Subs as woofers

[kgveteran]

Can I use a subwoofer driver in a fourway as the bass driver ? The configuration would be (2)12's(1)8"(1)4"(1)Tweeter.

The woofer would run from 20hz-400hz
The 8" would run from 400-800
The 4" (mid) from 800-2K
The tweeter on up

The Dayton 12" goes up to 1k, i would think 800hz would be fine.

[joecarrow]

There's some measurement data on those drivers here: http://mfk-projects.com/rs_12_hi-fi.htm

Your plan sounds good, but depending on the low frequency excursion you might run out of SPL before requiring a 4-way. You could probably cross the 12"s high enough to just set a Modula MTM on top of a bass bin and call it a day.

[SteveCallas]

The 4" (mid) from 800-2K

That seems to be a pretty small range for a dedicated mid, no?

Kinda like joe mentioned, what about an MTM that goes down to ~200hz and then let the woofers take over from there? The current MTM is intended to be crossed over to a sub at 80hz, so 200hz would make their life that much easier. If you want to really get to 20hz, I'd use two HiFi15s, they have an extremely low Le, so 200hz shouldn't be any problem. But you'd get into tweeter height issues with dual 15s though, so it would have to be a WMTMW. This is a design I've been thinking about myself....a true full range.

[dlneubec]

I'm currently crossing my NaO MIni open baffle MTM's over to a stereo pair of sealed 12" subs at about 120hz that work as bass bins. It seems to work great. YMMV.

Dan

[Dennis H]

The woofer would run from 20hz-400hz
The 8" would run from 400-800
The 4" (mid) from 800-2K
The tweeter on up

The crossover would be a real bear on the 8" and the 4". The highpass and lowpass filters (on the same driver) interact with each other and can give you problems if they are too close to the same frequency. Ideally, you'd like a driver to cover at least 3 octaves to keep things simple although you can get by with 2 octaves. Your 1 octave on the 8" and 1.3 octaves on the 4" is really pushing things.

[Paul W]

Many subwoofer drivers get ugly by 400Hz...so I'd be very careful in selection and then get them out of the mix as early as practical. With a reasonable xo order and sane SPL, a good 8" will handle 200Hz fairly easily.

[Marzen]

The crossover would be a real bear on the 8" and the 4". The highpass and lowpass filters (on the same driver) interact with each other and can give you problems if they are too close to the same frequency. Ideally, you'd like a driver to cover at least 3 octaves to keep things simple although you can get by with 2 octaves. Your 1 octave on the 8" and 1.3 octaves on the 4" is really pushing things.

Ditto on that. I have a 4way that proved to be a real pain due to the above. My impedance is about 2 ohms nominal and system phase is pretty wacky thru both band pass filters. I ran it thru a digital filter with 4 amps 'cause I couldn't get it to the point where I felt comfortable buying actual xo parts. I'll get back to it at some point in the future I suppose.
RSS315HF 300
RS180S 300-800
RS52 900-3500
RS28 4000
Good luck if you take that on - I'd be personally interested in how to get around the inherent problems for my own project.
Ward

[kingpin]

Many subwoofer drivers get ugly by 400Hz...so I'd be very careful in selection and then get them out of the mix as early as practical. With a reasonable xo order and sane SPL, a good 8" will handle 200Hz fairly easily.

Paul.

You have built some beautiful speakers there. Especially the 4-way test mules. I am building something similar.

http://www.htguide.com/forum/showthread.php4?t=20872

Mike

P.S. I just took another look at you site. Okay, maybe similar is not the word. More like totally different but still large. :lol:

[joecarrow]

I was going to check the numbers earlier today, but I was at work. If you use 200 cm Sd and 6 mm Xmax, you get above 110db down to 140 hz. A pair of RS HiFi 15"s will barely get you to 110 db at 20 hz sealed, counting room gain. You could easily cross from the RS hifi subs to a 7" woofer. You would have less thermal compression in the woofer and less stress on the tweeter if you go MTM with 5" woofers.

Maybe something like CJD's MTM (here: http://www.eldamar.net/audio/rs150mtm/) could give you some high SPL with an active crossover to a bass bin.

[SteveCallas]

Heck, who's talking sealed? :B I can easily extract 110db+ levels out of two of those without coming close to exceeding excursion and with very little power. Won't be the smallest speaker in the world, but hey, if that's what it takes, that's what it takes.

[kgveteran]

I was going to check the numbers earlier today, but I was at work. If you use 200 cm Sd and 6 mm Xmax, you get above 110db down to 140 hz. A pair of RS HiFi 15"s will barely get you to 110 db at 20 hz sealed, counting room gain. You could easily cross from the RS hifi subs to a 7" woofer. You would have less thermal compression in the woofer and less stress on the tweeter if you go MTM with 5" woofers.

Maybe something like CJD's MTM (here: http://www.eldamar.net/audio/rs150mtm/) could give you some high SPL with an active crossover to a bass bin.

I built this center for my cabinet guy and never thought of getting the bass out of the way and seeing what it can do from 200hz up.Looks interesting.

As always..Thanx

[cjd]

Yeah, anywhere from 150Hz to ~250Hz would be a great spot to cross to 12 or 15" RS subs with the MTM (lower for bigger...). It's one of the possible solutions under consideration for my HT, actually, except that I'd go 8 or 10" since I have an IB. . . And, it's designed to be an any-which-way speaker (i.e. center or main, horizontal or vertical). Some small compromises because of this, but what design doesn't have lots of compromises.

C

[kgveteran]

What would that design sound like in a vertical array flanked by a RS 10" on either side all in one cabinet.It would be a huge cabinet, but it's kind of cool thought.Now take a plate amp with an L/T circuit and seal the 10's. I could power the MTM with an outboard amp and the plate amp would cover the dual 10's.My thought would be to really get down into the 40hz or 30hz with some real spl's.I've always wondered what quasi-full range monitors would sound like.....just throwing idea's around.

Or a couple of 12's sealed :B With my bad back I would need to hire some moving guys to shlep it around

[cjd]

Well, it wouldn't work as-is since that would completely change baffle step. Though if you put it near-wall, using one of the no/minimal baffle step versions may do fine.



C

[Mark Seaton]

What would that design sound like in a vertical array flanked by a RS 10" on either side all in one cabinet.It would be a huge cabinet, but it's kind of cool thought.Now take a plate amp with an L/T circuit and seal the 10's. I could power the MTM with an outboard amp and the plate amp would cover the dual 10's.My thought would be to really get down into the 40hz or 30hz with some real spl's.I've always wondered what quasi-full range monitors would sound like.....just throwing idea's around.

Or a couple of 12's sealed :B With my bad back I would need to hire some moving guys to shlep it around

Hi kg,

12s for midbass is a lot of fun.

You might have caught the picture of my new full range design I just put in Art Sonneborn's system, but most certainly you can use "subwoofers" for midbass. Not all of them work well, and you probably want to use something different than most outrageous driver out there, but the unfortunate truth is that few are making drivers with significant Xmax to provide the strong, uncompressed midbass that makes our huge subwoofers sound so much better in movie and music use.

You do want to pay particular attention to the upper range of the driver and the inductance. There's also the question of if you need or even want extension below say 50Hz. Personally I don't for anything used in a home theater, and I'd much rather choose a driver that provides higher overall sensitivity above this range. There are of course many plans of attack and priorities, and therefore many valid choices.

Go ahead and model up the drivers just as you would any subwoofer and look at the excursion requirements for different output levels and frequencies. Keep things "in the green" and you're half way there. The other half being a combination/interaction of crossover and overall directivity and power response.

[cjd]

There's also the question of if you need or even want extension below say 50Hz.

I assume you're saying this with the thought that said speakers would be used with a sub to provide <50Hz?

[Mark Seaton]

Correct. What's a system without some powerful subwoofers? :twisted:

If someone is willing to spend the time to integrate them well, I'd still rather do a separate sub for any system, but the concept of a full range speaker, especially for music, is a long held tradition/preference with its strengths and weaknesses. Whatever the goal, design to it, but my point was to be sure you aren't needlessly chasing it...

[kgveteran]

Hey Mark,
Where's the pics of your new monitors ? I was just throwing idea's around.Not much need for anything below 50hz as you stated.

I would like to see a RS center with dual RS 10" drivers in a smallish cabinet.

My problem now is to power my mains.So many amps.I wish I could get a hold of someone who uses the Behringer 500a's.To bridge three in mono for my mains would do fine.Or run em' in stereo if that would do better in 4ohm. After our long conversations through threads and posts, strong subs fall short if the mains and centers can't cut it from 100hz to 300hz or so.

[cjd]

I would like to see a RS center with dual RS 10" drivers in a smallish cabinet.

Smallish cabinet is the trouble.

If you're talking the RS Subs, it would pretty much require active crossing padding down the rest or you have impedance issues. They'll do smaller cabinet better than RS270's... I've looked at a center to "match" the RS 3-way towers tho.

C

[Mark Seaton]

Hey Mark,
Where's the pics of your new monitors ? I was just throwing idea's around.Not much need for anything below 50hz as you stated.

Here's a link to the thread about Art's meet where he posted two pics of the speakers while we were installing them. They consist of a pair of sealed 12s above and below a SEAS coax that is internally bi-amped (1kWx2@4) with a passive XO for the SEAS and DSP in front of the amplifiers to handle EQ and woofer-mid crossover. The physical config would be very easy for a DIYer to execute. I did spend a lot of time figuring out what I wanted the crossovers to do, looking at a lot more than just on-axis response. :roll:

http://www.avsforum.com/avs-vb/showthread.php?p=8024297&&#post8024297

I would like to see a RS center with dual RS 10" drivers in a smallish cabinet.

I have a pair of the RS270s here as one of the options I was going to look at for a somewhat smaller, fully shielded, powered LCR. I believe I have a more efficient option that actually costs less, so we'll see if I get around to playing with the RS270s. I know some would say they need a really big box, but big is of course relative. Once you factor in the crossover and baffle step interactions, I personally don't feel the absolute Q of the drivers is of much concern. I'm looking at sensitivity, output and excursion requirements while still providing a desireable frequency response.

My problem now is to power my mains.So many amps.I wish I could get a hold of someone who uses the Behringer 500a's.To bridge three in mono for my mains would do fine.Or run em' in stereo if that would do better in 4ohm. After our long conversations through threads and posts, strong subs fall short if the mains and centers can't cut it from 100hz to 300hz or so.

As is almost always the case, if you can afford the size, efficiency is cheaper than power. I'd be hesitant about running those Behringers bridged to a 4 Ohm load, but they are inexpensive. Be sure to also keep an eye on Outlaw & AV123 for some good deals on decent power. If you can find a used CinePro that would be great, but probably a bit too pricy. I forget, what are you are currently using for power to your LCRs?

[kgveteran]

Right now I use three B&K ST140's (105wpc) for the six channels.

I'm looking into a project for the winter.Ashly use to make a Fet-200.It was bridgeable to 385watts mono.I got a hold of one of the tech guys here in town and he assured me the Ashly will power that speaker with no problem @ 4 ohms.

They can be found here in town for about 200.00 each.They look like hell on the outside because of the road abuse.I'll be tearing each one down and make mono chassis's.Should be cool.They have balanced inputs and outputs so I can finally use balanced out on my processor.The Ashly PEQ'a are baanced also.

Time will tell.

[chasw98]

kg:
Look into a used Earthquake 3 channnel. You can find them for less than a $1000 now. They will give you 300 watts X 3 into 8 ohms and more into 4 ohms. Very clean for mains and surrounds. But, they are big! I bought one and it sounds much, much better than the EP2500 i was using for mains and center.

Chuck

[Mark Seaton]

kg,

I'd echo Chuck's suggestion. I'd be a little leary of the old Ashly amps for main speaker use. You're also now bringing even more fans into the room. You will benefit from more amplifier headroom. Figure you're looking for 300-600W into 4 Ohms to make a notable difference.

Keep and eye out for some older amps for a good price, or maybe some more modern pro amps that are more widely known/used. Remember that when you talk to someone at Ashly, their definition of being able to drive a load means it won't shut down, fail, or catch fire. Signal to noise can be an issue with some pro amps in home use. This isn't too big a problem with most subwoofers, but can be with main speakers. Choose carefully.