NAV-TV ZEN-M NTV-KIT871 MOST150 Audio Interface (2015+)
For Sale
Someone is selling the "Approved By HELIX" stamped versions on Ebay for $1010 + $136 shipping

https://www.ebay.com/itm/HELIX-Most-...V/264916522346

Someone is selling the "Approved By HELIX" stamped versions on Ebay for $1010 + $136 shipping

https://www.ebay.com/itm/HELIX-Most-...V/264916522346
So mine DOES have the mic and aux input ports there. I just don't have the harness or pinouts for what it does exactly.
It looks like the new helix manual shows 7 dip switches. That might be the difference in the newer models. They may have streamlined it for the Zen V and Zen M units.
Version 2.0 - Center will play audio in movie mode - like you mentioned dip 5 needed to be set to decrease the volume for phone call audio
Verrsion 1.2.7 (1.2.10) - Center channel plays audio during a movie, similar to above. However, phone audio is correct on 1.2.10, no dip change required.
Both will allow me to adjust phone volume once during a call, it's just that initial power on after unplugging the unit it's LOUD. Seems to stay low after you set it once. It's just that regular 1.2.7 and 2.0 that gain is turned way up, so the potential is there to get way louder.
Channel 9-10 does not play anything in movie mode, but does play audio in music mode. However, 1-6 play front audio, 7-8 play surround audio. 11 plays Center, 12 plays LFE. The dip switch settings that are mentioned are correct. There is a slightly noticeable change in audio for the for TOSLINK downmix setting, but it does play full range audio in both settings. I'm assuming this is just the mixing of the center into the front channel speakers. However, I would consider just using all RCAs just to feed the DSP in case there's any audio latency or differences due to D/A conversion.
That's pretty crazy that this car can play full 5.1 sound lol. Learned something new. I just won't ever use it, but it's nice to know I can use AC3 encoded audio.
To be honest, the way I have my car setup, even in 2.1 it sounds surround. I am delaying the rear deck speakers to kind of create this dolby pro logic surround feel, more for spatial/ambient/room effects.
So mine DOES have the mic and aux input ports there. I just don't have the harness or pinouts for what it does exactly.
It looks like the new helix manual shows 7 dip switches. That might be the difference in the newer models. They may have streamlined it for the Zen V and Zen M units.
Version 2.0 - Center will play audio in movie mode - like you mentioned dip 5 needed to be set to decrease the volume for phone call audio
Verrsion 1.2.7 (1.2.10) - Center channel plays audio during a movie, similar to above. However, phone audio is correct on 1.2.10, no dip change required.
Both will allow me to adjust phone volume once during a call, it's just that initial power on after unplugging the unit it's LOUD. Seems to stay low after you set it once. It's just that regular 1.2.7 and 2.0 that gain is turned way up, so the potential is there to get way louder.
Channel 9-10 does not play anything in movie mode, but does play audio in music mode. However, 1-6 play front audio, 7-8 play surround audio. 11 plays Center, 12 plays LFE. The dip switch settings that are mentioned are correct. There is a slightly noticeable change in audio for the for TOSLINK downmix setting, but it does play full range audio in both settings. I'm assuming this is just the mixing of the center into the front channel speakers. However, I would consider just using all RCAs just to feed the DSP in case there's any audio latency or differences due to D/A conversion.
That's pretty crazy that this car can play full 5.1 sound lol. Learned something new. I just won't ever use it, but it's nice to know I can use AC3 encoded audio.
To be honest, the way I have my car setup, even in 2.1 it sounds surround. I am delaying the rear deck speakers to kind of create this dolby pro logic surround feel, more for spatial/ambient/room effects.

Additional things you should know and I am not sure how this affects the zen-m output.
With the factory system, if you turn surround off in the radio the rear deck speakers provide no audio. The front center channel also reverses phase.
I am not sure what you mean by movie mode because with dip 3 up or down, both 2 channel music and 5.1/7.1 movie output will change in both toslink and RCAs.
Check the helix chart on page 17.
Also, I just realized if the toslink worked as expected you wouldn't need RCAs at all unless you wanted fading and true surround audio. The helix manual says on page 17 that with the toslink downmix enabled it should provide a fulrange stereo signal for dolby and dts coded signals.
If you had that working then you could feed front and rear the same audio and still enjoy your music and movies since the center is mixed in, all on toslink only.
Last edited by benzdude; Nov 22, 2020 at 09:38 PM.

Additional things you should know and I am not sure how this affects the zen-m output.
With the factory system, if you turn surround off in the radio the rear deck speakers provide no audio. The front center channel also reverses phase.
I am not sure what you mean by movie mode because with dip 3 up or down, both 2 channel music and 5.1/7.1 movie output will change in both toslink and RCAs.
Check the helix chart on page 17.
Also, I just realized if the toslink worked as expected you wouldn't need RCAs at all unless you wanted fading and true surround audio. The helix manual says on page 17 that with the toslink downmix enabled it should provide a fulrange stereo signal for dolby and dts coded signals.
If you had that working then you could feed front and rear the same audio and still enjoy your music and movies since the center is mixed in, all on toslink only.
The center channel only works during movies, not music. is what I mean. The rear deck speakers, I was thinking it would work as rear surround, but it's actually the rear door speakers. I did enable and disable the surround setting. There was a change in what seemed to be the front speaker audio, but I don't think it did anything for the rear deck speakers during music. The nav-tv appeared to just output another set of stereo audio for the rear channels (turned off if you faded up front).
Correct, It doesn't sound like there's anything missing if you have downmix turned on. I was just thinking it might do a mix for the center channel if you had it disabled (pulling out the vocals from L+R).
I've just left the unit at v2.0 since it doesn't seem like there's a reason to go back to the previous version.
I do feel like there's a lot of undocumented setup with navtv, but audiofischer did shine a bit more light on a couple of the features.
One thing I DID notice was that enabling surround mode with my current DSP settings over TOSLINK was that my stage shifted RIGHT, which I thought was very interesting. Perhaps this is the consequence of the front center being out of phase
The Best of Mercedes & AMG
posted up! Of course, outside of ebay is preferred due to fees, but I get the idea of buyer/seller protection and have put the starting price to help offset some of the added cost. I did leave best offers turned on though.
My intended upgrade piece isn't working the way it's supposed to, so I'm currently flipping back and forth, but will sell if a buyer wants it.

While I appreciate all of your generous testing and information, I always prefer to use Ebay and Paypal for my personal protection.
if I could guarantee (100%) that all features of this USED device would work as expected and nothing was broken, I would gladly pay you the full $700.
Thanks again for your time.

While I appreciate all of your generous testing and information, I always prefer to use Ebay and Paypal for my personal protection.
if I could guarantee (100%) that all features of this USED device would work as expected and nothing was broken, I would gladly pay you the full $700.
Thanks again for your time.
Also, ebay would have charged you tax on top.. so you would have paid even more (thanks california)... Not sure why you'd want to deal with that.
You see, this is why I don't necessarily like using ebay, unless it's the last resort and I need the audience for something I'm selling.
I'd say 10 years ago, it was great... but they've been trying to nickel and dime. I also refuse to give them my SSN and bank account for their new payment services. I just feel like that's a huge security risk waiting to happen.







