So, we finally got round to trying to fit the amps onto the back

of the standard head unit.

The amps to be used were a Pioneer 2x35W (RMS) unit, and

a Pioneer 2x80W (RMS) unit - not extemely powerful, but enough

to make the setup easier to hear. The lower power sub was due

to go on the back, the higher on the front (in accordance with

speaker quality).

I won't run into too much detail about the loom unless requested.

Basically, into the HU's line out a "yellow plug" to RCA adapter

was fitted. This was then connected to each amp, and the output

from each amp was then fed into an 8 pin ISO connecter, which

fitted into the speaker connecter originally plugged into the back

of the head unit.

During production, testing using the small amp revealed that

the amp had a weak right channel - worked a bit, faded, wiggling

it about brought it back before it died.

So then the line out was bridged such that the larger amp could

be used to power both front and rear. Worked a treat - played

about with volume, balance and gain. This revealed the front

wing mirror tweeters distorted way before any of the other

aftermarket units. Pulled these out, and the sound was spot on.

Putting it all together, the left channel died. Turned out to be a

loose connection. This rectified, the right channel went silent.

Nothing wrong with the wiring - test with a multimeter revealed

the right channel on the amp had gone! Bit more multimeter

testing on the line out revealed that the voltage varied from

high extremes, and far more than would be expected.

Result: two broken amps.

Conclusion: There might be something wrong with my particular

head unit. Testing this might be tricky, as if it is an issue with

the Symphony it will destroy the amp.

If it is a problem with all Symphony units, then the only way

to increase the power of the system is an aftermarket HU.

Thanks to Ian (Tavia4x4) and Paul (ffelan) for their efforts! :cheers:

Rob.

no probs Rob,

hopefully we can have a more conclusive project next week.... I have just tried a std pioneer 2500 single cd with 4x45 amp... in lieu of the std symphony.... it does make a big difference although i quickly found the limits of my speakers... I think your infinity units might handle the power better.....

Well, what I was thinking was to get a head unit with RCA outputs on it. Seems to me most of

the manufacturers' are quoting peak not RMS, so even a 4x50 unit will only be 4x25 RMS - less than

the big amp's output when bridged. So if I get a head unit with outputs, I'd probably still whack the

amp on the back of it if Ian finds out what's wrong with it!

My only dilemma now is...new CD changer (and probably new wiring down the car), or get a head

unit that can play MP3 CDs. Or get a CD changer *and* a head unit that will read MP3 CDs...

Rob.

will lend u the spare pion cd that i was messing with....?

4x45 1x preouts changer controller?

I'm guessing that would need a Pioneer changer to work though?

Though I suppose, if we tested it all out and it worked, I could slip you a few

notes for it and then the changer could be tackled at a later date...?

And hey, I'd have something TVR in the Skoda then!

Rob.

sounds like a plan...

Rob,

found the cheap shop on the web...

was

www.cel-direct.com

pion changer @ 89

Hmm...thay also have a Pioneer MP3 head unit for

bolton...

www.alphacaraudio.co.uk

or 01204 366 386

Cheers Paul - they seem reluctant to quote their prices on the web, so I hope that will work out in a good way!

Rob.

ive just ordered from cel... some alpine gear... let u know how it goes...