24 volt smps conversion to split output +24 / -24 volts

Hi I am building a class-a six channel amp and want to convert a 1000va single output 24volt power supply to split output IE +24v / -24v.
I have searched around and there are a few tutorials for low power applications, but found one on utube which may be suitable for high power. I will be using heftier diodes.
What do you think



YouTube
 
At that kind of power they usually are though...

Plan B would be using a hefty inverting DC/DC buck converter to generate -24 V (20+ A worth) from +24 V. It needs to be able to take 48 V of input voltage.

An inverting DC/DC is basically the same as a buck converter with two nodes swapped: V_out becomes GND, and GND becomes -V_out.
 
Hi I am building a class-a six channel amp and want to convert a 1000va single output 24volt power supply to split output IE +24v / -24v.
I have searched around and there are a few tutorials for low power applications, but found one on utube which may be suitable for high power. I will be using heftier diodes.
What do you think



YouTube
I think it won't work when a real load is put on the output connected through capacitors, caps do not conduct current when DC is applied.

Mike
 
Thanks for the replies, much appreciated.

What would you use which direction would you go in to convert single 24v smps to dual 24-0-24v Lambda SWS1000L-24.

1000watt smps output for use with a class-a amp.

At a guess power requirements for amp will be 500 watts as an average figure, may rise during transients.
 
I would either sell the Lambda and buy a PSU that is designed for the purpose or change the amp selection to a single supply version to suit the PSU that you already have.

Why take a $650USD PSU and make it mediocre with buck converters and 'YouTube tricks' (which may well end in tears) when a properly specified PSU and amp combination would be better, safer and more reliable?
 

PRR

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...At a guess power requirements for amp will be 500 watts as an average figure, may rise during transients.

No, a Class A amplifier pulls *constant* power for any signal.

Which suggests you have not really thought about this.

Maybe I am wasting my breath/fingers, but.......

Many "1000W" power blocks will not last long at 1000W, let's derate to 600 Watts power.

Since this is a 6-channel plan, the math is easy. DC power to each amplifier is 100 Watts.

Class A maximum efficiency is ideally 50%, but more like 40% with real parts at low THD, and can be much-much worse (<25% for constant-current load, to 8% for resistor coupled). So we aim for 24+W per channel.

To get supply voltage we need Load Impedance. You have not said what the loads are. (In Class A it is critical.) Assume 8r. For 24W we need 14Vrms or 17V peak.

Something comes to mind. A well-proven and simple Class A amp in this power range is the MoFo. Go read that. All 50 pages. Scaling from 19V to 24V supply will make more power out, need larger heatsinks, etc. But it is simple chimp-work to do one bigger and repeat.
 
Hi. The actual amp i am building is a 25 watt pass labs, got the circuit board from this website. There is no way to use that from a single output psu, is there?

No. (you don't mention which Pass amp it is, but I doubt it makes a huge difference)

To summarise this thread once again: If you already have the amp, buy a suitable PSU to match. If you already have the PSU, find an amp that matches what the PSU delivers. What you are trying here is at best inefficient and compromising the quality of your build - and at worst, unsafe and dangerous to yourself and those around you.
 
Thanks!

I do hear what you are saying. Got the psu from ebay, some guy selling them for £50 each, whereas the rrp is £450. Couldn't resist the bargain. Hoped there was some way to use it but obviously there is not.
Am using smps because i keep getting a buzzing sound from linear psu.
This is the transformer i am using

https://cpc.farnell.com/multicomp/mcta225-15/transformer-225va-2x-15v/dp/FF01584
Am connecting the two 15v secondaries together to produce15-0-15v
Is there any way possible this could be causing the noise, do some transformer not like being hooked up like this for any reason.
Some people put small caps across the primary side, is this something worth looking into.
Sorry, i know this is clutching at straws, but i can't think of any other explanation for the noise.
 
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and want to convert a 1000va single output 24volt power supply to split output IE +24v / -24v.
Power supplies are rated in watts, not volt-amps. Transfomers are rated in volt-amps because they are AC and power-factor is important and apparent power and real power can differ. Anything DC is measured in watts as all power is real power.

There's no point paying for an expensive medical grade power supply and butchering it. You pay a lot for medical grade and then throw away everything that justifies the price bracket!


Its like buying a Rolls Royce to strip down and rebuild as a campervan!


And anyway Meanwell do much cheaper medical grade supplies.