Jeff Rowland Pre with Pass Labs X350.5 or X600.5


I am keen to know how well does Jeff Rowland Preamps like the Synergy IIi or the Coherence work with Pass X350.5 or X600.5 amps?

Any inputs will be most appreciated.

Cheers!!
arupg
Responses
05-24-08: Dcstep
I think that the current Capri are Criterion are the pre-amps to consider for you Pass amps.

The interface with your Pass should not be any issue.
Dave
Dcstep (System | Reviews | Threads | Answers)

On what criteria do you base this recommendation? Would you elaborate, please?
Hi all, my apologies. . . I am not at all familiar with older pres from JRDG. . . but -- for what it matters -- I have reasonably good experience with the current JRDG Capri, which has been in my system for the last couple of months. I still contend that it is a magnificent device, although after several hundred hrs of breakin of Capri connected to the PC1 PFC unit, I am coming to the conclusion that I prefer it even better without PC1. . . greater extension, authority, staging, imaging, micro detail, macro/micro dynamics. My early Capri+PC1 findings were based on both devices rrelatively fresh from the factory, and my findings after break in appear to differ with my original ones. It is fair to remind that PC1 was designed for high current devices such as 102, 201, and 501 amps, not for low power devices like Capri. JRDG does not necessarily support use of PC1 on Capri. As for Capri matching Pass amps. . . Pass amps have an input impedance of 22K Ohms, while Capri has an output impedance of about 40Ohms in balanced mode. . . compatibility should be without problems. Pass and JRDG being balanced designs, I suggest connection of JRDG pres to Pass amps using XLR ICs.

I confirm that I originally preferred Capri over Ref 3. I will resume comparisons of Capri with my ARC Ref 3 in a couple of weeks, after I receive a set of 6H30DR NOS tubes.

And yes, Capri being this good, I am already fantasizing about the upcoming JRDG Criterion 2-box pre, which is expected to start shipping early in Q3.

Guido
My Pass XA-60.5 amps have an input impedance of 30K Ohms balanced, and 20K ohms unbalanced.

The Synergy IIi has an output impedance of 80 ohms. Not sure about the Coherence II.
Coherence II appears to have an output impedance of 50Ohms. See:
http://jeffrowland.com/ClassicSpecs.htm#Coherence
On the same page above, you will find Synergy II appears to have an output impedance 40Ohms unbalanced and 80Ohm balanced.
If input impedance of Pass amps ranges from 20KOhms to 30Kohms, compatibility with Coherence II and Synergy II is all but assured. G.
Thanks for all your posts.

Can someone tell me whether the Synergy 2i or the Coherence 2 with separate Rec outputs can be used as a tape loop for using a signal processor.