 | Home > In Car Electronics > 90 Hard top rear speakers |
 
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| rossy Member Since: 29 Nov 2010 Location: Co. Roscommon Posts: 1296   
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thanks re polarity. I have a multimeter somewhere and hopefully the instructions too !
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10th Dec 2012 8:50pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20376 
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 $W33T $0U7H3RN $UG4R
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10th Dec 2012 8:52pm |
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| mike.29 Member Since: 14 May 2012 Location: Scotland Posts: 22  
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Any idea where this plug would be? Is it behind the dash board or in beside the engine? I've just had the CD Player out and there is no wires connected to the ISO plug on the back. Also there is no voltage across either of them no matter what I do (Brake lights side lights ect) Thanks again Michael Michael 08 2.4 TDCI Defender 90 61 2.25 Petrol 88" Series 2 53 2.00 Petrol 80" Series 1 |
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17th Dec 2012 3:33pm |
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| db950 Member Since: 01 Feb 2012 Location: Lincoln Posts: 560 
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Hi Michael, the plug should be on/near a bracket near the clutch pedal box under the bonnet.
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17th Dec 2012 7:31pm |
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| 1113562 Member Since: 17 Nov 2013 Location: Abergavenny, Wales Posts: 6  
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My goodness there is a lot of confusion in this thread. Do the wires exist or not, what is the colour coding, how much copper do they have to support high power etc etc. One thing is for sure it doesn't matter which polarity you wire speakers, it will not damage them, they will just be out of phase if you get them inverted compared to others in the system. The out of phase will tend to cancel bass frequencies that is all so just reverse them and see if bass improves if you cannot buzz the cables back to the source. I'm going to try and fit some to my 90 TDCI so I will find out what is what.
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17th Nov 2013 10:17am |
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| 1113562 Member Since: 17 Nov 2013 Location: Abergavenny, Wales Posts: 6
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Having now fitted rear speakers to my 90 hardtop I can confirm that cables do exist between the rear light clusters on both sides and a plug mounted on a bracket close to the clutch pedal hydraulic master cylinder. Rather odd that this plug is located in the engine bay and not routed onward to the back of the radio behind the dash. Anyway I measured the loop resistance of the fixed wiring from the plug to the LH rear speaker spade connectors by putting a shorting loop at one end and measuring from the other end. I measured 0.65 Ohms. Not bad seeing it goes quite a way. The RH loop resistance was a little less at 0.6 Ohms. This resistance will create some losses but for normal 30 to 40 Watt RMS speakers with an impedance of 4 Ohms like it does not represent a significant power loss. About 16%. So if you want to improve on this power transfer efficiency you would need to run in cables with more copper cross sectional area to get the resistance down. Anyway I decided to use these cables to connect my new speakers, a pair of JBL 2528S's (which are actually lower impedance than 4 Ohms so cable loss will be more significant however...). As I had already panelled out the top sides (from the door pillars to the back side windows) with 9mm plywood I wanted to mount my speakers into these panels rather than the normal pods behind the lights. The panels provide a more substantial baffle and a bigger bass cavity. I used a wad of bubble wrap stuffed between the plywood and the aluminium side panels to stop any resonance which worked a treat. Anyway this change of position meant I had to extend the connections about 500 mm upwards and drill a hole to get the wiring up into that space. I used crimp spade connectors and normal pair speaker wire for this modification. The next and most significant issue was extending the wiring from the plug near the clutch pedal to the radio. The plug is some automotive square plastic thing with 4 thin spade terminal inside. As I did not have a mating socket for this plug I cut it off and fitted more in-line crimp spade terminals. I then extended the wiring from this position to the back or the radio using standard pair speaker wire. Routing these wires through the bulkhead and across to the radio was a bit of a nightmare but there is a convenient rubber cable entry panel directly above the clutch pedal box with two spare ways. I had to remove a small dash panel beneath the steering wheel to help pull the wiring through using a 1.6 mm tig welding filler rod to poke a route through then soldered a copper stranded wire to the copper coating of the filler rod and pulled that through. I then had a decent wire to pull through the two pairs of speaker connection wires. Routing the wires from to the back of the radio from the access hole under the steering column and to the left was a lot easier, with the radio removed of course. After all this effort I was finally able to connect my Kenwood DAB/MP3/USB radio and JBL rear speakers and WOW the sound is amazing. Previously I had fitted Tweeters to the front speakers in the two positions on top of the dash next to the windscreen pillars. For some reason my model was not fitted with these tweeters, perhaps these are a county pack upgrade? Anyway with the tweeters and the 6.5" JBLs at the back the sound is amazing...a worthwhile upgrade I would say.
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17th Nov 2013 9:35pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20376
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Glad it's going well.
Having read through this thread again I see the polarity issue as being a bit silly. Yes, the polarity won't cause damage but why reverse it and put it out of phase and not care about it when best practice is to use the correct polarity in the first place?..... (And match the rest of the system) If people found LR's speakers polarity opposite from the factory people would play up merry hell about it just for it simply being wrong. Of course with out stating the obvious you will have to have the HU powered and playing to detect voltage present in the positive feed. If it is off you will get no power through any of the wires you test. You can of course test that the earth is present. (One of those why did I not do that moments that you might not even realise or think of) No one on here professes to be an expert but just give friendly advice, people's views differ in some instances but best practice is best followed for a multitude of reasons and especially for safety. Finally we that do offer a bit of advice such as myself or Barbel Jim or any other contributing user only do so because we choose to from our free time for the benefit of others and the site. Just through goodwill really, we / I are not even site sponsors nor making money out of it at all but simply lending a helping hand or a little help for those that ask it. $W33T $0U7H3RN $UG4R 🇬🇧🏴🏴🏴🇮🇪🇺🇸⛽️🛢️⚙️🧰💪 |
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17th Nov 2013 11:39pm |
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| 1113562 Member Since: 17 Nov 2013 Location: Abergavenny, Wales Posts: 6
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Of course you want all the speakers to be in phase for the best sound that goes without saying but its not going to kill you or do any damage to your equipment. In addition NOT all HU sources (Radio's CD' etc) and particularly separate amplifier units employ class A amplification so it is a bad assumption to suggest that the wire with the signal on it is always positive relative to earth. To get higher power full push-pull differential drive is employed in these devices meaning the negative lead has the same signal but 180 degrees out of phase. The best way is to buzz the wiring right back to the source. If you are using different speakers (i.e. different model front to back or from different suppliers) it also cannot be assumed that they use the same convention for their terminal notation, i.e. the cone may move in the opposite direction for the same applied polarity signal so the best way to find this out is to apply a small DC voltage to both types and see which way the cone moves. Note you only need a few volts to do this like a 1.5V battery for instance and this will ensure no damage is inflicted. Indeed even 12V would be OK unless its a puny speaker but it will make a hell of a thump.
PS. In this instance its nothing to do with best practice it is to do with connect it up right and it will sound better. Don't confuse this with H & S issues. There are a whole lot of so called 'professionals' out there who will play the H & S card when it is absolutely unnecessary. Shoot me if I'm slowing you down! |
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18th Nov 2013 7:07am |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20376
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It's just the fact that they are designed to be powered with the polarity as marked on them. Was not trying to have a pop at anyone just saying how I do things. As I mention if others do another method that is their choice with their Defender.
$W33T $0U7H3RN $UG4R
🇬🇧🏴🏴🏴🇮🇪🇺🇸⛽️🛢️⚙️🧰💪 |
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18th Nov 2013 12:14pm |
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| 1113562 Member Since: 17 Nov 2013 Location: Abergavenny, Wales Posts: 6
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How does a speaker know it is wired the wrong way around? How can it be "designed" to work one way and not the other. Its just a coil hovering in a magnetic field that is connected mechanically to the cone. It is a completely balanced transducer so reversing a speaker has no affect whatsoever providing all of the other speakers are also wired in reverse and even then it will only affect low frequency bass and lower mid range which will tend to cancel acoustically. At higher frequencies the wavelengths are short and coherence between speakers can only be found at specific points in space and then only in a narrow frequency band. Outside of that frequency band coherence moves to a different point in space. This is why higher frequencies are directional and why non directional deep bass signals only need one Sub Woofer speaker. Shoot me if I'm slowing you down!
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18th Nov 2013 11:21pm |
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| aldof Member Since: 16 Jul 2015 Location: Rome Posts: 10  
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Hi, may I ask where you got the 6x9 "pods from? Going bananas to find them on the net... Thanks!!! Aldo (Rome, Italy) 110 Td5 MY05 Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated  |
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20th Oct 2015 12:13pm |
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| V8Simon Member Since: 17 May 2016 Location: Prestatyn, Wales Posts: 147 
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I think this is the connection for the rear speakers from the loom.
 Click image to enlarge Click image to enlarge Click image to enlarge |
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18th May 2018 3:57pm |
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