Innovative Circuits
Line Regulation You May Not Believe
We built a new, better ripple rejection fixture and Superpower performed well beyond our expectations. To see how Superpower stacks up against other commercially available regulators, an SPJ78 and 3 other regulators were tested. Here is what we measured:
You may not believe these results—Superpower PSRR is below the
noise floor of our measurement systems out to 50KHz. It measures a
respectable -78dBV way out at 600KHz! Below are spectra at 19KHz. A
19KHz LM7812 spectrum is included below as a baseline reference to show
that indeed the test fixture does work.
Our customers' comments that their systems sound so much better with Superpower are backed up by measurements—order one to hear for yourself, it really is this good.
To see our original PSRR page with real world measurements of power
supply ripple removal, go here.
If you would like to see spectra of the other devices, contact
us via email at 
The new fixture uses a DC+AC driver based on the LM3886 as seen in the schematic below (click for full view). The LM3886 has wide bandwidth, sufficient output power and slew rate to deliver a good sine wave on top of a DC voltage.
We did direct comparison measurements by setting up the fixture, calibrating Vin and frequency and plugging in each of the regulators in turn. Test conditions:
Vin=16VDC+1VppAC
Vout=12V (9V for Dx7809)
Load = 240Ω
Output current = 50mA (37.5mA for Dx7809)
Iout is low to be fair to the regulators that cannot deliver high currents. Vin AC was calibrated after each frequency change.
Ripple rejection, Superpower SPJ78 12V, Vin=16Vdc+1Vac@19KHz
Two measurement systems were used, a 24 bit differential input A/D with
20KHz bandwidth and a 16 bit 195K sample/second A/D. Both were
calibrated to a 4¾ digit true RMS DMM and correlated to each other on
10KHz and 19KHz measurements where the ranges overlap and measurements
were done. Measurements were made from 100Hz to 600KHz, changing from
the 24 bit A/D to the 16 bit between 19KHz and 50KHz.
Ripple rejection, Superpower SPJ78
12V, Vin=16Vdc+2Vac@19KHz
Ripple becomes visible by increasing the AC input to 2Vpp, seen above at about -110dBV.
Ripple rejection, Superpower SPJ78 12V, Vin=16Vdc+1Vac@600KHz
The 600KHz point was made with the magic of aliasing (a.k.a. undersampling), where the "carrier" folded back into the baseband at about 15KHz.
Ripple rejection, Fairchild LM7812, Vin=16Vdc+1Vac@600KHz
Spectrum of a Fairchild LM7812 tested at 19KHz for comparison.