Jeff Rowland battery preamp - powercord influence?

Hi Breezer, I have no experience with older Rowland battery-powered pres, but have used Criterion for several years, until just about a year ago.

By definition, when Criterion was on battery power, the power cord had no effect on the sound. What is more interesting is that the Criterion SMPS is extremely isolated and regulated. This makes it less sensitive to power chords than other preamps. As a result, even when Criterion was taking power directly from the AC grid in Austin, I could detect little difference with various power cords.... Probably because the AC in my location is relatively good. But when I heard Criterion on AC in Dallas, power cords did make a discernable difference to the sound... Perhaps grundgier AC grid?

Worth mentioning that when I had Criterion I was not using the astonishing High Fedility CT-1 PCs that I am evaluating now.... It's the first time that I discovered a PC having an enhancing effect on the SMPS of my Rowland Aeris DAC, which uses an AC power supply very similar to Criterion.

Regards, Guido

Using Stealth V12 on my TW turntable battery power it does sound better.

Coherence II has a very nice, USA-made, generic 12-3 power cord. Like you'd get with a nice bench power tool or computer power supply; it's not flexible like you'd get with a hand-held power tool.

Even though it supposedly runs on the batteries, you can't actually unplug the Coherence II PS and run it that way.

When you take power away from the Coherence II (and Cadence phono section), >> DON'T DO IT << they develop total amnesia; everything has to be reset, even the phono stage. As if that's not insulting enough, you have to do a push-hold front button dance with the power supply, listening for a relay click or there are dire warnings one battery will continue to discharge and potentially cause problems. Same with power up, listening for a relay click, etc. It's just absolute Electrical Engineering 101 silliness nobody ever mentions in the reviews.

As is the lack of a little hole into which one might wish to stick a headphone plug.

Speaking of weirdness, the front panel of the Coherence II pops off, with two little spring-loaded buttons. Then you can take it across the room like a kind of gigantic all-powerful remote control. Oops, sorry, no. You need to connect it to the base unit with a weird cord of some sort (not supplied). You'll need to use the weirdly incapable remote control.

One can only believe the zany removable faceplate is actually part of JRDG's modular architecture. He uses the same basic box parts to make everything. If you can Switch faceplates, then you can use the same basic box front panel, too. See, the JRDG boxes are like LEGO, take 2 matching Side pieces, a Top, a Bottom, screw them all together. Then plop the electronics inside (lots of extra holes for all kinds of circuit boards). The only thing different about all my JRDG boxes, even the amps, is the faceplate and the backplate. Those have to be made specifically for each unit. Hence I think the Coherence II's removable front panel was a shot at standardizing the front panel, too.

Oh, and the Cadence is inexplicably a shorty unit, the sides and top and bottom are unique to it so far as I can tell. The reason I say inexplicably is why not make it standard depth? Since it's not standard depth, the phono leads have to reach another six inches or so to get to the Cadence, and we all know phono lead length is always a killer for where to locate equipment.

If I'm being honest, JR's implementation of the separate battery power supply was nowhere near fully developed, it needed another few months thought and development. Why all this is never mentioned in the reviews is beyond me, because it does become a PITA in everyday life.

I am incredibly FORTUNATE to have Guido's BEAUTIFUL Jeff Rowland Criterion (via Matt!  thanks, Matt!) and totally agree with him.  In battery mode, I have to pinch myself because all I feel are the Angels carrying me towards the sky.  I have a very nice Shunyata Python Power Cord and have a fairly new house with very clean power.  When not in battery mode, the preamp sounds stunning.  Battery is just a different level.  Guido, I hope you have been well.  Looking forward to Serie A in a few weeks!

Saluti!

When you select battery-only on the Coherence II, it's really not detectable ABX with the Coherence II itself, probably because the other components (CD, whatever) aren't running on battery ... but going battery-only IS a clear (pun intended) improvement with the Cadence phono section. (Shelter cart, VPI IV)... which, put more clearly, means the entire signal path into the Model 12 amps is running battery-only from the same batteries.