No, I own the piece. To tell the truth, I don't know what tubes are in it. I'll have to open it up and check. |
Thank you, gentlemen.
I am playing with a First Sound Presence Deluxe tubed line stage, which has an output impedence of 1700 ohms. It's very happy with my CJ 11a at 100K ohms input impedence. But with the Pass X-150 (spec sheet says 22K balanced, not sure what it is unbalanced, which is the way I am running it), the sound is, if anything, a bit bright and over-etched. No problems with bass or dynamics, definitely not lifeless, just tilted up a little. From your descriptions, it doesn't sound like this is a technical mismatch, however. Could be a listener mismatch :)
dan |
And now, the First Sound sounds too dull and soft with the Pass. These days I am using a 4M run of interconnect, which could be a factor. Or I could be losing my mind.
Dan |
Thank you, Bob. Great info! I think that making this kind of modification is beyond my comfort level, however. Would there be any way to fashion an interconnect "extension" that would add the resistance and let me see, on a diagnostic level, whether there is a significant change in the sound if I increase the impedence? |
No bass problems, actually, so that suggetsts no impedence mismatch. I need to experiment with cables and will also try power cords.
Wouldn't it be great to have a concise set of rules of thumb for system problems? Guidelines for identifying an impedence mistmatch, or cables with capacitance that is too high, too low, etc. Am I dreaming? It's just that it feels like most of the time I'm drifting around rudderless when some basic principles would help the navigation a bit.
While I'm at it, let me offer up my idea for the audiophile test CD I'd like to see. The Chesky Ultimate Demo disk is pretty good, but I'd like to see someone produce a disk that demonstrates the unwanted side of things. This is what grain sounds like. This is what midrange suckout sounds like. This is bad VTA ... azimuth mis-alignment. This is wooly bass. Clipping, even vs. odd-order harmonic distortion. You get the idea.... Even though the playback system would alter what you are hearing, I think you'd be able to get the picture if it is presented relative to a reference. Would be tremedously helpful to me in terms of calibrating my vocabulary with others.
-----Dan |
I wouldn't know how to create such a disk, but I would put up some money to get it produced. Anyone interested?
As I thought about this, it occured to me that we might be able to capture noteworthy sonic signatures as well. Going out on a limb here, cause I know this is problematic and full of pitfalls ... if there were a way to convey the "classic" sound of CJ, of SET amps, selected eras from Krell, ARC, etc., the Koetsu sound vs. ??? Not a substitute for evaluating products, but it could have value in helping people who haven't heard it all (like me) to organize their preferences. |
Thanks for all the input everybody. It's the damndest thing, but the brightness has gone away. I loaned the First Sound to a friend for a few days, and ever since its return it has not sounded bright at all with the Pass amp.
This hobby can be so maddening sometimes!
--dan |
Nine months later, I still wrestle with these same issues. The First Sound sometimes sounds too dull (or soft) and sometimes it's plenty alive. Honestly, I think it is variability in my hearing that does this. How can it be that one week I'm ready to sell all my tube gear and the next I want to dump the solid state? That's why I still have both.
dan |
Thank you for the pointer to your earlier post, unsound.
I have a simple multimeter. Is it possible to measure the input and output impedences of my components with the meter? (I ask this because there is no publshed spec for my Pass amp in single-ended mode.) |
So if the Pass amp is 22K balanced, it is 11K single ended? And with 1700 ohms output impedence on the First Sound preamp, my situation is sub-optimal, right? |
Thanks guys.
I use HT Pro Silway II 2M interconnects between the two. |
So...I asked Nelson Pass (duh!). He says that, yes, it is 11K single ended. He added that I could insert
resistance in series with the input if I like. The gain of the X150 is about 30 dB, so if I put 22K in series I would still get 20 dB gain.
What do people think of this idea?
By the way, the reduction in gain should not be a problem, at least on the face of it. The lowest setting of the First Sound is sometimes too loud as it is. |
I think the second suggestion is a winner. I'm pretty sure I can handle the soldering, but--and I'm embarrassed to ask this--the resistance should be added to the "hot", right, and that is which, the inner plug or outer jacket on an interconnect? And, are resistors directional?
While I'm at it, I am also embarrassed to discover that I have been misspelling impedance all this time. |
