nicks90 Posted July 21, 2009 Share Posted July 21, 2009 ok, so i hate hellektrikeries and i have got myself completely confused. I am still struggling with the upgrades to my speaker system in the defender... i have a nice headunit and have picked up via a friend of a friend some really good quality speakers and component mid/tweeters and all manner of fancy stuff. but as i now have 6 pairs of speakers to power and my headunit only has 4 channels - i need to get an amp really, cos i was told to not join 2 sets of speakers together and run them off one set of wires from the stereo. Plus i could do with more than 50w per channel to power the speakers, as they are all 150w RMS and 300W peak. 50w per channel from my stereo is a bit weedy for them "metallica moments" i occassionally have Looking on the bay-of-e i can pick up an amp no problems. Was thinking a nice mid range amp and run the 2 pairs of rear speakers from the amp and the front pair off the headunit. but i have a question about ohms. Most of the amps have specs for power output at 2ohms and 4ohms. But on the back of the 2 pairs of nice rear speakers i've got, it states the power outputs, but then says 6ohms. Can i use a 4ohm amp to fire up a 6ohm speaker or will the world blow up? cheers Nick Quote Link to comment Share on other sites More sharing options...
wozza35 Posted July 21, 2009 Share Posted July 21, 2009 Mine says 6 ohms on the subs and 4 ohms on the speakers and they are both powered from the headunit if thats any help Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 21, 2009 Share Posted July 21, 2009 Yes it will be fine, maximum power transfer won't happen, but that's only a small problem really. Quote Link to comment Share on other sites More sharing options...
crwoody Posted July 21, 2009 Share Posted July 21, 2009 .....Can i use a 4ohm amp to fire up a 6ohm speaker or will the world blow up?... Yes you can, there's no real problem with doing that except that you may not realize the full power of the amp. Whether you would really notice is another matter though. A higher impedance speaker will take less current from the amp and therefore deliver less power. Its a bit like comparing say, a 5 watt and 21 watt light bulb, they will both operate from 12 volts but the 21 watt one is brighter because the filament is a lower resistance so it draws more current. If you connect speakers of a lower impedance than that stated for the amp you are likely to damage the amp but going the other way isn't a problem. you could always double up on the output of an amp (carefully!) if an amp has a stated minimum load of 2 ohms you could safely connect two 4 ohm speakers to it in parallel. Clive Quote Link to comment Share on other sites More sharing options...
nicks90 Posted July 22, 2009 Author Share Posted July 22, 2009 cheers guys, suitable amp purchased! Just need to figure out some mountings for the 4 rear speakers and the wiring from the amp now. I've identified the 'soft start' amp wire from the headunit, so thats promising! Quote Link to comment Share on other sites More sharing options...
nicks90 Posted July 29, 2009 Author Share Posted July 29, 2009 oh for gods sake! why cant electrics be simple? having a stress with this bloomin amp. Just cannot get the friggin thing to work. +12v and ground wires from the amp directly to the battery, REM wire to the amp/antenna blue wire from the back of the stereo, RCA cables from rca out ports to rcs in ports plugged in, rear speakers wired in to relevant + and - terminals on the amp. Turn the stereo on and that fires up fine and the other 4 speakers still connected to the normal stereo speaker wires fire up as per normal. The amp powers up, well the green light comes on and the 2 rear speakers make a quiet "burdump" noise and then the green light goes out! Nothing, nadda, zip... light stays on for about 1 second before going out. turn the ignition off, stereo goes off like normal and then you get a simillar "burdump" from the back and the green light flashes on/off on the amp. hmmmmmm maybe the amp/antenna wire is faulty, so i wire the REM wire from the amp into a switched ignition live. Exactly the same thing happens. double checked the power cables, lovely and tight on the battery terminals with appropriate ring connectors, same at the amp. Checked the fuse in the fuse holder on the +12v cable, fine. Checked the fuse on the amp itself, fine. totally stumped. From what i have gleaned, when amps do this its cos its going into protection mode. but WHY? any help would be hugely appreciated. now i know why i drive a diesel. Can you imagine me trying to set up megasquirt on a V8 if i cant even get a flippin amp to work? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 29, 2009 Share Posted July 29, 2009 Protection mode will happen if there is a short in the speaker wires, the other alternative is you have a faulty amp... what make is it out of interest? Quote Link to comment Share on other sites More sharing options...
Aragorn Posted July 29, 2009 Share Posted July 29, 2009 Remove the remote line, and place a bridge between the +12v and REM on the amp and see what happens. Quote Link to comment Share on other sites More sharing options...
nicks90 Posted July 29, 2009 Author Share Posted July 29, 2009 its a caliber rally ca 2260 260w 2 channel amp. i'll put a bridge between the +12 and rem at lunchtime and see if that makes any difference. Also, one thing i forgot to mention in my tests - i disconnected the speakers in case it was them and hooked up a couple of 5" speakers that were originally in the back and it did exactly the same with those. So i'm pretty sure it aint the speakers or speaker wires. what about the wiring to the battery, could having a not thick enough gauge wire cause this? Dont know what wire it is to be honest - just looked nice and thick, poss 2mm thick multistrand. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted July 29, 2009 Share Posted July 29, 2009 My 300W RMS amp for my sub is wired up with 8guage wire. Its perhaps 4-5mm wide once you strip the insulation back. If it was too small it would just heat up and melt though. The reason i suggested bridging the REM connector is to see if the fault lies with the amp itself, or if the head unit isnt turning it on properly. Sometimes the blue "amp" lines on head units are actually for antennas, and the HU will only power them up when the radio is on. Quote Link to comment Share on other sites More sharing options...
DaveSIIA Posted July 29, 2009 Share Posted July 29, 2009 With the REM bridged to +12V, could you drive the amp with an iPod/MP3 player (3.5mm stereo jack to twin phono lead?)? This would prove the amp and speakers work ok. If it passes this test, then it is either the wiring to the head unit, or the head unit hasn't had the output enabled correctly. The Sony unit in my 110 has the option for sub out / line out / off. If set to sub out, the small speakers might not reproduce the low frequencies very well. Quote Link to comment Share on other sites More sharing options...
nicks90 Posted July 29, 2009 Author Share Posted July 29, 2009 just done a couple more tests on the amp, bridged the +12v and REM and it still does the same - when you touch the wire to bridge it, green light comes on for 1 second before going off, at the same time the speakers make a soft berdum noise. Take the wire off and the speakers make another berdum noise. So even though the green light has gone off, there must be something going on at the speakers, or they wouldnt make another noise when you take the power off the REM connector? yeah? no? not the foggyist. double checked what switches are on the amp, full or lowpass. its on full as the speakers its SUPPOSED to be driving arent bass subs. But it does the same thing on both settings. hmmmmmmmmmmm starting to think the amp is duff. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 29, 2009 Share Posted July 29, 2009 Disconnect everything except the power, and then bridge rem/+12V and if the light doesn't stay on you've almost definitely got a duffer. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted July 29, 2009 Share Posted July 29, 2009 Good call! Quote Link to comment Share on other sites More sharing options...
ThreeSheds Posted July 29, 2009 Share Posted July 29, 2009 now i know why i drive a diesel. Can you imagine me trying to set up megasquirt on a V8 if i cant even get a flippin amp to work? Ahh but if you were to drive a V8, then instead of fitting a mega-loud hi-fi to drown out the clatter, you could just listen to that lovely V8 burble... Quote Link to comment Share on other sites More sharing options...
dave88sw Posted July 29, 2009 Share Posted July 29, 2009 I don't know what you've tried already but it sounds like the trigger you're using from the headunit is in fact for an electric aerial and so is only powered for a short period when the radio switches on. Have you tried connecting the wire from the amp that should go to the headunit to a 12v permanent power wire just to check the amp works. If it were me i would start by JUST connecting the amp + and - wires direct to the battery and also the wire required to trigger the amp to check that the amp itself works, if it does nothing then send it back and ask for another Dave Quote Link to comment Share on other sites More sharing options...
nicks90 Posted July 30, 2009 Author Share Posted July 30, 2009 amp is fubar'd removed all cables (inc rca) except the +12v and ground and bridged the REM wire with the live - and again the light comes on for 1 second then nothing. Double checked all the voltages, getting the correct voltage on the live, and when the REM is bridged thats getting full volts too. So its a duffer. note to self - dont buy second hand amps from fleabay. just bought a new amp and should have it tomorrow and then Metallica can really let rip Quote Link to comment Share on other sites More sharing options...
nicks90 Posted August 3, 2009 Author Share Posted August 3, 2009 I GOT MY NEW AMP DELIVERED TODAY AND GOT ONE OF THE CHAV LADS FROM MY DESK TO HELP ME CONNECT IT UP AND GET ALL THE LEVELS AND STUFF SORTED. IT'S LOUD!!!!!!! SO SORRY FOR SHOUTING....I'M NOW TOTALLY DEAF got it all set so that at volume level 40 (max 50 on the stereo) - none of the speakers suffer any clipping or distortion from the amp powered speakers and component speakers driven off the headunit. JESUS it is incredibly loud and the clarity is superb! The bass speakers are right behind the centre bulkhead and after about 5 minutes of metallica - i swear to god my kidneys started to feel funny Top end is crystal clear and the mid range is just pure power. Both sliding side windows rattle like mad at high volume, so as a temp measure a bit of rizla packet has been jammed into the frames to stop that happening. Oh and as you drive along, the vibes through the truck make it feel like a prop is about to fall off! Mucho impressed. Had a 20 minute pink floyd moment on the way home at "fairly normal volumes" ( ) and i am dumbstruck. EVERY truck should have a good sound system. Nick (i'm not a chav really, i own no dance music) 90 Quote Link to comment Share on other sites More sharing options...
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