Help with a Low Pass filter for my single 15" cab

jibreel · #1 04-25-2011, 03:55 PM

I have a single 606 cab with a 3015 that sounds GREAT for what it is. I am pairing it with an Acoustic Image sealed cab: downward firing 10 with a 5 and a 1 out the front. VERY high fidelity. The 10 is an Eminence Neo. The 1 is probably voiced too high for bass anyway. Both cabs are 8 ohms so I daisy chain them and they sound great.

As BurningSkies pointed out to me in the main fEarful thread :I’m also guessing that if the 3015 isn’t low passed at a certain point you’re getting a very mid/upper mid forward tone that may beam pretty seriously? He is correct.

The AI cab kicks some serious sound for its size and I know it can handle the mids, especially in the smaller rooms I play.

So, I am wanting to try installing a low pass filter in the 606. http://www.eminence.com/pdf/Kappalite_3015.pdf

I have emailed Rick form Acoustic Image to get his suggestions but of course can't wait

so I am asking you all.

Any suggestions? Can it be sweepable? Here are the cabs:

Thanks !!

rpsands · #2 04-25-2011, 04:13 PM

What kind of amplifier are you using? If you've got a stereo or parallel mono amp it might be a good idea to just use a dsp tool (e.g. a bbe ds24).

jibreel · #3 04-25-2011, 04:34 PM

Quote:

Originally Posted by rpsands

What kind of amplifier are you using? If you've got a stereo or parallel mono amp it might be a good idea to just use a dsp tool (e.g. a bbe ds24).

Right now it is a TC Classic 450. One speakon out. I daisy chain the two cabs.
Planning on getting a 70's Ampeg V4B so that will be in the mix also.
Ideally, it would be in the cab as on on/off or sweepable [ if that is possible ]. I would really like to not have another external piece of gear if I can avoid it.

jibreel · #4 04-25-2011, 07:51 PM

Is this chart correct ? What components do I need to make a crossover?

Once I figure out the frequency is 6 or 12 db best?

Of course I would like an on/off and ideally sweepable.

Pretty obvious I am floundering in uncharted skill levels

rpsands · #5 04-25-2011, 08:24 PM

Sweepable doesn't work with passive crossovers. On/off yes with a switch.

If it were me in your situation I would probably start selling cabs and order a 12/6 from someone.

If you must mod what you have, I'd consider starting with an Eminence 500hz off-the-shelf board and seeing if that does what you want it to do -- if it gets you in the close ballpark, then you might be on the right track and want to invest all the energy in learning about crossover design and such.

will33 · #6 04-25-2011, 09:07 PM

I'd try to borrow a biampable bass head or pull the crossover from the PA rack or something to experiment with different settings to find something you like. Otherwise, a single inductor about 2.5mh or so would lowpass it at 6db/octave somewhere close to 500hz. Turns out that's not what you want, well, then you have another extra part to throw in the bin.

Even if you just lowpassed the 15, it'll still be interfering with the downfiring 10 in the other cab unless you took the 10 out of the equation all together. Maybe need more switches.

jibreel · #7 04-25-2011, 11:12 PM

Thanks all for responding.

The Eminence 500hz board looks promising. Only $34.00. They also have a 250HZ board. Would that be better?

Probably best for me to find someone and pay them for help here in the city. Given my cab/volume needs, I am really hoping the TC12AF cab I have on order will take care of 90+% of my gigs. I am really happy enough with the 606/3015 and the one AI cab so I have backed off on my fEarful gas for now. I do want to experiment with the low pass filter.

jibreel · #8 04-26-2011, 07:51 AM

Tried a bi-amp experiment:

TC Classic 450 into the Acoustic Image 10/5/1 cab only.

DI out [ pre eq ] from the 450 into an Acoustic Image amp. Acoustic Image amp into the 606/3015 cab.

Wow !!! Sounds great !! Separate EQ for each obviously.

Ideally, I would like to not have to use both amps though so still interested in a low pass filter for the 606/3015.

will33 · #9 04-26-2011, 07:58 AM

Let's back this up a little bit. Your top cab is already a 3-way but I assume it's not loud enough on it's own? What you're doing by adding the 15 is essentially adding more woofer to the overall system. Should maybe open up the top cab and reverse engineer it's crossover to see where that 5 is highpassed at. That would be the same spot you'd want to lowpass the 15. Then put a switch to take the top cabs 10 out of the equation when the 15 extension is being used.

jibreel · #10 04-26-2011, 08:18 AM

Quote:

Originally Posted by will33

Let's back this up a little bit. Your top cab is already a 3-way but I assume it's not loud enough on it's own? What you're doing by adding the 15 is essentially adding more woofer to the overall system. Should maybe open up the top cab and reverse engineer it's crossover to see where that 5 is highpassed at. That would be the same spot you'd want to lowpass the 15. Then put a switch to take the top cabs 10 out of the equation when the 15 extension is being used.

I do really appreciate you taking the time to respond. I probably should educate myself a little more on this whole crossover business before I take up any more of peoples time.

Actually, the AI cabs are amazingly loud for their size. I daisy chain two of them and they are more than loud enough for the gigs I do. They just can not do the FULL low end that the 15 provides. The 15 and a 10 really sound great together, especially bi-amped. Just trying to get away from using two amps.

Although I do not know for sure, I strongly suspect that the 5 in the AI cab is not " heavy duty" enough to pull off the mid duty for bass. So I will need to keep the 10 in the loop. When I bi-amped, I was able to change both the tone and vol of the 15 and it really sounded better.

Because I am so hoping that the TC12AF I have on order will be my main gigging cab, I will probably not want to mess with the AI crossover. Way over my head at this point.

Can't hurt to give the Eminence low pass board a try.

So I guess my final question is: 250 or 500 hz on the Eminence board ???

Thanks again.

will33 · #11 04-26-2011, 08:27 AM

250 would pretty much turn it into a subwoofer. 500 would be more like a "bass cab woofer". You've got both amps there, mess with crossover points and see which you like better.

will33 · #12 04-26-2011, 08:32 AM

You operating each cab with a separate amp but don't have an actual crossover? If so, you can mimic by eq'ing all the highs out of one and all the lows out of the other but that's really getting into guesswork. If I was shooting craps, I'd bet on the 500. Pick up a switch so you can still run the 15 fullrange if you want. At least then it's not a dedicated lowpass, leaves options open in the future, other cab combinations, etc.

Matthijs · #13 04-26-2011, 08:34 AM

You don't have to mod the cab's. You can also build a external crossover by installing the eminence board in a handy seperate enclosure.

As to the frequency: chances are the 10" is crossed over quite low, as it is downfiring. I'd go for a very low crossover point, to keep as much of the 10"s sound in there, so that's the 250 hz board. That's also probably best for the power distribution.

Matthijs · #14 04-26-2011, 08:36 AM

Oh ,and I forgot: make this a real crossover, not just a low pass on the 15".

jibreel · #15 04-26-2011, 08:41 AM

Quote:

Originally Posted by Matthijs

Oh ,and I forgot: make this a real crossover, not just a low pass on the 15".

Thanks again all !!!

So is this a real crossover/low pass filter:

EMINENCE_PXB 250 PXB_250

jibreel · #16 04-26-2011, 08:43 AM

Quote:

Originally Posted by will33

You operating each cab with a separate amp but don't have an actual crossover? If so, you can mimic by eq'ing all the highs out of one and all the lows out of the other but that's really getting into guesswork. If I was shooting craps, I'd bet on the 500. Pick up a switch so you can still run the 15 fullrange if you want. At least then it's not a dedicated lowpass, leaves options open in the future, other cab combinations, etc.

Yes on the switch. I do want that option.

Thanks

MuzikMan · #17 04-26-2011, 08:52 AM

Quote:

Originally Posted by jibreel

Thanks again all !!!

So is this a real crossover/low pass filter:

EMINENCE_PXB 250 PXB_250

That is not the right crossover for the job. You want a 2-way 250hz crossover. If you put this board in its own box with a single input jack and two outputs for high and low pass you won't need to rewire any of your cabs and no switch will be necessary.

jibreel · #18 04-26-2011, 09:07 AM

Quote:

Originally Posted by MuzikMan

That is not the right crossover for the job. You want a 2-way 250hz crossover. If you put this board in its own box with a single input jack and two outputs for high and low pass you won't need to rewire any of your cabs and no switch will be necessary.

I found this: EMINENCE_PXB2 500 PXB2_500

But it is 500 HZ. I could not find a 250 HZ 2-way.

And just to make sure I understand, it would be:

Amp > crossover box input

High to my smaller cab
Low pass to the 15 cab

Is this correct?

Thanks again

BurningSkies · #19 04-26-2011, 09:35 AM

Quote:

Originally Posted by jibreel

I found this: EMINENCE_PXB2 500 PXB2_500

But it is 500 HZ. I could not find a 250 HZ 2-way.

And just to make sure I understand, it would be:

Amp > crossover box input

High to my smaller cab
Low pass to the 15 cab

Is this correct?

Thanks again

If you're going to experiment with a crossover setup with these cabs, I'd certainly be looking at either the 500hz or 800hz. Especially give you're talking about a 3015 rather than a 3015LF. 250hz wouldn't be providing too too much signal to the 15" before the roll off, would be my guess.

Also be aware that a generic passive crossover is only going to go so far. Good passive crossovers take a lot of different information into account, and an off the shelf unit can't really address most of that.

MuzikMan · #20 04-26-2011, 10:16 AM

Quote:

Originally Posted by jibreel

I found this: EMINENCE_PXB2 500 PXB2_500

But it is 500 HZ. I could not find a 250 HZ 2-way.

And just to make sure I understand, it would be:

Amp > crossover box input

High to my smaller cab
Low pass to the 15 cab

Is this correct?

Thanks again

Yes, that is correct. Just keep your expectations realistic. With a passive crossover network you have no control over level matching. If your cab's relative volumes are good then there is no issue. You will hear from the experts that an off the shelf crossover doesn't match the specific requeirements of every unique driver (such as actual impedance, not rated). While this is true, I have found through experimentation that a quality off the shelf unit used in the correct manner can certainly provide good results in a bass cab. If you were designing audiophile quality studio monitors then a custom crossover would be highly beneficial IMO.