View Full Version : New Pre-outs on 99-02 Ibiza
AliBaker
24-04-2002, 17:04
Ok so everyone must know that the Ibiza has no 2-4v line outputs right, well during the summer a friend and i have a project on, to figure out the circuitry inside the headunit. and to add in the some cables from the pre amp output stage to feed my amp. Shouldn't be too much of a strugle.
Now before i do this i would like to get hold of another Headunit from SEAT (just the metal box) to work on (just in case something goes wrong).
I NEED A PRICE FOR THE HEADUNIT (1.8 20VT CUPRA)
When all is done i will have 2 finished products,(mine and the working spare) would anyone else be interested in purchasing the spare one (complete with the F+R PreOuts??)
Should be relativly easy to do mate.. I've got the circuit daigram for the leon Aura head unit and it would be a fairly trivial task to add the preouts to that Just pick um up off the output of the mixer chip. In the Aura its a TDA7340G
Pin 23 is Right Rear
Pin 24 is Left Rear
Pin 25 is Right Front
Pin 26 is Left Front
According to the data sheet This will give you 2V preouts sitting on a DC offset of 3.8V.
These signals are all with reference to vehicle Ground though so you have to make them differential after this.
Good Luck
:cheers:
m
I would definitely be interested. I've recently just installed 2xHigh/Low Level converters on the speaker outputs from the head unit to allow me to run my amps.
Although i am quite impressed with the quality i am getting there is a very faint sound of whining at very low volumes. Once turned up though you can't hear any different, but it would be nice if possible to lose all traces of the interference.
If the proposed output from the modifed head unit would be 2v you could run this into a Professional Line Driver and increase the voltage upto 4v before sending the signal down the car to the amps. Giving you a better quality signal and pretty much guarantees no signal interference.
Adam
Pete looked into this for me
Audiobahn do a line driver with speker level inputs.
ALD28X £90
www.audiobahninc.com
Or alternatively in the single ende to differential conversion your mate could add a x2 gain stage:D
m
Atually anybody that maybe interested in doing this I have the perfect tool for the job - Phenix Gold PLD1 - pro line driver 4 v Output , they dont get any better than this I'll add it to the list on " For Sale " section.
I think u guys missed the point... I'm pretty sure Ali was after the signal from the head unit before its gone through the scabby speaker drivers in the head unit. He was after adding pukka preouts rather than just converting the speaker level back to line level.
I may be wrong it wouldnt be the first time:) Thats just the way I read it. IMHO pukka preouts will beat the ass off of any speaker to line level convertors for quality if its done the right way:D
m
Originally posted by Crofter
Atually anybody that maybe interested in doing this I have the perfect tool for the job - Phenix Gold PLD1 - pro line driver 4 v Output , they dont get any better than this I'll add it to the list on " For Sale " section.
ive got a PLD1, though for an application in an Ibiza 20VT this wouldn't be of any use, cause the intergrated stereo can't accept RCA inputs or outputs, so the one as Saul has said that Pete found is more useful as it has speaker outputs.
If you have a replacement headunit as i do in the Leon then the PLD1 is a good buy.
AliBaker
26-04-2002, 12:26
Cheerz matt1e
Please don't miss the point. no matter how you try to "convert/condition" the signal to the input of an amp you will still loose acuracy in the low frequencies, especially with a matching transformer!!!
Unless these line drivers have a fairly complex DSP which i doubt. then i would doubt their bass response would be compareable to the newly wired pre-outs either
Also you would really need to load the headunits amplifier with about 4-8 Ohms to get the best signal response, and still a matching transformer or a line driver will not do this!!!!!!
Pre-outs would VASTLY improve the signal,
I'm not sating that line drivers arn't good, but if you like your bass to thump with more accuracy (if you listen to music with a real kick drum for instance not synthesized) you're best off with pre outs.
Yes however if you do tap into the circuit bring out two line level out puts ( Not after they have been through the internal amp , but before ) then you will have a relitivly low signal out . Using a PLD1 at this point would then boost the signal up to 4v there for perfect for what your planning.
AliBaker
26-04-2002, 12:56
But....
The idea is to put a circuit inside the unit, its nothing to complex to get the signal to 4v p-p. then there will be, four/six rca outs, also was thinking of putting a remote cable out too, so the Original cables don't need to be altered.
as mentioned 5/6 rca outs maybe available,2xfront,2xrear + 1/2 for a low pass filter for simple sub set ups. (with a steup knob for freq select located at rear??)
any other ideas whilst the box is open???
The remote is easy mate as the main witch panel uses a resistor chain I have an old front panel that I can rip the values from:D
I agree just a simple amp circuit to get from your 2V p-p comming out of the preamp chip will give you differentail outputs at 4vp-p.
Excuse me for my ignorance but why would you need any more than two ch out of the stereo ?:)
AliBaker
26-04-2002, 13:39
If for say you wanted to put a stereo amp on the rear speakers and a stereo amp on the front speakers and a monobloc/stereo amp for the sub,
hence 5/6 outputs
The fader on the head unit will be able to still fade front to rear amps.
Also the sub woofer signal could be the left and right signals integrated. also faded on the Rear O/Ps
but it is at this point I dont understand , before amp stage internally there will only be left and right , I imagine that the fading stage will be done at the amp stage , when controling the bass / trebble control this would effect not only your front and rear outs but also this control I imagine will effect your dedicated 5th and 6th ch. out.
:(
AliBaker
26-04-2002, 14:00
1 Signal soure CD/Tape
2 EQ bass/trebble
3 Mixer balance Left to Right
4 Fader Front - Rear
5 4x monobloc amps.
This is the logical order for the circuit layout. to fade the signal after using just a 2ch amp would need a Digitally controlled High power rated pot. And as all of this is done inside an IC this would be a lot more expensive than using 4x power amp circuits.
So after stage 4 there will be 4x 2v signals to play with, FR FL RR RL.
Put these ou the back of the box and there you go.
SUB OUT....
take the RR+RL combine the signals using another preamp circuit (so as not to combit the regular RR+RL) and put a low pass filter on it, then hang that out the back too.
Is that what you mean??
Yeah, i was only posting about the line driver cos u said u were goin to get 2v pre-outs, which would be too low, but if ur goin to increase to 4 then theres no need.
Im looking into puttin a DIN unit in the dash, watch this space.
AliBaker
26-04-2002, 14:23
SAUL...
Cool,
Make sure you do keep us posted I'm sure everyone is interested to see one done. So they can see it infront of them, Not just photos.
Cheerz
Ali your obviously a lot more tech minded than me :( Im one of the old school - Front and sub all you need kind of guy.
The way I'm setting up my system will only use the existing stereo for the CD conrols and using a dash mouned pre amp connected directly to the auto changer to conrol volume ( Fader if you wish ) ,balance , EQ ect .
Cheap and cheerfull :D
I've converted a front panel for a din conversion already.. I dont have a beeza but I got a warrenty return dash... Its all looks spankin I just need someone to see if the head unit will fit into the dash void in the position I have chosen....
The TDA7340 IC controls the front to back and left to right... if you l;ookat the data sheet you can see a block diagram...
m
AliBaker
26-04-2002, 15:07
So how many people are interested in having their current stereo adapted to have preouts????
It would be made to order, with 2(Rear) or 4 (Front and Rear), or 6 (Front Rear and Sub) 4v or 2v. options
state your spec...
what would you spend???
thanx for the interest
I would definitely be interested with either 4 or 6 pre-outs each supplying a 4v signal.
What sort of price are we looking at???
AliBaker
29-04-2002, 13:12
What would you be prepared to spend, 50-100?
more - less?
be reasonable, think what its goning to take us to develop then do the work for each unit
I think £50-100 is a reasonable price to ask, depends what exactly is involved, whether its mostly labour or are there some expensive components that would need to be purchased for each conversion.
As i've said already, i've just installed some converters which although do the job well, do give off a small amount of interference at low volumes. I don't particularly want to start hacking my dash apart just to fit a din sized head unit, for security and re-sale reasons.
So to have some pre-outs from the standard head-unit i think would be very interesting to a lot of people on this forum.