Rowland PC1 PFC on Capri pre early findings


I have just re-inserted a Rowland PC1 Power Factor Correction (PFC) device in my system 1 hour ago. It is feeding a Rowland Capri preamplifier. Previously Capri was powered directly by a Purist Anniversary PC plugged into an AC wall outlet. Now the Purist is powering the PC1, while the Capri is being fed 384V Direct Current (DC) by the PC1 through a small Rowland supplied pigtail looking somewhat non-denominational. The PC1 is designed to increase the operating efficiency of the device that it is applied to and to eliminate capacitor charge ripples caused by AC. It was deliberately designed for high current Rowland, and not for the Capri pre, although the Capri is compatible with it without any changes of jumpers etc. . .; this means that what I am doing here is purely an experiment limited in scope to the Capri.

I have been playing only 1 CD on repeat this far: Nora Jones 1st CD, so my findings are just very early surfacy impressions. PC1 seems to have extended the frequency range top to bottom; bass appears to be further defined with greater authority/punchiness/control; imaging appears to have acquired enhanced focus. . . this means that Jones's head actually seems more contained, centered, and perhaps slightly smaller than before; instruments are more localized in the 3 dymensions; stage is wider/deeper; there are more harmonic 'bristles' or texture and a more evident leading edge in small transients from percussion instruments. I am perhaps perceiving a very slight increase in sybilants and a slightly more forward presentation. . . but the PC1 is not at all broken in. I will document further observations as the PC1 breaks in and I play other CDs.

One more potential variable is the Rowland-supply power pigtail to the effect of the PC1 on the Capri. Would an upgraded DC pigtail have any audible effect?

For your info, The PC1 can be applied readily to the Rowland Continuum 250 and Capri without any setup changes because these devices have autosense multivoltage power supplies. the 102, 201 and 501 amps require some alteration in fuse setup. The Concerto products require both a fuse setup change and a change to internal jumpers. PC1 is not applicable to JRDG 300 series amps nor to the JRDG Continuum 500 integrated, because these devices already incorporate PFC circuitry. Note that the PC1 is NOT a general purpose power conditioner and is not compatible to any arbitrary device/brand. I have no information about applicability of PC1 to older Rowland amps. It is likely not compatible with amps and pres from other manufacturers . . . so do not try wild experiments with the PC1 without consulting and approval from your dealer, JRDG and the manufacturer of your amp/pre. The PC1 retails for $1500. It is available from Rowland dealers like Soundings HiFi of Denver (Co) (303) 759-5505.

The rest of my currently active configuration consists of: Teac Esoteric X-01 Limited, Rowland 312, Vienna Mahler v1.5 speakers. Capri+PC1 is currently in use instead of my ARC Ref 3.
guidocorona
Hi MrB, I am not sure about power supply in Continuum 500. I'll find out and will let you know ASAP. . . . probably in a dedicated thread. . . no worry though, I'll create a link from this one.
Guido,

So the device PC1 is outputing 384 volts dc into the Capri? Is this peak voltage or static. Is the Capri self regulating at its input? What is the prime operating voltage of the Capri? Digital power supply I suppose?
Tom
Hi Tom, I believe the PC1 outputs a static voltage. Capri has an autosense switching power supply. It requires no voltage/frequency adjustment for WW operation. I do not know the internal operating voltage of the Capri. Guido
04-13-08: Mr_bill
Mr Guido,
Great findings and keep sharing!
Does anyone know if the new Continuum 500 will have analog power supplies for the amps like the 300 series or the switching supplies like the 501's?
Thanks,
Bill

As far as I know new 312 and new version of 301 monos use switching power supplies. They both use PC1 PFC internally.
Branimir, you are correct, spoke to JRDG today. 300 series rowland amps implement some form of regulated switching power supply fed by a power factor correction circuit (PFC). In answer to Bill, Continuum 500 also has switched and regulated power supply, but -- if I understood correctly -- its PFC circuit has much greater capacitance than that built into 300 series amps or in external PC1 unit. . . .