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Acoustic Revive RTP-4ultimate Power Conditioner and Power Reference Power Cable Review

Ryan Coleman continues exploration of the Acoustic Revive technologies in its $2,250 RTP-4ultimate AC Conditioner and $600/1.5m Power Reference AC Cable

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If there were one tweak that an audiophile could use to educate non-audiophiles on why we labor so much for sound, power conditioning would be at the top of my list.

Whereas cables & vibration control accessories are often subtle in their effect, power conditioning can be as obvious as a yawn in church. Even in my system, which uses four dedicated 20-ampere lines with high-end wire & AC outlets, adding my current reference conditioner realized a dramatic improvement, resulting in a much lower noise floor, better detail & separation between notes, deeper bass, and a more organic flow to the music. Even my 60-year-old mother could hear the difference in my system. I’ve yet to encounter a system that didn’t benefit from power conditioning, and audiophiles should consider AC conditioning an indispensible addition to a high-end system.

Despite the myriad of power conditioning products available to audiophiles, all of them fall into one of two camps: active, or passive. The former involve the use of isolation transformers to reduce AC noise, which require their own AC source to operate, are usually large and heavy, and can starve a system of dynamics if poorly matched to the downstream components that plug into it; a conditioner that uses too small a transformer for the amperage draw of the downstream components is usually the reason dynamics suffer, which is why audiophiles typically avoid active conditioners in front of amplifiers. The latter group, passive conditioners, use no parts that require an AC source (i.e. transformers), are smaller & lighter, and typically do not limit the current draw of the downstream components, making them more suitable for amplifiers. Which approach is “best” is like asking which car is best: ultimately, the only thing that matters is what gets you to your destination.

When speaking with Joe Cohen at Lotus Design Group about the Acoustic Revive Digital Cable that I reviewed some time back, he was beyond enthusiastic when speaking about another product he imports from Acoustic Revive: the RTP-ultimate series of power conditioners. Given how effective I found the non-conventional DSIX digital cable, I was curious about what the designers at Acoustic Revive cooked up for power conditioning. As I found later on, “curious” would be the operative word of the day.

Technical Info

For those interested in the construction that goes into these units, I invite you to review Acoustic Revive’s highly informative web site about the unit:

The accompanying power cord is featured at:

For audiophiles who feel they must sneak their purchases and purchase prices around an incredulous spouse, the Acoustic Revive RTP-4 is going to be “Exhibit A” in hiding your hobby from your better half. By all accounts, it looks like a well built AC outlet strip that you could buy from Home Depot for $30. Trouble is, this thing costs $2250! Lucy, you got some ‘splaining to do!

So, what are you getting for your extra $2k? Let’s run through the design to explain. The RTP-4 is constructed from a solid piece of high grade aluminum to prevent flexing and vibration; indeed, if you took my audio system and fast forwarded 1,000 years, the Acoustic Revive would be the only thing that never degraded with the passage of time or use, such is its build quality. The outlets are custom versions of the excellent Oyaide R-1, featuring the best grip I’ve ever come across, with a high-purity wiring inside linking the outlets to a Furutech IEC. Taken together, these parts would sum to the most overbuilt Home Depot power strip ever made, and do nothing for cleaning the power out of your wall, which is the point of this exercise.

And here’s where things get “curious”: the only element of the RTP-4 that actually “cleans” your power is a proprietary mix of chemicals: tourmaline, quartz powder, and green carborundum, all sealed in the bottom of the unit by a potting epoxy. For simplicity’s sake (as well as good copy), I’ll simply refer to this mix as “magic dust.”

That’s it folks: a couple world class AC outlets in the most overbuilt box I’ve found, with some ‘magic dust’ at the bottom to clean your power. It doesn’t look like much, and I’d have to say that, despite the obvious ‘spare no expense’ build quality, the unit appears to reflect a poor value of your audiophile dollar; again, this product is Exhibit A for those of you who hide one’s equipment purchases from your spouse, as a significant other would never understand why you just spent over $2k on a fancy power strip. You have been warned.

I’d be remiss if I didn’t point out that one of the RTP-4’s outlets has a floated ground, which enables digital gear to be plugged into the same strip as non-digital gear while keeping them electrically isolated from one another. While this is a good trick to further lower the noise floor of a system, it is just that – a trick, and one that might not work in combination with components that require ground to operate; check with your manufacturer, or simply try before you buy, which is sound advice for every component in your buying horizon.

The Acoustic Revive Power Reference power cord is a very unassuming affair; it looks like Darth Vader’s power cord. It’s a solid core, 12 gauge jobber, with some customized Oyaide plugs on the ends, some very high purity copper wire with silk wrapped around them, and a dual-shielding system. One shield is a unconventional copper tube (the cord is still quite flexible) and the black braid sleeve cover is actually another form of shielding as it’s impregnated with carbon paper.

All I can say is “huh?” I generally have an idea of what a designer is trying to do with cabling, but silk as a damper? Carbon paper as a shield? These guys take the cake – make that pudding; as in, the proof is in the pudding.

Listening Impressions

The RTP-4 was able to power all my line level gear, with my having placed the EMM Labs CDSA on the ground-free outlet, so as to prevent digital nasties from finding their way into other gear via common ground). The RTP-4 takes no time to warm up, and its effects were obvious in the most ideal, unassuming ways.

First off, the RTP-4 lowers the noise floor to the point of invisibility, but what made it unique is that silent passages have physical space, and the emptiness is palpable. Live in-studio recordings really demonstrate this: In the studio, musicians key off the decay into silence, listening (or watching) to cues from fellow band mates as to when to kick into gear again. It’s that noise-free space, that palpable emptiness, which defines a good recording studio, where the decay goes down from a pervasive noise, retreating into the corners of the room, and slowly into inaudibility, leaving the musician (and this listener) with the room’s space that was defined by the preceding decay. Needless to say, the RTP-4 delivers this in spades, and better than any conditioner I’ve tried.

I’ve struggled to understand why the RTP-4 did this so well, and I’m left to rely on a pat answer that is ultimately correct: the RTP-4 delivers the lowest level details on the recording, better perhaps than any other conditioner available. Friends, there is a lot of information on those pits, but we audiophiles, despite our best efforts, lose great amounts of it, whether through imperfect data retrieval, signal loss, vibration-induced obscuration, or AC grunge. Is the RTP-4 removing more grunge, or is it simply not committing sins of commission in performing its task?

Really, what I’m asking in the 2nd part of that question is whether other conditioners are making errors in their chosen methods of reducing the noise floor; after all, the RTP-4 is a passive unit with a vibration-immune chassis housing a minimal amount of parts, and there is no perfect part. Is it the other parts in the other units and their less rigid chasses that ultimately compromise the minutest details? Or is it the RTP-4 the pinnacle of removing noise? I’m inclined to think it’s the former. Lots of good products have a non-existent noise floor, which means the grunge is gone, but if the details with the RTP-4 don’t show up with other units, it’s probably because the other units are making mistakes somehow, either through imperfect parts, vibrating chasses, or both.

As I already pointed out, this additional detail is easily heard in the decay into the venue, so it should be as no surprise that the RTP-4 has a remarkable way of placing performers on a soundstage. The previously discussed sense of palpable emptiness is also heard as a performers’ body, the sense of a musician located in a three-dimensional plane. Depth is obvious, thanks to the delivery of physical space accompanied by the low-level details that illuminate musicians’ proximity in that space.

If there were a secret audiophile society for those who hear different tonal colorations with different AC plugs & outlets, I’d likely be the Grand Poobah. I’ve written at length about how various outlets color the tonal palette, noting the golden hue that Hubbells impart, the zippiness and aggressiveness of Acmes, the warmish and sweetness of Isocleans, and the ever-so-slightly cool linearity of Oyaide R-1s. However, the RTP-4 doesn’t have any of the coolness that I’ve heard with R-1s, instead delivering a very even-handed signature, with perhaps a tinge of warmth added. But to cut to brass tacks, I must say I find the tone beyond reproach. When listening to a recorded piano, the instrument I find it easiest to detect tonal anomalies with, the RTP-4 treated me to extended overtones thanks to its superior delivery of low-level details, but whether in the initial development of a note or its decay, I could spot no tonal errors. No golden hues, no whitish blurs, nothing.

So often audiophiles, myself included, are bowled over because the latest change sounds different, as though different is the equivalent of better. Not true. The RTP-4 has an understated presentation of frequency extremes, which may ultimately lead some less critical listeners to prefer alternate conditioners over the RTP-4. Other conditioners, particularly active units, deliver more powerful bass, thanks to the low-resistance AC they deliver to downstream electronics. The RTP-4 does not have the powerful bass that a transformer-based conditioner has, but ultimately what the RTP-4 delivers is more tuneful, accurate bass. Let me explain a theory why: when executing a new design, electrical engineers are not apt to have, in the circuit description, a multi-kVA storage of nearby power external to the unit.

If a component is designed expecting normal AC, providing a low-resistance source of large amounts of juice is a variable not expected in the initial design. The presence of this additional juice is primarily heard in the nether regions, as deep bass requires lots more power (both going in and out of the electronics) than the remaining frequency spectrum. But what you end up hearing is something that was unexpected in the design, and it’s not surprising that its realization is not linear; active conditioners deliver more / deeper bass, but bass that can be tubbier, less articulate, and potentially overpowering. The RTP-4 doesn’t make these errors, instead delivering taut, tuneful, accurate bass, but not the sort of bass that makes for a sensational demonstration or on-the-spot sales.

Perhaps that’s the reason I’m so bowled over by the RTP-4. It simply doesn’t draw attention to itself in any way. It is not exciting, spot-lighting, or thunderous. It simply is clean power with no errors thrust into the equation via suboptimal parts or chassis resonances. This deceptively simple formula lets the RTP-4 deliver music in an organic, unforced presentation devoid of emphasis anywhere in the frequency spectrum. I don’t like to make hyperbolic statements (as subsequent products make me rue my mistake), but I doubt anything will make me believe it is more correct in its overall music presentation than the RTP-4.

Acoustic Revive Power Reference AC Cable

Now, having spoken at length on all the things the RTP-4 does right, it pains me to say that it gets much better when using the Acoustic Revive Power Reference AC Cable (which, thankfully, is hard wired into the RTP-2 unit).

Every parameter I’ve described is simply more so, and it’s obvious the two units were voiced together. One should not dismiss the ‘voicing’ parameter; we’ve all heard about how the Audio Research facilities have Wilson loudspeakers for design and analysis purposes. Point being, some pieces are simply designed to work together, and the Acoustic Revive RTP-4 is designed to work with the Power Reference. Like Abbott and Costello, the RTP-4 simply needs to be paired with the Power Reference to achieve its maximum potential, as a number of different cords I tried with the RTP-4 didn’t deliver the goods the way this combo did. Frankly, the RTP-4 needs to be hardwired like the RTP-2, but I’m running low on my nit-picking list when that’s all I can come up with.

To see the effectiveness of the RTP-4 on amps, I did try the unit with my monoblock McIntosh 501 amps plugged in, using the RTP-4 to feed these amps along with my preamp and CD player. While I got a lot of the same sensations I noted before, I was troubled by a loss of dynamics, which was to be entirely expected. While the RTP-4 is not current limiting in any way, the configuration I was forced into for this test had 4 components on the RTP-4, and the RTP-4 plugged into one dedicated wall outlet. Normally, each of my amps has a dedicated outlet, and I use a third dedicated outlet for my line level gear, which is of such a low current draw that one dedicated line suffices. A fair test would have been using three RTPs, one for each monoblock, and a third for use on the front-end electronics as I did throughout the review; I’m certain this would remove the dynamic constriction I heard when the amps were on the same RTP-4 as my preamp and CD player. Alas, not to be at this time.

Additional Considerations

As I stated earlier, there are many different ways to get to clean power, but it strikes me that this product serves a market that most other conditioners cannot. No, I’m not talking about the “I want my wife to think I’m nuts for spending $2k on an awesome sounding fancy power strip” prospect list. I’m speaking of the group of audiophiles who have to integrate their systems into family rooms and find themselves subject to aesthetic concerns. This unit is tiny, and it tucks neatly behind a rack, or even inside a cabinet beside other components, making it the most physically unobtrusive power conditioner I’ve come across. Audiophiles who crave world-class performance in compromised quarters would be well served to get an Acoustic Revive for audition.

As this is a passive conditioner, its worth pointing out that there are no parts to break, no items to be updated, no risk of failure in this unit. As much as any audiophile component, tweak, or doodad I’ve come across, this thing is meant to last a lifetime…or two. However, with the low part-count, absent of fuses, MOVs, or circuit breakers, this unit is designed to sound good, not to protect equipment.

So Caveat Emptor dear reader, but if you’re like me, your house’s breaker box along with the fuses inside your components will provide you with sufficient surge protection to placate your worries. One final consideration, and this matters to any environmentally-conscious audiophile like me who would not own a class-A amp because of its wasteful use of electricity: the Acoustic Revive is completely passive, and as such does not have any ‘loss’ associated with its use. Any active conditioner will not convert all of its input AC to output AC, resulting in waste and increasing your overall energy usage.


If there were ever a product I wanted to send back with a ‘HAH!” to the distributor, this was it. But slap a wig on me and call me Susan if it didn’t just find a new reference AC conditioner. For a moment, let us consider things unrelated to the sonic performance of the unit, which ultimately factor into purchasing decisions. While I greatly appreciate the tuck-it-behind-my-rack-easily size, the bullet-proof design and durability, and the outright simplicity of the RTP-4, I still take issue with the value for my audiophile dollar. This is considerable money for a sturdy box, 2 nice outlets and some magic dust! So, let us call the two factors a draw and get to the crux of the matter: the sound.

While my tests with amplifiers is hardly fair for reasons articulated earlier, every line-level electronic I tried got better with the Acoustic Revive RTP-4 feeding it. Folks, this thing took my system to levels I had not previously achieved; it alerted me to colorations in the other conditioners I’ve tried, and it delivered depth of image and an organic sense of continuity that I had not previously encountered with any conditioner. The RTP-4, used with the company’s companion Power Reference AC cable, didn’t simply stitch together all the pieces involved with a recording, it simply made one fabric of them.

While making the rounds in the reference-level systems of local audio-friends who use AC filtering systems ranging from $4k to $10k, the Acoustic Revive promptly served notice that it was the superior sounding unit. For the improvement in performance these things deliver, which is ultimately what we audiophiles value, I’m left to consider them a bargain, and I offer the Acoustic Revive RTP-4 my highest recommendation.

In closing, allow me to make and belabor a point: Acoustic Revive is a company you probably haven’t heard of. That said, of the products I’ve tried from them, I can state emphatically that their designs are the real deal, and it’s just a matter of time until you hear lots more from them, and from lots more people like me who are singing their praises.

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