This is a review and detailed measurements of the ZeroSurge 2R15W AC filter & surge protector. It is on kind loan from a member and costs US $239.
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I like the descriptive model name: it has two (2) outlets and is rated for 15 amps. A hefty AC cord gives one confidence that it can carry that much current.
If you are not familiar with the company and this product, their products (and that of another competitor) use "series" non-destructive surge protection devices. Traditional surge protectors rely on components that are in parallel with the line and sacrifice themselves should a sufficiently powerful surge arrives. Some can fail this way with catastrophic results (think smoke and fire). They are cheap and have the advantage of having no impact (if well designed) on power delivery of the unit. Series protection devices like the one in this review, shunt the power instead and are able to do so repeatedly. But by putting a circuit (inductor) in series, they are said to impact power delivery. They also cost a lot more as you can tell here.
I can't test the surge protection of these devices but can see if a) they improve the fidelity of audio system and b) whether they have a negative impact on power delivery. Many audiophiles buy these for reason (a) and to sleep easy should a surge arrive.
ZeroSurge Filtering Measurements
For such a device in theory having a benefit, it needs to filter noise in the audio band so let's test that. I first measure the "raw" AC coming out of my equipment rack power strip using a 1/100 attenuator:
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The level of distortion and noise remains more or less the same. Lots of harmonic distortion is responsible for creating 2.2% distortion added to the 60 Hz mains. Now let's do the same measurement but routing the AC through 2R15W:
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Focusing on THD+N, we see the same 2.2% so nothing has been filtered there. The sine wave on the left looks distorted just as it did when we didn't use the device. The FFT spectrum also appears to be the same but let's run a dedicated test to be sure:
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There doesn't seem to be any attenuation there. Based on this we can predict that performance of our audio gear won't be improved but let's test that theory.
EDIT: question was raised about the above measurements as to impact of loading down the ZeroSurge to see if it makes a difference in filtering. Before doing that, I expanded the measurement bandwidth 50 times to 1 MHz to see if there is a filter operating above audio band and there is:
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As is typical, filtering doesn't start until well above audio band around 40 kHz. Even then the attenuation is about 11 dB or so and not enough to shunt all that noise down.
I then tested the impact of having a load in the form of Hypex NCx500 amplifier plugged into the ZeroSurge:
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There seems to be some incremental attenuation around 20 to 50 kHz. The load is forming a network with the internal filter changing its transfer function. But the impact is again very minimal. The bulk of what is 'bad' remains with AC power.
ZeroSurge 2R15W Amplifier Measurement
I recently tested the new NCx500 high power class D from Hypex
so I thought it would make a good target for measuring the fidelity and impact on power of the amplifier. Let's start with our standard 4 ohm power sweep (with buffer enabled in NCx500):
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The raw AC (green) and run through ZeroSurge show identical noise and distortion. The two graphs are completely on top of each other indicating that no improvement to be had. You can take to the ban that the fidelity is the same.
But let's see if we lost some power starting with maximum power available into 4 ohm:
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There is a tiny impact here which is not even worth noting. Let's test burst power:
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Once again, the impact is tiny which could just be the extra wiring and outlet involved in the circuit. This is great news as it dispels the worry that you can't use these surge protectors for power amplifiers. Granted, we are talking almost 700 watts here and not 1,500 but still, you are unlikely to be pulling 600 watts continuously as I am doing here.
As with all the other power tweaks, filters and cables, no fidelity improvement is to be had with 2R15W. It doesn't "clean" the AC in any way that I can measure. And as a result, real-life testing with an amplifier shows the same performance with and without. On the other hand, it is a major sigh of relief that despite pulling some 700+ watts out of the box, it had essentially no impact on the amplifier performance.
Where this leaves us is that if you like its flavor of surge protection, you can proceed to use it for that purpose and not worry about power loss.
I can't recommend the ZeroSurge 2R15W as a fidelity improvement device. As a surge protector, going by what they say it does, it seems like a better bet than many cheap solutions.
As always, questions, comments, recommendations, etc. are welcome.
are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/