Possibly Dumb Question re:Battery as a power supply

@lewm , just so. An MC7812 requires 19VDC if I remember correctly. And it's hard to know the characteristics of any internal regulation or the motor, and it may not even be obvious about how motor speed relates to platter speed.

Doable, sure. How much of a project? Depends on your luck and how much test equipment you have lying around. If you don't have any test equipment, it'll take some pretty dumb luck not to void the warrantee.

Only way around it I can see is to measure (or otherwise determine) the voltage on the manufacturer's battery pack. Then replicate with a comparable rechargeable pack of your own. And don't forget to protect the pack with a diode and protect the motor with a fuse!

Drop out due to VR is usually dependent upon many factors including current draw most importantly. I built a PS for my Klyne 6LX which has regulators on board the audio chassis. The PS needed to put out not more than 4-6V above the needed regulated V. I am sure an 18V battery or a 24V one at most would work for the clearaudio. We don’t have enough info even to guess.

I should have mentioned another issue: variability in parts. For example, the MC7812 is specced to regulate +/- 4% or so; which means that if you buy 5 of them, one should be within 1%. That’s 33 RPM to 33.6 RPM. Assuming you need it. Maybe you don't.

Like I said, it’s a project. You might have the time and inclination for it, or you just might want to listen to music.

The OEM wall wart is a 12V 600mA regulated switching power supply, so long as a battery can supply a regulated 12V with min. 600mA it should be find. Since the Performance DC feathered fine speed adjustment on the back of the turntable to compensate variability in voltage difference, I think using a 7812 regulator shouldn't cause any problem.

https://hifiheaven.net/shop/image/cache/catalog/Clearaudio/12V1-750x750.JPG

millercarbon: Never misunderestimate the ability of the forum to overthink even the simplest things. Full disclosure: I converted AC to DC battery, did none of that, and it was audibly quite a bit better. Just not that hard. Unless you make it so.

Truer words were never written. If the Clearaudio table uses a DC motor, it is not driven directly from the wall wart power supply. At 33 RPM, it is most likely driven by 3-4VDC and from an internal controller which not only regulates the voltage but has active current feedback (negative output impedance) to compensate for the motor’s negative-slope torque/speed curve, without which, the motor will slow under load.

Regulating an AC-to-DC supply is done to remove any AC ripple from the output. The turntable should work just fine from an unregulated battery supply as there will be no AC ripple present. Regulating a battery supply in this case would do nothing other than complicate the application and waste heat and power. The rest of this discussion is just noise.

FYI, MC7812 regulators have a dropout voltage between 2.1 and 2.4V, depending on the device, so you would need 14.4VDC or greater for proper regulation. LDO regulators (Low Drop Out) exist with dropout voltages as low as 200-300mV, but they can become unstable and oscillate without careful layout and compensation.

Advice to the OP: As millercarbon alluded to, don’t over think it.