Dad Posted March 29, 2012 Report Share Posted March 29, 2012 Ok, here is the dilema, and search on SQC sucks. can't search 4 ohm lol Any way My 87 shetland has a good stock stereo and i want to keep the stock look but replace the rear speakers and the door speakers, disconnecting dash speakers. not looking for a screaming system just a nice sound that a stock system can give. I was told it is 8 ohm speakers and if I go 4 ohm i could blow the unit, 8 ohm are hard to find. found cheap replacements at auto zone that say are compatible with 4-8 ohm. would like to do a bit better- anyway I took a rear speaker- looks original with the mitsu logo and it measures 4.0 ohms.. and a door speaker measured 6.1 ohm, 88 service manual tells me the speakers should measure 4 ohms. Now of course I am confused,, anyone have a suggestion on what replacements I need to get? 4 ohm? 8 ohm?tryting to get this car ready for PF12 Dad Link to comment Share on other sites More sharing options...
Ofromda860 Posted March 29, 2012 Report Share Posted March 29, 2012 (edited) I have 4ohm Pioneer's all around on stock deck, sounds good to me. One of the first things I did when I bought the car.. Not into the boom, boom anymore! NEVER thought I would say that, lol! This is some good info if you are interested, I'm a car audio fan... http://www.turnswitch.com/speakers.htm Edited March 29, 2012 by Ofromda860 Link to comment Share on other sites More sharing options...
ucw458 Posted March 29, 2012 Report Share Posted March 29, 2012 Front speakers are wired in parallel. (door + dash) 4 ohm speakers would mean 2 ohms to the front channels at the deck. Parallel wiring decreases ohm load while series increases. The OEM front speakers were 8 ohm so the stereo saw a 4 ohm load. Having said that, I've had 4 ohm speakers in my SQ for years with no ill affects. Link to comment Share on other sites More sharing options...
Tman Posted March 29, 2012 Report Share Posted March 29, 2012 randy i may have been wrong but im sure i read that somewere about the 8ohm setup and on one of teddys cars aftermarket speakers burnt out one of hes channels or maybe a quinkedink who knows but when it happend thats when i looked into the whole stereo thing just trying to help Link to comment Share on other sites More sharing options...
techboy Posted March 29, 2012 Report Share Posted March 29, 2012 The only reason that the unit could blow would be b/c of the increased current due to less overall resistance. We all know as resistance decreases, current increases. So, if you can't find 8 ohm replacement speakers, go with the 4 ohm, hook them up and see if you can get a current reading w/ a DMM. I don't know what the amp ratings are on the stock headunit for current, but I'm sure the FSM has them. Then you can be sure your amperage is within spec b/f leaving them installed permnantly. Link to comment Share on other sites More sharing options...
mstieg Posted March 29, 2012 Report Share Posted March 29, 2012 Get Burton on here. He'll shore this up. It's been a dozen years since I messed with my car stereo stuff. I remember that car audio is typically 8 ohm, and I also recall that using 8 ohm on your home stereo is bad for the speakers. They'll work inside, but it's hard on the voice coils since they'll be getting more amperage than designed for. Using 4 ohm in the car may/may not hurt the deck, but I'd think you wouldn't be getting the most efficient sound out of them in the least since they're made for more amps. I'll close my trap and wait for a reply to confirm/refute this... Link to comment Share on other sites More sharing options...
Komeuppance Posted March 29, 2012 Report Share Posted March 29, 2012 Haha... car audio is almost always 4ohm, besides competition/component speakers. The dash speaker is 8ohms and the door speaker is 4ohms, connected in parallel you'd get 6ohms... which is what you measured. You are on the right track, disconnect the dash speakers and use 4 ohm speakers in the doors and in the rear. -Robert Link to comment Share on other sites More sharing options...
Dad Posted March 29, 2012 Author Report Share Posted March 29, 2012 Door speaker is out of the car on a bench, read 6.1 ohms. I appreciate it guys looks like I'm headed to best buy this evening. Dad Link to comment Share on other sites More sharing options...
Burton Posted March 29, 2012 Report Share Posted March 29, 2012 (edited) Get Burton on here. He'll shore this up. It's been a dozen years since I messed with my car stereo stuff. I remember that car audio is typically 8 ohm, and I also recall that using 8 ohm on your home stereo is bad for the speakers. They'll work inside, but it's hard on the voice coils since they'll be getting more amperage than designed for. Using 4 ohm in the car may/may not hurt the deck, but I'd think you wouldn't be getting the most efficient sound out of them in the least since they're made for more amps. I'll close my trap and wait for a reply to confirm/refute this... Actually, most home audio is 8ohm and most car audio is 4 ohm, at least, that's the way it was in the 90's when I was big into the car audio. Here's my take on the funky front reading... Due to the way they are wired, with the dash being an 8ohm and the door being a 4ohm. 2 8ohm speakers would show a 8ohm load, and 2 4ohm speakers would show 4. Since you have different load speakers, you will end up with the sum resistance of those speakers, which would put you in the neighborhood of 6ohms. Anyway, I could go on and on about different resistance speakers and different methods of wiring to tweak the ohms load the deck/amp see, but that would take all day LOL. IMO, the only time the 4ohm VS 8ohm argument matters is when you're talking about running high power equipment. Some little full range speakers on a 20W deck will be no big deal no matter how the ohms load changes. If you're talking about a 1000W subwoofer on a 1500W amp, then you want to make sure you have your ducks in a row. In my days as a car audio installer I probably swapped out hundreds of OEM speakers for aftermarket units, and all of the ones I put in were 4 ohm. Some of the OEM stuff was 6ohm, and a small amount of it 8ohm, but most was 4ohm. I can't recall any of them that came back because they caused the deck to blow. I'd throw some 4 ohmers in there and be done with it. Edited March 29, 2012 by Burton Link to comment Share on other sites More sharing options...
mstieg Posted March 29, 2012 Report Share Posted March 29, 2012 haha - had 4 & 8 backwards. Told you it's been a while! Link to comment Share on other sites More sharing options...
Dad Posted March 30, 2012 Author Report Share Posted March 30, 2012 Thank you guys! you are the greatest. Picked up a set of pioneers today- hope to get at least the rear two in this weekend. Dad Link to comment Share on other sites More sharing options...
The Rabbit1 Posted March 30, 2012 Report Share Posted March 30, 2012 (edited) two 4 ohm speakers wired in parralel read 2ohm load, in series they read 8ohms, basic ohm's law: http://www.caraudioh...aw/ohms_law.htm Edited March 30, 2012 by The Rabbit1 Link to comment Share on other sites More sharing options...
Chad Posted March 30, 2012 Report Share Posted March 30, 2012 two 4 ohm speakers wired in parralel read 2ohm load, in series they read 8ohms, basic ohm's law: http://www.caraudioh...aw/ohms_law.htm yes, and 2 8's in parallel is 4. Thus if you remove 2 8's in parallel and put in a single 4, the deck never knows the difference. Here is a site with an online calculator, you have to use inverses to calculate, so it's not always an easy guess when you mix different values. http://www.sengpielaudio.com/calculator-paralresist.htm Does the speaker have the ohms stamped on it? pretty sure most of them do that I've taken out, just very faint. If you put a 6 and 8 in parallel, the 6 will receive the most power, and I really doubt that was the goal with those tiny dash speakers. That low reading may be due to coil insulation breakdown. It may also be due to the inductive reactance of the coil, it's an inuctor, not a resistor, so it has a resistance responce that is porportinal to frequency. DVOM's pulse out a sample voltage at a set frequency, and this frequency alters the resistance measurement on a coil, especialy smaller ones. You are measureing the coils inductive reactance in adition to the linealr conductor resistance. It makes Ohm readings unreliable [though usualy very close]. Link to comment Share on other sites More sharing options...
Dad Posted April 2, 2012 Author Report Share Posted April 2, 2012 Thank's guys! I'm real pleased with the pioneer speakers, had to dremel some of the plastic for the rears but still retained the stock speaker covers, disconnected the dash speakers and installed pioneer door speakers. They sound great with the stock system. pioneer rear speakers 6.5" # TS-G1644R and fronts 5-1/4 TS-G1344R Dad Link to comment Share on other sites More sharing options...
Leeintheconquest Posted April 4, 2012 Report Share Posted April 4, 2012 Is the stock size for the rear 5.25" or 6.5"? Link to comment Share on other sites More sharing options...
Ofromda860 Posted April 4, 2012 Report Share Posted April 4, 2012 Is the stock size for the rear 5.25" or 6.5"? Rears are 6.5". Link to comment Share on other sites More sharing options...
ucw458 Posted April 4, 2012 Report Share Posted April 4, 2012 I still run dash speakers. You get alot of sound from them. Link to comment Share on other sites More sharing options...
Tman Posted April 4, 2012 Report Share Posted April 4, 2012 I still run dash speakers. You get alot of sound from them.ditto Link to comment Share on other sites More sharing options...
The Rabbit1 Posted April 6, 2012 Report Share Posted April 6, 2012 I still run dash speakers. You get alot of sound from them.dittox3 Link to comment Share on other sites More sharing options...
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