Quad hum.

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19-May-2017 02:58 PM

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Posts: 13

I have a Quad 33 pre-amp an FM3 tuner sitting atop a Quad 405-s power amp and I am getting a slight hum from both speakers. If I raise the Pre-amp up a bit (2 - 3 inches) it stops.  Is this normal.  I don't really want to raise the pre-amp, It just don't look so cool.

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19-May-2017 06:01 PM

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Posts: 10

For sure the hum is through the speakers?

The 405 tends to have hum from the trafo. Mine has it was well unfortunately.

Can also be something completely different. Perhaps the connecting cable between your pre-amp and 405 has a bad connection. Might just disappear when you lift it?


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20-May-2017 09:20 AM

Joost Plugge

Joost Plugge

Posts: 905

The 33 is very sensitive for outside magnatic fields, especially if you use the filters, don't place a 33 on top of anything electric!

Joost Plugge

DaDa Engineering

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20-May-2017 11:32 AM

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Posts: 13

Thank you Joost, I think you're right it's the standing the tuner and pre-amp on top of the 405-2 power amp that could be causing the hum. Pity they all look so good together.

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21-May-2017 12:20 PM

EJP

EJP

Posts: 1342

After about 50 years of considering and using separate stereo components I finally came to the conclusion that the pre-amp goes on top. In fact my main system, reading from the bottom, is:

Quad 306
Quad 306 (another one, these are biamped)
Quad CD67
Quad FM4
Quad 34
Quad 44 (because sometimes I need 2 tape inputs/outputs)

The reason is primarily convenience of access to the cables, but it also makes sense as the preamps deal with the smallest signals (phono) and so need to be furthest away from the power amps. (Tuners don't count in this assessment for reasons too compicated to express here.) There was also a heat reason but I have sadly forgotten the details.
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