P38A Hifi peeps update!!

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Mark Piercy

Mark Piercy

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Ok then, my existing stereo is a Kenwood, usb, CD and radio.
It works very well at low volume with the amps in the doors and the sub.
I want it fit a more modern JVC with Bluetooth and all that jazz.
The problem is the new JVC doesn't produce any sound at all even from the sub.
All the connections are iso and sound. The JVC will work in my wife's car without any adjustments.
So the question is why doesn't the new JVC not work and the Kenwood does?
I really don't want to go rewiring all the doors and to be honest I like the speakers the way they are.
Any suggestions please.:D
 
biketeacherdave said:
Is the blue wire from your new head init connected ?
Click to expand...
It is and is connected to turn on the sub amp. I've fitted a RCA connection to the cars sub wire and it works with the old Kenwood head unit.
The model I'm trying to get working is a JVC kd-x351bt.
Thanks b t Dave.:D
 
Last edited:
The cd changer is original but isn't used anymore swiss, the current radio head unit is a Kenwood and the replacement is a JVC. The cd changer hasn't been used for nearly two years.
 
It's the usual problem, where using speaker outputs from head unit to drive the HK Door amps is less than ideal. This is because the HK amps are balanced line-level inputs and the head unit speaker outputs are not. Some head units will work, but others wont. That unit also has some speaker out settings that change depending on 2 or 3 way crossover speakers, plus with & without amplifiers. None of the modes produce the 5 channel output you need for the P38 system !!

There are several options:
1) use one of the resistor network bodges mentioned on here. Might work but any earth problems will cause buzz or noise.
2) buy one of the "InCarTec" adapters ( probably just a boxed version of the Landyzone resistor circuit)
3) Use balancing transformers to convert the Head Unit Phone outputs to balanced signals for the HK Amps.

My android system used method 3, and I get totally clean buzz & hum free audio in all 4 doors & Sub. My head unit has speakers outputs disabled, and uses the 5 line outputs (FL,FR,RL,RR & Sub) to feed 5 audio transformers. The balanced secondary output then connects through the P38 10-way connector to the door amps. I specifically looked for a stereo with 5 Line outputs so I could do this !!
 
pwood999 said:
It's the usual problem, where using speaker outputs from head unit to drive the HK Door amps is less than ideal. This is because the HK amps are balanced line-level inputs and the head unit speaker outputs are not. Some head units will work, but others wont. That unit also has some speaker out settings that change depending on 2 or 3 way crossover speakers, plus with & without amplifiers. None of the modes produce the 5 channel output you need for the P38 system !!

There are several options:
1) use one of the resistor network bodges mentioned on here. Might work but any earth problems will cause buzz or noise.
2) buy one of the "InCarTec" adapters ( probably just a boxed version of the Landyzone resistor circuit)
3) Use balancing transformers to convert the Head Unit Phone outputs to balanced signals for the HK Amps.

My android system used method 3, and I get totally clean buzz & hum free audio in all 4 doors & Sub. My head unit has speakers outputs disabled, and uses the 5 line outputs (FL,FR,RL,RR & Sub) to feed 5 audio transformers. The balanced secondary output then connects through the P38 10-way connector to the door amps. I specifically looked for a stereo with 5 Line outputs so I could do this !!
Click to expand...
Excellent, thank you very much for pointing that out and taking the time to look into it for me. Now I understand, so I'll look for the resistor trick and see if that works. Thanks again.:cool:
 
Hmm, I took a look at the incartec site, I might just stick to the Kenwood unit.... To many variables and "should be used with this other unit".... And that starts to add up to the price of the JVC unit... Electronics isn't my thing..... I'll search for the resistor mod.. ;)
 
Hmm, that just brought up our conversation on the search.
Sorry Mr P', you don't know the name of the link do you?
I did try "resistor network" but I've no idea what it would be called?? Please.;)
 
Last edited:
Weird, I found a link in the adverts below..... emoticon-stock-illustration-4367198.jpg
 
For the price of a rebuilt gearbox? Ooh and a rebuilt transfer box.mmmmm niiice.
I've never used the bloody thing.
I've sent an email to Incartec asking about their adapter for the bus.
 
Mark Piercy said:
Hmm, that just brought up our conversation on the search.
Sorry Mr P', you don't know the name of the link do you?
I did try "resistor network" but I've no idea what it would be called?? Please.;)
Click to expand...
Here's the link to the "Ray Ambler Attenuator" https://www.rangerovers.net/threads/head-unit-upgrade-again.35296/post-420833

Depending on the aftermarket stereo speaker output, it IS important to get the wires to door amps the right way round. Some head units have floating or bridged speaker outputs, whereas others have one side earthed. In the 10-pin connector five of the wires have Black stripe. These should be on the lower side of the attenuator.

. . . . . . . as I said good luck if you avoid buzz or hum !! Why go to all the trouble of making 5 resistor ladders, when 5 transformers does the trick properly !!
 
pwood999 said:
Here's the link to the "Ray Ambler Attenuator" https://www.rangerovers.net/threads/head-unit-upgrade-again.35296/post-420833

Depending on the aftermarket stereo speaker output, it IS important to get the wires to door amps the right way round. Some head units have floating or bridged speaker outputs, whereas others have one side earthed. In the 10-pin connector five of the wires have Black stripe. These should be on the lower side of the attenuator.

. . . . . . . as I said good luck if you avoid buzz or hum !! Why go to all the trouble of making 5 resistor ladders, when 5 transformers does the trick properly !!
Click to expand...
Thank you mr P, that all went right over my head.....:oops:
ill wait for a response from incartec and decide what ill do from there with all the info you've given. thanks again for your efforts mr P.;):D
 
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