewhere.

Bob

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The L1590 was a 1980's speaker held in high regard for its uniform on-axis output as well as it's relatively flat acoustic-power output, the downfall of so many loudspeakers. The acoustic-power frequency response is basically the integrated power output of a transducer as measured throughout a listening environment, and is a measurement of the speaker's abillity to disperse sound over a wide vertical and horizontal axis. The end result was a speaker that was capable of great accuracy and realism, as well as a speaker with very "spacious" sound characteristics.

The L1590 also had very low distortion and excellent deep-bass capability with its two 10-inch acoustic-suspension woofers mounted in separate chambers within the heavily braced cabinet. The -3 dB point of this speaker was approximately 28 Hz, so the low-frequency extension was also excellent. Power-handling for the woofers was top notch with the 2-inch-diameter voice coils with 1.5-inch high windings, giving greater than .5-inch linear overhang.

Subjectively, earlier versions of the tweeter used A/D/S/ was considered to be bright sounding, but A/D/S/ made changes to the crossover and the magnet structures on this vintage of the speaker, and the L1090, L1290 and L1590 were a bit more reticent than earlier models.

--Tom Tyson

These ADS Tower Loudspeaker brochures may have been previously listed, and the files are large, but here they are again: (1) ADS L1090, (2) ADS L1290:

--Tom Tyson

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These ADS Tower Loudspeaker brochures may have been previously listed, and the files are large, but here they are again: (1) ADS L1090, (2) ADS L1290:

--Tom Tyson

The files were apparently too large and didn't pass the server. I'll try again later in a modified format.

--Tom Tyson

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The L1590 was a 1980's speaker held in high regard for its uniform on-axis output as well as it's relatively flat acoustic-power output, the downfall of so many loudspeakers. The acoustic-power frequency response is basically the integrated power output of a transducer as measured throughout a listening environment, and is a measurement of the speaker's abillity to disperse sound over a wide vertical and horizontal axis. The end result was a speaker that was capable of great accuracy and realism, as well as a speaker with very "spacious" sound characteristics.

The L1590 also had very low distortion and excellent deep-bass capability with its two 10-inch acoustic-suspension woofers mounted in separate chambers within the heavily braced cabinet. The -3 dB point of this speaker was approximately 28 Hz, so the low-frequency extension was also excellent. Power-handling for the woofers was top notch with the 2-inch-diameter voice coils with 1.5-inch high windings, giving greater than .5-inch linear overhang.

Subjectively, earlier versions of the tweeter used A/D/S/ was considered to be bright sounding, but A/D/S/ made changes to the crossover and the magnet structures on this vintage of the speaker, and the L1090, L1290 and L1590 were a bit more reticent than earlier models.

--Tom Tyson

Powering the ADS L1590s and L1290s:

I have found that any number of power amplifiers can do a decent job driving these speakers, but the ADS speaker efficiency is relatively low and their power-handling capability is high, so I have been using QSC professional amplifiers of late to drive them. For the L1590 I use a QSC PLX-3602 Two-Tier Class-H amp (switching power supply), and the sound is effortless. This amplifier is capable of nearly 1000 watts/channel into the 1590s, so fusing is a must. For the L1290 I have been using a slightly different QSC design, a class AB GX3 design, about 300 watts/channel. The 3602 is a highly advanced, high-power design with very low noise and low distortion, but frankly it is very difficult to discern any differences between any quality amplifiers operating in their safe range driving into an impedance that does not cause problems.

The reasons for using pro amps are simple: these amplifiers are far more rugged and conservatively designed than their consumer equivalents, and they are reasonably priced due to the competitive nature of the pro-sound market. These amplifiers can operate into very low impedances and capacitive-reactive loads without any stress, and the distortion levels are usually in the 0.05% range across the band. Also, the consumer-audio business is dying with the lack of interest in quality "stereo" high-fidelity sound (iPods and Bose Docking Stations rule now), but the professional-audio market is still very strong. In fact, the QSC RMX 2450 is the best-selling amplifier in the world, and it is among the most reliable devices of its sort available with a failure rate of less than 1/2 of 1%. Crown, Crest and other professional manufacturers offer similar devices.

The end result is effortless sound quality from these speakers, and the knowledge that very little can cause problems for these amps. There is fan noise, but the newer pro amps have a low fan noise unless the amps are driven excessively hard.

--Tom Tyson

Image: rack-mounted Crown and QSC amplifiers

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Powering the ADS L1590s and L1290s:

I have found that any number of power amplifiers can do a decent job driving these speakers, but the ADS speaker efficiency is relatively low and their power-handling capability is high, so I have been using QSC professional amplifiers of late to drive them. For the L1590 I use a QSC PLX-3602 Two-Tier Class-H amp (switching power supply), and the sound is effortless. This amplifier is capable of nearly 1000 watts/channel into the 1590s, so fusing is a must. For the L1290 I have been using a slightly different QSC design, a class AB GX3 design, about 300 watts/channel. The 3602 is a highly advanced, high-power design with very low noise and low distortion, but frankly it is very difficult to discern any differences between any quality amplifiers operating in their safe range driving into an impedance that does not cause problems.

The reasons for using pro amps are simple: these amplifiers are far more rugged and conservatively designed than their consumer equivalents, and they are reasonably priced due to the competitive nature of the pro-sound market. These amplifiers can operate into very low impedances and capacitive-reactive loads without any stress, and the distortion levels are usually in the 0.05% range across the band. Also, the consumer-audio business is dying with the lack of interest in quality "stereo" high-fidelity sound (iPods and Bose Docking Stations rule now), but the professional-audio market is still very strong. In fact, the QSC RMX 2450 is the best-selling amplifier in the world, and it is among the most reliable devices of its sort available with a failure rate of less than 1/2 of 1%. Crown, Crest and other professional manufacturers offer similar devices.

The end result is effortless sound quality from these speakers, and the knowledge that very little can cause problems for these amps. There is fan noise, but the newer pro amps have a low fan noise unless the amps are driven excessively hard.

--Tom Tyson

Image: rack-mounted Crown and QSC amplifiers

I have an Ads L1290 and the rare PA-1. anyone know where I can fix one?

an yes, the ADS speakers are inefficient. I was driving the pair with an old Rotel 1412 that actually could cut it for awhile, until overload conditions. But I'd love to get the bi-amplifiers working...

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I have an Ads L1290 and the rare PA-1. anyone know where I can fix one?

an yes, the ADS speakers are inefficient. I was driving the pair with an old Rotel 1412 that actually could cut it for awhile, until overload conditions. But I'd love to get the bi-amplifiers working...

I have a pair of 1590s that were floor models I bought in 1985 or so. Last night, I blew the tweeter fuses, but I'm not sure I have the right ones. What amp are they supposed to be? I thought it was something odd, I had in 1.5 amp fuses, which blew. Are they supposed to be 1.6 amp?

I had shopped a long time, finally settling on the 1590s. They sound great on all kinds of music, from acoustic/classical to hard rock. I am using a Proton D1200 to power them, it can hit 500 watts on the peaks. I just need to know what size fuse to put back in my speakers...

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I have a pair of 1590s that were floor models I bought in 1985 or so. Last night, I blew the tweeter fuses, but I'm not sure I have the right ones. What amp are they supposed to be? I thought it was something odd, I had in 1.5 amp fuses, which blew. Are they supposed to be 1.6 amp?

I had shopped a long time, finally settling on the 1590s. They sound great on all kinds of music, from acoustic/classical to hard rock. I am using a Proton D1200 to power them, it can hit 500 watts on the peaks. I just need to know what size fuse to put back in my speakers...

Which version L1590s? Are they the first version or the L1590-II? The fuse for the tweeter is a Bussman 3AG 1.6A for both versions, I believe, but the fuse for the midrange (which was a 3AG 2.5 Amp) was dropped in the Series II speaker as being unnecessary. What kind of music was being played when the fuses blew? The speakers are rated for 500-watt peaks, and in actuality easily handle upwards of 1000-watt peaks, but no speaker can readily handle sustained high-energy rock music or the like, with intense high-frequency energy being put into the tweeters. During the April 1984 Stereo Review Equipment Test Report on the L1290 (almost identical tweeter and midrange to the 1590), Julian Hirsch tested the tweeters with high-energy tone bursts of up to 2,500 watts into the tweeter at 10kHz without distortion, so the driver will handle a lot of power if it is short term and clean. Your Proton D1200 might be clipping on some of the high-energy peaks, as well.

--Tom Tyson

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Powering the ADS L1590s and L1290s:

...the ADS speaker efficiency is relatively low and their power-handling capability is high, so I have been using QSC professional amplifiers of late to drive them...

...an yes, the ADS speakers are inefficient...

My L1530s, the predecessor to the L1590 and very similar except for the cabinet design, are rated at 95dB 1 watt/1 meter, which I think is insanely efficient. I was used to 89 dB or so before I acquired these monsters. I power them with a Nak PA7II and have never seen the overload lights even flicker for an instant.

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I had a pair of 1290s for a number of years and never found them to be difficult to drive either. I had them on a variety of amps ranging from Adcom GFA-555 (run from an a/d/s/ R4), to a Yamaha DSP-A1. Of course their needs were more than the typical bookshelf speakers, but of course, you are talking 2 acoustic suspension woofer in separate chambers, so......

I must say that I remember them fondly!

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My L1530s, the predecessor to the L1590 and very similar except for the cabinet design, are rated at 95dB 1 watt/1 meter, which I think is insanely efficient. I was used to 89 dB or so before I acquired these monsters. I power them with a Nak PA7II and have never seen the overload lights even flicker for an instant.

audiomagnate,

Judging by a previous message, you may no longer be on this site, so we're sorry to see you leave if this is the case.

With regard to the L1530's efficiency (sensitivity), it was rated by ADS at 95 dB (in a 2000 cu. ft. room), about 5-dB more efficient than the later L1590, rated at 90 dB (in an "average-sized" room). ADS recommended a minimum of 10 watts and 300 watts maximum for the 1530, whereas the 1590 recommended 15 watts minimum and 500 watts maximum. However, the principal reason for this high efficiency rating was the 1530's use of the samarium-cobalt magnet in the 1-inch tweeter vs. the standard ceramic magnet used in the later speakers. For some reason, ADS had the spectral level set fairly high (read "bright") for the L1530 1-inch dome tweeter, but this was later changed in the 1590 ¾-inch tweeter. Also, the woofers in the 1530 had less voice-coil "overhang" in the woofers than with the later 1590 system; as a result, 1590 had lower bass distortion and greater power-handling ability than the earlier 1530 system. It is possible that the 95-dB rating for the 1530 was slightly optimistic, but the system was definitely more sensitive than the later 90-series speakers. The 1530 was also rated with a 25-20,000 Hz frequency response, ±3dB, meaning that the 1530's system resonance was very slightly lower than the 1590, rated at 28-27,000 Hz ±3 dB. In any event, both systems are impressive tower speakers of very high quality!

--Tom Tyson

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The L1590 was a 1980's speaker held in high regard for its uniform on-axis output as well as it's relatively flat acoustic-power output, the downfall of so many loudspeakers. The acoustic-power frequency response is basically the integrated power output of a transducer as measured throughout a listening environment, and is a measurement of the speaker's abillity to disperse sound over a wide vertical and horizontal axis. The end result was a speaker that was capable of great accuracy and realism, as well as a speaker with very "spacious" sound characteristics.

The L1590 also had very low distortion and excellent deep-bass capability with its two 10-inch acoustic-suspension woofers mounted in separate chambers within the heavily braced cabinet. The -3 dB point of this speaker was approximately 28 Hz, so the low-frequency extension was also excellent. Power-handling for the woofers was top notch with the 2-inch-diameter voice coils with 1.5-inch high windings, giving greater than .5-inch linear overhang.

--Tom Tyson

Update on the ADS L1590-2 woofers: the following images are details of the construction of the dual-10-inch woofers used in the L1590-2. The voice coil is coated with a special high-temperature coating, and the coil is wound on a special Kapton former for excellent power-handling capability. The coil is 2-inches in diameter. The cone is a special-density pulp mixture engineered by ADS to prevent breakup distortion, and with the very low crossover frequency, the woofer's output is very uniform down to -3dB point of 28 Hz, with natural rolloff below that frequency. There is usable response down to 20 Hz and below at fairly high output levels.

post-100160-0-88163500-1342281340_thumb.

Fig. 1: Inverted view of high-output 10-inch ADS Stifflite Woofer used in the L1590-2

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Fig. 2: Detail of the conformal high-temperature coating of the 2-inch diameter, long-throw ADS L1590-2 dual 10-inch Woofers

post-100160-0-97431000-1342281538_thumb.

Fig. 3: 2-inch Diameter Voice Coil used on the ADS L1590-2 dual 10-inch Woofers

post-100160-0-99342200-1342281583_thumb.

Fig. 4: Detail of the cross-section of the special felted cone assembly of the 10-inch ADS L1590-2 Woofers

--Tom Tyson

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Tom,

I agree--the ADS '90 series were excellent loudspeakers. I came very close to buying a pair of 1290's. I also thought the 1290's somewhat slimmer profile made it a more attractive speaker than the 1590, which was somewhat 'chunky.'

I seem to remember that these speakers had the unusual option of having a power amplifier attached to the rear of the cabinet in a recess that was made to accept an ADS sub amp. So equipped, these ADS speakers had powered 'subwoofers' and passive mids/highs, pre-dating the so-called Powered Towers of Definitive Technology by some 10 or 15 years.

I know I have some lit on these ADS speakers somewhere in my dusty archives, but perhaps you might shed some light on this innovative aspect of their design.

It always struck me as strange that these ADS speakers did not enjoy wider critical acclaim (were any of them reviewed by the Big Three?) or more widespread commercial success.

Steve F

I owned the 910 , which WAS "chunky". Mounted on their optional metal stands, it looked like R2D2 on steroids. On paper , they were pretty impressive. Living with them for many years, I thought their spectral balance to be between the AR3a and the AR10. Build quality was superb and just about indestructable. I purchased them partly because Deutch Grammaphone used them as monitors. My biggest gripe about them was their imaging capabilites compaired to other "studio monitors". I'm presuming the "towers" discussed here was better in this regard.

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I owned the 910 , which WAS "chunky". Mounted on their optional metal stands, it looked like R2D2 on steroids. On paper , they were pretty impressive. Living with them for many years, I thought their spectral balance to be between the AR3a and the AR10. Build quality was superb and just about indestructable. I purchased them partly because Deutch Grammaphone used them as monitors. My biggest gripe about them was their imaging capabilites compaired to other "studio monitors". I'm presuming the "towers" discussed here was better in this regard.

Gerry,

I never owned the ADS 910s, but I was very impressed with their sound on several occasions. At the local ADS dealer close by, I was able to compare the 910s—with levels equalized—with my own AR-3as, and the ADS was marginally more powerful in the deep bass, as expected with its lower system resonance. The 910 also had more "clarity," but it was also more forward-sounding to me; and what it had in "clarity" over the AR-3a, it seemed to give up in spaciousness. So that might have been a wash. Both speakers are such great reproducers, it's difficult to make a true value judgment on them; however, for sure, the ADS 910s could pound out higher SPL levels more effortlessly—perhaps without strain—than the AR-3a, but then the 910 was intended as a monitor speaker. The 910 never seemed muddy at any sound level I could withstand.

That big, broad front baffle board on the ADS 910 seemed to be in vogue briefly during that time (another example was the Andy Kotsatos Boston Acoustics A100 with the wide front face), but I would think there would be interference effects on a grand scale if the speaker were measured in the near field—again, not a big factor in the reverberant field. The later ADS tower speakers—especially the late-80s L Series 2 versions—were narrower and had significant improvements in dispersion and acoustic power over the 910 series. This acoustic power might be unimportant to some such a Speaker Dave, but it seemed to make the newer "L" speakers more three-dimensional. I really don't know if there were changes in the so-called "imaging" of the speakers, but overall the (especially the 1590) towers were considered better performers.

The ADS 910 had a 550 and 4000 Hz network (12 dB/octave, as with the tower speakers), whereas the 1590 had 350- and 5000-Hz crossover frequencies. In this way, the 1590 used the excellent 2-inch dome to handle a great deal of the important middle frequencies, and thus the dispersion at upper bass frequencies was improved. The 1590 also had a lower fc (33 Hz vs. 39 Hz) and much more robust 10-inch woofers than the 910. I also believe the 1590 was a significant improvement over most of the earlier ADS tower speakers, such as the 1230 and the 1530. For one thing, the treble was toned-down with the improved dome drivers in the newer series. The humongous ADS 2030 may have been the best—I don't know—but it was just gargantuan with its multiple mids and tweeters and dual 14-inch woofers, and it was a favorite of the Telarc recording group for a long period of time.

--Tom Tyson

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