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Why not ground everything straight to chassis?
Why not ground everything straight to chassis?
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Old 11th October 2017, 04:53 PM   #11
scottjoplin is offline scottjoplin  Wales
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Quote:
Originally Posted by uzernaam View Post
Noise only happens when I plug an RCA into it (Whether or not that rca is connected to anything on the other end makes no difference.)
Does the noise change at all when you connect an input compared to no input? This is a power amp I presume, an unconnected interconnect will pick up noise. What happens if you short the inputs?
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Old 12th October 2017, 12:40 AM   #12
uzernaam is offline uzernaam  United States
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With shorted RCA inputs the amp is dead silent. Also silent when nothing connected.

Noise is clearly audible 10 feet away from the speakers when connected to a signal source, which for me is a miniDSP 2x4.

I'll take pictures as soon as I can. Right now I have to head to work...
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Old 12th October 2017, 01:37 AM   #13
Monte McGuire is offline Monte McGuire
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Why not ground everything straight to chassis?
Quote:
Originally Posted by uzernaam View Post
Since a solid piece of steel or aluminum is essentially a very large gauge wire with near-zero resistance, why not come directly out from speaker ground terminals, rca shield terminals, amplifier grounds, the ground wire from the AC plug, and everything else with a less than 1-inch wire and bolt it straight into the chassis?
I used to own a commercial recording console, a Neotek Series II, that did basically that. The frame was made of thick aluminum extrusions, and everything was grounded to the frame as many times as possible. The entire circuit was unbalanced, except for the mike amp inputs, and the noise was extremely low. The console did use an external AC power supply, which IIRC obeyed normal grounding rules separating the chassis and audio ground, but the chassis of the console itself, all 6' by 4' of it, was grounded aluminum extrusions.
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Old 12th October 2017, 09:54 AM   #14
DF96 is offline DF96  England
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Quote:
Originally Posted by kaputt
I was just wondering about common practice of wiring in the heyday of tube technology. There's not much difference between NF gear (e.g. a Wurlitzer Sideman) oder HF gear (e.g. Tektronix 511) as there's a bundle of wires bundled together with a lineman's knot, not much twisting of wires anywhere, no star grounds...
50 years ago it was expected/accepted that valve audio equipment would have some hum.

I assume that Tektronix know how to design grounding, rather than follow recipes.

Last edited by DF96; 12th October 2017 at 09:56 AM. Reason: make it clear who I was answering
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Old 12th October 2017, 05:05 PM   #15
scottjoplin is offline scottjoplin  Wales
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Quote:
Originally Posted by uzernaam View Post
With shorted RCA inputs the amp is dead silent. Also silent when nothing connected.
Noise is clearly audible 10 feet away from the speakers when connected to a signal source, which for me is a miniDSP 2x4.
A ground loop via the interconnects then, could be a cross channel loop via the DSP, unlikely though. Is the DSP earthed?
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Old 12th October 2017, 05:15 PM   #16
uzernaam is offline uzernaam  United States
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The miniDSP connects to a PC via USB cable. It gets power from a 2-prong power adapter. If there is a ground on it, it comes from the USB.
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Old 12th October 2017, 05:36 PM   #17
scottjoplin is offline scottjoplin  Wales
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People often complain of hum when connecting to a PC.
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Old 12th October 2017, 06:01 PM   #18
geezertron is offline geezertron  United States
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Quote:
Originally Posted by uzernaam View Post

2) Use a different transformer - one with a screen and/or flux band. Mine is already installed, I'm not going to use a different one. I'm not sure how to add a flux band to a toroidal transformer, or if it is even possible. I don't know if this comes with a screen.
Do not attempt to put anything like a flux band around a toroid. If it makes any connection that goes around the outside and through the hole (i.e. same as the windings) it will act like a winding with 1 turn and get very hot, very fast.
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Old 12th October 2017, 06:06 PM   #19
cbdb is offline cbdb  Canada
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Quote:
Originally Posted by uzernaam View Post
The miniDSP connects to a PC via USB cable. It gets power from a 2-prong power adapter. If there is a ground on it, it comes from the USB.
Can you try a different source?
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Old 12th October 2017, 07:14 PM   #20
DF96 is offline DF96  England
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What "noise" is the OP hearing? He hasn't yet told us. Hum? Buzz? Whistles? Crackles? White noise? Are we investigating a PSU problem or an input stage with parasitic oscillation?
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