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What SMPS to replace my linear power supply?

tomchr

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The LJM 12-2 is a discrete Class AB amp. That's a rather different animal than a Class D amp. You need an amp with good PSRR if you want good results with a switching supply.

I've used the Connex SMPS300RE, SMPS300REh, and SMPS800RE with my Modulus amps. I'm not able to measure anything SMPS-related on the output of the amp. The Modulus amps are all Class AB and have a built-in error-correction circuit that makes them very low distortion (think -120 dBc) and rather agnostic to the power supply used.

Tom
 

raindance

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I believe this is the same amp as the CDA series; it just has a preamp stage with variable gain and a much higher input impedance added to it.
 

Valhalla

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why would you want to replace a linear PSU with s SMPS? Recently I replaced a Hypex DLCP DAC SMPS with a lineaer power supply (regulated with less than 2mV ripple) and it sounds a little better to the ear.
 
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Gorgonzola

Gorgonzola

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A bit over a decade ago I constructed a power amp based on an SDS-258 modules from Class D Audio. The kit I purchased included a linear power supply. Presently I'm contemplating replacing that PS with a switching-mode one. The current linear supply puts out +/- 62 VDC.

I would like advice on a proper SMPS to replace the linear.

Incidentally the SDS module is/was Class D Audio's audiophile offering whereas the CDC model testing by Amir is not considered by them to be a good.

My reasons for this swap are essentially two:
  • This amp is a backup amp for my main amp, (Purifi), and others so gets move around fairly often; it's excessively heavy thanks to the large transformer; hence I would like a much lighter SMPS supply,
  • Secondly, more on principle more than practical consideration, I would like a efficient, less power-hungry supply
Of course I don't want the sound of the amp to be adversely affected, though again of course, if the SMPS is appropriate and functioning properly I won't hear a difference.

Here's a pic of my DIY amp -- restrain your laughter regarding the crudeness of my case and assembly;

gi.mpl
MISSION ACCOMPLISHED :D

I have successfully swapped the original linear power supply for an SMPS. Thanks to @tomchr for suggesting the Connexelectronic SMPS800RE.

I installed the SMSP800RE with +/- 60 VDC to duplicate the original linear supply; I selected the +/- 12 VDC secondary supply though I'm not using it. It works great.

I consider my primary objectives, (above), completely satisfied. The unit is much lighter -- in fact lighter than VTV stereo Purifi amp. Granted the lighter weight is largely due to my very light, very amateurish, DIY MDF enclosure. Regarding enclosure, the components would fit in a much smaller case, and I might at some point look for a more elegant ready-made case.

Subjectively the sound is excellent. I would say subjectively as transparent as the Purifi and with comparable bass. The top end is perhaps a tad brighter (?) but this is an attribute of the SDS module, I suspect, not the power supply. The look inside is a good deal cleaner.

smlX_DSCF1530.jpg
 

audio2design

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Looks great!

My cautious side, having seen many a failed AC supply with burn marks (MOVs, FETS, etc.) would say MDF is not the best choice. Fuses, don't provide the protection needed for some types of faults not to become a fire hazard.
 
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Gorgonzola

Gorgonzola

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Looks great!

My cautious side, having seen many a failed AC supply with burn marks (MOVs, FETS, etc.) would say MDF is not the best choice. Fuses, don't provide the protection needed for some types of faults not to become a fire hazard.
Thanks, I appreciate the advice. I would certainly like to put the components in a decent aluminum or steel case, and hope to get around to it.
 

tomchr

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I'm glad it worked out for you.

You can always line the chassis with copper tape or copper mesh. You can pick up the mesh in and arts/crafts store (or so I'm told). Brass mesh would work too. Finer is better. Solder it together in the corners and connect it to ground.

Tom
 

Drossel

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I have done a Holton 1000 with Hypex SMPS 3000 W 2 x 85 v. The Hypex is really bad. Anybody tried the Microaudio SMPS?
 

Waxx

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I've used Meanwell smps's, and seen many others do the same. Many here think they are among the best arround. They are not marketted for audio, they are general purpose but very low noise and very reliable.

I used it to fix an old 100V amp with a broken psu transformer that needed 48V 8A for an organisation with very limited budget. The amp never sounded better they say and about 15 years later it's still in use, with that Meanwell (medical grade) SMPS build in as psu. Don't ask me type numbers it's long ago, i don't remember that.
 

Roland68

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I've used Meanwell smps's, and seen many others do the same. Many here think they are among the best arround. They are not marketted for audio, they are general purpose but very low noise and very reliable.

I used it to fix an old 100V amp with a broken psu transformer that needed 48V 8A for an organisation with very limited budget. The amp never sounded better they say and about 15 years later it's still in use, with that Meanwell (medical grade) SMPS build in as psu. Don't ask me type numbers it's long ago, i don't remember that.
I can only agree with you and it also coincides with my experiences. Especially many of the (open) industrial power supplies are very well suited.
Unfortunately, to my knowledge, Meanwell does not build any power supplies with a +/- dual voltage that are suitable for power amplifiers.
 
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