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Bottlehead Kits => Crack => Topic started by: jmacinnes on September 16, 2020, 09:00:11 AM

Title: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on September 16, 2020, 09:00:11 AM
Hi all,
I'm trying to track down the source of this regular, periodic low-pitched chirp (the best I can describe it is like the sound of a small, tight zipper being zipped up really fast).

• it's very regular, always about 12s in between chirps. Each chirp is short, say 250-500ms.
• it's loud enough to be irritating, but not affected by adjusting the volume pot
• predominantly in the left-channel; present, but fainter in the right
• successive chirps are always about the same loudness, but somedays it is louder than others.
• it's present when unplugging the RCA inputs, so it's not coming from the DAC or computer.

This is a Crack w/ Speedball, and I'm listening through Sennheiser HD650's. I first checked all of the voltages, and reflowed any joints that looked suspect. I'm now wondering if it could be something in the outlet or interference from something else. I confirmed the outlet was grounded, but not sure what to test next.

Has anyone heard of a similar issue before? Or any ideas about where to look next? Thanks!
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Paul Birkeland on September 16, 2020, 09:22:02 AM
This is likely interference from something close by that's a wireless device (phone, router, etc).
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on September 16, 2020, 10:38:30 AM
Thanks, Paul! I just turned the wi-fi and bluetooth off on my phone, ipad, and laptop, and moved them all downstairs to a far room, but still getting the chirps. The router is downstairs as well, beneath the room the Crack is in. Later this afternoon I'll try to shut the router down and see if that changes things.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: mcandmar on September 16, 2020, 11:32:17 AM
Do you have a UPS or other battery based backup system anywhere in the house?     I have heard them produce a noise like that, specifically APC units. I think its something to do with the battery charge circuit giving a pulse at a fixed interval.  Very annoying if you have one in your office, once you hear it you cannot un hear it.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on September 17, 2020, 07:12:59 AM
Removing all devices and shutting off the router downstairs didn't make a difference. I moved the crack to different outlets around the house, and the chirp occurs on any outlet connected to the original circuit, but not other circuits. These outlets are all in the same region of the house, so I suppose that doesn't rule out interference in the area from some other device, but I'm hard pressed to think what that might be. To test whether its interference or something in the circuit, maybe I can try plugging an extension cord into the original outlet and running it to an area of the house where there's an outlet that the crack doesn't chirp at, and testing it there.

No UPS on this circuit (or anywhere else that I know of), mcandmar, but your suggestion of a battery backup system gave me hope it might be coming from the wired smoke detector in the room. But alas, removing it from the circuit didn't do anything.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Deke609 on September 17, 2020, 07:29:35 AM
What else do you have plugged into or powered by that same line?  You can figure that out by flipping the breaker that controls that outlet and checking to see what else is turned off.

cheers, Derek
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Paul Birkeland on September 17, 2020, 07:45:14 AM
Try turning your phone all the way off.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: watonwak on September 17, 2020, 08:55:29 AM
It sounds exactly like interference from my phone when its connecting via mobile data. When i enable WIFI calling on my phone it goes away.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on September 17, 2020, 02:02:54 PM
Still no luck tracking this down, but more evidence that it's interference and not coming from the outlet/circuit.

• I shut down all phones, computers, tablets, and unplugged or took the batteries out of any "smart" device throughout the house. Unplugged everything else on that circuit (just a few lamps, and a turntable, receiver, and tuner, all of which haven't been on during other tests). Still chirping.
• Chirps seem dependent on location. It chirps when keeping the amp in the same location, but powering off of different house circuits. Conversely, there are location near outlets on other circuits in the house where it doesn't chirp, and if I run an extension cord from the original outlet to this location, still no chirps.
• I walked out a rough grid on the floor of the office where I'm set up, and the chirps are definitely louder near the outside wall of the house. It varies in intensity at different locations, but not in any other sort of pattern that I could figure out.

For what it's worth, my home office is on the 2nd floor of a 100+ y.o. house in a relatively dense neighborhood (Phinney/Greenwood in Seattle, for anyone who knows it). Powerlines maybe 40' out the window, and a neighbors house ~20'. Pigeons right outside the window, but they don't appear to be radio collared. I don't know, stabbing in the dark here about what the source of interference might be.

I'm on a mission to figure this out now. But I guess the more practical question is: is there anything I can do about it (short of moving my office to a different part of the house)? Is there anyway to shield the amp, somehow?
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: oguinn on September 17, 2020, 03:26:00 PM
Try this

https://forum.bottlehead.com/index.php?topic=11676.0
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on September 18, 2020, 06:21:57 AM
Thanks for the tip! Looks easy enough. I'll order those diodes and give it a shot and report back.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on September 23, 2020, 08:58:53 PM
Shoot, sorry to say that adding the ground breaker mod didn't have any effect on the chirps. For 11 seconds I was really hopeful.

Assuming the amp is picking up interference, what kind of combination of signal strength and distance from the amp could produce this sort of effect? My sense was that interference from a device like a computer or phone would have to be reasonably close to the amp, but after shutting down devices throughout the whole house I'm still racking my head over what the source could be.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Deluk on September 24, 2020, 12:59:08 AM
Do you have battery powered smoke alarms that have an auto self test circuit? Have you tested the Crack in another house or location?
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on September 25, 2020, 08:56:25 AM
There is a set of 5 wired-in smoke detectors with battery backups throughout the house, but I disconnected them all to test, and still chirping. There are locations around the house where I can move the crack to and not hear the chirps.
I should also mention that this is a new phenomenon that started once I moved into this new place. Previously, I've had the crack for ~2 years in a different house with no issue. The crack's new room is set up almost exactly the same as the old room in terms of placement relative to laptop and stereo receiver, etc.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Paul Birkeland on September 25, 2020, 08:58:48 AM
The knowledge that other places in the house remove the chirps is helpful.  It may be that you need to swap the circuit branch that feeds where you plug in the Crack to the other half of the breaker box.  Still, if you're in a single family home, you should be able to shut stuff off and eventually find what's polluting the line.  You may find that shutting off one breaker at a time on your panel may be what it takes to figure out where the polluting device is connected.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: ludddite on September 26, 2020, 11:00:23 AM
You mentioned pigeons, and the first thing that popped into my head is that one of your neighbors might have a bird x or some other type of pest control running. I don’t know how you would confirm this other than talking with them.  Just a thought.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Deluk on September 27, 2020, 02:33:24 AM
This is a bit off the wall and I can't be too specific but I have read of a using a small AM portable radio tuned to a non station position with the volume up full and use it as a receiver to pic up the signals. Chase the noise. Anyone want to comment?
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on October 09, 2020, 09:09:50 AM
Waited for my partner to be away, and then spent a couple of days running up and down stairs flipping circuits. Here's what I'm learning:

More evidence that the chirps are caused by interference. Location within the house (upstairs, specifically) is the only variable that seems to change anything. There are 2 circuits upstairs (lets just call them A and B).
• chirps when the amp is plugged into A and the breaker for B is switched off.
• chirps when the amp is plugged into B and the breaker for A is switched off.
• no chirps when the amp is plugged into a different circuit downstairs (C) but along the same wall of the house.

The source of the interference isn't on the house's electrical
• chirps when the amp is plugged into A (and to the best of my knowledge, is the only thing plugged into A), and I switched off every other breaker in the house, one by one

Next thoughts are:
• there's an obsolete phone line and coax cable running up the outside of the house. There shouldn't be signal going through either, but worth ripping down anyway?
• try to see if I can rent an RF spectrum analyzer or something to at least get a clue on the source based on what frequencies the interference is coming in on? I have an AM tuner next to the amp, and I cycled through the frequency range on it, but never heard anything resembling the chirps.
• talk to neighbors about any pest control thing.
• Too uninformed to know if this is foolish, but is it worth building a small faraday cage out of some screen mesh to place the amp in? Or does the fact that I'd still have to run power through the cage totally negate any effect it would have? Grasping at straws...
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Paul Birkeland on October 09, 2020, 09:33:57 AM
On your beaker panel (I'm going to assume you are in North America), are the breakers for A and B next to each other?  If they are not, are they on the same side of the panel?  How many breakers are between them?

It's still possible that A and B are running off the same half of the feed and C is on the other half, in which case this is still a fixable problem.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on October 09, 2020, 10:03:50 AM
Oh interesting, yes in fact, A and B are on the same side (left), with no breakers between them, and C is on the other side. Would it be helpful to know if there are chirps with the amped plugged in to any circuit on the left side? Looks like there are 2 other breakers on that side that power outlets in other (non-upstairs) rooms in the house.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Paul Birkeland on October 09, 2020, 10:19:04 AM
The way panels generally work is that two breakers that are right next to each other will be on separate branches of the main feed.  This lets you slot in a 240V breaker to feed a water heater, range, dryer, etc. and conveniently get 240V wherever you put a double wide breaker.

Since A and B are right next to each other and you have quiet operation elsewhere in the house, this is good news in a way!  It does still suggest that there is a source of noise causing these issues that has not yet been determined, but it isn't pollution coming from the power company at least. 
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Deke609 on October 09, 2020, 10:33:04 AM
To rule out the possibility that external interference is just particularly bad in your upstairs, you could run an extension cord from line "C" to upstairs and plug the crack in, putting the crack in one of the spots where you previously got the chirps on line "A" or "B".

cheers, Derek
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on October 13, 2020, 09:28:26 AM
The way panels generally work is that two breakers that are right next to each other will be on separate branches of the main feed.  This lets you slot in a 240V breaker to feed a water heater, range, dryer, etc. and conveniently get 240V wherever you put a double wide breaker.

Since A and B are right next to each other and you have quiet operation elsewhere in the house, this is good news in a way! 

Ah, was hopeful there for a second that moving the breaker to the other side might fix it. But happy to be ruling out potential causes all the same!

To rule out the possibility that external interference is just particularly bad in your upstairs, you could run an extension cord from line "C" to upstairs and plug the crack in, putting the crack in one of the spots where you previously got the chirps on line "A" or "B".


Thanks for this suggestion -- I tested this over the weekend, and I think the evidence is pointing toward external interference. I plugged a 100' extension cord into "C". When I'm downstairs, no chirping. When I go upstairs, I get the chirps. Moreover, it varies in volume based on my location upstairs. Not a huge space (2 rooms and a hallway, ~300 sq ft total), but I can hear the chirping anywhere upstairs, and it is:

• quietest when I put the amp on the ground
• louder at waist/desk level
• loudest of all when I hold the amp over my head and place it near the south wall.

The south wall has 2 old phone lines (no signal, as far as I know) and a fiber optic line coming into the house from the street. However, those lines first hit the house below the upstairs, and my sense was that fiber optic wasn't likely to emit interference due to light and all that (true?). I've read about interference in the context of a nearby wireless device, where you hear intermittent noise as the device is transmitting/receiving. So I'm baffled about what a source of interference could be that is causing such a regular, consistent pulse, and a strong signal that's detectable over a wide area of the house.

Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Paul Birkeland on October 13, 2020, 09:43:03 AM
Hmm, what WiFi enabled devices are up there?  Any cell data enabled devices? Anything unusual in the attic?
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on October 13, 2020, 10:28:00 AM
Typical wifi and cell data devices near the amp (phone, laptop, etc), but I've tested shutting everything down (these devices, and also all other devices throughout the whole house) and it didn't have any effect. In my last place, I kept the same devices next to the amp and never had an issue.

No attic, but a few months ago I redid the closet in the office, and saw an old galvanized pipe of unknown purpose running vertically in the south wall between the drywall and the siding. That's the only odd thing I can think of.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Paul Birkeland on October 13, 2020, 11:01:44 AM
You can also try fitting an aluminum tube shield over the 9 pin socket.  The add on ones will take the place of the socket retainer ring that comes with the stock kit.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on October 13, 2020, 11:18:43 AM
Awesome, thanks, I'll give that a shot! So something like this? https://www.thetubestore.com/belton-tube-shield-for-9-pin-tubes

In the meantime, can I DIY one out of cardboard wrapped in aluminum foil to test?
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Paul Birkeland on October 13, 2020, 11:22:46 AM
Yes, that will fit.

You can just use foil, you don't really need the cardboard.  Just make sure the foil touches the chassis plate well.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on October 20, 2020, 06:34:57 PM
9-pin tube shield arrived and installed, but no difference, unfortunately.

Assuming there's nothing else plugged in to circuit "A" that could be causing the interference (I still hear the chirps when "A" is the only breaker switched on in the whole house), seems like the interference is coming from something outside my house (could that also be why it's loudest near the outer wall and higher toward the roof?). As far as I could tell the amp was the only thing plugged into "A" when I was testing, but I'll flip all of the breakers off except "A" and check the meter outside just to be sure.

If it is coming from something outside my house, seems like my only option is to shield the amp somehow. Are there any additional shielding options beyond the shield for the 9-pin that I should try out?
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Paul Joppa on October 20, 2020, 07:51:00 PM
You can try a jellyroll pan - hold it close (5 inches?) to the amp and between the source - a crude direction finder!
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: larcenasb on October 23, 2020, 06:23:46 AM
Hahaha, such an awesome and resourceful suggestion, Mr. Joppa!
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Deluk on October 24, 2020, 12:50:12 AM
Do you know anybody who has a mini Honda generator to provide you with power? Desperate measures! Not sure if you have taken the Crack to another location for a cross check that way.
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Deke609 on October 24, 2020, 03:27:57 AM
Another cheap experiment: wrap the wooden base a few times in aluminum foil, and tuck the last 1/4 inch of the last corner of the foil wrap under a corner of the metal chassis plate (but NOT at the corner with the IEC inlet). This will form a shield of sorts that can drain to house ground via the chassis plate.

If the foil experiment helps, you could buy some copper film tape and line the inside of the base, including the narrow lip/shelf of the base that supports the chassis.

cheers, Derek
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: jmacinnes on October 24, 2020, 10:02:13 AM
Actually, the jellyroll pan was a pretty good idea. I grabbed a heavy duty 9x13" one, and if I hold it over the Crack like an umbrella (tilted just a bit toward the west south west) it seems to block the chirping almost entirely! I can only assume this means the signal is coming from the mothership locked in geosynchronous orbit somewhere up in that vicinity, but I'm much more interested in enjoying my amp again than in deciphering whatever message they're trying to send me ;)

I'm going to try wrapping the base in foil too, like you suggest Derek. If that works just as well, the copper film tape will be an elegant solution. If not, gonna buy a few more jellyroll pans and break out the hacksaw to build an enclosure for the amp to live in.

Really appreciate all of the help and suggestions in tracking this thing down (and more importantly, ideas for how to block it)! Can't tell you how much the chirps have been driving me mad!
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: Paul Birkeland on October 24, 2020, 03:26:18 PM
They're trying to communicate with you...
Title: Re: periodic chirp (or squeak?) every ~12 seconds
Post by: 2wo on October 24, 2020, 06:11:18 PM
Better get out your tinfoil hat...John