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      10-14-2008, 04:23 AM   #1
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amp interference

just had the amp installed (blaupunkt tha555) and I'm getting interference (as in a whine from the speakers that rises with revs). Anyone got any ideas, at huets at the moment and they can't figure it out
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      10-14-2008, 04:57 AM   #2
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Hmmm,

did they run the cable down the left hand side of the car and not down the right hand side where all the power cables are??

If they are installers I doubt they did but you never know?!

Also, did they ground the negative to the battery??
So power cables straight on the battery positive and negative??
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      10-14-2008, 05:18 AM   #3
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they've run the cables down the right! Theysaid they tried the battery direct but it made it worse
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      10-14-2008, 05:20 AM   #4
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asked them to move the cables down the left, they're moving them now. Taken 6 hours so far and counting
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      10-14-2008, 05:24 AM   #5
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6 hours!!??
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      10-14-2008, 05:25 AM   #6
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Hold on, they haven't connected the power and gorund on the back of the harness at the stereo end and then hooked directly to the battery??
That would leave and open loop and bring in interferance.
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      10-14-2008, 05:37 AM   #7
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not sure, surely they're not that thick?
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      10-14-2008, 05:45 AM   #8
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right. Just tested it with it down the left and guess what, no inteference! Still a tiny bit of system hiss though.
7 hours and counting.
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      10-14-2008, 05:48 AM   #9
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You also need to make sure the gain is set at its lowest, this is still slightly too high, but will reduce hiss.
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      10-14-2008, 05:49 AM   #10
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also they've got the power going through the head unit because it was giving more interference, asked them to try it with the battery
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      10-14-2008, 07:43 AM   #11
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OK just got back. 300 quid in total, ouch.

Ran the power through the head unit as going through the battery caused real interference again. Im beginning to think there might be a problem with the amp itself. Even so, sounds great and a real improvement (maybe not nearly 700 quids worth though). I think the levels need tweaking, Im getting bad crackling at high levels from the tweaters and components (or maybe thats just me playing it too loud?).

Gizze, is there a good group of settings for this amp? (what about the seperate bass controller, have that up or down?)
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      10-14-2008, 07:49 AM   #12
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Unplug that as well, that causes more interferance than anything.

You want the gains on as low as they will go, and then the sub channel set so you can just hear the subs come in, because you have removed the sub control you will find it is about 6v needed, that is of course when all settings on the head unit are at 0.

I then set the fader to +7 towards the front.

These are input sensitivity pots on the amp, not volume, you are trying to match the head units voltage, in this case it is 9v, so you want to set them to 8v, otherwise you may damage the amp or head unit. You installer should know this as it is the absolute basics of car audio, so if they are on anything other than 8v I would be a little disappointed.

I can not believe you paid £300 for this install, who the hell did it??
They have charged you for their incompetence basically.
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      10-14-2008, 07:50 AM   #13
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Have you got the SWS subs in???

There is not enough current to drive the subs off the head units power, you must run cables to the battery for this.
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      10-14-2008, 08:02 AM   #14
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Yep, all installed. Asked him about it, he says the head unit isn't driving anything (as in, its not drawing power itself, more like through it) so wont effect the power getting to the speakers. Sounds like bollocks to be honest.

Here's the current settings:
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Last edited by trixman; 10-14-2008 at 08:19 AM..
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      10-14-2008, 08:21 AM   #15
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Of course it is not drawing the power through the head unit, but the head unit is sat on a circuit that can only draw so much current.

The Amp running just speakers can also use this same 12v feed, however if you have added subs you need to take a direct 12v feed from the battery.

It is worth doing this anyway as running the power cable down the side of modern cars with can bus can cause interferance as the power cable picks up nopise from the data network.

The battery in the boot of a BMW makes it a dead simple task.




Now, looking at your settings theyt are incorrect.

You need to set the front and rear levels to 8v, and do that NOW!
Turn is as far as it will go anticlockwise.


You also want to set the pass on the front channels up properly, unplug the sub speakers from the amp, now play something with bass, set it to 200hz or whatever it goes up to (clockwise) and slowly move it back towards 20hz. Keep going until you do not hear it going any deeper, will be about 100hz (approx).
Fine tune till you are sure it is as deep as it will go, you want as much bass from the fronts as possible, but you also want to stop bass you can't hear from reaching the drivers so you can push them with no distortion.

Now you want to set the subs up so they match what you have on teh fronts, so if you got down to 100hz on the front speakers set the subs to do everything below 100hz.

Now when this is done you fine tune the sub gains, the drivers are not as sensitive so you will have this above 8v, probably around 6v, it may take a few days of tweaking to get it so you can hear them but don't know they are there. If that makes sense?

Then use your bass and treble to fine tune.




With the rear channels I actually use the low pass filter, so I cut out the treble so it gives some rear fill but doesn't drag the soundstage into the rear, vocals stay up on the dash. So I set it to cut out everything above 5000hz I think it is, and then use the high pass so no bass below 100hz gets through either, so they are only there to add some fill in the rear.



With this set up you should be able to drive the speakers very loud, no distortion at all and without risking damage to your head unit or amp.
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      10-14-2008, 08:27 AM   #16
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Cheers Gizze, your a lifesaver/walletsaver

The green power light seems to stay on also, which Im guessing means the amp is permanently on. Haven't checked whether it stays on for a certain amount of time though, but if it does I'll have to get that sorted
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      10-14-2008, 08:43 AM   #17
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Bloody hell Paul - im glad thats one mod i didnt bother doing to the car, seems like a real headache!! Gizze has been an absolute star for you matey, you owe him a big drink!!
Ps; any chance of getting those plates back to me asap???
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      10-14-2008, 08:46 AM   #18
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Yea sorry mate, they're in the car just haven't had time today (as you can see!). Really thought giving it to a company would have been easier, to be honest following gizze's original plans myself would have been the best plan.
I'll drop the plates down to post office tomorrow for you.
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      10-14-2008, 09:05 AM   #19
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Thanks buddy. Let me know when you want to come and collect the exhaust.
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      10-14-2008, 02:48 PM   #20
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mines been in a while now and still whines a bit - cables are down the centre of the car which I suspect might be the problem

It's a fiddly job to fit but not £300 worth
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      10-14-2008, 03:03 PM   #21
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My power cable is run down the left and no signs of interference from mine.

Really good info from Gizze again think he will start charging us soon

I think the green light stays on for 10-15 minutes after the ignition is switched off.

Hope you get it sorted to your satisfaction Paul
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      10-14-2008, 04:30 PM   #22
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Quote:
Originally Posted by MOB View Post
mines been in a while now and still whines a bit - cables are down the centre of the car which I suspect might be the problem

It's a fiddly job to fit but not £300 worth
Yea they run mine down the centre too, still doesn't explain the extra interference if it hooks up to the battery (which it should).

On the plus side, took the front gains down as a stopgap until I get to fiddle properly and it stopped the hiss.... thanks again gizze!

Cheers Gary Im sure it will work out fine, unless the amp is knackered, which will be a tough one to work out.
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