Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Quickie => Topic started by: Loquah on October 23, 2013, 12:51:04 AM
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My Quickie has a hum that follows one of the tubes, but is also proximity sensitive. If I reach toward the volume control so my hand is near the interconnects and tube (I can't isolate to tell which of these induces the noise) there is a definite low hum on one channel. The affected channel follows one of the stock tubes.
Should I just clean the pins of that tube (they're a bit shabby) or would this be something I need to address under the chassis. It ONLY happens on the side with that particular tube no matter which interconnects I use, where the Quickie is physically sitting, etc.
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Cleaning the tube pins can never hurt, and might help. Look in my corner folder at the FAQ Thread (http://bottlehead.com/smf/index.php/topic,2408.0.html) for some suggestions.
Since the hum follows the tube I expect it is the tube. If it doesn't go away with cleaning try another one. If it persists, post back. It might be a ground loop problem in addition to the tube.
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Also had that proximity issue. Run a wire from the ground bus of the Q to your source. That solved it for me. There is a fairly recent thread in the forum too.
http://www.bottlehead.com/smf/index.php/topic,4794.0.html
Michael
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Thanks Zimmer, I missed that - I went looking only for thread titles mentioning hum
I'll clean the tubes first because my source is encased in anodized aluminum so no accessible earth. Could I use the ground on one of the inputs (e.g. Coaxial)?
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I guess it will work. My proximity hum even goes away if I touch the RCA ground on the Q myself.
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Did you clean the pins and swap in a new tube?
Touching the RCA jack signal common and losing the hum says it is an interaction with other component's grounds. It could be an interconnect with a ground that has broken loose.
Here is another thing to try. Unplug the input (selected) and put in shorting plugs. Unplug the other input cables at the Quickie. See if you have the same hum.
Here is Dan's post about shorting plugs:
http://www.bottlehead.com/smf/index.php/topic,586.0.html
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I guess it will work. My proximity hum even goes away if I touch the RCA ground on the Q myself.
This generally indicates the need to grab a scrap of wire and touch it between the chassis of the components you are using. At some point, you'll find the correct combination to null the hum.
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Thanks PB.
Is there any way to avoid having this extra wire? I'm trying to keep things from getting too messy.
I guess I could wind a secondary wire around an interconnect to the right device and will also look into a replacement tube, but is it possible to wire any extra grounding inside the Quickie itself to rectify this issue?
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Yeah, you can take power cord, cut the IEC end off, strip it back, trim off all the wires but the ground wire, solder the ground wire to the ground buss in the Quickie, then plug it in.
You could also open up the source with the floating output and add a wire from signal cold to the chassis earth.
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I received some new tubes for the Quickie today and was tickled to notice that they are Australian made (like me)!
(https://www.head-fi.org/content/type/61/id/965835/width/350/height/700/flags/LL)
I was able to get a matched set and am pleased to report that they have completely solved the hum I was getting with one of the supplied RCA tubes. The sound is now beautifully clean and bringing fatigue-free smoothness and warmth to my beloved S.E.X. + T1s combo