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DSP Speaker/Amp/Effects Management Redux

Passinwind

Passinwind

I know nothing.
Dec 3, 2003
23,045
45,909
Columbia River Gorge, WA.
passinwind.com
Disclosures
Designer/Toaster Tech @ Passinwind Electronics
#1
I am in the throes of my last two lounge jazz gigs on EUB. When that's done I will be going back to original psycho-fusion music, and much of the time that'll entail just bass and drums in the literal sense. Also, as some of you know, I have a bent for DIY cab and preamp building, and I figured a good DSP appliance would be helpful in that regard. Finally, I am putting together a new PA and a speaker management system is mandatory these days as far as I'm concerned.

So to kick it off, here's the unit I bought recently: [Invalid or Expired Link Removed] . I also have a SpeakerPower amp module with another very powerful DSP unit built in, which I've posted about here numerous times. It's more or less the same one used in the Berg IP series, FWIW. Both have their advantages and disadvantages, as usual. I'll concentrate on the Rane unit for the moment though.

My conception of a bass rig requires at least three amp channels and three cabs. One channel is dry and full-range at all times, and should be capable of carrying the room by itself in situations where no FOH support is available. The other two channels could be stereo delayed in a spread across the stage (a la Pat Metheny's rig), split for separate processing of highs and lows, used for mixing distortion in the way Amy from Clatter does (with a separate tube guitar amp as one channel, for example), or used in a number of other ways as imagination dictates. Beyond that, I want the ability to send one or two DI feeds to the house that are delayed to the backline if the situation is workable for that.

The Rane RPM26z will do allow me to do all those things, plus stereo EFX mixing, a bunch of EQ and compression processing, expression pedal implementation and preset patch switching, and a lot more. Phew...it's been a busy week writing test programs for this thing!:cool:

I have to say, this has the nicest interface I've yet seen for this sort of application. Imagine routing options something like the Boss GT series units, but with extensive mixing and patching capabilities beyond that. If you hook up a laptop, you can edit in real time and save patches, then just use a small floor switcher and/or a few expression pedals or panel-mounted pots to do continuous control of quite a few parameters, with no computer needed at that point. I'll post a screenshot or two to illustrate what I mean a little later.

Questions or comments?
 
#2
You're nuts, Charlie. I mean that in the best possible sense.

Seriously -- that's a whole lot to chew on from a programming/setup point of view, but the flexibility it affords positively boggles the mind. :eek:

If you ever come out with a two-channel tube preamp, I'll be first in line. :cool:
 
#4
bongomania said:
Definitely keen to hear more about this system!
Click to expand...

Ok, here's a pretty simple config I was playing through this afternoon:

Link Removed

This one has a two band compressor for the dry channel, which is bypassable. There's parametric EQ both before and after the compressors. The compressors have sidechains, but I didn't use 'em this time. The dry channel drives my SpeakerPower amp, producing up to 1000 watts/4 ohms, which goes into my Schroeder 21012. If I need more, I can sub in my PLX 1802, good for 1800 watts bridged.

Then I have two EFX sends, and either or (both) can be pre or post those compressors. I could also just give them their own compressors if I felt like it as well. The EFX sends go to the analog inputs of my Lexicon MPX-550. They return to the Rane unit through its digital inputs. Parametric EQ is independently available both pre and post the EFX unit. Oh, yeah: any of those parametrics can do up to 15 bands if desired.

Each EFX output channel drives one channel of my PLX 1804, at 550 watts/8 ohms per side. Today I was running an Accugroove Tri-112L on one side, and my DIY 3-way cab on the other one.

Finally, there's an adjustable DI feed with EQ and a delay to time align to FOH if desired.

Needless to say, this sounds fairly big.:bassist:
I had a chance to dial in a lot of the details through a laptop, and it's trivially easy to save the real time changes for later recall.

The next step will be to take a real time analyzer to the club I work at, and work out some EQ curves and presets. The hardware can store 24 presets at a time, 8 of which are accessible without using an external computer.

When all this is said and done, I've only used 55% of the CPU overhead, so I can add lots more bells and whistles if I can find a reason to do so.

BartmanPDX said:
You're nuts, Charlie. I mean that in the best possible sense.
Click to expand...

But wait: there's more! That doesn't include the DSP in the SP amp, which is actually already pretty dialed in for the Schro cab.:rolleyes:
 
#5
BartmanPDX said:
Seriously -- that's a whole lot to chew on from a programming/setup point of view, but the flexibility it affords positively boggles the mind. :eek:
Click to expand...

Fortunately the Rane software appears to be finished and easy to work with, while the SpeakerPower stuff is really not even good enough to attract much of an OEM market. Pity, because the product it [un]supports seems to be worthy of so much more.
 
#6
Most FOH engineers at even the bar band level have been using the analog separates approach of what a SMS (speaker management system) for decades now. A primary benefit of DSP-driven SMS is that you can deal with tailored presets for any venue, system, and set of needs with a lot less rack space and weight involved, perhaps simplify the gain-structuring and definitely the cabling and routing of a system, and with presets have a level of reproducability that wasn't affordably available.

Applying SMS to a bass rig, even a fairly simple one, can have benefits too. If one wants to replace or add better EQ and compression, limiting, excursion control via high-pass filters, bi-amping to a system, it can be doen in one rack space or less (see the QSC DPS-4 for a unit that can be put behind other rack equipment and weighs less than 2 pounds).

Furthermore, if you are operating sound from stage or want to feed a sound engineer a massaged and plug-and-play signal that's like a super DI that can be done simultaneously. You can send a signal without corrective stage-rig EQ - actually can have its own EQ curve, already have acceptable levels of compression that should need no fuirther FOH tweaking, etc. It's one way to almost idiot-proof your FOH sound if you understand your goals and have even a mediocre FOH engineer.

And when you get intom more complex backline scenarios such as Passinwaind is presenting here, it's really preferable to expensive automated mixers and more rackage.

I do have one concern about the mutliple stage rigs/mixes though, Charlie: how will you handle the destructive cancellation/reinforcement issues that separate placements of low frequency sources is sure to introduce?​
 
#7
This looks brilliant. It's just a little expensive.
The instant recall of presets and little things like dual band compression and FOH delay would make it well worth it. And you have plenty of IO/Cpu left to help the keyboard player.

It will be interesting to see what gets used in the long term and if just the used features could be combined in some standard rigs.
 
#8
greenboy said:
I do have one concern about the mutliple stage rigs/mixes though, Charlie: how will you handle the destructive cancellation/reinforcement issues that separate placements of low frequency sources is sure to introduce?
Click to expand...

Oddly enough given my rudimentary knowledge here, that thought had crossed my mind as well. I've dealt with multiple subs in home theater applications before and it can be a concern there, though it's minimized through careful placement of the speakers, and usually results in a better (more neutral/flat) frequency response when done right than with a single speaker.
 
#9
greenboy said:
I do have one concern about the multiple stage rigs/mixes though, Charlie: how will you handle the destructive cancellation/reinforcement issues that separate placements of low frequency sources is sure to introduce?
Click to expand...

Great question, and one that comes up all the time.

Not all the sources need to produce the lower frequencies, first off. And they do not all need to be nearly equal in volume either, especially with time domain effects or radical distortion. I'm not ruling out a full surround-sound solution either, but mainly I just keep it (the acoustic soundstage) moving and embrace what it brings to the table. I don't need it to sound "the same for everyone in the room", and I've had phenomenal reaction to my stereo rigs for many years. Once people understand where the sweet spot is, they tend to want to be there. Hmmm...bring 'em down in front, what a concept.

Metheny talked a bit about the difference between mixing phased/chorused/delayed signals in air, or doing out of one driver. Once I grokked that, there was no going back. Single source bass amps just sound really, really boring to me. YMMV, and Bart probably has it right anyway!:cool:

OTOH, you can just use the Rane appliance similar to the way Mr. Bergantino did if that floats your boat.
 
#10
seamonkey said:
This looks brilliant. It's just a little expensive.
The instant recall of presets and little things like dual band compression and FOH delay would make it well worth it. And you have plenty of IO/Cpu left to help the keyboard player.

It will be interesting to see what gets used in the long term and if just the used features could be combined in some standard rigs.
Click to expand...


I also play guitar synth in Passing Wind (so sometimes I am the "keyboard player"), and IME the triggered samples absolutely need to be in stereo to sound right. I'd prefer to have different EQ available when I switch instruments as well, so for me the economy isn't that bad compared to carrying three parametric EQs. Still, I bought this unit mainly for PA use, but I'd like to stir the pot a bit in the fashion you're suggesting.

BTW, that compression can be however many bands you want, within reason at least.
 
#11
I just wish the software wasn't PC-only. So much good utility software out there is not Mac-compatible. I'm planning on buying a PC just so I can use circuitboard layout software, which there are like three or four well-designed programs for PC and only one sucky one for Mac.
 
#15
Passinwind said:
Not all the sources need to produce the lower frequencies, first off. {...}
Click to expand...

Sure, but for those that do, I'd probably be prone to doing the stereo/whatever spread above a certain frequency as satellites and doing my sub around the "either pretty darn close, or a waveform or more further away" method.
 
#16
greenboy said:
Sure, but for those that do, I'd probably be prone to doing the stereo/whatever spread above a certain frequency as satellites and doing my sub around the "either pretty darn close, or a waveform or more further away" method.
Click to expand...


Metheny said go at least 15 feet between each cab, and that was for guitar.;) I've done it both ways, and both work pretty well IME. I haven't really started in fine tuning apparent spacing with the DSP yet, but that's an interesting can 'o worms in it's own right.
 
#18
BTW, though I am deaf in one ear, I used to run a 4-bus quad rig with 4 biamped cabs for my electronics and saxes rig. I'm kinda getting stoked about using two satellites crossed over to a central sub for a stereo bass guitar rig. The V-Bass allows for a certain amount of useful imaging this way, and a SMS would be ideal to complete the scenario.
 
#20
bongomania said:
I just wish the software wasn't PC-only. So much good utility software out there is not Mac-compatible. I'm planning on buying a PC just so I can use circuitboard layout software, which there are like three or four well-designed programs for PC and only one sucky one for Mac.
Click to expand...

The newer Macs use Intel processors, which means they will also run windows. If you get Parallels, you can even run both operating systems simultaneously.

http://www.parallels.com/en/products/desktop/
 

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