2018 Globetrotter Main Cabin TV / Polk Audio Modification

[ddrg]

The main cabin Samsung TV supplied by Airstream in the 2018 Globetrotter has been modified to include left / right line out level audio connections, (derived from the TV internal speakers), which are connected to the AUX line in on the Polk audio system. Using this configuration, you will hear the TV speakers in addition to the Polk speakers.

I wanted to be able to independently control the Polk audio level from the TV speakers, including not hearing the TV speakers at all.

I purchased a "Prozor Digital to Analog Converter DAC Digital SPDIF Toslink to Analog Stereo Audio L/R Converter Adapter with Optical Cambe" for $12.95 from Amazon. The DAC includes a shorter optical cable as well as a USB power cable.
https://www.amazon.com/PROZOR-Digita...ords=spdif+dac

The attached picture shows the installed result.

Instructions:
1. Disconnect the AUX left / right RCA male connectors from the TV out left / right female connectors.
2. Attach the Prozor DAC to the back of the TV using double sided tape as shown.
3. Connect the Prozor left / right RCA female audio out connectors to the respective Polk AUX left / right input RCA male connectors.
4. Connect the TV SPDIF output to the Prozor SPDIF input using the supplied optical cable.
5. Remove the right angle connector from the HDMI cable going to the TV input.
6. Connect the Prozor DAC USB power cable to the TV USB port.
7. Wrap the cables as shown.

The DAC output level is fixed - use the Polk volume control. The TV speaker output will be independent from the Polk audio level using this configuration.

Ciao… Duncan

[Stillwater]

Thank you so much for posting this modification Duncan! We received the analog converter from Amazon today and installed it just like you showed above. What a huge improvement! It was driving us crazy that we couldn't hear the TV/Movies through the stereo system. Can't thank you enough for this inexpensive solution!!

[ddrg]

Originally Posted by Stillwater

Thank you so much for posting this modification Duncan! We received the analog converter from Amazon today and installed it just like you showed above. What a huge improvement! It was driving us crazy that we couldn't hear the TV/Movies through the stereo system. Can't thank you enough for this inexpensive solution!!

I'm happy that the modification worked out well for you :-)

Ciao... Duncan

[GOUSC]

We just picked up our new 2018 GT a week ago and during the demo I asked the tech to demonstrate the use of the Polk Audio system in coordination with the TV. We were able to use a) only the TV speakers b) only the Polk audio speakers, or c) both without modification. I'm interested in Duncan's comments if his modification does anything different than this (I'm assuming the only difference is he can operate any volume with the TV remote only).

To do this, turn on the Polk Audio unit, PA.

Press the Mode button on the PA twice until the AUX selection comes up as a mode. Press the button next to the AUX selection to activate the AUX mode and the PA surround speakers. The following selections have to be done while the PA is in the AUX mode.

To use only the PA speakers - turn the volume down on the TV with the TV remote and turn up the volume on the PA by turning the PA round Encoder Knob clockwise.

To use both the PA and TV speakers - turn the TV volume up with the TV remote and PA volume by turning the PA Encoder Knob clockwise .

To use only the TV speakers - turn down the PA volume by turning the PA Encoder Knob counter clockwise until the volume goes all the way down. Turn the TV volume up with the TV remote to the desired volume.

[ddrg]

Originally Posted by GOUSC

We just picked up our new 2018 GT a week ago and during the demo I asked the tech to demonstrate the use of the Polk Audio system in coordination with the TV. We were able to use a) only the TV speakers b) only the Polk audio speakers, or c) both without modification. I'm interested in Duncan's comments if his modification does anything different than this (I'm assuming the only difference is he can operate any volume with the TV remote only).

To do this, turn on the Polk Audio unit, PA.

Press the Mode button on the PA twice until the AUX selection comes up as a mode. Press the button next to the AUX selection to activate the AUX mode and the PA surround speakers. The following selections have to be done while the PA is in the AUX mode.

To use only the PA speakers - turn the volume down on the TV with the TV remote and turn up the volume on the PA by turning the PA round Encoder Knob clockwise.

To use both the PA and TV speakers - turn the TV volume up with the TV remote and PA volume by turning the PA Encoder Knob clockwise .

To use only the TV speakers - turn down the PA volume by turning the PA Encoder Knob counter clockwise until the volume goes all the way down. Turn the TV volume up with the TV remote to the desired volume.

Great to hear that Airstream has modified the way the audio system works on production systems. Our GT works the way I described, which is why I made the modification that I posted. I guess this is the price you pay to have the prototype unit. Having said that, I'm really pleased we do have the prototype, because it is the only unit with Firefly lighting / fan / environmental control :-)

[ddrg]

Originally Posted by ddrg

The main cabin Samsung TV supplied by Airstream in the 2018 Globetrotter has been modified to include left / right line out level audio connections, (derived from the TV internal speakers), which are connected to the AUX line in on the Polk audio system. Using this configuration, you will hear the TV speakers in addition to the Polk speakers.

I wanted to be able to independently control the Polk audio level from the TV speakers, including not hearing the TV speakers at all.

I purchased a "Prozor Digital to Analog Converter DAC Digital SPDIF Toslink to Analog Stereo Audio L/R Converter Adapter with Optical Cambe" for $12.95 from Amazon. The DAC includes a shorter optical cable as well as a USB power cable.
https://www.amazon.com/PROZOR-Digita...ords=spdif+dac

The attached picture shows the installed result.

Instructions:
1. Disconnect the AUX left / right RCA male connectors from the TV out left / right female connectors.
2. Attach the Prozor DAC to the back of the TV using double sided tape as shown.
3. Connect the Prozor left / right RCA female audio out connectors to the respective Polk AUX left / right input RCA male connectors.
4. Connect the TV SPDIF output to the Prozor SPDIF input using the supplied optical cable.
5. Remove the right angle connector from the HDMI cable going to the TV input.
6. Connect the Prozor DAC USB power cable to the TV USB port.
7. Wrap the cables as shown.

The DAC output level is fixed - use the Polk volume control. The TV speaker output will be independent from the Polk audio level using this configuration.

Ciao… Duncan

I should have noted in my original post that you need to set the tv optical output to PCM mode (rather than Dolby Digital Mode) for the DAC to work correctly. (Menu / Audio / ...)

[link2dks]

"Great to hear that Airstream has modified the way the audio system works on production systems. Our GT works the way I described, which is why I made the modification that I posted. I guess this is the price you pay to have the prototype unit"

Apparently they did not fix it. My 2019 GT, built in July of 2018 worked the same as yours. That is, the TV sound had to be on for the Polk Aux to get a signal for the cabin speakers. If the TV speakers are turned down but not off the Polk amplifier can amplify the sound enough to make it appear that the cabin speakers are the only ones on.

It would have been so much easier for Airstream to do what you did with the Digital Audio Converter (DAC.) Rather than going to the trouble of taking the back of the Samsung TV off to attach an RCA cable to the tv speaker wires to send an audio signal to the Polk, when there is an audio optical out on the back of the tv already.

Thanks for your simple to do and inexpensive (Amazon 12.99) fix to this problem.

https://www.amazon.com/PROZOR-Digita...ords=spdif+dac

Dave S

[ScottP]

Thank you for posting - all of you.

I’ll check if our 2019 GT has been set up by AS to accommodate the Polk speakers. If not, I’ll have an alternative option with detailed instructions from your post. Thanks

[stevejones]

Inspired by this thread I got the Prozor Digital to Analog Converter. The other half of the plan was to use a small Sony soundbar for the front speakers instead of the TV speakers. My intention was to drive the soundbar using the headphone output on the TV. Finally hooked it all up this afternoon and discovered three things.

1. The Prozor unit has a small amount of processing latency. This manifests itself in a small delay between the TV speakers and the Polk Audio speakers. This makes the system sound "reverby" to use my wife's expression. We did not like the effect.

2. When Airstream wired up the RCA plugs from the TV to drive the Polk unit, I do not believe they connected these to the speaker outputs as many think, I believe they sacrificed the headphone output. I found this out when I tried to drive the soundbar off the headphone output. Nada. No signal.

3. The last thing I discovered, was what I'll call channel swap. The left and right RCA plugs that are in the harness behind the TV lead to the Polk Audio Unit. The red plug, normally associated with right, goes to the right speaker if you are standing facing the speakers. That's how it comes hooked up from the factory. Makes sense if you are listening to music. But if you are watching TV, you are facing the opposite direction. So this means the right channel signal on the TV is now on your left side behind you, or over you, on the Polk system. This skews the stereo imaging of the sound field. So I have these flipped now to correct the stereo imaging.

Anyway I removed the Prozor unit and put it all back the way it was. I'd still like to use the soundbar but need a way to drive it.

Steve

[link2dks]

Originally Posted by stevejones

Inspired by this thread I got the Prozor Digital to Analog Converter. The other half of the plan was to use a small Sony soundbar for the front speakers instead of the TV speakers. My intention was to drive the soundbar using the headphone output on the TV. Finally hooked it all up this afternoon and discovered three things.

1. The Prozor unit has a small amount of processing latency. This manifests itself in a small delay between the TV speakers and the Polk Audio speakers. This makes the system sound "reverby" to use my wife's expression. We did not like the effect.

2. When Airstream wired up the RCA plugs from the TV to drive the Polk unit, I do not believe they connected these to the speaker outputs as many think, I believe they sacrificed the headphone output. I found this out when I tried to drive the soundbar off the headphone output. Nada. No signal.

3. The last thing I discovered, was what I'll call channel swap. The left and right RCA plugs that are in the harness behind the TV lead to the Polk Audio Unit. The red plug, normally associated with right, goes to the right speaker if you are standing facing the speakers. That's how it comes hooked up from the factory. Makes sense if you are listening to music. But if you are watching TV, you are facing the opposite direction. So this means the right channel signal on the TV is now on your left side behind you, or over you, on the Polk system. This skews the stereo imaging of the sound field. So I have these flipped now to correct the stereo imaging.

Anyway I removed the Prozor unit and put it all back the way it was. I'd still like to use the soundbar but need a way to drive it.

Steve

Steve

A couple of comments. First of all I'm no A/V expert. I haven't noticed the latency you mentioned b/c I have never used the TV speakers and the cabin speakers from the Polk at the same time. To me that was the point of doing the conversion with the DAC. Am I missing something?

Nice pick up on Airstream sacrificing the headphone jack, sounds (pun intended) right.

As far as stereo imaging I hear you I find the cabin arrangement particularly unsuitable for experiencing any degree of good stereo separation while watching the TV because you end up sitting directly under either the right or left overhead speaker the way the lounge is configured. I believe it was NYRN who disconnected his lounge speakers and installed down firing speakers in the same cabinet to improve sound quality with some improvement.

I agree with you that a sound bar is the only reasonable way to go for the best audio experience. I haven't gone this route because I've found that we rarely watch DVD's in the AS, so I haven't tried to try to install one. Would it not be possible to use the optical audio out on the TV as a source for a sound bar provided it had an optical input and its own power source?

Dave S

[Hiho Silver]

I agree with you that a sound bar is the only reasonable way to go for the best audio experience. I haven't gone this route because I've found that we rarely watch DVD's in the AS, so I haven't tried to try to install one. Would it not be possible to use the optical audio out on the TV as a source for a sound bar provided it had an optical input and its own power source?



Dave S[/QUOTE]


Yes, that’s what I did. Used the optical output for the sound bar. Only hassle is both TV and sound bar remotes needed to mute, as I recall.

[lsbrodsky]

Many soundbars have a "learn" from the TV remote...both of mine do. The soundbar is a huge, huge improvement. But, in my older Airstream, the TV they bought was the cheapest Samsung available with no outputs for anything. Their hack was to solder wires to the speaker wires for output to the SONY headunit. In the end, the only solution for me to get the various things I wanted, including an optical output, was to replace the TV with something newer. TV's that size are just not expensive.
Larry

[Mollysdad]

Originally Posted by stevejones

2. When Airstream wired up the RCA plugs from the TV to drive the Polk unit, I do not believe they connected these to the speaker outputs as many think, I believe they sacrificed the headphone output. I found this out when I tried to drive the soundbar off the headphone output. Nada. No signal.

Speakers should never be used to drive a line level input. So, in many units where there is no headphone jack or line output, Airstream does a "shade tree" solution, probably adding a few resistors to cut the high level of the speakers down to something a line input can tolerate.
Unfortunately, your unit did it correctly, thus robbing you of the headphone jack. All is not lost though, there is no reason you can't "Y" the headphone jack and use it in both places. You increase the chance of a ground loop (hummm) but it's doable. Is anything plugged into the headphone jack? Is the headphone jack controlled in the menu? (Usually your choice is line output or volume control.)

[stevejones]

Originally Posted by Mollysdad

Speakers should never be used to drive a line level input. So, in many units where there is no headphone jack or line output, Airstream does a "shade tree" solution, probably adding a few resistors to cut the high level of the speakers down to something a line input can tolerate.
Unfortunately, your unit did it correctly, thus robbing you of the headphone jack. All is not lost though, there is no reason you can't "Y" the headphone jack and use it in both places. You increase the chance of a ground loop (hummm) but it's doable. Is anything plugged into the headphone jack? Is the headphone jack controlled in the menu? (Usually your choice is line output or volume control.)

I think Y connectors are the only possible route unless I want to take the back off the TV which I don't

Nothing plugged into the headphone jack. No separate control for it.

[stevejones]

Originally Posted by link2dks

A couple of comments. First of all I'm no A/V expert. I haven't noticed the latency you mentioned b/c I have never used the TV speakers and the cabin speakers from the Polk at the same time. To me that was the point of doing the conversion with the DAC. Am I missing something?

The OP wanted to be able to control the TV speakers separate from the Polk Audio Speakers (including turning the TV all the way down). That's why he did the conversion with the DAC.

In my case I wanted some of the sound coming from the TV to achieve something more like surround sound (think center channel), not just sound above my head. I also wanted to reduce what I felt was a lot of distortion from over driving the Polk Audio unit with a signal from the TV speaker/headphone jack (wherever it is wired to). Using the Prozor DAC does reduce a lot of this distortion. However the signal I'm getting from it is so low in amplitude that I have to turn the Polk unit up really high, so there is some distortion from that.

Anyway last night we tried watching a show using the Prozor DAC to drive the Polk Audio unit with the TV sound turned off. I guess that was OK. Need to work on adjusting the subwoofer since the signal driving it now is so much lower in amplitude.

Steve