New Member, Where to Begin?

[Bowedtoothdoc]

This is my first post so please forgive a newbie if this has been answered or addressed already.

I have a multi use Home Theater/Music room so compromises have been made to accommodate both functions.

I came across a speaker review from a forum member that discussed DSP and further research led me to Mitch Barnett's book Accurate Sound Reproduction Using DSP.

In this post I am mainly interested in addressing my two channel setup which also utilizes four sealed subwoofers. The mains are  Danny Ritchie (GR Research) designed two way line arrays that I built from his plans called the Alpha LS and the Subwoofers utilize four 12in Shiva drivers each in their own sealed enclosure. I am familiar with Room EQ Wizard and have used it to equalize the subwoofers using a Behringer Feedback Destroyer Pro and the Behringer ECM800 microphone. I also have a Behringer DEQ2496 tied into my two main speakers and briefly played around using the built in room correction feature to equalize my mains. I must say that I was impressed with the results, but I'm not sure how accurate they are and for the time being I am not using any corrections from the DEQ2496. Most of my music is played off of my Home Theater PC using JRiver Media Jukebox, Optical Output to Denon Receiver, to Behringer DEQ2496, Balanced Output to Rotel RB1090, then heavy gauge wire to the mains which have the stock crossovers designed by Danny.

Mitch's book got me thinking about DSP and Acourate. I must confess that I have not read the entire book or purchased Acourate yet, but I am interested in what forum members think could be accomplished with my particular speakers? Line Arrays have their own set of advantages and disadvantages due to the sheer number of speakers used. My Alpha's have eight BG Neo 8 ribbon drivers and nine custom designed 6in CSS drivers in each speaker. Here is a link if anyone wants more info: http://gr-research.com/alphals.aspx

Coming from a large pair of Magnepans I have been very impressed with the Alpha's as they share some of the high end ribbon sound with pinpoint imaging, but also offer significantly more bass and dynamics along with being extremely easy to drive. So my question is how beneficial would DSP be for my situation and are there any other obvious weaknesses in my signal chain that should be addressed? I apologise for being long winded, but want to provide as much info on my setup to prevent confusion. Also I forgot to mention that the room has extensive sound treatment.

Any Input is greatly appreciated!!

 

[Fitzcaraldo215]

Classic, widely held acoustic theory, which is pretty uninpeachable really, is that below  the Schroeder frequency, the room determines bass response, not the speakers, assuming adequate speaker design.  Also, typical rooms can induce huge, narrow band swings in response due to room modes induced by dimensions, materials, etc.

 

The Schroeder frequency depends on the room, and there are various guesstimestimates of what typically it is, but a good,  high side rule of thumb might be to use 500 Hz, which way more than covers it.  Attempting to do the same taming of room modes with passive or active acoustic treatments is fraught with difficulties below Schroeder.

 

So, the biggest payoff of Room EQ is in the bass, although EQ might also have lesser benefits at higher frequencies.  So, fundamentally, you need to have adequate measurement tools, and adequate tools to apply those measured departures from measured frequency linearity on playback.  

 

Acourate is quite competent and will help do that by calculating filters that offset room/speaker issues.  They can be manually plugged into numerous playback scenarios.  

 

I may be lazy, though, so I just use Dirac Live  to measure and apply filters when plugged into my JRiver library playback.  It greatly simplifies the process, but it has fewer controls and options.  I do use it full frequency range, above and below Schroeder,  but with great satisfaction. 

[Bob Stern]

You could try the free (donation-ware) Room EQ Wizard software to calculate room correction filter values that you can input into the DEQ.

[Bowedtoothdoc]

   Thanks to you both for the responses! My DEQ2496 just went on the blink, which apparently is a common problem associated with the power supply due to a design flaw. Once I get it repaired or replaced I plan to go back and try built in room calibration feature and possibly use REW to make some adjustments as well. My room was built using a room calculator designed to optimize bass frequencies, but obviously that's only one part of the equation? Can anyone tell me the approximate costs of Acourate compared to Dirac Live?

[firedog]

Personally I've used DRC and also room treatments.
 

Corner bass traps - especially behind the speakers on the front wall - make a huge improvement. I'd recommend that as a simple and cheap way to vastly improve any room. No hassle, no measurements, no learning software. 
 

DRC can be great, but a little physical improvement of the room goes a long way. 

 

As far as the OP, especially as long as your DEQ2496 is on the blink, sure try some of the free DRC. It should further refine the sound, even in a treated room.  Most would agree it makes its most convincing use at frequencies below a few hundred hz, as mentioned. It is a bit of a hassle though to measure, set up and get your DRC profile worked out to how you like it  best. 

[Bowedtoothdoc]

Thanks Firedog!

I already have bass traps on the front wall and treatments on the rear wall where space allows.

Does anyone have any recommendations as far as free DRC to try?

[mitchco]

@Bowedtoothdoc Thanks for purchasing my book.

 

This one is free and works quite well: http://drc-fir.sourceforge.net/  There is a good guide on diyAudio: http://www.diyaudio.com/forums/full-range/275730-convolution-based-alternative-electrical-loudspeaker-correction-networks.html  There is also a huge thread on using this with line arrays: http://www.diyaudio.com/forums/full-range/242171-towers-25-driver-range-line-array.html  

 

Since you are using JRiver, you may find this useful and free as well: https://yabb.jriver.com/interact/index.php/topic,87538.0.html

 

Same with multi-sub optimiser: https://www.andyc.diy-audio-engineering.org/mso/html/

 

Be prepared to spend time with the learning curve, while not huge, will take a bit of time whichever approach you take.

 

A good commercial solution that will also automatically time align your subs to mains is:

https://www.computeraudiophile.com/ca/ca-academy/ integrating-subwoofers-with-stereo-mains-using-audiolense-r712/

 

No matter which route you choose, there will be an audible and measurable benefit. Line arrays are not a problem as you can see in the diyAudio threads. Personally, I would recommend a commercial solution like Audiolense which offers automatic time alignment of your subs to mains (if you have enough DAC channels) , reduces low frequency group delay, cancels standing waves, and has the easiest workflow.

 

Have fun and good luck on your journey!

 

Mitch

[Bowedtoothdoc]

Mitch Wow!

Thanks for taking the time to reply and for all of the useful links.

That's quite a bit of material to look over, plus I still have to finish going through your book.

I built my speakers back in 2003 and at that time there weren't many line array designs around, but it seems that the DIY Community has continued to push the envelope of design and innovation. I am looking forward to trying out some of your recommendations and will report back on either this thread or a new thread with my results and impressions.