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Porkbuns69

Is this a 24v DC switching power supply?

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Posted (edited)

If it was intended for general readers you would not have needed to quote anyone :D

 

Edit: what is that now, 8 pointless posts?

 

Edit: also, the switching aspect had been covered by Andy's post (post 3)

Edited by Muon N'

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19 hours ago, andyr said:

 

You are correct, P69.  So, yes, you could replace it with a 24v linear PSU.  If you're in Melbourne, I could bring over a 24v DC Sbooster linear PSU for you to try-before-you-buy.

 

PM me if you're interested.

 

Andy

 

Thanks Andy.  Got other system priorities atm, will drop a line when i get to the point of addressing this.

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2 hours ago, Porkbuns69 said:

Thanks Andy.  Got other system priorities atm, will drop a line when i get to the point of addressing this.

 

NP, P69.  :thumb:

 

Andy

 

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10 hours ago, MLXXX said:

 

The issue of concern for the OP was the "topology" of the conversion to 24V DC.

 

It is audiophile lore that a power supply that uses the modern technique of switching is bad  and that "old-fashioned" linear is good. A reason advanced for that view is possible Electromagnetic Interference (EMI) from a switching power supply.

 

 

At the risk of adding to the # of 'pointless posts', I will state what a group of us heard, a few years ago, when I was experimenting with different power supplies for my then new 'Number9' TT motor speed controller.

 

I do regard SMPSes as generally inferior to a good linear PS.  So, given the Number9 was supplied with a 48v SMPS, that day we tried out 5 different PS setups for the Number9:

  1. the supplied 48v Meanwell SMPS
  2. a 48v SLA supply - consisting of 2 strings of 4x 12v SLAs in series (to halve ESR), with a 40uF film cap across the outputs.
  3. a 48v linear PS that I built (an AKSA design).
  4. #3 plus an isolating transformer + hash filter between the linear PS and the wall.
  5. #1 plus an isolating transformer + hash filter between the Meanwell and the wall.

Now:

  • it's possible the linear PS I built was not a very good one - so, say, an Sbooster would've performed much better.  (Unfortunately, though, Sbooster don't make a 48v version.  :( )
  • it's also possible that, say, #2 would've performed better, had I used a much larger bank of caps across the outputs ... or more parallel strings of SLAs (which would've been costly!).

But the result of the experiment was that #5 sounded the best!  What that says to me is that SMPSes (well, Meanwells, anyway) inject hash back into the mains ... to 'infect' other components in your music system.  The hash filter stops this.

 

So a SMPS isn't necessarily inferior to a linear PS - but you need to have a hash filter (and probably an isotran) between it and the wall socket, for best sound.

 

Andy

 

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Interesting, I would have expected the SLA to perform best. It is, in some regards, an ideal power source - no noise, no ripple, very low ESR. A 20Ah battery or larger will deliver peak currents of several hundred amps. In fact, those batteries can deliver currents that would make the wiring inside power bricks melt. The only problem with a battery is that you have to charge it, and while you're charging it you can't use it. Also, you need a good charger to maximise the battery lifetime.

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1 hour ago, Steffen said:

Interesting, I would have expected the SLA to perform best. It is, in some regards, an ideal power source - no noise, no ripple, very low ESR. A 20Ah battery or larger will deliver peak currents of several hundred amps. In fact, those batteries can deliver currents that would make the wiring inside power bricks melt. The only problem with a battery is that you have to charge it, and while you're charging it you can't use it. Also, you need a good charger to maximise the battery lifetime.

 

Correct, Steffen - that was my expectation, too.  :)  Although I wasn't using 20AH batteries.  The 8x 2.2AH batteries I was using cost me about $280 - so I shudder to think of what 8x 20AH SLAs would've cost!  (I needed 4 to get 48v and 2 strings in parallel reduces the Zout of the SLA supply - which is important.)

 

Andy

 

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3 hours ago, andyr said:

So a SMPS isn't necessarily inferior to a linear PS - but you need to have a hash filter (and probably an isotran) between it and the wall socket, for best sound.

I'd insert the word "may". You may need to have a hash filter ...

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