dougdrake Posted July 1, 2003 Share Posted July 1, 2003 I know I can count on you guys to know this...(sorry for the length). The question: How can I determine which speaker lead is + and which is - if they are not marked? Background: The factory radio in my car has a factory amplifier installed in the trunk. Speaker level leads run from the head-unit to the amp. I am preparing to install a sub in the trunk, with its own amplifier. I will tap into the leads going to the factory amp to feed high-level inputs into the sub amp. To remove the low bass from the main speakers, I have to install high-pass filters in the speaker leads going into the factory amp (after I tap them for the sub amp). I understand that I need to put all the filters on the same relative lead for each speaker (+ or -). The leads are not marked +/- (you gotta love factory wiring harnesses). However, I believe the speaker posts themselves are marked +/-. Assuming they are connected correctly at the speaker end (I know, big assumption), is it possible to use a multi-meter to check continuity through the factory amp to determine which lead going INTO the amp is connected to the + lead at the speaker? Other suggestions? Doug Quote Link to comment Share on other sites More sharing options...
ben. Posted July 1, 2003 Share Posted July 1, 2003 You can check the leads for continuity, or if you are able to actually see the speaker cone, you could check polarity with any 1.5V (AA, AAA) battery. Simply touch the speaker wire to the ends of the battery. When the speaker cone moves forward, the leads are touching the appropriate +/- ends. Do not do this with any higher voltage battery. You will shred the cone!! This is also useless if you can't see the cone movement. Quote Link to comment Share on other sites More sharing options...
dougdrake Posted July 1, 2003 Author Share Posted July 1, 2003 Good idea. So, just to confirm in my pea-brain. Put the leads on the battery BEFORE the factory amp, and watch the speaker cone to see which way it moves. If the cone moves out, whichever lead is touching the + post on the battery is the + lead going to the speaker. If the cone moves in, then the + lead is the one on the negative post of the battery. Correct? DD And it would be OK to use my car battery, right (kidding)? Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted July 1, 2003 Share Posted July 1, 2003 Factory vehicle wiring color coding tables are available online, car audio installers reference them all the time for alarms, keyless entry systems, car starters etc. I am not sure of the specific website perhaps a Google search on vehicle wiring charts would yield something for you. Otherwise the method stated above will work fine. Quote Link to comment Share on other sites More sharing options...
formica Posted July 1, 2003 Share Posted July 1, 2003 ---------------- On 7/1/2003 1:56:20 PM dougdrake wrote: And it would be OK to use my car battery, right (kidding)? ---------------- lol... you joke about it... but there was someone on this forum that did just that after someone suggested a battery test but omitted the AAA part. I would have like to see their face when they connected those leads... Rob Quote Link to comment Share on other sites More sharing options...
BBB Posted July 1, 2003 Share Posted July 1, 2003 Now I get it! That's why Sears calls their battery a "Die Hard". See that. Ya learn somthin' every day.I bet they carry 12 volt party favors too.But can it core a apple? Ain't these variety stores entertaining? Quote Link to comment Share on other sites More sharing options...
prodj101 Posted July 1, 2003 Share Posted July 1, 2003 when my dad was a DJ in jamaica, he said his brother (not knowing anything about audio and just experimenting) plugged the 2 spekaer cables into a wall outlet. they said there was a huge pop sound followed by silence, lol. Quote Link to comment Share on other sites More sharing options...
ben. Posted July 1, 2003 Share Posted July 1, 2003 I've actually heard stories of people doing that in Europe, where their main outlets are 220V and banana plugs seem to fit nicely...... As to the battery test, the battery need not be before the amp, as it is sending a low voltage DC current that will simply hold the speaker cone stationary, either forward or backward. Think of it as half a square wave. Even with insensitive speakers I have never found this signal in need of amplification. Quote Link to comment Share on other sites More sharing options...
prodj101 Posted July 1, 2003 Share Posted July 1, 2003 just be careful when doing the battery technique, because this is DC, it is just the same as what happens when your amp clips severly, which is NOT good, lol. Quote Link to comment Share on other sites More sharing options...
ben. Posted July 1, 2003 Share Posted July 1, 2003 1.5VDC won't damage any speaker I've ever seen. It's a very low voltage for a speaker. Anybody have any numbers of nominal voltages for speaker levels? Quote Link to comment Share on other sites More sharing options...
dougdrake Posted July 1, 2003 Author Share Posted July 1, 2003 Thanks for all the feedback. I'll check on line to see if there is more info - I have a complete wiring diagram in the service manual I bought, but it does not indicate +/-. It just shows which wires go where. "As to the battery test, the battery need not be before the amp..." Actually, it does need to be before the amp because I am trying to identify which speaker-level lead from the head unit going INTO the amp is + for each of the 4 speaker sets. I'll be putting the high-pass filters into the line before the amp. I won't have the system powered on, so it won't be amplifying anything. Doug Quote Link to comment Share on other sites More sharing options...
lancestorm Posted July 2, 2003 Share Posted July 2, 2003 Doug, Tonite I randomally found this page that describes how to do it (as explained by a fellow Klipsch-ter above). Just adds some visual. I'm going to bookmark this one! http://www.techguys.ca/howto/speaker.html Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 3, 2003 Share Posted July 3, 2003 2.83 volts into an 8 ohm load is equal to 1 watt. Quote Link to comment Share on other sites More sharing options...
Professor.Ham.Slap Posted July 4, 2003 Share Posted July 4, 2003 ---------------- On 7/1/2003 5:21:49 PM bclarke421 wrote: Anybody have any numbers of nominal voltages for speaker levels? ---------------- We did a test on a car sub amp for physics back in the day. It was putting out about 82 VAC on average to two subs. It's higher than one might think. Quote Link to comment Share on other sites More sharing options...
reel 2 reel Posted July 4, 2003 Share Posted July 4, 2003 Is there still wire out there that is not marked...The side of the wire that is identified, is usually your common....ie....the positive side. Either with lines ...or printing or shape...anyway...............gc Quote Link to comment Share on other sites More sharing options...
TheEAR Posted July 4, 2003 Share Posted July 4, 2003 "when my dad was a DJ in jamaica, he said his brother (not knowing anything about audio and just experimenting) plugged the 2 spekaer cables into a wall outlet. they said there was a huge pop sound followed by silence, lol." Ya mon That woofa took a beating LOL They need to get better speakers capable of surviving AC tests. Quote Link to comment Share on other sites More sharing options...
Griffinator Posted July 4, 2003 Share Posted July 4, 2003 ---------------- On 7/1/2003 4:50:44 PM bclarke421 wrote: I've actually heard stories of people doing that in Europe, where their main outlets are 220V and banana plugs seem to fit nicely...... As to the battery test, the battery need not be before the amp, as it is sending a low voltage DC current that will simply hold the speaker cone stationary, either forward or backward. Think of it as half a square wave. Even with insensitive speakers I have never found this signal in need of amplification. ---------------- Actually, I know people who purchase service plans on their subwoofers and, when they get tired or want to upgrade, they do the old speaker-wire-into-wall-outlet trick. Blammo - new sub/credit towards better sub... Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 4, 2003 Share Posted July 4, 2003 don't speaker levels peak around 18v +/- ??? im pretty sure they go as high as 9v, but i could be mistaken... Quote Link to comment Share on other sites More sharing options...
Professor.Ham.Slap Posted July 4, 2003 Share Posted July 4, 2003 ---------------- On 7/4/2003 1:10:47 PM DrWho wrote: don't speaker levels peak around 18v +/- ??? im pretty sure they go as high as 9v, but i could be mistaken... ---------------- These were two rather large subs so that could be a reason. Quote Link to comment Share on other sites More sharing options...
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