4-way / 8-out DSP?

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monekh
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4-way / 8-out DSP?

#1 Post by monekh » Wed Oct 28, 2015 3:28 pm

does anyone have any recommendations or experience of management systems with 4-way crossover capabilities?
so far I've come across the following with 8 outputs:

Driverack 480
Peavey VSX48
BBE DS48

if there are others to look into or avoid, please let us know!
cheers

NukePooch
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Re: 4-way / 8-out DSP?

#2 Post by NukePooch » Wed Oct 28, 2015 3:50 pm

Ashly Protea 4.8 @ speakerhardware.com

Never seen it or used it, I just remembered seeing it on Leland's site.
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BrentEvans
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Re: 4-way / 8-out DSP?

#3 Post by BrentEvans » Wed Oct 28, 2015 3:53 pm

Ashly protea 4.8sp , ashly 24.24, symetrix solus,

Also don't forget that you can split the feed to two driverack pa2 units or dcx2496s.
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Re: 4-way / 8-out DSP?

#4 Post by Grant Bunter » Wed Oct 28, 2015 4:04 pm

A couple of people have well recommended Ashly Protea series processors.
http://www.ashly.com/products/protea-sy ... essors.php

The Ashly 4.8SP has what you want 4 in /8 out.

And it's available from Leland at www.speakerhardware.com , reduced to under $1K...
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SoundInMotionDJ
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Re: 4-way / 8-out DSP?

#5 Post by SoundInMotionDJ » Wed Oct 28, 2015 10:45 pm

monekh wrote:does anyone have any recommendations or experience of management systems with 4-way crossover capabilities?
The Behringer DCX-2496 has six outputs, and all are independent. So, it can achieve four independent output channels.

If you need eight outputs, then you need eight. If you can make something work with four (or six), than this might be an option.
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monekh
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Re: 4-way / 8-out DSP?

#6 Post by monekh » Thu Oct 29, 2015 6:06 am

great, will have a look at the Ashly Protea series.
BrentEvans wrote: Also don't forget that you can split the feed to two driverack pa2 units or dcx2496s.
I hadn't considered this - do you mean send, for example, the hi output from one unit to the input of the other in order to further split the hi frequency band? Or would there be a better way of doing this, splitting the signal before both units?
SoundInMotionDJ wrote: The Behringer DCX-2496 has six outputs, and all are independent. So, it can achieve four independent output channels.

If you need eight outputs, then you need eight. If you can make something work with four (or six), than this might be an option.
another solution I hadn't thought of - this is all theoretical at the moment but we are contemplating building mid-subs, perhaps T30s, to go inbetween our T60s and Omni12s... and if we did this we would in fact just need two mono channels for sub and mid-sub bands below 100Hz. in which case 6 outputs would suffice.

however we've scuppered ourselves with a pa2 there because as far as I know you can't unlink the stereo outputs / the software doesn't allow for more imaginative routing than 3-way. so would still need to switch it for something more flexible.

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Re: 4-way / 8-out DSP?

#7 Post by BrentEvans » Thu Oct 29, 2015 8:25 am

Split the signal coming from the mixer and adjust each band separately. I'd put the lows on one unit, mids and highs on the other. That way you can still use the auto EQ on your tops at least. It never does much for subs anyway.

With dcx you can do left/right or as above. It has more routing flexibility.
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Re: 4-way / 8-out DSP?

#8 Post by Ryan Sober » Thu Oct 29, 2015 8:39 am

monekh wrote: another solution I hadn't thought of - this is all theoretical at the moment but we are contemplating building mid-subs, perhaps T30s, to go inbetween our T60s and Omni12s...
Why? That sounds like a huge increase in pack space and amplifier power for no real gain. Your T60's should be able to handle everything below 100Hz, no problem.

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Re: 4-way / 8-out DSP?

#9 Post by monekh » Thu Oct 29, 2015 9:38 am

Ryan Sober wrote: Why? That sounds like a huge increase in pack space and amplifier power for no real gain. Your T60's should be able to handle everything below 100Hz, no problem.
might be a discussion for a separate thread but for the type of music (dub, jungle) we're playing we'd like to be able to crossover to the T60s lower than the Otop12s will allow... you're right the T60s can certainly handle up to 100Hz with ease but at the moment the crossover at that frequency seems messy and the weakest point, even with eq - we were pondering whether building separate cabinets to handle that region (aorund 60-100) might give us a tighter/stronger sound and also allow us to isolate/kill sub frequencies lower with less interference from mid-sub frequencies.

anyway we need to get to know everything better before doing that, and make sure we're not making it too complicated for ourselves, which we probably are! just scoping out the possibilities. could be we just need to work on the crossovers a bit.

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Re: 4-way / 8-out DSP?

#10 Post by Tom Smit » Thu Oct 29, 2015 10:37 am

monekh wrote:
Ryan Sober wrote: Why? That sounds like a huge increase in pack space and amplifier power for no real gain. Your T60's should be able to handle everything below 100Hz, no problem.
+1
monekh wrote: might be a discussion for a separate thread but for the type of music (dub, jungle) we're playing we'd like to be able to crossover to the T60s lower than the Otop12s will allow...
Have you considered the DR280?
monekh wrote:
anyway we need to get to know everything better before doing that, and make sure we're not making it too complicated for ourselves, which we probably are! just scoping out the possibilities. could be we just need to work on the crossovers a bit.
Yup. Try different slopes and different filters.
TomS

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SoundInMotionDJ
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Re: 4-way / 8-out DSP?

#11 Post by SoundInMotionDJ » Thu Oct 29, 2015 3:39 pm

monekh wrote:we are contemplating building mid-subs, perhaps T30s, to go inbetween our T60s and Omni12s.
No

:cop:

No, no, no, no, no, no, no. No!

Stop right there. There is ZERO reason to put a box between a T60 and O12's The amount of power needed to bridge between the efficient use of those two cabinets (or really any sub/top pair here) is minuscule compared to the added complication. The differing responses of the T60 and T30 in the 80-160Hz range will frustrate any attempts to integrate the sound. And you'd need 2 or 3 Y30's to come anywhere near the output of a single T60.

Stop. Do not pass go. Back slowly away from the bad idea. :mrgreen:
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Re: 4-way / 8-out DSP?

#12 Post by DJPhatman » Thu Oct 29, 2015 4:02 pm

Tom Smit wrote:Have you considered the DR280?
A BIG +1. As you can see by the charts below, You could cross over from the T60 to a DR280 @80hz. It will take twice as many OT12s to cross over @100Hz. Adding another set of cabinets would be a foolish waste, IMHO. Build DR280s and re-use most of the components from the OT12s into the DR280s. Worst case scenario is you tri -amp, which can be easily done with any DSP that has 3 outputs. Adding T30s will not get you there, unless you build with the 3012LF and to the widest width,27" (which is unlikely, since you are in the UK). Build a pair or 2 of the DR280, and 2-4 T60s. I hope you have access to a lorry to transport your system!



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Re: 4-way / 8-out DSP?

#13 Post by Grant Bunter » Thu Oct 29, 2015 4:29 pm

There's other ways of approaching the problem a well.
How many Otops are you using?
If it's a pair, then adding another pair will increase output by 6dB at the crossover point. That may make the problem disappear, and you would get benefits in smoothing mids/HF response.

What type of slope are you using?
Butterworth slopes have a summing effect at the crossover point, putting a bump in response.
If you are currently using LR slopes, which leave a slight dip in response at the crossover point (unless you manipulate your sub low pass and tops high pass frequencies), then changing to BW might make the difference as well...
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Re: 4-way / 8-out DSP?

#14 Post by CoronaOperator » Thu Oct 29, 2015 5:18 pm

monekh wrote:
Ryan Sober wrote: at the moment the crossover at that frequency seems messy and the weakest point, even with eq -
If EQ isn't helping/has no effect, then you probably have phase issues between tops and subs or possibly a boundary reflection causing cancellation. Adding EQ in that case only makes for a bigger argument with no audible result. Do you have access to a measurement mic? Free software like Room EQ Wizard can help you see what is going on with RTA and phase plots.

One method for aligning phase without any measurement tools other than a SPL app on your phone is to invert the polarity of your tops on your DSP. Play a 100hz sine wave (or whatever your crossover is at) then increase the phase/delay (whatever your DSP has) of your tops until you find a point where the SPL is at a MINIMUM at the listening position. Once you find that point, switch the polarity of your tops back to normal. Of coarse if the problem is a room reflection then you will have to experiment with different sub locations.
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Re: 4-way / 8-out DSP?

#15 Post by CoronaOperator » Thu Oct 29, 2015 5:35 pm

monekh wrote: but for the type of music (dub, jungle) we're playing we'd like to be able to crossover to the T60s lower than the Otop12s will allow...
Dubstep eh? You wouldn't by chance have the subs 10-20 dB's louder than the mains?

Consider this 80 hz DSP crossover setting:
Image

Now we do nothing but turn the gains up on the subwoofer channel (DSP still at 80hz):
Image
Now the acoustic crossover has jumped up to ~135 Hz even though the DSP says 80hz. The actual acoustic crossover may be very different than what your DSP says depending on the output of your tops vs subs.

The solution in this case would be to keep the tops at 80hz crossover (DSP) but run the subs crossed over around 50hz (DSP setting) or so. The resultant acoustic crossover would then return back to the 80hz intended. There would be no hole in response as some would expect as the crossover is a slope, not a cliff. Again something like Room EQ Wizard could help you here but experimenting by ear may also solve your problem.
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience

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