Subwoofer equalizer recommendation

[jrhymeammo]

Could anybody here recommend me an equalizer for my powered sub? I do not wish to spend more than $200. I cannot find one with in/out speaker terminals. Thank you.

JRA

[N. Abstentia]

You've got a nice list of equipment there....why would you want to add a 'ghetto' piece like an EQ....to a subwoofer no less?

[kexodusc]

You've got a nice list of equipment there....why would you want to add a 'ghetto' piece like an EQ....to a subwoofer no less?

The real question you should be asking is why you DON'T have a parametric EQ for your sub in your system yet.
The subwoofer can be as expensive, and top quality as money can buy. It won't change the fact that a rooms acoustics will affect the frequency response by as much as +/- 20 dB (NOT an exaggeration). Every room will have modes and nodes that affect the response below 200 Hz or so. You wouldn't own a speaker that had a frequency response +/- 6 dB, why accept far worse than that for a subwoofer?

By not addressing the in room acoustics with a parametric equalizer, your bass response is the weak link in your system. The most popular Parametric EQ here is the Behringer Feedback Destroyer (BFD), for about $100. At that price, you can't afford NOT to have one. You're either setting the sub volume too high, or too low depending whether you adjust to a peak or dip in the response at the reference frequencie. Or you're somewhere in the middle and your room gives you crappy response.

The EQ isn't destructive to the audio frequencies when used properly, and even if abused, it's doubtful you'd be able to hear any distortion at frequencies below 80Hz - a lot of high-end subs got away with 10% THD for years.

Here's a chart of my early trials with equalization. I use to own the PW-2200 before I upgraded to my current 15" sealed unit. My room is a bit odd shaped, and I dont' have many placement option for a 15" sub...I've seen worse response charts than mine, however. The blue is before Parametric Equalization, the pink after:

Room treatments only help so much. My 2" foam (auralex, sonotec) made almost no difference at all below 200 Hz, where foam really becomes useless. The rigid fiberglass bass traps I made work about 5 times better than the foam below 200 Hz, and even that only knocked a few dB's off the peaks and valleys. It'd have to use a ton of bass traps to kill this mess.

So I EQ the rest. It is easily the best $100 I've spent on my system.

(edit: a note on the graph - I've since learned my Galaxay Audio SPL meter underscores the FR below 32 Hz or so...it's down about -5 dB by 18 Hz, so that bottom end is tilted up higher...still, it's a lot more accurate than my Radio Shack meter).

[Sir Terrence the Terrible]

You've got a nice list of equipment there....why would you want to add a 'ghetto' piece like an EQ....to a subwoofer no less?

I cannot believe that you wrote this! Ghetto peice?? LOL It is ghetto thinking that you can do without a sub EQ when using a sub in any room. I have never understood how people could just admire someone equipment, and not pay one bit of attention to the room that it sits in.

Harumph!:rolleyes5:

Hey, Kex type dude, how and where did you get the graph? I would like to do one of those for my rooms

[kexodusc]

http://www.hometheatershack.com/bfdguide/#004

I'm not on my home PC or I'd just send you the file, but you can download it fromt this excellent BFD guide webpage...(you now need to register to a forum, but oh well).

[Sir Terrence the Terrible]

http://www.hometheatershack.com/bfdguide/#004

I'm not on my home PC or I'd just send you the file, but you can download it fromt this excellent BFD guide webpage...(you now need to register to a forum, but oh well).

Thank you much National Minister of Pertanent Information.

[nightflier]

Kexo,

Thanks for the link. I had it saved somewhere before (probably the last time someone posted on this topic), but lost it. This time I printed it out, a whoping 28 pages, but worth it.

[jrhymeammo]

You've got a nice list of equipment there....why would you want to add a 'ghetto' piece like an EQ....to a subwoofer no less?

My sub/room creates this huge leap around 55-65, almost a gain of 12dbs compared to other avg frequnecy frequency. It is pretty annoying. EQ may alter sound quality but it's just lower frequency. If I had over $1200 to upfgrade my gear, I dont wish to spend it on a musical sub.

[jrhymeammo]

Hey kexodusc, what is the lowest frequency that I can set to adjust FROM, not to.

[kexodusc]

With parametric EQ's you can dial into any frequency - I know 20Hz is possible on the BFD, I'm sure you could widen the band to go lower or maybe even dial in lower.

The BFD is usually recommended for cutting frequencies (like most parametric EQ's for bass), but boosting "can" be done if you're very careful. If your seated in a spot where the room is naturally causing cancellations, all the boosting will do is eat up amp power.

[E-Stat]

Could anybody here recommend me an equalizer for my powered sub? I do not wish to spend more than $200. I cannot find one with in/out speaker terminals. Thank you.
Hmmm. Sub doesn't have line inputs? That will probably be a tall order in that most EQs are not intended to be connected directly with speakers.

I use an inexpensive third octave Behringer unit with the subs in my HT system that would fit your budget, but only has line level input/outputs.

rw

[E-Stat]

You've got a nice list of equipment there....why would you want to add a 'ghetto' piece like an EQ....to a subwoofer no less?
I use a third octave EQ on the subs in my HT system due to a nasty suckout at 100 hz and to provide a subtle lift at the bottom. The room really is too small to use the gaggle of bass traps found in the larger space where my audio system lives.

I wouldn't use EQ, however, full range on the 'stats in that system.

rw

[Woochifer]

How do you have your system connected right now? I'm a bit confused because I don't recall the PW-2200 having any speaker level inputs, and the RSX-972 is an AV receiver with its own bass management and line level sub outs. Don't know why you'd want an EQ with speaker level inputs/outputs. For one thing, I don't know of any that fit that description.

If you can attach a subwoofer to a line level output, then the Behringer Feedback Destroyer is a great bargain -- easy to find for less than $120, lots of people use this model with their systems, and has 12 parametric filters per channel (more than you'll ever use). Keep in mind though that the BFD does introduce audible colorations into the signal path. These colorations are insignificant in the low frequencies, which coupled with the low price is why the BFD is a popular choice among home theater owners. But, they do affect the highs and mids, so if you need to attach this to a setup that uses the subwoofer's line level high pass filter (the PW-2200 cuts off at 80 Hz), then the BFD might not work well.



You've got a nice list of equipment there....why would you want to add a 'ghetto' piece like an EQ....to a subwoofer no less?

Like the others, I'm a bit surprised by this quote, considering your level of knowledge and how well you've done with your own system! All I can say is if you think your system sounds good right now, you'll be in for a huge shock at how much better it sounds after you equalize the subwoofer. With the BFD available on Musician's Friend for $100, this is an insane bargain for the sound quality improvement that it makes.

BTW, my before and after curve with the BFD is shown below. Equalizing the sub eliminated the boomy peaks that my room was creating, and my in-room bass response is now within 2 db all the way down to 25 Hz.


http://members.aol.com/sfwooch/myhomepage/subtest.gif

[audio amateur]

Like the others, I'm a bit surprised by this quote, considering your level of knowledge and how well you've done with your own system! All I can say is if you think your system sounds good right now, you'll be in for a huge shock at how much better it sounds after you equalize the subwoofer. With the BFD available on Musician's Friend for $100, this is an insane bargain for the sound quality improvement that it makes.

hehe he seems to have disapeared all of a sudden. I was quite shocked to be honest.

[jrhymeammo]

How do you have your system connected right now? I'm a bit confused because I don't recall the PW-2200 having any speaker level inputs, and the RSX-972 is an AV receiver with its own bass management and line level sub outs. Don't know why you'd want an EQ with speaker level inputs/outputs. For one thing, I don't know of any that fit that description.

If you can attach a subwoofer to a line level output, then the Behringer Feedback Destroyer is a great bargain -- easy to find for less than $120, lots of people use this model with their systems, and has 12 parametric filters per channel (more than you'll ever use). Keep in mind though that the BFD does introduce audible colorations into the signal path. These colorations are insignificant in the low frequencies, which coupled with the low price is why the BFD is a popular choice among home theater owners. But, they do affect the highs and mids, so if you need to attach this to a setup that uses the subwoofer's line level high pass filter (the PW-2200 cuts off at 80 Hz), then the BFD might not work well.


http://members.aol.com/sfwooch/myhomepage/subtest.gif

Nice curve you got their.
My Rotel is in a box tucked away
Unfortunately, using sub-out and line-out is not an option. I'm using my tube integrated which does not have output stages. My Rotel is in a box tucked away, maybe I should sell it after having a technician clean the unit.
I have my speakers connected from sub's speaker high pass output. I believe my PW2200 is the first one they made, since it doesnt have a version number.

That's too bad, I was getting excited about controlling my lower frequency.

Thanks for all the help though.

[jrhymeammo]

So I ran a sweep test with my setup. Obviously my 6.5" woofers are not capable of playing below 50hz. I thought by using speaker in/out on back of my sub would eliminate sending lower frequency(80hz and below) to my main speakers. Come to think of it, I dont know crap about subwoofer.

[jrhymeammo]

EQing a sub was the biggest topic last year, but I can't recall anyone talking about it anymore. What gives?

It's just lower frequency so the tonal quality isnt that significant. I still don't see why everyone uses it. Since I purchase a preamp( still no amp) the idea of SubEQ has been popping inside of my head again.


Any afterthoughts on this?

Thanks

JRA

[kexodusc]

It's just lower frequency so the tonal quality isnt that significant. I still don't see why everyone uses it. Since I purchase a preamp( still no amp) the idea of SubEQ has been popping inside of my head again.



I would disagree that tonal quality isn't significant. Maybe you've either never heard a good sub, or never heard a bad sub and are taking good sound for granted?

EQ'ing, IMO can produce far more benefit to sound quality than even an upgrade in pre-amp or amplifier. And it certainly doesn't cost nearly as much. It's nice to see more subs are coming with it integrated (though not very well). Someday, every sub should have it built in. It's a necessary function for a sub.

Everybody's room plays a role in preventing the sub from playing like it would in an anechoic chamber, the results are large peaks and booms that force you to do 1 of 2 things when setting the levels and integrating with your mains:
1) set the sub to the loudest frequency bands, in which case a great deal of bass could be 20-30 dB lower in volume, or
2) set the bass to a lower level, in which case you have a large peak across another band that is incredibly distracting, as it drowns out and overpowers the rest of the music. This why a lot of people find their subs boomy, poor for music, and can locate them directionally. They're not set up right!

Bass is important, especially subwoofer bass which accounts for around 2 octaves when best implemented. That's no area to go short on. A good sub, well integrated of quality equal to your main speakers will deliver better, more musical bass than woofers can for a variety of reasons. Most people never take it that far.

I always use speakers as a comparison. You wouldn't own a speaker with a frequency response of +/- 18 dB. Why do you allow that for your subwoofer?

[jrhymeammo]

Good Post Kex, and Oops..




I still don't see why everyone uses it.

JRA

I meant to type "I still dont see why everyone's NOT using it"

Sorry about that... completely different than the way it was intended(I do it all the time).

I dont think it's possible for anyone to own a sub that will produce flat (3+/- dBs from 20-100hz) frequency response, not matter what the spec states.

I wanted to revive this thread for my purpose and others without an equalizer for subs. Is there an alternitive to Behringer FBD since last year for around $200?

Thanks

[kexodusc]

I wanted to revive this thread for my purpose and others without an equalizer for subs. Is there an alternitive to Behringer FBD since last year for around $200?

Thanks

I'm not aware of all the eq solutions that exist out there, but the BFD is still arguably the most cost effective unit. Most other PEQ's I've seen run at $300-$600 and by all accounts units on the low end of that scale aren't as flexible as the BFD, some are said to introduce some noise in the signal. The BFD, if used properly, keeps that to a minimum, and there's lots of free tools available (including a downloadable auto room eq wizard.)

Parts Express sells the latest BFD for $99. You can buy a used one cheaper, but at that price it's hard to beat.

[E-Stat]

It's just lower frequency so the tonal quality isnt that significant.
I will also have to disagree. Getting the first couple of octaves right can help make a system disappear. In my main music system, I achieved that with careful placement of the speakers and a forest of bass traps.


I still don't see why everyone uses it. Since I purchase a preamp( still no amp) the idea of SubEQ has been popping inside of my head again.
Well, I purchased a Behringer EQ for the powered subs in the HT, but no longer use it. Why? It's in a different room now where the issues are above the range of the sub. I tried it full range, but don't like the sonic compromise. So it sits on the shelf.

rw

[Rich-n-Texas]

Good Post Kex, and Oops..



I meant to type "I still dont see why everyone's NOT using it"

Sorry about that... completely different than the way it was intended(I do it all the time).

I dont think it's possible for anyone to own a sub that will produce flat (3+/- dBs from 20-100hz) frequency response, not matter what the spec states.

I wanted to revive this thread for my purpose and others without an equalizer for subs. Is there an alternitive to Behringer FBD since last year for around $200?

Thanks

And I'm glad you did jr. Kex has offered me a lot of advice for my redundant and stupid questions about my subwoofer situation. Had I dug a bit more I would've found this thread and saved everybody from answering the same questions over and over again.

I just wish these vBB's had better search engines.

[kexodusc]

And I'm glad you did jr. Kex has offered me a lot of advice for my redundant and stupid questions about my subwoofer situation. Had I dug a bit more I would've found this thread and saved everybody from answering the same questions over and over again.

I just wish these vBB's had better search engines.

I shouldn't take much credit, if you look back 3 years ago or so I was of the opinion subs should only be used for home theater and never for music, that crossovers should be as low as you could set them (mine was 40 Hz) and didn't really know too much about room acoustics and their impact on bass beyond the fact there'd be "peaks and dips" in the response. I learned a lot from people like Woochifer, Sir Terrence, Dr. Greene etc on this stuff.
Just glad I could share what I've learned, some of those folks are no longer with us here.

[emorphien]

Equalizing my sub might just become an end of summer project now.

[Rich-n-Texas]

...So it sits on the shelf.

rw

For sale??? :ihih:

[jrhymeammo]

I will also have to disagree. Getting the first couple of octaves right can help make a system disappear. In my main music system, I achieved that with careful placement of the speakers and a forest of bass traps.
rw

Well I miss wrote, but I think you knew that.

Without any first hand experience, I would like to speculate this.

I think subs would sound better without EQ, IF bass traps and other acoustic treament can control it. I still imagine that adding EQ will colour lower sound, but probably isnt that big of deal.

If traps sound becomes a huge WAF, then EQ should be on top of the list for everyone who are annoyed with substantial peaks?

My REL T-3 is significantly better than PW-2200 I had. But of course, I never got to try T-3 in my last apartment as well as PW-2200 in my new place.

What I would like to ask is:


Have you tried using your EQ in your main system without traps? If so, what did you know like about it. I have to think EQzer would allow you to fine tune your room response a little easier than carefully treating your room. I just dont see how anyone could make such precise placement that will work better than an EQ. I believe it's possible to achieve... but I just can't believe how you did it. If added coloration was the reason why you chose traps over an EQ, then I can't argue with you. Again, I dont have any experience with this.

Would you care to discuss this a little?

Thanks to all the replies I received to this point.

Peace

[kexodusc]

Without any first hand experience, I would like to speculate this.

I think subs would sound better without EQ, IF bass traps and other acoustic treament can control it. I still imagine that adding EQ will colour lower sound, but probably isnt that big of deal.

You can trap your room until the cows come home, but I would suggest it would make the sound far too dead for music, would cost a small fortune, and still wouldn't solve all the problems. Unless you've got a monster sized room 20 X 30 or something, then it can get a bit easier towards the sweet spot. Most homes probably don't have that. Even then, you're still going to have large, uneven responses throughout the room (if you live in an oval or something you might get away with it). Physics sucks.
Likewise, an EQ only approach might be good at one listening position, but all bets are off the further way you more.
Traps can definitely help. I definitely had to use less drastic adjustments and notice more even respone from 3 of 4 seating areas after I put mine up. The less filters, and the less aggressive the filters, the better for sure!

Everyone always equates EQ's with sound coloration. When we use the BFD, we're typically applying only a few cuts - maybe 3 or 4 tops (some would say that's too much) and maybe, if you're good, one boost of moderate amounts. The fewer, the better. We aren't boosting and cutting throughout. The processing is in an area of the spectrum that our ears are more forgiving with so we can get away with it. I also believe a lot of the noise artifacts simply are beyond the abilty of a subwoofer to reveal, especially harmonics higher in frequency.

[jrhymeammo]

Agreed, but I think I will try it first before making further statements. Hopefully before this year is over.


Your statement about limited effective areas/seating is what I had in mind.

I'm glad Feanor talked me into getting a preamp/amp instead of simpler integrated amps.

Thanks Kex,
JRA

[westcott]

I think many of you have valid points but I always suggest EQ be a last resort and approached with conviction. NO EQ is better than bad EQ. As touched on, lowering humps is acceptable but raising dips in frequency is not generally suggested. E Stat has a good point too. Speaker and subwoofer placement should be the first plan of attack and EQ should be a last resort if all techniques fail like panel placement. Many people think that buying more equipment is always the solution without ever learning about room acoustics, room modes, room setup, seating distances, speaker placement, etc. If you have mastered these fore mentioned topics, then you probably do not need to post a question on a forum as to what EQ device is the best for the money.

The last difficult situation is that most people do not have the equipment necessary to properly measure room acoustics and frequency response. It takes equipment that has a very high sample rate. Most DDS and FFT time window systems that are affordable have a resolution that is greater than or equal to 100Hz resolution (usually 1\3 octave spectral averaging solutions). Q measurements can rise and fall within even 0.5 dB so reliably measuring these frequency changes just is not in the average persons capabilities.

I do not mean to burst anyone bubble. It just is the reality of current technology and without adequate research, you could really be chasing your tail and throwing lots of money at a solution that is not achievable without professional help.

[recoveryone]

Thank you much National Minister of Pertanent Information.

Oh my, let us all bow down to one of the AR masters. Did you just come out of hibernation to grace us with your wisdom T......lol good to see you again old friend.

[GMichael]

Oh my, let us all bow down to one of the AR masters. Did you just come out of hibernation to grace us with your wisdom T......lol good to see you again old friend.

Note the date of Sir T's post.

[Woochifer]

What I would like to ask is:


Have you tried using your EQ in your main system without traps? If so, what did you know like about it. I have to think EQzer would allow you to fine tune your room response a little easier than carefully treating your room. I just dont see how anyone could make such precise placement that will work better than an EQ. I believe it's possible to achieve... but I just can't believe how you did it. If added coloration was the reason why you chose traps over an EQ, then I can't argue with you. Again, I dont have any experience with this.

Would you care to discuss this a little?

Thanks to all the replies I received to this point.

Peace

Personally, the best setups I've heard incorporate a combination of placement, calibration, room treatments, and EQ. In my room, I use acoustic panels, but they are more for blunting front and side wall reflections. As of now, I don't have any bass traps installed and only use a parametric EQ. The reason is the WAF (the homemade bass traps look like arse) and the cost for commercial bass traps.

From my experience, I can tell you that equalization alone made a dramatic improvement in my sub's in-room performance. The subwoofer's tonal characteristics varied dramatically depending on where I placed it within my room, but no matter what location I picked, I measured at least two very large frequency peaks. While room treatments can reduce the magnitude of these wave interactions, treatments alone cannot eliminate them in a typical room. As Kex said, physics sucks.

EQ by itself is an imperfect solution for any number of reasons (only works at one seated position, introduces delay, etc.), but I think that in conjunction with proper placement and calibration, EQing can significantly improve the performance for just about any subwoofer in a typical room. In going with treatments and EQ, it's not an either/or proposition. Both approaches by themselves are preferable to doing nothing (sure no EQ is preferable to bad EQ, but properly applied EQ can be much preferable to no EQ depending on your room acoustics). And ideally you'd want to get your placement, calibration, and room treatments optimized before using the EQ to fine tune the larger problems that cannot otherwise be corrected.


The last difficult situation is that most people do not have the equipment necessary to properly measure room acoustics and frequency response. It takes equipment that has a very high sample rate. Most DDS and FFT time window systems that are affordable have a resolution that is greater than or equal to 100Hz resolution (usually 1\3 octave spectral averaging solutions). Q measurements can rise and fall within even 0.5 dB so reliably measuring these frequency changes just is not in the average persons capabilities.

People familiar with the Room EQ Wizard (http://www.hometheatershack.com/roomeq/) would probably disagree with this statement. All that application requires is a PC with a sound card and a Radio Shack SPL meter (the mic calibration file is built into the application) along with some rudimentary RCA cabling and 1/4" jack adapters. And it's an open source freeware application. The application includes an automatic calibration function that identifies the best attenuation settings (both center frequency and bandwidth) for a parametric EQ, and it can be used to measure the frequency and time response.

For purposes of subwoofer equalization, you don't need measurements that are reliable to within 0.5 db, and just plotting the frequency response with test tones and a $40 Radio Shack SPL meter will give you enough data points since the EQ filters used with a subwoofer will rarely need anything beyond a 1/12 octave bandwidth. This is not a full spectrum measurement, so the kind of precision you're talking about is not necessary here.

[recoveryone]

oops the thread is almost a year apart lol

[E-Stat]

The reason is the WAF (the homemade bass traps look like arse) ...
Hmmm. I guess it depends upon whose arse to which you refer. Say, Kristanna Loken's fine example as seen in T3 where she approaches the chick in the Lexus convertible? ;)

Seriously, they don't have to look bad. Although my listening room is one of two WAF free zones in my house (the other being the garage), I wanted an attractive living space myself. I did have to barter with my wife to make all the socks though! Unfortunately, we couldn't find enough gray spandex so one of the four traps in each of the back corners is black.

http://home.cablelynx.com/~rhw/audio/traps_left.jpg

http://home.cablelynx.com/~rhw/audio/traps_right.jpg



For purposes of subwoofer equalization, you don't need measurements that are reliable to within 0.5 db, and just plotting the frequency response with test tones and a $40 Radio Shack SPL meter will give you enough data points since the EQ filters used with a subwoofer will rarely need anything beyond a 1/12 octave bandwidth. This is not a full spectrum measurement, so the kind of precision you're talking about is not necessary here.
Agreed, but not limited to subwoofer placement either. I used a SP test CD, RS SPL meter and calibration curves to fine tune the placement of my 'stats, room treatments, and couches for the smoothest response in the bottom three octaves.

rw

[westcott]

You have to work with what you have but Q resonances are there and do peak in areas way beyond the ability to measure them with typical hardware. Just because you have never heard of these issues does not mean they do not exist.

I think you need to read the attached pdf and if you do not want to read the whole thing, skip down to page 17, 18, and 19 to understand what I am referrning to.

Q resonances affect timbre and pitch, depending on the frequency range and in the case of subwoofers, timbre is the major problem.

Dr. Floyd Toole - Audio Science (http://www.harman.com/wp/pdf/AudioScience.pdf)

[Woochifer]

Hmmm. I guess it depends upon whose arse to which you refer. Say, Kristanna Loken's fine example as seen in T3 where she approaches the chick in the Lexus convertible? ;)

Seriously, they don't have to look bad. Although my listening room is one of two WAF free zones in my house (the other being the garage), I wanted an attractive living space myself. I did have to barter with my wife to make all the socks though! Unfortunately, we couldn't find enough gray spandex so one of the four traps in each of the back corners is black

Okay, I take it back (those DIY traps in your pics do not look like the kind of arse I was thinking of -- very nice! :ciappa: )! I should have phrased it differently. DIY traps would look like arse if I tried building them myself!


You have to work with what you have but Q resonances are there and do peak in areas way beyond the ability to measure them with typical hardware. Just because you have never heard of these issues does not mean they do not exist.

I think you need to read the attached pdf and if you do not want to read the whole thing, skip down to page 17, 18, and 19 to understand what I am referrning to.

Q resonances affect timbre and pitch, depending on the frequency range and in the case of subwoofers, timbre is the major problem.

Thanks for clarifying. I did not realize that you were referring to the time domain, which I do know that EQs can distort.

But, within this context, if the Q resonances are beyond the ability of end users to measure, then are you suggesting that EQs be avoided altogether, even if their corrections to the frequency domain are easy to measure and hear?

[kexodusc]

You have to work with what you have but Q resonances are there and do peak in areas way beyond the ability to measure them with typical hardware. Just because you have never heard of these issues does not mean they do not exist.

I think you need to read the attached pdf and if you do not want to read the whole thing, skip down to page 17, 18, and 19 to understand what I am referrning to.

Q resonances affect timbre and pitch, depending on the frequency range and in the case of subwoofers, timbre is the major problem.


Figures Toole would work his way into this conversation.

You're only considering the "Q-resonances". What about non-Q resonances?

Toole's point was NOT that low-Q resonances are more important for subwoofers than high-Q resonaces. In fact, Toole even states in his paper that at low frequencies, all bets are off on the audibility of the thresholds of resonances (think Fletcher-Munson). When we factor in the human ear's sensitivity to frequencies in that range, it's just the opposite. The issue isn't the Q-factor, high or low, for frequencies below 100 Hz especially, but rather the relativity intensity of these resonances compared to the reference level.

Small resonances of various Q of course exist in the lower octaves. I don't think Wooch or anyone else is denying EQ'ing won't solve a small, low-Q peak of 0.25 dB with a Radio Shack SPL meter and BFD. We may argue the magnitude of impact on the sound quality, timbre, and pitch a low-Q resonce has when one considers the human ear's senstivity to frequencies below 200 Hz.

I have yet to see any rational argument that supports not using an EQ to deal with low, medium, or high Q resonances of larger sound pressure levels (say +6 to +9, even +12) that are present (and there are some nasty, strong low-q resonances quite often), inevitably after room treatment and proper speaker placement in most homes, and which are quite easily captured by sine wave test tones in 1/6 octave increments, and sweeps on conventional equipment.

[E-Stat]

I think subs would sound better without EQ, IF bass traps and other acoustic treament can control it.
Agreed.


Have you tried using your EQ in your main system without traps?
Oh yes.


If so, what did you know like about it.
First of all, my main system uses full range electrostats, so I cannot selectively use it only with sub(s) like I have done in my HT. Where do I start? Added false brightness. Soundstage gets narrower and shallower. Resolution suffers. The sense of musical delicacy, detail, and effortlessness I've spent years to achieve goes out the window in one swell foop.


I have to think EQzer would allow you to fine tune your room response a little easier than carefully treating your room. I just dont see how anyone could make such precise placement that will work better than an EQ.
Perhaps. Remember skeptic / Soundmind? He once said that it takes him two years to get his system adjusted with his three EQs. I spent the better part of a day running about two dozen trials varying position of speakers, traps, and listening couches. I get 30-200 Hz +/- 1.5 db with a 2 db peak at 25 hz. The result sounds neutral enough to me without butchering the signal.

I purchased my current EQ (a Behringer unit) specifically for my HT subs. The room in my previous house had a huge 100 hz suckout and a 160 hz peak that I wanted to fix. Limited to subs, I think they work very well.

rw

[westcott]

Dr. Toole's paper clearly states at the bottom of page 18, that I refered to earlier, that
........... "at very low frequencies, the long wavelengths and periods allow ringing to be heard as an extension to bass sounds - boom."

The conventional method of specifiying frequencies is useless..... and 0.5dB variances can clearly be heard at all frequency levels (high or low) equally. Once again, at the bottom of page 18.

I point these things out so that others can view things from both sides of the fence. Whether you agree or disagree with Dr. Toole, it still points out that many experts in the field suggest EQ be used with prudence and that its affects are far more wide ranging than most people are aware of.

[kexodusc]

I point these things out so that others can view things from both sides of the fence. Whether you agree or disagree with Dr. Toole, it still points out that many experts in the field suggest EQ be used with prudence and that its affects are far more wide ranging than most people are aware of.

I don't disagree with him at all, and I agree with your recommending using EQ's with caution - good advice. Though nobody here is suggesting anyone go trigger happy with an EQ.

I could be off, but your earlier you seem to take what he wrote about the total spectrum, in specific reference to loudspeakers and conventional FR testing methods in and applying it to subwoofer equalization in a very specific, low frequency range. It's a bit trickier than that.

I can quote him too (p.17):

"High-, medium- and low-Q resonances shown at the detection thresholds, below which the resonances cease to be audible. It depends on what you are listening to. The locations of the illustrative peaks on the frequency scale are arbitrary. The audibility is similar at all frequencies except, perhaps, at very low frequencies."

We are less sensitive to low frequencies. Much less.

What you've said about EQ'ing is good advice - use it after you get all your other affairs in order. All I'm trying to point out is that while we can't achieve perfection, using an EQ to eliminate the remaining, really bad problems, can still get us closer to the goal.

RE: the time domain - this is where my comfort level drops significantly, except that I do know if you're experiencing problems with FR because of room acoustics, you're undoubtedly experiencing problems with the time domain as well. The risk, I suppose is that you'll make it even worse. In practice, we find that you're improving the FR at a greater "rate" than you're further worsening the phase/time interference, which should result in a net benefit. Of course this probably isn't always the case, and that's where listening comes in. If you apply a filter and it sounds bad, don't use it.

[jrhymeammo]

Thanks to all for replies and insights.

I guess this site isnt dead after all.

Thnx

[PeruvianSkies]

Positioning the subwoofer proves to be one of the most challenging in a home theater setup, mainly because it's exact position is unlike the others. A center channel placement is dictated by it's purpose, which is provide sound between your left and right channels. So how about a subwoofer? I've heard various things over the years as far as where the 'best' place is. The other thing that needs to be a factor is not only the best stop, but whether or not the room permits for that spot as well as the design of the room. In most cases, that is fairly standard or a common size. Also can depend on if you have a dedicated room or not. For most people though the sub is placed in a spot that is available and then room acoustics or treatment is done to accomodate. My sub is positioned in the only available front corner of my room and is positioned in such a way to benefit the most from the corner. I also added some sound panels nearby to help keep a nice bass response through the entire room. In order to achieve this I simply messed around with settings until I reached a point where I couldn't pinpoint WHERE the bass was coming from in the room. I've noticed when listening to most peoples setups that I can always tell where their sub is, even without seeing it and that should NOT be the case. A good sub with good placement and levels should just 'fill' the listening space, as well as blend with the other speakers with proper crossover.

[kexodusc]

Positioning the subwoofer proves to be one of the most challenging in a home theater setup, mainly because it's exact position is unlike the others. A center channel placement is dictated by it's purpose, which is provide sound between your left and right channels. So how about a subwoofer? I've heard various things over the years as far as where the 'best' place is. The other thing that needs to be a factor is not only the best stop, but whether or not the room permits for that spot as well as the design of the room. In most cases, that is fairly standard or a common size. Also can depend on if you have a dedicated room or not. For most people though the sub is placed in a spot that is available and then room acoustics or treatment is done to accomodate.

Good points. We tend to only discuss "subwoofer placement" when really we should be discussing bass transducer placement. Invariably, the best place for the bass reproducing part of your system is not the best place for your main speakers. The same room acoustic problems that plague a sub, plague your main speakers as well. Problem is, I have a hard time physically separating my towers by frequency. This one huge advantage a properly integrated subwoofer(s) can provide over traditional 2-channel rigs.



My sub is positioned in the only available front corner of my room and is positioned in such a way to benefit the most from the corner. I also added some sound panels nearby to help keep a nice bass response through the entire room. In order to achieve this I simply messed around with settings until I reached a point where I couldn't pinpoint WHERE the bass was coming from in the room. I've noticed when listening to most peoples setups that I can always tell where their sub is, even without seeing it and that should NOT be the case. A good sub with good placement and levels should just 'fill' the listening space, as well as blend with the other speakers with proper crossover.

There's a few things going on here that cause the sub to give away its position.
First - a lot of receivers still only use 12 dB/octave LFE filters, which really sucks, especially common on entry level and still found in some mid-fi systems. Most HTIB's where the xo is likely defaulted or fixed at 100 Hz because the satellites have poor response below that. The sub is still making a good chunk of noise above the crossover point. Even at 80 Hz as a crossover, you're getting output from your sub at significantly audible levels at higher frequencies where the bass is directional. Harmonics and overtones of the fundamentals can be audible as well. I think THX certified receivers use 24 dB/octave filters, I've seen some that go as high as 36 dB/octave, which is even better IMO. This is partially why everyone always recommended the crossover to be as low as possible originally - say 60 or even 40 Hz. Way back we were stuck with 12 dB/octave filters and 90 Hz as our only option. No wonder subs were easy to find. Super low xo's are not as necessary and often not even optimal now.

A lot of subwoofer cabinets suffer from resonances too which can betray their location.

I have an old S&V mag with an article that also suggest our brains work against us here too. I'm no expert in the human senses, but the article suggested that our ears hear the frequency, and while they can't always localize it, we also feel the vibrations and sound pressure and the brain puts 2 and 2 together to try and "guesstimate" it. Doh!

It's definitely not easy to integrate a subwoofer well.

[weatherby]

Hello all. New to this forum. I recently purchased a BFD to help equalize my two SVS subs. I am very confused how to store the changes I make. Here is what I am doing: I select the frequency say 20hz then I apply the gain or cut then I push the store button once and it flashes then I push it again. It seems to work until I change the next frequency say 25. After I go through that routine sometimes my previous setting for the 20hz has changed as well. Can someone tell me how to do this to get the best flatest fr for my sub?
Thanks.

[Woochifer]

Hello all. New to this forum. I recently purchased a BFD to help equalize my two SVS subs. I am very confused how to store the changes I make. Here is what I am doing: I select the frequency say 20hz then I apply the gain or cut then I push the store button once and it flashes then I push it again. It seems to work until I change the next frequency say 25. After I go through that routine sometimes my previous setting for the 20hz has changed as well. Can someone tell me how to do this to get the best flatest fr for my sub?
Thanks.

Before you make a setting for a different frequency, you first need to create another EQ filter. There are a total of 12 EQ filters available for each program. Before you get started, you should probably use program #4 because all 12 filters are preset for "PA" (parametric) mode.

The procedure is pretty simple. Since you already set a parametric filter, and stored it into memory, all you need to do is hit the "FILTER SELECT" button and move the jog wheel until you see the LED indicator move up to filter #2 (assuming that you selected #1 to do your first EQ filter). Then, you simply repeat the steps that you used to create the first EQ filter, and store it into memory. At this juncture, you should see two LEDs lit up. This means, that you have set 2 EQ filters.

Here's a link with more detailed instructions.

http://www.hometheatershack.com/forums/bfdmeasure/

[weatherby]

Woochifer thank you very much. That makes a lot of sense. Why couldn't the manual have said that. Also thanks for the link. I came across that last night and the BFD guide looks like it will be very helpful.
Again thanks.
Ed

[Woochifer]

Woochifer thank you very much. That makes a lot of sense. Why couldn't the manual have said that. Also thanks for the link. I came across that last night and the BFD guide looks like it will be very helpful.
Again thanks.
Ed

The BFD became a popular choice for subwoofer EQing more in spite of Behringer's efforts than anything. First and foremost, the BFD is intended for live sound applications as a feedback reduction device. It was not designed for home use, and the manual, rack-centric design, and convoluted controls reflect that. The parametric EQ function on the BFD is basically a secondary feature.

The benefits of subwoofer EQing have been known for a while, but until the BFD came along, parametric EQs generally cost at least $300. With a list price of $129, word on the BFD spread quickly on this forum, Home Theater Forum, AVS Forum, and others. The instructions and tips on how to use the BFD with a home theater developed rapidly and without much input from Behringer. It's amazing to see how many people took these online pointers and ran with them; and the near universal agreement on the merits of the BFD for subwoofer EQing is just as remarkable considering how fractious audio hobbyists in general can get.

I'm actually surprised that you got as far as you did just with the manual! Sonny Parker's BFD Guide/Home Theater Shack is a great resource for learning how to use the BFD. People on this forum introduced me to the BFD, and Sonny Parker's site easily provided the best instructions on how to use the device.

The last five or so years have seen a remarkable wave of calibration and equalization tools specifically for subwoofers. These newer devices include some useful features and are much easier to use than the BFD. But, the BFD remains popular simply because of its rock bottom price, and large community of knowledgeable users.

[kexodusc]

The last five or so years have seen a remarkable wave of calibration and equalization tools specifically for subwoofers. These newer devices include some useful features and are much easier to use than the BFD. But, the BFD remains popular simply because of its rock bottom price, and large community of knowledgeable users.

And let's not overlook the obvious...it's a damn fine looking piece of equipment. I can't wait for the faux woodgrain option.

[weatherby]

Again thanks. I am just glad I stumbled along this web site and the BFD Guide. Thank goodness for Google. I have been a long time member of AVS but just had not seen it mentioned there. Thanks again for the input. I am leaving tomorrow for Hawaii for a week (lucky me) which means I won't be able to do any tweaking until I get back. You know somthing is wrong when you would rather tweak your sub then go to Hawaii....;o)

[fresh954]

This might seem like a dumb question, but ill ask it anyway. I have a pioneer reciever with Multi-Channel AcoustiC Calibration System (MCACC), basically have to place a microphone in my listening postion and the system plays tones a different levels and adjusts accordingly. With that said, Would I benefit from a Behringer Feedback Destroyer or did the Pioneer's Calibration system already smooth those LFE's out?

:cornut:

[GMichael]

This might seem like a dumb question, but ill ask it anyway. I have a pioneer reciever with Multi-Channel AcoustiC Calibration System (MCACC), basically have to place a microphone in my listening postion and the system plays tones a different levels and adjusts accordingly. With that said, Would I benefit from a Behringer Feedback Destroyer or did the Pioneer's Calibration system already smooth those LFE's out?

:cornut:

Most receivers do not calibrate below 80 htz. Base is the hardest part to get right.

Not a dumb question at all.

[fresh954]

Thanks for the reply. I went ahead and placed an order with Parts Express, so it should arrive by Wednesday next week. Hopefully its easy to setup. Thanks for the reply.

[greensleev3s]

Hi. I'm new to this site, and have become interested in this discussion of sub equalization.
A lot of people have written about the BFD, and it is still widely available.
Would using the BFD be possible with my current setup?

NAD C370 integrated amplifier
Polk Monitor 70's (Bi-wired)
Polk PSW505 subwoofer (connected from NAD pre-out 2 with RCA cables)
iPod with dfx enhanced mp3s
Sony DVD/CD player

Thanks very much

[JoeE SP9]

Hi, and welcome to AR. The answer to your question is yes. Connect it between your pre outs and sub.

[greensleev3s]

Thanks very much for the quick response. The plot thickens!

[GMichael]

I understand that a BFD can not be set up without a laptop (or a computer in the HT room). Is that true, or does it just mean that it would need to be set up manualy?