Hi everyone,
This is quite possibly the most verbose and gratuitously long post I have ever written. For those with little time or patients, the executive summary go something like this:
If you are an Orion owner and otherwise have a resolving and engaging system (e.g. use AKSAs as power amps), stay tuned ‘cause Hugh Dean is about to rock your world with a new power supply topology for the Orion ASP (actually, a universal +/- 15V power supply, but the experience related in this post is all with my Orion system).
For those with a little more time, and who are happy to meander along as the story unfolds, let’s start at the beginning.
In regard to his Orion Analogy Signal Processor (ASP) Siegfried Linkwitz seems to imply that power supplies do not make a notable difference to the sound. In fact, he has built a certain degree of mystique around the notion that cables, amps and power supplies don’t matter with the Orions. Whilst if flew in the face of all that I had learnt, “fare call”, I thought, after all, he is the master designer [I consider the Orion nothing short of a master piece – the embodiment of a lifetime of hard won wisdom].
Still, something had always bothered me about my Orions; they are articulate, fast, provide good soundstage width, but I was always an arms length away from aural satisfaction. Firstly, in complex midrange passages, there is a tendency toward a slightly muddy presentation. Instruments collapse upon one another and the detail becomes difficult to distinguish (perhaps this is why I found myself listening to a lot of simple acoustic music on the Orions…the explosive speed is highlighted, without exposing the midrange weakness). Secondly, they just lacked warmth…like the house of an obsessive-compulsive; detailed, immaculate, everything where it should be, but an emotional lack of homeliness… I loved my speakers, but was not in love with them.
Earlier, whilst researching power transformer configurations for my initial build, I stumbled across a group of Naim enthusiasts on the ‘net. Several of their suggestions were incorporated in my ASP power supply design; namely the use if one EI split boffin transformer for each rail and grounds kept separate until a star earth point at the load (not sure how much value this has added, but never-the-less, this is how my power supply is put together). One of the other common themes from this group was the value of Jung-style super regulators, and in particular, the regulator refined by Andrew L. Weeks who produces a lovely incarnation of very-fast feedback regulators.
Fast forward a few months…
As a dabbler, I am always looking for something new to do; truth be known, it is more from a compulsion of making things than a true obsession with audio that lead me to owning a set of Linkwitz’s babies. Finding myself too skint to build my next set of speakers, I was on the hunt for my next project. “I might have a crack at some super regulators for my Orions”, thought I one day. Andrew Weeks (nice fellow, by the way) had just organised a group buy on Pink Fish media web site, and I couldn’t resist the temptation. A couple of weeks later I installed a set of super regulators on one side and sat back to listen. What I heard was a marked improvement. It was as if someone had teased out the instruments like an 80’s fringe and given volume and space to what was previously a compressed mass. “Possum”, I said to my wife, “have a listen to those two speakers and tell me if you can hear a difference?” “That one sounds muddier”, said she and pointed to the 7x12 regulated side. Well there you have it… an unbiased witness had noticed the same thing I did. So the second side got the treatment and what resulted was more beautiful than I had started with. It did seem, however, that the weight and dynamic were minutely diminished; as if by spreading the same amount of sound across space, the density became less. In my view the net outcome was positive. Over time I came to realise that this set-up was a little more engaging than the original too.
And this is where things stood until last Sunday (26th March, 2006).
I knew Hugh was working on a novel power supply topology… he described it to me in a café in Brunswick Street in January. Whilst fascinated [honestly], the 42 degree day (that’s 107 deg. F for our Los Estados Unidos amigos) took its toll and I didn’t think much more about it until a couple of weeks ago.
Enter Philip (PT914), our gently spoken and modest, yet clever, American friend. Between public posts and private correspondence I learned that he had tried the regulator topology used in the GK-1 and found it superior to the Super regulator. Additionally, Hugh was sending him a new topology to try out. “Ah ha!”, I thought, “Hugh has prototyped the new power supply… I gotta have me some of that action!” So I e-mailed Hugh, and a few short e-mails later, my rendezvous with the man was arranged.
Fast forward to last weekend…
All else being equal, I would have been in bed when Hugh knocked on the door at 8:30am. Thankfully I was forewarned and had had the opportunity to shower and at least be in a decent state for the arrival.
Entering my living room, and after paying the obligatory “nice house” observations (I’m sure they were sincere Hugh, I’m just taking a little poetic license) Hugh presented a fairly modest looking circuit board, completely stuffed with fairly run-of-the-mill components. We sat down and Hugh proceeded to spend the first little while talking about the power supply circuit with the occasional peppering of other small societal observations. After the walk-through, I opened up my ASP box and disconnected the ALW-based power supply, substituting wire connections for temporary pcb pins allowing easy connection by alligator clips. And then… we went out for breakfast.
Upon returning, we hooked up the power supply and flicked the switch. [Note, all power supply testing was done on one side only, using the other for A-B comparison].
I was not really prepared for what I heard… the sweet sounds of high frequency instability! Clearly a little disappointed, Hugh was about to disconnect when I suggested that we have a listen to some music anyway. I cued up some track or another on my trust slim server and we started listening. From memory it was Eva Cassidy singing “Somewhere Over the Rainbow”, courtesy of our Scandinavian brother-in-arms, Jens. Whilst it was hard to say for certain (blood seeping out our ears and all), it seemed fairly clear to me that something remarkable was happening to the mid range. Below the insistent squeal in the treble was an opening-up of the sound that may have been delightful if not for the oscillatory induced cringe. I thought I must have been mad, but Hugh heard it too. In my mind it was not subtle. We A-B’ed it with the other side and confirmed that, aside from the squeal, the side with the new power supply was simply superior. Still, not much good as it was, so back to the drawing board.
This is where it got fun! Added a resistor across the pass transistor. A little more weight now… not much; but discernable by both of us. The oscillation was perhaps a little less fierce, but still there. It should not have happened given the aggravated circumstances, but I found my soul being drawn toward the sound. In the same way the gaze of middle age men seems to be irresistibly drawn to youthful cleavage, my attention was pulled in to the sound. One thing I had noted to date with the Orions is that they sound very mono when only one side is playing. Now there was this enveloping mass of sound that took on a stereo quality all by itself. Damn I thought! If only the oscillation could be brought under control.
Next step a 470nF polypropylene cap across one of the drive transistors. Power on again… oscillation gone… alright! Now for some music. Johnny Cash’s rendition of U2’s “One” this time. Started off grinning, but within 20 seconds was a tad confused. I looked at Hugh who promptly remarked, “That f*^ked it, didn’t it?” “Yup” I said, “Totally”. Whilst being no worse than the other side, all of the life and drama that had been momentarily intoxicating, was gone.
OK, what next? Lose the capacitor and replace a resistor with a current source, obviously! For that we needed to head to the local electronics store for a new soldering iron and some transistors. Back in the saddle and munching on some minestrone left over from the night before, Hugh soldered to the underside of the board, a couple of transistors and resistor or two. Fired it up and this time he had it! Light, airy, unconfused, seductive, engaging! The oscillation was gone; only beauty beyond what I thought possible from a loudspeaker remained. The only criticism was that the sound had a perception of being less loud at all volumes. Sounds bizarre, but there you have it. “I’ve only got 1.5uF across the output” said Hugh; “I wonder what happens if we add some more capacitance? Got a 100uF electrolytic?”. “Sure I do” and in they went. The result was the same as adding the film capacitor before. Killed the sound dead. It was fortuitous that I had made the ALW super regulators previously. Not compatible with significant down-stream capacitance, I had already removed the 3300uF filter caps from the ASP board. Without this action, we may not have heard what we did… ain’t life grand.
From there Hugh started tweaking some of the key circuit tuning elements… went back to oscillation, stabilised it again. The end result was just like I described above, only without the volume perception issue and with an irresistible Barry White kind of smoothness. It did sacrifice a bit of liveliness and I would have actually preferred a sound ½-way between the pre-tune and post-tune, but I did not have a large enough range of component values at hand (Hugh wanted 33nF, the closest I had was 100nF). I suspect Hugh will hit the sweet point this week. At around 3:00pm we did our final A-B comparison and I’ve got to say, I was astounded. The new power supply made the other side sound like barking mechanical noise. I think the use of “night and day” is lazy slimily. It’s much more like the difference between courtesy and generousity. The former is civilised and makes you feel good, the latter is heart-warming, engaging and makes you feel humbled and embraced simultaneously. The ALW ASP is the former, the Hugh Dean ASP is the latter.
So what’s the take-out of this story?
If you’ve spent several $K on an Orion system, and don’t buy one of Hugh’s new power supplies, you’ve got rocks in your head. I am an individual who finds 90% of satisfaction in the last 10% of met-expectation (if you’ve ever had the last bit of icecream fall out of a cone, you know what I mean). For me, I could not reasonably expect to get that level of upgrade by spending $1000 anywhere else.
And if Hugh can manage to scale this design for power amps, god help my Visa account.
Thankyou Hugh for an enlightening experience. To all other Orion users, stay tuned to AKSA news!
(Note: I have not upgraded my ASP in any other way as yet).
