help wanted by an ICE numpty

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macaroni
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help wanted by an ICE numpty

Post by macaroni » Thu Jul 05, 2007 1:32 pm

I'm really quite thick when it comes to ICE, so any help gratefully recieved.

I recently replaced the front speakers of my 480 with some JBL GTO527s, as recommended by a couple of people on this site.

The original speakers were working fine, but distorted at loud volumes and then I broke one whilst fixing a door.

I have connected the JBLs up OK, I think and secured them strongly to the door card and the door, but there are 2 problems:

1) the drivers side speaker is quieter than the passenger side
2) the passenger side speaker tends to crackle at high volumes. (possibly related to point 1).

Can anyone advise what I may have done wrong or suggest some diagnostics?

Cheers,

Antony

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kev
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NEW SPEAKERS

Post by kev » Thu Jul 05, 2007 1:45 pm

Hi, Is your head unit old?

Try one that you know is working fine.

Try swapping your speakers over to see if the problem
persists.

Check all your connections

Good luck

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robkendall
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Post by robkendall » Thu Jul 05, 2007 7:02 pm

point 1. your speakers are out of phase i think.....take one speaker and swap the wires around on the terminals....then see if its better.
basically one speaker pulls, one pushes if out of phase (iirc)

point 2. crackling/distortion....could be down to eing out of phase...not 100% sure.

silly as it sounds....asda sell a cd/dvd cleaner called discwasher....its a basic cleaner, but it has diagnostic tools on there too...it does sweep tests and phase tests and all sorts....only about 6quid iirc.

rgrds
rob
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t_w
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Post by t_w » Fri Jul 06, 2007 7:26 am

Isn't it just the 'balance' adjustment on the head unit? (or an other setting?)

Is the area (air volume) behind both speakers (approximately) the same?

About the phase of a speaker, it isn't very likely that one speaker would produce less sound when the polarity is changed.

This could give a rather bad sound staging or the music doesn't sound as it should be, (theoreticly one speakers damps the other so you can't hear anything at all, however, due to the reflections of the sound by the interior, this doesn't occur...) but it can't be the cause of your problem I think...


Grtz, Thijs

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robkendall
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Post by robkendall » Sat Jul 07, 2007 10:12 am

t_w wrote:About the phase of a speaker, it isn't very likely that one speaker would produce less sound when the polarity is changed.
im not by any means an ICE expert, but i was always lead to believe that this did in fact happen?

because basically, you have one speaker wire + to +, - to - as it should be,, and one wired + to - and - to +, so you get a flat out of phase sound....one speaker would be flat and powerless.
phase testing would see if it is the case.

please correct me if im wrong?
rgrds
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t_w
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Post by t_w » Sun Jul 08, 2007 10:49 am

It's not 'one' speaker which is out of phase, you'll always need two speakers. in other words:

Image
(sorry, some dutch language in the picture... just don't mind the legend for this one...)

Let the red signal be your left speaker and the blue speaker be your right. When you add the signals when your system is 'in phase', the output is higher then both inputs (black signal)

Now take a look at the right picture, both signals, blue and red, are out of phase now. The output (black signal) is much lower...

(as said, pure theoretical, disgarding the reflections...)

Sow it is unlikely that a phase problem is causing 'one speaker' to play less loud. The overall sound could be less, but you'll probably won't be able to point that down to 'one speaker'

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Post by JohnTurbo » Sun Jul 08, 2007 11:53 am

t_w is right.

I remember a demostration of this from my physics a-level involving a tank of water and two vibration generators.

I also studied it as part of my degree, but for some reason that part is a lot less clear in my mind.

Its known as wave interference.

There are some situations where one of a network of subs is deliberately reversed though....i think its for pressurising an enclosure posibly.
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robkendall
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Post by robkendall » Mon Jul 09, 2007 7:16 am

ok...that explains it much clearer, thanks guys.....!!

but im afraid it soesnt help the original question though :(
rgrds
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pol
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Post by pol » Mon Jul 09, 2007 7:30 am

I'd try swapping the speakers first.

It's also possible you have a dodgy bit of speaker wire grounding out to the chassis? I've had screws nick wires before which have caused problems.

How much louder is the the other speaker? Have you disconnected one of the built in door tweeters by accident?

Do you need a hearing aid?

pol

macaroni
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Post by macaroni » Mon Jul 09, 2007 10:14 am

Pardon? Hoho.

Thanks for all your replies. I think I may have solved the crackling problem. These speakers have rotating tweeters and I think I'd rotated it such that it touched the speaker cover.

I have tried swapping the wires round as I'm fully aware of the effect of phasing. The drivers speaker seems quite dull sounding compared to the passenger one and with the balance control centralised, I can hear the passenger speaker more than the drivers one.

Both the in-built tweeters are working correctly.

I will try and swap the speakers over and see what happens then.

Cheers,

Antony

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robkendall
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Post by robkendall » Mon Jul 09, 2007 10:17 am

JohnTurbo wrote:I also studied it as part of my degree, but for some reason that part is a lot less clear in my mind.
maybe something to do with copious amounts of liquid imbibed?
liquid of a more...shall we say....intoxicating nature?

;)
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pol
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Post by pol » Mon Jul 09, 2007 12:20 pm

Poppers?!

pol

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glasgowjim
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Post by glasgowjim » Mon Jul 09, 2007 1:06 pm

If when you swop the speakers over and the effect persists then get out the multi meter and check the voltage across both the speakers. Then see what the voltage is at each speaker when the balance is turned fully left and right. It may be that the balance point is not fully central for the speakers. (just a suggestion )

If its only one speaker thats problematic measure the impedance (resistance) of both speakers as one may be significantly different from the other.

Best of luck jim

macaroni
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Post by macaroni » Mon Aug 06, 2007 7:54 pm

To update this, I replaced the headunit and the problem seems to have gone.
I got a Pioneer DEH9200, I think, to replace my old Sony.

I guess the Sony was up to powering the standard Volvo set up, but not a set of JBLs.

I now want to wire up my amp and sub, but don't really know where to start with the big speaker.

I'll start another thread asking for help on that one!

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Post by michaelknight » Wed Aug 22, 2007 1:47 pm

if it makes you feel any better, i've had 2 stereos in my car and both times the passenger speaker volume is higher than the driver speaker anyway.

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