Modula MTM with Dual 15" Sealed BassBin?

[1Michael]

Hello all. Well after having listened to the big RS 3ways for some time I am still left wanting more bass, so I have decided to stop messing around and use dual 15'' bass bins to get some real kick in the chest action. I am looking at the Dayton Series II, ST385-8 with:
Power handling: 300 watts RMS/425 watts max Voice coil diameter: 2-1/2" * Le: 4.25 mH
Impedance: 8 ohms
Re: 5.8 ohms
Frequency response: 20-1,000 Hz
Magnet weight: 90 oz.
Fs: 19 Hz
SPL: 89.8 dB 1W/1m
Vas: 10.63 cu. ft. or 301L
Qms: 8.30
Qes: 0.33
Qts: 0.32
Xmax: 7.9mm
But I am open to suggestions on other drivers.
I listen to rock, techno and that kind of stuff, no jazz but maybe a little classical in the mix. I tried to model this driver in WinIsd with the parameters according to the well known tutorial...and again, it does not work at all. I will not try that program again, I have tried for 6 years to no avail. I tried Boxplot and if I did it correctly comes out to a box that can be 15'' x 15" x 21".
Could someone that knows what they are doing, unlike me, run this driver and see what box size comes up? I need it 15"x15"x? And it Must be sealed. Thank you all in advance :T

[ThomasW]

The Le of 4.25mH tells us the Dayton Series II isn't really a driver we want to pair up with speakers as good as Modula MTM's ......

If you really what quad 15"s go with the RSS390HF.

I'm going to use RSS265HF's for my NeoDcc bass bins.

A compromise between these would be RSS315HF's..

[1Michael]

Excellent! I did not even think to look at the sub drivers…duh…yeah I will go with 2 RSS390HF’s per bass bin and probably a OAudio plate amp. Isn’t that the one you usually recommend? Would these bins need a Xover? Thanks.

[Xander]

Excellent! I did not even think to look at the sub drivers…duh…yeah I will go with 2 RSS390HF’s per bass bin and probably a OAudio plate amp. Isn’t that the one you usually recommend? Would these bins need a Xover? Thanks.

You will need to highpass the modula MTM, lowpass the bass bin, and possibly high pass the bass bin. This depends on if you have a sub.

How are you running your modula mtms right now?

[1Michael]

I am running the big RS 3ways right now but i'm just gonna add the bass bins to the future modulas.

[Xander]

I am running the big RS 3ways right now but i'm just gonna add the bass bins to the future modulas.

What do you plan on powering the modula/bass bins with?

It will simplify things greatly if you power the modulas with an outboard amp. Then use the pre-outs from your receiver or pre-pro going into an external pro crossover. This crossover will split the signal to the modulas and bass bins. This entire signal will be highpassed at the sub crossover point by the receiver/pre pro, and the sub will take over below the bass bins.

[1Michael]

Actually I was planning on powering the bass bins with an oaudio plate amp so that I can control the bass level better and the modulas being powered by the system amp.

[ThomasW]

For all practical purposes the idea is to build subs and use them as stands. If you want them to play low in really small boxes, you'll probably need more EQ than that provided by the O-Audio amp..

[Ray_D]

Similar approach

My mains are a pair of modified Zaph centers and sitting on a pair of RS315HFs powered by a pro amp. There is enough bass for me.

[1Michael]

I wont be using them as subs since I have a RLP-15 Sonosub and a RLP-18 sealed sub so these would be only for the upper/mid bass duty, to add to the 60-120Hz area, or they could go higher. Thomas what are the frequencies and dimensions your bins will be set to?
PS I cut the subs off at between 50-70Hz depending on the source. So the bins would be for above this area.

[---k---]

When you say that you are running the big rs 3ways, are you referring to CJD's design w/ dual RS270s? Wow, that would be impressive if you thought those didn't have the bass you're looking for. Maybe it is just that they have the drier bass and reducing the box size with some solid fill to raise the Q would get. Wouldn't hurt to try.

[Xander]

I still don't get how you are planning on high passing the modulas. The plate amp does not high pass the modulas, it only low passes the bass bins. The modulas and bass bins will be playing the same frequencies and you won't be taking the stress off of the modulas.

[1Michael]

It is just that dual 10's are not doing the deal for me. They sound good and accurately reproduce music… but I need some more upper or mid bass, hence the dual 15’s.
I was not planning on high passing the Modulas, I was going to run them full range and add the bins for some synthetic punch. Is this feasible? Maybe I misunderstood what Thomas said he was going to do with the neo’s?
Do I need to high pass the Modulas? If so then it would be in that 50-70Hz range. What are my options?
-K- I am not able to add anything in the RS3ways because they are sealed. My wood skills are not good enough yet to add access panels lol.

[chasw98]

Here is what I have been doing and it is working quite well. This picture is from the beginning when I was just building the system.



I am using a 2 way system on top for mid and tweet that is passively crossed over. The bass bins are using a pair of RSS315H's on each side and are actively crossed over by a modified Marchand crossover set at 312 Hz for the crossover point. My IB subwoofer is crossed at 40 Hz. These reproduce bass very nicely and cleanly in my room. For you to take advantage of bass bins under a MTM or MT speaker you really should get an active 2 way crossover (fairly good and reasonably priced for around $100.00) and then let your pre pro cross to your sub woofer.

Chuck

[1Michael]

So your bins are running from 40-312Hz? Do I need to cut off the Modulas at whatever the upper frequency the bins are running or can I just run them full range and have the bins overlap?

[chasw98]

So your bins are running from 40-312Hz? Do I need to cut off the Modulas at whatever the upper frequency the bins are running or can I just run them full range and have the bins overlap?

It would be better to cut the Modulas off at the lower frequency so that you cross out of the bass bins at 312 and cross into the modulas at 312. That is but one example that is possible. It is possible to cross out of the bass bins at 312 Hz using a Linkwtz-Riley (LR) 24 and cross into the modulas using a Butterworth 3rd order at 250 Hz. With the modern electronic/active crossovers of today you can try all sorts of combinations and measure/listen to hear what works best for you in your environment. Most people are very happy crossing a bass bin in the 200 to 400 Hz range using a LR12 or LR24 slope. With your basic Behringer CX2310 this is easily done and will work very well in most cases.

BTW, here is a picture of the finished bins and uppers.



Chuck

[---k---]

I was thinking that if you pulled the driver out, you could throw a couple of 2x4s or bricks in there to take up volume (probably more than a couple) and see how it sounds. You would loose a little bit of the extension, but should gain some punch.

They very dry bass of a critically damped box is different and not what most people are used to. I think it really excels with classical music like CJD listens to, and may leave those who listen to rock and club music looking for more boom. I know I've struggled to come to grips with whether I like the bass in the Khans or not. I sometimes fine it lacking, but other times it is very good. Depends highly on the CD.

If reducing the box volume doesn't suite you, then I think you're on the right path with active bass bins. A digital crossover would allow you to boost up the bass to your liking.

[1Michael]

The active Xover does sound like the way for me to go. I have always held a certain belief that I should have 2 separate speaker systems. Of course I live in the real world so that is not an option. One for the classical type music and one for My techno/rock/whatever stuff. I to date have not heard a speaker system that does both well. My first real speakers were the Altec Lansing voice of the theater units, they were actually the studio monitors because the drivers were enclosed in a single box. At the time they slammed pretty good but when I would kick on classical...Bleghk! They sucked. Totally unrealistic sound. I believe my friend has behringer unit I can have so I can experiment with the xover points and such. Thank you all for the great help! ;x(

[Ray_D]

Buggers

Read this: http://sound.westhost.com/bi-amp.htm

[1Michael]

Can you explain what he is talking about in laiman's tems 8O
I am thinking more amps means more money than I might have available.

[ThomasW]

In most instances bi-amping with active electronics sounds better than passive crossovers.

You'll need an active (electronic) crossover and a separate stereo power amp to add bass bins to your Modulas.

And this will only work if your receiver has separate pre-amp outputs for the front/main channels.

[chasw98]

Can you explain what he is talking about in laiman's tems 8O
I am thinking more amps means more money than I might have available.

What you are doing when you actively bi amplifiy a speaker system is this:
01) Take a full range signal 20 to 20 Khz and put it in an electronic crossover.

02) The electronic crossover splits the signal into Low (20 Hz to 312 Hz) and Hi (312 Hz to 20 Khz).

03) The low signal would go to one channel of amplifier A and the high signal would go to one channel of amplifier B.

Obviously if you are going to do this for a stereo 2 channel system, then you would need 2 amplifiers, one for left and right low signal, and one for left and right high signal. The cost is not as bad as you think. You could buy a Behringer CX2310 crossover ($50 at audiolines.com) and a Behringer A500 amplifier ($150 at audiolines.com) for around $200.00 total. Check out audiolines.com. I am assuming that you already have an existing stereo amplifier.

[1Michael]

So the Modulas would have no Xover inside the box? And this would sound better than the existing xover? Ok based on your recommendations I shall go this route :T
I have 2 Adcom 555's I am using now and plan on getting the Emotiva xpa-5 in the future. As much as I would love to get some Ayre's those will have to wait until I become a brain surgeon or something

PS My preamp is the Outlaw 990 which will have to be replaced because as I understand it the thing cannot handle the new fancy shmancy codecs.

[Brian Bunge]

No, the Modula would still be passive, in and of itself. The electronic crossover would be between the drivers in the bass bin and the 7" woofers in the Modulas.

[1Michael]

Ah I see, well it still looks doable.

[Dean100]

I have done something almost exactly as Chuck is doing and has described above.

Running two of the Aura NS10 -513 sealed in each bass bin with an approx. Qtc of .58 These are presently on clearance at Madisound.

On top of these are my Nat P's which are sealed.

Also I am running a sealed 15" Tumult subwoofer.

How I have these hooked up are as follows. B&K receiver pre outs to a Behringer CX2310 crossover. From the CX2310 - EP2500 - Bass Bins. From the CX2310 - B&K Amp - Nat P's. From my B&K receiver subout - Hypex plate amp on sub.

I have the sub crossover set on my receiver to 70hz. I am high passing the Nat P's at 230hz. The bass bins roll off at about 70hz to match the sub.

These were just completed so I am still doing some tweaking and adjusting. What I have found so far, is that the Nat p's sound has improved considerably. The entire system will play a lot louder. I am hearing details in the music that I was not hearing before. I don't need the sub on some music.

With the active crossover, you have a lot of room for adjustment. You can up the level of your bass bins to add more impact or slam if that is what you are looking for.

[AlanH]

woofer vs subwoofer in a bass bin

Hi All,

I've been thinking about adding bass bins to my HT setup and this thread started me thinking about the benefits of using subwoofers vs woofers.

My current mains are Zaph's old Vifa XG18/Seas 27TDFC MTMs , which have a nice midrange but pretty mediocre bass. I'm also using an Exodus Tempest-X in a sealed box to hold down the low-low end (someday replaced with an IB, I hope). I figured that bins covering the 50-300Hz range might clean everything up.

So I was thinking to build a pair of sealed bass bin 'stands' for the MTMs, with each bin having two Dayton RS270 10" woofers. These woofers have been tested and appear to perform as well as the more expensive Seas L26 but at half the price. The bins would be biamped with the mains via a Behringer active crossover while the exchange to the sub would be handled by my HT processor.

So my question is should I be planning to use the RSS265HF instead? Obviously there's a lot more x-max in the sub driver, which means it would move more air, but I guess I always figured that a driver labelled as a "sub" wasn't meant to handle frequencies in the 100-500Hz range. But it seems like everyone is recommending that as the way to go.

What do you guys see as the pluses and minuses of woofers vs subwoofers in bass bins (provided a sub will be used for the very low end)?

Thanks!

[JonMarsh]

A lot depends on the driver design- ones like the RS265HF, or the Aurasound NS10-513-4A, use techniques to have relatively low inductance voice coils, (which lowers midrange distortion) and relatively stiff cones with a high breakup frequency. That's a lot different breed of "subwoofer" than many other designs with high inductance VC and composite paper cones with relatively low breakup frequencies.

Here's a plot of the RS315HF Frequency response (measured nearfield dipole) It's first breakup mode is higher in frequency than the RS270.





And 2nd Order Harmonic distortion



Plus 3rd order Harmonic distortion



This was at a "nominal" level of 90 dB@ 1 meter. Many/most 12" woofers will have a tough time matching that performance.

At 100 dB, distortion rises, of course.





It's pretty close to state of the art for a 12" driver, and at a reasonable price from PE. The large amount of copper in the gap keeps voice coil inductance modulation down, and keeps the rise in distortion with increasing frequency fairly well controlled.



Closer to state of the Art is the Aura NS12-513-4A, with a long throw underhung voice coil assembly in a copper lined VC gap.

SPL


HD2 @ 90 dB



HD3 @ 90 dB



Note, as one would expect with increasing frequency and decreasing cone motion, the distortion keeps dropping all the way up to 1 kHz! Sadly, that's not very common place!

Contrast that performance with an Oaudio TC2, a fine metal cone subwoofer from a few years ago, which is still much better than many sub drivers on the top end.

HD2 @ 90 dB




HD3 @ 90 dB




This is why I'm using dual NS10-513A in the low section of my project in progress. Midrange and tweeter still to be determined.

[AlanH]

A lot depends on the driver design- ones like the RS265HF, or the Aurasound NS10-513-4A, use techniques to have relatively low inductance voice coils, (which lowers midrange distortion) and relatively stiff cones with a high breakup frequency. That's a lot different breed of "subwoofer" than many other designs with high inductance VC and composite paper cones with relatively low breakup frequencies.

Hi Jon,

Thanks for the info...I guess one of these advanced sub drivers is the way to go. I did some fiddling in UniBox. It looks like I could fit two RSS265HF drivers in a remarkably small, closed box (<50 liters). Even better, in said box I'd be able to dump a ton of power into them and still not exceed x(max). This is probably a good thing because my HT room is relatively large (>3500 cu ft), though on the other hand we don't sit that far away from the action.

Thanks again!

[chasw98]

The bass bins I built are based on the RSS315HF 12 inch drivers and 2 each are stuffed into two 4 cubic foot cabinets. For a long time, I believed they were not that good a driver (no matter what jonmarsh said!). Silly me, when you put on a piece of music with 40 to 300 Hz information, the drivers will speak to you just fine. While searching for a better driver, I tried some AE TD15X 15 inch drivers, and some other 12 inch drivers, but in the end, the Dayton 12 inch was the best of all. I was almost ready to buy a pair of the Aura 10 inch drivers to try (cheap at Madisound right now) but in a side by side comparison on paper, the Daytons still were better. Just my .02.

Chuck

[exojam]

So Chuck, what are you going to be doing with those AE's?

[chasw98]

So Chuck, what are you going to be doing with those AE's?

I am playing with these right now, but am going to also throw some waveguides into the mix for fun.

[exojam]

;x( ;x( ;x(