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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Installed Sound/Contracting => Topic started by: Kevin Moese on February 11, 2016, 12:50:37 pm

Title: "Manual" room combining without DSP
Post by: Kevin Moese on February 11, 2016, 12:50:37 pm
Hi all, anyone have any experience wiring up those old toggle switch-based room combining systems?  I've been trying to find a wiring diagram with no luck. 
Title: Re: "Manual" room combining without DSP
Post by: Scott Carneval on February 11, 2016, 12:54:46 pm
Hi all, anyone have any experience wiring up those old toggle switch-based room combining systems?  I've been trying to find a wiring diagram with no luck.

Do you have a brand and model number?
Title: Re: "Manual" room combining without DSP
Post by: Kevin Moese on February 11, 2016, 01:03:32 pm
Do you have a brand and model number?
It's those old Toa 900-series preamps, but the combining is just DIY radio shack toggle switches mounted to a panel.  Somehow those switches run in-line with the preamp output for each zone i think, and flipping them effectively combines the zones.  Does that make any sense?
I'm not on-site, all i have to go on are some pictures of the front of the rack.. i don't know whats going on behind it.
Title: Re: "Manual" room combining without DSP
Post by: Scott Carneval on February 11, 2016, 01:23:59 pm
It's those old Toa 900-series preamps, but the combining is just DIY radio shack toggle switches mounted to a panel.  Somehow those switches run in-line with the preamp output for each zone i think, and flipping them effectively combines the zones.  Does that make any sense?
I'm not on-site, all i have to go on are some pictures of the front of the rack.. i don't know whats going on behind it.

I would pull all of that out and start from scratch, or walk away. Who ever DIY'd the system is going to be your only resource, and they should be the ones servicing this.

When starting from scratch I would use an install DSP such as Ashly 24.24, QSC Q-Sys, or a dedicated FSR room combining system. Commercial systems need to be reliable, repeatable, scalable, and serviceable.
Title: Re: "Manual" room combining without DSP
Post by: Kevin Moese on February 11, 2016, 01:34:31 pm
I would pull all of that out and start from scratch, or walk away. Who ever DIY'd the system is going to be your only resource, and they should be the ones servicing this.

When starting from scratch I would use an install DSP such as Ashly 24.24, QSC Q-Sys, or a dedicated FSR room combining system. Commercial systems need to be reliable, repeatable, scalable, and serviceable.
Yeah, I use symetrix or rane for these typically, client is nickle-and-diming me.  Walking away seems like the best course of action.
Title: Re: "Manual" room combining without DSP
Post by: Craig Hauber on February 11, 2016, 02:20:29 pm
It's those old Toa 900-series preamps, but the combining is just DIY radio shack toggle switches mounted to a panel.  Somehow those switches run in-line with the preamp output for each zone i think, and flipping them effectively combines the zones.  Does that make any sense?
I'm not on-site, all i have to go on are some pictures of the front of the rack.. i don't know whats going on behind it.

I've done a few where it's quite simple but accomplished using the 70V outputs instead of messing with the inputs. 
Each room's amp is large enough to drive all rooms and using rotary switches you just assign the room's speakers to whatever amp is being used.
I'm sure you could re-arrange things so that you are switching the amplifier's inputs to whatever pre-amp is active

I've also seen atlas/toa/bogen paging amps with the "mix/buss" rca on the back joined or "y"-connected using switches -this allowed all pre-amps to remain active so any inputs within the combined space are still useable.

But I've never actually seen a manufactured product for these purposes, always a kludge of homemade stuff that your lucky if it's even on a non-wood real rack-panel :-)

The Ashly 24.24 mentioned earlier or their PEMA amplifiers work great for this -with proper filtering, EQ and limiting that you just can't achieve with paging amps and switches!

If I recall, RDL made some modular bits that could be arranged into fairly robust room combining setups for lower cost than the DSP method -if you're stuck with what you have and no budget.
Title: Re: "Manual" room combining without DSP
Post by: Jason Lavoie on February 12, 2016, 09:34:32 am
It's those old Toa 900-series preamps, but the combining is just DIY radio shack toggle switches mounted to a panel.  Somehow those switches run in-line with the preamp output for each zone i think, and flipping them effectively combines the zones.  Does that make any sense?
I'm not on-site, all i have to go on are some pictures of the front of the rack.. i don't know whats going on behind it.

The TOA 900 series has a "bridge in/out" RCA connector. connecting these between amps creates an all inputs to all outputs scenario, so all you have to do is break the links with a toggle switch to separate the rooms.

It sounds like you're diagnosing something already existing, so I'll take a guess that someone may have moved the wires to the preamp out jacks and it doesn't work anymore

Jason
Title: Re: "Manual" room combining without DSP
Post by: duane massey on March 02, 2016, 10:56:17 pm
Back in the day (pre-dsp) I built a number of systems like this. Certainly not rocket surgery, but also very limited and unsophisticated. Drawing a simple one-line might help it make sense.