Stereo subwoofers

[Jussi]

Hi!

Have anybody tried stereosubwoofers? And if, can they be used with higher cross than normal mono?

I've runned a bit of a corner with my project and would need a solid bass solution below 120-150Hz but is that too high considering simple and conventional, well placed monopole subs/woofers in stereo? In separated boxes than mains naturally so positions can be fixed and DSP handles delays into order.

Thanks!

Jussi

[bickeler]

I'm sure many here in the forums do I would think?
I have prefered stereo subs for about 8 years and have not really used a single since.

One is output two is always better than one.


Two in regards to your second question with the big drivers I'v used (12-15")I generally wouldn't go above 250 and thats pushing it pretty far.But to me it still sounds better than a mono sub as far as integration goes.


Three it just looks cool.

[Jussi]

Originally posted by bickeler

Two in regards to your second question with the big drivers I'v used (12-15")I generally wouldn't go above 250 and thats pushing it pretty far.But to me it still sounds better than a mono sub as far as integration goes.

Above 250Hz? What kind of crosses have you used them? And placement, just along mains or something different?

Jussi

[sreten]

Hi,

Stereo subs (even if actually mono, i.e. both output the same)
if they are carefully placed do produce smoother in-room bass.

It is also true if they are true stereo the c/o frequency can be
somewhat higher, but this is very placement dependant. E.g.
if the subs are the speaker stands then you have a 3-way
speaker, and no real constraint on the c/o frequency.

/sreten.

[bickeler]

Yea I've always used subs as in placement with mains.This avoids many crossover issues that many complain about.

It also let's you even use a passive crossover(Although not greatly recommended)it's not so bad buying big inductors and caps for 200-300hz but say 80hz ouch that is expensive.

But there are many subs that don't even sound good at 250hz so one has to be careful in that range with driver selection.


For the record I am using passive 3rd order for my dipole subs right now.But I am going to be using a mono sub for LF below (The dipoles need the augmentation I think)80hz that will use an active crossover via plate amp.

[phreeky82]

i have my three way mains bi-amped with the lower frequency just the 8"s alone, and have at times put the upper frequencies on 100Hz and up and the lower on a sub-amp.

at other times i just bi-amp with the upper at 100Hz up and the lower running at full range with the lack of highs they produce meaning it's not too bad (of course it depends what sound you're after, the extra strong mids from this i find great for movies & tv but not my pick for music and true reproduction).

at present i have them bi-amped and crossed over at 120Hz. my 12" and plate amp have been tossed aside from this setup for now and put with my bookshelves on the computer, not to mention it's not of much use whilst living in a town house :-(

[paulspencer]

I'd be wary of crossing too high if you are talking about typical home subwoofers. Often 80 Hz is too high.

I cross mine around 50 Hz and I currently have them together on one side in the corner. There is no significant audible difference to placing them on either side as dual mono. I have trialed the corner position for the last few weeks to see if it would work. There is no harm done to imaging compared to dual mono placement. I find the information that moves upper bass across the sound stage is higher than this. I find I can still locate double bass on the stage and this is surprising when quite a lot still comes through the subs.

I have crossed at 80 Hz with a 4LR analogue active xo and didn't like the result - the subs degrade the sound up that high quite noticeably compared to the vifa P17 TL loaded drivers in my mains.

To cross at 80 - 120 Hz I'd say you need some VERY good sub drivers, and higher than that ....... then I'd say perhaps you are looking at woofers and not subs. I could be wrong but it sounds like too much of a stretch to me.

[Jussi]

Originally posted by paulspencer
To cross at 80 - 120 Hz I'd say you need some VERY good sub drivers, and higher than that ....... then I'd say perhaps you are looking at woofers and not subs. I could be wrong but it sounds like too much of a stretch to me.

Well there are some aspects with this. Some or even many average priced commercial subwoofers don't even support high crosses. Crossover isn't steep enough (12dB/oct) and response shape changes while cross is lifted higher. For example some REL Acoustics models have very good 16Hz F6 extension when crossover is set to it's minimum. At maximum xover F6 can be around 30-40Hz. This is one thing need to be in order, response shape. And while subs would play larger band than normally, better adjustment possibilities wouldn't hurt. EQ, careful placement, acoustic treatment, bass traps...

Another thing is the driver itself. I know I can't and I even wouldn't use new very heavy mms, relatively small cone sub that just moves alot. I'd prefer larger drivers with less excursion. For example PA drivers have very good response, 200-500Hz no problem, distorsion is low, drivers can handle brutal hammering since coils handle a lot of power and they are also protected from overexcursion with very progressive suspension.

So the subs themselves are one issue. But if they are in order I don't see that much disadvantages that I wouldn't try this.

Actually the drivers I have in mind are way over my SPL/dynamics/distorsion etc need but they also work in dipole if my stereomonopole setup just don't work and I need a change in plan. Single 10-12" driver in dipole wouldn't be that good then...

So, a 18" PA woofer on both channels in closed cabinet running to 120Hz or so? Boom!

Jussi

[paulspencer]

When you said subwoofer I was thinking of a typical home audio sub driver. An 18" PA driver is another thing entirely. Active woofer might be a better term. I see no problem at all in that case.

You would want to consider distance to the mains and crossover frequency, that they are not too far away.

One question is will this meet your requirements in terms of extension and SPL?

I also question whether or not you may be better with a vented alignment in this case.

Yes as you mentioned the upper xo point will affect the F3. You can get the F3 lower just by crossing over lower, a cheat way of getting a better F3 spec on paper and giving the impression of better low end response.

[tinitus]

Hi Jussi, I remember we dicussed BMS driver, but now I am more interested in Alliance 18"....and they promisse good extended frequency.....wonder which way the mean
I would also like to see plateamps with much higher crossover points
Allthough not excactly cheap, it could be interesting with four Adire Exstremis 6.8 pr side
Its sometimes od to experience how good perception of bass depends on phase relation between midrange and tweeter