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A frightening thought:
Can Pass whip up a 6 or 8 channel version of this?
Pass Laboratories XP-32 line preamplifier Jim Austin June 2022
Jim Austin wrote about the Pass Labs XP-32 in June 2022 (Vol.45 No.6):
I recently replaced my two-box Pass Laboratories XP-22 with the three-box XP-32 from the same company. I had been quite happy with the XP-22, but when JA1 reviewed the XP-32 very favorably, I decided that the review sample should not leave New York City without a listen in my own system. Pass Laboratories was happy to let me hang onto it for a while.
As I already wrote, I've been happy with the XP-22. If you'd asked me to describe its deficiencies, I wouldn't have been able to answer. It's a transparent, very literal preamp that lets all the music through (or anyway, I thought it was letting through all the music—more on this momentarily) while adding that special something that a good preamp adds. It gets out of the way, yet it somehow makes the music sound better, with a touch more body and life than with no preamp at all. (Anyway, because I play both vinyl and digital, going preamp-less is not a practical option for me.)
I won't waste space on extensive technical descriptions; for more information on the XP-22 and XP-32, see the original reviews. A key difference between the two is the number of chassis. The XP-22 has its power supply in one chassis and everything else in another. The XP-32 has the power supply and control circuitry in one box then separates the L and R channel audio circuitry into the two other boxes.
Three boxes take up a lot of space, especially if you don't stack them, and the spacing of my Butcher Block Acoustics rack is just a tiny bit too narrow to allow even two of these chassis to be stacked. The XP-32, then, takes up three full spaces on my rack. Fortunately, I have a very large rack, with four levels, each level with space for three components side by side.
I inserted the XP-32, allowed it to warm up, and put some music on. It took me no more than five minutes to decide to keep the XP-32. Why? The XP-32 was just slightly more explicit than the XP-22. It was immediately noticeable on any music I played. The metaphor of the veil being lifted, or ripped away, is applicable here. Not that it was always obviously for the good:
At one point during those first few minutes of listening, on music I know very well, I heard a touch of brightness I hadn't heard with the XP-22. Brightness isn't good, but I knew I was hearing what was on the recording. Sometimes you can just tell. I thought the XP-22 preamplifier let through all the music, or all that mattered, but I guess it didn't, because the XP-32 lets through just a little bit more.—Jim Austin
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COMMENTS
Re: A frightening thought
Submitted by John Atkinson on February 17, 2021 - 12:27pm
Can Pass whip up a 6 or 8 channel version of this?
I believe you can add additional audio-channel chassis, each controlled by the same control unit.
John Atkinson
Technical Editor, Stereophile
Re: Re: A frightening thought
Submitted by Kal Rubinson on February 17, 2021 - 12:41pm
John Atkinson wrote: I believe you can add additional audio-channel chassis, each controlled by the same control unit.
I was really thinking of the price tag and the rack space.
I seem to recall...
Submitted by Anton on February 17, 2021 - 1:04pm
Didn't a prominent Stereophile editor once say that it was the preamp that was the most important part of a system?
;-D
It's out of my budget, but I love Nelson Pass.
Nelson Pass doesn't do the preamps
Submitted by windansea on June 20, 2022 - 9:32pm
I think Wayne Colburn does those.
Hm, I see Sonus Faber Lumina
Submitted by liquidsun on February 17, 2021 - 2:16pm
Hm, I see Sonus Faber Lumina III used as speakers during the review. Does that mean we can expect the Lumina's to be reviewed sometime in near future? :)
Re: Sonus Faber Lumina
Submitted by John Atkinson on February 18, 2021 - 4:14am
Hm, I see Sonus Faber Lumina III used as speakers during the review. Does that mean we can expect the Lumina's to be reviewed sometime in near future? :)
My review of the Lumina III will be published in the April issue of Stereophile.
John Atkinson
Technical Editor, Stereophile
It's a pity that stereophile
Submitted by liquidsun on February 18, 2021 - 4:41am
It's a pity that stereophile didn't review the SF sonetto line so we could make a direct comparison between both lines. However it's still good news to hear :)
Re: MBL?
Submitted by John Atkinson on February 18, 2021 - 4:20am
Didn't you say that you returned it? Did you have to purchase it or is it on long term loan?
After I measured the MBL N11 for Jason's review, I arranged to hold on to the preamplifier first to use in my followup review of the MBL N31 CD player/DAC in the December 2020 issue, then to use as a reference for this Pass Labs review. It has since been shipped to another Stereophile reviewer to use as a reference for a review of another product.
John Atkinson
Technical Editor, Stereophile
Use of preamplifiers
Submitted by MarkusL on February 18, 2021 - 7:56am
I once connected my Wadia 781 directly to my power amplifiers (Pass X 600). The sound is much better with my preamplifier (Audio Research Ref 5) in between!
I know what you mean:
Submitted by Kal Rubinson on February 18, 2021 - 4:29pm
I know what you mean:
I once connected my Wadia 781 directly to my power amplifiers (Pass X 600). The sound is much better with my preamplifier (Audio Research Ref 5) in between!
I gave up on finding a suitable preamp since I need 8 channels. I run my DACs directly to my power amps and it is, indeed, much better.
Is it in specs?
Submitted by LTig on February 18, 2021 - 11:50am
I have some trouble looking at the signal to noise specs. The claim is 150 dB at max output voltage, and 500 nV residual noise, which is more or less what you expect with an output voltage of 23V and 150 dB S/N.
However JA measured 85 dB at 1 V. At 23 V we should then expect 27 dB more which is 112 dB, a whopping 38 dB less (a factor of 80). This would result in a residual noise of 56 mV, more than a factor of 100 higher, Even with bandwidth restriction and A-weighting the measured S/N reaches "only" 124 dB, 26 dB less than claimed.
Noise
Submitted by WayneC on February 19, 2021 - 2:40pm
The SN ratio was calculated from max output of 32 Volts with 1uV as the noise. The noise floor is actually lower than 1uV. It all depends how you measure it and the reference. Of course we spec it to look good, the suns output would make a good max reference. Measured on the AP with a 30 KhZ filter it is about 14 uV broadband. John's AP FFT show -120 to -140 dB range. 56 mV would be rather crappy, its a very quiet preamp.
FFT gain
Submitted by LTig on February 19, 2021 - 3:47pm
Aah, there is a typo on the specification page: 23 V max (correct is 32 V). So my calculations are 3 dB off.
14 uV noise broadband (30 kHz) is almost 30 times more than the specified 0.5 uV. May I ask under which conditions you did measure those 0.5 uV?
Regarding JA's FFT plot: one have to keep in mind that the FFT noise floor does not show the S/N value. You have to subtract the FFT gain (3dB per doubling of bin size) to get the real value. I don't know the FFT size of JA's FFT plot. With 16k FFT size the FFT gain is 39 dB. Subtracting 39 dB from 120 - 140 dB we get 81 - 101 dB which correlates quite well with JA's measured S/N.
Linn LP12
Submitted by krahbeknudsen on February 19, 2021 - 10:22am
I hope you don't mind if I point out that your turntable setup is perhaps getting a bit long in the tooth? I love the Linn and all that but at lot has happened since 1991 even in Linn world. That old MDF tone arm board is not exactly known for it's high resolving power. Could it be that your digital setup is outresolving your turntable in the time domain and perhaps that would not be the case with a modern turntable or even an up to date Linn?
Re: Linn LP12
Submitted by John Atkinson on February 20, 2021 - 7:25am
I hope you don't mind if I point out that your turntable setup is perhaps getting a bit long in the tooth? I love the Linn and all that but at lot has happened since 1991 even in Linn world...
Indeed it has, but I am so familiar, so comfortable, with the sound of my LP12-based LP system that I fear change.
John Atkinson
Technical Editor, Stereophile
Output Caps ..!!!
Submitted by a.wayne on February 18, 2021 - 6:25pm
Why on earth would you not want to run the pre Amp Direct , favoring the sound of caps maybe ..??
Btw JA ,
Are those stereophile CD’s mentioned still available ..??
Regards
Re: Stereophile CDs
Submitted by John Atkinson on February 19, 2021 - 4:15am
Are those stereophile CD’s mentioned still available ..??
Yes, see http://shop.stereophile.com/music-cds/
John Atkinson
Technical Editor, Stereophile
Thank you for the link to test CDs
Submitted by Charles E Flynn on February 19, 2021 - 11:33am
Looking at my test CDs, I found, with no jewel box, cover art, or record of purchase, Stereophile CD STPH-002-2. It was apparently the first test CD Stereophile made, released in 1990.
Why not exterior jumpers (for output caps)?
Submitted by jahnghalt on February 19, 2021 - 12:36pm
I suggest a follow up to address those coupling caps.
"The output is still capacitor-coupled even with the servo but can be bypassed with internal jumpers."
On the back panel - "no user serviceable parts"
Question for Wayne - why not have jumpers accessible to the exterior? Note all those XLR jack jumpers/
(good photos BTW)
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