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It should be possible, with a bit of jiggery-pokery, to wire the front output to the rear output, stick a cheap potentiometer in somewhere (say under the dash or in the glove box) and create a rear speaker setup. Once a decent balance has been achieved between front and rear, the pot shouldn't need to be touched again, so can be hidden away. The caution would be that if the speakers are wired in parallel, then there is a halving of impedance to both sets. With 8 ohm speakers, this would give a total load impedance of 4 ohms for each speaker . This should be OK for most modern amps, but I would recommend checking the impedance of the existing speakers and the rating of the existing amp. If the original speakers are already 4 ohm, then dropping to 2 ohm might be more than the amp is happy with. Having said that, if the speakers are wired in series, then this should be safe - two 4 ohm speakers in series, for example, makes a total load impedance of 8 ohms (or two 2 ohm speakers = total load of 4 ohms) which most amps should be OK with. Bear in mind that changing the overall impedance will increase or decrease the power output of the amp.Parallel wiring = increased output power and Series winding = decreased output power. So a Series setup might result in insufficient amp grunt (although probably of no concern in a car setup for most
Zed, I can’t find any specific DSP adjustments that help my no sound issue from my rear speakers. As mentioned earlier, my PCM is fried so reinstalling and verifying the fader position is not an option. I can’t imagine that the fader was to the front when I uninstalled it as there were no complaints from the kids and my wife let the kids control music from her phone. Thankfully no Swifties, but Noah Kahan does get overplayed.
I also read the thread about the Most bypass. I want to verify that I conceptually understand everything since some of your thread recs are over my head.
Since Andy verified that there are no rear speaker RCA’s from the Chstek, I would T-Connect the RCA R&L cables with 2 long cables.
Splice in a potentiometer like the one pictured.
Find the R&L rear speaker wires going into the Bose amp, remove them and connect the speaker wires from the potentiometer. Use the potentiometer to control signal to the rear speakers. Use fader and potentiometer to set final front/rear balance.
Queations: I believe this set up would just half my output signal. Do I need to add a 2 Channel amp for this set up to sound legit?
Maybe not worth the hassle, just trying to decide if it’s worth taking on another project
So I believe if you don't have Bose, you're relying on the amp in the head unit, and therefore 4 channel audio should work just fine (i.e. rear output and fader would work fine).
With Bose, you are converting a 2 channel (stereo, analog or digital) signal into a MOST signal to the Bose amp, so fader is lost. There is an analog rear channel out that is not typically wired from the factory, but can easily be added. If you use an external 4 channel amp, you could utilize this to get a separate rear signal and have fader control (see below). Alternatively, if someone made a 4 channel to MOST adapter, that might allow Bose to have fader support, but I have never seen such an adapter, nor do I know if this is even how Bose manages the fader (it's possible they send a 2 channel audio signal with a separate signal that indicates fading, surround, etc.).
So I believe if you don't have Bose, you're relying on the amp in the head unit, and therefore 4 channel audio should work just fine (i.e. rear output and fader would work fine).
With Bose, you are converting a 2 channel (stereo, analog or digital) signal into a MOST signal to the Bose amp, so fader is lost. There is an analog rear channel out that is not typically wired from the factory, but can easily be added. If you use an external 4 channel amp, you could utilize this to get a separate rear signal and have fader control (see below). Alternatively, if someone made a 4 channel to MOST adapter, that might allow Bose to have fader support, but I have never seen such an adapter, nor do I know if this is even how Bose manages the fader (it's possible they send a 2 channel audio signal with a separate signal that indicates fading, surround, etc.).
*all of this could vary depending on the exact unit you have.
So, I curious about this. I think the factory quadlock for both Bose and Non-Bose also have the same F/R speakers output (or they actually don't?) How does the Android unit know not to output to the quadlock? There's no settings that says use A or B.
So, I curious about this. I think the factory quadlock for both Bose and Non-Bose also have the same F/R speakers output (or they actually don't?) How does the Android unit know not to output to the quadlock? There's no settings that says use A or B.
It outputs both. The quadlock contains amplified speaker level outputs that go directly to the speakers. The analog RCA (and optical digital) output is designed to go to an amp. Only one will be used since only one is effectively hooked up based on the equipment in the car (e.g. a Bose car won't have anything connected to the speaker level outputs in the quadlock).
It outputs both. The quadlock contains amplified speaker level outputs that go directly to the speakers. The analog RCA (and optical digital) output is designed to go to an amp. Only one will be used since only one is effectively hooked up based on the equipment in the car (e.g. a Bose car won't have anything connected to the speaker level outputs in the quadlock).
I see...so for Bose equiped, the speakers output are null in the quadlock? Do you know if the pins are wired or empty? Or it's wired but just not connected to anywhere? Wish I've taken pics of the quadlock wires.
I see...so for Bose equiped, the speakers output are null in the quadlock? Do you know if the pins are wired or empty? Or it's wired but just not connected to anywhere? Wish I've taken pics of the quadlock wires.
I think the wires are present in the quadlock, but not wired elsewhere in the car. Not sure where those wires end. Didn't look that carefully to be honest. It's the same setup with the PCM, except the MOST connection is in the quadlock.
I think the wires are present in the quadlock, but not wired elsewhere in the car. Not sure where those wires end. Didn't look that carefully to be honest. It's the same setup with the PCM, except the MOST connection is in the quadlock.
Got it. I think the wires are not connected to anything then. So the Android unit still outputs through the quadlock wires. I guess the easiest is to tap the Rear pins and connect it directly to the rear speakers.
I would just reach out to the seller. If you plug your PCM back in, do you get power? If so, something must be wrong with the unit, or some of the wiring in the android harness is wrong (doesn't match your pin out)
I agree, you need to put the PCM back in to test that there is nothing wrong with the car side of the loom/wires
If this works and the Chstek does not when you refit it then my guess would be its a defective unit. You are installing a different unit to the rest of us as it's going into an older vehicle so we don't have any specific experience of it, but we have not had a report of a 7862 unit being dead on arrival, so hopefully this is just a connection issue that can be resolved
@andy2111 can you confirm that the fader works as expected in non-Bose cars? If so, I believe there must be Front LR and Rear LR outputs via the quadlock. According to the guide, you don't use the Front LR RCAs for non-Bose. Please confirm that the fader issue is just for Bose/MOST cars.
Yes the fader works on non-Bose cars (Chstek same as Erisin in this regard)
So if the quadlock audio output pins are live, even on a Bose car, then perhaps you can pop out the current connector that goes to the ASK amp (in non Bose) and replace it with the one above to "extract" the audio feed
This assumes the car-side of the quadlock on a Bose car has the same quadlock e.g. on a non-Bose car you can pop out the amp connector.
If the connector block is different then the solution is to buy a quadlock extender and then cut the speaker wires and attach to RCAs
I did something similar on my Erisin unit where I wanted to take the 4x line outs and feed them direct to the ASK amp to avoid sending an amplified signal to the amp. So something similar would be possible if the connector block and adapter solution does not work
the CHSTEK HU produces a 4ch (Front LR + Rear LR) audio output. This is hardwired into the quadlock for non-Bose cars and the fader works as expected on the HU
For Bose cars:
Front LR RCAs are provided
Rear LR RCAs are not provided on the harness but could be added, per instructions here (thanks @drawz )
using the Front LR RCA > MOST adapter, all speakers are powered by the Bose amp (e.g. 991.1 5.1 array). You cannot alter Front/Rear fade from the HU - attempting to do so just changes volume
for the HU fader to work, Front LR and Rear LR must be separated. Merging the 4ch HU RCA outputs into the MOST adapter, for example, won't work - as the MOST output is still "flat"
Options for HU fader control are therefore (after adding the Rear LR RCAs):
4ch MOST adapter - per Russian links (see instructions for this unit here). This is untested and (from what I've read) may not be a reliable solution, quite aside from the difficulties of obtaining one
2ch MOST adapter (i.e. as current), with separate amp to service the Rear LR RCAs, outputting to the re-routed rear speakers. The Bose amp then only controls the front speaker array
We're not in new territory here... many others have gone through the same journey and Rennlist and other forums have lots of installation stories.
For fader control outside of the HU, it's possible that relative speaker volume could be tweaked by adding resistance and/or putting Front+Rear L and Front+Rear R speakers in parallel.
Finally, there is some evidence that fader preference is "remembered" by the Bose amp, similar to volume (see this post). It would be great if a Bose-owning volunteer could test this. If correct, it would provide a means to statically set the fader preference, which may be sufficient for some.
All of this is super helpful. To be clear, for a Bose vehicle, tap these wires and connect them directly to the rear speakers and I should have sound in the rear. Add an attenuator to gain control of how much sound.
All of this is super helpful. To be clear, for a Bose vehicle, tap these wires and connect them directly to the rear speakers and I should have sound in the rear. Add an attenuator to gain control of how much sound.
Remember that the output from the quadlock is already amplified, so you will need attenuation somewhere in the signal path. Most attenuators are directional so look for the arrow printed on them which signifies the direction the signal 'flows'. The strength of the attenuation will determine how loud your rear speakers will sound, so you may need to experiment.
Not sure about the comment "attach them directly to the rear speakers"
Either a line level signal for the rear needs to be fed into the Bose amp (so attenuators are needed), or an amplified signal needs to go direct to the rear speakers (bypassing the amp) in which case attenuators are not needed
Not sure how volume control will work in this scenario and it might be a bit unbalanced without fader control
Alternatively, take the quadlock amplified signal for all 4 speakers and apply attenuators to all channels and then you have 4x line level RCAs with full fader and volume support
08-11-2024, 10:31 PM
