Having a problem when HVAC system turns on and cuts my system off!

Ok here’s the deal smart Agoners. I have been in this new house with pretty much the same rig with no issues for a year or so. I play music pretty much all day now in our living room space that opens up to the kitchen. Several times throughout the day, not every time, when the HVAC system turns on it will cause my computer server usb connection to the dac to fail. Usually a few seconds after the HVAC turns on the USB signal is lost.....cuts out?

My system is on a dedicated 20 amp line with two levels of conditioning before the dac and computer server. A BPT balanced conditioner feeding two Core Power Technology balanced conditioner/cords to my system. See my virtual system for a better understanding.

I have have to turn off the dac and turn it back on to re-initiate and play music again. My dac is built into my amp just as an FYI. What the heck is going on and what is the fix?

Must be some kind of electrical surge or such that is somehow impacting my direct AC line and system. Strange. Happening more often of late.

6017afa4 4738 4a9a bf4c 2da38b5f3955grannyring
Again it happens perhaps 5 times a day, but the HVAC unit turns on far more often than that so this issue is sporadic at best. Seems to be happening more however. 
So your running a USB connection from your computer directly to your amp (which has a built in dac)? NOT GOOD! I advise you Isolate your computer from the amp/dac by using the optical output of the motherboard (hopefully it has one) then into a DIP (Monarchy audio sells these),this allows you to use a XLR or RCA digital out to the amp/dac so that it is now totally isolated from the computer, it is also a jitter reducer and much more! You can read about DIP’s here:



Matt M
The Lyngdorf 2170 is made to specifically use the usb input built into it. It is really not a dac as the signal stays in the digital realm right up to the point it hits the output to the speakers. That is not the issue. Also, I have a IFi Micro USB 3 filter/reclocker between the Computer output and Lyngdorf.

It just happened again. The music stopped playing over the speakers even though the song continued to play on the server. Somehow the HVAC is cutting off the signal through my computer - iFi Micro USB 3 - Lyngdorf. These are all connected by two usb cables. This time I simply hit pause and play again to resume the music. So darn strange.

Adding more detail for you all, both the USB output card on my computer server (SOtM) and the iFi Micro USB 3 are powered by 9vdc linear power supplies. I checked both LPSs and they are outputing 9 vdc as they should. Both LPS units are plugged into the BPT conditioner.  Something tells me perhaps they are not happy when the HVAC turns on at times?
Hi Bill,

Strange problem indeed, especially given that it wasn’t present for a year or so with essentially the same system.

I don’t think we can say at this point whether the problem is caused by interference from airborne RFI or by effects of the HVAC on the AC power. Or whether what may have changed or degraded relative to when the problem didn’t exist is in the audio system or the HVAC system.

The only suggestions that occur to me at this point would be to perform the following experiments:

1)See if the problem occurs with the iFi reclocker removed from the system.

2)If you have power supplies that can be temporarily used in place of the two 9 volt linear supplies you mentioned, give them a try.

3)If practicable, try to determine if the problem occurs when the volume control on the 2170 is turned all the way down. Perhaps some circuit point in the 2170, or a cable that is connected to it, is picking up airborne RFI when the HVAC system turns on, which is then amplified by the power amp section of the 2170 and in turn inducing a transient at an upstream circuit point.

4)Determine if the problem occurs when the HVAC system turns on for heating purposes, for cooling purposes, for fan only purposes, or for some combination thereof.

Good luck. Best regards,
-- Al

The HVAC might be causing a ground differential when kicking on.  Try grounding the Lyngdorf chassis to an external ground.

I think you are onto something. Please give me some external ground options. I assume the outlet plate screw won’t qualify?

No doubt the issue is linked to the turning on of the HVAC unit as there is a 100% correlation.

@almarg The volume has no impact. HVAC for heating is the cause right now. I think you are right to suggest pulling out one LPS at a time to test.

Thanks guys! 
Depends on the design of the outlet & outlet box. This theory could be tested by running a ground wire to the plumbing. But, it won’t work if it's PVC. Is there an external ground lug on any of your power conditioners?
I had something akin to this happening with my computer feeding USB to my Lampizator Golden Gate DAC, where every time the AC kicked in the music stopped for ~ 5 - 8 seconds, but then it would reestablish connection and continue.  Of course that gap drove me nuts!  Worse yet, it wasn't just my AC, but also my many neighbors' AC systems that triggered this event.  I'm guessing a momentary power line sag occurred from the start up capacitors in the AC systems.

I tried a Topaz isolation transformer on the line, both in normal mode and in balanced mode, and it did not help.  What did solve this problem for me was to try a PS Audio P-10 power regenerator.  This stopped the maddening interruptions that I was suffering, and it actually sounded almost as good as my best power feed set up (Topaz in balanced feeding a very expensive power cord feeding an equally expensive HB Marble power distribution bar).  Now I have enjoyed continuous play for 18 months and counting.  It might be worth a try in your system (and might give your system's sound quality a boost, too).
I still say your not isolating anything unless you get rid of the USB and go Optical from the computer. All these isolation devices dont help.

Thanks all. I did two things that may have cured the issue. 

- the iFi Micro USB 3 has a grounding switch.  Manual says to defeat it and cut the ground. Well, instead I decided to engage the ground switch 

- I plugged one of my LPS units in a different BPT conditioner outlet

It has not happened since.  Hope this is it!
Well it started up again at 6pm. I will remove the IFi next to see if it stops. 
Stick a voltage meter and see how much it sag. Might want to clean out computer power supply as well. 
Hey Bill. I hope all is well . Do you have a meter that you can put on the outlet that the Golden Gate is plugged into . I would be willing to bet that you are getting a voltage drop when the A/C kicks on.I would bet that the Line Conditioner is the one that causes the drop out .I am guessing that the Lampi is plugged into the conditioner .. right ?
Have you tried plugging the Lampi and or PC directly into the outlet ? Are you running the conditioner off of the dedicated outlet .I would try to bypass the line conditioner. I would bet that it is the culprit...... ????
Good Luck
Hi grannyring,
  I remember an episode of "This Old House" on PBS where they did a feature of a startup business. The business was about a system that kept track of what was happening with all the breakers in electrical panel in a home. Each conductor on each breaker had a current transformer (CT) on it. The CT's sent current draw info to a computer which had a program that recorded what was happening and kept a log that could be reviewed many months later. You could see when a motor was energized and how much the surge current was along with how long it lasted. By having a history of every breaker you could tell when things were running normally and when things started malfunctioning. They said that when things start having problems it may be long time afterwards before it becomes noticeable. That could be anything such as a hot water heating element or washing machine malfunctioning. That being said my guess would be your problem could very well be your hvac unit. If it turns on and there's much not much going on electrically in the household then it may not be enough to trip out you equipment. It could also be that something else is malfunctioning and the hvac coming on is enough to trip the conditioner. That would explain the intermittent problem. You mentioned that everything worked fine for a year so something has changed. I think we all could use one of those monitoring systems. Hope this helps.
Every time my washer started a new cycle, I would get a thump out of my subwoofer due to the drop in voltage.  Essentially, the voltage dropped enough so that the amp in the sub did an off / on cycle which caused the thump.

I needed something to support the AC feed very briefly -- for the fraction of a second that the voltage dips.  My solution was to get a UPS.  I did not need a high capacity expensive one that would support my system for hours; I just needed one that could bridge my voltage gap for a fraction of a second.

There are many.  This one worked for me --

Stick a voltage meter and see how much it sag. Might want to clean out computer power supply as well.

This is the first thing I would try as well, you will need an old sweep style meter to see what’s going on, if anything.

Also, you may have a bad starter cap on the HVAC.

same issue. Problem went away after the gas ignition module was replaced when it failed. Lenox furnace circa 2001
Grannyring, Did you ever figure out your problem? I would be interested in what the solution was.