Some Odd Quickie Noise

[polyghan]

I built my Quickie maybe a week or two ago. It measured fine so I plugged it into my setup and it sounded great! I then listened for a couple hours. The next day, I turned it on and was going to put some music on only to find that it was making some strange noises. The first was a pretty quiet buzz (ear next to tweeter to hear it, not a big deal) and the other was a very strange sound, an intermittent fizzling or sizzling sound. The best way I can describe it is like a higher pitch version of the sound you get when drinking the last bits of soda through a straw in one of those disposable fountain drink cups (or similar to the sound you get when you sip a liquid from a glass). It's extremely intermittent in both when it occurs and how loud it is. When I just turn it on, it never makes the sound, but maybe 30 seconds after it starts up a little, then goes away, then comes back, then goes to the other channel, then goes away, etc at random. It can stop for 10 minutes then come back, or stay on for the whole time. Volume ranges from inaudible at listening position (have to have the ear at the tweeter to hear it) to very noticeable at listening position. I do not have to have music playing for the sound to occur, and volume level does not affect it. If I remove the Quickie from my setup the problem does not occur.

I have already resoldered/melted all of my solder joints and while it may be a bit more infrequent now, I can't say for sure (since it was working great until a day after I built it and I just recently remelted the solder points) and it is still certainly an issue.

I did recently switch the tubes and I may be noticing more of the sound coming from the right channel as opposed to the left channel before, but I can't be sure of that since it occurs on both channels.

Currently I am using an Emotiva XDA-2 digital pre as my preamp and DAC, this connects to the Quickie which is set at 3 O'clock on the volume knob (volume control is handled by the XDA-2 because it has a remote) and the Quickie outputs go to an Emotiva XPA-200. Using this setup without the quickie is noise-free.

Thank you to anyone who can help!

[Paul Joppa]

First guess is you have a cell phone in your pocket.

Second guess is a bad tube or a bad solder joint or a bad tube socket connection.

[polyghan]

I do have a cellphone in my pocket. How far does it have to be from the amp to prevent any issues?

How would I check for a poor tube socket connection or a bad tube? Would a bad socket connection or tube on one side affect both channels? I did just resolder, but I certainly wouldn't say it's out of the question that I made a mistake.

[polyghan]

I stuck my cellphone right next to one of the tubes and fiddled with it. I did hear noise, but it's different from the noise I am experiencing (it was more of a tick tick tick rather than a fizz).

[polyghan]

I recorded the sound and uploaded it to give you guys a better idea of the noise. The recording isn't perfect, the normal noise is smoother than in the recording (it was recorded with a cellphone). Apologies for any extra noise.

You can listen to it here:
https://dl.dropboxusercontent.com/u/41961113/tubeampissue.wav

Also, I tried swapping the both tubes between the two channels to see if it was one specific tube and I don't think that's the case. It does seem to be pretty random which channel makes the sound when.

[Doc B.]

If this was an AC powered amp I would have guessed that was a bad filter capacitor. It's a very unusual noise to hear from a Quickie. The most likely possibility is still a bad solder joint, that didn't get fixed by the last touch-up. Have you tried different batteries?

[polyghan]

I'll do another reflow when I have the time (I'll try to get it done today), is there any specific part of the circuit I should be focusing on?

I have tried different 9 volt batteries since I had some lying around, but haven't tried new D-cells. I can grab some D-cells if you think it may help.

Is it possible that it's a tube issue?

[Doc B.]

Yeah it could be a tube issue. The fact that you hear it in both channels makes it hard to be sure, as usually a bad tube will just make noise in the channel it's plugged into.

[polyghan]

Got some new batteries and put them in, all batteries are now a different brand and new. Issue still pops up. I'll reflow tonight.

[polyghan]

Did another reflow, no dice, still the same issue. I don't believe it has gotten better or worse.

EDIT: Also, the noise sometimes also coincides with a very quiet "bong bong" from the tubes (even if they aren't being moved), but I can't say whether they are related, the "bong bong" is rarer than the fizz.

[Doc B.]

I could suggest wiggling the wiring a bit while the system is running, but there is a risk of popping speakers or setting off the amp's protection circuit and I don't want to talk you into harming your system. If it was here in the lab we would probably hook it up to a low powered amp and a cheap speaker and poke around a bit to see if we could narrow down the source. Short of that I guess the next step would be to try some other tubes. You can contact Josh at replacementparts at bottlehead dot com and request a replacement pair. 

[polyghan]

Just poked at all the wires with the wooden end of a small paintbrush (also the resistors and caps). Only one wire caused it to make any noise other than standard microphonic sounds, but it was only one time. Subsequent pokes did nothing to the same wire, so I would chalk that up to coincidence.

Also, see edit above, I posted the edit right as you posted, not sure if it means anything or is abnormal.

Thanks, I'll contact Josh and update as soon as I try the replacement pair.

[charger]

is it possible to put a snubber  in the Q to cut out phones noises?

[Paul Birkeland]

Yes, there's an app for that that comes on most modern cell phones... "airplane mode".

[charger]

AH AH AH yeah but if someone have to call me ?