Apartment HVAC Causing Audible Pops Through System

Discussion in 'Audio Hardware' started by zombiemodernist, Jan 23, 2023.

  1. zombiemodernist

    zombiemodernist Forum Resident Thread Starter

    Location:
    Northeastern USA
    Hey all, been having an internment noise issue in my system (most audible in my phono rig due to gain) related to my AC/hot air blower kicking on/off as part of its regular operation. I was wondering if anyone here has dealt with something similar and could offer advice.

    As stated in the thread title I’m in an apartment and have little control over my environment. Currently my stereo is plugged into a Tripp-Lite IsoBar > outlet. Unfortunately this is beside the ancient thermostat controller and blower unit itself. When playing records (VM95ML>Darlington Labs MP-7>Yamaha A-S501) if the AC unit kicks on / off there is often a pop through the speakers about the volume of a moderate surface tick — pretty annoying.

    I used my cheapo multimeter and manually toggled the AC unit on/off measured some surging up to 135v+, and even in some instances browning out down to 113v on the outlet the stereo is plugged into, and all other outlets in the room on the line. I’m pretty certain this is the source of the issue but of course I’m unable to relocate the stereo. My main two options seem to be:

    - Run an extension cable about 40’ to the outlet in the back of the room which is on the bedroom’s line and doesn’t seem to fluctuate in voltage. Doesn’t seem ideal with the long cord but that way the stereo is isolated from the issue which would possibly seem to be a risk of damage. Unfortunately this outlet is switched and shared with a Roomba which also isn’t ideal.

    - Pursue some sort of isolation between this current line and my stereo, possibly an isolation transformer? I’m totally uneducated about these power conditioning / isolating products.

    Obviously welcome any and all suggestions but I’m primarily looking to treat the issue as pragmatically as possible, for this mostly mid-fi setup, no isolation esoterica in the budget. Thanks for any help!
     
  2. CoolJazz

    CoolJazz Forum Resident

    Location:
    Eastern Tennessee
    If it was happening to me, I'd start chasing by going to the breaker panel and tightening all of the individual breaker feeds. Tightening those screws.

    If that wasn't it, then I'd look at where the offending sources are as far as which buss and then compare that to the one feeding the stereo system. Try to get it away from and hopefully off of the one that gets surges. You should not be seeing that much change in voltages.

    CJ
     
  3. Bill Hart

    Bill Hart Forum Resident

    Location:
    Austin
    What type of heating/air con unit is it? Heat pump type that has a plug for power that is accessible? Is the unit housed in a panel?
    Iso transformers can buzz. But if you isolate the HVAC unit, depending on size, current demand, it could solve the problem. You don't necessarily want an iso transformer in your listening space. I have several. One, which steps down from 240 to 120 is fairly quiet, but in using it to power my tone arm air compressor, which created a really nasty electrical snap through the system, it blew through 20 amp fuses. It was a big compressor.
    Doing a dedicated line in an apartment is hard, and as I recall from past system set ups in other houses, no guarantee. See above example re the compressor, which also had available a dedicated line.
    I did solve the problem with a smaller iso transformer, but soundproofed the closet it was located in and downsized the compressor from 1 hp 13 gallon to 1/2 hp 6 gallon.
     
    zombiemodernist likes this.
  4. jfeldt

    jfeldt Forum Resident

    Location:
    SF, CA, USA
    I would run that extension cable for now, with a another counter direction cable for the roomba if you have to :)

    I’m sure some people will say a proper power supply is supposed to block any changes, but as you hear, they don’t block everything. With your DMM do you see any DC on either cold or hot in reference to ground? If so, a transformer is best there. Caps won’t help your sustained too high and too low voltage, but you could try some X rated capacitors across hot and cold to see if that helps with the pops. Something like a 1uF and a 47uF to start with…
     
    Last edited: Jan 23, 2023
    zombiemodernist likes this.
  5. Harris11235

    Harris11235 Forum Resident

    Location:
    Minneapolis, MN
    You might want to look into a UPS with a battery and an inverter. This will take the incoming power from the wall, convert it to DC and back to AC with a perfect sine wave. The battery is there to supplement power for short periods if the voltage from the wall drops out. There are different grades available, from residential to enterprise to medical.
     
  6. zombiemodernist

    zombiemodernist Forum Resident Thread Starter

    Location:
    Northeastern USA
    Yeah thanks — should clarify this. It's a system I haven't experienced before moving here so not sure of the formal term. We have two integrated windowsill units in the living room, and one in each bedroom, each with discrete thermostats but they are fed hot/cold from the building's common source at their discretion. Seems to be wired in the wall directly without a visible plug at least with cover removed. Pretty sure it's vintage to the 70s as is the breaker box and likely the breaker itself :shake:. Unfortunately they put every single blower unit on the same line as the living room receptacles (save that one in the back which is shared only with the first bedroom), and chained all the second bedroom (my office) onto it as well which I didn't realize until tracing it today.

    The more I think of it, the more I realize this is probably not the ideal line for the living room stereo anyhow, not only are the 4 blowers on it, but as the only power source in my office it often runs another stereo setup, my computer monitor and a high-heat Mercury Vapor Bulb for our pet tortoise for most of the day. I guess my minor concerns about a long run extension cord are worth disregarding to get the stereo off this very busy line.
     
  7. zombiemodernist

    zombiemodernist Forum Resident Thread Starter

    Location:
    Northeastern USA
    My girlfriend is a lab scientist and I have been joking that she should bring me home a medical grade one from work lol. Do you have any specific recommendations for what to look for? I know vaguely there's different types of inverters, not sure what specifically I'd want to start looking for.
     
    head_unit likes this.
  8. Harris11235

    Harris11235 Forum Resident

    Location:
    Minneapolis, MN
    Hah, play her One Piece at a Time for some inspiration.

    You want a UPS, which has a battery plus an inverter. The battery is what’s going to kick in to supplement power when you have brownouts. There are a bunch of options out there, but if I were buying, I’d look at Cyberpower or APC, then determine the model that supplies enough juice for your system and has enough outlets for all of your components. The medical grade Cyberpower units come in white, which might be more decor friendly than some of the other options.

    But first, I’d try to see if you can get your super to have the panel rewired.
     
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  9. Ham Sandwich

    Ham Sandwich Forum Resident

    Location:
    Sherwood, OR, USA
    If you try a UPS you'll need one that does a pure sine wave. The cheap UPS units do a square wave or stepped square wave to simulate a sine wave. And that's not good for audio gear. Audio gear is not designed to be run with that sort of power. So you'll need one that does a smooth sine wave. What's called a pure sine wave UPS.

    The lower cost pure sine wave UPSs are going to be line interactive style. A line interactive UPS only does the power clean-up and pure sine wave clean-up when it is on battery power. So only does the pure sine wave and power clean-up when you have a power outage. And that's not going to help you in your situation.

    What you'll likely need is a UPS that does double conversion, or what is also called an online UPS. With double conversion it is always running the power through the pure sine wave regeneration, even when relying on the electricity from the wall outlet. A double conversion UPS is going to do a better job of cleaning up the power and reacting to the brown-out sags than a line interactive UPS. A double conversion UPS will be able to filter out line noise while a line interactive UPS won't do any better at that filtering than your Tripp-Lite IsoBar.

    Here's an explanation of line interactive vs double conversion: Line Interactive vs. Double Conversion UPS – Which One’s Best? - Quality Power Solutions

    Unfortunately the UPSs or power management devices that do double conversion are quite a bit more expensive than the line interactive versions. A good line interactive pure sine wave UPS with enough power to run a stereo is around $250. While a similar double conversion UPS is around $1500.
     
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  10. zombiemodernist

    zombiemodernist Forum Resident Thread Starter

    Location:
    Northeastern USA
    Thanks for the links and the thorough explanation. That’s sort of as I feared, a true power conversion system to purify the fluctuating mains was going to cost more than I’m able to invest. Based on those readings I’m fairly certain a standard computer consumer grade line-interactive UPS wouldn’t do much for this issue.

    Unfortunately building maintenance is so ineffective they’ve made matters worse in the past, and management is tight-fisted, so the chances of them wiring the blowers to their own line at my request are zero.

    For now I think I will source a decent appliance grade extension cord and tap the rear outlet for power, see if that mitigates the issue.
     
  11. Lowrider75

    Lowrider75 Forum Resident

    Location:
    Philadelphia, PA
    How many circuit breakers are in your service panel and are they labeled?
     
  12. zombiemodernist

    zombiemodernist Forum Resident Thread Starter

    Location:
    Northeastern USA
    Eight, though two are bridged for the range, so I guess seven lines. Attaching a photo of the antique below. Hi-Fi is on breaker 4 at the moment. Despite only being labeled "Living Room Receptacles" toggling it also cuts another bedroom receptacles and all four blowers, so they must be on the line as well.

    The best idea so far seems to be to extend the Isobar's lead to the rear outlet that will place it on breaker 8. Breaker 8 has a Roomba, a couple of lights, a phone charger and a TV that almost never gets used so a lot less of a party there. Probably the lowest load in the house, closest I can get to dedicated line as a renter. Putting my DMM in voltage meter mode on the outlets connected to Breaker 8 I don't noticed spikes/dips in voltage from the AC blower kicking on/off like I do on the breaker 4 outlets.

    [​IMG]
     
  13. Lowrider75

    Lowrider75 Forum Resident

    Location:
    Philadelphia, PA
    Sounds like a plan. The one potential issue is lighting. Track lighting and the use of dimmers will cause noise on the audio line.
    Will you do the work or call and electrician?
     
  14. zombiemodernist

    zombiemodernist Forum Resident Thread Starter

    Location:
    Northeastern USA
    Probably chose the wrong words, can't really do any real electrical work without the authorization of building management who are very unsympathetic to anything not causing an immediate electrical fire.

    I was thinking of swapping the power strip I use now with the same model just with a 25' lead, unless that would cause major issues for the setup. The 25' run with a raceway guiding it can get my stereo power from the back of the room on breaker 8. Ideally the place could be re-wired — we have a few electricians in my GF's family but I don't want to get anyone in trouble with the management company.
     
  15. zombiemodernist

    zombiemodernist Forum Resident Thread Starter

    Location:
    Northeastern USA
    Well so much for my quick fix. I tried a daisy-chained extension cord to the discussed outlet (I know, not ideal) and the blower noise can still be heard through the phono stage. Seemed to somewhat muted in intensity, but I didn’t measure the peaks objectively. Might just be my confirmation bias b/c I didn’t notice any major voltage swings with the DMM.

    Anyhow seems likely the issue is going to be present throughout my apartment. So sort of back to square one. Is a double converting UPS really the only thing that could isolate me from this issue outside of an apartment-wide rewiring?
     
  16. noway

    noway Forum Resident

    Location:
    Ontario, Canada
    What happens if you disconnect everything phono related from your system and use a source like CD player to test? Do you still hear noise?

    What if you put it on breaker #1 by removing a light bulb from a fixture near your audio and plugging your audio system into one of these?
    https://www.amazon.com/GE-Polarized-Adapter-Install-54276/dp/B002DN6QX2/
    Disclaimer: this is a 2-prong adapter and I am not an electrician so you should consult with one before trying this!
     
    Last edited: Jan 24, 2023
  17. Lowrider75

    Lowrider75 Forum Resident

    Location:
    Philadelphia, PA
    Daisy chaining not good but you know that. The problem with your service is even though breaker 8 is a separate circuit, all the AC lines meet at the panel and share the ground buss and the neutral. So each circuit is affected by the HVAC.

    If @jea48 can check in, he might have a solution.
     
    Last edited: Jan 24, 2023
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  18. zombiemodernist

    zombiemodernist Forum Resident Thread Starter

    Location:
    Northeastern USA
    Yeah all sources sadly, most only noticeable at absurd SPLs. Likely due to the high gain the phono chain is annoying at normal listening levels though, sounds like a light dust tick almost. Noise is also pronounced on the Yamaha’s internal phono stage, perhaps a bit quieter but it also has less gain so that’s not really a surprise.

    If it helps narrow this down for anyone I also hear this on my office setup (gear in profile). This setup is also on breaker 4 — thanks to their bad labeling I didn’t realize this till recently. Oddly enough the Blower in the office doesn’t cause it — the bedroom one does. Not sure if the living room offender can be heard in both systems. Based on this not sure if it’s a proximity issue as well. But I’m inclined to think something is just wrong with these blowers and they’re mucking all power taps in the place.
     
  19. AP1

    AP1 Forum Resident

    Location:
    TX
    This is probably the only option left for you. But you should be happy to know that industrial grade double conversion UPS is still cheaper than audiophile grade power cleaning device from makers like PS Audio.
     
  20. AP1

    AP1 Forum Resident

    Location:
    TX
    Do you hear noise constantly while blower works or only when it starts? Some AC units may have motor that create radio interference picked up by phono preamp or interconnect. Solution for that problem is different from having power cleaned.
     
    Shawn likes this.
  21. jfeldt

    jfeldt Forum Resident

    Location:
    SF, CA, USA
    I was thinking the same thing. OP, do you have an oscilloscope you can borrow from someone?
     
  22. zombiemodernist

    zombiemodernist Forum Resident Thread Starter

    Location:
    Northeastern USA
    No apparent “running noise” thankfully as it needs to run a lot this time of year. Only noise when it’s kicking on/off from the basic manual thermostat. Same goes for the voltage fluctuation I saw on the DMM, the swing up or drop is momentary before mains stabilizes to 120v. Coincided with the “pop” exactly. Does this indicate a momentary RF issue? I’m running Mogami shielded coax in the phono rig on both systems if that’s relevant.

    Not 100% sure but I may be able to ask extended family that works in the field. What would I be looking for, the signal coming from the phono stage?
     
  23. Bill Hart

    Bill Hart Forum Resident

    Location:
    Austin
    This is what was happening when the 1 hp compressor that I used with my tone arm kicked in. Even with dedicated lines. That's where the iso transformer came in- not for the system but the compressor. (Which I eventually replaced with a smaller one).
    Old HVAC motors are going to throw off nasty junk. Somebody who knows electric motors can explain it. I'll think about solutions since you don't have much flexibility given the rental, age of wiring and HVAC equipment.
    Back soon,
     
    Last edited: Jan 24, 2023
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  24. AP1

    AP1 Forum Resident

    Location:
    TX
    In that case you need to split HVAC and audio system on different branch circuits. Though it may not solve the problem completely and require double conversion UPS. Do you notice any lights dimming when blower starts? If so, you may call electrician to investigate, as this can be a symptom of potentially serious wiring problem.

    I do not think that blower motor is very powerful, but for something like heat pump there are soft start devices. They significantly reduce motor start current. I use them for my AC compressors.
     
  25. Bill Hart

    Bill Hart Forum Resident

    Location:
    Austin
    Is it possible to simply shut off (by thermostat setting or otherwise) the HVAC units when you are doing your listening? There were a few appliances in our previous house that if turned on when I was listening could cause noise. Simple answer was not to use those during listening sessions. (One was a convection oven, another was a low voltage light in the kitchen--on the main floor where my system, with dedicated lines, was on the third floor).
     

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