[poseidonsvoice]

Yeah, you're right. We're audiophiles, not sound engineers. Learning to take measurements at the level you're talking about seems exhausting and antithetical to the goal which is to sit back and enjoy the music. 

Besides, most of us don't control our audio space -- we share it with wives, kids, friends, etc. So whenever someone, for example, tells me to get some room treatment, I just shake my head. I think the best approach and question for most of us is -- "Based on my situation (budget, room size, WAF, time, etc.), how can I achieve the best possible sound?"   

Fair enough. First and foremost I am not a sound engineer and my job is far away from anything to do with audio engineering or acoustics. What I did discover years ago, was that achieving good bass (i.e. the frequencies above 10Hz and below 300Hz) has more to do with measurements and acoustics than it does about setting things with the human ear. The ear is useful with the end result (as a final judge or arbiter if you will) but it has an inability of taking you to the end result in an expeditious manner (i.e. you can spend years/decades). Measurement software like REW in particular is now free or inexpensive and very powerful. It is also constantly upgraded which is a boon. A dedicated room isn't required but a yearn to improve one's 2 channel experience is (and honestly your room might be dedicated 'enough' given that you are able to fit 3 subs). That is the only thing that drove me. Of course I was initially driven after having experienced the end result in another audiophile's home (an audition always helps!). I used and still use the measurements as a tool towards an end goal. And to be honest, there are entire forums dedicated to helping audiophiles achieve this end goal, it's just not that popular here. I can only encourage you to make those measurements and post them on AV Nirvana where the designer of REW participates. You don't have to use REW though as there may be other measurement softwares that are easier to learn or use. I am not aware of them, nor did I explore them as I found REW rather easy to use.

Achieving an improved bass response only helped me enjoy my music more. Soundstaging blossomed, midbass detail was greatly enhanced, and midrange/treble detail was far more apparent as I was not concentrating on bass issues in the room. Dynamics were unshackled. Bass ceased to be an impasse to the music being expressed. It literally was a night and day difference.

Perhaps the method in which I did it was somehow overzealous to you (and to others) and an antithesis to being or becoming an 'audiophile.' Yes, during the time that I spent measuring I wasn't listening to or enjoying music. But I was learning. And that is powerful.

Best,
Anand.

[Early B.]

Fair enough. First and foremost I am not a sound engineer and my job is far away from anything to do with audio engineering or acoustics. What I did discover years ago, was that achieving good bass (i.e. the frequencies above 10Hz and below 300Hz) has more to do with measurements and acoustics than it does about setting things with the human ear. The ear is useful with the end result (as a final judge or arbiter if you will) but it has an inability of taking you to the end result in an expeditious manner (i.e. you can spend years/decades). Measurement software like REW in particular is now free or inexpensive and very powerful. It is also constantly upgraded which is a boon. A dedicated room isn't required but a yearn to improve one's 2 channel experience is (and honestly your room might be dedicated 'enough' given that you are able to fit 3 subs). That is the only thing that drove me. Of course I was initially driven after having experienced the end result in another audiophile's home (an audition always helps!). I used and still use the measurements as a tool towards an end goal. And to be honest, there are entire forums dedicated to helping audiophiles achieve this end goal, it's just not that popular here. I can only encourage you to make those measurements and post them on AV Nirvana where the designer of REW participates. You don't have to use REW though as there may be other measurement softwares that are easier to learn or use. I am not aware of them, nor did I explore them as I found REW rather easy to use.

Achieving an improved bass response only helped me enjoy my music more. Soundstaging blossomed, midbass detail was greatly enhanced and midrange/treble detail was far more apparent as I was not concentrating on bass issues in the room. Dynamics were unshackled. Bass ceased to be an impasse to the music being expressed. It literally was a night and day difference.

Perhaps the method in which I did it was somehow overzealous to you (and to others) and an antithesis to being or becoming an 'audiophile.' Yes, the time that I spent measuring, I wasn't listening to or enjoying music. But I was learning.

I admire your fortitude and don't doubt that what you did significantly improved the sound of your system from the top down. At the very least, I should try and figure out how to set the PEQ on my A370 amps. The Rythmik website ain't much help. I've always kept the PEQ in the "off" position. Today, I turned them on, set everything at 12 o'clock, popped in some Stanley Clarke, and could already see the benefit of tinkering with the PEQ if I knew what I was doing. I won't make any promises, but I'll look deeper into how to measure my room and go from there.

   

[poseidonsvoice]

Yippee! The acoustic gods are smiling 

Sometimes I feel that fellas give up because of “analysis paralysis.” I hear it all the time on phone calls with audiophile colleagues.

Best,
Anand.

[mlundy57]

I'm with Anand here. REW has been a big help in getting my subs dialed in. Both with using the PEQ to bring down humps and with Phase to get the subs properly aligned with the mains. REW shows me where the problems are and gives me feedback on exactly what a change I made did. It lets me see how a change compares with what I had before the change and lets me write notes about a change. This way I can keep track of what I'm doing. Once I've dialed everything in individually with REW, I sit back and listen. If something sounds off, I may tweak the physical position. Once I no longer hear what was off I recheck REW. Sometimes when I move something the phase will be off again so I readjust then listen again. Once I'm satisfied with what I'm seeing on the graphs and with what I'm hearing I'm done. For one listening position, this takes me about 4 hours, but I haven't added a rear sub to the mix yet. Once I have time, I'll incorporate the HT sub in the back of the room for music also.

[JLM]

The concept behind swarm is to limit bass production to the subs alone, big full range floor standing speakers need not apply as they act as subs in the very wrong room locations if set up away from walls for the best imaging performance.  (Side by side subs just double the in-room bass peaks/dips.)  Am a believer in room first, swarm second, treatment third, and room correction software last.  Sorry if that's not what you want to accept, knowing that achieving a better room shape/size can be terribly inconvenient.  Again, I'd apply REW/Dirac last as it only applies to a narrow listening area and so provides an artificial versus a physical/natural solution.  This follows Earl Geddes' teachings.  We all know of audiofools who way over spent on gear for the given space. 

Keep in mind with all this that it's all about the room shape/size 'fighting' against the physics of bass sound wave sizes and how those waves function in a residentially sized room which can easily cause 10 - 20 dB peaks/dips.  A tiny room is bound to be near cubic - a horrible sounding space.  A long skinny room is bound to sound like a tunnel.  A large but low room sounds claustrophobic.  The ear adapts quickly leading to sonic confusion but ideally the room shape should follow something like the Fibonacci ratios (3:5:8:13:21) to minimize induced peaks/dips, refer to Toole's "Sound Reproduction". 

The swarm concept is to even out the in-room bass peaks and dips by spreading out the 3 or 4 bass sources (ideally in a staggered manner).  Again refer to "Sound Reproduction".  I have my subs in a Fibonacci ratio of spacings from the corners.  The experts suggest locating one sub off the floor and trying one sub out of phase. 

Room treatment is another whole can of worms but know that the size of the sound waves (10-50ft) precludes the use of diffusion.  So absorption is the only alternative and most materials are poor absorbers of bass frequencies.  Owens Corning 703 fiberglass is the best material, that's why I have ten 2ft x 4ft GIK 244 panels in my room. 

I know you younger computer oriented guys want a software solution, but in most cases DSP is a bandaid when the patient needs surgery.  DSP should considered as the icing on the cake and only applied last.  If you're saddled with a crummy room, can't install subs, and can't add treatments suggest using headphones. 

[nickd]

JLM,
While the thread is about the benefits (and set up) of additional subs, DSP is more available now than ever. I lived without it for 35+ years with many tube and SS systems. Horns, OB, Line Source, monitors, floor standing etc. Some from the worlds best designers.

My room is 14’ 6” w X 23’ d X 9’h. Some room treatments and a pop out to get the gear out of the room. I have a 18” custom transmission line sub built in to the pop out because it is huge and would not fit in room.

After investing in quality DSP based room correction, I could never go back. I’m sure I would have kept my LS9’s if I would have known how much difference room correction can make.

My rig offers a “bypass” mode that brings you back to reality. With the last 10 pair of Loudspeakers in my room priced from $300. monitors to $30,000. Reference grade towers, the improvement is always surprising.

While I agree with you that DSP might not be my first advice “go to” for improvement, good room correction software in a quality processor is game changing.

[Early B.]

FOLLOW-UP...

I looked into learning how to conduct my own measurements, downloaded REW, watched a few youtube videos, visited some forums, etc., and quickly realized once again -- hell, no! Too much time and energy is required for me to learn it.

Instead, I invited a technically-astute, audiophile friend over my house to measure my low end room response using REW. Actually, it measured quite well, with the exception of a minor bump at 35Hz. We made a couple of attempts to remove the bump, but eventually, I was happy to leave the settings as is.     

I finally sat down with a extended listening session last night and really like what the third sub is contributing. At times, it's subtle, but during bass heavy passages, it thumps hard! Love it. The vast majority of music I listen to is jazz vocals, so bass isn't a prominent feature of this genre until an upright bass is played or the drummer jams out. It's during these moments when the third sub provides a 3rd dimension to the bass, almost like an echo. It's akin to the difference between a drummer in a small jazz club vs. a lively concert hall. Hard to describe, but natural sounding nonetheless.
   

[lokie]

Good discussion fellas. I'm working through a lot of the same issues.
My main rig is in my living room, so, lots of compromises as a result.
I have two IB infloor subs (2-15" in ea) located right in front of my speakers. I am contemplating two more behind the listening position. Although I have both crawl space above and below the room, there are limitations as to where I can put them due to duct work etc..

I will be using a Berhinger 2496 to do the xover and some processing. Still working on the high pass as I want to keep upper bandwidth (between 80 and 100Hz and up) analogue and pure as possible. I have  Dalquist DQ-LP1 that needs recapped (know anyone?) and will give this a try.

Anyone have success with a Passive Line Level XO? That may be the way to go as well.
 

[JLM]

Have heard an attic installed I.B. sub, crossed over very low (40 Hz as I recall), wasn't impressed.  But the theory is good.  Why do are you thinking of adding more I.B. subs?  Have you measured bass peaks/dips?  Again, best to stagger bass sources around the room to avoid peaks/dips, otherwise you could just add to the problems.  How acoustically inert is the "infinite" space on the back side of the woofer (a big issue with I.B. just like any bass source)?

Also had a Behringer 2496 (a DEQ2496).  Hideously difficult to learn (thanks YouTube), but effective if your particular unit is reliable (a known issue).  Bought a modded version to use as a DAC and DEQ later on.  If it works why look for another solution?  Tried an "indirect" solutions (one device to measure, another to make adjustments) that left me wondering just how accurate the whole approach was.  And had a DSPeaker Anti-Mode 2.0 Dual Core that measured/adjusted <250 Hz (the correct bass cutoff frequency IMO).  But its display was too tiny to be useful. 

Now have Dirac Live (<500 Hz) built into my NAD M10 but with my 3 subs is still confusing.  Depending on the music, get the best sound with sans Dirac/subs, subs sans Dirac, or with both in play.  This is an 8ft x 13ft x 21ft room, mid-field listening, ten GIK 244 panels, and three tall randomly filled bookcases on side walls.

[lokie]

 "Have heard an attic installed I.B. sub, crossed over very low (40 Hz as I recall), wasn't impressed."
Mine needs some integration work but  from what I'm hearing at this point, they have tremendous potential. Very efficient and very low distortion. With just a moderate amp, they have gobs of headroom.

"Why do are you thinking of adding more I.B. subs?"
To implement a swarm and/or "out of phase" strategy. Why IB instead of conventional? because of room and ease of build with of crawl space above and  below the room.  I suppose I could use "in room" subs but would need to hide them in a "behind the couch" scheme or a coffee table/sub build. Both much more difficult, more expensive and less efficient than IB.
Have you measured bass peaks/dips?
Yes… kind of.  I have a microphone but REW has been extremely challenging for me. I have a bit more work to do before I dive in and try to make some decent measurements. But from what I’ve done so far, I have huge dips at 220 Hz and 50 hz… from what I understand that’s typical for untreated domestic rooms. There is also a hump at 100Hz. The rest of the response looks good.
best to stagger bass sources around the room to avoid peaks/dips, otherwise you could just add to the problems.

That’s the plan with the “back” subs. In either an out of phase strategy or a swarm strategy. The front subs wont be moving.

How acoustically inert is the "infinite" space on the back side of the woofer (a big issue with I.B. just like any bass source)?

The sub floor is dirt and the ceiling is roof rafters. Both have more than sufficient cubic feet to adequately support IB.

Also had a Behringer 2496 (a DEQ2496).  Hideously difficult to learn (thanks YouTube), but effective if your particular unit is reliable (a known issue).  Bought a modded version to use as a DAC and DEQ later on.  If it works why look for another solution?

Yes. Learning curve was steep, but I got it working OK. Had to work through a problem getting it a strong enough signal. I don’t want to use the Berhinger as a high pass xover. Will need something else for that.
 
 

[Ryan0348]

I use a Xilica xp 3060 for my subs and super mini base. It’s a dsp active crossover 24/96 40 point floating processors phase peq multiple crossover settings adjustable every 1hz. I got to it used for 600$ but new they were around 1500$. Everyone on the Klipsch forum loves for horns cause there opamps are pretty quite and there xlr in out with super low output impeadance. I also have a Marchand xm46 passive line level crossover that uses caps inductors and resistors. You can buy different modules for your crossovers or you can use there online calculator and do it your self. I really like my Xilica and along with room eq wizard it’s super easy to setup subs.