SMPS for a class A Jean Hiraga 30w

[vishalk]

Hi All

I'm planning on building the Jean Hiraga Super 30w amplifier. Has anyone here successfully used a SMPS power supply on a Class A amplifier?

RS Pro 960W Embedded Switch Mode Power Supply SMPS, 40A, 24V dc | eBay

I was thinking of buying this and trying it, if anyone has some good advice please throw it my way!

Thanks

Vish

 

[Osvaldo de Banfield]

Since about 15 years ago I'm using a DIY SMPS with class AB TDA2006 and TDA2003, and being class A much less PSU exigent, I can't see any inconvenience.

 

[Osvaldo de Banfield]

Look at the aluminium box. This is my DIY SMPS. UC3842 + STPS7N60 + BYW98 * 3, TL431 + PC817. The SMPS gives ±14V and 12V more or less well regulated.

Once I had only 30VAC (Nominal 220VAC) in the mains, once the SMPS started up, then it continued working down to 30VAC. Believe it or not, but I saw it.

 

[scottjoplin]

That's wild Osvaldo, I thought building your own smps was a "black art" haha

 

[Osvaldo de Banfield]

Not necessarily. Reading the Marty Brown and the Abraham Pressman's books was all I need to build this old fashioned SMPS. Plus some "copy and paste", for example, no one of the authors sais how to design the clamp in the primary of the fly back transformer. Ergo, I took the values from dozens of SMPS's I repaired (CRT monitors and TVS, notebook chargers, etc,) then I got an approximate value, and use it (Diode, capacitor and resistor). Hurra, it worked from several years. Not to mention, that when the the SMPS still haven't its box, and the PCB was open at the air, a drop of water-based wall pain drop in the SMPS, just in the MOSFET insulator to the grounded heat sink...Some few sparks, but the SMPS survived OK.

 

[scottjoplin]

Thanks, I'm inspired by you, I will have to read and learn.......

 

[Osvaldo de Banfield]

As only a suggestion, start with a simple project. My first was only a 220AC to 12VDC 3A converter. It is very easy. Check and take note of the difficulties encountered, and learn from them. Once the simple one is at your satisfaction, and if and only if is at your satisfaction, then start a new more complicated one. But do not start from a ±12V, plus a 5V and 250V DC.

I learned lots in the internet, there is much good info, buy you must filter it yourself.

To see how your mind can fly, take a reading at this:

diytube.com • View topic - My "Tube SEPIC II" project

A SMPS made of ... TUBES!!!

 

[Gusser]

I run two 24v 15a switchers on my three channel Elliot 20W Class A for +/-24v. Open PC board type to boot!

No noise problems encountered.

 

[bwaslo]

I use SMPS on my class A's. A disadvantage of SMPS for audio is that when the load is low, many stock designs go into a very noisy discontinuous mode with irregularities even in the audio band. But with Class A there is never a low load (one of the few advantages of class A's poor efficiency) so the SMPS operates at a rather continuous load current so any noise is at very high frequencies and at audio frequencies the supply is tightly regulated.

 

[xrk971]

I tried my Pass M2 (Class A 25w/ch +/- 24v rails and 1.25amp bias current) on a couple of 24v 5amp SMPS bricks designed for LED lighting. They were surprisingly quiet (much quieter than my linear supply) and easy to connect, plus lightweight, cheap, sounds great, and now I am not seeing any reason to go old school heavy iron/copper toroidal trafos anymore.

http://www.diyaudio.com/forums/power-supplies/306411-strange-forest-noise-linear-psu.html

Here is my FFT for 8v rms into 8ohms with the $17 bricks (x2):

This is what I used, looks like price went up to $19ea now:
https://www.amazon.com/SUPERNIGHT-100-240V-5-5x2-1mm-Converter-Adapter/dp/B00LUIKY4S/

 

[vishalk]

I just read though your thread, man how easy was it that you just bought two simple 24v 5amp SMPS and your amp works with no issues?

I mean that's a whole lot easier then making a complete old skool power supply (and much cheaper!)

So i take it you can pump the volume and they can handle the loads? Do they get hot?

I tried my Pass M2 (Class A 25w/ch +/- 24v rails and 1.25amp bias current) on a couple of 24v 5amp SMPS bricks designed for LED lighting. They were surprisingly quiet (much quieter than my linear supply) and easy to connect, plus lightweight, cheap, sounds great, and now I am not seeing any reason to go old school heavy iron/copper toroidal trafos anymore.

http://www.diyaudio.com/forums/power-supplies/306411-strange-forest-noise-linear-psu.html

Here is my FFT for 8v rms into 8ohms with the $17 bricks (x2):

This is what I used, looks like price went up to $19ea now:
https://www.amazon.com/SUPERNIGHT-100-240V-5-5x2-1mm-Converter-Adapter/dp/B00LUIKY4S/

 

[reedcat]

After I was complete with my Honey Badger class B amplifier I was very surprised how heavy this thing turned out to be: 38lb total, transformer alone is 18lb.
Designing a SMPS for this amp is my next project. These guys claim SMPS are more than suitable for HiFi audio projects.

 

[firestorm]

Hi,
any one got any more to add to using SMPS for powering amps?
I'm thinking of using a SMPS +- 36V for my KSA50 rebuild.

 

[Georg Kovalcik]

This might be interesting for class A amplifiers: SMPS300RAh | Connex Electronic
I have not tried them yet, has anyone ?

 

[sismik11]

Hi
Just my 2 cents.
After learning that Mr Pass uses SMPS in the Amp Camp Amp, I thought I would give it a try.

I've had really good results using SMPS in the following Class A amps:
First Watt F4
Aleph 5
Aleph mini (2x laptop brick PSU's)

To me the advantages are:
They are very quit, especially mechanically. No big humming trafo here.
They are/can be cheaper. For bigger Class A amps like the Aleph 5 I'm not sure it was cheaper, as I needed +-34V and a lot of amps.
Easy to implement
No Ground loop issues.

I would like if someone out there could enlighten me on the big disadvantages and why it has not necessarily caught on the DIY audio world yet (at least not for Class A amps). It is like the SMPS has not gotten the audiophile "Quality Acceptance" stamp! Or is it just me?

I know that the SMPS' "switches" and thus are noisy at the switching frequency, but this is usually at frequencies that are way beyond the audible frequency range. The switching can lead to some EMC issues I know, but nothing I have encountered as a problem yet.

 

[NickKUK]

I use SMPS on my class A's. A disadvantage of SMPS for audio is that when the load is low, many stock designs go into a very noisy discontinuous mode with irregularities even in the audio band. But with Class A there is never a low load (one of the few advantages of class A's poor efficiency) so the SMPS operates at a rather continuous load current so any noise is at very high frequencies and at audio frequencies the supply is tightly regulated.

Typically the SMPS data sheet states the minimum value, for meanwell that’s typically below 10% load. Class A is quite good on that, especially OTL, but AB can end up rattling between the two modes.

If you can add the heater supply to the PSU too, it helps add to keep above 10%.

I’m currently modelling a 648W SMPS 240v->24V then using 24->200 etc

 

[nigelwright7557]

I have a JLH1996 amp that runs off a cheap £10 RS +/- 15VDC SMPS at 5 watts.
As usual with SMPS dont put big caps on their output.

 

[NickKUK]

I have a JLH1996 amp that runs off a cheap £10 RS +/- 15VDC SMPS at 5 watts.
As usual with SMPS dont put big caps on their output.

Question - could you put a second switched PSU after a standard SMPS PSU? Surely that is a resistive (mosfet)/inductive(transformer) load?

 

[amplidude]

To what purpose nick? I use smps as well , mine can tolerate extra capacitors, and I added common mode inductors, they are dead silent, below 1mv ripple, current loaded, on scope it looks more like some random high frequency noise, shot noise?.

 

[amplidude]

For steady current loading, smps I believe is best, 100hz, is way to slow, capacitors jump up and down,