Meanwell Single, Bipolar and Triple Output Switching Power Supplies for Audio Projects

Construction information for DIY projects, including the MS Mid Side Matrix, Elliptic Equalizer, Mastering Console, Phono Transfer System, Insert Switcher and the Dual Class-A Amplifier. You can post your baby pictures here.
dtcicero
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Re: Meanwell Single, Bipolar and Triple Output Switching Power Supplies for Audio Projects

Post by dtcicero » Tue Apr 03, 2018 9:25 pm

I'm interested in using the GP25A so great to see this info. I checked with Meanwell and the GP25A switching frequency is 65kHz. I also found the GP25A does not perform well unless the +15V output is loaded to at least 100mA. I think your tests showed a 50mA load on the +15V output?

Thanks,
Dave

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mediatechnology
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Re: Meanwell Single, Bipolar and Triple Output Switching Power Supplies for Audio Projects

Post by mediatechnology » Wed Apr 04, 2018 2:53 pm

dtcicero wrote:
Tue Apr 03, 2018 9:25 pm
I'm interested in using the GP25A so great to see this info. I checked with Meanwell and the GP25A switching frequency is 65kHz. I also found the GP25A does not perform well unless the +15V output is loaded to at least 100mA. I think your tests showed a 50mA load on the +15V output?

Thanks,
Dave
Thanks for posting Dave!

I just rechecked the GP25A under a heavier load and its bad regardless.

+15V @ 320 mA ripple is about 120 mV p-p and a combination of HF fast rise time spikes and LF ripple.
-15V was loaded in 160 mA, 5V loaded in 500 mA.
The -15V was relatively quiet but the 5V also had about 120 mV p-p ripple similar to the +15V.

(EDIT: Updated the measurements above to reflect that the 'scope probe was in X10 mode. I almost never use X10 but had been working on a power amp and had it switched on.)

I've been using the TDK open frame a lot lately and am very pleased with it. viewtopic.php?f=7&t=945
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Re: Meanwell Single, Bipolar and Triple Output Switching Power Supplies for Audio Projects

Post by mediatechnology » Wed Apr 04, 2018 4:52 pm

This is the GP25A +15V ripple loaded in about 320 mA. The peak-to-peak value is about 150 mV.
The 5V rail, loaded in 500 mA looks about as bad.
Loading or unloading the -15V and 5V rail doesn't affect the +15V ripple significantly.

Image
Meanwell GP25A14E-R1B Ripple

None of the other Meanwell bipolar supplies have this level of ripple.
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dtcicero
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Re: Meanwell Single, Bipolar and Triple Output Switching Power Supplies for Audio Projects

Post by dtcicero » Thu Apr 05, 2018 5:54 am

Thanks for running the tests again! It's a shame the performance is not at least equal to what it's meant to replace. I really like the P25A/GP25A form factor, and no worries with UL or mains.

Dave

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Meanwell RS-25-48 48V 0.57A Phantom Supply

Post by mediatechnology » Fri Apr 20, 2018 1:05 pm

The Meanwell RS-25-48 48V (adjustable) 0.57A switcher, when used with a simple RC post-filter, is suitable for phantom power.

Mouser Product Page: https://www.mouser.com/productdetail/me ... xiXg%3D%3D
Meanwell PS-25-48 Datasheet http://meanwellusa.com/productPdf.aspx?i=392#1

Image
Meanwell RS-25-48 48V 0,57A switching power supply.

When unloaded the output has a large sawtooth ripple around 1 kHz.
There is FM spread-spectrum EMI-reduction evident.
The next three frames show audio "in-band" ripple.

Image
Meanwell RS-25-48 48V supply unloaded ripple.
5 mV per vertical division, 1 ms horizontal.


When loaded in 24 mA the output is considerably quieter.

Image
Meanwell RS-25-48 48V supply ripple with 24 mA load.
5 mV per vertical division, 1 ms horizontal.


A simple 47Ω 22µF R-C post-filter lowers the in-band ripple significantly.

Image
Meanwell RS-25-48 48V supply ripple with with 47Ω/22µF post-filter and 24 mA load.
5 mV per vertical division, 1 ms horizontal.


With a faster 'scope sweep rate we can see out-of-band spikes at significantly higher amplitude near the 100 kHz switching frequency.

Image
Meanwell RS-25-48 48V supply ripple near the switching frequency with with 47Ω/22µF post-filter and 24 mA load.
20 mV per vertical division, 10 µs horizontal.


I haven't checked the ripple performance at higher currents.
My interest is primarily for builders making simple 1U and 3U rack projects and not powering entire consoles or big 500-series frames.

The lightly-loaded post-filtered in-band ripple of the RS-25-48 is low enough for phantom use and, in application, appears in common mode.

The out-of-band ripple might be improved with an inductive filter but the levels seen here are typical for any switcher.
When used in an actual preamp I doubt its high enough to be a problem.
emrr wrote:
Thu Mar 29, 2018 5:47 pm
I've used a bunch of the Meanwell RS-25-48 for phantom, with an RC filter after it. Not been a problem that I've detected. They are adjustable over a small range, so you can land voltage at a best spot for the range of load expected.
So there you have it folks.
The cigarette pack size Meanwell RS-25-48 seems to fit the bill for a $10 phantom supply.
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JR.
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Re: Meanwell Single, Bipolar and Triple Output Switching Power Supplies for Audio Projects

Post by JR. » Sat Apr 21, 2018 8:54 am

Thinking some more about a simple MOSFET pass element configured as a ripple filter I wonder how the tradeoffs or pros and cons weigh out?

Pros
1- potentially very effective noise filter
2- relatively simple, depending on how fancy one gets
3-efficiency or loss, "could" be less than passive filter
4- low output impedance
con(s)
1- complexity... simple passive filter is "simple" (KISS)
2- will cost more than passive
3-slightly higher output impedance?
4-a dynamic ripple filter would take time to adapt to changing load, so could momentarily allow ripple after a load step.

An optimal design could be self regulating, sensing for ripple and minimizing that, instead of regulating to a hard specific voltage. Of course how clever this gets adds complexity and output voltage could shift with load, albeit slowly.

JR
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Re: Meanwell Single, Bipolar and Triple Output Switching Power Supplies for Audio Projects

Post by mediatechnology » Sat Apr 21, 2018 2:05 pm

I think TI makes one.

I also have design Idea Ripple Eater that was published recently.
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Re: Meanwell Single, Bipolar and Triple Output Switching Power Supplies for Audio Projects

Post by mediatechnology » Tue Apr 24, 2018 12:20 pm

The TI ripple eater regulators I was thinking about are the TPS7AXX-series:

TPS7A47 Positive: http://www.ti.com/product/TPS7A47
TPS7A33 Negative: http://www.ti.com/product/TPS7A33
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Re: Meanwell Single, Bipolar and Triple Output Switching Power Supplies for Audio Projects

Post by JR. » Wed Apr 25, 2018 8:56 am

Nice, I was thinking of automatically setting the voltage based on ripple, but if you have the budget a few hundred mV is no big deal.

JR
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Re: Meanwell Single, Bipolar and Triple Output Switching Power Supplies for Audio Projects

Post by mediatechnology » Wed Apr 25, 2018 11:43 am

wereoflu used the TPA7AXX-series in his minimixer which is where I found it: viewtopic.php?f=6&t=882#p10291

There's another ripple eater I recall from a Design Idea.
I'll dig, scan and post.

My goal is to have something that plugs in and works without any additional filtering.
Most of the Meanwell and TDK models I tested are great.
The simple RC required for the 24V and 48V supplies aren't a deal-breaker.
In the case of the 24V for powering relays external filtering may not be needed at all.
I haven't tried the 24V yet.
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