24/48VDC PSU for Aurora Audio / Neve-style gear

[hildy]

Hi,

Looking for an AC-DC SMPS power supply which supplies 24 and 48VDC--need them for some Aurora Audio gear I am currently repairing. Tried reaching out directly to Aurora but looks like they are no longer in business any more.

A quick search on mouser Brought up a meanwell unit, but it is too big for the chassis. Needs to fit in a 1U rack mount and be less than ~140mm long. I am having a hard time believing how hard it is to find a PSU with these specs, but here we are.

Hairball audio has a PCB for a linear supply which does this, but I am hoping to just find a drop-in unit which doesn't need to be built.

Any ideas?

 

[Ike Zimbel]

Hi,

Looking for an AC-DC SMPS power supply which supplies 24 and 48VDC--need them for some Aurora Audio gear I am currently repairing. Tried reaching out directly to Aurora but looks like they are no longer in business any more.

A quick search on mouser Brought up a meanwell unit, but it is too big for the chassis. Needs to fit in a 1U rack mount and be less than ~140mm long. I am having a hard time believing how hard it is to find a PSU with these specs, but here we are.

Hairball audio has a PCB for a linear supply which does this, but I am hoping to just find a drop-in unit which doesn't need to be built.

Any ideas?

Last I knew, we were still in business. Let me check with Geoff and see what we can do. Where are you located? Also, what's wrong with the existing supply?

 

[Khron]

What sort of currents on each of those two rails, do you need?

 

[Bo Deadly]

Note that you really need to be careful about matching the SMPS to the load. Otherwise, it could modulate the output and create noise.

You also need to watch out for too much load (such as from too much capacitance) which will trigger output protection (aka "hiccup mode") and generally not work at all.

Fortunately 24V is a very common voltage. And to make 48V, you can simply stack another 24V on top (provided the SMPS outputs are isolated but they almost always are). An presumably the 48V load is much less which is also not a problem because you can just use a smaller SMPS for the upper supply.

There are other pitfalls to watch out for. Just swapping in whatever SMPS will almost certainly not work correctly. But if you provide more info, we might be more explicit about what you can do.

 

[Ike Zimbel]

The stock supply in the Aurora product is a dual 24v, so the 48v is derived by stacking those rails.

 

[jokeramik]

The best 24 Volts and 48 Volts regulator are coming from Funk Tonstudiotechnik. The best way for audio equipment.
Best regards

 

[leadbreath]

I've used meanwell 24v smps numerous times on Neve gear, no extra filtering, no extra loading...no problem...

 

[leadbreath]

Wont break the bank neither...

 

[leadbreath]

 

[leadbreath]

Fits in 1u...

 

[macleod69]

Hi,
You can look at proaudiogc.com.
there are two types of power supply 24V and 48V.
Regards

https://proaudiogc.com/pcb-shop/pcb...4-90mm-x-93mm-x-16mm-alim.html#/5-psu_gc73-v3

 

[thor.zmt]

Roll your own.

MC34063A is considered obsolete, but readily available and easily implemented.

Depending on load, add an external TO-220 Mosfet to handle the required current. With a suitable high voltage MOSFET you can even generate pretty much any Voltage.

This can make a ~12V - 24V Step-up including stepping up from 20V/5A from a USB-C Charger (with a suitable interface PCB). You can create a 48V Rail at less current than the 24V rail using a charge pump system stacked on top of the 24V rail.

More modern IC's can of course be used.

In fact, the very latest USB-C PD 4.0 standard allows 48V/5A (240VA) so that could allow a single USB-C charger brick to power everything. Use a railsplitter and voila, +/-24V or 24V + 48V. Just add serious LC filtering for the switching noise.

Thor

 

[Ike Zimbel]

Last I knew, we were still in business. Let me check with Geoff and see what we can do. Where are you located? Also, what's wrong with the existing supply?

PM Me. I have been in touch with Geoff and should be able to arrange a supply for you.

 

[hildy]

Last I knew, we were still in business. Let me check with Geoff and see what we can do. Where are you located? Also, what's wrong with the existing supply?

Hallelujah! lol.

Been trying to find you! I've sent emails out where I could. We're in Brooklyn NY.

The problem: We've got a customer who has checked in a bunch of gear with us with power supply issues. All sorts of rack mount stuff with various types of power supplies. It seems he has some "power conditioner" which keeps frying all his gear. (I am pretty sure it's one of those big transformer set-ups which turns the single-sided wall AC into a differential supply. Gives you that warm tone... of smoked PSUs.

LOLs aside, I haven't done a deep diagnostic on the SMPSs for the aurora gear because we're pretty heavily backlogged with repairs over here. (it's usually more time/cost effective to simply swap assemblies). One strange thing we found was it looks like the ground for one of the 24V rails is jumpered into the +VDC rail of the other 24VDC supply. Could't tell if that was the result of a previous bad repair job, or if it's supposed to be that way... and if so, why?

In any case, I'll take 2 new PSUs please!

edit: I've attached a pic of the PSU. It's a little hard to see, but the green ground wire from V1 is going into the hot side of V2. It's piggybacked under the red wire.

 

[Ike Zimbel]

Just FYI, I am the Canadian rep and service centre for Aurora Audio. I just happen to have more bandwidth than Geoff for dealing with this stuff right now. Please PM me with your contact info. BTW, the wiring you mention is how you derive the 48v.

 

[hildy]

What sort of currents on each of those two rails, do you need?

it's just 2 mic pre's on one of the units, and a channel strip (pre + eq + comp) on the other units. With the audio works and some LEDs and phantom, probably not more than a couple hundred mA. if that.

 

[hildy]

The stock supply in the Aurora product is a dual 24v, so the 48v is derived by stacking those rails.

Ah ok, so you've answered my question about the way the two 24V rails are wired up. Was unsure, since there is also a 48V rail (for phantom)

 

[hildy]

Wont break the bank neither...

I hear ya. in fact, I was really convinced I could find just the right one with a 24 and 48 rail... which I kinda did, but it was huge.

 

[hildy]

Roll your own.

MC34063A is considered obsolete, but readily available and easily implemented.

Depending on load, add an external TO-220 Mosfet to handle the required current. With a suitable high voltage MOSFET you can even generate pretty much any Voltage.

This can make a ~12V - 24V Step-up including stepping up from 20V/5A from a USB-C Charger (with a suitable interface PCB). You can create a 48V Rail at less current than the 24V rail using a charge pump system stacked on top of the 24V rail.

More modern IC's can of course be used.

In fact, the very latest USB-C PD 4.0 standard allows 48V/5A (240VA) so that could allow a single USB-C charger brick to power everything. Use a railsplitter and voila, +/-24V or 24V + 48V. Just add serious LC filtering for the switching noise.

Thor

I hear ya. Building one of those is no big ask, but we're working against the clock over here and have to charge for it. A reliable, careful (read: professional) build + test + install + burn-in = at least an hour = more money than just swapping in a new unit.

 

[Bo Deadly]

One strange thing we found was it looks like the ground for one of the 24V rails is jumpered into the +VDC rail of the other 24VDC supply. Could't tell if that was the result of a previous bad repair job, or if it's supposed to be that way... and if so, why?

That's almost certainly by design and completely normal. SMPS do not usually have a "ground". They just have negative and positive [1]. SMPS outputs are almost always isolated or more colloquially referred to as "floating". So you can use the output of one to make 0V and +24V and then connect the negative of another to +24 to make +48V such as for phantom power of mics. I think someone already chimed in that this particular item does this. This is also known as "stacking".

[1] Although they frequently have a chassis connection which might be marked with a ground symbol but that's not connected to the outputs.