Greenwave 2500i AC Filter Review

[MediumRare]

@amirm Starting with an instrument grade DAC is perhaps unfair - asking to improve on perfection. How about using a device with plenty of room for improvement, maybe even one with a questionable power supply. A Pass amp comes to mind.

 

[NwAvGuy]

If you don't have an issue it's not going to solve a problem. In my situation I was getting a FM signal in my line from a neighbor and this product fixed it for like $30.

 

[amirm]

@amirm Starting with an instrument grade DAC is perhaps unfair - asking to improve on perfection. How about using a device with plenty of room for improvement, maybe even one with a questionable power supply. A Pass amp comes to mind.

I don't have a Pass Amp. If a device needs this cheap AC filter to sound right, it is time to get something else.

 

[kemmler3D]

Someone should report these clowns to the FDA for making health claims based on absolutely nothing, that's pretty illegal.

I also move that if any more reviews of AC filters are to be conducted, the manufacturer submit some measurements showing theoretical audible changes first. They're pretty much a scam even just starting from the basic concept, so at this point I feel like more reviews of AC products will lend more legitimacy to the category than it deserves. It sort of implies that someday one of them might actually work... which is surely possible in theory but in practice I have my doubts...

 

[amirm]

Amazing reviews on Amazon:

'Excellent, works as advertised. Noticed significant change in feel to the house. Tested and confirmed reduced enforcement with emf meter."

"Great product. Noticed a reduction in our electric bill. Not sure if that is a happy byproduct, or if that is just a coincidence. I will be ordering more."

They have large packages of these. Above quotes were from 16 filter pack for $509!!!

 

[DonR]

Shame about the marketing blurb as $35 is reasonable for a working HF filter. If you had a piece of equipment that had issues with 20K-100K content on your power line AND you did not want to replace said equipment with something that actually worked properly, then it would serve a purpose.

 

[JktHifi]

this kind of device can be found for less than $10.
Power conditioner/ac filter is real.
Usually found on power strip (3 or more branches) along with surge protector inside.

 

[Beave]

While not particularly helpful for audio, I wouldn't jump to conclusions about health so quickly. EMI actually is harmful, and electronics should be designed to reduce it's emission/transmission as much as possible. Here's an article from Cadence on EMI and its relation to PCB design:

EMI and Safety: Hazards, Risks, and Designing to Avoid Them

Understand the impact of EMI on circuit reliability and critical safety applications.

resources.pcb.cadence.com

In the article many of the tests for compliance indicate a range starting from as low a frequency as 150khz. This filter does seem to eliminate a spike around 700khz (at least that's what it looks like in the graph, but please correct me if I'm wrong Amir), and another one right around 150khz which both fall within the range of some of these tests. I'm not qualified to say whether or not such a device can improve health, but as Amir showed, this device did also result in another reduced high frequency spike (albeit out of the range of tested frequencies from the article) that did still make its way into the output of a well filtered device. The level is already so low that it's completely inconsequential for anything really, but remember this is, as Amir has already stated, a device that already has good filtering. This has demonstrated that it is possible for HF noise to make it to a device's output, and even one that is well filtered, so using this product on a a high powered device/appliance that has poor or no filtration at all might actually make sense. I emphasize that I say MIGHT. Again, I'm not qualified to say with certainty whether or not this device actually is beneficial for health, or if it makes sense to buy them, but it at least does make a measurable difference at frequencies that fall within the range of testing for EMI compliance... I do personally find the claims a bit hysterical, and doubt whether the device's effects are of any consequence to health, but the testing does indicate that it is doing somethign for its INTENDED purpose.

What does your linked article have to do with your claim that EMI is harmful?

 

[Beave]

They sell a "Low EMF Corded Landline Phone" and an "EMF Shielding Device for Cell Phones."

If the EMF Shielding device for cell phones works, then your cell phone doesn't, right?

 

[kencreten]

I cannot believe that this ... power conditioning product is so horrible.... ...... .........

 

[BoredErica]

Is testing of DC Offset Blockers like ifi Silentpower possible? It helped reduce the buzz from my Rythmik f12 a lot. Wonder which ones are more effective than others. Maybe it can be measured electrically rather than w/ SPL meter.

 

[wwenze]

Is testing of DC Offset Blockers like ifi Silentpower possible? It helped reduce the buzz from my Rythmik f12 a lot. Wonder which ones are more effective than others. Maybe it can be measured electrically rather than w/ SPL meter.

What do you want to measure?

Some suggestion:

- Maximum DC voltage it can block
- Maximum current before exploding
- Impact on AC waveform and consequently impact on connected equipment
- Impedance
- Power factor

 

[MediumRare]

I don't have a Pass Amp. If a device needs this cheap AC filter to sound right, it is time to get something else.

I don’t disagree with your overall recommendation, but I do disagree with your comment. This item is supposed to solve a problem. You are claiming to test if it does that. You have not. You’ve given it an impossible situation in which it is guaranteed to fail. Since it actually does something, unlike a $10k USB cable, the credibility of this site depends on you giving devices under review a fair chance to succeed or fail in a suitable use case. I urge you to reconsider.

 

[Shadow12347]

What does your linked article have to do with your claim that EMI is harmful?

Let me answer your question with another question. Why does EMI Emissions Compliance exist?

 

[SuicideSquid]

Let me answer your question with another question. Why does EMI Emissions Compliance exist?

To prevent a poorly-engineered device from screwing up a nearby properly-engineered device.

@amirm Starting with an instrument grade DAC is perhaps unfair - asking to improve on perfection. How about using a device with plenty of room for improvement, maybe even one with a questionable power supply. A Pass amp comes to mind.

This seems to me to be backwards - a mediocre DAC would hide any theoretical power line noise behind its already-high noise floor. A highly-revealing SOA DAC that has very little self-noise should give you the highest chance of measuring noise being introduced from other sources, such as power lines.

 

[Shadow12347]

To prevent a poorly-engineered device from screwing up a nearby properly-engineered device.

Correct. The other half of it is due to potential health concerns:

Electromagnetic field induced biological effects in humans - PubMed

Exposure to artificial radio frequency electromagnetic fields (EMFs) has increased significantly in recent decades. Therefore, there is a growing scientific and social interest in its influence on health, even upon exposure significantly below the applicable standards. The intensity of...

pubmed.ncbi.nlm.nih.gov

Electromagnetic field and brain development - PubMed

Rapid advances in technology involve increased exposures to radio-frequency/microwave radiation from mobile phones and other wireless transmitting devices. As cell phones are held close to the head during talking and often stored next to the reproductive organs, studies are mostly focused on the...

pubmed.ncbi.nlm.nih.gov

Threshold of radiofrequency electromagnetic field effect on human brain - PubMed

The analyses of the physical model of nonthermal mechanisms of RF EMF effect leads to conclusion that no principal threshold of the effect can be determined. According to the review of experimental data, the rate of detected RF EMF effects is 76.7% in resting EEG studies, 41.7% in sleep EEG and...

pubmed.ncbi.nlm.nih.gov

https://www.researchgate.net/publication/348563155_EFFECTS_OF_ELECTROMAGNETIC_FIELD_ON_HUMAN_BODY

But the purpose of the article I sent was more to point out that the frequencies that are attenuated by this device do fall within the range used for testing for compliance. Whether or not those frequencies or the level at which they are at do affect health, I cannot say. I am not defending the device, nor am I saying that it would be beneficial to health, but it does technically reduce (at least transmitted) EMI.

 

[SuicideSquid]

Correct. The other half of it is due to potential health concerns:

Electromagnetic field induced biological effects in humans - PubMed

Exposure to artificial radio frequency electromagnetic fields (EMFs) has increased significantly in recent decades. Therefore, there is a growing scientific and social interest in its influence on health, even upon exposure significantly below the applicable standards. The intensity of...

pubmed.ncbi.nlm.nih.gov

Electromagnetic field and brain development - PubMed

Rapid advances in technology involve increased exposures to radio-frequency/microwave radiation from mobile phones and other wireless transmitting devices. As cell phones are held close to the head during talking and often stored next to the reproductive organs, studies are mostly focused on the...

pubmed.ncbi.nlm.nih.gov

Threshold of radiofrequency electromagnetic field effect on human brain - PubMed

The analyses of the physical model of nonthermal mechanisms of RF EMF effect leads to conclusion that no principal threshold of the effect can be determined. According to the review of experimental data, the rate of detected RF EMF effects is 76.7% in resting EEG studies, 41.7% in sleep EEG and...

pubmed.ncbi.nlm.nih.gov

https://www.researchgate.net/publication/348563155_EFFECTS_OF_ELECTROMAGNETIC_FIELD_ON_HUMAN_BODY

There remains no good evidence (links to pubmed entries from random Polish journals on small studies showing results that do not replicate is not good evidence) that exposure to non-ionising radiation is harmful to humans except at levels that cause tissue heating (which are levels of EMF far beyond what even a non-compliant home devices would never come close to approaching - we're talking kilowatts of EMF output - the inside of a microwave, or a few foot radius around a commercial radar device, for example).

The completely baseless assertion that these filtering devices will somehow protect you from scary harmful EMF is delusional snake oil of the highest level.

 

[fpitas]

@amirm Starting with an instrument grade DAC is perhaps unfair - asking to improve on perfection. How about using a device with plenty of room for improvement, maybe even one with a questionable power supply. A Pass amp comes to mind.

My experience with his amps (I own one) is that the supply is fine. What have you seen?

 

[DonR]

Let me answer your question with another question. Why does EMI Emissions Compliance exist?

Any HF on power lines is likely to be very small and thus, if passed through, will likely produce insignificant radiation. It is more about how received HF affects circuits which, if designed correctly, should not be affected at all.

 

[fpitas]

Let me answer your question with another question. Why does EMI Emissions Compliance exist?

I used to perform those measurements for a living. Trust me, they have nothing to do with human health.