ATC buying advice

@lonemountain 

I'm afraid you are totally incorrect. Room correction is not an excuse to avoid room treatments. The best way to control the room is to use speakers that have controlled directionality. 

I have never measured a perfect loudspeaker. Most are fraught with amplitude deviations and worse, no two speakers are exactly the same. Even if they were exactly the same, put them in two different locations and they will be different. Digital EQ can correct this perfectly. I find that I still have to look at measurements and make adjustments manually to get both channels perfectly equal even after the computer has it's say. 

Room correction is a misnomer. It should be called speaker correction. It corrects two types of errors, amplitude and time (group delays). It is a panacea for subwoofer integration. The computer ignores the effects of late reflections and only corrects the amplitude errors caused by early reflections.  

None of this can be done in the analog world effectively at all or without causing other distortion. In the digital realm it is just juggling numbers, nothing else matters.

Let's assume for a second that you can design the perfect loudspeaker. Next try to build it and you will discover that all drivers and components deviate to some degree from perfect performance. All are designed to function within limits. The more tightly controlled devices are of course more expensive. 1% resistors are more expensive than 5% resistors of the same type. All these errors compound and create a degree of variability which can not be avoided even if you buy the finest components. 

I'm sure analog will persist as a niche market. People still collect Model Ts and old EV Patricians, one of the worst loudspeakers I have ever heard. But, like the cell phone, analog signal processing is doomed in the audio world. It is woefully inadequate. Granted, it is more of a challenge to put together a SOTA analog system. I can make a better performing system with less expensive components in a fraction of the time required to do it in analog fashion and that is really the key. Audiophiles on a budget (most of us) will be able to take huge leaps in performance at a very reasonable cost. Every audiophile I have done an in home demonstration for has immediately purchased a processor. It is fun to watch their eyes go wide when I kick it in.  

@soix 

There may be advantages over regular methods in some designs but they pale in comparison to what can be done digitally. You have to remember the designer has no idea what environment the speaker is going to be placed in and the room is 50% of the equation, some would say more. Analog can not deal with this. Eventually systems could be digital all the way to the speaker enclosure. With good cable you can easily run a 300 foot AES-EBU line without any loss. 

@jon_5912 

You have to be kidding me. Analog electrical engineering has been around for eons. I built my first amp when I was 13 years old. Digital signal processing is about 25 years old. It is an entirely different branch of electrical engineering and requires specific training. Programming the crossovers is easy, but that is not designing the circuitry. 

The only reason to do anything in analog is to hand an analog signal to the amplifier so you can listen with your analog ears. Unless you have a large record collection everything should remain digital up to the amps. Not only will such a system easily outperform any analog set up but you can also tune such a system to sound any way you want without any added artifacts. I digitize my phono stage and do the final RIAA correction by computer.  I also use tube amplifiers to drive ESLs.

@lonemountain 

Hi Brad,

DEQX does both speaker and room correction, separately. I greatly prefer the DEQX system which is more like the TacT system I am use to. I do not yet know how much manual tweaking I will have to do. As far as room correction is concerned, there remain issues that have to be handled acoustically. The room has to be in tolerance or you will just clip filters. The types of loudspeaker being used are also important. Certain speaker designs have far less room interaction. When it comes down to brass tacks there are two major types of errors, errors in amplitude and errors in time. These are easy to correct for, to a point. You cannot correct for echoes. There are problems that have no analog solution. Other then by shifting position there is no analog way to put a delay on a speaker, and the dimensions of the room and other practicalities put severe limitations on how far you can move anything. 

Yes, you can do an analog active loudspeaker. The only good reason to do that is you do not have the engineering to do it digitally. Digital signal processing including crossovers is, in every way, superior to analog signal processing. Analog signal processing is about as useful as tits on a bull.  The only exception is in the mind of the audiophile. Audiophiles are as change resistant as cyclists. It took a decade for the cycling community to accept synchro shifting. 

As for the type of amplifier that again depends on the loudspeaker, even the independent drivers can dictate amplifier choice. 

I hear a lot of support for "active" speakers. For speakers to be active the signal has to be digitized. This can lead to a lot of back and forth conversions. I am a firm believer in digital signal processing, it is a necessity if you want to get to a SOTA system now and in the future. Like a symphony orchestra it is best to have one conductor and traditionally this role has been taken by the preamplifier. There are now several preamplifiers with full DSP capability including room control, bass management, crossovers and EQ. The DEQX is the best of them all. The DEQX Pre 4 and Pre 8 utilize a 64 bit floating point system with the most current processor and are constructed in SOTA fashion. The Pre 8 even has a 4 way crossover! You can make any current loudspeaker "active"!  It even has a phono preamp. You have almost total control over the way a system sounds withing the context of the speaker design chosen. You can not turn a point source speaker into a line source one.