Quad 909 buzz problem

steevo · 14th May 2010, 07:40 PM

Just bought a Quad 909 from ebay 6 months old with 6 months waranty left on it. Excellent condition but one problem, a small amout of buzz coming from both speakers when plugged into my preamp. When not connected one channel does not have any buzz at all and is perfect the other has a very faint amout. when I connect each channel to the preamp individually, the bad channel with the very faint buzz increase in magnitude, the other channel has absolutley no buzz at all when connected on its own to the preamp. Connecting both channels causes a small amount of buzz to appear at their outputs. This is obviously destryoing the distortion and signal to noise ratio performance of amplifier and is annyoying me. I would expect more from quad. I Suspect there is an internal gronuding problem within the power amp or grounding system is wrong. Incidental there is no earth connection at the mian suupply. The mains supply is a standard kettle plug but the earth pin has been removed from the socket on the amp.

Anyone any ideas how to fix the buzz problem.

Cheers

peterhickman · 4th July 2011, 05:20 PM

Hi, this seems to be a bit of a common problem. Fidele Audio have a good fix but at the moment this is only avaialble with an upgrade. Quad have a fix but it seems there might be some sound quality degredation with there fix.

Tajzmaj · 5th July 2011, 12:15 AM

It looks like there is something wrong with your grounding system....?
606,707,909 and smaller 306,520...amplifiers has no center tap at the psu transformer but has floating ground which is fixed by help of 2 small transistors.....and because you remove ground from mains plug all other components connected to the 909 grounds them to this floating ground via 10E resistors on each board. My advice is to remove all the inputs and than observe this buzz. If there is nothing than amp is ok. If there is still some buzz than amp is defective....so send it back ......
Best, Taj

cdumper · 26th October 2011, 04:44 PM

after two unsuccessful attempts by Quad to cure my buzz problem and somehow them muting the musically of the amp to boot in their attempts i gave up bit the bullit surrendered nearly four years Quad extended warranty and sent my 909 to Fidele Audio. they fixed it, carried out upgrades for me and removed the Quadlink. Result .........absolutely superb. regards gw

14th May 2010, 07:40 PM	#1
steevo diyAudio Member Join Date: Sep 2005	Quad 909 buzz problem Just bought a Quad 909 from ebay 6 months old with 6 months waranty left on it. Excellent condition but one problem, a small amout of buzz coming from both speakers when plugged into my preamp. When not connected one channel does not have any buzz at all and is perfect the other has a very faint amout. when I connect each channel to the preamp individually, the bad channel with the very faint buzz increase in magnitude, the other channel has absolutley no buzz at all when connected on its own to the preamp. Connecting both channels causes a small amount of buzz to appear at their outputs. This is obviously destryoing the distortion and signal to noise ratio performance of amplifier and is annyoying me. I would expect more from quad. I Suspect there is an internal gronuding problem within the power amp or grounding system is wrong. Incidental there is no earth connection at the mian suupply. The mains supply is a standard kettle plug but the earth pin has been removed from the socket on the amp. Anyone any ideas how to fix the buzz problem. Cheers

4th July 2011, 05:20 PM	#2
peterhickman diyAudio Member Join Date: Jan 2009	909 buzzing Hi, this seems to be a bit of a common problem. Fidele Audio have a good fix but at the moment this is only avaialble with an upgrade. Quad have a fix but it seems there might be some sound quality degredation with there fix.

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5th July 2011, 12:15 AM	#3
Tajzmaj diyAudio Member Join Date: Mar 2011 Location: Ljubljana	It looks like there is something wrong with your grounding system....? 606,707,909 and smaller 306,520...amplifiers has no center tap at the psu transformer but has floating ground which is fixed by help of 2 small transistors.....and because you remove ground from mains plug all other components connected to the 909 grounds them to this floating ground via 10E resistors on each board. My advice is to remove all the inputs and than observe this buzz. If there is nothing than amp is ok. If there is still some buzz than amp is defective....so send it back ...... Best, Taj

26th October 2011, 04:44 PM	#4
cdumper diyAudio Member Join Date: Oct 2011	after two unsuccessful attempts by Quad to cure my buzz problem and somehow them muting the musically of the amp to boot in their attempts i gave up bit the bullit surrendered nearly four years Quad extended warranty and sent my 909 to Fidele Audio. they fixed it, carried out upgrades for me and removed the Quadlink. Result .........absolutely superb. regards gw

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