Smart-UPS SURTA1500XL powering Parasound JC1 monoblock amplifiers, overload on startup harmful?

[Anonymous user]

I have my SURTA1500XL hooked up to two Parasound JC1 monoblock amplifiers for my stereo, rated at 400W each. I don't play them very loud, at steady-state they show up as each using 30% load (2 lights on the load meter).

However, when I first turn on the amps, they spike the overload light briefly. Even turning on one amp will do this, the second amp briefly lights up the overload light and the APC also briefly chirps at me.

1) Does this activate the surge protection circuitry, and will repeated use quickly wear out my APC or its ability to protect my equipment? I turn on and off the stereo several times per day.

2) Will this in any way harm my amplifiers, or blow any of their fuses etc? Is not being able to draw the initial current spike somehow detrimental?

3) Would the initial current spike of the amps affect any other components plugged into the APC?

3) Will regularly running the APC at 80% load drastically reduce its life?

(note that with turning on the rest of my stereo equipment, the load meter goes up to 80% (5 / 6 lights))

I would like to keep my amps plugged in to the APC because of the online topology and clean power I can provide to the whole system, which significantly helps to improve the quality and depth of the sound output, I'm not that concerned that the batteries would only last a short while during a power event, but I'm just a little concerned about drawing that much current from the APC and the overload light.

Thanks for your help.

[Anonymous user]

I have my SURTA1500XL hooked up to two Parasound JC1 monoblock amplifiers for my stereo, rated at 400W each. I don't play them very loud, at steady-state they show up as each using 30% load (2 lights on the load meter).

However, when I first turn on the amps, they spike the overload light briefly. Even turning on one amp will do this, the second amp briefly lights up the overload light and the APC also briefly chirps at me.

1) Does this activate the surge protection circuitry, and will repeated use quickly wear out my APC or its ability to protect my equipment? I turn on and off the stereo several times per day.

2) Will this in any way harm my amplifiers, or blow any of their fuses etc? Is not being able to draw the initial current spike somehow detrimental?

3) Would the initial current spike of the amps affect any other components plugged into the APC?

3) Will regularly running the APC at 80% load drastically reduce its life?

(note that with turning on the rest of my stereo equipment, the load meter goes up to 80% (5 / 6 lights))

I would like to keep my amps plugged in to the APC because of the online topology and clean power I can provide to the whole system, which significantly helps to improve the quality and depth of the sound output, I'm not that concerned that the batteries would only last a short while during a power event, but I'm just a little concerned about drawing that much current from the APC and the overload light.

Thanks for your help.

[Anonymous user]

HI there,

You may already be aware of this but thought it worth mentioning that your Parasound Amps have a "soft-start" circuit utilizing NTC's (negative temperature coefficient resistors) to reduce the inrush current drawn by its toroidal power transformer and while charge the capacitors (4 x 33,000 uF), then a relay kicks in to bypass the NTC's for full input current. My comments / answers re your questions are:

Most of the smart-ups input/surge protection circuitry is designed to reduce harmful voltage spikes, not current spikes. There are inline inductors designed to filter out EMI/RFI noise on the incoming power but these are high current devices...Eg upwards of 22 Amps. Your Parasound Amps may actually generate a voltage spike when they are turned off as the magnetic field in the transformer collapses, but perhaps Parasound's engineers have included circuitry to prevent that from going back out on the line (Can't tell from the online searches I did)...any such spikes would hit the output circuitry on the UPS, not the input. Current flow within the ups does pass thru some relays (Eg Bypass / PFC ) which will have to handle a brief current surge, however with relays its more the make/break action that wears them out. When your ups chirps at you does it make any mechanical switching or clicking noises ? Once these UPS are overloaded, if its a sustained overload they will usually not kick to battery but could shut off as  a protective measure to prevent damage to the IGBT transistors in the UPS inverter/charger stages.

You say your load bar graph is showing 2 bars - this could actually represent up to a 49 % load, not 30%. If 4 bars are lit up that's 80% , 5 bars is 100 %.

The higher the load on your ups, the slightly shorter the lifespan of the batteries will be as the depth of discharge of the batteries during the 14 day self test (or actual power outage) is directly proportional to load....higher depth of discharge means shorter battery lifespan.

The SURTA1500 is capable of 1050 watts of real power output (not 1500), so to me it would seem like having these two high power Amps plus all your other gear is a bit too much. Your Amps can put out up to 800 watts into 4 ohms and 1200 watts into 2 ohms .... 400 watts is only at 8 ohms and no speaker maintains that impedance value over all input frequencies...between 20Hz and 20kHz it can drop lower than 8 or be higher. Repeatedly having the ups report overload represents an electrical strain on it that it wasn't meant to handle, so I believe over time some degradation of the UPS is definitely possible, but not the Amps.

If this were my setup I might put the Amps on a power conditioning device (surge arrest/noise suppression) but not a full blown UPS. Nothing wrong with having your source devices and preamps on a UPS though !

[voidstar_apc · Accepted solution]

1) A brief current overload may depress the line voltage depending on the magnitude of the surge and the conditions of your electric wiring, however this isn't a big concern. If the line voltage did go down, the UPS would go to battery briefly. I don't think such a voltage depression would significantly affect surge suppression... it's just not very much energy. Surge protection does wear out over time as it suppresses the surges from the power lines.

2) It will not harm your amplifiers. The overload indication is mainly to warn you that the UPS may not be able to sustain the load on battery, although SmartUPSes are designed to handle a brief overload. The easy way to test this is to pull the plug and see if the amps work while the UPS is on battery. You can also try turning them on while on battery to see if the UPS can handle the initial surge. The initial surge may not matter to you if you aren't turning the amps on during a power outage.

3) The initial spike of current shouldn't affect other components plugged into the UPS unless the wiring is soft enough that it depresses the voltage (which you can tell if the UPS goes on battery). And if it does depress the voltage, most devices should not care. No device should be damaged. For example, a laser printer on the same circuit will often depress the voltage enough when it starts to trigger a UPS to go to battery, but computers on the circuit are completely unaffected.

4) Running a UPS at high loads is APC's recommended way to operate them because it's more efficient than a UPS under low load. It should not reduce lifespan significantly, although like battman says, depth and frequency of battery discharge affects how long the battery lasts.