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Bottlehead Forum Welcome! Need support, you got it. Or share you ideas and experiences. |
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Bottlehead Forum Welcome! Need support, you got it. Or share you ideas and experiences. |
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In Reply to: RE: Some Help But Not Everything You Need To Know About FP III Noise ! posted by breakfastchef on October 6, 2009 at 16:44:42:
Let's see...I think the system can be silent. One of the tests is to short the hot to the ground (common) of each input at the RCA jacks and measure the hum (volts AC) at the output of each device. This gives you some measurement of what the component can do. In the case of the Paramounts, short the input and put your meter on the speaker leads. Then tweak the hum pot for the lowest reading. (I think that is in the manual, but if not here it is)
Second, if there is more hum in one channel swap the tubes from right to left. In the case of the Paramounts one tube at a time and adjust the hum pot when swapping the power output tube.
Third, the Paramounts should have a shorted input for this test. I have a cheap pair of RS RCA plugs with the hot and common shorted I use for this test. You say here that hum follows volume on the FP III. On the FP III for this test the input you are using should be shorted (what again?). If the FP III volume control still increases hum (and it could be the interconnects picking up some AC as they go between the components) you have very little to check. That means the hum is mostly before the volume control. Check the connections at the RCA jacks, the connections to the selector switch and the wiring between the selector switch and the volume controls. Again, maybe one channel is different than the other.
In the fourth example, there should be no interconnects between the two components. I probably forgot to say that. But the common wire of the interconnects grounds the two components together.
Fifth, good clue, there are boxes to isolate these two digital devices from the other animals. (Animal Farm reference here) And both devices can cause all kinds of noise in the system when running. Check with a search. Too many Bottleheads have banged their heads against a wall searching for noise that was caused by digital devices (not hum as I remember). Different wall outlets can be on a different incoming phase of the power. It is best to have all components on the same circuit breaker.
Sixth: Check the ground between the Seduction and FP III (is the chassis of the FP III firmly attached to the Seduction?). The Seduction will have more hum than other components as it has much higher gain for the tiny Phono signal. Test with the ground wire and turntable interconnects off and inputs shorted.
And finally, it is a standard practice in industry to use a + and a - signal plus a shield that is grounded at one end. You will have to have a connection to both hot and common coming through the interconnect. Plus a shield that is connected on one end.
Hope this helps.
Remember, YOU are the only one who needs to be happy with the sound of your system
Grainger Morrison
There Is Only One (Grainger Morrison, it seems)
Edits: 10/07/09 10/07/09
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- RE: Some Help But Not Everything You Need To Know About FP III Noise ! - Grainger49 05:27:28 10/07/09 (0)
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