External sound sweep source

[Tony Walters]

HI, my amplifier setup is front-ended with a dedicated music server running Volumio, then to a dual I2S DAC, one feeding the sub directly and the other feeding the L&R amplifier. The amplifier does not have a crossover built in, thus requiring this particular setup. So I am unable to connect my laptop running REQ to the amplifier as that leaves out the sub. The DSP filters, including the mains/sub crossover, are configurable within the DACs. The music server and the DACs do not have RCA or mini jack inputs, so I must either play the sound sweep from a file stored on the server, or play wirelessly form my laptop using Airplay or uPNP. Playing the sweep from a file on the server results in not being able to synchronise with the REQ sweep recording, resulting in corrupted data. When I play over the network by streaming the REQ output, there is a delay of several seconds before the sound plays, again confusing REQ and corrupting data. By tuning the network I can get the delay down to a half second or so but still data gets corrupted. Is there a way to decouple the REQ sound output from the input, yet still synchonise the process? Any other suggestions. I have been working on a home project that will automate the instantiation of REQ filter file to the DSPs, and also wouls like to create a DSP entry in REQ. The user interface cost for Volumio has been built which allows the user to select from a list of profiles e.g. Room Couch, Room Back, Dance etc., in order to set the DSP operation. One possible solution might be to be able to set an "external source" mode, where the REQ sweep is played externally. When the REQ software is able to detect a frequency, it then starts its measurement to match from that point on. This issue with the sound synchronization was an unexpected impediment.
Thanks in advance for any assistance in this situation.

 

[AudiocRaver]

I believe the answer is that John is working toward the capability you request, but that for now, one must manually perform the synchronization.

You can create/record a sweep with the REW generator with the acoustical timing chirp at the beginning, then play that back from your server through your system and listen for the chirp and use that as your "trigger" to start the analysis.

 

[John Mulcahy]

Easiest is to generate the sweep with a timing reference (as described in "Generating the sweep signal" here) and tick the "Wait for timing reference" box on the Measure dialog.

 

[AudiocRaver]

Ah yes, Thanks John. That will do it!

 

[Tony Walters]

Thank you both - worked like a charm.

Using Allo Piano card with built-in DSP. Will be moving over filter parameters for use in combination with Volumio player. We have built the UI code for Volumio to select from a drop-down list of room configurations such as couch, dancing area etc. which will configure the board. All good fun!