puratube V2 (2026) - ac noise reduction
High end AC line purification!
(Updated for 2026 with wider bandwidth - see below)
(Updated for 2026 with wider bandwidth - see below)
These filters are an evolution of many years of work. They are usually hidden at shows but at the Montreal audio Fest 2024 we didn't have a choice to expose them as we ran out of receptacles on the rear wall. I never thought that people would ask what those black cylinders were for but once they did I would demo the filter live using the EMI tester. The results were amazing as the Hotel room electricity had a lot of noise when measured with the tool. The average measured noise in this Hotel room was around 1600mV and once the filter was connected to the circuit it would fall to below 50mV. Note that the Pteros V2 power bar used at the show had filters inside (DC blocker, EMI and RFI). The addition of the Puratube worked in unison to lower the high level of EMI present. Good results can be achieved with multiple Puratubes as described further below.
The EMI tool used is not a laboratory grade unit but it can measure from 10KHz-10MHz and is an affordable alternative for consumers wanting to test their electrical environment that features a visual presentation & sound of AC line noise.
How to rate line noise with EMI tool?
Compared with the chart above the noise level was in the "Poor" region at the time of testing at the Hotel room. Some homes are quieter than others and the noise level depends on many factors such as time of day, shops that use motors, heat pumps, fridges, freezers, electric car chargers etc.. Even your neighbors use of electricity affects the line noise in your home. Unless you are alone on the transformer power line you are getting infected by the others that are connected to this power line. Knowing this our goal is to get to a "Very good <100mV" which is achievable with multiple units. That said any lowered levels of EMI is better than higher levels.
Some will say that the noise is above the audio band and thus should not affect the sound. True the noise is mostly above the audio band but the problem lies in the produced harmonics of this noise that finds its way on the audio signal. Lowering this noise is just beneficial with no draw backs like certain commercial filters that are in series with the load (CD player, preamplifier, amplifiers...). The Puratube filters are parallel units and as such cannot limit current and may contribute to some power factor correction.
The EMI tool used is not a laboratory grade unit but it can measure from 10KHz-10MHz and is an affordable alternative for consumers wanting to test their electrical environment that features a visual presentation & sound of AC line noise.
How to rate line noise with EMI tool?
- <50mV Excellent
- <100mV Very Good
- <800mV Good
- <1000mV Average
- >1500mV Poor
Compared with the chart above the noise level was in the "Poor" region at the time of testing at the Hotel room. Some homes are quieter than others and the noise level depends on many factors such as time of day, shops that use motors, heat pumps, fridges, freezers, electric car chargers etc.. Even your neighbors use of electricity affects the line noise in your home. Unless you are alone on the transformer power line you are getting infected by the others that are connected to this power line. Knowing this our goal is to get to a "Very good <100mV" which is achievable with multiple units. That said any lowered levels of EMI is better than higher levels.
Some will say that the noise is above the audio band and thus should not affect the sound. True the noise is mostly above the audio band but the problem lies in the produced harmonics of this noise that finds its way on the audio signal. Lowering this noise is just beneficial with no draw backs like certain commercial filters that are in series with the load (CD player, preamplifier, amplifiers...). The Puratube filters are parallel units and as such cannot limit current and may contribute to some power factor correction.
Testing filters with an EMI meter
From left to right:
- First photo: No Puratube - 672mV
- Second photo: Puratube added in same socket - 194mV
- Third photo: Puratube added near the breaker box - 119mV
- Fourth photo: Puratube added at audio system receptacle which is across the room - 92mV
Puratube V2
Description:
These Puratubes are effective in reducing AC line noise and include Enhanced Ground Tech. The Puratubes presented here are upgraded versions (see below for changes late 2025 model = V2 version) of what has been seen on various videos on Youtube. They provide a better low level presentation* and expanded sound stage* compared to the prototype model used at the Montreal 2024 Audio Fest. This is our best filter and is very effective in reducing noise / EMI in your AC electrical network and your living environment.
*Perceived performance gains are different from one system to the next and also the electrical noise that is present.
*Perceived performance gains are different from one system to the next and also the electrical noise that is present.
Specifications and features
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What to expect overall
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The perceived performance gains will vary from system to system / environment. The changes vary from " That made a difference" to "WOW that is just incredible". In all cases once experienced it is is hard to do without.
how many to purchase?
The amount of units added give better performance but with diminishing returns. Typical subjective listening tests results could be rated as follows for real world results: 1 unit 60%, 2 units 75%, 3 units 85% and so on. The subjective difference between adding units will differ from system to system / the amount of electrical noise present at any given time. The electrical noise varies during a 24 hour period and is different from household to household. The percentages above are used in a subjective manner and not a measured fact.
Price for 120V Volts AC:
1 X 285.00$ each
2 X 570.00$ - 15 = 555.00$
For 220-240V AC 300.00CAD each - contact us here or use the information below.
For sales or questions: [email protected] or 438-338-0218.
All prices do not include shipping/insurance/customs or sales tax if applicable.
Please take note that if these units are out of stock we ask for 14 days to turn around for delivery. Depending on our work load times may vary. We strive for the best service and will communicate transparently.
*Perceived performance gains are different from one system to the next.
Warranty - AC filters : 2 years (transferable) See warranty page for detailed information.
1 X 285.00$ each
2 X 570.00$ - 15 = 555.00$
For 220-240V AC 300.00CAD each - contact us here or use the information below.
For sales or questions: [email protected] or 438-338-0218.
All prices do not include shipping/insurance/customs or sales tax if applicable.
Please take note that if these units are out of stock we ask for 14 days to turn around for delivery. Depending on our work load times may vary. We strive for the best service and will communicate transparently.
*Perceived performance gains are different from one system to the next.
Warranty - AC filters : 2 years (transferable) See warranty page for detailed information.
How to use:
Always looking for the best repeatable performance these guidelines may / have changed. The good news is that the new units (Puratube V2) seem to perform so well that more than two maybe superfluous.
FAQ
I have a power bar / conditioner / isolation transformer.... what will happen if I add a Puratube?
If you have a power filter / conditioner / isolation transformer you may surprised once measured with the EMI tool that many such products actually add noise to your AC line which is very strange indeed as most advertise the contrary (measured with the EMI tool before the power bar / filter /conditioner and the output of these devices). By adding a Puratube before and after these conditioners shown to improve their performance immensely. You may want to try and bypass your beloved conditioner and use the Puratubes only. You could be impressed at the gains in sonic performance when the Puratubes alone are used. As they say your mileage may vary so test away.
Will this take care of hum or RFI (Radio Frequency Interference)?
No. You need to find where your hum is coming from. IS everything connected to the same receptacle? If not your hum could be coming from a ground loop because the system is not connected to the same receptacle.
For RFI you need to figure out if it is your cables or your equipment that is the problem. Try snap on chokes on your cables (interconnects, speaker cables and power cables) to see if this makes a difference. There are other solutions but get the advice of a technician. Try different cables and see if this makes a difference. If the cables don't make a difference you can try to short the input of the amplifier and see if the RFI is gone. If so you should get your equipment checked and probably have an RFI filter installed at the input of the amplifier.
How do I know if I have an RFI problem?
Usually you can hear radio stations or static like noise at the tweeter when no signal is being amplified. Even if you don't hear this at the tweeter we all suffer from some level of EMI noise on the AC lines. By reducing this noise audio qualities can emerge during listening sessions. The Puratube V2 allows these possibilities.
Will the Puratube reduce noise introduced by certain light dimmers?
Yes and no. I depends on the dimmer in question. If your results are not good enough after using a Puratube you will need to change / upgrade your dimmers to fix this problem.
There are also some LED strips that have very noisy switching power supplies. You should consider a better switching or linear supply for these LED strips to fix the noise problem introduced by these supplies.
Performance of the units
The units are broad banded EMI reducing devices. There are some situations where the units are not very effective at reducing certain EMI instances. Even though this is a fact, overall EMI reduction is achieved. These units work roughly between 20Khz-+10Mhz at varying attenuation in that spectrum.
What are we up against?
Many things in a home or outside your home could be causing EMI. Here is a list to help you narrow down some offenders.
A) Low–mid frequency hum / buzz (20–200 kHz)Typical of:
• switching power supplies
• LED bulbs
• laptop chargers
• variable-speed motors
• solar inverters
B) Mid–high frequency hiss / frying / static (200 kHz–5 MHz)Typical of:
• SMPS fast edges
• arcing contacts
• motor brushes
• dimmers
• VFDs (electronic motor controller)
C) High-frequency clicking/sparking sounds (5–10+ MHz)Typical of:
• appliance relay arcing
• fluorescent ballast spikes
• VFD overshoot
• bad wall-warts (those square power supplies that plug in the wall receptacle)
D) A mix of A, B and C. In most homes this is a reality.
As you can conclude this is a broad list but not exhaustive. There are factors outside your home such as the neighbors new led lighting or charging of electric vehicles. Try to reduce your in house EMI then take a look outside your home. Reducing could equate to changing light dimmers for less offensive units or offending wall warts etc. Doing your homework here will help in reducing the overall EMI in your home. Happy hunting!
I scuffed/scratched my Puratube!
If ever you scratch or scuff the outer shell you can use a hair dryer in the high heat settings (or heat gun on low) and warm up the damaged area to reduce the visual damage. This mostly makes them look like new again.
Warnings
- 1 Puratube 2026 : Install at the receptacle of the audio system or the power bar / conditioner. (Biggest gains)
- 2 Puratubes 2026: If you have a power bar eg: power bar connected to the wall receptacle and audio equipment connected to the power bar then install Puratube 2025 at the same wall receptacle as the power bar and one on the power bar.
FAQ
I have a power bar / conditioner / isolation transformer.... what will happen if I add a Puratube?
If you have a power filter / conditioner / isolation transformer you may surprised once measured with the EMI tool that many such products actually add noise to your AC line which is very strange indeed as most advertise the contrary (measured with the EMI tool before the power bar / filter /conditioner and the output of these devices). By adding a Puratube before and after these conditioners shown to improve their performance immensely. You may want to try and bypass your beloved conditioner and use the Puratubes only. You could be impressed at the gains in sonic performance when the Puratubes alone are used. As they say your mileage may vary so test away.
Will this take care of hum or RFI (Radio Frequency Interference)?
No. You need to find where your hum is coming from. IS everything connected to the same receptacle? If not your hum could be coming from a ground loop because the system is not connected to the same receptacle.
For RFI you need to figure out if it is your cables or your equipment that is the problem. Try snap on chokes on your cables (interconnects, speaker cables and power cables) to see if this makes a difference. There are other solutions but get the advice of a technician. Try different cables and see if this makes a difference. If the cables don't make a difference you can try to short the input of the amplifier and see if the RFI is gone. If so you should get your equipment checked and probably have an RFI filter installed at the input of the amplifier.
How do I know if I have an RFI problem?
Usually you can hear radio stations or static like noise at the tweeter when no signal is being amplified. Even if you don't hear this at the tweeter we all suffer from some level of EMI noise on the AC lines. By reducing this noise audio qualities can emerge during listening sessions. The Puratube V2 allows these possibilities.
Will the Puratube reduce noise introduced by certain light dimmers?
Yes and no. I depends on the dimmer in question. If your results are not good enough after using a Puratube you will need to change / upgrade your dimmers to fix this problem.
There are also some LED strips that have very noisy switching power supplies. You should consider a better switching or linear supply for these LED strips to fix the noise problem introduced by these supplies.
Performance of the units
The units are broad banded EMI reducing devices. There are some situations where the units are not very effective at reducing certain EMI instances. Even though this is a fact, overall EMI reduction is achieved. These units work roughly between 20Khz-+10Mhz at varying attenuation in that spectrum.
What are we up against?
Many things in a home or outside your home could be causing EMI. Here is a list to help you narrow down some offenders.
A) Low–mid frequency hum / buzz (20–200 kHz)Typical of:
• switching power supplies
• LED bulbs
• laptop chargers
• variable-speed motors
• solar inverters
B) Mid–high frequency hiss / frying / static (200 kHz–5 MHz)Typical of:
• SMPS fast edges
• arcing contacts
• motor brushes
• dimmers
• VFDs (electronic motor controller)
C) High-frequency clicking/sparking sounds (5–10+ MHz)Typical of:
• appliance relay arcing
• fluorescent ballast spikes
• VFD overshoot
• bad wall-warts (those square power supplies that plug in the wall receptacle)
D) A mix of A, B and C. In most homes this is a reality.
As you can conclude this is a broad list but not exhaustive. There are factors outside your home such as the neighbors new led lighting or charging of electric vehicles. Try to reduce your in house EMI then take a look outside your home. Reducing could equate to changing light dimmers for less offensive units or offending wall warts etc. Doing your homework here will help in reducing the overall EMI in your home. Happy hunting!
I scuffed/scratched my Puratube!
If ever you scratch or scuff the outer shell you can use a hair dryer in the high heat settings (or heat gun on low) and warm up the damaged area to reduce the visual damage. This mostly makes them look like new again.
Warnings
- Do not plug into higher voltages then the recommended: 120AC 50/60Hz receptacles only (see 220-240 VAC version for higher voltages)
- Be careful to not touch the the connectors for a few seconds (3 seconds or so) when disconnecting from the wall as there may be residual voltage and a shock is possible
- A precaution of shorting out the prongs (the two flat ones) before touching is recommended
- For indoor use only
- These Puratube 2025 units will resist most AC line transients but there are limits such as lightning strikes or high voltage spikes and as such the units may fail and need replacing. None the less these units are made with the best components available and are very robust. See warranty page for further information.
- As a general safety precaution verification of proper receptacle wiring should be confirmed with a tool similar to the one below that is available at most hardware stores.
An example of an outlet circuit analyzer (Gardner Bender GFI-3501).
That said, enjoy this great product!
More tests using an oscilloscope and audio analyser
Here are oscilloscope screen shots at different bandwidths without a Puratube and with a Puratube plugged into the AC line. The pictures below are read in a vertical fashion.
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#1 Without Puratube
#1 With Puratube
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#2 Without Puratube
#2 With Puratube
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In these before and after shots we are using just one Puratube filter on the same receptacle that the scope is connected to. As demonstrated by these measurements the noise is significantly reduced.
Amplifier output test results using an audio analyzer
The tests above are nice but..... does it affect the output of audio equipment?
Amplifier output test results using an audio analyzer
The tests above are nice but..... does it affect the output of audio equipment?
- Below we can analyze the results of testing noise at the speaker output of an amplifier and plugging the Puratube V2 on the same 120v receptacle as the amplifier. The before and after picture show better SNR / lower noise than without a Puratube V2. The chosen frequencies are random and analyzing the two pictures we can conclude that a broad banded noise reduction is observed at the amplifier speaker output terminals. Markers 0-3 from the analyzer screen shots and the differences in lower noise in the following bullet list.
- 0. 4.019 kHz ~2 dB lower
- 1. 6.000 kHz is ~3 dB lower
- 2. 7.980 kHz is ~6dB lower
- 3. 2.821 kHz is ~6dB lower
- 3dB lower is 50% less (1:2 ratio = 50% or half)
- 6dB lower is 75% less (1:4 ratio = 25% or 1/4 of the original signal = 75% less)
Without Puratube V2
With Puratube V2 on same receptacle as amplifier. The noise levels went down on all 4 randomly chosen frequencies (0,1,2 and 3). The green vertical lines are the before measurement used as a visual reference and yellow are the actual measurement.
