Bass Bins & crossovers

[Timbo]

Hi folks,

I did a search but did not find a answer to this question:

If one was to add "Bass Bins" + bi-amp with an active external crossover to releive a MTM of it's lower Midrange, say 60-300Hz, do the bins need additional crossover componets in them, or is it straight wire from preamp > external x-o > amp > bins?

Thinking of Modula MTM's w/ RS225's or 270's as bins. LFE is handled seperatly.

I'm sorry, does that question make sense?

[ThomasW]

Your wiring example is correct.

Usually people use 10" or 12" drivers in bass bins.

[crackyflipside]

Check Kingpin's "Dont spit at the n00b" build thread. He built some monster bass bins for his monster speakers.

[kingpin]

Here is the way mine are hooked up.

Image not available

What I do which I don't know if it's right or not is change the crossover setting depending on what kind of music I listen to and if it's for ht or not.
No internal crossover for the bass bins.

[DeanP]

Is it possible to make a passive crossover to make bass bins?
I have mtm's and would like a bit more bass, I have dual shivas x-overed @80 thru my reciever, but I would like something to augment between say 250-80.
I have my pre/pro going to an amp to drive my six speakers. It would seem to me to make a "low range" x-over for "x" driver and use my pre/pro's main outputs to drive them. I could make a 12db/octave type...
The active type seems the way to go but it would be less expensive right now.
Am I totally wrong or could this work?

[kingpin]

Is it possible to make a passive crossover to make bass bins?
I have mtm's and would like a bit more bass, I have dual shivas x-overed @80 thru my reciever, but I would like something to augment between say 250-80.
I have my pre/pro going to an amp to drive my six speakers. It would seem to me to make a "low range" x-over for "x" driver and use my pre/pro's main outputs to drive them. I could make a 12db/octave type...
The active type seems the way to go but it would be less expensive right now.
Am I totally wrong or could this work?

If I remember correctly I posed the same type of question early in my speaker build. The response was that the cost of building a crossover would be close to buying the active crossover. Then there is the question of having the abilty to do measurements so you can make a proper crossover.
The cx2310 active x-over seems to be priced right around the $135cdn mark.

Mike

[joecarrow]

The problem is that for a low frequency crossover, the inductors and capacitors become very large (read: expensive).

If you can measure and simulate well enough, and can design a passive crossover, there are some toroidal core inductors that will give you really large inductance values with low DC resistance and low-ish cost. You can also by large numbers of low-cost (the GE surplus at Madisound are a favorite), and parallel them together to get the required values. This has the added benefit of lowered ESR.

Overall, I'd say I'm a big promoter of active crossovers for anything below 500 hz.

[DeanP]

The cx2310 active x-over seems to be priced right around the $135cdn mark.

Yes,a simple cap & inductor might meet this price but then I would have to build another two channel amp...I guess if I made bass bins there would be no need for parts(x-over) if I get a cx2310. Thanks for the help.

[cjd]

Couple notes here.

If you're going active, go with SUB drivers that are clean up higher into the frequency range. RS10 HF subs got serious consideration when I was building the WWMTM but they don't work well passive due to the sensitivity difference. Same size box as I used ported 10 17Hz would have worked. The RS270's have BIG volume desires.

The other thing is to understand that adding a passive crossover for a bass-bin means you also can't use your current crossover. That was the real kicker for Kingpin, it would have been a whole new project, not just an add-on tweak.

You can look at the WWMTM thread to get an understanding of what a passive crossover for your project might resemble. You could just build bigger boxes for your Mods and built the WWMTM's too.

If Ryan reads this he'll get another view on an answer to the question he asked me the other day.

C

[DeanP]

Hmmm...Would I have to revise my mtm's x-over even if it isn't in the same feed line? This is how I would picture the set-up if I went passive...
pre/pro mains output->amp->mtms
pre/pro mains speaker output->bass bins
pre/pro lfe output->sub amp->sub

Would this lend to mtm's x-over change still?

[cjd]

Unless you don't roll off the bottom of the MTM's any, yes.

[DeanP]

The way I picture it, it would be like having four mains but one set would be missing the top end...

[ThomasW]

Using passive crossovers for bass bins IMO isn't a good idea. The large inductors in the signal path trash the amp's damping factor. And 'good' inductors for this purpose are virtually as expensive as one of the Behringer crossovers.

[DeanP]

Gotcha! I guess I'll wait and do it properly!
Thanks! :T

[---k---]

I read everything, understand little.

[Timbo]

So re-thinking my driver needs for a bass bin, preferences for 2 of the dayton 265 HO vs. 1 Aurasound NS-12. My amp can do 280 a side into 8 Ohms , 450 a side into 4 Ohms. If I went for the 2 4 Ohm drivers should I try to wire them so the amp sees a 4 Ohm load...Is this perferable?

I am hoping to send 300Hz down to the bins, and try to go as low as I can go.....

Any other options for drivers?

Tim

[ThomasW]

The 2-265's would probably win the Vd battle (I haven't done the math). That said the NS-12 is one of the lowest distortion 12" drivers Jon's measured.

There's no need for either of those power levels with normal home use, so it doesn't matter if you have 4 or 8 ohm loads.

[BigJim_inFLA]

Any other options for drivers?

I'm using two RSS315-HF 12" per side as bass bins for my Nat P's. Wired in series for an 8 ohm load driven with 125w per channel. I cross to them at 220 Hz and run them down to 60 Hz, they sound very nice. They like a rather large box. I think the HO version can be used in a smaller enclosure. How big did you want to go?

Jim

[Timbo]

I hope to keep them around 3 cu. ft.

[cjd]

I cross the RS270's in that range! :P

[Timbo]

Chris,
I thought the Rs270 cabinet needs wre much higher. 2-270's in a 3.0 cube box?

[JonMarsh]

It really depends on what you want to do with it- a single RS270 in an optimized reflex is not small- we're talking 75-80 liters here. Sealed may make more sense, with two, but it depends on whether extension or SPL is your first priority.

[cjd]

A single RS270 sealed, a single RS315HF sealed, or a single RS265HF ported to 17Hz all take about the same box volume.

C