I read in a car stereo magazine some years ago about a competition car that used the Delco CD player as the headunit and where it had been converted to a preamp only setup to provide cleaner signal to the amps in his system. Has anyone here tried this or does anyone here have an idea of how to do this? Then possibly run the signal through a line driver to boost the voltage to at least 4 volts for a clean,strong signal. I thought it would be interesting to use a 4th gen CD player from a T/A for this. Anyone?

 

The newer Delco units (97 or 98 and up) can be used as part of a very good stereo if a good Line Output Converter is used. I'd suggest a David Navone unit from www.davidnavone.com. His are considered some of the best. Keep in mind that any competition-level system that uses a factory deck is likely to need some external equalization to offset any internal equalization used in that head unit. The new Cleansweep unit from JL Audio might be the ticket, or you can use the LOC in combination with a standard equalizer.

Any deck that's older than the 97 or 98 model is a waste of time and should be avoided.

Also keep in mind that some of the newest Delcos have an EQ curve that changes with the volume. Overcoming something like that will be nearly impossible and would be better off just being avoided all together. I know the stock Cadillac CTS stereo does this, but I suspect that plenty of others do also.

 

Thanks for the info. Do you know which Delco CD decks would be preferable over others? Also, do Delco CDs play CDr discs?

 

I got curious as to what the cleansweep actually was so I looked around and found this thread. It might very well be part of the future of car audio as more and more cars have their stereos integrated into their dash.

Aside from the eq curve shifting with volume in some newer units as Jim mentioned, some units also adjust volume for speed (they will increase/decrease volume to compensate for road noise as you change driving speed). Odds are you would want to avoid one of these units as well.

When I first read your post, I didn’t even think in terms of the newer (98+) model units. I thought about tearing into an older unit - one that would have come stock in our cars - and then trying to find a diagram that would give you an idea where the preamp circuit and amp circuit connect. That way you could grab signal from the cd player before it hits the internal amp and then run that signal through rca’s to a line driver to get the signal up to a decent voltage and then to an amp. As far as I know/understand, the source of crappyness in the stock units is their poor internal amp. I doubt that their cd player would produce all that dirty of a signal. I could be wrong though

It would defiantly be far cooler to do it with as old a head unit as possible if you can pull that off. I’m tempted to try it myself with an old delco head (1996) I pulled out of a Saturn just to see if it is possible.

 

It can be done, but it's a lot of work and I can't see it being worthwhile with an old deck.

 

The head units with the speed-adjusting volume are actually the ones that you should be looking for. Those are some of the better quality Delco radios out there. You can disable the speed-adjusting volume if you choose not to use it, although I have to admit, that I found it very convenient when using my father's truck. I wish some aftermarket models would employ it.

 

Would a Monsoon unit be a good choice? Which vehicles had the speed sensitive volume and how would you go about disabling it or is it switch activated?

 

I haven't had any experience with the Monsoon equipment, but if that system uses external amplifiers like the Bose system does, it will be easier to avoid it.

The speed sensitive volume has an adjustment right on the main volume ****, and if you turn it all the way down, it eliminates it. Almost all of the regular 1.5 DIN delco radios in the f-bodies, trucks, and probably most other Chevy and GMC vehicles were the same or very similar. Pontiac probably had a similar radio with different cosmetics. Buick might have used it in some models, but most of the buicks went to a unique double DIN radio. Most cadillacs had a different radio.

 

Pioneer 'ASL' and JVC 'Cruse Audio'...

 

How do those work? I remember for a while that JVC had an rpm dependent volume option, but it never seemed to be met with much sucess. Perhaps these new implimentations are a bit more advanced, though I'm not sure how they'd do it without some sort of VSS input.

Though if it was on a pioneer NAV unit, I suppose it could use the GPS data to determine speed.

 

AVIC-N2

JVC isn't doing it any more, but you're right, it was RPM dependant. Used an AC coupled amp right off of the B+ input, then a high gain op-amp, there you go, RPM signal. Didn’t work all that great.
Pioneer uses a mic on the main PCB that runs back into the EVTC IC, “filters” the music and use that. It’s not bad, but not great. It has like 3-5 ‘levels’ of correction. It seems to depend on the vehicle as to how well it works. Works great in my truck (94 Sanoma), but like crap in the IROC. In the car the radio is to close to the floor, gets to much road/engine noise from behind the dash. There's to much noise back there for the radio pickup the ‘real’ cabin noise and work right. In a 2003 Saturn it worked even better then the truck. So it seems the quieter behind the dash, the better.

Edit: How's the JVC doing?

 

It's pissing me off. I gave up and sent it out for repair along with the dvd player. I got it back saying that nothing was wrong, and voila! It works now.

But... since I reinstalled it, I noticed that it's got a ridiculously high noise floor. I have no idea why I never noticed this before. Either way, I had to back off so far on my gains to eliminate it that now I can't reach full output on my amps.

I'm keeping my eyes open for a Rockford 8250, but those things have been going for unreal amounts of money on Ebay lately.