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Using 2 identical amp racks for larger systems


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I'm trying to stream line things a little more, powering a JBL srx rig I use 1 rack dedicated for both stacks (1 over 1 or up to 3 over 2). The amp rack that does this has a cx502 on horns and 3 yamaha P7000 with a drive rack for processing.

 

I could buy another P7000 and use another cx502 and have 2x 8sp with a cx502 and 2x P7000s with a DRPA in each. I'd still wire them stereo in each but use an XLR Y or jumper between the XLR inputs on the panel (each panel has both XLR F and M so that either gender of XLR can be used to drive the inputs or used as a passive split).

 

Is the drpa accurate enough where if 2 drpas are set identically they will both output (sound) the same?

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Yes, every amp rack we have is standardized this way, the drs are plenty accurate. Also, programmed in stereo but using only one channel gives you the option of driving the second input with aux fed subs and just moving the sub output from ch 1 to ch 2.

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The amp racks I built for my SRX 725 over 728 rig is one P7000 over one RMX4050 HD in each rolling case, wired to a quad box.I have the DR+ at foh and a 12 send snake. I biamp that system. Nice to run short nl4 to the cabs.i roll with one rack for a half system. A bit underpowered on the tops

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Unalaska wrote:

I'm trying to stream line things a little more, powering a JBL srx rig I use 1 rack dedicated for both stacks (1 over 1 or up to 3 over 2). 

 

 


I am glad you asked this question as I have contemplated it as well.  I saw Aged's set up once, or at least part of it.  While I don't want to speak for him I believe one  important factor with his set up is he deploys speakers in blocks of 4 tops and 2 subs or something like that.  So on a give side he might have a small setup with 4 and 2 or a bigger setup with 8 and 4, pr 12 and 6, etc.  So a single amp rack would get way too unwieldy and it makes sense to unitize it.

I only have 4 tops and 8 subs total and, like you, all the amps fit in a reasonable size rack.  Even when only using 1/2 the system it is not a big deal to bring the whole rack.  Adding a second amp rack would be more stuff to schlep around.  The rack itself weighs as much as the amps and takes up 2x the space of one rack.

For me, I decided that running speaker wires themselves was the LEAST confusing thing in general.  I try a lot of different configurations and to some degree managing the DR260 configuration is the MOST confusing aspect.  So although I carry a spare with, hopefully, duplicate programs, I would rather just use the one DR260 for both left and right stacks.

Streamlining to me means having a repeatable set up and not having to think too much about the connections between the DR260 and the amps.  I have about 6 different DR260 program presets and select the one appropriate for the speaker configuration.  

A key component for being able to use the amps in a flexible manner without having to get into the back of the rack is making a patch panel for the rack that allows a few different types of connections.  In the picture below you can see there are two XLR inputs.  Depending on the DR260 program these are either L and R or aux subs and mains.  The  speakon connectors are setup with two per amp.  The amps run in stereo and the first speakon gets both amp channels 1 & 2  on 1+/1- and 2+/2- for a 4 conductor cable.  The second speakon gets only channel 2 on the speakon pins 1+/1- in case you want to run that channel separately on a 2 wire cable.

This arrangement keeps me out of the back of the amp rack unless I want to bridge an amp or something out of the ordinary (for me).  But in general I know exactly what to expect from each speakon output and that consistency has done more to streamline set up and prevent mistakes for me.

P.S. If I redo this rack I will probably put the patch panel on the bottom for a cleaner look.

amp-rack.jpg

 

 

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I recently expanded and decided to go this route as well; I run the same set of Crest amps in both and run 2 PA+ (aux sub & back-up) per rack. I have not seen any issues yet with balance from the PA+ units and I have the same tweaked (crossover tuning & limiter tweaks for both mains and aux subs) settings in all 4 boxes for ease of setup/back-up swap. 3 of the 4 are in a fairly close s/n range but like others said, don't think it is an issue for dbx meeting the consitency piece.

The only recommendation I have is that once you go this route, practice what you would do if something goes down, it is surprising how this relatively simple addition means you need to think a little broader....when I did this test, I realized I didn't have the same custom settings in all 4 PA+ units for both mains & aux sub duty and it also made me get some custom Y cables made to feed the amps in either rack from any of the 4 units if I had to (only a practical solution when I have the racks side by side).

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