Room correction and DSP via widely available recording mixer devices?

[Jagged24]

I've seen a lot on HFW and other forums about dedicated (and fairly expensive) components that incorporate ADC/DSP/DAC devices to enable room correction and frequency equalization from both analogue and digital inputs in a 2-channel audio system. I refer, for example, to the DSPeaker Anti-Mode or similar.

Could similar functions be performed using widely available mixer control devices used by musicians for recording?

Companies like Focusrite or RME make relatively inexpensive components that have multiple analogue / digital inputs for audio sources, condenser mic inputs with phantom power to monitor room frequencies, and virtual 'loops' for DSP and equalisation using bundled software on any Mac or Windows computer. The ADC / DSP / DAC devices these components use appear to be very very well specified (sampling 24 bit/96 kHz or more, and excellent SNR specs). Prices seem very reasonable (~£125 - >£500)

Has anyone gone used these (or similar devices) in 2 channel systems ? Or are there reasons why this wouldn't work?

 

[speedysteve]

I will be interesting to see what responses you get.

My own attempts at using PA / Pro audio stuff with Behringer DCX 2496's resulted in low res sound even when some of the mods others raved about were tried.

Coco took them further with transformer output stages (pretty complex) and digi in.

All of this was easily beaten by a DIYaudio designed Najda (design remit to be better than miniDSP's stuff) and probably as good as the very expensive DEQX offering.

I and Coco use these for X/O work and some correction. I replaced Antimode 1.0's on my tapped horn subs using the correction that is available in Najda and it's much more configurable than a one hit measures and corrects what it can system like Antimode.

I do a little cutting only correction on the mid bass and nothing on the other channels - that's how it sounds best. Coco does some correction on his RCA field coil drives that are working as mid range drivers- not sure if he does more? Would guess so.

It depends how handy you are, how much measuring and how many listening tests you are prepared to do.

In a high end system I would say you will struggle with the Pro audio stuff with gain structures (input and output levels), and ultimately sound quality in a hifi system. But as said be very interested to hear from others who get it to work.

 

[Jagged24]

Thanks Steve, that is very helpful. I looked up your/Coco's DIY thread about the Najda DSP - looks like an excellent project, and does all the functions I would be looking for (ADC, DSP including equalization and room correction, and DAC).

Why do you think the Pro audio stuff might have different gain structures than 2 channel audio? I looked up the specs for the RME Babyface (http://www.rme-audio.de/en_products_babyface.php) or Focusrite USB units (http://uk.focusrite.com/usb-audio-interfaces) and didn't see any problems.

As Steve says - it would be very interesting to hear from anyone else who has tried components of this kind in a 2 channel audio system!

 

[speedysteve]

Gain structure problems were apparent with the Behringer 2496, it expects much higher input voltages than our hifi CDP's or preamps can muster so the noise floor is all wrong, and needs serious attenuation of the output signal which is far to high for our tender power amps... I assume all pro gear is the same. Lots of info here.

http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.htmll

Najda was designed for hifi, same as miniDSP and DEQX

 

[AmDismal]

Sure, I use a Lynx card (AES16) so my computer can be a 5-way crossover with some DSP as well.

if you don't need the XO, you can do it all in the PC with no fancy soundcard - just get Reaper or J River to do the DSP (both do eq and convolution) and output to your Audiolab. For your TT, get a decent A-D and you're there. However, many find that the routing can be a pain (strong hint - use one of the software packages mentioned above), hence the attraction of the Najda.

i set up a PC system for Heyward on here, must check how he's getting on with plugging the TT into it...

 

[Jagged24]

Thanks Steve. The link you provided "Lots of info here.

http://www.diyaudio.com/forums/diyau...structure.htmll" is terrific - lots of food for thought there about the gain structure of ordinary 2-channel systems that I had not previously appreciated.

Very helpful Adam. Can you recommend an ADC for the TT / phonostage input? I assume the ADC will require a line level signal that has been RIAA equalized ..... but out of curiosity, would the signal be cleaner if an MM cart output was ADC'd first followed by RIAA and preamplification in the digital domain?