Is anyone using a ULN8 as an active crossover ?

[sdevino]

There are Linkwitz-Riley filters implemented in as crossovers (part of the bandsplit primitive) in the primitives. You can easily build your own custom crossover including any number of band splits etc.

 

I use my ULN8 for deriving LR, LCR, Dolby 5.1 with and without crossovers depending on the speakers I am using.

 

Steve

 

 

 

[sdevino]

Thanks Barry. I am looking forward to learning what I can.

 

Steve

 

[sdevino]

Here is a link to all the DSP plugins which we have been referring to as primitives up to now. Unfortunately it doesn't seem to include some of the newer plugins including the band split.

 

http://www.mhsecure.com/technotes/v5MixerOverview/MIO+DSP_Plugin_Index/index.html

 

Happy Reading!

 

Steve

 

[sdevino]

The DEQX looks pretty interesting and probably would be a little more turn-key than the MH unit. It would be interesting to compare sound quality sometime though.

 

But I really wanted to comment on physical verse electronic room compensation. One advantage of physical room compensation is that it generally focuses on things like diffusion and bass trapping which are beneficial to the entire listening space (in general).

 

Electronic room compensation is usually only valid at the measurement point. To be effective beyond a single sweet spot the analysis needs to be done for all critical listening areas and then the best set of trade offs would be made. This is where a ULN8 can be advantageous. With 8 input channels the user can measure at 8 locations simultaneously and use MH DSP primitives such as band split and all pass filters and delays to make time based adjustments while using the transfer function of Spectra Foo to see full spectrum realtime phase and power response on all channels.

 

Electronic speaker/crossover compensation can of course be very effective as long as the speaker is measured in a well managed acoustic environment that considers the design of the driver.

 

Steve

 

[sdevino]

Its hard to argue with the advantages of the Deqx for speaker compensation, but one of the primary objectives for the original Metric Halo 2882 was multi-zone measurement for Spectra Foo. The 2882 and now the ULN8 are commonly used for large room (professional theatre) measurement because of the ability to compare multiple parts of the room.

 

That id meant to imply that it is better than the Deqx but it is a primary purpose for the tool. I think which is best depends somewhat on what you are doing and what your comfort level is with various tools. I like spectra Foo because I can clearly see what it is measuring and make my own decisions. Obviously the MH interfaces are better for Spectra Foo.

 

I imagine the Deqx would be far more convenient for speaker alignment.

 

Barry, I agree with your comment. So far I much prefer gear that needs no alignment, and I rarely if ever recall a cal procedure actually improving what was already a good design.

 

Steve

 

 

 

[sdevino]

Hi Barry,

FYI the Apple Remote support for the ULN8 was disabled during the beta cycle. It worked great so I hope it makes a reappearance someday.

 

Steve

 

[sdevino]

The ULN8 supported the use of the Apple Remote during the beta stage. For various reasons that capability was withdrawn prior to release. I am under NDA so I will not discuss this in further detail.

 

That being said, Since my shuttle Express is the primary control I use for operating the ULN8's analog console volume it should be possible to use any device or application which provides detectable key commands.

 

The key sequence for volume control is "cmd-opt-ctrl-" followed by up or down arrow.

 

I would test my remote with Amarra but I decided not to purchase a license after my demo ended.

 

Steve

 

[sdevino]

I think many pros (in my case I am a sound designer for theatre) actually develop speaker correction separately from room correction. Speakers are typically measured offline in some type of near anechoic environment (such as outside). In live settings room corrections are usually focused on time alignment from multiple sources (i.e. aligning arrival from the fill speaker with arrival from the center cluster or line array.

 

Room issues are managed by speaker selection and focus by selecting the most appropriate coverage for a given space requirement. The idea is to keep the sound off the walls and on the audience. Minor EQ can be done but I mostly focus on using EQ to avoid bass build up caused by having multiple directional speakers in a given area all of which are omnidirectional at lower frequencies.

 

Lastly for high end active speakers such as Meyer, d&B, ADR Audio and others, the speaker comes with built in DSP compensation for driver and crossover alignment. It is very hard to improve on what these manufacturers provide.

 

Just my perspective which is probably different than the typical live rock show provider.

 

Steve

 

[sdevino]

Pretty much, plus we don't really compensate for the room as much as we try to avoid the room wherever possible by managing bass and covering small areas with low power as needed (in areas uncovered by the mains).

 

Steve

 

[sdevino]

All the Metric Halo plugins run in the DSP chip on board the interface so there is no way to integrate AU or VST plugins. However, Metric Halo provides a plugin for AU, VST and RTAS formats which will embed the configuration (all DSP plugin and routing) information in the host program.

 

So any DAW that runs on a MAc can use its plugin capability to provide custom total recall of any MIO configuration.

 

In addition each MIO has 18 firewire sends to the DAW and 18 DAW returns via the firewire i/o. So there is no reason that you cannot integrate host based plugins with MIO based DSP. In fact many of us in the live sound community use this very configuration to integrate CPU intensive IR plugins and long delays with our MIO based mixers.

 

Steve

 

[sdevino]

I use Mainstage, GR4 or Logic. But that is mainly for live performance. You can use any DAW that supports AU or VST.

 

Steve

 

[sdevino]

You raise a good point but the Metric Halo units do pretty well in this type of app. First off the routing and DSP setup in the Metric Halo DSP is persistent and can be stored as a default boot state. So if your Metric Halo mixer routed DAW1&2 to your EQ and then to your monitoring system you would be all set to go with itunes on launch or restart. If iTunes were your only app then you could put iTunes on your startup list as well.

 

If you also needed a secondary CPU based process to run, you could store the process document in your startup folder and have it launch correctly figured. If it were also an AU host it could launch and configure the Metric Halo DSP as well.

 

This is simply a matter of saving your host document with the Console COnnect AU plugin loaded with the Metric Halo routing set as you like it.

 

So it might not be as bad as you think.

 

Steve

 

[sdevino]

Just a clarification. While the knob on the front panel of the ULN8 is a digital encoder as Barry pointed out, it is actually controlling an analog level process. Put another way the audio is in the analog domain when the playback volume is adjusted. It is not done in the digital domain.

 

Steve

 

[sdevino]

I just implemented a 2.1 electronic crossover with both Turntable and DAW inputs plus an RIAA curve at 24/192 on my ULN8. So I am not sure what you ran into.

 

I did use 94% of my DSP capacity to do this but it does seem to work fine.

 

BTW at 96/24 it only uses 42%.

 

Steve

 

[sdevino]

If you email it to me I can tell you what it uses on a ULN8/LIO8.

 

Steve

 

[sdevino]

Just send it to sdevino at the gmail.

 

Steve

 

[sdevino]

Actually if he uses the band split math block in a graph he will have access to linkwitz-Riley filters. That's how I did it anyway.