Oh Room Correction, how Far You've not Gotten

I have been excited about digital signal processing (DSP) since the early 90’s. I remember, naively, only thinking about frequency response, then thinking about how it might be useful in overcoming stored energy problems in drivers, and even compensate for compression, anything that could be mathematically modeled. Along with this was the servo controlled speakers from Velodyne and Genesis. Oh what great ways we’d have to overcome the limitations of driver design and even physics itself!! The infinitely powerful, all knowing computer of Star Trek applied to audio would surely solve everything and make it possible for every average music and film lover to have mastering studio quality sound.

After having great success with manually configured miniDSP units in my modest apartment in San Francisco and movies I wondered to myself how much better would a "real" room correction algorithm be than what I could tweak by hand. I read a paper by Floyd Toole where he scoffs at the idea of "room correction" altogether. Surely Mr. Toole, this paper is now old and has been superseded by modern research! Surely room correction is now worth it’s label!

After living with and playing with the Anthem room correction built into the MRX 520 I can tell you that for at least this example, Mr. Toole remains undefeated. Don’t get me wrong, it’s a decent HT receiver, far far better than one’s I’ve bought and discarded before. Also, the subwoofer integration and web interface are pretty sweet. What it does not really do well at all is create an immersive or enormous sound field which I was able to get before using miniDSP and OmniMic.  I have big booms but not the credibility and transparency I was able to create by hand tuning the EQ.

Over the rest of this year I’ll spend more time and money investigating exactly what ARC does, and whether or not I can do much better by hand tuning.

A really frustrating part of my purchase is that this amp does not give me any sort of ability to set and modify individual filters. I have some overall level controls but nothing like the sort of control more advanced DSP software gives you.

P.S. - Many of you will automatically and correctly point out that room treatment solves many problems that DSP/EQ cannot. Yes, that’s true, but this is a well treated room already. I’m specifically looking into what the ARC has done or failed to do in the frequency domain.



It's good to hear from someone who, at least, is open minded about DSP/Room Correction. First, by definition, DSP exists everywhere there is a digital signal. Furthermore, the term "room correction" is a bit misleading. These systems do not correct the room. These systems alter the signal (in the digital domain before amplification) so the output from the speakers and the contribution of the room work together for better time domain and amplitude domain results.

Automatic DSP/Room Correction systems are powerful tools but they are not all created equal. The top-line units are considerably more advanced than mid-line units. I would not use my experience with a mid-line system to suggest the capabilities of the current SOTA technology.

One can easily argue that some of the large, immersive sound field is a result of the room/speaker interaction. Our experience with advanced DSP/Room Correction shows us that if the recording has spacial information (large, immersive sound field, depth, height) then a properly corrected system reproduces it. It does not embellish recordings that do not has spacial ques. Systems without RC can be setup to embellish spacial effects. I am not suggesting either is right or wrong. What you enjoy the most is what is right for you.

Read what a few reviewers said about our full DSP/RC system at Capital Audiofest 2021. The system was all tube electronics (except for the DSP unit) and vinyl source only (no digital files).


It’s good to hear from someone who, at least, is open minded about DSP/Room Correction.

Hi Mike! @arion

I use it all the time. My main system uses Roon EQ and my HT relies on it for well, everything.

To be clear, I am not bemoaning DSP or digital equalization. Rather I had hoped that, specifically for home theater, the automatic speaker setup and EQ had become much more refined in creating a seamless 5 speaker sound field. Previously when hand-tuning my 5.1 system I achieved Atmos level immersion by hand calibration and the use of a pair of mini DSP units. Listening to Master and Commander would make you seasick and Hateful 8 had you dodging bullets.

I’m definitely not there with the Anthem Genesis tools yet. I fear this will take me some level of experimentation with outboard amps and re-introducing miniDSP to the mix.


I understand what you are saying. AutoRC doesn't do all and doesn't take into account a few things like personal preferences and an individual's hearing. We always tweak the system's auto-optimization. There are many manual settings to play with and it did take a while to understand what's best for our drivers.

One area were the system does a stunning job is with time domain issues. There is a clarity, naturalness and relaxed quality when the arrival time at the listening position throughout the entire range is spot on. The front end is not in the optimization and can heavily influence the outcome.


One area were the system does a stunning job is with time domain issues.


I've noticed this too.  I use a test DVD from Dayton to set the delay precisely across my speakers and it's a big difference. I have to say though, with the low frequency extension of your towers you hardly have the same crossover or phase problems most multi-way speaker makers have.  You have it easy. 😁


Yes, the low crossover point makes it easier. Building AMT drivers with a range from 120Hz to 24KHz, not so easy. Our raw towers have some interesting characteristics. There are different parameters designing a speaker system knowing it will be DSP/Room Correction controlled.



You use Trinnov with your speakers? Why not build a system with the DSP and amplification in one box? $ 35k for a system without the amps? Genelec, Kii and some others you get the whole package for that or less. 

@arion  Very true.  I wish I could buy one off the shelf, it would make my current center channel project a lot easier.

Yes, Trinnov is part of our speaker system.

Our Apollo 9 system comes with two 9 driver AMT towers, 2 woofers modules (each containing two 10" long throw woofers), 2KW amp for the woofers and the DSP unit. 22 high quality drivers in total. Our AMT drivers are very expensive to build. Check out the prices of Mundorf AMT drivers. Obviously the Apollos are more than just a pair of speakers.

We specifically designed the Apollo system so that owners can use their existing amps, or choose amps of their liking, to drive the towers. Some people use low power tube amps, others use SS amps. The towers are high sensitivity and can handle quite a bit of power so any good amp will work. I have been told by other industry professionals to not make our system so flexible and offer so many features. I respectfully disagree and believe that a true high performance audio system should provide options to the owner.

Our systems are designed to be modular so many options are available. We can (and sometimes do) supply all the amplification and have multi-channel processors for DSP controlled distributed bass. We can supply a complete system which only needs a turntable or music server.

As you can see, our system is very different than the ones mentioned. We have being active systems and DSP controlled in common and that's about it.


So I would need 18 channels of amplification not counting the bass to run a pair of these speakers ?

Our Apollo 9 system comes with two 9 driver AMT towers, 2 woofers modules (each containing two 10" long throw woofer

Do you have anechoic measurements or better yet Klippel NFS on any of your speakers?

"So I would need 18 channels of amplification not counting the bass to run a pair of these speakers ?"


The Apollo system processor has four channels total, two channels per side. Each tower is on its own channel and each woofer module (or multiples) is on its own channel. Woofer amps are supplied (unless user wants to use something else) so user typically supplies tower amp(s). Can be one stereo amp or a pair of monoblocks.

We have lots of data and measurements on our systems.