Power Supplies

[rollo]

   We have all read about modding ones power supply. It appears the power supplies of most gear is where cost savings have entered the picture.
   We read about Bybees, By pass Caps, Regulators, Caps, voltage regulators, Diodes and the like.
   We rarely hear about the entire power supply. Just bandaides to lower noise. We buy power cords, conditioners, isolation transformers. Which do make a difference.
   If one was to build the all out state of the art power supply what would be the most important aspect left out by the original design, Better trannie, overall design, larger storage caps, superior voltage regulation, all of the above.
   I believe our components are limited due to cost of such in the original design. I would think the trannie makes has  the largest affect.  Just do not know.
   So if one is building the ultimate power supply what do you think makes it that way ?


charles

[_Scotty_]

From my own experience there is no ultimate universal power supply or one size fits all applications.
When designing a supply for small signal devices such as preamps the transformer needs to over-sized from what might be the minimum size necessary to meet the current demands of the circuit to the point that you can't hear any improvement from going to the next larger size.
 In the case of my preamplifier it took a 225 watt toroid transformer before the point of diminishing returns set in. You could hear the difference between a 150watt and the 225watt transformer. The circuit could have been run on a 30va transformer but it would have been badly crippled. 
 When we changed the transformer in the preamp from the  bare minimum necessary to power the circuit to the 225watt toroid we lowered the power supply's dynamic impedance. The dynamic impedance of the power supply is a critical factor that can limit how well the circuit can track the music waveform.
 The dynamic impedance of the power supply is influenced by many things, a few of them are how big the transformer is, how low the power supply's storage capacitors ESR is at frequencies near 1 MHz, and the inductance of the wiring or circuit traces in the power supply.  All of these things influence the dynamic impedance of the power supply. The size of the storage capacitors used in the power supply is also important as is the total amount of capacitance for energy storage. Once again the capacitor bank should sized so that the point of diminishing returns has been reached.
 Again, using my preamp's point of diminishing returns as an example, a 10,000 mfd JENSEN 4pole electrolytic capacitor per rail was pretty much the point of overkill. The JENSEN 4 pole electrolytic capacitor has a very low ESR clear out to 1MHz which is why it is my go to cap of choice when it comes to designing any power supply used for SS gear. I would also look hard at them for use in tube power supplies.
 To put the size of the power supply used in my preamp into perspective the average well designed 60 watt per channel power amp will have about 10,000 mfd of storage capacitance per rail and a 225 watt transformer. A bean counter would nix the idea of using a power supply this big in a pre-amplifier straight away.
 If you can look inside a piece of gear like a DAC or a Phono stage or a preamp and you see an itty bitty power transformer you are probably looking at a performance choke point. If you are told that the size of the power supply you see was based on listening tests and they couldn't hear any improvement from a larger power supply this is a red-flag. What they have told you is that the circuit has some serious limitations beyond just the size of the power supply.
 At this point I would look at another brand of equipment.
Many times you can weed out products based on the size of the chassis alone. If a big transformer could not possibly fit in the box you are looking at then you can bet there isn't one in there.
That being said my comments are directed to those components that list a convention linear power supply as part of their make-up. Products with switching power supplies will just have to be listened to and a judgment made as to their sonic qualities.
Scotty

 

[satfrat]

Unlike Scotty, I don't have the technical qualifications to contribute in an intelligent conversation on the topic of power supply builds but I have tried a few aftermarket power supplies and I've been really happy with Paul Hynes. For those "in the know", I take heart knowing that individuals like Wayne Waananen of Bolder Cable and Steve Nugent of Empirical think enough of Hynes regulators to use them in their products.  

In the realm of power, I'm a firm believer and user of BPT balanced power, PI Audio UberBuss parallel filter & a house full of parallel filter wallwarts, many uses of my 27 Bybees. And of course a Paul Hynes SR3-12 power supply of my Off-Ramp 3 USB transport (now built-in with the new Off-Ramp 5).

As saturated as my system seems to be as everything in my A/V system runs from a dedicated circuit thru the UberBuss and BPT BP2.5 with large Bybees both before and after the transformer, the one thing my system doesn't lack is dynamics and sound stage depth(tons of both).   

System bandaides ain't half bad IMHO and are basically necessary in our world of household AC line grunge, again IMHO.  

Cheers,
Robin

[Barry (NJ)]

Hey Robin, Power Supplies != Power Conditioners

[_Scotty_]

I'd like to say that for my money every piece of audio gear made needs some kind AC power filtering ahead of it regardless of what the manufacturers of said gear have to say on the subject. It has been my experience so far that a power supply designed for very low dynamic impedance does help to filter out some power-line noise.
 But, judging by the positive effect that putting a Felix filter had on the sound of the system, the amount noise removed by the filter caps and the shunt regulation of the circuit was inadequate.
 Unfortunately AC power filtering has no effect on the components dynamic power supply impedance, this is determined the power supply design. It can't substitute for an undersized transformer and inadequate energy storage due to a lack of capacitance.
AC power filtering just helps you get closer to what you might have had in a perfect world with clean AC power.

[Response Audio]

The power supply is an often overlooked part of any component, mostly due to either budget restraints or simPly the lack of knowledge on how to design a first rate power supply.
I won't get into what makes for the ultimate power supply as DIY'ers and manufacturers alike all have their personal opinions.

I will say Scotty is right on with what he said but there is also a lot more to it. Even with the proper choice of quality parts, knowing what to do with them is equally important. Propably more so. There are many things that can ruin an otherwise good design such as an impropeely implemented grounding scheme.

If you are building your own power supply, take the time to do some research to know just what to do with all those expensive parts you spent your hard earned money on. It's not too hard to build a very good power supply if you know what you're doing but it's just as easy to completely waste your time and money if you don't.

[_Scotty_]

Bill I was trying to follow the KISS rule with my simplistic treatment of power supplies.
I didn't want to touch on the complexities that can be encountered when it comes to setting up the ground in a chassis. Nightmares are made of those.
 I think a lot of the inadequacies we see in power supplies can be attributed to a lack of budget or the need to hit a price-point with given product.
 I guess my main gripe comes from claims by manufacturers about their product being "cost no object the best there is" when it clearly is not a cost no object design and corners were cut starting with the power supply and ending who knows where. 
 Now I've gone off topic and on a rant against outrageous marketing claims,I must be getting old.
Have a good weekend everybody I'm going to bed.
Scotty

[satfrat]

No grips myself. I have no doubts there are components built with superior power supplies, like Bill's high end Purity preamps. But +/-20K range is way out of my grasp for such a piece of ultra clean gear. I bow to Woodsyi in that department. 

For what I have, I'm in full agreement with Scotty. There's nothing in my system that would be better off without what I already have in place but instead going straight to the wall socket. At least to my ears that is, ymmv.

Cheers,
Robin

[BobM]

From my experience after tweaking many components over the years I have found the following:

- inexpensive components can usually be improved by tweaking the power supply - replacing diodes with Shottky type, increased capacitance, added conditioning, full replacement with something more robust, etc.

- expensive components seem to be overbuilt in general and I am reluctant to play with their circuit and component choices. They seem to have done a good job with the power supply itself, already incorporating most of what I can do myself to a power supply. In fact, they especially DO NOT seem to benefit from conditioning, and sometimes sound worse if power conditioning is applied.

I guess the bottom line is sometimes you get what you pay for, and good design is good design.

[Triode Pete]

The power supply is an often overlooked part of any component, mostly due to either budget restraints or simPly the lack of knowledge on how to design a first rate power supply.
I won't get into what makes for the ultimate power supply as DIY'ers and manufacturers alike all have their personal opinions.

I will say Scotty is right on with what he said but there is also a lot more to it. Even with the proper choice of quality parts, knowing what to do with them is equally important. Propably more so. There are many things that can ruin an otherwise good design such as an impropeely implemented grounding scheme.

If you are building your own power supply, take the time to do some research to know just what to do with all those expensive parts you spent your hard earned money on. It's not too hard to build a very good power supply if you know what you're doing but it's just as easy to completely waste your time and money if you don't.

Bill,
You are exactly correct! As I always say, the quality of the design & build is ALWAYS more important than the quality of the parts... now when you get the design & build right, then the parts matter...

Also, many of the power supply designers can learn a lot from the high end radio designers of yesteryear... the "lost art" of proper grounding techniques & component layout can be found in those vintage radio sets... check out this E.H. Scott (No relation to the H.H. Scott of the 50's & 60's) hi-end radio...



I've seen quite a few of the internals from old, hi-end radios and the layout & craftsmanship is amazing. Some actually use a grounding "bus-bar" through the power supply... really neat!

Pete

[Response Audio]

First things first.... That is a very cool picture!

Another thing that sets good designs apart from the bad is the overall picture. I have seen some very good circuit designs but associated with poor power supplies. Then you will see some exceptional power supply designs tied to inferior circuits. I hate to use cliches but an overall design is only as good as its weakest link. If you're not going to install the same principles to the complete design of a product, why bother.

We spent as much time developing the Purity power supplies as we did the analog circuit they are responsible for.  They do, after all, go hand in hand.

Upgrades are a whole different story. I have seen many products come through my benches that were previously 'upgraded' by someone else. What is most apparent from these pieces is that there are a lot of people out there that don't realize you cannot simply replace power supply components and expect everything to still maintain the same specs. Replacing capacitors with different quality or types will very often change voltages (at the very least). This is due to the differences in the DCR of various types of caps. If you increase the capacitance in a filter bank, you will very like change the voltage(s) that bank provides.

My recommendation is to not get too involved with upgrading a product, especially the power supply, if you do not understands the potential effects it can have have on how that circuit will perform afterwards or not kowing how to accommodate for those changes.

This is why consumer modified products (and even some 'professionally' modified products) have poor resale values. A potential buyer has no way of knowing if the upgrade was done by someone who knew how to do it properly and maintain the required specs within the circuits.

I am not making any judgements on any particular person or company. This is simply a general statement based on my past 15 years of modification and design work in the industry.

[rollo]

   Good advice Bill and well taken. Not as simple as one thinks.



charles

[tmazz]

   Good advice Bill and well taken. Not as simple as one thinks.



charles

When you get to this level of technology nothing is ever as simple as it looks.

[steve]

As far as I am concerned, it is all about the sound. Different designs require different power supplies.

Cheers.

[djbnh]

As far as I am concerned, it is all about the sound. Different designs require different power supplies.

Cheers.

I find this comment represents my thoughts, too. For example, I have a pre that is battery powered, and the lack of noise plus product performance does it in spades for me.