Removing an external amp help needed

[A993LAD]

Hi folks hoping for some help here. I'm quite used to playing around with car electrics but don't know much about in car entertainment systems and how they work.

I have a Porsche 993 which I've owned for quite a few years and with it I inherited an nice period Becker Indianapolis pro head unit that suits the car and I'm keen to retain if possible.

But the previous owner wanted to improve the sound quality and installed an Alpine 360 external amplifier in the the front luggage area under the bonnet. Not only does this take up half the storage space in the luggage area but it also seems to have a massive bird's nest of huge cables that run from the front of the car up under the dashboard and behind the head unit.

Ideally I would like to remove this amplifier and all the cables that are associated with it.

I'm not sure if the amp is a good piece of kit as frankly the sound quality in the car is pretty poor because the speakers are rubbish, the car squeaks, rattles and groans and mostly I drive it with the roof down at high speed with loads of wind noise.

Does anybody know if this head unit has to have an external amplifier or can I just connect it straight to the speakers and get rid of the amplifier plus all its associated massive collection of cables?

Any helpful tips gratefully received and I have attached a few photos in case they are helpful

[996Type]

Hi,

There should be a line out at the back of the existing head unit, probably phono, and then powered return cables from the amp back into the cabin to the various speakers which I think are just visible in your pic. If the head is capable, there will also be powered outputs on the back ready to go directly to the speakers, either unused or maybe powering the rears directly.

If the sound isn’t that good now, it may deteriorate further once the amp is removed and you wire direct from the head unit though.

One option is to update the speakers when you strip the amp out. You’ll need to get to them anyway to reintroduce in cabin wiring potentially when you remove the amp.

Just reuse the cable you have if it’s good enough with shorter runs back to the head.

The other would be to put a slimline amp under the passenger seat (or maintain the cabling and use the void in the spare wheel well to house the current amp if it didn’t fit under the seat).

I had a similar set up to you but with a six disc changer in the boot in the same position, I took this out as I just use my phone for music but didn’t bother to remove the relatively thin cabling that went with it yet.

When I do mine I think I’ll introduce an under seat amp but my speakers need replacing as well as they are bulky and ugly and technology has moved on since mine was butchered around to fit them.

There’s a good sound guy in Wembley you might be aware of depending on how far you want to go who works on 993’s.

For example he might also suggest sound matting to minimise the cabin noise to make a better show of the kit you already have or intend to fit, taking the old heavy door insulation out in the process. It can all be done DIY as well.

Depends how far you want to go, I expect it’s diminishing returns based on the age / NVH within a 993, but it’s still good to have decent music capability for when you have longer journeys to make.

Edited by 996Type on Monday 17th October 21:29

Edited by 996Type on Monday 17th October 21:30

Edited by 996Type on Monday 17th October 21:31

[A993LAD]

Hi thanks for the quick answer

I probably wasn't very clear about my requirements here and I'm really not too worried about the quality of the sound system. My point about the noise in the cabin was really to illustrate that it's the sort of car where it probably doesn't matter if it's a good sound system or a bad one you'll never be able to hear it anyway if you are using the car as intended

My primary motivation is to get rid of the amp under the bonnet and all of the associated wiring which seems far too much thick cable for such a small car.

But ideally I would still like to play some music on occasions even if the quality is appalling. I just didn't know if the head unit could power the speakers without an amp. if it can I will strip the amp out and then see how it works.

Cheers

[996Type]

That’s great, whip the head unit out and check the outputs on the back.

If you have any powered outputs, trim down the cables and strip out the cables to the front

It could be just a head unit with no in built amp but that would be rare I would have thought.

Be interesting to see how you get on!

[996Type]

This is a similar Becker configuration, option for both amp and power straight out.

You’ll need to block connect your speakers back in but a local car hi fi place should be able to make up the connections for a few quid if you go down this route.

[A993LAD]

Excellent many thanks

[The Wookie]

Not sure about the 993 but I know 928s have speakers with a different resistance to the common 4 ohm that your aftermarket amp will probably be designed for

Mixing the two will give poor sound quality and can damage either the amp or the speakers. I had effectively the same issue on my 928 where an aftermarket head unit had been installed which bypassed the factory amp. The 2 ohm rear speakers were absolutely fecked and sounded awful as a result.

I’d check and see if the amp install is done correctly, if it is I’d be tempted to throw in some aftermarket speakers

[A993LAD]

The Wookie said:

Not sure about the 993 but I know 928s have speakers with a different resistance to the common 4 ohm that your aftermarket amp will probably be designed for

Mixing the two will give poor sound quality and can damage either the amp or the speakers. I had effectively the same issue on my 928 where an aftermarket head unit had been installed which bypassed the factory amp. The 2 ohm rear speakers were absolutely fecked and sounded awful as a result.

I’d check and see if the amp install is done correctly, if it is I’d be tempted to throw in some aftermarket speakers

Cheers. I think the amp was professionally installed and the system works ok with it at the moment, albeit I don't think the current speakers are that good.

But my issue is wanting to clear the amp out because it fills my limited storage space plus getting rid of the amp related cables which are huge braided things. There are 10 of these amp wires and each wire to/from the amp is about the diameter of 10 normal wires. I reckon they are also about 3 times longer than required and instead of cutting them to length all the excess is wrapped up in tape and looped up all over the place behind my dash!

With the suggestion that the Becker might work without the amp I want to jettison the amp and remove all of these wires. I'll then wire the existing speakers straight into the head unit and see what it sounds like. My guess is the Becker was previously working without the amp. I bought the car from a record producer and I expect he was often listening to stuff when driving it between his studios in both London and Suffolk which is why he had the amp installed. I know it had some big speakers behind the seats which he took out before I collected the car.

I've been wanting to get rid of this amp since I bought the car 10 years ago as not only does it take up valuable space but also makes it tricky to access the battery/spare wheel/toolkit, but have decided to finally tackle it now as I'm under the dash to remove the aftermarket alarm system (don't get me started!) and horrified by the birdsnest of amp related cabling. Time to bite the bullet.

[BlueMR2]

I don’t see why you cant remove it.

Just remember to disconnect the + or remove the fuse at the battery before you disconnect anything, you don’t want that touching the bodywork live.

Also the original speaker wires may have been removed, so you may have to rewire them into an iso plug, the current wires will be too thick to go in the plug. Also if they are components with a crossover, then you will have to bear that in mind when you rewire as the amp may be controlling frequency’s to stop the tweeters being damaged depending on how many speakers you have.

Edited by BlueMR2 on Tuesday 18th October 13:18

[The Wookie]

A993LAD said:

Cheers. I think the amp was professionally installed and the system works ok with it at the moment, albeit I don't think the current speakers are that good.

But my issue is wanting to clear the amp out because it fills my limited storage space plus getting rid of the amp related cables which are huge braided things. There are 10 of these amp wires and each wire to/from the amp is about the diameter of 10 normal wires. I reckon they are also about 3 times longer than required and instead of cutting them to length all the excess is wrapped up in tape and looped up all over the place behind my dash!

With the suggestion that the Becker might work without the amp I want to jettison the amp and remove all of these wires. I'll then wire the existing speakers straight into the head unit and see what it sounds like. My guess is the Becker was previously working without the amp. I bought the car from a record producer and I expect he was often listening to stuff when driving it between his studios in both London and Suffolk which is why he had the amp installed. I know it had some big speakers behind the seats which he took out before I collected the car.

I've been wanting to get rid of this amp since I bought the car 10 years ago as not only does it take up valuable space but also makes it tricky to access the battery/spare wheel/toolkit, but have decided to finally tackle it now as I'm under the dash to remove the aftermarket alarm system (don't get me started!) and horrified by the birdsnest of amp related cabling. Time to bite the bullet.

Yeah there's not a lot of room in most Porsches of the era to fit it all

I installed a Porsche classic head unit in my 928 and actually managed to find a compact 4 channel amp that fitted perfectly into the space of the OEM amp by the passenger seat, I also had some spacers 3D printed for the rear speakers and put some decent Focal components and hid the crossover boxes in the pointless cubby between the rear 'seats'.

Even in a bigger car like the 928 it was pretty fiddly and I did it all with the carpets out but the results are great, the stereo sounds fantastic and it looks completely OEM.

For the effort you're going to go to pulling all of the wiring out it's worth at least considering whether there's somewhere you could relocate the amp to, few audio installers do a nice tidy job but it can be done. Particularly if you can find a decent compact amp, they're not a fortune.

Worth paying attention to the post above that mentions the pre-outs which were used in the contemporary DSP option that few cars actually had. if your install used the speaker outputs from the head unit then you can immediately knock two wires out of the equation by getting an adaptor to use them with coaxial RCA leads, although the connectors will probably take up a little bit of space behind the dash. Probably actually more of an issue in the 928 with the huge transmission tunnel running under the centre console.

That said I can understand if you're not bothered about that all though, particularly in a convertible 993 and most head units are perfectly fine with a half decent set of speakers. Worth just checking out the speaker impedance against the head unit though, as it will sound crap or kill them and then sound very crap!!

Sympathise with the alarm though, the dealer fit one on my mum's 993 C4 cab has started to die and I'm not looking forward to replacing it!! I should probably consider doing the one on the 928 before I put all the interior back in too.

[Craig f]

From my days of installing these, if I remember correctly.

First off disconnect the battery, the big red cable is going to be your main power feed, trace that cable all the back to the battery and remove.
The Black wire is earth and chances are its bolted to somwhere on the car, again trace and remove.
The blue wire is the switched remote, disconnect this from the amp, it will go back to the becker unit.
The other cable with phono connections will be your inputs, again this will go back to the becker unit.

If the installer was a professional they would have removed the door cards and any panels and run the speaker cables from the amp to the speakers. If so hopefully your original speaker connections should still be in situ, and its a case of reconencting them.

Pull out the becker unit and disconenct the phono leads and switched remote, make sure the switched remote is isolated as it sends voltage when the radio is switched on and will short if not isolated.

there should be a cable thats just hanging around or taped up which matches the slots in the back of the radio, this will be the speakers connector.

With all the cables removed, the switched remote made safe, and the speakers connected reconnect the battery, and test.
Robert should be your mothers brother.

[A993LAD]

Craig f said:

From my days of installing these, if I remember correctly.

First off disconnect the battery, the big red cable is going to be your main power feed, trace that cable all the back to the battery and remove.
The Black wire is earth and chances are its bolted to somwhere on the car, again trace and remove.
The blue wire is the switched remote, disconnect this from the amp, it will go back to the becker unit.
The other cable with phono connections will be your inputs, again this will go back to the becker unit.

If the installer was a professional they would have removed the door cards and any panels and run the speaker cables from the amp to the speakers. If so hopefully your original speaker connections should still be in situ, and its a case of reconencting them.

Pull out the becker unit and disconenct the phono leads and switched remote, make sure the switched remote is isolated as it sends voltage when the radio is switched on and will short if not isolated.

there should be a cable thats just hanging around or taped up which matches the slots in the back of the radio, this will be the speakers connector.

With all the cables removed, the switched remote made safe, and the speakers connected reconnect the battery, and test.
Robert should be your mothers brother.

Excellent thanks. External amp and cables now removed. Identified the original speaker wires and just awaiting some bullet connectors to join them to the Becker speaker plug.