ADD-Powr by Coherence Systems --- Power Conditioning Products

Recent research into power conditioning approaches and products brought ADD-Powr to my attention. This company, and it’s products, were previously unknown to me.

The company, Coherence Systems, is based in Santa Monica, CA. and has been in business for some time.

An introduction and general overview can be found within their ’About Us’ page:

Nordost (in 2008) purchased the QRT technology that these folks developed.

Bill Stierhout is the proprietor / owner and the brains behind the ADD-Powr product line.
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From @scrootable_labs :

"Here’s a set of short clips showing how the sorcer sounds in various positions on our electrical circuit- a familiar loop, first bounced from a DAW without any processing, then played through a Mytek Brooklyn DAC via a MADI-AES chain through an analog patchbay into a Brooklyn ADC:

the tone for the recaptured track is comparable with the Sorcer in and out of the system, but you can hear changes in the way the image is rendered- those shifts are mostly improvements, IMO, with a more coherent response as the unit’s engaged.

the sonic profile shifts radically when the unit is placed closer to the other gear and fed by a balanced power transformer. becomes euphonic- still desirable for certain applications, with a bit more ping on the top, a rounded kind of muscle to the midrange and extended bottom [there are another few positions I’d tried where I didn’t like the results, didn’t capture them in this specific test.]

the test is useful in also exposing some of the shortcomings with the conversion and signal path (some softening to the transients in the middle of the image, etc) but the effect is comparable using higher-end converters. I will be replicating the test in a more controlled environment with shorter HQ cable runs and improved conversion next week.
From @cohsystms :

"Hello Josh,
Thank you for your comments. I trust that you are enjoying the x4.
Indeed, especially in the last clip there is quite a remarkable sonic improvement over the first two. You used the word "euphonic".
That says it all.
You are finding the best locations for its use in the studio.
Indeed close to the electronics will have the strongest effect.
And yes, it exposes flaws in the signal path and the remedies used to correct them.
Try location near the monitor amps or in the pro tools or computer room,if there is one.
Thanks again for your support,


Coherence Systems / ADD-Powr"
From @sonicshading :


I find it interesting that you have declared your sound right, after repositioning the ADD-POWR unit. Finding anomalies with the original source material (when the ADD-POWR is in the circuit) is enough for most engineers to avoid tweaking it. I suggest using a quality spectrum analyzer to see what you declare as transparent.

I would never spend my time or my clients’ time tweaking an AC power product to supposedly affect my source material. A better Idea is to remove all gear that isn’t being used and create an acoustically sound room without serious modes. Using a mastering desk that gets out of the way and allowing speakers/monitors to be positioned without early reflections distorting the original signal.

My hearty recommendation for those interested in pursuing power distribution and how it can affect sonic qualities in a system is to start with a materials based approach. Before diving into the deep end like the ADD-POWR, you deserve to hear what different outlets/plugs sound like, then all the various platings...and using different types of passive EMI/RF absorption materials. Try listening to various power outlets and plugs that have better conductive and tight griping alloys, or shielding power cables tied to wall ground, or various passive EMI/RF absorption material. I feel this is a good starting point.

By no means do I believe everything needs to be measured to be proved, but in the case of the ADD-POWR- it just confirmed what we were hearing.

I believe Garth Powell previously at Furman and now Audioquest does incorporate Symmetrical power in their new designs. I would recommend at least listening to power conditioners made by people who have worked in this field their whole life.

You see the ADD-POWR does change the sonics of a system, and if you like it great...It is just not a proven or even fully understood technology. Not to mention- I’m not interested in radiating EM-fields in my room... I’ll keep the EM-Fields to the ones my own body produces;)

Btw- the add-powr stuff is related to other health technologies that emit EM-fields and claim to help order the chaos of complex electrical systems. curious.

It does sonically change your sound, but in our case it was not for the better..."

From @cohsystms :

"Re: sonicshading

 I find it interesting that you have declared your sound "right", after re-positioning the ADD-POWR unit.

The Sorcer is location dependent. Acute differences are perceivable.
Indeed anomalies will be discovered, and, as verified by spectrum analysis, will confirm what the ear discerns.

Preliminary spectrum analysis tests reveal changes as conducted by an independent, ex-Harmon engineer, looking at the the noise floor of a pro JBL amplifier.

There are different ways to skin the cat. The AC power is the basis of the pro audio recording, mix, and media playback environments.
Acoustic designs are significant as well. But once an acoustic design is settled, then it becomes the listening space standard.

A client should embrace what the ADD-Powr can do to his work - at any phase of the recording process.
Yes, it is a new "standard" or "reference" by which the engineer needs to be comfortable with.
This has been borne out by many customers. Their comments tell the story.
Once this transition phase has been completed, then the level of the recording, mix, and media product will rise to a new level of excellence.

A materials approach can only go so far as to affect power. All those methods mentioned are indeed valid and worthy of pursuit.
But it still does not address the AC reference per se, and as direct as ADD-Powr does.

The other companies simply address other aspects of AC power that ADD-Powr does not.
ADD-Powr is compatible with most other approaches including balanced power systems, and power regeneration designs.

I beg to disagree. It is an understood and proven technology.
We are surrounded by fields virtually everywhere, one can't deny it.
Energy fields (more of the electric type than the magnetic type, or more E than M) are a good thing, not only for electronics - audio systems, but also for us, the occupants of emf environments.

And yes, there is nothing wrong with developing technologies that started in the realm of biomedical sciences.

Your opinion is appreciated.
It's regrettable that the Sorcer did not appeal to your ears."
From @scrootable_labs :

"For my part, I was able to discern and manage a range of clearly perceivable harmonic effects (subjectively positive and less-positive ones) by following its general specifications- which involves shifting its position around as needed.   Some of the effects were desirable, and repeatable (though I can't replicate them with any other form of DSP or analog processing in our studio.) and some were unnecessary for my application.

In its current position, the Sorcer has a beneficial effect on the the way the stereo image resolves from end to end and front to back. It provides an additional sense coherence in tracking individual elements within a given mix- really understanding the color of a given attack or the profile and tail within an ambient space, for example. it's been useful in dialing in the monitoring for our space and tends to expose minute issues, say, with speaker placement and it's very helpful when assessing phase relationships and spatial positioning within a mix.  

Currently, the sonic profile is harmonically similar with the unit on or off- less of a difference than, say, switching between one desirable A/D converter and another (or even one after-market IEC cable and another.)  Having found a more optimal position and cabling config for the device, it becomes somewhat academic to then run extensive harmonic analysis to assess effects that aren't impeding our workflow, but I don't mind Nugenizing some tone and sharing some data visualization for folks to study.  I'll be replicating our study in a more minimal setup based around a Maselec console with wireworld interconnects & will add additional info as that process comes together as well."