My Linkwitz Transform wants to violently rip my driver to bits - Page 2 - diyAudio
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Old 14th January 2007, 08:05 AM   #11
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Sorry Mike

Looks as if you posted while I was writing. And then I logged out. So I didn't get the part about the hum. It looks as if you either built a ground-loop or you are using insufficient mains filtering. Most probably the first of both.

Edit: Try to plug the LTF and the amp that is driving the sub into the same mains outlet as the rest of the system.

Regards

Charles
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Old 14th January 2007, 11:13 AM   #12
mikee55 is offline mikee55  United Kingdom
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Default Hi Charles

Hi, I've been trying wire the gnd up at various points. Seems like creating loops lessens the hum. Even connecting the chassis to the earth.My crossover is variable at 12db and fixed at 12db. Basicaly a 24db lowpass Linkwitz job. The variable section has a Linear pot wired to it, to allow me to tune it to my main speakers. The wires aren't screened. I figure if I moved it about, as its not mounted to the front panel, if it picked up anything it would change as it was handled. But nothing happens. I've added extra capacitance to the power rails, and that didn't help either.

As for ground loops, my wiring is of screened cable inputs and outputs.The tracks on the pcb's that carry the signal earths and automaticaly make up the 0volts rail for the power supply.The first board has a red, black and blue wire.Red and black carry plus minus volts and the blue connects to the gnd of the first board. Then the crossover and Linkwitz T. just use the Red and Black and don't have the blue. I've since wire extra earth wires here and there and only reduced hum by a small amount.

Everyone has said about Xmax and cone travel, well with this circuit,I'd say the cone doesn't travel that far and when I built the Circuit on Mr.Linkwitz's website(THOR), the cone didn't half move. Apparently its different to the Transform.

I can't wait to find out what it sounds like, when I've gotten rid of the hum.

Cheers Mike

(Where's richie000boy gone? Hope he's okay)
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Old 15th January 2007, 09:39 AM   #13
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Quote:
Then the crossover and Linkwitz T. just use the Red and Black and don't have the blue.
So I understand that they neither have signal- nor power- ground ?!

Regards

Charles
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Old 15th January 2007, 12:30 PM   #14
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I have only just seen this thread. It does sound like there is some confusion (maybe on my part) as to the wiring. Can you draw out how it's all connected?

Can you scope the output of the circuit to see if the hum is 100Hz or 50Hz?
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Old 15th January 2007, 12:49 PM   #15
mikee55 is offline mikee55  United Kingdom
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Default Its err...

...Dead.

I put its lid on, after craming a few things inside and somehow I fried the power supply, including the transformer!
So I can't do nothing till I buy some more op-amps at the end of the week.

Deeply mournful

Mike
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