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EquiTech 1.5RQ Balanced Power Review

bibio

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What balanced power does is:
1. It eliminates common-mode E field radition from the mains. I imagine recording electric guitar would benefit from this if nothing else (high impedance circuitry where shielding is not always all that great - even if the cable is alright that doesn't mean the instrument itself is).
2. It reduces voltages to ground. That's why it's used on ships.
3. It eliminates power supply leakage currents from IEC Class II devices with SMPS mains filter topologies originally derived from Class I jobs (i.e. L and N capacitively coupled to secondary-side ground only as the PE connection got axed).

If this makes such a major difference in studios even outside item #1, I do have to wonder how many devices with AES48-2005 compliance issues are still out there in this day and age. They no doubt would still have been very common when RaneNote 151 was written in 1995. Otherwise I don't think there would normally be long runs of signal wires right next to mains wiring that could push CMRR limits in the face of item #1 - right? (This may not even be up to code depending on where you live.)
That's the most accurate description I've seen!
Just from a live audio perspective, I know of a major world-touring artist that brought their entire audio system to the US. To keep the existing touring infrastructure they used a very large step up transformer so they essentially ran their entire audio system at 240v in the US. That's PA system, mixing desks and backline. By all accounts, the lack of hiss and noise for the PA was staggering. The first comment from everyone on the job was "is the PA switched on?" They had toured the same rig throughout Europe (with no TX) for several months and had become accustomed to the background hiss. I should also point out this was using some of the most modern, top-of-the-range live audio equipment that money can buy.
The guitar rigs also became much quieter, it was especially noticeable with the vintage single coil instruments. This system wasn't using balanced mains just transformer isolation.
If you're ever had the pleasure of staring down a 450ft 48ch analog multicore trying to find hums and buzzes, you'll quickly appreciate how useful mains isolation/balanced power can be. Sometimes audio tx's and pin 1 lifts alone don't resolve the issues. It's definitely not always the solution and it carries multiple risks but for certain situations balanced mains can save the day.
 

misterdog

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I use an Airlink Balanced Mains Transformer to feed.

SMSL M400 >Topping Pre 90> Benchmark AHB2 > Quad 989 ESL's (in bespoke steel rigid frames).

I have no complaints.
 

Mikko Dee

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I’m glad I bought mine at a very significant discount from a recording studio that closed…. Wow, I’m surprised after reading the test results.

Then a quote from long ago came back to me. “In nature there are neither rewards nor punishments; there are consequences.”

Umm hmmm………..
 

Mikko Dee

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I know a number of audiophiles who have bought their products including the in-wall permanent ones. Not one of them has done so because they had ground loop problems. They buy them precisely for the claims the company makes: lower noise, veil removed, more analog sound, etc., etc. As I quoted, the company caters to this market just as well as the next guy selling classic power filtering products. And that is the claim I tested. Indeed the owner had purchased this unit for these reasons.

As to them doing some good in professional market, there are plenty there that follow the crowd and buy such things. If there is grounding problem, I would go and find the sources of those and fix them than resorting to such boxes.
You can add me to that list…..I’ll be putting my unit up for sale shortly.
 

Mikko Dee

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A big problem with the foreclosed buildings in Detroit is they don't have any copper in them, and were damaged by its removal.
Not too long ago, there was a news report of a young guy who died using bolt cutters chopping into a still active power line. That was the end of his criminality / life.
 
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audio2design

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Maybe the improvements are higher frequencies. So let's expand the measurement bandwidth to 1 MHz and see what we get:

View attachment 140962

Nothing. Everything is as bad as without 1.5Q.


This result does not look realistic. I suspect you are measuring with 0 load. There is no way the transformer has a bandwidth this wide, so drops at high frequency must happen.

However if you have 0 loading, capacitive coupling input to output (and in your measurement) could dominate.

I would ensure you are placing some reasonable loading across your probes to provide a more accurate measurement.

I still wouldn't waste money on a center tapped 1:1 transformer.
 

audio2design

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Company talks about better power factor. What is power factor? Ideally your load would consume current at proportional to voltage. That is, the two are in sync. That only happens for a resistive load (e.g. a traditional light bulb). Many electronic devices we have use current out of phase with voltage. Resistive loads produce a power factor of 1.0. Anything else is a reduction and makes it harder for the power company to deliver energy to you. Let's measure the Purifi amp's power factor and efficiency of the 1.5Q:

View attachment 140964

As we see, the power factor by itself is quite poor at 0.38. There are switching power supplies with power factor correction. The hypex one that Purifi is using is not one of them. EquiTech 1.5 improves this to 58%.

On the down side, there are losses due to the transformers in this box. Power consumption goes up to the tune of 31%. So the box gives you one thing, and takes back another.

Note that in US you don't get any benefit from using your power with 1.0 power factor in residential setting. In commercial installations however, you could get charged extra for low power factor.


In the measurement you did at low power the improvement in PF would be mainly due to the very large parasitic load of the transformer added to the existing transformer. Hardly a "benefit" :)

At higher loading of the amp I expect the transformer may have a small improvement in PF due to the leakage inductance of the transformer and limited bandwidth reducing higher harmonics. Gotta love it when marketing turns faults into features :)
 

audio2design

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Well... my previous workplace had something like that. It allows us to work on power supplies without making a neutral-to-earth short trip the floor every time. And boy it happens a lot because we only had one such transformer while we have many staff working simultaneously. The good part is, now I know how to easily test whether your house's GFCI/RCD is working.

Most of the outlets in my lab are isolated. Makes for much easier and safer lab work. Nice low leakage transformers. Barely a buzz from a miss-touch :). Makes using scopes much easier too. Only need noisy differential high voltage probes rarely.
 

audio2design

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So, if we want to protect our equipment and feed it good AC power, what exactly should we be buying?

I'm looking at Furman products but am at a loss as to which one(s) would represent prudent investment in protection (and if feasible reproduction quality).

Mid end Furman use inductive/diode/capacitive surge suppression ala SurgeX plus MOVs. Best is to have whole house surge suppression then additional protection at the point of load.
 

audio2design

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I think there is a lot more here than is being covered.
Looking at the manufacturer's site there is a lot of information, and a lot of it actually makes sense. However the sale of these devices for domestic use is not something that makes any sense. As Amir notes, a balanced mains feed does not meet code in the US for domestic use. The manufacturer has an FAQ that quotes the code, and is quite clear about this. However, their web site has two parts, one for commercial use, where this FAQ can be found, and a domestic side for AV applications, where nothing is mentioned about domestic use being a violation.


So why is the device built as it is?
Interestingly they claim very high quality steel is used for the core. Which is odd. Usually you do that to improve frequency response. Which with a power isolation device is generally what you don’t want. Indeed Amir’s results show this. However the rationale seems to be that they don't want the transformer core to introduce distortions of the waveform itself. They trumpet a bifilar wound secondary the ensure avoidance of asymmetric waveform distortion. The device is designed from the outset not to filter external noise. So Amir's measurements actually confirm the manufacturer's design goals. This isn't a filter, and should not be judged as one.

I looked into this a while back. You can't have installed balanced power with a separate ground in a residential installation. I think a single box that uses the same ground for the output (center tap) as the input AC ground "may" technically be acceptable providing it had a socket output and cannot be hard wired. It's really no different from a plain isolation transformer with integrated socket that share the same AC ground input and output.


The bifilar winding will have have capacitive coupling. Under high loading that should be less of an issue. Even good steel should have more high frequency drop that the measurements.
 

audio2design

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We are talking about a 60 cycle ground hum that can be heard with nothing playing and will be printed in the recording.

Many issues in studios including high impedance inputs, and simple parallelism. All those y-caps leak and add a ton of equipment ...gets nasty. We used medical grade supplies for some of the studio equipment we supplied due to the very low leakage currents. Customers loved them!
 

audio2design

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Audio equipment makes no assumptions about clean AC power. It converts it to DC and filters it as needed for its application. So it doesn't matter how dirty the AC power is.

Now, if you have an industrial machine shop on the same feed maybe you get interference from that. But office parks where studios are located are not such. And even if they were, such devices will be of no help, other than randomly changing something that "fixes" the problem.

The issue is rarely the line/neutral feed. It's leakage currents that get into signal lines. High frequencies go nicely through leakage capacitances and intentional EMI capacitances.
 

audio2design

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That has not been my experience. I worked at a studio that was across the street from a metal fabrication shop that polluted the studio's AC until closing time every M-F for years. Guitar amps, monitor systems, and tape recorders were the most affected. When a 75 amp Equitech wall mount unit was installed the problem disappeared. Trust me, no one wanted to spend the 10k but it had to be done.

Time is money with a studio. You don't have time to chase noise issues with every new set off equipment. Better to just isolate and be done.
 
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amirm

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The issue is rarely the line/neutral feed. It's leakage currents that get into signal lines. High frequencies go nicely through leakage capacitances and intentional EMI capacitances.
Why would leakage currents get into signal lines of balanced interconnects?

That aside, you have any real data to share other than this and that theory?

And do you have any business interest in this field?
 

audio2design

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I did not see a separate ground on the load side of that transformer. Separate grounded and grounding conductors on the line side of the transformer would help getting rid of much of the junk shown on the test plots.

Thanks DT

I think this is how they get around NEC compliance but don't quote me on that.
 

audio2design

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In consumer electronics, particularly surge protectors, the MOV varistor size employed is small enough that eventually failure is expected. Other applications, such as power transmission, use VDRs of different construction in multiple configurations engineered for long life span."

https://en.wikipedia.org/wiki/Varistor

Whether consumer surger protector or consumer electronics, the product is designed to a spec and tested against a recognized standard. Surge protectors are tested to a number of hits at high energy. Consumer electronics if tested to a standard are typically tested for more strikes but at less energy indicative of what they would typically experiece. They all will fail eventually but 5+ years of service is to be expected.
 

audio2design

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Like this? https://www.grainger.com/product/TRIPP-LITE-1-8-kVA-Hospital-Grade-Isolation-1AYB2


View attachment 141398 View attachment 141399



Then I only "wasted" an extra $300 when I got my rack mount sized input and output breakered input and output voltage displaying 10 outlet GFCI protected ETL Listed 1.5RQ years ago (used).


View attachment 141397


And I fully expect to get back my entire cost when/if ever sold.

The hospital grade may have lower leakage to meet medical specs.
 

audio2design

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I've dealt with 20kva systems that cost around 10k. More importantly, I've also dealt with multi million dollar 100Gb carrier grade aggregation devices that have been impacted by literal free radicals. This is not a joke.

Everything you are dealing with is narrowband. All those optical transceivers are relatively narrowband and the digital is all differential and larg(ish) signal levels. Because they are relatively sensitive to one type of noise does not mean they are sensitive to other noise sources. While the equipment is sensitive you don't have a lot of noise sources in the bandwidths of interest and being high frequency easy to shield for. And yes I did do some contract R&D (joint university/industry late 90's early 2000's) on 10gb optical transceivers so I have some awareness of the issues.
 

audio2design

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You take all that gear and pass analog through it? Really? Well there's your problem. Mic's and recording devices should be digitized immediately in the recording room. EVERYTHING else should be in the digital realm until hitting the DAC to your monitor amps/speakers.

And yes, I've absolutely had to measure in data centers. COAX, as well as Ethernet. Noise isn't a thing to us. If it is found, it's a REALLY dumb thing that was done. Poor crimp, bad bond, kinked cable, a million and one things.

Now have people come in and change the setup almost every day ...

You are comparing apples and oranges.
 
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