little BASS on the left rear output

[khalil]

can someone help me on this please, i put a alpine amp and a sub in the boot, tapped the the signal from the headunit from the both rear outputs, theres lots of bass, but much much more from the RIGHT output, i noticed this when i put the balance to the left the sub does pump that much,but much much more when i fade it to the right, obviously when i put it in the centre it does sound ok, so can someone tell me way the bass is not equal on both right and left balance, car is a audi a3 2004, with BOSE / concert II, the single cd player one,
cheers all

 

[AndyMac]

Where and how did you tap the signal? If you tapped the line level output at the Bose amp then you should have equal amounts of bass left or right. If you used the feed to the Bose sub then this will give you right rear and left front signals. So if you fade to front left you will find the missing bass. Bose do this so that if you fade to front on the stock system then you still get some sub woofer and vice versa.
If you have tapped the signal at the Bose amp along with the remote on trigger then it's likely just a bad connection, so you need to check the piggybacks and ensure they are well taped up or zip tied so that they can't move around.

 

[khalil]

i was hoping that you would answer this for me mate, cause your know your stuff,

ok what i have done is cut the RCA's, i wass left with two wires coming out of each rca, one was in the centre with the covering on the other wraped around the wire which looks like copper, you know the sort when you cut a rca,

anyway the left rca(centre wire) was tapped to pin 1 (line out RL) (connecter 1) and the other copper wire from the same rca was tapped to pin 3(line out GND) (connecter 1),

the right rca was tapped to pin 2 (line out RR)(connecter 1) and the other copper wire from the same rca was tapped to pin 3 (connecter 1)

so the problem now is if i use the balance , when i put it all the way to right theres lots of bass, but when all the way to left theres little bass, way isnt it level?
please help mate, or is the rca me using might have a split or maybe a bad channel in the amp (hope not)

 

[AndyMac]

Well that's spot on in terms of the wiring. Where have you made the connections?
Also stupid question but the Alpine amp input mode is set to ch1+ch2? If you set it to Mono then you'll only get input from ch1 IIRC.

 

[khalil]

i have made the connection at the headunit, ye the alpine does hane ch1+ch2 or ch1 mode, it make no differnce if i switch inbetween the two modes apart from if its in ch1 mode i get alot more bass, but the balance problem is still there, me little stuck with this one as i cant figure why its doing that,what are the possiblitys?

 

[AndyMac]

Well it can only be a poor connection.
Just to rule out the Alpine, have you swapped the left & right to ensure both channels are working on the Alpine i.e. swapping them over should give you the opposite result if the amp is OK.
How have you managed to tap the loom at the HU and keep the connector in place to feed the Bose amp? I use piggybacks on the Bose loom at the amp in the boot and if the connetion isn't 100% then get the same weak signal on one of the channels. Using piggybacks at the HU will be difficult as there's so much movement on the wiring when you pull the HU in and out, it would be tricky to get a 100% reliable connect.

 

[khalil]

what i have done is used one of those wire clamps, the sort that you put the 2 wires you want to connect and it has a sort of a metal plate in it, when u use a piler and press them they connect,

 

[khalil]

is possible that the left channel on the amp is blown?

 

[khalil]

Well it can only be a poor connection.
Just to rule out the Alpine, have you swapped the left & right to ensure both channels are working on the Alpine i.e. swapping them over should give you the opposite result if the amp is OK.


this is the wired bit when i swapped the left & right instead of giving me oppsite results, it gave me the same results, also what i noticed is if ii pull off the left rca from the amp and have just the right rca in, and if i fade it to the left (you would think there should be no bass) but the funny thing is there is bass

 

[AndyMac]

Yes those are piggybacks, and are very unreliable, however if it's giving you the same result when you swap channels then it's the amp that's faulty. It gives you bass from a single channel because the amp is in ch1+ch2, so pairing the 2 channels at the input stage. Switch the amp to stereo and it probably won't play when you pull the left RCA. It's most likely the output stage is blown, however I presume you're running it bridged across 2 channels, so the output stage on both channels must be OK otherwise you'd get nothing. Which Alpine is it and how is it wired? i.e. bridged into single sub, 2 channel into 2 x 2ohm voice coil etc....
If you have some spare speakers try it running those in stereo and see what you get from the duff channel.

 

[khalil]

Yes those are piggybacks, and are very unreliable, however if it's giving you the same result when you swap channels then it's the amp that's faulty. It gives you bass from a single channel because the amp is in ch1+ch2, so pairing the 2 channels at the input stage. Switch the amp to stereo and it probably won't play when you pull the left RCA. It's most likely the output stage is blown, however I presume you're running it bridged across 2 channels, so the output stage on both channels must be OK otherwise you'd get nothing. Which Alpine is it and how is it wired? i.e. bridged into single sub, 2 channel into 2 x 2ohm voice coil etc....
If you have some spare speakers try it running those in stereo and see what you get from the duff channel.

the amp is a alpine mrd-m1001 mono amp, and the sub is a single voice coil 4 ohm sub

 

[khalil]

think my first step should be that i get the wires connected more better, think me going to solider them to get a better connection,

if problem is still there can a audio shop check some how with some equipment if a channel is blowm/faulty?if its that channel blown is it repairable?

 

[khalil]

thanks mate got it all working, you was right it was a bad connection, solidered all the wires, and it works perfect, thanks so so much for your help,i wouldnt have thought it was a bad connection, thanks matey