4580 JRC Add Line Out

[xtreamdev]

I have a DVD Nav Headunit in my Lancer and i want to add aftermarket amps to the radio.. But as you know most factory radios dont have rca out.. line-level out.. So I opened up the unit found the AMP IC and followed the imput to some "4580" jrc chips two of them.. can i solder my rca wires to the output.. do i need diodes capacitors etc this is a car radio..

Thanks for the help..

[Redshift187]

That's a NJM4580 dual op-amp. It's probably line level out (ie RCA in this case). Whether or not you need capacitors or other parts depends on the circuit surrounding the op-amp.

Given that it's used in a car environment, you should put a capacitor (try 22uF 50V electrolytic) in series with the output followed by a resistor (try ~22k ohm) to ground.

[xtreamdev]

Originally Posted by Redshift187

That's a NJM4580 dual op-amp. It's probably line level out (ie RCA in this case). Whether or not you need capacitors or other parts depends on the circuit surrounding the op-amp.

Given that it's used in a car environment, you should put a capacitor (try 22uF 50V electrolytic) in series with the output followed by a resistor (try ~22k ohm) to ground.

It looks like it uses the NJM4580 as a line driver for the TDA7386 AMP.. I dont plan on using the built in power at all so the amp will not have speakers pluged in.. But i do want to use the NJM4580 to output to RCA.. I found pins 11, 12, 14, and 15 to be the Line-IN at that amp ic and pin13 sig ground.. I was just thinking of putting 4 rca cables on pin 11,12,14,15 and ground all of them to pin 13..

Here are some pics i took so you can see what im looking at.. I know the cap the brown ones near the amp run in serial with the am imput one for each they say 224

IMG_0406.jpg

IMG_0411.jpg

Thanks for the info..

[Redshift187]

It looks to me like C107, C127, C147, C167 are all electrolytics in series with the output of the op-amps to block DC.

10uF series -> resistor to ground -> resistor series -> muting transistor -> resistor series -> capacitor to ground -> brown capacitors? (0.22uF)

It's a very typical line out circuit. You can certainly tie some RCA outputs to the TDA7386 input pins. You may be able to find a better (easy to solder) ground point than pin 13. Just probe around likely spots and check for continuity to pin 13.

[Artie]

Actually, those caps are probably on the input pins, as shown here:

The outputs are bridged.

[xtreamdev]

Originally Posted by Artie

Actually, those caps are probably on the input pins, as shown here:

The outputs are bridged.

Yes the brown capacitors @ c169, c129, c109 and c149 are on the inputs to the TDA7386 so get the signal after the caps or before?

if the -> in brown caps -> tda7386

[Redshift187]

Everything I said was after the op-amps, before the TDA. So yes, get your signal on the input pins of the TDA.

[Artie]

Here's a thought too: If it was me, I'd prefer not to go into the internals of the head unit. Why not build a simple spkr-to-line-level convertor? With the right selection of resistors, you can keep the TDA7386 down in the 1-watt range, which keeps the THD below .05%. That would be fine in a car environment, and you can adjust the resistor values to get whatever output voltage level you prefer.

Here's one way: (Btw, you want to balance the two speaker-wire output loads since this device is "bridged".)

The two inputs are LF+/LF- speaker outputs. Obviously, you'ld need four of these circuits.

[Redshift187]

I like that idea Artie.

[xtreamdev]

Originally Posted by Artie

Here's a thought too: If it was me, I'd prefer not to go into the internals of the head unit. Why not build a simple spkr-to-line-level convertor? With the right selection of resistors, you can keep the TDA7386 down in the 1-watt range, which keeps the THD below .05%. That would be fine in a car environment, and you can adjust the resistor values to get whatever output voltage level you prefer.

Here's one way: (Btw, you want to balance the two speaker-wire output loads since this device is "bridged".)

The two inputs are LF+/LF- speaker outputs. Obviously, you'ld need four of these circuits.

That is what I had before a "low level converter" but past 1/2 volume we saw distortion on a scope.. plus to me it did not sound good.. i had pop and noise.


IMG_0419.JPG

IMG_0418.jpg

well its done now.. I just need to put it back in the car and see what it sounds like I wished I still had access to the scope to see what it does now.. I belive those opamp should be doing around 4volts.. so that should be perfect for my amps..