The info on the X.5 series internal changes are still scant. The best info I have found so far seems to suggest changes in the power supply have been included. Here is an extract from an ad for the x250.5 on audiogon: ". . . addition of single-ended Class A bias, high speed fast recovery rectifiers in the power supply, and some changes to the front end circuitry have been made." I have not however seen a complete discussion of these changes anywhere yet. |
I have found the following snippet in a current Audiogon listing for the X350.5: "The new X350.5 features improved output transistors and a redesigned single ended Class A bias circuit . . . ." |
Thank you Jazzmeup. I have also seen you are putting your X250.5 on sale. What are you going to replace it with? What aspects of X250.5 are you finding dissatisfying, if any? |
Thanks Irish65. I am planning to call Peter at Pass next week, as -- per my info -- by now they should have a working X600.5 prototype. It would be also interesting to hear from audiogoners who have already heard x350.5 in person, or who are planning to acquire one. |
Some more tidbits I just gathered from Pass: while specs on new X.5 series will be virtually identical to older X series, the implementation of the class-A portion of the amps has been changed from push-pull class-A, to a single-ended class-A design. This has apparently significantly reduced time-smearing of low level detail and is generating a much more layered and finely detailed image.
The ultimate goal seems to be to maintain the high current/power of the powerplants of the X series while re-capturing some/most of sound characteristics/magic of the original Aleph series through the single-ended class-A implementation.
X350.5 is complete and is being delivered to dealers. X600.5 still in engineering. Stay tuned. |
Today I spoke to Kent, rather than Peter. Peter was home with the flue. Kent said he spent some quality time a few weeks ago with X350.5.
He indicated that X350.5 has the very best sound he has heard this far, and not by a small margin.
According to his particular taste, the previous series lineup, in descending order of preference for him went: X600, X250, X350, X150.
He seemed to indicate that in the X.5 series things are very different. As nelson Pass proceeded in re-designing from X150 upwards, he put more and more of his own sound philosophy into the new models. So while X150.5 was definitely a positive step in the right direction, X250.5 was significantly better than X250, and the difference between old X350 and X350.5 is apparently even more remarkable.
Kent's new descending order of preference is X350.5, X250.5, X150.5.
The X600.5 will not experience 'first sound' until after mid December, and I intend to call back Pass Labs at that time. Will the delta between X600.5 andd X600 exceed the delta between the immediately lower model? Kent of course would not commit. Stay tuned. I suspect the entire new lineup may be ready for CES 2005--my inference only, not a tidbit from Pass. |
I'll be out of touch for 36 hours. Keep the discussion going in the meantime. Some dealers are already stocking X350.5. Someone should give these guys a buzz. |
Sigmund, it will be interesting to hear your impressions of your new X350.5 as you keep breaking it progressively in. |
Longho68, the X600.5 will not be available until the first part of the new year. You won't be able to audition them until then. I do not know the efficiency of your Sony speakers, you I can't really comment on what kind of amp you may need. |
hocklin, have you considered calling Pass Labs directly? Folks at Pass are extremely helpful. Try:
Pass Laboratories,
PO 219,
Foresthill, CA
95631 -
Voice: 530. 367. 3690 -
Fax: 530. 367. 2193 -
www. passlabs. com
have a chat with Kent and let us know what you hear. |
The Pass Labs web site has just been updated with information on the new X.5 series. See the following url:
http://www.passlabs.com/products.htm
In particular, the page on the new x600.5 has information on some of the electric design improvements, as well as some photographs:
"**Expected to ship in the first quarter of '05**
The X600.5 is the natural progression of the X600. Changes include improvements to power transformers, paralleled high speed / soft recovery rectifiers, improved AC EMI filters, more paralleled power supply capacitors, increased supply RC filtering, refinements to the front-end input circuits, and the addition of single-ended Class A bias circuits for balanced single-ended Class A at low power levels.
All of these changes bring the X.5 series closer to the sonic signature of the XA series amplifiers.
The X.5 series feature the distinctive front panel meters indicating of the level of current running through the output stages that have long been the visual signature of X amplifiers.
The X600.5 accepts both single-ended and balanced inputs. . ."
The X600.5 should become available early in the new year. It's smaller brothers are already shipping. While we wait for X600.5 to be completed and to start shipping, I love to hear from any new X350.5 owners with their live impressions/findings. |
Irish65, which model are you breaking in exactly? Thanks, Guido |
Thank you Irish65 for the clarification. |
Just spoke to Peter perkins at pass today and got an update on the upcoming X600.5. The engineering prototype device has now been making music for a while.
According to Peter, the team at Pass is now auditioning what may very well be the final tweak of the design. Everyone seems to be happy about the results, but the final go-ahead to close the engineering/design phase and transition to full scale production, will come only after a final audition/approval by the company CEO.
Peter suspects that full production may be under way by the end of May 2005.
I asked specifically about audible differences with X350.5. Peter answered that while there is a lot of similarity with X350.5, the X600.5 has even greater ease, liquidity, bass control, channel separation, and overall 'sparkle'. He suggests that the difference is not due to any design change, but to the complete separate chassis implementation and the dedicated power supplies in each monoblock. |
TJ, not only I was impressed by the findings in your review of the X350.5, but I was equally amazed by the consistency of all the positive comments of the other users following your excellent review. Nelson must truly have created something special! |
hocklin, I suspect you may find the old X600 to have greater authority and to be slightly leaner, while the newer X350.5 to have greater refinement, delicacy and control. |
Apologies to all. . . I corrected my previous post. I meant to say that the x600 was likely to be found a little leaner, not the 'x600.5'. Clearly a 'ooops!' |
Magichandslarry, did you perceive any other difference between X350.5 and X600.5 except for power? Please elaborate. What is the rest of your system? What music do you listen to?
|
Pass Labs is introducing a new series of amps, dubbed the XA.5 series. Some initial details on three of these amps have been posted on the Pass labs site in the last few days: XA330.5, XA60.5 and XA100.5. They seem to differ from the original XA series in that power doubles into 4 Ohms and input impedance has been raised to 30KOhms. See:
http://passlabs.com/products.htm
If anyone has any further info or listening experiences, please do post them here. |
