Interesting Article On Power Supplies

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Freo-1

Interesting Article On Power Supplies
« on: 6 May 2016, 08:16 pm »
This article showed up in ye old Inbox last week:

http://benchmarkmedia.com/blogs/application_notes/152143111-audio-myth-switching-power-supplies-are-noisy?utm_source=Benchmark%27s+Application+Notes&utm_campaign=7445cef5f8-Application_Note_58_5_4_2016&utm_medium=email&utm_term=0_7c8c792ee5-7445cef5f8-34712529

Although one's initial reaction is "yeah, right", none the less, it's hard to argue against the engineering team at Benchmark.  Having owned their DAC-2 for some time, I can attest that it easily has the lowest noise floor of any audio source I've come across.  In fact, using the DAC-2 with a pair of Primare A34.2 amps in mono, along with the A32 preamp (all of which have switching power supplies), has provided a level of playback accuracy that I have not experienced with this hobby. 

I would love to audition the Benchmark amps, as I bet they deliver the goods.   

So, what do folks reckon? 

Panelhead1

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Re: Interesting Article On Power Supplies
« Reply #1 on: 6 May 2016, 08:30 pm »
  I received the article or tech update. There is no doubt they know what they are doing. The results from Benchmark are SOTA.
  The fact that a well designed and implemented switching supply can work well should be no surprise. Had a Linn phono stage 20 years ago with a "brillence" switching supply. Even back then a good switching supply could be built. They have improved a lot since then.

Folsom

Re: Interesting Article On Power Supplies
« Reply #2 on: 6 May 2016, 09:04 pm »
Well given that I've heard them... The sound was good. I'd consider them for a HT but not music however (personally). At their price they're a mix bag. For the size and heat they are perfect for HT, absolutely stellar for form to function. The wattage is high enough to note that it's serious. You can get classD wattage that's higher for a similar price or less. That makes it a hard bargain since I'd only be looking at HT uses. I don't personally feel a big connection to HT and abundance in quality; so a slightly less appealing sound of classD in that price range isn't such a big deal. If anything 2 channel HT is fine for me. Enough about the amps themselves...

Their "beyond the human hearing" noise from their SMPS is in a range that's actually pretty audible by the time it goes through an AB amplifier circuit. You don't hear the frequency, but you hear what it does to amplification. Still it may be pretty low level anyhow.

SMPS's also have no measure for current handling.... well in that regard there is no measurement known to the audio world for the behavior of the current. And no SMPS powered amplifier has yet to thrill me in that realm. The only devices with them that I can approve of have been DAC's.

They also clearly don't care to mention that SMPS's create noise on the mains lines. Theirs may or may not have a form of correction to help with that. (unclear from pictures)

Their video is funny because they have a shielded SMPS vs. unshielded transformer. Also their graph is an undetermined plot, as if it were to show RF it might look different especially if it was shielded and unshielded demonstrations of both. Besides that you can't pick up that much noise on your interconnects because they don't work the same way.

They make it sound like no one has ever made any effort to reduce noise from a transformer (or make it disappear for that matter). That might be true if they were comparing their products to non-audiophile equipment.

Overall I think they're making decent products, but for me you have to walk the walk not just talk the talk. And when my ears agree with the talk, I'll make a note of it when that happens.

Freo-1

Re: Interesting Article On Power Supplies
« Reply #3 on: 6 May 2016, 09:16 pm »
I would say in the case of the DAC-2, Benchmark has indeed walked the walk.   It makes most DAC's sound pretty ordinary. 

The Benchmark DAC driving the Primare/ATC system is easily one of the most musical playback systems I've come across to date. 

*Scotty*

Re: Interesting Article On Power Supplies
« Reply #4 on: 6 May 2016, 10:44 pm »
Switching power supplies certainly produce some HF noise, but that doesn't mean that it can't be dealt with by using a combination filters and regulators. The Stereophile measurements of the DAC 2 document this fact.
Scotty

Folsom

Re: Interesting Article On Power Supplies
« Reply #5 on: 6 May 2016, 11:49 pm »
Switching power supplies certainly produce some HF noise, but that doesn't mean that it can't be dealt with by using a combination filters and regulators. The Stereophile measurements of the DAC 2 document this fact.
Scotty

Well, same can be said for linear really. That is unless you believe it's only possible to mount a toroidal transformer on top of your circuit without protection, dampening, or anything else.
« Last Edit: 7 May 2016, 03:38 am by Folsom »

*Scotty*

Re: Interesting Article On Power Supplies
« Reply #6 on: 7 May 2016, 12:25 am »
At least 60 or 120Hz hum does not produce downward noise inter-modulation distortion by-products the way a poorly designed switching power supply does.
 Benchmark realized two substantial benefits from putting the R&D into the switching power supplies. Number one is a large long term savings in parts costs. Number two is that their power amplifier has all of the benefits of a regulated power supply, without having to design and build a good sounding regulator for the power amp. Sonically speaking, this is a heck of deal and accounts in part for positive reviews their amp has received. As tertiary by-product they also get to save on the cost of shipping their power amps to dealers.
  The Benchmark AHB2 Power Amplifier in rack mount trim has a shipping weight of 17lbs. In contrast, my 110 watt/ch. Superphon DM 220 with a 500watt bifilar wound E core transformer weighs in at 35lbs. and would ship at a weight in excess of 42lbs.. This is over twice the shipping weight AHB2 amplifier, you do the math.
 It is almost enough to make me convert my amp to a switching supply to get the benefits of voltage regulation of the output stage.
Scotty

Folsom

Re: Interesting Article On Power Supplies
« Reply #7 on: 7 May 2016, 03:49 am »
The benefits of a regulated supply can be different depending on application. An AB amp can have some pretty amazing PSRR, negating the benefits of just regulation; but that's a whole other element of design that's an art. Benchmark is able to circumvent that. But regulators are much more useful for reducing noise, barring PSRR issues.

I'd like you to try an SMPS power supply. Your EI core rejects a lot of RF, you might be surprised at the difference in sound. 

G Georgopoulos

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Re: Interesting Article On Power Supplies
« Reply #8 on: 7 May 2016, 04:07 am »
Switching power supplies certainly produce some HF noise, but that doesn't mean that it can't be dealt with by using a combination filters and regulators. The Stereophile measurements of the DAC 2 document this fact.
Scotty

scotty, I salute you man, very good post...
linear regulators are highly inefficient compared to smps's

cheers