ATC SCM40A speakers

@tomcarr I'll chime in, as a newcomer to home audio with ATC, I am running the passive SCM40 V2's with a Moon North 761 amp. I spent a few hours at my local dealer listening to the SCM40 actives and passives. The Active versions were driven by the latest ATC preamp/controller. The digital source was the new Moon 681 network streamer DAC (also has a volume control so it can be used to drive amps direct). Spent a decent amount of time getting acquainted with the setup and performance and was really impressed song after song. Midrange coherence was the first thing to stand out to me; so expressive and natural. Big wide and deep sound field that just sounded so right. We switched to the passive version, placing them in the same spots (man those actives are HEAVY!! Like you can't believe how heavy they are in pretty small footprint) which were driven by Moon north 641 integrated amp (same Moon dac as source). Repeated the same tracks and then some more. Song after song I was really enjoying myself and that internal audio voice "buy these now" was whispering to me. At home I have the next level up in the moon north line, the 741 and 791. There was a definite synergy present with the simaudio gear and the ATC passives, we all heard it, and were all pretty blown away. I think I do agree about the sweet treble and warmish tone. I think however, to me, it's actually real sounding, not a coloration. I'm guessing it's the result of the seamless integration of the truly one-of-a kind ATC soft dome midrange and the woofer in the sealed cabinet design. The midband energy launches out and you can hear the tone of strings, bass lines, etc. The energy just passes through in a really compelling way. For me, this is new information. I've had tons of speakers passing through my quarters over the years, and there is definitely something to these ATCs that often just grabs me and carries me away in the musical energy.  Some of my favorite speakers to pass through here are Harbeths. I think the ATC's embrace what Harbeth gets so right in the midrange and builds on that at both ends of the spectrum.  I think you will be very impressed with the active versions - I might have just walked away with those but I am still enamored with power amps, and I really like what the 761 brings to the table and there is no way I can part with this amp yet.  It's good to read accounts of ATC active users running them with various line stages and tuning them to one's personally subjective appreciation. Good luck and let us know what you decide!

@dpac996 Thank you for the wonderful response!

I can understand why you got the passive versions. If I had that amp I would do the same thing!

Just need to sell the 803s...

I have to add to @dpac996 that it isn't just the integration of the ATC drivers, it's that they are all designed to achieve low distortion reproduction-this is NOT what most transducer designers aim for.  Low Distortion Driver Units sound simple and obvious but it's truly a rubik's cube of objectives.  For example, many performance attributes depend on other attributes and you cannot have all of them- you must choose.  For example, there is a clear link between efficiency and LF performance in a driver: want more efficiency? Expect less bass- and vice versa.  Low distortion requires very large motors (magnet structures) to exert more control over driver motion.  These larger motor structures are very expensive to make and so not big sellers to speaker manufacturers who buy a lot of drivers.   Because they don't sell well OEM, they are almost impossible to find and when you do they are 2 or 3 times the price of much more common cheaper drivers.  Almost no one makes their own drivers anymore; years ago everyone made their own.  ATC still makes all their own drivers in house in their own UK factory and doesn't sell any drivers OEM anymore (even though they began as an OEM manufacturer).   This is their primary  advantage. 

A good example is the KEF story, who was one of the first to actively research and design/build their own drivers.  One well know product they designed and built drivers for was the famed LS3/5a, the "BBC Monitor", supplied as a driver/crossover kit to various different [British] manufacturers who were licensed by BBC to produce this speaker for the BBC.  So all of the early LS3/5a designs had KEF drivers and crossover inside, with no reference to KEF on the outside.  Harbeth, Chartwell, Spendor and many more all used KEF drivers for their BBC speakers.  BBC would license two manufacturers per year for these, which is why there were so many different brands of"BBC monitors".  Some have even claimed some unique ownership of this design when it was really all KEF.   

Most speaker makers today don't build their own drivers, they buy them,.  Drivers require expensive employees and equipment to build and most manufacturers don't have enough sales to support a driver factory. So finding a low distortion driver on the OEM market like ATC is impossible-there too much price pressure to make enough money building/selling them to support it and ATC used multiple design innovations that are extremely difficult to copy. ( a dual suspension mid dome for example that is designed to work between 380Hz and 3500Hz).  

High power drivers are unique too and yes, they are readily available OEM  because the live sound speaker market is extensive and much larger than hi fi in sales.  The most popular drivers in hi fi are low cost ones that don't break but are usually not at the bleeding edge of performance.  Companies like Peerless, SEAS and Focal (and MANY others around the world) sell hundreds of thousands of drivers to all kinds of different speaker builders.  More often than not the same drivers are sold to multiple manufacturers.       

So the point to all this is the real secret to ATC is they "build their own" low distortion drivers which are properly integrated and account for a big portion of why they sound "different".   A very common reaction to ATC is "wow, I hear stuff Ive never heard before" which is a direct response to hearing low distortion for the first time.  This is what makes ATC popular in studio use, where it's a huge advantage to hear things others miss.

Brad

@lonemountain yep that's what I meant :) Thanks for the details. The more I learn about the engineering behind ATC, the greater is my appreciation for them. Cheers

@lonemountain Wow! Thank you for the information! Now I'm really worked up!