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Noise

How does SPX noise compare with other voltage regulators? See the noise spectra below and judge for yourself. All devices were tested with the same input supply, gain of 1000  measurement amplifier, and spectrum analyzer. All were measured as the AC component of 12VDC output, with no load. The vertical scale of all spectra was lowered by 60dB to adjust for the 1000x gain.

Baseline Test System Noise

Noise test baseline noise measurement

This is the noise level of the test setup with input grounded. Spectrum is captured from a Handyscope HS3 from Tiepie Engineering. How low can you go? The small spike is power line noise leaking through at 60Hz, -155dBVpk. The trace gets thicker at higher frequencies because of the logarithmic horizontal scaling.

SPX78

SPX78 Noise spectrum across audio bandwidth

Belleson's SPX has very low noise, about 8µVrms across the audio band.

Sparkos Labs

Sparkos Labs voltage regulator noise spectrum across audio bandwidth

Sparkos Labs SS7812 has very low noise, about 6µVrms in our test setup.

LT3045

LT3045 Noise spectrum across audio bandwidth

LT3045 measures just over 2µVrms.

Dexa/NewClassD LC7812 UWB Mk2

SPX78 500mA dynamic response

Surprisingly, the new Dexa LC7812 UWB Mk2 measures about 110µVrms in our test setup.

TPS7A4700

TPS7A4700 noise over audio spectrum

Very low noise, measures about 3.5µVrms in our fixture. Its other characteristics such as output impedance and dynamic response are not very good.