Well, that didn't work....

[defblade]

...... and I don't know why

I'm pretty good with ICE as a rule, came up with a cunning plan to fit my aftermarket HU instead of the Concert one (A6 Avant, 2001, non-BOSE). I wanted to keep the sub and amp, but switch the amplification to the fronts to get some staging.

So I got the adaptor for the plugs that includes RCAs -> the amp plug and the remote wire. Then I ran a bunch of speaker wires down the car, and cut into the amp output wires going to the rear speakers. I gave the rears a feed from the HU by joining the new wires to the speaker-side of the cuts, and took the amp output to the fronts from the amp-side of the cuts. The rears came on fine (powered by HU), so I know I got the right wires from the amp.

I then plugged the RCAs into the front pre-outs of my HU and expected to get the sub and fronts come on. No such luck - nothing. The red plug on the sub is getting remote live and permenent live. I've also tried the rear pre-outs, both front and back at the same time, and even the sub pre-outs. Not a sausage.

I've rewired the fronts to the HU for now, so I've got a bog standard, no subwoofer system running at the moment.

Only thing I can think of is if the pre-out voltage on my HU is too high for the OE amp??

Otherwise, I just can't see why this isn't working - even if my new wiring to the front speakers was dodgy, should still have got the sub playing....

......any ideas folks?

 

[AndyMac]

What HU are you using.
Also the amp in the new HU is almost guaranteed to be better than the Fisher Price garbage Audi fit, so I'd recommend you stick with running all the cabin speakers off the HU. The Audi amp is only 2 x 20w so will be unbalanced with the rears anyway.
The RCA adapter is wired for both front & rear but the stock Audi rear amp loom is only wired for the rears, so you can only use the rear RCA's on the adapter. The front RCA's on the adapter are wired to nothing. So I'd stick with all speakers running off the HU, then plug the sub pre-out from the HU into the rear RCA input on the adapter, to feed the stock sub. Depending on the HU you have you'll need to switch on the sub pre-out as most HU's ship with the sub out turned off (look in the manual on how to do this).
You'll then really need to jack up the level on the sub pre-out to get anything coming out of the sub amp as it is only 1 x 50w and will struggle to compete with the 4 x 50w going to the cabin speakers.
Personally I'd ditch the stock sub/amp, buy a cheap Alpine V12 1x 200wrms amp (bridged) on ebay (they go for around £60) then run new power from the battery for the new amp. Build a small MDF enclosure to fit in the lefthand cubbyhole and use this to mount a JL Audio 6.5" sub. You'll need to chop the back off the cubbyhole to give you enough room. Then run a pair of RCA's from the HU sub pre-out to the amp and sit back and enjoy the transformation.
If you don't fancy all that work then simply by pass the Audi amp and install a small 2ch amp to drive the stock sub properly. The Audi amp is underpowered to start with and for some reason is even less powerful when used with an aftermarket HU even when using 4v+ pre-outs which are way better than the stock HU.
Here's my install in our 01 B6 Avant and it sounds fantastic.

 

[defblade]

I've got a genesis profile 2 and a dragster da602 amps in the workshop, but very little time to do anything near a proper install at the mo Looking at gene profile 16s in the front and a Hertz energy 8" sub in the LHS (they run tiny enclosures) much like your set up... but no time!

Found a list for my actual HU rather than the restyled one.

Hoped what I did would be a quick fix but no such luck. I never considered the HU amp might be better than an external, but then I only buy decent externals Might be worth trying the sub preouts but I'm still not sure why I got nothing at all from the OE amp last night....

 

[AndyMac]

Probably because you were plugging into the front section of the adapter, which isn't wired to anything. Only use the rear RCA's on the adapter, and you'll need to whack up the signal to hear anything.
I've got a Hertz Energy HX200 as well, been meaning to give it a try, it's a beast of a sub, weighs a ton!

 

[defblade]

The adaptor only feeds the RCAs (it has 4 of them; they share an earth before they reach the plug and merge the front and rear live wires on each side) to the correct wires for feeding the OE amp. I've double checked the connections with the Audi wiring diagram to make sure it's all hitting the right connectors. Upshot is pluging either pair of RCAs into any set of plugs on the back of the HU should send a signal to the amp.

Anyhow, had a brainwave-ish and think I'll see what size aftermarket active sub (like maybe this) I can fit into one side of the boot or the other as it's only a bit of bass I'm after now. I know I've got live, earth and remote all working back there anyway for the OE amp, so nice and easy. I was worried for a sec about wire gauges but then realised I've already got 200w coming off a similar or possibly even smaller wire in the front so so long as I keep it to one of the 150/200w models, should be easy. Famous last words I know it's not very SQ but should do for now.

 

[defblade]

Success! Wired my OE sub into one of the rear speaker wires and it plays just fine!

Cut into the white+white/brown pair and tapped them into the same connector. Did it with the rear speakers disconnected first just in case of trouble, plays fine with them back too

Oh, still used the adaptor but only for the remote signal.

This means that I'll only be getting the bass track from one channel, but I think I'll live compared with spending £100-150 and the hassle of running RCAs and wiring in an active sub until I get around to a full install (moving house in about 3 weeks, so don't hold your breath ).

 

[DrNo]

Glad you got yours sorted. I'm having similar problems with the RCA connecter and pioneer HU so am trying to work out exactly what it is you've done so I can try it. Do you mean by wiring your OE sub to one of your rear speaker wires you've not used the amp at all? I assume you have the same amp as me (ie seperate one behind the rhs boot trim) - which are the wires for the rear speakers and the sub (which side is white&white/brown for)? Did you just snip them all at the amp connector and then wire them up to the new wires you had running from the HU? Sorry for all the questions but don't want to fry anything!

 

[defblade]

Colours at sub plug are (for my '01 A6 avant):

pin#: wire colour:description
1:red/blue: +12v perm
2&3: blue/green and brown/red: +ve and -ve for rear left speaker (output from box)
4: brown: earth
5: white: remote live feed (mine had extra length on this wire under the wrapping)
6: white: a twisted pair with one of pin 8; rear left +ve signal input
7: yellow: twisted with 8 again; rear right +ve signal input
8: brown/white: two wires; input signal commons.
9&10: red/green and brown/black: rear right ouput +ve and -ve


So, I've connected the adaptor plug with the blue wire to the remote out on my HU; ignored the RCAs.

Then wired fronts into the OE wiring from the HU via the appropriate adaptor.

Then connected 2 looong speaker wires to the HU rear speaker wires. Run these under the dash and along under the sill trims, under the back seat and into the side trim where the sub box lives.

I've then cut into 3 pairs of wires at the sub plug: 2&3, 9&10, 7 (yellow to sure you don't get the wrong white) and one of 8.

Tape up the wires coming from the plug for 2&3 and 9&10 and from the loom for 7&8.

Join one new speaker wire pair to 2&3 going into the loom and off to the speaker.

Join another new speaker wire pair to both 9&10 going into the loom and 7&8 going into the plug. So you will have +ve from HU, yellow and red/green joining and -ve, brown/white, and brown black joining.

One new wire is now connected to the rear speaker, the other is connected to the other rear speaker and the sub signal input. The sub is no longer connected to the rear speakers.

I've no idea if you could connect both speaker cables to the sub inputs (so not lossing bass if it's on the unconnected channel only during a track); I suspect that the HU would get upset at getting a common earth as I believe high power HUs these days drive a signal both ways down the wire; if you want to risk your HU amp, feel free to try

I'm hoping I don't have to mention being very careful with signal polarities at every step??

Any other Qs just ask

FWIW, the sound isn't going to win prizes, but I have really missed the bass for the couple of weeks it's taken to sort this out. It's reasonably balanced now, enough to be going on with

 

[DrNo]

Thanks for the explanation, unfortunately I think I've got a different set up - my amp has a 23 pin connector which I've just managed to find a diagram for so tomorrow am going to wire up the rear speaker outs from the HU to the rear speaker outs from the amp, so bypassing it. Came across a thread on another forum which might explain the problems we (and a few others) have had with no/little output from the rears and sub:

Q: I am having a problem with the rear speakers in my 2001 audi a4, the
front speakers seem to be fine but the rear speakers seem to play at a
very low volume also I do not think the rear sub woofer is working.

A: If you've got an aftermarket head unit fitted, this is probably
because of the interface. The Autoleads interfaces in particular have
a low sensitivity input, so unless the head unit has high voltage
preouts, the rears tend to sound fairly quiet. To overcome the
problem, you can bypass the amps, or fit a line-driver between the
head unit and interface.

(explanation courtesy of Jon at In-Car Express) Apparently, Celsus do a line driver which costs around £25. I'm going to try the adapter which doesn't use the RCAs first to run the amp and sub and if that doesn't work will try the line driver.
Cheers

 

[defblade]

The Autoleads interfaces in particular have
a low sensitivity input, so unless the head unit has high voltage
preouts, the rears tend to sound fairly quiet.

My HU has 4v preouts, which is pretty high, but I got nothing at all, not just quiet. However, sounds like there's a lot of different variations around - the highest number of pins on a plug in my OE stereo is 20...... good luck!

 

[AndyMac]

The Autoleads RCA input adapter is purely a straight through wiring adapter, no electronics, so it can't introduce a low sensitivity input. The speaker input adapter is what they're talking about as they recommend its use only with a high pre-out voltage HU.
I had the same issue on a Blaupunkt DAB HU which uses the same mini ISO pre-out connector as the stock Audi HU, so no adapter needed. It's a combination of the high input sensitivity of the stock amp and the fact the amp is under powered to start with.
If you get nothing at all then are you sure you've connected the remote on wire to turn the amp on?

 

[DrNo]

Finally got round to wiring my rears up direct - surprisingly easy as well once I'd sussed out which wires to snip on the amp. Still nothing from the sub though - was hoping it might have miraculously started booming...Checked the blue wires from the rca adapter, antenna amp and remote from the HU and all are securely connected but in the pioneer installation manual it says:
The pin position of the ISO connector will differ depending on the type of vehicle. Connect 6 and 7 when pin 5 is antenna control type. In another type of vehicle never connect 6 and 7.
Not sure what this means but as I've used the adaptor I guess it's not relevant in my case?
In fact the sub which was just about producing something audible at first decided a few days to quit completely. I'll hopefully be trying the non-rca adapter this week - will let you know how it goes.