1 (edited by Keith_W 2018-04-03 12:19:26)

Topic: Measuring different convolution engines with Totalmix

Hello guys, please excuse my ignorance. I do not have a background in pro audio. I am a consumer audio hobbyist. I bought a RME Fireface UC to help implement my 8 channel home stereo.

Background of my problem: I am running a pair of four way speakers in stereo. I generate crossover filters using Acourate, then use a convolution engine to send 8 channels of digital into an 8 channel DAC. From there, it goes to 8 channels of power amplification, and then to each driver.

Subjectively, the convolution engines I am using (HQPlayer and Acourate Convolver) sound different even though they are running the same filters. They continue to sound different even after being level matched with a handheld SPL meter.

I want to measure the output of HQPlayer and compare it to Acourate Convolver, preferably before the signal undergoes DA conversion to find out if I am imagining things or it is real.

What I want to know is: how do I do this.

1. I will be using Room EQ Wizard (REW) to generate the log sweeps and to take the measurements. Setup of REW seems simple enough. All I need to do is run a pre-recorded sweep through each convolution engine using this procedure: https://www.avnirvana.com/threads/can-r … #post-6391

2. The main issue is that both convolution engines will be using the SAME ASIO output that REW will be using for its input. I don't know enough about RME Totalmix to know how to configure it to make this possible.

The relevant section in the manual (on page 71) says:

[*]"Recording a Software's playback
In real world application, recording a software's output with another software will show the following problem: The record software tries to open the same playback channel as the playback software (already active), or the playback one has already opened the input channel which should be used by the record software.

This problem can easily be solved. First make sure that all rules for proper multi-client operation are met (not using the same record/playback channels in both programs). Then route the playback signal via TotalMix to a hardware output in the range of the record software, and activate Loopback for recording."[/*]

The section I have highlighted in italics is giving me problems. How exactly do I do this? What I want to do is:

Convolution engine --> RME Totalmix --> REW for recording

At present this is how the RME is set up:

Digital input 1: Left subwoofer
Digital input 2: Right subwoofer
Digital input 3: Left woofer
Digital input 4: Right woofer
Digital input 5: Left mid
Digital input 6: Right mid
Digital input 7: Left tweeter
Digital input 8: Right tweeter
Microphone input: Microphone (Earthworks M30)

I presume that I need to repeat the procedure 8 times for each channel, each time routing one of the digital inputs into the mic input?

Re: Measuring different convolution engines with Totalmix

If REW permits you, instead for compare noise (or know signal) versus live/recorded signal, compare one signal versus the other one. We use here SMAART v8 which is multi-input and using RME interfaces you can loop audio from an audio host for playback (REAPER or Samplitude for example.)

Saludos, Enrique

Saludos Enrique.