Studies On Residential Power Line Noise Part 11 - Noise Harvester and Quietline
PS Audio's Noise Harvester and Audioprism's Quietline are claimed to reduce the noise induced on mains power lines by electromagnetic interference and radio frequency interference. PS Audio does not publish specifications for the Noise Harvester. I found out that the Harvester operated in the 7 kHz to 15 kHz frequency range by searching the PS Audio Internet forum. Audioprism's published specification for the Quietline says it "operates from the middle of the audio band to several hundred megahertz".
The Noise Harvester is claimed to work by gathering and storing noise energy in a capacitor, which is then bled off by an LED. Therefore, electrical noise energy is converted to light. The faster the Noise Harvester's LED blinks, the greater the amount of noise that is being converted to light. It is priced at $99.95.
The Quietline is claimed to work by shunting noise energy from line to neutral. It is priced at $29.99.
Figure 1. Audioprism's Quietline and PS Audio Noise Harvester power line noise filters.
Figure 2. Single Noise Harvester plugged into kitchen counter receptacle.
Figure 3. Two Noise Harvesters plugged into kitchen counter receptacle.
Figure 4. Noise Harvester and Quietline plugged into kitchen counter receptacle.
The Fast Fourier Transform function of a Tektronix TDS 2012 did not show any changes in the powerline's noise spectrum with either the Noise Harvester or the Quietline plugged in. This was expected since the Harvester and Quietline operate far above the 60 Hz power line frequency. PS Audio claims that the more Noise Harvesters are used on an AC circuit, the more noise will be removed. The results from using one to four Noise Harvesters in two of my kitchen counter receptacles (two outlets per receptacle) on three different days are shown in table 1. My home is wired so that lights and receptacles are on different circuits. There are four receptacles on this particular AC circuit: three above the kitchen counter and one below the counter which serves the disposal. Nothing else was plugged into the receptacles other than the disposal, Harvesters and Quietline.
Blinks were counted for 1 minute and trials were timed with a digital topwatch. Each trial scenario was repeated five times over a 45 minute period on each day. There were differences in the amount of blinks recorded on different days, but the number of blinks recorded on successive trial scenarios during a 45 minute period on the same day were constant.
I expected to see the blinking rate decrease with each successive Noise Harvester plugged in. However, there was only a decrease in the blinking rate when going from one Harvester to two. Going from two to three or three to four Harvesters produced no further reduction in blink rate.
When a Quietline was plugged into the same receptacle as a Noise Harvester, the Harvester's blink rate increased.
Two Channel Audio System Listening Evaluations
Two musical selections were used for all listening trials:
A musical selection of average recording quality (clarity, detail, spatiality, dynamics): Track twelve ("When We Come Together") from Jakiem Joyner's "Lil Man Soul" CD. Specific "markers" that I use to judge sound quality as rendered on different equipment are the electric guitar crack at the very beginning, the high hat strike at 00:06, a low pitched scraping sound at 00:24, a high pitched scraping sound at 00:59, and the electric guitar notes at the right of the sound stage beginning at 04:24.
A musical selection of excellent recording quality (clarity, detail, spatiality, dynamics): Track two ("Lisa") from Stanley Clarke's "At the Movies" CD . It has a growling electric bass at the intro, sharp drum rim shots throughout, well recorded electric lead guitar transient notes, and airy background vocals, although it is primarily an instrumental song.
Listening evaluations were done with two different preamplifiers: a Pass Labs X0.2 and its next generation, and higher resolution, successor, the XP-30.
My two channel system is fed by three dedicated 20 amp AC circuits, which are terminated by PS Audio Soloist Premier SE in-wall passive power conditioners. Each monoblock power amp is on a separate circuit. The third circuit feeds a PS Audio P10 AC regenerator, which feeds the source components and line level and phono preamplifiers. A Noise Harvester or a Quietline was plugged into the upper outlet of each Soloist receptacle during specific trials.
Noise Harvester Trials With The X0.2 Preamp
Music sounded louder and clearer. I could stand next to the left speaker and hear the change in clarity of the drum rim shots as I plugged in and unplugged the Harvester from the receptacle feeding the left monoblock power amp. There was a little more fluidity and articulation in the electric bass notes.
Quietline Trials With The X0.2 Preamp
Music sounded louder and clearer than with the Harvesters. I could stand next to the left speaker and hear the change in clarity of the drum rim shots as I plugged in and unplugged the Quietline from the receptacle feeding the left monoblock power amp. The reverberent echos (in the left channel) of sounds in the right channel were easier to hear. There was also a small increase in tactile sensation, as felt through my armrests, that was not there with the Harvesters.
Noise Harvester and Quietline Trials With The XP-30 Preamp
The level of clarity and detail of the XP-30 without either the Harvesters or the Quietlines was greater than the clarity and detail of the X0.2 with the Harvesters and Quietlines. When the Harvesters were plugged in, I did not perceive a difference in clarity or detail, but there was a small increase in apparent loudness, which indicated a lowering of the noise floor. With the Quietlines plugged in, there was a greater increase in apparent loudness over the Harvesters. Pass Labs claims that the XP-30 has significantly better EMI shielding than the X0.2. Compared to the X0.2, it appeared that the XP-30 was not as sensitive to the types of noise that the Harvester and Quietline filter out.
The rate of Noise Harvester blinking was 600 blinks per minute at the left monoblock's AC receptacle, 150 blinks per minute at the right monoblock's AC receptacle, and 58 blinks per minute at the P10 AC regenerator's AC receptacle.
Home Theater Audio And Video Trials
My home theater system has high video resolution and moderate audio resolution.
I did not perceive any visual performance improvement from using either the Noise Harvesters or Quietlines on the two dedicated 20 amp AC circuits that feed the home theater system. Both AC circuits are terminated by a PS Audio Soloist Premier SE in-wall passive power conditioner. The video equipment is fed by a PS Audio P5 AC regenerator. Test patterns and the "Quantum of Solace" Blu-ray were used for video evaluations.
Both the Noise Harvester and Quietline caused an increase in apparent sound level and an increase in clarity and detail. For example, the MGM lion's roar prior to the start of "Quantum of Solace" was louder, heavier, more growly and more detailed with the Harvester and more so with the Quietline. The two CD's used in the two channel evaluation, as well as the "Quantum of Solace" Blu-ray, were used in the home theater audio evaluation. The audio equipment is fed by a PS Audio P10 AC regenerator.
Video evaluation was done at the viewing location and by comparing pixel level screen shots using the method shown in figures 6, 7, and 8 of this thread.
The rate of Noise Harvester blinking was 106 blinks per minute at the P5 AC regenerator's AC receptacle and 600 blinks per minute at the P10 AC regenerator's AC receptacle.
Figure 5. Quietlines plugged into two of three dedicated 20 amp AC circuits feeding my two channel audio
The Quietlines provided higher performance at one-third the cost of the Harvesters in my two channel audio and home theater systems. The Quietlines were retained and the Noise Harvesters were sent back. With a better EMI-shielded preamp (the XP-30 compared to the X0.2) in a high resolution two channel audio system, neither the Noise Harvester nor the Quietline provided an improvement in clarity and detail. Each of them did lower the noise floor which resulted in an apparent increase in sound level. Neither the Quietline nor the Harvester improved video performance in the home theater system, although small improvements in clarity, detail and the weight of sound were realized.
I expect that better results with the Harvesters may be realized in cases where several of them can be used on multiple receptacles on the same AC circuit. Of course, that is not an option with a dedicated circuit with only a single receptacle. The multiple unit performance advantage may also be true of the Quietlines.
Another fine investigation!!!
Thank you for this and your previous power line investigations. I happened on your P5/P10 articles while I was waiting for a P10 to arrive. Your article gave some great info on what to expect and how to best optimize the beast including fuse upgrades and helped me get it running well without a lot of trial and error.
I've been experimenting a bit with noise reduction filter in my system too, not only in parallel with my AC inputs, but also on AC circuits outside of the system's (sadly, I don't have dedicated lines in this house yet... I did them awhile back in a previous house and was VERY impressed with the improvements).
I've done three different types of filtering. First were filter chokes in parallel with the AC circuits. I used these before getting the P10 and was surprised that I preferred the P10 with them plugged into the same AC outlet as the P10. I'm using Hammond 193L and 193M chokes, as suggested in a number of threads on the Audio Asylum a few years back. I'm currently using one of each across the AC at the P10 outlet. The difference is a subtle lowering of the noise floor... the times I've left them unplugged by accident, after a short while listening, I think something is broken in my system until I plug them in again.
The second was to add ferrite clamps on power cords of appliances and other equipment that have SMPS's... microwave, washer, dryer, DVD players, TVs, all the extension cords where phone / tablet / PC power supplies or chargers are plugged in, etc. I don't think I could hear the difference adding any one of these clamps. But all of them together made a very noticable and significant noise-floor lowering. I started with what few clamps I had in my boxes from when people first tried them (and I never liked them on the power cords of any of my equipment), added some of the overpriced ones from Radio Shack, then ordered a bunch from Digikey. I did most of these long before I got the P10, but recently replaced my very old microwave (which had a linear supply!) with a new one (which probably doesn't) AND added a 2nd DVD player (with an SMPS) to the TV where my wife watches movies. After a few weeks, I realized that I never put a ferrite clamp on that player' cord... and when I did that I also added another couple to the microwave. These were surprisingly noticable in the system, with the highs gaining another level of sweetness.
The third are a couple of parallel filters, the somewhat pricer ones from Bruce Brisson's DIY Audio Kits. I added the first a few months back on the same circuit as my P10 and most of my system... nice improvement of lowering noise, making the highs sweeter, and focusing and fleshing out the mids. After a couple of months to make sure it was broken and settled in I got a 2nd... and after a week of it on the same AC circuit, I found the system had become 'confused' and less focused. Pulling it out returned the sound to how I remembered... and then putting it on another circuit in the house, the one for the bathrooms and their GFI circuits, brought the same type of improvements as the first, with a larger improvement in the mids than before.
My lessons from all of this was that while the P10 made a HUGE difference in the sonics of my system and improved the sound quality above even the best I had before, it does not eliminate the sonic impacts of problems on the AC lines upstream for me. I still hear some variation between 'good' powerline times (weekends, late evenings) and 'poor' powerline times (days, late-afternoons-early evenings). While it's better during the 'poor' times than the best before, it still varies. Adding other conditioning upstream can still make significant differences, especially if applied at the source of the problem (i.e. chokes on the cords of noise-producing appliances and equipment).
Also, I do have both an un-filtered and a filtered (PS Audio Soloist) set of outlets that I can plug the P10 into. I prefer the unfiltered, which gives me greater dynamics and bass power with only a tiny increase in noise.
All of this is a long-winded way to say try some of those filters on other circuits in your home along with ferrite chokes on the 'noisy' equipement... this worked well for me.
And I'm getting some of the Quietlines to try!
Greg in Mississippi
P.S. This system of mine is both complex and simple. Complex in that the program source is a computer music player based on the cMP/cPlay formula. I've taken it to the extreme with 9 linear supplies powering the computer, sound card, add-on DAC (and it's clock circuit), and a separate set of 3 linear supplies feeding the 'dirty' circuits, the processor, screen, SSD, and keyboard. The 'dirty' supplies are not powered through the P10 ,but go to a separate AC circuit and have their own set of choke filters on the AC input.
This music player has 'extreme' operating system reductions to where the Windows XP-based opsys and player take up only about 15Mb! This somewhat complex front-end feeds into a very simple, but high-quality shunt-stepped attenuator and a pair of Hypex NCore amps. These drive a pair of Eminent Technology LFT-IV planar speaker with upgraded crossovers.