How to wire xcrover in 310/6 cab

[GustavFL]

Hi fellas,

I'm building a 310/6 cab with 3 Eminence BP102 and 1 Eminence Alpha6-CBMR. The enclosure has 180 L and it's tuned to 38,3 Hz.

I started the idea of building a cab by my myself some months ago, since then I've been studying about it and yet I feel sometimes I know nothing.

I'm using WinISD to simulate drivers' behavior. Unfortunately I don't know how to simulate the closed back midranger.

So, I'm open to suggestions:

-Filters:

Highpass the woofers 2nd order at 32 Hz to protect them.
Lowpass the woofers 2nd order at 1 kHz
Highpass the alpha 3rd order at 400 Hz

Is this highpass enough to protect the alpha from lower excursion?
Here are some graphs as reference:

These data considers both low and highpass filters for BP's and Signal of 350W, which is amplifier's max output at 8 ohms and a good maximum power to consider for this 600W peak power cab.

Xmax is 6.2 although Xlim is 10, as you can see excursion is lower than Xlim but exceeds Xmax (@350W), is that ok?

Is there a limit to air velocity through the port?

The cab will be wired in series-parallel to get 8 ohms load from all four 8 ohms drivers.

How should I wire the filters in the circuit considering drivers configuration and which impedance should each of them handle?

 

[CL400Peavey]

I recommend you look at the non closed back version of that driver and build an internal enclosure for it. It's a more robust driver.

 

[GustavFL]

I see, well, I already have the drivers, so I'm gonna have to do the best with them. This alpha has a really nice SPL response, as I was told one can handle until 4 BP's I think it will be a nice set.

Any opinion on the other matters?

 

[will33]

You don't just wire them all together like that when using a crossover....that's going to end badly.

Think of it as 2 separate speaker systems that just happen to be all mounted in 1 box.

On the low side, you have three 8ohm woofers. Your impedance options there are 2.67ohms all in parallel or 24ohms all in series while keeping equal power distribution amongst all the woofers. Neither of those make much sense.

The la6cbmr has an fs close to 500hz. Rule of thumb there would be to pass at 1khz, though you could get away with 800 using a 3rd order filter.


Easiest solution would be to add a 4th bp102. Then you could have a nominal 8ohm cab on both sides of the crossover. Eminences 800hz 2-way would get you up and running and sound alright while you hone your skills and work up a more purpose built, high power handling crossover. Four bp102's can take a lot of power and the off-the-shelf crossover would be the weak link in the system.


As for the HPF down low, a passive filter that could do that would consist of an incredibly costly array of parts and doesn't make much sense either. I've never had a problem blowing woofers with no HPF but if it is a concern, TB'er fdeck's unit is the answer there. It does it actively before the cab, is adjustable and is very modestly priced for what it does for you. Much better way of doing it and cheaper than the parts for a passive would be.

 

[Bassmec]

You don't just wire them all together like that when using a crossover....that's going to end badly.

Think of it as 2 separate speaker systems that just happen to be all mounted in 1 box.

On the low side, you have three 8ohm woofers. Your impedance options there are 2.67ohms all in parallel or 24ohms all in series while keeping equal power distribution amongst all the woofers. Neither of those make much sense.

The la6cbmr has an fs close to 500hz. Rule of thumb there would be to pass at 1khz, though you could get away with 800 using a 3rd order filter.


Easiest solution would be to add a 4th bp102. Then you could have a nominal 8ohm cab on both sides of the crossover. Eminences 800hz 2-way would get you up and running and sound alright while you hone your skills and work up a more purpose built, high power handling crossover. Four bp102's can take a lot of power and the off-the-shelf crossover would be the weak link in the system.


As for the HPF down low, a passive filter that could do that would consist of an incredibly costly array of parts and doesn't make much sense either. I've never had a problem blowing woofers with no HPF but if it is a concern, TB'er fdeck's unit is the answer there. It does it actively before the cab, is adjustable and is very modestly priced for what it does for you. Much better way of doing it and cheaper than the parts for a passive would be.

GustavFL This is very true and what will33 hasn't mentioned is insertion loss and phase differential to other active loudspeakers that will be reproducing your sound via your DI out.

Best thing to do all round is make a 5X10 and think about using
A high pass filter only, and let the bass drivers roll off by them selves

As long X max tens they will tend to do that before they reach any serious beaming effects.

PS Vertical arrays work better than simple square boxes so make two trapezoidal 2x10's, and horn load the midrange driver in a separate box
Also containing the input socket and crossover and series output sockets
For the 2x10's.

But thinking differently.
I am sure you don't want to end up making something custom that is so similar to the minimalist ease of mass production stuff, use your South American flare for design.
PS do you have any idea how beautiful light an strong close grained Brazilian cedar trees are.
If I lived in Brazil, I would have a cab made from a hollowed out windfall tree sorn off at the root bowl as a wide stable base and just pop a baffle board and ports in that.
Think of a very short dug out canoe flaring to a broad flat transom, standing vertical. who needs truck bed liner when you have tree bark.

 

[Arjank]

The la6cbmr has an fs close to 500hz. Rule of thumb there would be to pass at 1khz, though you could get away with 800 using a 3rd order filter.

It's possible to even cross it at 700hz with just a 12db/oct filter in conjunction with an LCR that flattens the impedance peak of the la6cbmr.
This will also spare you a costly series capacitor(you need two for an 18db/oct highpass), don't use a standard bipolar electrolyt cap but use at least an MKT(foil cap).
The LCR can do with a cheaply (high impedance) core inductor and an bipolar electrolyt cap.

And, a 18db/oct crossover is more sensitive when it comes to choosing the correct component values.

 

[GustavFL]

Thanks for the answers guys.

The midranger is an Alpha 6-CBMRA not an LA6-CBMR, its Fs is 407 Hz, so how low can I highpass it while protecting from lows?

Considering what you mentioned, and that I'm not willing to spend more with drivers (stuff here is not as cheap as in the US ) I'm inclined to build 2 cabs, would this solve the matter or is it almost the same?

- One 210 with 2 BP's wired in series for a 16 ohms load
- One 110/6 with 1 BP and the Alpha wired in series for a 16 ohms load with a highpass for the midranger, an output to the 210 so when chained they would have 8 ohms.

This set would be nice 'cause I can carry just the 110/6 when little power is needed and with 16 ohms the amp wouldn't force it too much. It's a GK MB500, 500W@4ohms and 350W@8ohms.

@Bassmec - Great enthusiasm man
I'm planning to use 15 and 18 mm naval cedar plywood, it's not the same as solid wood but I think it will give a strong and light cab.

In the case of building the 110/6 how should I wire the filter there? Sorry my knowledge in electronics is quite limited

 

[CL400Peavey]

Thanks for the answers guys.

The midranger is an Alpha 6-CBMRA not an LA6-CBMR, its Fs is 407 Hz, so how low can I highpass it while protecting from lows?

Considering what you mentioned, and that I'm not willing to spend more with drivers (stuff here is not as cheap as in the US ) I'm inclined to build 2 cabs, would this solve the matter or is it almost the same?

- One 210 with 2 BP's wired in series for a 16 ohms load
- One 110/6 with 1 BP and the Alpha wired in series for a 16 ohms load with a highpass for the midranger, an output to the 210 so when chained they would have 8 ohms.

This set would be nice 'cause I can carry just the 110/6 when little power is needed and with 16 ohms the amp wouldn't force it too much. It's a GK MB500, 500W@4ohms and 350W@8ohms.

@Bassmec - Great enthusiasm man
I'm planning to use 15 and 18 mm naval cedar plywood, it's not the same as solid wood but I think it will give a strong and light cab.

In the case of building the 110/6 how should I wire the filter there? Sorry my knowledge in electronics is quite limited

No, the 10/6 cab will have the total impedance of the 10" driver, so it would be 8 Ohms I believe. You would want the 210 to be a 4 Ohm cab, to split the power between all the woofers correctly. You would also still need a LPF for this scenario on the 210 cab.

 

[GustavFL]

I don't get it, why the 10/6 would be 8 ohms with two 8 ohms drivers wired in series?

Wouldn't it work smoothly if I just let the woofers roll off by themselves?

 

[CL400Peavey]

I don't get it, why the 10/6 would be 8 ohms with two 8 ohms drivers wired in series?

Wouldn't it work smoothly if I just let the woofers roll off by themselves?

The 10 and the 6 are not in series. The cross over splits the signal appropriately. Effectively your amp only sees one load, the cross over which is loaded with the woofer and the mid driver.

 

[GustavFL]

CL400, would it be that way even if it's not a crossover, just one 3rd order butterworth high pass filter for the mid ranger @700Hz?

 

[GustavFL]

I would like to make use of alpha's high response between 400Hz and 1 kHz

 

[will33]

Wrong mid driver for this application then. Passing it at or below fs will fry it with any power. Look for regular 6's with fs in the 100's and load it in a subchamber.

The 3 woofers is still an issue with impedance. You could do it that way with a 2ohm stable amp and this being your only cab. You could also "cheat" and just run a HPF only on this 6, set up where the woofers start losing response, probably 1500-2000 hz. That should keep your impedance OK as the woofers impedance should be rising pretty good by then and there isn't much power demand up there.

The whole cab would still be a nominal 2.67 ohms with 3 woofers and one 6".

 

[will33]

The insertion loss and LCR networks and stuff is a bit beyond my skill level. I understand what they are/what they do, but can't just throw you out some part values and say " do this ".

 

[GustavFL]

Using just a HPF in a 110/6 cab for the 6'' start acting to fulfill woofer's response and building another 210 cab, both 16 ohms would be nice, so when chaining them I would get 8 ohms.

The 2.67 load is for 3 woofers wired in parallel. For the 110/6, doesn't the 6'' interfer with impedance in the circuit?
Wiring it in series with the 10'' in a cab doesn't result in a 16 ohms load or wiring it in parallel results in 4 ohms for this cab? Being said that it's only one filter? Maybe even as 1st order, just one capacitor.

 

[Bmorefoozler]

If you use a crossover there is no series, there is no parrallel. IF there is a crossover, the two speakers behave as one, generally speaking impedance wise.

 

[GustavFL]

I see, what about only filtering the mid driver 2nd order at 1.5 kHz? Would that change how to calculate impedance in the system?

 

[Bmorefoozler]

I see, what about only filtering the mid driver 2nd order at 1.5 kHz? Would that change how to calculate impedance in the system?

not really. The woofer is likely very high impedance by that point.

 

[GustavFL]

Thanks. Considering that any component has it's resistance, adding a capacitor and an inductor wouldn't affect system's impedance?

Would I be able to get 2 cabs with nominal impedance of 16 ohms wiring each pair of drivers in series?

 

[CL400Peavey]

Thanks. Considering that any component has it's resistance, adding a capacitor and an inductor wouldn't affect system's impedance?

Would I be able to get 2 cabs with nominal impedance of 16 ohms wiring each pair of drivers in series?

No. Because you are never running the mid driver in series or parallel with the woofer. If the cross over is correct, it is effectively the same speaker.