[Danberg]

Never having, or previously wanting a subwoofer for my two channel audio system, I've decided to find out basic information about them before making the decision into purchasing one.

I am seriously interested in purchasing a new set of speakers and want to integrate them with a sub (ONE sub, NOT two of them).

At what frequency will a sub's location become apparent?  It's placement in the room requires that it will be very close to one speaker.  I definately do not want it's location to be audibly noticeable.

Lets say the main speakers bass response drops off at;
50hz.  
What would the recommended cross over point be on the sub?

40hz.  
What cross over point recommended?

30hz.
What cross over point recommended?

What rule of thumb do you use for setting the sub so that it properly integarates with the main speakers?  Does the steepness of the main speakers frequency drop off have any bearing on the choosen cross over point of the sub?

Does a sub allow you to hear individual notes plucked on a bass guitar or is the bass simply present as something you get the sensation of "feeling?"

I listen mainly to oldies rock, female vocals, current country and no classical.

[Rob Babcock]

It's best for music to cross the sub over as low as you can without taxing your mains.  60 hz works well for most speakers.  If you have very small monitors you may to go a little higher; with large floorstanders you can probably go lower.  I wish I could say there was a magic formula (eg "cross them over 20 hz over the bottom linear range of the mains")- in reality it's not so cut and dried.  You almost don't know how complicated is the question you ask; there's a lot of differing opinions.  A lot of people don't use a low pass, preferring to let the mains roll off naturally, and "bring the sub up under" the mains.  To me that's the wrong approach, as that doesn't really reclaim any lost dynamic range like you will by freeing the mains of that bass.

Most people will advocate placing your sub (if you use just one) in the center right between your main speakers.  That way if you get any localization of bass sounds they'll appear to emanate from the same area as the music.  This isn't a bad idea, although if you keep the x-over point low you can experiment with a variety of locations.  Behind your listening position can work, and nearfield placement often works well, too.

The steepness of the crossover legs can vary depending upon your speakers, but it's often a fixed value.  The lowpass feeding the sub will need to be rather steep to avoid localization, often 18-24 dB/octave.  The high pass feeding the mains will often be 12 dB/octave.  It just depend on what you're using.

One major plus with a sub is being able to not only place the sub where it can produce the best bass, but also being able to apply EQ to the bottom octaves without messing with the other ones.  You can apply parametric EQ to knock down a large response peak in the bass without mucking up the mids.  And nearly all rooms have irregular response down under 80-100 hz.

Yes, a sub will give you the pluck of the bass, the thud of the bass drums, etc.  But often the most surprising gain you get is a sense of "presence", a feeling of the size of the space the recording was made in.  It's hard to describe, but you'll get the atmosphere of the recording venue, the sense of "pressurization," if you will.  If your mains already go very deep, there may not be a huge diff, but very few speakers can go as low as a good sub, almost irregardless of price.  Provided you take care to integrate it well, a good sub has no drawbacks, only advantages.

[mcgsxr]

I think that Rob has objectively stated the facts around subs, and touched on the subjectivity of implementation, which is where it gets complicated.  I think that people experience results that please them, in their room, with their gear, and then lose sight of how subjective that is, and that is what leads to many of the "heated" discussions around how to involve subs.

I have 2 subs, and am likely to build 2 more in the coming months.

Now that you have stopped laughing, and for many, stopped reading, I will continue with what I can clearly admit is a subjective experience with my toys, in my place.

I run a set of small monitors, Totem Rokk for the record, and use all DIY subs.  I get great results with the REL concept of running the mains full range, and pulling in the subs underneath their natural cutoff.  Rob is bang on the money that I am not regaining whatever lost dynamic ability my Totems lose in producing bass down to their limits, but that is simply not a concern of mine - I don't want it all that loud, I simply want it deep, and for me, doing it this way, with this gear, works.

I place my ported movie sub directly behind me, about 4 feet behind my chair, with the mains about 7 feet in front of me.  I place my sealed music sub directly beside the left main, in the plane of the speakers, 7 feet from me.

Both subs use (one at a time) a 300w BASH amp, running a line level (RCA) input from my B&K pre/pro.  I swap the speaker cables from amp to chosen sub, depending on the music or movie selection at the time of listening.

The sub amp has a built in Xover, that I use to keep the sub playing below 50Hz.  The Totems are reputed (optimistic manufacturer perhaps) to play down to the mid 40's, but I find they drop off quickly below 60Hz.  For me, by bringing in the sub at 50, it integrates well with the roll off of the Totems, and ends up sounding pretty flat.

Sure, there are peaks etc, and I bet that running the mains through the Xover could be made to work etc, but for me, I like it this way.

I mentioned that I am hoping to build another set of subs in the future, and these I intend to run integrated as part of the mains, and then let the other sub (ported or sealed) do the .1 thing.  For this implementation, I intend to use one sub amp per sub as the L and R mains (ie a sub and amp as the stand for each main speaker, and filtering at a point determined by the sub Xover) as I hope to go single driver, no Xover for the mains...

Right, clearly a tangent there....

I would advise that you read lots, ask lots of questions, filter a lot, and then play around a bit.  If you have a friend with a sub, perhaps you could borrow it for a week, and try running the configs different ways, and see what sounds good to you - that is what we are all after.

Hope it works out,

Mark in Canada

[Psychicanimal]

Subwoofer(s) setup(s) take(s) a big percentage of an audio system's budget .  One sub doesn't really cut it.  Forget it.  You'll  fall short of doing it right and still end up paying a lot of money--be warned.  My setup uses Dan Wright modded Swans M-1 mini-monitors (4" dual magnet Kevlar/paper woofers), a Dan Wright modded Marchand X9 Deluxe x-over, classic Kenwood monoblocks and NHT subs.  One day while dusting, I mistakenly popped the mono sum switch in the x-over.  When I was listening to music the soundstage was way smaller and I didn't know what was going on till I saw the switch in mono sum.  Even with two subs, if they're operating in mono you'll lose a lot of imaging.

My subs have a  x-over frequency of 80 Hz @ 24 dB/oct.  Since my woofers are very small I want to relieve them of low bass.  They still deliver usable bass (-3 dB) to about 40-45 Hz and 80 Hz is a good spot.  I might try higher points, but don't see a need right now.  My subs are undetectable...

[Danberg]

Rob B., MCGSXR, Psychicanimal, thanks for all the information.  I am a bit surprised with Psychicanimal's comment of "not to waste my money" in considering using one sub.  Unfortunately, the budget only allows for the purchase of one sub now.

Not to start a disagreement , but do do you Rob B., and MCGSXR agree with him and why.

Years ago I did borrow a powered sub from a friend and attempted to use it in my system.  Don't recall the brand, but it was very inexpensive (around $80 to $100 new as I recall).  It had several adjustable turn over points, 150hz, 100hz and 70hz, as I remember.  No matter how I played with its three crossover points, volume setting, and placement, I always could distinuish its's location in the room, either immediately, or at best, within several minutes of listening to music.   Does your experience confirm this?  Or, do you think it was ithe inexpensiveness of the product?  I also recall the volume level adjustment was rather course, going from not being able to hear it to a rather rapid  increase in volume.

My room listening room doubles as our "formal living room" and furniture placement is one that cannot be changed (keeping the better half happy!).
My audio equipment is centered on a 15'9" wall between the speakers in a wood cabinet, 5'-0" wide x 4'-6" tall x 1'-6" deep.   The speakers sit fairly close to the room corners on that same wall.  The speaker fronts extend out 2'-0" from the front of the cabinet.  The listening position is on a couch centered on the oposite wall aproximately 13' from the speakers (couch is against the wall).  
A single sub's placement can only be;

1. in the area between the equipment cabinet and right speaker (to the left, there is doorway between the cabinet  and left speaker).

2. To the right of the couch and against the wall.

3. To the left of the couch, in the left corner and against the walls.

Per Psychicanimal's suggestion of sub(s) placement centered between the speakers and behind the couch are not possible.

Also, I intend to use left and right inputs to the sub.  Would that have any bearing regarding example of the sound stage becoming "smaller" when his sub was accidentally switched to the "mono" position?

Should I start looking at powered or un-powered subs?

Where do I find info on DIY subs?  Any particular brands of powered subs recommended that I look for on Audiogon, if the general consensus is I need 2 subs?  What about the crossover's you speak about?

[Rob Babcock]

I'm a big believer in passive (unpowered) subs.  I realize there's a lot of good powered ones out there, but my luck with them has been bad.  The problem as I see it is that the inside a sub enclosure is a terrible invironment for a sub; there's a lot of vibration & it's tougher to dissipate the heat.  You'll often see that the average powered sub my warrant the driver for 3-5 years but the electronics for only 1 year.  With a passive sub, the electronics can be safely situated back on your gear rack, away from the pounding & vibrations and in free space where it can stay cool.  Flexibility is another advantage to a passive sub- you can drive it with any suitable amp you happen to have around, and adding EQ or DSP is easy.

As far as "needing" two subs- well, I do think 2 is better than one.  I don't think I'd go so far as to say that going with one is a waste of time, though.  You could certainly start with one and add a second as your budget permits.

Regardless of the crossover frequency, there's a very short list of very cheap subs that don't suck.  I recall one AC'er raving about a fairly cheap Yamaha sub, but I can't think of any under-$400 sub you'd want (DIY models excepted).  I guess SVS makes a sub slightly under $400, although it's passive & requires an amp.

[rosconey]

just buy a vmps large sub kit and find a used amp of 100 wpc or more-
they are adjustable with putty on the passive radiator, run it in stereo


i have 3.5 waystand mounts that run full range(down too about 70) and the sub crossed at 90. cant detect where the  bass sound comes from with sub behind mains and to the right side in the corner.

vmps sub was easiest to intigrate of all the subs i ever tried-seamless

[mcgsxr]

OK, firstly I will say that we are all right.  Not possible?  Sure it is, that was the point of my whole subjective/objective phrasing earlier.

For some, one sub will never do, can always be located by ear, and ONLY two subs will do.  For others, myself included, it can certainly be done with one sub to MY satisfaction - perhaps my hearing does not measure up, or perhaps it is my gear that is not good enough - whatever, I love this stuff more than is sane, and perhaps as much as the next guy, (plus I could rant about my formal classical musical training, or list the instruments I have played etc).  To me it is all a big waste of time, IF I am only trying to prove that I am right.

I am not trying to prove that, so I will continue.  I am trying to convey that each listed suggestion is valid, as each person can validate the results in their own system - the only darn system that matters to most I should think!

So, for me, a single sub, especially a sealed sub, can be integrated with mains, and sound good.  One excellent way to do this, would be to place it just to the side of one of your mains, and listen to it.

The Xovers mentioned could relate to such separate boxes as the ICBM from Outlaw, or the Mirage box, or there are other such line level devices - they are attached between pre and amp, if I am not wrong, and allow one to trim the signal to the mains, and sum it for the amp that drives the sub.

There is another way to skin that cat (oh, now that's not very nice... ), and that is to use a dedicated sub amp - this is what is usually tucked into the back of a powered sub box, that actually drives the woofer.  Now, they are USUALLY inside the box the driver (woofer) is in (that is what people refer to as a powered sub) but can be mounted outside the box.  This is what I have done.  I have a 300w sub amp (ie a plate amp that is found in OEM powered subs) that is mounted in a box all by itself, in my wall.  That amp receives a line leve signal from the processor, and drives either my sealed or ported sub.

This is one cheap way to build a DIY passive sub - the amp lives in one box (wherever is convenient for you, and your cabling needs) and the woofer lives in another box, configured to make the BOOM where you want it.

I prefer passive subs, for the reasons already listed by Rob - keeps Mr Amp away from bad old Mr Vibrations....

Also, I am a cheap wanker when it comes to bass (since I cannot afford an REL Stadium, Paradigm Servo 15, VMPS Larger etc) I build my own.  Adire has kits, as do many other places.  This allows me to get what I think is a great driver, and mate it up with a powerful sub amp.

Another way to build a passive sub, is to use a regular amp (any leftovers from previous systems?) and feed it a sub signal - that is where you need either one of the crossover boxes mentioned earlier, or a pre/pro that does that for you.

Now, what about phase?  One of the advantages of using an actual sub amp, is that you can vary the phase of the sub, to assist in the manner in which it does blend with the mains - not easy to do with an external processor, or even with a pre/pro.  By vary, I don't just mean 2 positions, there are sub amps that allow smooth variation of the phase - I don't have one, mine just does + and -, and I have played around to get that right too.

In what I am reading from your post, you have a simple 2 channel system, so I would recommend (for ANY number of subs you wish to configure) a passive sub, regardless of how you end up configuring it.

As for your placement question, in your case, for one sub, I would drop it down next to your right main, and gear cabinet, and have a listen.

For two subs, I would try one on each end of the couch...

Does that help?

Mark in Canada

[lonewolfny42]

I recall one AC'er raving about a fairly cheap Yamaha sub, but I can't think of any under-$400 sub you'd want (DIY models excepted)

I believe that was audiojerry....might send him a PM for info. [/list:u]

[Psychicanimal]

I recall one AC'er raving about a fairly cheap Yamaha sub, but I can't think of any under-$400 sub you'd want (DIY models excepted)

I believe that was audiojerry....might send him a PM for info. [/list:u]

Doug S. bought a couple Yamaha subs after he took off to a smaller apartment.

Danberg:

What I told you is not to create controversy nor confusion.  Too bad I moved from Toledo ( ) last week.  You could have listened to my setup and experience what I'm saying.  Seamlessly integrating subs is HARD.  There's no way around it.  I listened to just mini monitors for decades before taking the plunge and adding subs.  I was going to do it right or not at all.  Steve Rothermel of Ridge Street Audio came to my place one day and positioned my speakers and subs.  He says the subs must be in an arc that intersects the monitors and the subs are to be either inside or not farther apart than 60 degrees from each monitor.  The electronic x-over is critical for seamless integration and that's why Phil Marchand makes special electronic x-overs for subs, like the one I have.  The damping pots are essential for proper integration.  With the Mapleshade Reggae CD I would get bass soundstage of around six feet tall!!!

I think you're rushing into an area you lack knowledge and experience.  It's better to do your homework, listen to a few setups and decide on a strategy.  Everything the others have posted is correct, but the information is application specific.  You will need more knowledge in order to make sound decisions (sound and finantialwise).

Marchand's website is an excellent place to start reading:

http://www.marchandelec.com

[lonewolfny42]

PA makes a good point...take your time , read and listen well, and don't waste more money than you have to. Good luck !!

[Rob Babcock]

Audiojerry actually dumped some very expensive subs in favor of the cheapo Yammies.  It took him awhile to convince everyone it wasn't an April Fools thing!   I dunno if they're giant killer subs or if it's just a freakish case of synergy with his particular room.

[JohnR]

Danberg, is your budget $400? The Adire Audio Rava is considered to be very good at $400. If you are interested in making your own, there are a lot of drivers and other options available. Danny at GR has a new one that looks good:

http://www.audiocircle.com/index.php?topic=11564

[doug s.]

i lurked on the diy bass list for two years before taking the subwoofer plunge.  what i learned there, plus personal experience in the meantime, made me come to a few conclusions:

-two subs, placed for soundstaging not reinforcement, is best.

-passive subs w/outboard electronic x-over is best.

-if you have to use one sub, it must be *exactly* centered between your monitors.  even if crossed over w/steep slope at low frequency, you *will* be able to hear it otherwise.  nearfield location for a single centered sub is even better. (think foot-stool.)

-a big advantage to using an outboard x-over is limiting the low frequencies your monitors will see - this far outweighs any possible negative of an active line-level component being added to the chain that your monitor sees.

-you will not do any better than vmps subs w/a quality active x-over & s/s amp, unless you're prepared to spend close to five figures.  (or more!)   unless you wanna diy - then it will likely only cost twice as much!  
=====================================

here's a pic of my old set-up (yes, personal situation means i no longer get to hear this.     )



that's a big room; even w/a pair of larger vmps subs, there is rarely enough bass to energize the room.  (even a pair of floorstanding speakers i have, w/10" woofers, rated to only 28hz, energize a ~14x18 room more.)   but the bass is quality is *amazing*.  and, w/the right software, the room *will* energize.  websters' unabridged, on the right sub, has ended up on the floor a couple times...  for those bass freaks that want their big rooms shaking all the time, i'm sure sliding the subs back against the rear walls, instead of ~6' out into the room, will help.  

psychic animal is correct - presently i am using a pair of yamaha yst-sw305's.  i had to buy them used - no longer made.  too bad - they really *are* decent subs.   (and the pair cost me <$400, shipping included.)  i bought them based upon audiojerry's recommendation of the smaller yst-sw205's, which only have one servo-driven 8" driver; the 305's up the ante w/two 8" drivers.  in my present rig, these are just *inside* the monitors, w/the x-over point set at 45hz, the monitors are run full range.  this is not ideal; but i haven't splurged for another active x-over yet.  even tho the yamahas are powered, i *will* eventually hook 'em up to an outboard x-over, so i can cross over my monitors.  i will set the active somewhere around 50-70hz, & set the yamaha's x-over to its max 150hz position.  this set-up is presently quite nice in its ~15x22 room.  it energizes the room more than the vmps set-up in the big room, but isn't as palpable.  i suspect this would improve if/when i go to an outboard active x-over...

another decent powered sub that i've recently experienced is one made by defiinitive technology.  don't know the model; it has a 12" driver...  picked up on ebay for <$200, it works quite well in a ~26x28 kitchen w/vaulted ceiling.  not set up for soundstaging, as this isn't a critical listening enwironment, it fills the room w/tight energized bass.  far better than a rel strata or velodyne (don't remember the model), both of which retailed for at least twice the price.

danberg, unless you can center a sub between the monitors, i'd say forget it, for 2-channel audio.  but, your location choices suggest that you could run a pair, one on either side of the couch.  if this is the case, then go for it!  if ya can only afford one now, get the second one later.

doug s.

[Psychicanimal]

For the record, I did visit Doug last year and heard the setup pictured.  It does have deep, visceral bass.  

Then again, every setup is application specific and subs like the VMPS Larger do not fit the bill with my mini-monitors.  I *consciously* sacrificed the lowermost octave in favor of ensuring seamless integration.  That's why knowledge is necessary.  As long as the choices made are conscious, then there's no problem--you're aware of what you're doing...

The woofers John R. recommends look real good and you could start with one and later build a second one.  You could forgo the passive radiator, depending on the extension of your mains.  Read, read, read!

[doug s.]

...Then again, every setup is application specific and subs like the VMPS Larger do not fit the bill with my mini-monitors.  I *consciously* sacrificed the lowermost octave in favor of ensuring seamless integration.  That's why knowledge is necessary.  As long as the choices made are conscious, then there's no problem--you're aware of what you're doing...

agreed about "application-specific".  room size is key, here.  even brian cheney would recommend a smaller iteration of his subs, if your room size is smaller.  psychic's room size, afaik, was quite small.  (12x14?)  a pair of larger subs in a room that size would be folly, imo.  a pair of smaller vmps subs would certainly energize that room; & i'm sure his nht's worked fine.  as i said, my present yamaha subs, w/their two 8" drivers per sub, have no problem energizing the ~15x22 room where they presently reside.

why i know room size is key:  even tho i have never heard psychic's modwright-tweeked swan m1 mini-monitors, i am sure they would work *perfectly*, w/seamless integration with vmps larger subs - in a room sized as mine was.  why do i say this?  cuz i had in my rig a pair of proac tablette 8 reference signatures - at 10.5"h x 6'w x 9"d, w/4.5" woofers, and 86db efficient, these things *rocked* in that same room, when crossed over to the subs at 70hz...  the sound was fantastic - almost up to the meret re's shown in the pics.  in fact, some folk mite prefer the proac's; it's a matter of taste, imo.  i certainly could have lived with them long-term.

doug s.

[tex-amp]

ACI just redid their website. Excellent FAQ section, audio glossary, and subwoofer primer.

[Psychicanimal]

why i know room size is key: even tho i have never heard psychic's modwright-tweeked swan m1 mini-monitors, i am sure they would work *perfectly*, w/seamless integration with vmps larger subs - in a room sized as mine was. why do i say this? cuz i had in my rig a pair of proac tablette 8 reference signatures - at 10.5"h x 6'w x 9"d, w/4.5" woofers, and 86db efficient, these things *rocked* in that same room, when crossed over to the subs at 70hz... the sound was fantastic - almost up to the meret re's shown in the pics. in fact, some folk mite prefer the proac's; it's a matter of taste, imo. i certainly could have lived with them long-term.
...

I knew *ewe* would say that.  However, seamless integration is more than just being able to slope both ways evenly.  The damping pots are crucial in making the depth and energy of the soundstage match.  The tonality and speed of the woofers/sub cones must match, as well as the amps'.  My setup was truly invisible.   The NHT's go higher--and faster--than the VMPS.  In my setup passive radiators wouldn't do it.  The NHT's have the woofers off center, unlike the VMPS.  That avoids standing waves and unwanted resonances.  It was part of the plan.  I got my two NHT's without a scratch for $300 used, including shipping.  I plan to use some Deflex panels, Marigo Dots and better internal wiring.  If I was going to use bigger subs I would definitely use horns--with isobarics a close second.  I heard Kevin Barrett's (KAB Electroacoustics) all DIY horn system  and the speed and impact of the bass was uncanny.  Taking notes, Danberg?

Oh, BTW, Danny Boy didn't "tweek" my Swans--it was an *overhaul*.  The cost was more than the speakers'...They have a new set of wings. Steve Rothermel (Ridge Street Audio) is extremely impressed with their performance.  He said they're the best cone/ribbon speakers he's ever heard.

[doug s.]

I knew *ewe* would say that.  However, seamless integration is more than just being able to slope both ways evenly.  The damping pots are crucial in making the depth and energy of the soundstage match.  The tonality and speed of the woofers/sub cones must match, as well as the amps'.  My setup was truly invisible.   The NHT's go higher--and faster--than the VMPS.  In my setup passive radiators wouldn't do it.  The NHT's have the woofers off center, unlike the VMPS.  That avoids standing waves and unwanted r ...

psychic, you miss the point.  sure, damping pots are useful - which is why i suggested you get the marchand xm-9 - cuz i had such good results w/*mine*!     and, i am also sure you have good results w/the nht subs.  the nht drivers are one of the most popular (if not *the* most popular) drivers used by the folks on the diy basslist.  and, of course, how could anyone argue w/a built pair for $300?  

however, you dunno what yure talking about re: "speed" of the vmps, and/or how high they go.  1st of all, yer subs are set to 80hz - *every* vmps sub will have no problem doing this - i have had my larger subs crossed as high as 125hz, & the blend was seamless - with swan m1.2's, the slightly larger iteration of your m1's, w/5" woofer instead of 4", & slightly longer ribbon.  your opposition to "passive radiators" is based upon some erroneous adwice given to you from someone you trust; it is *not* based upon experience.  and, vmps' "passive radiators" are unlike any other passives on the market.  they are 90 degrees offset from the other active drivers & are slot-loaded.    and, it isn't having woofer drivers offset that avoids standing waves per-se - it is having *multiple* woofer drivers that does this:  you only need the drivers to have different dimensional relationships w/the room boundaries.  the original & smaller vmps subs will go even higher than the larger, if needed, but why anyone would ever need to cross over higher than 125hz is beyond me.  regardless of brand, size of sub should be based upon room-size considerations, imo, not how high you need to cross them over to your main speakers.  

in my old rig, w/the larger vmps', why would i want "faster"?  the bass sounds REAL.  period.  anything *different* wouldn't be as good.   vmps subs are "fast" enuff to keep up with *any* speaker on the market, electrostatics, ribbons, *ANYTHING*.   how do you think mr cheney incorporates his woofers into his ribbon speakers?  the rm40's & the rm/x's have passive-radiator slot-loaded subwoofers built-in, & crossed over as high as 200hz.

in your rig, if ya had tried a pair of smaller vmps', i am positive the transition between sub & monitor would have been just as seamless.  the *only* difference wooda been a bit lower extension and a bit more palpable bass texture...     'course, we don't know fer sure if ya haven't tried, now do we?    'nuff said...

doug s.

[Psychicanimal]

Douglas,

The offset woofers are to avoid standing waves inside the cabinet.  

All I can say is that horn subs must be *experienced*.   Remember I play very fast music and my ears are trained for that.  The Deflex panels I plan to add to my subs will increase the speed by breaking up the backwave and letting the woofers move back and forth better.  Danny Boy put Deflex inside my Swans and the improvement was stunning.  The Swans you tried are not in the same league as mine.  They are a bad compromise.  The woofer is too big for the ribbon tweeters and will be slower; the cabinet is wider, the front is not leather covered nor beveled and the speakers will not image as well.  Once Steve Rothermel showed me how to properly position them they dissappeared completely.