SpEeD147 Posted December 11, 2009 Report Share Posted December 11, 2009 so my dad and i are debating whether or not to upgrade our 84 conquest's sound system with 6 new speakers (yes, including the dash speakers surprisingly), an external amp, all while using the STOCK head unit. So i'm trying to figure out what impedance the stock system is running at, I've heard 8 ohms and 4 ohms... Scouting around the forums and service manual I've come across somewhat conflicting information and im slightly confused. The 84 service manual says the dash speakers and door speakers are wired in SERIES...whereas the 88 service manual says they are in PARALLEL...okay. i believe the speakers that are in this car are stock although i am not sure if they are stock for this car...(could be 88 speakers or something dumb like that, but the speakers are stock conquest...this is something that could be the problem). Looking on the back of the rear speakers and the speaker in the dash (near glove box...assuming other speaker near cluster is the same) all say 4 ohm impedance. So i put a ohmmeter up to the rear speakers and i get 7.3 ohms, why isnt it 4? Next i checked the resistances of the speakers right before they entered the head unit...the rears both were 7.3 ohms, which is expected since they go straight to the head unit. The FR+ and FR- pins, as well as FL- and FL+ pins had an impedance of 12 ohms...which means, since in series, one speaker is probably 4 ohms and the other probably 8 ohms. To my knowledge the impedance of the system all-around should be the same, either 4 or 8...not expecting 12. i used this http://starquest.i-x.net/viewtopic.php?t=1109 and the manual to find the correct pins to measure any advice, anything else i need to check? Link to comment Share on other sites More sharing options...
Burton Posted December 11, 2009 Report Share Posted December 11, 2009 (edited) If you're going to be running an amp and replacing all the speakers anyway, the factory speaker resistance is a moot point. Most aftermarket speakers are 4ohm. Also, I wouldn't waste my time with the dash speakers. Either that, or I'd get a component set for the front and put the tweeters where the dash speakers are. Personally, I'd lose the dash speakers, cut the door panel out to accept a 6.5 instead of the 5.25, and use a component set with a tweet mounted high in the door. It's be easier than messing with the dash speakers and will give you better sound. Edited December 11, 2009 by Burton Link to comment Share on other sites More sharing options...
Komeuppance Posted December 12, 2009 Report Share Posted December 12, 2009 83 to 85 cars have the special ETACS unit that plays a melody through the front left speaker. Each speaker should be 4 ohms. The fronts are wired in series to get 8ohms total at the head. You should measure ohms at the speaker, not at the head, because them you have to factor in the length and age of the wire's resistance. It is also a possibility that they are wired as common ground, it would be a good idea to do a continuity test with the ground of the chassis. If you are planning on upgrading, I would leave the dash speakers in, but do not connect the dash speaker wires to the headunit/amp, so your melody will still play when you open the door, but your music will not go through the dash speakers. Then, run new wires to the door speakers, and new wires to the rear speakers from your amp. In an 83-85 SQ:Dash speaker left size: 3.5" or smallerDash speaker right: 4"Front door speakers: 4"Rear speakers: 5.25" You could increase the size of the door speakers to 5.25", and rear speakers to 6" with minimal effort. This is what 86 and up SQ's use stock. Make sure you get an amp with a cross over so you can fine tune your new speakers. -Robert Link to comment Share on other sites More sharing options...
SpEeD147 Posted December 12, 2009 Author Report Share Posted December 12, 2009 If you're going to be running an amp and replacing all the speakers anyway, the factory speaker resistance is a moot point. Most aftermarket speakers are 4ohm. Don't I need to know the resistance as to not blow the stock head unit's internal amplifier out? 83 to 85 cars have the special ETACS unit that plays a melody through the front left speaker. Each speaker should be 4 ohms. The fronts are wired in series to get 8ohms total at the head. You should measure ohms at the speaker, not at the head, because them you have to factor in the length and age of the wire's resistance. It is also a possibility that they are wired as common ground, it would be a good idea to do a continuity test with the ground of the chassis. Yeah we realized the ETACS was needed when the front left side wasn't working, interesting design. OK, i measured the resistance at the rear speakers and got 7.3 ohms for each...which is why im confused because they say 4 ohms on them. But ok so what you're saying is that rear system runs on 4 ohms, and the front 8 ohms which makes sense based on the specs that are on the speakers...isnt a stereo system typically supposed to have the same resistance all the way around? and the reason i measured at the head was because i wanted to see what the head unit is seeing...so i can duplicate that with new speakers so as to keep the head unit safe from damage. or does that not really matter? Thanks, Tim Link to comment Share on other sites More sharing options...
Burton Posted December 12, 2009 Report Share Posted December 12, 2009 Don't I need to know the resistance as to not blow the stock head unit's internal amplifier out? I thought you were going to be getting a 4 channel amp to run your speakers and not use the power from the stock deck? I was assuming you'd be getting knockdown convertors to convert OEM deck power to an RCA lead for the amp, or use an amp that had a high level input. Personally I don't like even using the high level inputs on amps. Using actuall knockdown convertors will give you a bit cleaner signal. Anyway, how did you plan to be using both deck power and amp power to run your speakers? I wasn't aware the earlier model SQs had smaller speakers, I've never messed with anything older than an 87. I still say cut what you have to and get the biggest speakers you can in there. If you got an amp to push some power, you might as well get all the sound you can and go with bigger speakers. That's just me tho, and my trunk and back seat have been replaced with audio, so I usually go as extreme as I can LOL Link to comment Share on other sites More sharing options...
SpEeD147 Posted December 12, 2009 Author Report Share Posted December 12, 2009 I planned on taking the amplified signal from the stock head unit and just amplifying it again with a separate amp. I know it won't be as clean as a line level output but it shouldn't mess up the sound too much. and yes, convert to RCA outs. i think life is just gonna be easier getting a new head unit, and running new wires...the carpet is already out of the car, we just layed some dynamat and yeah, I saw pics of your setup while i was searching around...straight ridiculous lol Link to comment Share on other sites More sharing options...
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