Strange pulsing whine in speakers caused by bluetooth

[blert]

Been working with Crutchfield (tried all their suggustions so far to no avail) and have also posted on r/CarAV (no help yet though). Searches lead only to bluetooth issues while playing (static, popping, etc.). Maybe someone here has dealt with this before...

Having a freaky little problem... When the head unit is searching for a Bluetooth connection I get a whine from the speakers. It is not constant, eight seconds on, ten seconds off, repeat. If I connect my phone the pulsing goes away, disconnect my phone and it comes back. Also, if I leave my phone disconnected and go into the head unit settings and re-initialize the Bluetooth it goes away until I reconnect and then disconnect my phone, at which time the pulsing whine comes back. It can really only be heard (by me anyway) while the system is muted or set to a source with no input. Volume of the whine does change depending on the system volume when muted. It's not the alternator, the truck is not running. No other accessories are on.

Things I have tried... Disconnect antenna, no joy. Re-did the ground wiring in the harness, no joy. Added a 12ga ground wire from harness to chassis, no joy. Disconnected microphone, no joy. Checked for head unit firmware update, no joy.

- JVC KD-X380BTS
- front: JBL Club 8622F
- rear: Infinity REF-8632CFX
- no other hardware

Any ideas?

 

[blert]

Today's experiments...

Factory reset, no joy.
Removed the 8pin harness adaptor (amp control) to reduce the amount of wires, no joy.

Got back with Crutchfield and arranged a return. It has to be either a bad unit or an issue with JVC's design. Going to try the same model again and hope it's just a bad apple. New unit has already shipped. If this one does the same thing then it is a JVC issue and have already confirmed that I can then return that one for something from a different manuf.

Crutchfield customer service is the best.

 

[Todd Z]

Hard reset phone....

 

[blert]

Nope, not it. Phone is easily taken out of the equation. I left it out of range, turned off bluetooth, even just turn it off completely.

 

[blert]

Freakin' frak! Replacement unit does the same thing. I cannot fathom what is going on here. Is there anything in the truck that cycles power 10 seconds off, 8 seconds on repeatedly? Everything in the truck is off and/or unplugged, key on but truck not running. I really want to love this head unit, it is quite nice for being lower end.

 

[Wade J]

I would assume this noise only became a problem after the new radio install correct?

How clean are your battery terminals? I have seen noise introduced into a car audio system from bad grounds not just the radio ground. If you live in the rust belt this can be an issue as well.

How old is the battery?

Do you have another 12v battery laying around that you can use for a test. just hook up the JVC radio 12v constant and 12v switched (red and yellow) together to this external battery + ( I would put a fuse in line just in case) and JVC radio ground (black) wire to the external battery - and see if the noise continues.
The only thing connected to this external battery will be the JVC radio.

If the noise is NOT present with an external battery not connected to the vehicle this would say it’s something on the truck side causing the issue.

If the noise IS present with an external battery not connected to the vehicle then it’s the head unit itself.

This will at least tell you if the JVC or the truck is the issue.

Good luck sir

 

[blert]

Battery is less than a year old. Terminals are clean but I will clean a re-seat them anyway. The three major grounds are clean but I will clean and re-seat them too.

I don't have a spare battery but I think I may still have an old PC power supply I can use to grab 12 volts. Will have to search for it.

Going to pull the harness apart one wire at a time and see if I can isolate it to a specific wire.

 

[blert]

Pulled the dash bezel out and disconnected everything attached to it, no change. Cleaned and tightened battery terminals, nope. Disassembled and cleaned the four grounds (that i could find) in the engine compartment, nope. Disconnected orange illumination wire, nope. Disconnected one speaker at a time, nope. Tried each speaker by itself, nope. Again ran a new ground from headunit to chassis, nope. Removed battery from truck and brought it into the cab, hooked up headunit directly to battery, nope.

These new JVCs are pretty much Kenwood eXcelons as far as features and settings go. I am guessing they had to cut costs somewhere to be able to offer what they do at a price well below an eXcelon. The Bluetooth module must have been one of those things that got cheaped out on.

Going to call Crutchfield and exchange it for a Pioneer (I think) unless someone has any ideas.

 

[Wade J]

Yeah it must be the JVC then. I have never had any issues with Pioneer but the last time a bought one was 5-6 years ago.

At least Crutchfield is taking care of you.

 

[tech77usa]

You may be asking too much wanting full quiet on selected unused inputs. It's sounding like the blue tooth module is polling for devices and it's shielding is leaky and so the rf signal may show up on unloaded inputs. Try adding pi rf filters to inputs and power.

 

[blert]

You may be asking too much wanting full quiet on selected unused inputs. It's sounding like the blue tooth module is polling for devices and it's shielding is leaky and so the rf signal may show up on unloaded inputs. Try adding pi rf filters to inputs and power.

Yeah, I understand JCV is kind of a "budget" option but it's not just on unused input, it on all inputs all the time, including FM. I talked to JVC, Crutchfield, an in-town car audio pro, r/CarAV: it is so far unheard-of. Last night I did find some info in the DIYaudio community. Some of these guys make their own bluetooth speakers and a few of them have had the exact same issue. From the replies they got it seems to point to a cheap bluetooth module and the way the module shares a power input with the internal amp. It looks like JVC forgot to use a proper DC-DC isolator when they stepped down the power to the Bluetooth module to 5volts and/or a proper EMI filter before the internal amp. No ammount of anything i can attach to it will solve the problem, it is internal to the unit and a design problem. This is what you get when you have to cut costs to keep the price down. Anyway, Crutchfield has a new Pioneer heading my way.

 

[blert]

Just installed a replacement Pioneer DEH-S6220BS and so far so good. A quick test showed absolutely no whine from the Bluetooth module.

Avoid the JVC KD-X380BTS! (and probably all its variants: 280, 480, etc) At least for about a year or so. It is a remarkable little unit with all the features of the higher tier Kenwood eXcelons at the price of a JVC but they need to do a hardware revision on it, a firmware update will not fix its issue.