Mid Side M-S Matrix Uses No Precision Resistors

[emrr]

Thanks for the report. I've been messing with the software version of this in DP for various mastering processes, and found that starting at -6 is a given with everything I've tried. I admit to missing that detail in previous readings here, and it's definitely proven to be a brick wall one must navigate.

[mediatechnology]

I also tried the precision bypass mode and the crosstalk improved. I swapped the L&R channels from prior measurements. By hand picking 1246/1240 combinations I can make the L to R as good as the R to L numbers. Unfortunately on this prototype the left channel 1246 is soldered to a flying lead. The "worst" case however is still better than - 70 dB.



The right channel at -90 dB is pretty good. The rising characteristic of the crosstalk beginning at 2 kHz occurs in the soundcard and leads.

I also double-checked the encoder headroom with mono input. If the encoder balanced output is de-balanced to single-ended, by grounding the 1646's output, the input headroom becomes approx. +17 dBu. The 1646 adds 6 dB of gain and clips at ~+23 dBu single-ended (18V). This reduces the input headroom by 6 dB. When the 1646 outputs are fully-balanced however there is 6 dB of added headroom.

[mediatechnology]

I ordered new prototype boards yesterday which should be here Friday. Thanks for updating the layout Roger!

[mediatechnology]

I had a chance to build the latest version with the added 1240 in the decoder. It works great.



This particular board is wired for single ended L&R inputs and outputs. The jumpers can be seen on the left-hand and right-hand side of the board. The insert connection, in the middle of the photo is fully balanced.

I'll be posting crosstalk figures soon.

[emrr]

Lookin' good!

[Mastertone]

Great stuff Wayne!

Can wait to put a few of these in my console.

[mediatechnology]

Thanks guys. I need to run a few more tests and then I'll order us some boards with silkscreen and solder mask.

[Gold]

Great news. I'm in for eight.

[mediatechnology]

Wow. Thanks Paul.

[flaheu]

Cool, I was regularly lurking to this thread.
I'm always impressed by the quantity of work you guys can do
If some pcb's are coming, I'm in for 2.

Cheers