Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Quickie => Topic started by: jake111 on April 25, 2014, 10:32:42 PM
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Hi all,
Finished my Quickie plus PJCCS and it makes my modded Trends amp really shine. The problem is it gets some volume controlled static plus hum if connected to my Airport Extreme. Also if not connected to the router, the closer it is the more of the same noise. Now if I play music I don't know that I can hear the noise. Still, if there's a cure I'm sure it could only sound better. Any ideas besides not using wifi? This is a wonderful hobby and especially Bottlehead.
Thanks, Jess
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Also, How quiet should it be without any input?
Thanks, Jess
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Last question first, to judge the internal noise of your Quickie you need to short the inputs and turn off everything else near it. You have already found that your Airport radiates noise that the Quickie picks up.
The reason for shorting the inputs is that tubes can amplify very high frequencies, they were originally used in radio and television circuits. Shorting the open inputs keeps the input from acting like an antenna.
Computers and cell phones are often the "perps" generating lots of noise that amplifiers can pick up. Additionally they can also have noise in the interconnecting USB or other cables.
If the noise is radiated then moving the offender away helps, as you have already found. If it is in the cable you need to isolate the receiving device. There was just one in Crack where going from USB to Toslink eliminated the noise.
Just some background information for you here. I don't stream music and don't have these problems. But I want to do it in the future so I am collecting data toward that end.
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The Quickie should be very quiet, at least mine is. There should be no AC hum, as it is battery powered. Very little hiss. There is ringing (microphonic), if you touch the tubes. As Grainger suggested, short the input and switch off other non-audio electronics.
Best
Michael
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Try grounding your airport extreme to earth. This can be a little challenging if the body is plastic, but doing so may solve your problem completely.
-PB
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Thanks for the advice peoples. I'll try some tonight. Not sure about grounding the router it seems to be a solid piece of plastic.Unless I can ground the negative part of the mini jack that plugs into it. Would that work?
I've never shorted anything intentionally. Could use some instruction on that one and do you short both jacks? I'm really new to this and could use some directions for the total novice.
I re-soldered all the ground wires and everything in line with them. Should I do the positive side to?
Thanks again, Jess
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You can earth the shell of an RCA jack and that should do the trick.
-PB
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Sound's good Paul.
I will try that after my latest issue if it is one.
This is: I turned off everything radio (phone-airplane mode, wifi, also apple tv), moved the quickie to the farthest room from the spaghetti monster which is my entertainment center. Now amp is battery powered too. So all is grid free. iPhone as source- off, mute, volume at zero, or unplugged. I'm getting a smooth static/rainy sound with my ear against the speaker. I guess it's much better now since it's balanced between the speakers and quieter. Is this normal?
Jess
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I'm getting a smooth static/rainy sound with my ear against the speaker. [...] Is this normal?
Yeah, that sounds about normal.
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Cool, Thanks so much.
Jess
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Hey,
With trying to ground the Extreme. Can I hack a piece of USB cable and use the ground wire from that cable? Since the USB jack is unused.
Jess
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It's worth a shot!
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K.
Which one is the ground wire?
Sorry I haven't a clue.
Jess
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(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fimage.pinout.net%2Fpinout_USB_files%2Fusb-pinout-diagram.gif&hash=98b8c9cb9041f3bf4e29093b3e77499248200bc7)
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You are great.
Jess
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There is also a 5th connection which is the metal casing of the USB plug/socket which is not the same thing as the - line. In some devices that shield isn't actually connected to anything at all and left floating, and on others its connected to the metal enclosure. I always found this rather puzzling and its different from device to device.
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I still would like to know about how to short the RCA jack.
I think I posted a pic. Would this short the RCA jack?
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Ok, you can build a shorting plug as Dan describes here:
http://bottlehead.com/smf/index.php/topic,586.0.html
Or go to Radio Shack and buy a pack of jumpers. They are wires with alligator clips on each end. Put one end of a jumper on the center pin of the RCA jack then the other end clips on the wire soldered to the outer conductor of the RCA jack.
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Thanks Grainger, just what I needed.
Jess
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Jumpers are just too handy not to have a bunch of them. I use them when trying out bypass caps. It allows me to add them and remove them until I make the decision if they need to be soldered in.
The shorting plugs come in handy any time I put in different output tubes in my Paramours. You need to adjust the hum balance pot with the input shorted.
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Yeah, the hum balance is what I've been trying to set. Turns out my meter was the problem. It wouldn't read that low.
Got a good one and hum is balanced. :)
Thanks, Jess
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The "hum balance" is a pot on Directly Heated Triode (DHT) amps that lowers hum caused by the AC heated cathodes. In a DHT the cathode itself is the heater. I have Paramours, they are monoblock versions of the Stereomour. To adjust the hum balance I need to short the inputs of the amps and adjust for the lowest voltage at the speaker outputs. It is necessary every time I swap tubes.
Don't get me wrong, I have only worn out one set of tubes but have several flavors of tubes I use.
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I've combined two issues/devices on this thread, sorry. Y'all still have been a lot of help. The hum balance was for a Stereomour.
Thanks, Jesse