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PSU1 Enigma Micro-Signal Power Supply

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Graham Slee View Drop Down
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    Posted: 28 Jun 2018 at 7:54am
Introducing the PSU1 Enigma Micro-Signal Power Supply

I've been holding off announcing this whilst some beta testing has been taking place, but it would seem that the above named power supply is actually delivering the audio goodies.

Perhaps it's now time to announce it?

Yes? OK, here goes...

What's in a name?

Why Enigma? Well it is one, because when I try and explain it to you, you might find it as unfathomable as I almost found it myself.

It is not however psycho-acoustic BS!

It was indeed "a very difficult code to crack".

Also, it may well be limited edition because I don't know when the makers of a particular component will call time, and as far as I can make out, there is no alternative. This is not a sales gimmick!

Price?

I'll be upfront about this, it is not cheap!

It is a tweaked up PSU1 (as I will explain) and will retail at £385. Yes, I know, that's more than twice what a PSU1 costs. Surely the components aren't that expensive?

They're not, but time is also money, and I usually go to all this trouble and get paid back through sales, but this has taken an inordinate amount of time and the risk is sales simply stop due to one manufacturer pulling out. I will repeat, it may well be limited edition because I don't know when the makers of a particular component will call time, and as far as I can make out, there is no alternative. This is not a sales gimmick!

What's it for?

It was developed for the Accession MC, and that's all I will be recommending it for today.

It might bring benefits to other products, and that may depend highly on other items in your system which might or might not allow you to hear any benefit

I noticed an improvement using it with my Majestic DAC but that was playing one well known FLAC rip.

What does it do?

Regular readers will know my personal aversion to moving coil. My records never sounded quite the way I expected with moving coil. Was it because MM didn't reproduce them properly and I'd been so used to MM in this way like an addiction?

I'd have to disagree. I have CD and FLAC versions of many of my records to compare MM results with, and MC was always the odd one out.

I had to keep on trying because there had to be something that would make a difference, and that something turned out to be in the power supply.

For me "the Enigma" makes MC listening using the Accession MC a real pleasure.

In what way?

Going back to when I launched the Reflex and Revelation M versions, I used to talk about "pronunciation" and the way stages (and other items of equipment) either "pronounce sounds properly" or not. Note here I am using quotation marks - "pronunciation" is my way of explaining what I mean. Perhaps detail retrieval would explain better?

And what I mean is I like to hear not only the lyrics, but how they're expressed. If you have a load of instruments going on at the same time, that's hard to hear.

And my other MC moan is MC brightness... why? Surely high fidelity doesn't mean that?

But now, with the use of the PSU1 Enigma with the Accession MC, I'm suited down to the ground, so much that I'm actually enjoying the Hana EL currently on the turntable, and I have no inclination to change back to MM anytime soon.

Now that's saying something!

Shielded Cable

One of the first things you'll note is the shielded DC cable.

So is that it? Absolutely not!

A beta tester asked that very question - a valid question - so I said give it a try with a normal PSU1, and it did not do the same.

The shielded cable is part of the "solution" but it is not the solution.

How does it work?

First a look at the MC cartridge

MC outputs on average one tenth of what an MM does and even less with some more-exotic cartridges.

Also factor in the output at -60dB. Yes, according to some reviewers there are sounds so soft way down in level, arguing that it is within the dynamic range of vinyl. I'm not disagreeing with them.

Also realise the advertised output is stated for 1kHz. Being a constant velocity device its output falls from 1kHz at 6dB per octave, and it also rises from 1kHz at 6dB per octave.

If it were not for record EQ (RIAA etc.) the output at 100Hz would be a mere tenth of that advertised, and at -60dB, one ten thousandth!

Going the other way it can be around 13 times bigger at 10kHz with just 2dB headroom added in.

So far we have a dynamic (versus frequency) range of 102dB. That's massive!

The record's RIAA EQ helps through its "shelving" by 12dB, making it a bit better at 90dB - still massive.

90dB describes a ratio of 31,623:1 - the ratio of the loudest 10kHz signal to the quietest 100Hz signal.

And here we have only covered 100Hz - 10kHz out of the usual 20Hz - 20kHz.

In a real MC cartridge, say one advertised as doing 0.2mV at 1kHz, it can range from a few nano-volts to a few milli-volts. Roughly around a million to one.

The MC phono stage

What we're doing is basically asking the impossible really. I've seen scientific engineers struggle and give up with voltages in micro-volts, never mind nano-volts.

This is because we're right down in the noise - the stuff generated by all electronic materials whether they be semiconductor junctions, resistors, capacitors, even wires (due to inductance), you name it.

But if we managed to fight off the generated noise by making clever decisions, we then have to consider real world effects.

And here I mean the power supply. It's not about brute force, it's about where the signal current flows and ensuring its flow won't just allow the "survival of the fittest". The fittest being the stronger signal. We want all of it!

The Accession MC is a different build but uses the same board as the Accession MM version. It is so carefully laid out with solid ground plane, and decoupling capacitors which guard against high frequency oscillation due to stray inductance on power pins.

Want to read up on this some more? Take a look at https://pdfserv.maximintegrated.com/en/an/TUT5450.pdf - not an identical  application, but it applies to preamplification in as many ways.

Even with the solid ground plane, additional hard wired "star earthing" was found to improve detail retrieval (the wires lowering the impedance of a solid ground plane), but only on the MC version (all Accession MC's have this).

On the link I just gave you, and after the introduction, it talks about following the current, and I'll quote a little here:

"Remember that we call a collection of connected electrical or electronic components a "circuit" because currents always flow from a source to a load and then back via a return path—a circle of sorts. Keeping in mind where the current flows, both in the direction intended to do the desired job as well as the resultant return current, is fundamental to making any analog circuit work well."

And just before anybody picks up on the word "direction", the direction involves positive and negative signal current. I know it's AC and so do Maxim!

So after being "star earthed" and still not reaching my standards as regards absolute detail retrieval, what else could be standing in the way?

The Enigma question - where does the signal current actually flow?

DC current flows from the power supply, round the circuit, and back to the power supply. That is the obvious bit.

But we are interested in the AC signal current being drawn by the circuit. This also starts at the power supply, and unless at some considerably high frequency where local bypass capacitors come into effect, it has no other option but to flow back to the power supply.

In a mains derived conventional transformer power supply, the reservoir or energy storage capacitor(s) become the dominating source for any signal above the rectifier frequency which is 100 or 120 Hz for a full wave rectifier, depending on mains frequency. As frequency increases the reservoir capacitors become more the dominant source.

Below the rectifier frequency (below 100 or 120 Hz) the entire transformer/rectifier/reservoir circuit is source.

Because instruments can be identified it must mean they have signatures which are a mix of harmonics and intermodulation, so a bass instrument fundamental below 100 (120) Hz might well have some or most of its signature in the range where the reservoir capacitors are dominant.

Therefore the vast majority of musical signal has the reservoir capacitor(s) as source. And this being so, must return to that exact point?

Kirchhoff's loop law on the conservation of charge confirms that current must flow back to its origin.

Is there any other route such as local decoupling which signal current could take instead? In other words, can we eliminate this power supply effect within the preamp stage box?

It all depends on the impedance of the power supply. Preamp stages are supplied via a voltage regulator of some sort which is essential to expel power supply ripple and glitches on the supply.

For it to perform its regulation a very low output impedance is implied. The actual output impedance will vary with current drawn, but values of 0.02 ohms are often quoted in specifications.

If we stick a (big) 1000uF capacitor on the voltage regulator output the corner frequency will be 8kHz. Surprised?

We would need in excess of 50,000uF to reduce that to 100Hz. It is doubtful the regulator would perform with such a capacitive load, or even start.

But won't signal current flow back up the voltage regulator itself? No, if we follow the current flow you will find it cannot. Examination of both series and shunt voltage regulator reveals the same outcome.

One suggestion which on the face of it might work, is a capacitance multiplier circuit. An exhaustive discussion of its workings would be inappropriate here as this is already a very wordy piece to read. But I will say I have tried these in several circuits and each has led to various levels of subjective disappointment. I am willing however to discuss the workings of the capacitance multiplier if pressed.

That aside, we have to conclude that the majority of audio frequency signal currents find their way back to the power supply, that being the path of least resistance.

In the range 100Hz to 8kHz (8kHz because of the voltage regulator decoupling referred to above) its origin is dominated by the reservoir capacitors. So here we should expect to hear the biggest improvement. I cannot risk an improvement which is so subtle that few hear it. And it has after-all been a mission to improve the performance I get from moving coil.

So what effect do reservoir capacitors have?

The first thing we note is they are electrolytic, universally despised by the "all capacitors are bad" brigade, but physical science being what it is, nothing can be done to change this fact.

The first thing we have to realise is that all frequencies of signal current (100Hz to the 8kHz we established earlier) flow through these capacitors. They dominate at these frequencies. The signal current must, by Kirchhoff's loop rule, actually flow in them!

But anybody with an ounce of understanding of electrolytic capacitors will know they are not very linear when it comes to audio frequencies. And a number of fixes have been proposed in a bid to improve this.

Fixes include "cap-rolling" where numerous different makes of electrolytic capacitors are tried, and listened to. Other fixes are bypassing them using film capacitors.

It should be obvious that I've already been there, as the existing PSU1 is known to bring an improvement over nearly two decades of "stock" power supplies, and with all the products which work with it.

But by understanding where signal current flows the problem can be overcome.

All capacitors have a capacitance versus frequency curve (whether published or not), which will falls off with increasing frequency, and this is the non-linearity.

(some have proposed batteries but they exhibit a far worse curve)

If different frequencies must pass through these capacitors as in music, each frequency in-effect passes through a different capacitance.

Quote taken from "Audio" Feb 1980:

"It is not at all hard to imagine how a capacitor whose value actually changes with frequency might distort an audio signal's integrity, particularly with regard to phase. If we can visualize the complex frequency relationships of music passing through a capacitor (it doesn't really), while impedance is simultaneously changing with the complex frequencies of the music, it is possible to appreciate how it can be relatively easy to upset the subtle harmonic/fundamental phase and amplitude relationships."

The answer therefore is in the choice of reservoir capacitor. What is wanted is the flattest possible capacitance versus frequency curve, and for that we either need to see the curve, or to understand the factors which make it flatter, and in so doing we are able to obtain and use suitable capacitors.

I was surprised to find how difficult putting this into practice was. Manufacturers of such high value capacitors tend not to go into such fine detail. For them only some of the required factors are of interest, which tends to suggest few designers demand such information, and therefore, few designers understand such workings.

In the event I was able to track down just one value from one manufacturer which complied with all the wanted factors. The existing capacitors of a PSU1 were changed for them, and the sonic improvement was immediate.

Rather than stopping just there I wanted to try to make the improvement more noticeable, and where the use of a shielded cable had proved fruitless with a regular PSU1, on this occasion it "zoomed-in" on the improvement.

It might also be down to the choice of cable and its dielectric (insulation) which anybody studying capacitors for high performance will realise, is, in itself capacitive. Not only that but different dielectrics have different degrees of "memory" - they don't give up electrons that easily.

The result is the PSU1 Enigma Micro-Signal Power Supply. The above should explain the choice of name.

The above explanation has taken me the best part of two weeks to compile and to make it make sense without going into mathematical proofs or making it overly technical. I trust I have not lost you along the way.

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Ash View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ash Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 2018 at 8:34am
Jeez, I think I need to go back to school and start my education all over again...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote morris_minor Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 2018 at 11:04am
For the past month or so I've been beta testing the Enigma ps with my Accession MC. Aside from the colour of the cable this looks just like any other PSU1. But for the AccMC though it really does the business of improving what was already a stellar sound. 

The effect of the Enigma is to bring the sound even more into focus - not making it "sharper", but just more defined. (Think Blu-Ray video versus DVD). Dynamics are also improved. This was most notable with Pink Floyd's "Division Bell". I'd just completed a video of a few tracks from this when the Enigma arrived so I re-ripped the audio and compared the waveforms. Sure enough, with exactly the same level into the ADC, the loud peaks were obviously louder visually, and sonically this translated into not only a more exciting sound but one where the inner detail within those peaks was more noticeable, more tangible.

This doesn't only benefit rock music; jazz and classical stuff I've played has even more immediacy and going back to the vanilla PSU1 is like dialling down the colour saturation and contrast slightly. It's still a very, very high quality sound, and if you've never heard the Enigma you'll be very happy with it. But . . .  once heard!

Having been around on this forum for many years I've known of Graham's antipathy to MC cartridges. It seems that the Accession MC + Enigma ps has performed a miracle - not on the road to Damascus maybe, but on the A6195. Wink

I've been an audio cynic for quite a while. Cables were just bits of wire until I chanced on Graham's CuSat, Lautus and Spatia offerings. Power supplies were necessary but boring until I swapped a plug top supply on my then Solo SRGII with a PSU1 I had on loan - I thought nothing of it until I swapped back and my headphone sound shrank and became duller. 

From anyone else the Enigma would have all the hallmarks of creative marketing, but knowing that everything Graham releases is based on sound electronic design and painstaking testing to standards very few makers seem to aspire to in these days of quickly churning out products to keep the bottom line afloat, it is no surprise that the Enigma really does work. Graham says that it's not cheap. The Accession MC isn't cheap. But their combined performance is in such a different league that comparisons with phono amps costing 2, 5 maybe 10x more would not be unreasonable. You may miss out on fancy bling-tastic casework, microprocessor switching, remote controls - but for the music lover who's gone to the dark side and uses MCs the AccessionMC/Enigma combo is a no-brainer.


Edited by morris_minor - 28 Jun 2018 at 11:05am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richardl60 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 2018 at 8:22pm
As ever a well researched and thoughtful solution to a particular issue and what appears to be a niche but excellent product, well done Graham.
If as I read this correctly the capacitors are electrolytic and as I understand it degrade over time?  If correct where does this sit with either leaving powered up 24/7 or the potential inability to replace them in years to come?
 
It is good to see that Graham has investigated the use of the upgraded DC cable; which focuses on eliminating a specific problem.  In my experience going back 3-4 years the 'standard' AC & DC leads supplied tended to sound a little thin, splashy and lacked body, naturalness and fine detail.  Whilst not suggesting either would necessarily work around the problem Graham identified these do remain a relative weakness within the excellent standard units.  Differences were not huge (nowhere near the significance of other mains leads) but collectively in my case two upgraded mains and 1 DC lead (other is captive to from Elevator PSU) did provide a smoother, more integrated presentation with greater naturalness and notably less splashy and better separated mid-high frequencies.
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BAK Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 2018 at 10:08pm
morris_minor wrote "sound electronic design". I translate that to "a truer audio reproduction design".

There are "bad" electrolytic (and other) capacitors being used in electronics of all kinds. All electronic components can leave their signature on a signal. By selecting "good" components that compliment each other, this can cancel most of (or all of) that signature. Each part of the circuit is selected to contribute to the synergy of the desired result.

 There are ways to select parts to compliment each other AND extend the life expectancy of all circuits.
This design process involves much more R & D and testing. A price of £385 for Graham achieving this design is cheap.


 The power source is very much part of the signal produced in all electronic circuits.
After all, each active amplifying component is really just modulating the power supplied to it.

 I feel Graham has worked his "art" again to produce the Enigma!


Edited by BAK - 28 Jun 2018 at 10:14pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 2018 at 10:16pm
I was also a beta tester on this project and recommend the Accession MC with the Enigma Micro-Signal PSU1. Please try it and hear your music properly through an MC cartridge.

In the testing I listened extensively to the AccMC, EXP and AccM with various PSU1 combinations quickly swapped over. I also tried various low voltage cables including the standard PSU1 cable, the new shielded cable and some of my own with chokes on them. In my opinion the new cable helps the PSU1 with the AccMC and the EXP stages but it is a fraction of the benefit from the Enigma PSU1 itself. I think there is a synergy between the Enigma and the new cable, with the cable being the finished touch adding a little extra or rather not adding anything which I'll come back to. Crudely put the EXP with Enigma and new cable gets a bit closer to the AccMC, the AccMC and Enigma/cable is something else entirely.

Unsurprisingly I did play a lot of music on vinyl that fortnight and found it all sounded much better. Frankly I enjoyed listening to everything I played and it wasn't just my favourites. On rock tracks the tracks in the mix were easily separated but sounded right together, with the dynamic sound of drums bieng most remarkable. Cymbals and other percussion sound much more lifelike, rich not white noise or the sound of metal sheets being hit - hits on the bells sounded right, they chimed and I could hear the stick hitting. On good orchestral recordings it is like being in the hall and some opera I picked up whilst away was presented in front of me with the singers moving around on the stage. The AccMC delivers the promise of MC, fine detail from low moving mass bringing out more of the music. With the Enigma PSU1 it is just the music - pure without the pollution of environmental noise.



Edited by Fatmangolf - 28 Jun 2018 at 10:19pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 2018 at 10:42pm
Originally posted by Richardl60 Richardl60 wrote:


If as I read this correctly the capacitors are electrolytic and as I understand it degrade over time?  If correct where does this sit with either leaving powered up 24/7 or the potential inability to replace them in years to come?


The projected life according to http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx for the rated use is 131,400 hours or 15 years approx.

Hopefully by the time I'm 78 I will have worked out what to do... Wink

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