Llewelyn

Hi guys

My Japanese 91 S4 doesn’t have the factory amp fitted by the side of the passenger seat. What it does have though is a big loom of cables (two heavy gauge red and a bunch of what look like speaker output wires) all neatly tied together and connected in a continuous loop using factory bullet connectors. I’m convinced it’s the factory loom and that no amp has ever been installed.

Has anyone else got this? Is it possible to retro fit a BQB 80 (or whatever the correct 91 amp is) and is it worth it?

My speakers sound pretty good but my head unit flickers when I turn the volume up. It’s a Becker Traffic Pro and has been installed very nicely.

I suspect this is due to the low impedance of the 10 speaker stereo system so I’m thinking of adding a factory amp if it’s worth it...

Any advice appreciated

Rob Edwards

It sounds like somebody ran speaker wires from the Becker to the passenger seat and spliced them to the factory wiring out to the speaker. Got pics of the passenger seat area? It sounds like you have the power wires for the factory 6-channel amp but not the connector (?)

I have a '93 'open' right now and can shoot pics if that would be helpful.

Speedtoys

A refurbed OE amp is a great unit actually...928intl will have them, and they can be re-capped just up the road.

The in dash unit is about 1/2 the wattage output of the offboard amp.

THis is what I use, even with the updated ApplePlay porsche head unit

rbrtmchl

This may be unrelated to the problem you are seeing, but for a different radio, a CDR-220, Jim Corenman posted about a problem with the power wires in the 928:

Quoting Jim Corenman: "The CDR-220 connects to both the continuous (bus-30) 12-volt connection and the switched (bus-15) connection, as usual. The first keeps the memory alive, the second switches the radio on and off. However, this unit is relatively unique in that it draws its primary power from the continuous 12-volts, and uses the switched 12-volts as a power on/off signal.

So with the key off, you can press the "on" button on the radio and it comes on, for up to an hour. This is terrific for hanging out in ferry lines for example. And when you turn the key on, then the radio comes on, if it was on when the key was last turned off. Pretty slick!

The only problem with that scheme is that the continuous 12-volts (bus-30) wiring for the factory radio is a skinny 1-mm wire that comes from the filter located with the amp, next to the passenger seat. When the head-unit keys the amplifier on, the voltage drop through that skinny wire plus the drop to the amp was enough to turn the radio off again-- resulting in just a "thump, thump" whenever the radio was turned on. The fix was to run a separate 14-ga wire from the amp connection on the CE panel (E-24 for an '88) direct to the continuous +12v radio connection."

Here is the link:

https://rennlist.com/forums/928-foru...ml#post7234537

Hilton

From memory, Japan market got some unusual packages, including an "Exclusive" model which had a Nakamichi stereo setup with an amplifier mounted on the front of the CE panel wood cover.

Your description of the wiring by the passenger seat sounds like the standard factory harness to connect the ends of the speaker and radio harnesses together under the cover by the passenger seat. I'll go take pics of my 87 - slightly different stereo harness config, but mine also didn't have the regular additional amplifier, and also has the same standard factory din male and female connectors down there.

What you need isn't a BQB-80 (which was used thru '88), its the later 6 channel amp from blaupunkt, which is rarer

However - its worth investigating the wiring to see if you can find where the amp used to be?

Hilton

Here you go - pics of where the factory amp would have been if my '87 had the standard stereo option package. This is the factory "no hifi stereo" harness connector setup - retains the DIN plugs etc.

(It only has 4 speakers from factory - same layout as the early cars with the perforated door panels and perforations behind each seat on the quarters).

Hilton

And here's pics of the Nakamichi setup from a Japanese S4: https://rennlist.com/forums/928-foru...michi-amp.html

Llewelyn

Awesome advice guys, thanks for the info

I reckon I’m going to source a 6 channel amp here in the UK and reinstate it. I don’t have any pics of my loom yet but I’ll take a couple tomorrow and upload them ... I’ve been reading up and it looks like the 6 channel amp has a separate pair of LF outputs that can cope with a 2 ohm load which makes perfect sense. I just need to find one locally!

@hilton I’ll check out that Nak set up, it sounds interesting 👍🏻👍🏻

Popoboy944

I just repaired my bqa80 amp (mine did not have a bqb80) and happened to take a picture of the harness installed if it helps. Mine is an early 87 with the hifi option. I was really impressed when I heard it working for the first time. One black radio feed, red 12v power, brown ground, and 4 speaker outputs. Each one has 2 pins. I think I have seen other harness setups than this as well, but I'm no expert.

Llewelyn

Thanks for posting! Mine definitely has the later 6 channel amplifier though... I’ve managed to source one now so hopefully I can get it installed later next week.

here’s a pic of my wiring, I had a prod around today and it seems like the din cable (black round plug from the pre-outs) has been removed or tucked away somewhere as I can’t see it behind the stereo or at the amp location. And as suggested above the speaker cables have been extended up to the behind the stereo.

It should be easy to retrofit the amp though. I will just need a new din cable (I actually have a spare Bang & Olufsen one which should work) and a din to RCA adapter for the head unit.

I believe because the rears and the rear bass cables are both joined and being fed by the rear speaker output, the Becker head unit is struggling to cope with the 2 ohm load hence the flickering... To be continued

Rob Edwards

So clean!

You are going to need some two-pin DIN speaker connector pigtails to splice back onto the ends of the factory wires so you can connect them to the 6-channel amp. You want the compact connectors, as the sockets on the 6-channel amp are closely packed together and the larger aftermarket DIN connectors won't fit.

Like this:

https://www.cricklewoodelectronics.c...Terminals.html


Not this:


Fortunately the good ones seem to be more regularly available in the UK.

Llewelyn

Thanks Rob!! Connectors now on order from Cricklewood so when they arrive I'll make a video of the installation and post it here for anyone interested

I got the used amp this week and can't wait to get it installed!

Kiwi928S4

Hi Llewelyn,
I am looking at putting an original 6 channel amp back into my car - 1991 S4 ex Japan RHD so would be very keen to see your video and photos of the install please. I am in New Zealand
Kind Regards
Ken

Speedtoys

I have a recapped and serviced clean performing OE 4-channel factory unit I would sell for $100+shipping.

This was serviced by https://creativecaraudioshop.com/

Mark Anderson

that’s a great deal Jeff, if anyone needs a late 6 channel we have 1