When I bought the 940 in 2003 it had a low-buck aftermarket CD-receiver and the Volvo amp was gone. The OE Volvo speaker wires were spliced to the head unit. Original Volvo speakers all around (2-dash tweeters, 2-front door spkrs, 2-6x9’s in the rear shelf). Sound was OK, if a bit dim. I replaced the head unit with a Blaupunkt “San Jose” CD/MP3 player with an advertised 50W/ch. (Prob. 20W or so, continuous RMS). The rear speakers were changed out for a pair of Infinity Reference 6935i’s.

This has been the setup until today. Not bad sound, but lacking depth, and the kind of bass that the 6x9’s should give. Higher levels just had the feeling that the head unit was straining. The power to the rear was going through a lot of small wire and connections.

Solution: The HA-3141 “Volvo” amplifier. These were the rear speaker amps on some mid-to-late 80’s 760 cars and maybe others. The amp’s front panel says 40W/ch. This may be RMS or ‘peak’, I don’t know...it has hellacious big heat sinks. The amps were mounted either up front under the dash on the driver’s side or screwed to the underside of the parcel shelf in the trunk. I snared a couple of them at the last half-price weekend at the PnP: $5 each!

The Volvo amps use a 6-pin DIN cable and connector which is hard wired into the amp. This plugs into a socket in the back panel of the Volvo radio/cassette to transmit the low-level audio signals. This creates a challenge when trying to mate these amps to an aftermarket (RCA plug) head unit. I cut the DIN connector off the amp cable and disassembled the amp enough to be able to trace the wire colours and determine what went where. Then I soldered a pair of salvaged female RCA jacks to the amp input wires, along with a length of plain wire to the amp’s remote turn-on lead. I had pre-wired the 940 with RCA cable from the line outs of the Blau into the trunk, along with a 10-ga power wire from the battery. The RCA cables incorporated a siamesed turn-on wire. I tied off and insulated all this at the trunk end, and that’s the way she went for 4 years.

Finally, over the past week or two, I converted the amp to the RCA jacks, mounted it to the underside of the parcel shelf, disconnected the speakers from the wires from the head unit internal amp, and hooked everything up. The sound is MUCH better! The volume comes up linearly with the rotation of the control, no straining, and there’s improved depth and, well, sharpness. The bass is good enough that I’ve shelved my plans for a subwoofer.

I think I paid about $20 for the 16-ft RCA cable, so along with some solder and bits of wire and connectors from my junk drawer, I’ve got less than $30 in the project.

--
Bob (son's 81-244GL B21F/M46, dtr's 83-244DL B23F/M46, my 94-944 B230FD and 89 745 (LT-1 V8); hobbycar 77 MGB, and a few old motorcycles)