TOPIC:

Hi there folks.
I own a 4-way PA system (with) 2 channels passively crossed over) and I am looking to add some more subs of a different brand to the system. So I would like to have the processing power for 8 separate analogue outs with Dirac capabilities on each channel (something like the DDRC88A with BM would be ideal). However I already own the following equipment and I'm after some guidance as to if this can be incorporated into the system in any way to help achieve this result without having to shell out for the DDRC88A.
I currently own: 2 x mindsp 2 x 4HD (one is upgraded to a DDRC24) and a 4 x 10HD.

Also, with the DDRC88A, is there a way to go digital in to this device? Ideally I'd like something with the I/O capabilities of the 4 x 10HD but with Dirac Live capabilities on each output.

Any assistance here would be greatly appreciated!
Cheers
Andrew

Are you sure you need Dirac LIve on every output channel? Perhaps you could draw a diagram?

FYI there is a digital I/O version of the DDRC-88, the DDRC-88D - www.minidsp.com/products/dirac-series/ddrc-88d

As correctly suggested by John, you don't need Dirac live per channel. That's not how Dirac work. It corrects an overall speaker as per here:
www.minidsp.com/applications/digital-cro...akers-with-ddrc-88bm

You already have everything you do what you need I think. aka DDRC-24 (doing Dirac on L&R) => miniDSP 4x10 (doing crossover)

More than 2 channels of Dirac would certainly be nice.

My PA consist of multiple different speakers (A pair each of: F1 res2, RCF art 500, EV MTL2 manifold sub and a home made 6th order band pass sub cabinet). It actually sounds surprisingly good as is, however multiple Dirac channels would allow for phase alignment between the different cabinets, although I understand that it has its limitations with low frequency manipulation due to the added latency.

Yes I'm aware of the DDRC-88D. That would require the addition of 8 channels DAC as well and not be a cheap option.

The C-DSP8x12DL actually looks like it would have all of the features I'm after, but going back to unbalanced connections seems like a big step backwards!

moonthehoon wrote:

More than 2 channels of Dirac would certainly be nice.

My PA consist of multiple different speakers (A pair each of: F1 res2, RCF art 500, EV MTL2 manifold sub and a home made 6th order band pass sub cabinet). It actually sounds surprisingly good as is, however multiple Dirac channels would allow for phase alignment between the different cabinets, although I understand that it has its limitations with low frequency manipulation due to the added latency.

Yes I'm aware of the DDRC-88D. That would require the addition of 8 channels DAC as well and not be a cheap option.

The C-DSP8x12DL actually looks like it would have all of the features I'm after, but going back to unbalanced connections seems like a big step backwards!

I think you're misunderstanding Dirac Live's capability in 2-channel setups like your own. Dirac does not perform time alignment between different drivers, or main speakers and subwoofers. Time alignment needs to be configured separately in the plugin first, and then Dirac can be run on the combined (full-range) loudspeaker, or main speaker and subwoofer combination.

I am familiar with the process of time aligning drivers using REW and a UMIK-1 to measure the relative delays, and that is what I do prior to running Dirac live on the full system.

That is why I said "multiple Dirac channels would allow for PHASE alignment between the different cabinets" meaning any discrepancies in phase that could exist between two different speakers (that are time aligned as best possible) but due to perhaps output from say differently tuned ports may have some phasing issues going on.

[To clarify, here I am talking about two different cabinets on the same channel running the same signal and covering the same frequencies. i.e. not two cabinets that only share the same frequencies only at the crossover point]

Please correct me if I am wrong but isn't the real beauty about FIR filtering (and Dirac) the ability to manipulate the time domain independently to frequency? And isn't the application that I have just described one of the intended applications of multiple channel Dirac? If not, then what is the intended application for the DDRC88A/D?

I think there's just some confusion with terminology - you said "4-way PA system" which to most of us means two speakers that have four "ways"/drivers per cabinet (or three "ways"/drivers per cabinet plus subs). However you mean you have four separate speakers (correct?). A diagram would help.

Correct. I have the 4 cabinets (mentioned above) per side. You could think of it as a 4-way system (3-way + sub) sitting next to a 3 way system (2-way + sub) but the top frequency divider on each system is passive so I am really sending it 5 active signals 3 chanels to 4-way system and 2 chanels to 3-way system.

I'm currently using a DDRC-24 and 4x10 HD to get the 10 chanels

moonthehoon wrote:

I am familiar with the process of time aligning drivers using REW and a UMIK-1 to measure the relative delays, and that is what I do prior to running Dirac live on the full system.

That is why I said "multiple Dirac channels would allow for PHASE alignment between the different cabinets" meaning any discrepancies in phase that could exist between two different speakers (that are time aligned as best possible) but due to perhaps output from say differently tuned ports may have some phasing issues going on.

I use phase plots to optimise alignment between my main speakers and subwoofer, which is superior to just trying to look at arrival times. I still use this to set the time delays prior to running Dirac. I'd thought this was what you meant originally.

moonthehoon wrote:

[To clarify, here I am talking about two different cabinets on the same channel running the same signal and covering the same frequencies. i.e. not two cabinets that only share the same frequencies only at the crossover point]

This however was not I understood from your first post. If your whole system is effectively two pairs of full-range speakers (each formed by two boxes) then part of the question here would have to be what are you trying to achieve by doing this? Conventionally multiple subwoofers makes sense but more that two full-range speakers does not for stereo playback.

Actually what is the use case here? You refer to it being a 'PA system' - is this for sound for a venue with lots of people or a more conventional domestic setup with sound geared towards a single listener or a small number of people sitting on a sofa? Dirac is designed for the typical domestic case but not the former.

Used mostly outdoors for larger crowds and for a small number of folk on the couch when it's not at a gig.
I get your point about a point source being preferable for stereo imaging. Outdoors I use the F1 res 2s to throw the sound straight back and the RCFs turned in to fill the front centre listening position.

I've never used phase plots before. I'll take a look next time I have an opportunity

moonthehoon wrote:

Used mostly outdoors for larger crowds and for a small number of folk on the couch when it's not at a gig.
I get your point about a point source being preferable for stereo imaging. Outdoors I use the F1 res 2s to throw the sound straight back and the RCFs turned in to fill the front centre listening position.

Outdoor sound like that is not an area I have any real knowledge of but multiple speakers makes. I really don't think you want to be paying for Dirac though, for three reasons:

1. Dirac is designed for in-room correction, with a major point of it dealing with the effects of reflections from room boundaries that won't exist outside.
2. You aren't trying to optimise the sound over a relatively small area
3. You have two full-range speakers per channel rather than one.

Ok well thanks for your advice Ultrasonic (and others).

I will definitely take a look at phase plots next time I do a time alignment.

Cheers
Andrew