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Discussion Starter #1 (Edited)
Goal: Mix the 'low level' mono NAV & Phone voices from my OE HU with the mono Upmixed Center output from an MS-8 DSP to one channel which will be fed to the input of an MS-A1004 amp, driving the center speaker.

Vehicle: 2019 Honda Ridgeline RTL-E with an OE amp/DSP module separate from the 'HU' (Audio/NAV Module). The plan is to feed only the full-spectrum rear speaker-level outputs from the OE amp/DSP to the MS-8 (all other OE amp/DSP outputs will be abandoned / not used); those rear channels do not carry any vehicle / non-music tones or voices. The MS-8 will drive 2-way front, front center, rear ambient fill, and sub, all through JBL MS-Axxxx amps (I already have all the JBL components from a previous install).
  • At this time I know the NAV and Phone output from the HU to the OE amp/DSP are 'low level analog signals' but I do not know their actual voltage range. I propose to 'tap' but not 'cut' those signals between the HU and OE amp/DSP.
  • We know that the MS-8 low-level output ranges from 0-2.8V max.
  • We know that the MS-8 output will always be silent when the NAV or Phone Voices occur (the OE amp/DSP automatically MUTES the rear channels connected to the MS-8 when those voices occur, so there will be no audible output on any MS-8 Channel when NAV or Phone Voices occur)
  • We know that the NAV and Phone voices can occur concurrently.
The passive mixer of interest is the Rolls MX42 Stereo Mini Mixer, widely available for ~$50:
The "Manual" for the mixer, with 'specs', is attached below as a PDF.

Here's a diagram of the scheme superimposed on the Mixer Schematic:


Would this scheme "work" to achieve what I want? If 'maybe yes' please continue ...
  • When the MS-8 output is active, would the Mixer Output voltage be significantly lower than the MS-8 Input voltage?
  • Would this likely be a 'noisy' device in my audio chain?
  • Are there other downsides that this admittedly 'electronics circuit ignorant' person should be aware of?
  • Any / all other comments / suggestions most welcome.
I'm fairly certain that I can achieve my goal using an active miniDSP between the MS-8 and the amp as the signal mixer (letting MS-8 'correct' for the additional processing delay during setup / calibration); just wondering if this lower-cost and simpler passive idea has any merit?

THANKS in Advance for any feedback!


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