External power supplies

April 18, 2021
 by Paul McGowan

On the periphery of exotic upgrades is the external power supply. Sometimes this supply is bigger and more powerful than what’s standard inside products, but more often than not it’s simply the only means of powering a product. A wall wart is a great example.

In my experience, the first use of an external power supply came from PS Audio, nearly 50 years ago (though likely others did it too).

When Stan and I were working on building new products, Stan had discovered the benefits of an oversized power supply: more slam, openness, greater solidity in the bottom end, and far better transparency. The bigger the transformer the better the sound.

At the time, we only made line-level products like preamps and control centers. These types of products were always housed in 1U, 2U, or sometimes a 3U chassis (a “U” is short for Rack Unit and is a standard for rack mounting at 1.75″ tall). Our 2U chassis height could never accommodate a monster power transformer so we did what anyone trying to shoehorn in a 5-pound hunk into a one-pound bag: we put it in a new and larger housing. We called it the HCPS for High Current Power Supply.

The benefits from externalizing the power transformer were many: better sound, lower hum, and the ability for our customers to choose what level of performance they could afford. The last one we produced was back in the PCA2 preamp days of the 2000s, as well as a smattering in the Gain Cell line of products. It was (and is) a cool idea but, alas, limited in its appeal.

Seems the trend today is less rather than more.

Big external boxes powering high-end audio products are rare and often viewed more as exotic than standard.

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24 comments on “External power supplies”

  1. I see a huge trend of replacing tiny small wall-wart SMPSs by big LPSs feeding DACs, network switches and hubs, DDCs and music servers and music streamers (Roon Nucleus, Intel NUCs) with standardized voltages (5V, 12 V, 19 V). Isn’t it strange that home audio lacks standards for DC voltage unlike seen for PCs? And there are indeed huge external boxes (see: https://stromtank.com/s5000hp/ ) solving the problem of lacking DC-standards by generating clean AC from a tower of modern batteries.

    1. Annnnd that would be me. 😉

      I’ve got a couple LPS’s. I have 6 individual pieces of equipment operating at the same time for my ultimate headphone rig. 2 of which are LPS’s.

      Guilty as charged dittly arged.

      Sorry. That was my Ned Flanders coming out.

    2. Seems to me it’s going the other direction: SMPS getting good enough to replace LPS. I don’t know if it’s related to continued work on Class D gear, but in my diy projects, when Nelson Pass says the SMPS he recommends is “fine” for a line-level component and even a low-power amp, I pay attention. Which is not, obviously, to say he puts then on Pass or First Watt gear. But I was a little surprised the Stellar Phono Stage didn’t have a separate LPS, given an MC-capable preamp’s sensitivity to nearby noise-producing circuits. Or does it?

  2. Spot-on, Paul!
    Over the years I have also found out first hand the benefits,
    nay the importance, of an over-sized power supply.

    Unfortunately, these days the majority of music lovers want
    everything in 3 boxes (Back to the ‘3 in 1’ of the 60’s & 70’s)
    But now it’s the streamer, transport, DAC, DSP/DIRAC &
    preamp in one box & the power amps & loudspeaker drivers in the other 2.

    Many will give up the accuracy & precision of their favourite
    reproduced music from a high-end audio rig for convenience,
    a minimalist ‘look’ & size (allowing more real estate in their living
    rooms) & less arguments with ‘she who must be obeyed’.

    Progress?
    I think not.

  3. As with all things, there’s a tradeoff. Large external LPS’s can produce a fairly large electromagnetic field, which if placed in close proximity of other devices or cabling, can be more of an issue than a well designed SMPS. One size doesn’t fit all.

  4. I have no issues with size or extra boxes as long as a performance increase is realized. If a pair is to be “stacked” then I would expect care would be taken in the design to contain EMF’s and other radiating sources of noise.

  5. Yes it seems manufacturers today live with the fact that their customers continue their job by throwing money on external supplies of other manufacturers to further improve.

    Maybe the reason is, that original manufacturers prefer to build to a price point and sell trendy one-box units with the story that it doesn’t matter anymore that much nowadays if you do it good enough.

    On the one hand it seems, manufacturers indeed get really far with one box designs and normal sized solutions, on the other hand some implications might arise as recently as the unit is in charge to integrate with evolving demands in the home of the customer (connecting subs or power amps directly to front end gear or recognizing radiation sensitivities in connection with cabling or other gear).

    What remains a mystery to me is why especially phono amps at a certain price point are still fitted with internal supplies. There (the units usually laced close to the turntable and other gear) an external one should have most benefits.

    It would be furthermore very interesting what happened (I know it’s not realistic) if PSA e.g. would have offered a DS DAC with the option of having an integrated unit with psu inside or the same chassis without the whole psu part with connectors to attach an external one. Probably the DS would then be 500$ cheaper…exactly the 500$ one needs to connect a multi outlet high end external supply. I guess the sonic result would have been extremely favorable and the money spent not much more.
    How would customers have decided?

    The decision about power supplies (their size and elaboration, also external/internal decision) seems to be an extreme cost factor. What I observe is, that many talk a lot about the importance and certainly know about it, but only few really act more than all others do. I remember Accuphase building large units into their products since the early days, Naim and the less known Phonosophie are certainly early extreme implementers, I remember Gryphon as always having had that focus (a different cost focus certainly) and probably several others also in the US. Several other manufacturers focused especially on external supplies early and continued to do so (even at a very competitive price point, Octave tube pre and phono amps or Schaefer (the Emmitters and phono stages come into my mind), again probably various in the US, too. To be honest, as good as PSA components are, at least within the portfolio I witnessed during the last half decade or longer, units didn’t surprise with noticeably large nor exterior psi solutions compared to the competition, not at all. Seems this is compensated by appropriately creative designs (as again many claim to have, but PSA also seems to implement successfully). I perceive PSA in its today’s approach rather as lifestyle/cost/highest audio quality focused than focused on the principle of using technically most optimal solutions.

  6. Both of my last two preamplifiers had external supplies the ARC SP11 and the Manley Labs Steelhead. It makes perfect sense keeping the mains a/c well away from any sensitive signal circuitry. The umbilical feed obviously must be long enough to give a suitable separational distance without the multicore being too unwieldy to handle, a compromise I suspect.
    In my opinion its certainly worth the extra expense.

  7. Good morning Jazznut,
    Perhaps you might reconsider “Lifestyle”. We agree on “cost/highest audio quality focused…”. PS Audio a “lifestyle” company? Just because they produce high-value, real world priced components (for high-end anyway)? We can agree that PS is not a cost-no-object assault on high-end. I think my system is high-end. But, $40k on a 4 foot high rack with 9 boxes (3 are PS Audio) + 2 Maggies and 2 Rels is quite enough! I hope Paul’s guys are working on a 1-box CD player with DAC, because I feel no need to exchange my excellent 1 box player for 2. Does that mean my system is “lifestyle”?

    Off-topic: We have not heard much from Soundmind in awhile. I miss his earnest, thoughtful white papers. If you have turned your attention to other matters in life, I completely understand. Just hope you are okay. You are valued.

    – Jeffrey

    1. No JAS, good to clarify, that was not what I meant, I see lifestyle clearly not as a primary focus of PSA and I see PSA as a true high end supplier.

      What I meant was, that I see PSA making the one or other compromise (as many do) … for cost reasons and/or for “lifestyle” reasons (e.g. in terms of not separating power supplies up to probably a very high price level compared to some others). They certainly do it for good reason and with success and we all be edit from this cost/performance approach (I own a DS, too).

      There are some companies having the cost no object mindset, some having the “technical principle no object” approach making compromises in lifestyle design and PSA in my perception has a kind of “beat optimal well known but expensive technical principles with innovative circuit design” (to achieve their cost/performance ratio) approach. Due to the success this usually works, but it also hits some limits sometimes compared to other approaches at similar price points imo.

    2. Yes, many of us are in that vulnerable age group with Covid 19. Hopefully Soundmind is in good health and just taking a break from this thread. Or maybe he is abstaining until they get the type size and font issue straightened out. Can’t blame him for that. I’ve certainly been less inclined to strain my eyes. lol

  8. I have noticed that many hi-end companies ( VAC, VTL, ARC, CH Precision,etc.) have their top-of-the-line products built with very substantial separate power supplies. Along with reducing noise in the actual unit ( e.g. preamp, phono premap, or power amp ) it actually helps with keeping the weight of any single box to reasonable limits. I do not own any such two box units, however, I have come to wish that it did have at least one two box unit. My power amp weighs in at 220 lbs. You can not imagine how much “fun” it s to move the thing around.

  9. The power supply inside the unit works just fine. The next thing they will do is have the heat sinks and output devices separate from the unit. Why not have 5 or 6 separate devices that make up a preamplifier or amplifier? Why stop at the power supply?

    1. Advanced electronics such as the Spectral DMA-500 Monaural Reference power amplifier feature independent power supplies for each output transistor.

  10. In addition to separate power supplies, the ultra high end trend in Europe seems to be to have separate chassis for each channel, hence four boxes.

    1. Not very sure about all the corresponding US offers, but I remember e.g. the „smallest“ preamp from Spectral at the time (the DMC 12, going for under 2k used nowadays) already had a separate power supply, e.g. Manley have, too, in a 6k range as far as I remember. Gryphon might indeed have been one of the few (I remember my first separate preamp Elektra) offering a double mono/separate supply 4 box design (partly the separate channel chassis were physically connected to two units). Well, integrateds of any kind were always less costly.

      Also not sure who really started the insane current trend to use separate power supplies for each small part of a DAC’s surrounding (streamer, USB/I2S interface, galvanic isolation device, partly the DAC itself, as well as all the network components like Router, switches etc.), but there are several US companies quite active in this regard 😉

      Extremes taken aside, what’s well comprehensible is, that a psu inside the same housing as the electronics of sensible components can be bettered (even if it may sound good enough already). But for sure the sound resulting from a sophisticated detail design is more important, at least up to a certain level when every basic improvement has big influence.

  11. Mark Levinson introduced the LNP-2 preamplifier in 1973 featuring a discrete power supply. The LNP-2 redefined the concept of high-end audio electronics established by Saul Marantz in the 1960s with the Model 7 preamp & Model 9 monaural power amplifier.

  12. A cautionary note. Do not combine the pictures for yesterday’s and today’s Pauls’s Posts. Pouring maple syrup into an external power supply will not sweeten the sound and will likely result in popped circuit breakers and possibly fire.

        1. Given Paul’s commendable preference for U. S. sourced produce, he gets his from a farm on Three Mile Island, Pennsylvania. Another source of the plants can be imported from Fukushima Prefecture, Japan, although the air freight required to maintain freshness adds considerably to the cost.

  13. To date, no one has built a light-weight small power supply that is quiet, electrically or in terms of RF. So we see all sorts of circuit topologies that mitigate the noise by employing isolation, shielding, or both. Mitigation is not elimination. An external power supply can come as close to elimination as is possible.

    The best of all possible worlds is an external battery. Failing that, an external power supply fed by a PS Audio regenerator that is connected to a dedicated 30-amp line with a true earth ground would be the next best thing. While I had that in my laboratory, it has no commercial viability.

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