Review: PS Audio PS Audio Duet AC filter

Category: Accessories

For any in depth facts and figures, I point you towards the PS Audio web site, or the PS Audio dealership nearest you. I neither was provided any special offer, deal or proposition from the maker of the Duet to provide this info/review.

I paid for mine, just like anyone else would. Cash. Dead presidents. Duckets.

I did take advantage of the initial advance purchase to save some money by so doing. Apart from that I get nada. Zip. Zilch. …just that warm and fuzzy thing from trying to help other curious audio nuts.

It would seem that I have been quite the advocate for the passive line filters offered by PS Audio in the past. That is of course, once I got convinced some improvement to the sound could be had by using them… or any line filter for that matter. I previously just did not believe anything other than active conditioners could prove beneficial. I felt also active conditioners would impact the bandwidth and overall sound too. In respect to the impacting of the sound via conditioning devices, I was wrong. The passive ones I have tried from shunyata, and PS Audio have done nothing but aid my system in unearthing the sound it is capable of portraying. Although some degree of change was revealed in relation to the sound, I found the change both better served the music and for the most part a benign influence upon it.

Having bought a UPC 200 RIGHT AFTER THE RE-TOOLING/UPDATE which came out two years ago, in the fall of 2005, the idea PSA had something better in the works only a year later gave me both interest, and a touch of remorse. Such is the way of electronics. Best thing since sliced bread one day, and soon after? It’s just a memory with the onset of continued technological advances. Of course that intimates a whole re-thinking process, and an ongoing commitment to provide the best available technology to the consumer. PSA sure seems to be on that road.

The UPC 200 as I previously reviewed it herre at Audiogone was a superb addition to my then system. Mainly applied to the amplifier it allowed for a greater warmth and blackness in the background. I heard less of what I was not hearing in terms of line grunge and artifacts. It provided a more liquid, tapestry without encroachment on the fundamentals of the music, or it’s original ambient retrieval. Believe me, a most pleasant thing to be sure. (see my UPC 200 review for more details).

The Duet (s) take a different approach than did the 200. It’s a good tact and allows for nearly as much velvety texture, though provides far greater range of dynamic contrasts. There is no switching on the Duet as was evident on the UPC 200, to afford integration of unlike components, like mixing digital with analog. That’s hardwired into the device already. There is now however, an on/off switch which I must say is an added plus. Sure beats pulling the supply cord out of the wall if you are going away for some time. Upon energizing the Duet, it will blink a few times and then remain a soft steady light.

Another plus to the Duets credit is the voltage sensing circuitry now added. The Duet will not only diminish greatly the AC line nasties by a noticeable margin, it will also tell you if a low or high voltage condition is occurring. A light integrated into the on/off switch just above the IEC connector will flash during those conditions. Slowly or quickly depending on which situation transpires. Slow for low voltage, fast for higher waves of voltage. If indeed the overage is significant, say with a surge, there is also now a circuit breaker which will disengage automatically by popping out of its holder. Resetting the ckt. Breaker is simple. Push it back into the holder. Neat. It is located next to the supply cord IEC connection.

Instead of being hard wired completely inside, the Duet is on a bus like apparatus. Bars, or rails if you prefer, are used to transmit voltage to both sets of 15 A NEMA outlets. I found the new Duet outlets quite the grippy little outlets. Better than on the UPC 200 in holding onto larger after market power cables.

The Duet also just makes sense. Ergonomic sense. The Duet allows for more versatility in its’ incorporation to a system and existing household power supplies. Still some maneuvering might well be needed, but it is more the versatile unit in terms of how you can locate it. The Duet’s shape is angular. Triangular. Allowing for setting it with its’ two rear surfaces meeting both a wall and floor, if you choose, with the supplied IEC cord. Going into an end now, rather than the same plane as the device power cables, which go into the face of the unit, 90 degrees off angle to the supply cord rather than on the same facing area. That’s just gotta be a help especially with stiff power cords being used. Of course, if you prefer, it is quite comfortable resting directly onto the narrow facet I call the back, which will have the NEMA outlets facing the ceiling.

Isolation for this filter is also something to investigate for yourself. Attention here will indeed be rewarded to anyone with due diligence.

My single kick on this new technological marvel is as usual , the run in period. Although some degree of improvement is noticed right off, the really good showing will come later. Much later. A few hundred hours later was the case for me and the two Duets I bought. In fact while I’m on that “kick” aspect of the Duets, I should mention in all fairness that as the units I received were of the first run, both of mine failed quite soon after I received them. One and then the other a few days later. The failure was likely a minor issue however, I never was given the “How come it did that?” info.

What happened was the indicator light began to blink on one. Steadily. Slowly. Incessantly. This action under proper operating circumstances indicates an under power situation. Wherein you would want to shut things down till proper voltages were available and thereby prevent any damages to the systems components. As both Duets were attached to my other PC/HT system, not hidden behind racks and gear, you couldn’t help but see it. The light is large. Trust me. If I can see it, anyone who has even limited vision can’t miss it.

Additionally, after a few days of being attached to the secondary system, I went about making some changes in the power cable array. I swapped one for another here and there and as I re-integrated it’s supply cord the Duet arced at it’s IEC connector. Briefly. Being somewhat stunned by that result I simply removed it from the system and made contact with Barrows Wormer at PSA.

Contacting PSA got me an RA number, some further info on the Duets operation, and a test of my own circuit integrity to make sure it was the device operating errantly, not my current supply. Just after the RA came via email, the other unit followed suit and began its slow blinking run. This one however did not arc or act dangerous in any way. It just kept indicating a situation that was found to be nonexistent. Eventually. Such cases on initial runs are regrettable, but do happen from time to time as the kinks get worked out.

PSA sent me two new ones even before I could get the bad ones returned to them. Barrows tested each to ensure proper operation prior to sending the second set to me. Now I got to say that is exceptional service, in my opinion. The two replacements have worked flawlessly ever since they arrived.

Once run in well enough the Duets handle music recreation in a “get out of the way” fashion. Though not as warmly set as the UPC 200 NEITHER is the bandwidth in any way, shape or form, veiled. By contrast, the Duet is noticeably the better in dynamics, extension, and honesty with regard to musical content. It shows no intrusion to the phase correlation of imbedded information either. In fact it does reveal such things easily and without attenuation or promotion. There is nothing the Duet introduces which is arbitrary or detracts from the listening experience. The music remains coherent, insightful, and true to form.

The background blackness coefficient rests in between the “dual mode” and “high current” modes of the UPC 200. it will not gloss over the sound with a velvety cloak as does the UPC 200 when set to HC, yet the Duet improves upon the conditions in the ‘DM’ configuration the UPC 200 allows. So the Duet is a ‘tweener’ in that blackness regard comparatively speaking.

In respect to another like product, the Shunyata Hydra 2, the Duet gives as much flow and air to the music as does the Hydra with a deeper hand at adding dark to the background. One note I made in comparing the Hydra 2 to the UPC 200 was the Hydra did in fact show some added filtering in both directions. Coming in line junk and outgoing as well. The Duet sounds as if that too is going on in the approached design. Unlike the Hydra 2, naturally, the Duet offers four NEMA outlets versus two..

One additional note and it pertains to preference and design, the technology incorporated in the build of the new line of ‘passives’ from PS, doesn’t change the metallurgy installed from model to model, as does some other manufacturers. The Shunyata Hydra 4 as example, uses silver as the bus transmission line within it unlike in it’s sibling Hydra 2, which keeps to the copper camp for power transmission, giving a bit more life or zip to the presentation than it’s seemingly warmer copper sibling, the Hydra 2. The Hydra Six uses still more. So Shunyata will afford via their cast on line filtering some other choices than simple line filtering advances.

PSA keeps to a more uniform approach. Instilling sameness there allows for some greater flexibility in changing filtration with system changes without the concerns of mismatching, and effects to the systems sonic presentation.

In other words, if you need more outlets later on down the road and already have say a PS Audio Duet, in place, replacing it is more the simple step than worrying about different metals being used which can affect the system sound and synergy as a by product of it’s integration.

Whatever color, extension, prominence, or issue you have now, if it’s not related to power line anomalies, you may still have it after putting the Duet into your system. I had nothing so major it appeared as intrusive or error ridden. I had no excessive or noticeable issues in areas like ground loop sibilance, or hums. I had at least, what anyone has in their incoming line power, a less than fine source to be sure. Therefore, I can not say the Duet is something of a ‘fix’ in that area.

You might ask, “Well, if there were no audible, or obvious line voltage issues going in, how did you see any benefit using the Duet?”


The sound. It improved. The unwanted dirty voltage was redressed. Dusted off. Vacuumed up a bit. In truth, ask PS Audio. I don’t know how it did what it did, and really I don’t care. I know it was better with the Duet (s0, in the system than out of it.

“Yeah? Well, how then?”

Press on pilgrim….

To its credit, I must say the Duet does add some degree of roundness to the music. I see it as improvement by subtraction, as I do many such devices. The most apparent gain is by revelation. I heard more of the music’s range, impact, and coherency. What once was a soft leading edge with the UPC 200 became better found, easier heard. Yet still not inscribed or etched as to induce shorter listening spells by added distractions. The sound was also set against a much richer darkened backdrop which set the sonic cues in better relief. One aspect I am quite sensitive to is the top end of the musical scale. The Duet’s scouring away much of the power line bugs, set that portion of the register more delineated and refined. Not quite to the sweet end of things, though surely an easier affair to listen to.

It mattered not if the recordings were studio or live, recent or quite old, the results were always the same. I found the Duet to be a key to unlocking another facet of my system. In all it added to the degree of pleasure I attained each and every time I sat down to dig some tunes. A greater ease to listening was also had as each of the instruments and artists were simpler to pick out.

One aspect of building a system that I have long dreaded due to previous poor experiences with overtly analytical and critical sounding systems, is gaining so much resolution and detail as to be subtractive from the experience. That will not happen by adding a Duet., or two, to a system. In fact it will help. Just don’t think of it or any other conditioning, oor filtering device as a patch for such issues. Look elsewhere for that remedy.

If you are looking to bust some line grunge, allow your system devices to breathe a bit easier, provide them some additional protection and possibly save yourself the expense of repurchase due to power line surges either way, and get closer to the actual sound of your system, then Duets might just be the ticket. Add in their cost and it seems a simple choice. I chose them as I like the notion of not redefining the power by active means. Still. Also as I have several dedicated circuits the Duets allowed me to take advantage of them more judiciously.

Given the build, technology, added circuitry precautions, performance levels, and the more than good support aspect, the PS Audio Duet is a real behind the scenes hero. One that gains a system greater insight to the affair of recreating the original musical envelope, and its emotional content. Adding in the price of admission, it’s a bonafide and easy recommendation for any system, one that should be on everyone’s short list of passive line filters to seek out and try in your rig.

If you are overwhelmed with accessories and equipment, and in need of more than the four outlets the Duet afford, step up to the Quintet which has five duplex NEMA outlets and additional interfaces yet remains a passive filtering agent like it’s smaller siblijng the Duet.

Still hungry? The Quintessence is the next logical step up and incorporates even more features, filtering, and outlets. Personally I’d like to see those benefits trickle down into units which don’t require as many outlets… thereby giving still better performance to those whose needs for power aren’t as demonstrative.

Each of the PS Audio power line filters comes with a supply cord enclosed, so there is no need to rush right out and spend more money. Not right away, anyhow.

The need for attending to line voltage artifacts is evident in the oeverwhelming majority of homes across the country. Even if you are presently unaware of them lurking on your systems power structure as you hear no significant cues alerting you to them. Even with dedicated circuits and the best components simple attendance to this area and the smallish outlay here can be quite substantial to gaining yourself far better system performance, and enjoyment.

It did for me…. And that’s what it is all about, right? I highly recommend the Duet by PS Audio. Past that I even more strongly recommend at least something by someone be used to lessen the incursive nature of power line gremlins. You’ll hear less of what you ain’t hearing now…. And consequently, you’ll hear more of what you wanted to hear in the first place.

Associated gear
Thor TA 1000 MK II w/RCA NOS tubes
BAT VK5i w/Matsushita 6DJ8’s, Amperex PQ US 7308 white label w/emblem, telefunken ECC188, & Tung sol 5881’s
Sony STVR 444 ES HT Receiver
BAT VK500 w/BAT pk.
Sony SCD xa 777 es CD Player
VSA VR4-JR (cherry)
Phase Tech PC 10.5 3 way towers
Phase Tech PC 6.5 2 way floor standing monitors
M.I.T. Magnum 3 III RCA 1.5m (source IC)
Nordost Blue Heaven 2m (source IC)
Monster M1000 (source IC)
Wireworld Polaris 5 RCA
Synergistic Resolution Ref X2 Active 1m XLR (MAIN ic)
Synergistic Signature 10 X2 Active bi wires (shotgun to top of JR)
Synergistic Alpha Quadd series X Active on JR bass driver only.
Elrod Signature 3 20A 6ft.
Shunyata Python helix VX 6ft. 15A (CD)
Shunyata Taipan helix alpha 6ft. 15A
VooDoo Black Dragon II 6ft. 15A
VooDoo Gold Dragon III 6ft. 15A ((X2 for amp)
VooDoo tesla II 20a 5ft.
PS Audio UPC 200
PS Audio Duet (s)
Sony DVD/VCR combo player
Sony 400 Cd carosel
Sony S30 61” RP TV
HD cable boxes
Dell optiplex 620 Desktop
Dell Dimension 4600 Desktop

After market spikes for JR’s.
Herbies Audio Labs halo tube rings
Herbies Audio Labs Iso cups w/Ebony ball footers
Mother Nature wood footers (Mahogany, teak, Coco, and others)
Vibrapod #3
Vibrapod cones

All devices draw power via 4 dedicated 20A ckts. Using hosp. grd duplex outlets

Similar products
Transparent, chang light speed, PSA UPC 200

Thanks very much for sharing your perspective on this unit. I have two of them and can attest to the performance gain you mentioned.


Thank you.

Funny thing to me is always my reluctance to change. When I found the Duets to be at about 200 hours I plugged them into my system. Didn't care for the sound then. Put back in the UPC200. Better... IMO. It wasn't really, but I was more familiar with it. I left the second Duet on the PC STUFF for more run in, leaving the first to provide front end gear power and the 200 servicing the amp.

Recently I thought "Let's see now." and swapped out the 200 for the second Duet for amp driving duty. Well. That move was a decided plus. Far less restrictive sounding and an easier presentation. Although at the cost of some darkness to the backdrop... albeit marginal, the overall was appreciably better... and especially in the regions of bass extension and definition.

In fact, last night I heard more bass in my system than I had since the sub was in it. remarkable. I should also add that I just retubed the Thor TA 1000 MK II with NOS RCA throughout. I believe they also finally got on board as they passed the 40-50 hour run in mark.

All of that with the Elrod Sig III supplying the Duet + VK500. it was most impressive. IMO.

A word about the power switch on the PS Audio Duets.

I said the UPC 200 took some time to manifest it’s best filtration level. The same thing happens with the Duet, though the time frame is shorter and the results better. What does happen, eventually, is there continues a build up of ‘quieting’ that will peak in a few days. At it’s peak, and this will vary from system to system, the overall sound will retain it’s dynamic range and harmonic balance. Yet there is noticeably an added layer of warmth then inclusive to the sound.

If this is not to preference, it’s a simple matter to just press the power switch on the Duet so it goes off. The light will go out then. Simply turning it back on prior to the next listening session will then have ‘reset’ the Duet and it will begin it’s slow, marked climb to peak filtration. Every couple, three days works for me. Less if you wish to reduce or eliminate any added warmth to the sound.

Hitting the switch now and then to reset the Duet does beat pulling the plug and I’d recommend it if things are being left unattended for extended periods. I thought that an important point to pass along. Sorry I forgot initially.

...coming soon... What I think the Running springs Haley does for my system.
Fellow owners of PS Audio Duet (I just ordered one today) - I checked with Tech Support and also my amp maker (McIntosh), and they said that I can safely use one single Duet to plug in my 400W amp, my Bel Cantao Dac, and my CD player. Do you see any load problem / sound degradation with plugging all 3 components into one Duet? The amp is in one IsoZone, the Dac and the CD player in the other IsoZone, and I have one free socket left on the Duet. Thanks and Happy New Year! -Peng
No problem.

I used it with a BAT vk500, and twin Dodd Mono blocks, at various times. Also with a preamp plugged into it at the same time.

I no longer use Duets for power train components. Instead, I use a Running Springs Haley. I use Duets now for digital gear and in a secondary system for some HT components.

the only other consideration might be that of sound... and the supply cord feeding the Duet will play a significant role.
Thanks Blindjim! My biggest concern was possbile interference issues and load problems with my 3 components all plugged into one Duet (amp + dac + cd), but sounds like it would be just fine. I look forward to experience the Duet in my 2-ch system. I have a heavy-duty 12-amp cord which I may use with the Duet. -Peng
I currently have a Quintet and I have everything plugged into it. I have my W4S 3000W amp (Ihave 4ohm speakers), my Onkyo SR-806 receiver, my Samsung 50" Plasma, Sansung BR player, and my digital cable box all plugged in to one quintet. Do you think this is overloading the quintet? I am considering a duet to add just fpr the amp. Will this be beneficial, or a lateral move?


Sorry it took so long to get this down...

If everything was plugged into the same outlet/ckt before, it should all be fine now.

Whenever you can split the load off of a ckt to lessen the draw, your likely gonna notice some changes, even if marginal. I think that's what we're talking about here, marginality.

I suspect adding another filter, say a Duet, if on another ckt altogether from whatever else the system is using now, would be of more help.

Naturally, the bigger change will be the application of differing power cords supplying the filters. For instance, using a pc made more for digital or front end gear, or one made primarily for power trains.

that's how I've split up my system. Using one filter for digital stuff, another for power train gear (primarily but not exclusively sometimes), and yet another for my personal confuser & its accessories. I've another for the BR system.

All but the BR system are on separate dedicated power lines, all 20A too...

It's hard to tell which is best... filtration or dedicated lines. I think it's conditioning actually... but can only speak for my own circumstances. having done both, just ded lines, and ded lines with conditioning... and just conditioning. I prefer the conditioning as the better item to have as a rule if the choice comes down to which one to have. naturally ded lines help... just not as much as filtration.

it's easy enough to see too... just disconnect the cond/filter from the rig. Listen for a couple days... plug it back into the rig once more. Listen again.

You'll find out! RWV.

Lastly, there's this.... with a filter/cond that has ckt overload and under run protection, your gear is safer at any length. Protedcting your investment always seems a good move to me.

Been a while since anyone posted on this thread but if anyone's still following this...

I just got a Duet and am using it for my pre-amp and SACD player. It certainly makes things sound crisper, with vocals and instruments more defined. However, it seems to do so at the expense of a slight emphasis on the upper frequencies and a reduction in bass energy. Is this something I should expect will change over time or is this just part of what the Duet does to the sound?
Is the Shunyata Hydra 2 a better option if I don't like the emphasis on high frequencies that I get with the Duet? Or Running Springs Audio?
Camb, yes I'm experiencing the same thing and I don't care for it. I think the unit is fairly new so I'll run it another 100 hours and then determine whether it's a good fit with my equipment. Take care, Dave

camb .... italian..

I feel the anomoly you both are experiencing is apart from the Duet's character. It sounds more like a ground loop influence perhaps.... or the supply cord is not a good match.

I've experienced no such condition with either of two Duets. Either on Dedicated power lines or not. Not a wit of tipped up emphasis or too much treble energy.

The supply cord for the Duet or most conditioners is about as important to the final influence on the sound as is the filter itself.

The Hydra 2 as I recall has no such emphasis on upper band harmonics, but then none of the filters or conditioners I've experienced or owned have yielded such results.

Filters and/or conditioners do not remove ground loop issues. Neither can one expect an item like the Hydra 2, Duet, or likewise devices to quell, repair, remedy or fix every electical grunge, interference, or negative influence pre-existing at one's service box. Nor will they neutralize system mis matching or introduce synergy where none was before.

When brand new.... my Duets took several hundred hours of run in before they smoothed out entirely and voiced equally the full extent of the bandwidth.

Within a month of being on, any and all abhorent irregularities were extinguished.

One last thought here is these Duets might be in need of a good look see from PSA.

Again, try another supply cord, check out how the Satellite or cable boxes are arranged and no GL issues abound.

Good luck.