ATC SCM40

@jallan That’s pretty accurate overview ! I remember that GAS amp (I hate to say I’m that old) as at the time, they were excellent for the money. Ampzilla/son of was a great amp, more reliable than many others at the time. SAE was similarly reliable, but the GAS sounded better. Those were still the days of Phase Linear ($1 per watt) 400 amps!

People use that phrase "power hungry" and I get it, that phrase is often "situational" because I think this opinion comes from trying a low output amp (50W-75W?) that is often not as well designed as the higher power stand alone amps. Many of these demo experiments are with integrated amps or stand alone receiver company amps -not a high end design. The larger amps are usually ruled out due to cost, so usually not in play in a target system where people are searching for a bargain. Good example is a Crown D150- did not sound as good as the DC300. So sometimes it was companies just tried to make a cheaper amp that was lower power to fit the market, not just downscale the better higher power amp. (for background, it costs nearly the same to build a 75W or 150W amp vs a 300W one- the big costs are power supply, metal, meters, etc).

40s are optimized for low end extension vs efficiency, this is ATC’s preferred way of approaching loudspeaker design. Amps are cheap in this era so it’s not so difficult to get a larger 200W amp vs a 50W one. Much better place to invest $ is in the speaker with better low end and find a way to get a larger amp- even if not immediately. The big payoff is better low end AND much improved dynamics, which people don’t often think about until they are in their living room listening to "Fanfare for the Common Man" or Dark Side, or something that has some dynamics to it.  Dynamics plays such a significant role in realism.

Brad

Cannot go wrong here.  Ran the ATC 40 actives for some years with great results. They are world class speakers in either version and without being able to A/B them (passive vs active), I'm sure the actives would be more dynamic and immediate with attack.  That being said, my wife runs ATC 20 passives set on Sound Anchor stands with a monster Luxman 509X integrated and they are also scary good.

If you do go with the passives, heed the advice given regarding really good amplification and upstream source/cabling as these transducers will glaringly reveal all that you've done correctly AND incorrectly.

I always thought the appeal of ATC, besides the midrange driver that had its day, but would now probably among a group of quality mids, was that they were active and could be relied on to sound consistent compared to passive brands?  

@steve59  With all due respect,  I work with ATC so I am terribly biased in their favor, but I have worked in the speaker industry for 40 years with many different manufacturers including those with large engineering departments (such as JBL).  I have seen a lot and I know the OEM market a bit and how manufacturers make money there.  The ATC mid driver is not comparable to anything that I have seen on the market over the past 40 years and even today, it still stands alone.  The mechanical design and execution are beyond anything possible in OEM as it would be impossible to turn a profit on it.  No one would pay $1400 for one and put it in a speaker.  It has features that are not easily explained to a speaker owner as they are a physics and material science master class.  A far larger motor, a much greater stability in linearity due to two [dome] suspensions, lower distortion especially under higher dynamic ranges (115dB potential in the SCM150 to reproduce enormous peaks).  It is completely hand made to get the results the company owner wanted.  

You cannot build that driver on a machine and the techniques to build it are so nuanced that there is no copy available from anyone.  I would cost a bloody fortune to reverse engineer and you couldn't sell enough of them to make it worth it.  That's why there is no equal out there.  I agree there are a few 3 inch mid domes that look like the ATC from the outside.  But remove the driver and look at them vs the ATC side by side and there is no comparison between them-from a design and construction point of view.    And DSP cannot fix distortion inside the driver- once it's there, it's always there covering up details.  .

Brad

@lonemountain I agree, the ATC dome mid is overall the most impressive midrange driver I’ve ever heard.  Question for you — I’ve read the mid they use in the 40 is different from the one used in the 50 on up.  Can you explain the design and performance differences?  My understanding is a major difference is in power handling capability but wondering if there are some sonic differences too.  Just curious.