@jean-paul :
During last 2 decades I repaired several UPS's Eaton, Lunar, Emerson, etc. and I see in the scope the output waveform wirh my own eyes. Except for a residual carrier noise, the sine looks perfect.
During last 2 decades I repaired several UPS's Eaton, Lunar, Emerson, etc. and I see in the scope the output waveform wirh my own eyes. Except for a residual carrier noise, the sine looks perfect.
That is a cheap one. You will be surprised when you know what these cost straight from the manufacturer.
Yes, it should be good also with load. This is a essential requirement for some applications. The spec of the WHAD 1000 is 1% thd at 100% load, as example.
no: the spec is valid for non linear load with pf= 0,7. You can supply a small server rack HVAC unit with this kind of UPS. It is a easy goal for today high frequency inverters. There has been a incredible progress on power inverters on the last decade, A while ago it would have been impossible to reach this performance for a small UPS at 700-1000 euro price point such as this one.
Do they beat simple well filtered mains voltage to the average audio setup?
Now a Piller or Hi-Tec rotary/dynamic UPS would be an alternative
BTW recent online “direct drive” so transformerless UPS systems with advanced technology inverters operate in eco mode often to obtain very high power efficiency. That means they are normally in bypass mode and the inverter “starts” to supply the load within 1 ms when a brownout/blackout occurs. Also high frequency mechanical noise and their cooling fan(s) makes their use for audio IMHO a bit pointless. Don’t get me started about lead acid batteries in a normal home. For low power applications like audio it is doing simple things a complex way with many undesired side effects but each to their own of course.
Now a Piller or Hi-Tec rotary/dynamic UPS would be an alternative
BTW recent online “direct drive” so transformerless UPS systems with advanced technology inverters operate in eco mode often to obtain very high power efficiency. That means they are normally in bypass mode and the inverter “starts” to supply the load within 1 ms when a brownout/blackout occurs. Also high frequency mechanical noise and their cooling fan(s) makes their use for audio IMHO a bit pointless. Don’t get me started about lead acid batteries in a normal home. For low power applications like audio it is doing simple things a complex way with many undesired side effects but each to their own of course.
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@jean-paul :
Yes, a dummy load composed of 12 quartz heaters 600W each (220V), like one of those inside this one
Yes, a dummy load composed of 12 quartz heaters 600W each (220V), like one of those inside this one
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I agree with Jean-Paul, it is a wasted effort to use a UPS, where is the necessity of uninterrupted music?
Just put a good mains filter in series with the power supply.
Unless of course, you are having mains power issues, or are off the grid, with solar or wind, or whatever as the source of power.
Basically mains in to battery, and back to mains out, with lots of circuit in between, and those are likely noise sources.
Bear in mind amp loads change with the music, and if the UPS has automatic power factor controller, it may oscillate, or worse.
Just put a good mains filter in series with the power supply.
Unless of course, you are having mains power issues, or are off the grid, with solar or wind, or whatever as the source of power.
Basically mains in to battery, and back to mains out, with lots of circuit in between, and those are likely noise sources.
Bear in mind amp loads change with the music, and if the UPS has automatic power factor controller, it may oscillate, or worse.
A mains filter is a capacitor in parallel with the mains with another two connected to L, N and the other ends to earth. As far as I remember, this is followed by an inductor with zero resultant magnetic field under normal conditions. The zero magnetic field becomes non-zero when the L and N currents are not equal. This happens for asymmetric interference currents. Another capacitor follows the zero field inductor which usually has a voltage dependent resistor which conducts appreciably when the voltage across it exceeds a certain value.NareshBrd said:
Thanks goes to all respondents who took some of their time to reply and give their experience and opinions. Reading the thread suggests a good quality true sinewave UPS can offer some advantages, but overall, the added complexity is not justified as this is audio and audio does not need to be uninterruptible, unless it used for a live music event in the open air. In the latter case, generators are preferred given such events are often organised over large open grounds.
A non solution for a (small/non) problem.
That complex piece of switching equipment will create far more noise than the feared/imagined line noise.
Amplifiers are not fed Mains (surprise surprise) but rectified and filtered DC.
Sometimes even regulated DC, go figure.
Use/waste your efforts there instead of somewhere else, for far better results.
That complex piece of switching equipment will create far more noise than the feared/imagined line noise.
Amplifiers are not fed Mains (surprise surprise) but rectified and filtered DC.
Sometimes even regulated DC, go figure.
Use/waste your efforts there instead of somewhere else, for far better results.
Some posts removed. Keep it civil or we will take it further.I agree that most modern amplifiers don't suffer from electromagnetic interference - this is actually a requirement. The worst that can happen is mechanical hum from the toroidal transformer due to mains DC component. Latest models have a switching power supply so they are more likely to be the source of the mains noise rather than the victim. But the original poster did not specify what kind of power amplifier does it have. Vintage amplifiers that predate modern EMI regulations may have issues. The power transformer blocks most of the mains noise, but the primary side wiring was not segregated from the secondary wires; it was very common to make a bundle between primary and secundary and this may induce capacitive coupling of the mains radio frequency noise. Some kind of filtering is useful on this case.
Also, please remember transformer core hysteresis causes a lot of noise to be absorbed, the core acts as a choke in some ways, you can check with a scope. There is not enough current induced by noise in the secondary by short lived noise.
And rectifier and filters absorb the noise further, before it gets to the signal path.
The best solution for line noise will be a medical grade isolation transformer, or a regular one.
Failing that, many ready line filters are sold at prices that make you decide not to bother to make your own.
Or, as above, run your amp from a DC source, as in battery or old style motor - generator set.
And rectifier and filters absorb the noise further, before it gets to the signal path.
The best solution for line noise will be a medical grade isolation transformer, or a regular one.
Failing that, many ready line filters are sold at prices that make you decide not to bother to make your own.
Or, as above, run your amp from a DC source, as in battery or old style motor - generator set.
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I experience some power cuts through the day. And have been contemplating a double conversion UPS to keep the system alive till the Diesel Generator kicks in.
Is a good double conversion UPS with unity power factor(something like the eaton 9px) still not good enough for high current amplifiers? If the UPS can handle the inrush currents then what are we worried about? Is it the THD? Would be great if someone can help understand.
Is a good double conversion UPS with unity power factor(something like the eaton 9px) still not good enough for high current amplifiers? If the UPS can handle the inrush currents then what are we worried about? Is it the THD? Would be great if someone can help understand.