Debalancer Box power supply (THAT 1206)

[ccaudle]

Once Upon A Time, Mouser (and probably others) sold Wallwarts and Linelumps which produced an AC output....IE, a transformer in a plastic box with all the Mains input enclosed

I think those are still available. That is probably a good choice, at these low current levels you could even use a supply without a center tap and just use half-wave diode configuration with a reasonable sized cap on each rail. Also gets the ripple back down into the range that the chips have good PSRR, as opposed to the 100kHz ripple from the DC-DC converter.

Maybe something like this Triad AC-AC wall wart from Digkey, puts out 12V, so after rectifying should be enough to regulate back down to +/- 12 with a low dropout linear regulator:
Triad 12V AC adapter at Digikey

There are other variants, if you prefer regulated 15V output there are 14V AC adapters that would be good followed with LDO, or slightly higher voltage output if you want to use a cheap standard regulator instead of low dropout.

 

[Bo Deadly]

I wouldn't bother with transformers anymore (minus scenarios where you want the transformer to cause supply "sag").

I think good engineers have studied this problem enough and we see that in production gear from virtually all of the serious manufacturers. The prevailing method depends a little on load.

For higher loads, an onboard ACDC SMPS is used.

For medium loads, an inline ACDC SMPS laptop style "brick" is used to make a common voltage like 12V and that is followed by onboard DCDC converters to make the appropriate voltages.

For light loads, an ACDC SMPS "wall-wart" is used although preferably slim ones that don't block adjacent sockets. Then, again, oboard DCDC converters follow.

For DIY I would deviate from this slightly. In production gear, filtering is designed to match the supply with the load specifically using the lowest cost combination of parts. Personally I would just use a capacitance multiplier so that the supply would be reusable (being generally low noise and a good soft-start load for different SMPS) and because I would not want to have to characterize noise and research parts.

 

[ccaudle]

I wouldn't bother with transformers anymore

In general I agree, which is why I started out with the DC-DC converter suggestion.
For this particular case the current requirement is only in the range of about 30mA-50mA, so a switching converter and associated filtering may be overkill.

 

[camshash]

Are there linear supply kits available? I dont really have a problem wiring mains devices, Ive built tube mic power supplys, Im more so looking for a plug n play option for a project this small, but if a linear supply will result in better sound quality Id prefer that. Btw I had no idea Switiching and linear supplies existed so thank you for that.

 

[Perm0]

Here's some examples;

https://www.eleccircuit.com/power-supply-regulator-15v-15v-1a-by-ic-7815-7915/

 

[Bo Deadly]

but if a linear supply will result in better sound quality Id prefer that.

Most likely it will not. Linear supplies almost always have some mains frequency hum which will be audible depending on the circuit. If implemented properly, SMPS will be superior in every way. But there are rules about SMPS that people either don't know about or ignore.

 

[moamps]

I’ve been working with SMPS power supplies for quite some time and I actually agree with everything Brian said in the post 18. But, the fact is that SMPS are getting better and better and in some applications linear power supplies cannot replace them. However, SMPS have one very important drawback. By using them, almost absolutely nothing can be learned about their design and if a malfunction occurs, the probability of repair is very small. Nonrepairable electronics, I hate that.

In this case I think the solution mentioned by Brian and ccaudle where wallwart ac adapter, halfwave dual rectifier and two regulators are used is the most practical and easiest to perform.
I would just use a wallwart transformer for 16V and 7X15 regs to get +/- 15V at the output.
for example,
https://www.digikey.com/en/products/detail/triad-magnetics/WAU16-500/4915301and
https://www.tindie.com/products/dhaillant/mini-dual-power-supply/

 

[scott2000]

Old Rane SM26...

 

[Brian Roth]

Are there linear supply kits available? I dont really have a problem wiring mains devices, Ive built tube mic power supplys, Im more so looking for a plug n play option for a project this small, but if a linear supply will result in better sound quality Id prefer that. Btw I had no idea Switiching and linear supplies existed so thank you for that.

Belayed reply. Two kit options (and both are overkill. but have plenty of outputs for any future projects):

http://www.fivefishaudio.com/diy/psu2448plus/
https://www.jlmaudio.com/shop/ac/dc-3-rail-power-supply-kit-v5-easy-mount.html?display_tax_prices=1
Both require a power transformer and the various mains parts.

There used to be a guy in Canada who was on this board and sold an even more basic kit, but I can't find his info.

Bri

 

[Youngwhisk]

I built one of FiveFish's PSU-2448 (this was before the plus). It was very easy to build . I also ordered the toroid transformer kit from him.