May 06, 2021, 06:14:58 PM

Author Topic: Quickie DC pops and hiss  (Read 391 times)

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Offline bugeyes

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Quickie DC pops and hiss
« on: September 11, 2019, 03:11:43 AM »
Ever since I had built my Quickie, I've had random pops and hiss from the DC. I was wondering if I
could build an effective filter for this noise with a simple band pass filter. Any Ideas?

Offline Doc B.

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Re: Quickie DC pops and hiss
« Reply #1 on: September 11, 2019, 06:02:02 AM »
Sounds like a bad solder joint. Try reflowing your connections.
Dan "Doc B." Schmalle
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Offline bugeyes

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Re: Quickie DC pops and hiss
« Reply #2 on: September 13, 2019, 01:44:24 AM »
ok will give it a try, thanks..

Offline Jamier

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Re: Quickie DC pops and hiss
« Reply #3 on: September 13, 2019, 05:24:52 PM »
You should not have your Q too close to a Wi-Fi router. If you do, try moving them at least 15 feet or so apart. Also, if the problem persists, try adding weight to the 9 volt batteries. I place 4, 1 lb fishing weights on the 9 volts.

James Robbins

Offline Deke609

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Re: Quickie DC pops and hiss
« Reply #4 on: September 13, 2019, 06:51:12 PM »
You could also try this:

We have not experimented with extreme measures to kill unwanted RF interference, but here is an approach that might be effective:

1) put a small NPO ceramic cap, 27pF to 100pF, from tube grid (pin 3) to cathode (pin5). This shorts the RF energy so that it cannot appear between grid and cathode.

2) (optional) another small cap, around twice as large (56 to 220pF?) from pin5 to ground - this bypasses the cathode bypass cap to take that energy to ground.

Ceramic capacitors perform well at very high radio frequencies; and alternative is silver-mica caps. You want a physically small cap as well, so that it does not act as much of an antenna by itself.

Of course, replacing the chassis plate with a metal one, and fitting it into a metal box in place of the wood frame, and installing a tube shield, will shield all the circuitry, which may also help.

My son's Quickie was tuning in to various Asian language broadcasts - I did the double cap mod and it eliminated the problem. 

Roon Intel NUC ->  Yggdrasil DAC -> BeePre (w/ BeeQuiet and EML 300B)  -> Kaiju (w/ DCFil and EML 300B) or Stereomour II (2A3 [EML Mesh] and 45 Conversion [EML 45B])  -> Audeze LCD4