Analog Corner

CH Precision's P1 phono preamplifier, which I wrote about in the April 2017 issue, is not going back to its manufacturer. The longer I used it, the more obvious it became that I couldn't part with it, even though I said I couldn't afford it. The cost was stiff even at the accommodation price (at retail, the CH Precision P1 and its optional X1 power supply are $31,000 and $17,000, respectively, footnote 1), but I decided I could afford it, and bought it for myself as a 70th-birthday present. No, I can't hear as well as I did 30 years ago, but my listening is better than ever.

What good was the money doing in the bank instead of in my audio system, where I can enjoy listening to it? Now I happily shuttle back and forth between the CH Precision P1 and the Ypsilon VPS-100 Silver Edition phono preamp.

Maybe it's nerdy, but I love getting e-mails like this one:

Mr. Fremer—I just listened to/watched your YouTube videos of your rig playing the Stones' "Play with Fire" (mono), the Beach Boys' "In my Room," and Lou Reed's "Walk on the Wild Side." Just one question: How in the world does the music coming out of my outdated, single-speakered iPad 4 sound so open, balanced, natural, relaxed, and liquid-smooth?! I don't get it. I've never heard those recordings sound as good. Simply stunning and incredible. My brain can't comprehend this! Out of my single-speaker iPad?! I've listened to LPs since the late '60s and continue to do so . . . but I must say, I've never been as immediately impressed as I was hearing your YouTube videos. I am now convinced that better equipment plays better. And to think, what I heard doesn't begin to match the experience of being in your listening room. I'm hesitant to say this, but maybe shelling out $35,000 for a system is worth it. I'll never do it, but I can understand why those that can afford it do it. I am floored.

Convincing people that high-performance audio gear makes a big difference by having them listen to it— even when degraded by YouTube (though if you post HD files, the lossy compression is gentler)—is far more effective than haranguing them in print. Even those offended by the high prices of some of this stuff have backed down when they've gotten to hear it.

One thing I didn't cover in my April review was the effectiveness of, and therefore the need for, the P1's outboard X1 power supply, which is almost as big as the phono stage itself. (Both are 17.3" square; the P1 is 5.25" high and weighs 44 lbs, while the X1 is 4.7" high and 55 lbs.) The P1 has its own supply, and both are simultaneously AC powered. With the addition of a second regulation board ($3500), the X1 can also power a second CH Precision device, including CH's D1 SACD/CD transport/player and its C1 DAC.

Adding the X1 did a few things that I didn't notice until I turned it off again. They weren't ground-shifting differences, but they were significant. With the X1 off, the P1's image solidity and pile-driver–like rhythmic certainty, while still superior to those of most phono preamps I've heard, were somewhat diminished, and its velvet glove-like grip lost a small fraction of its considerable authority. But the P1 by itself is so quiet that I can't say that adding the X1 produced even "blacker" backgrounds.

What most impresses me about the CH Precision P1 is, still, its chameleon-like lack of an audible personality. With a bright, somewhat hard, primitive, but enjoyable recording like Buddy Holly's first album, The "Chirping" Crickets, from 1957 (mono LP, Brunswick/Analogue Productions APP 109), it sounded bright—but with a rich, warm recording that succeeds in bringing to mind Rudy Van Gelder productions (but with far superior piano sound), like Nick Culp's self-produced The Culprit's Blues (LP, Gutbucket GB-1001), there was no hint of "transistoritis" or etch, or hardness of any kind. The transparency, lushness, and transient clarity of this "semi-retro" recording showed off what the P1 delivered (footnote 2).

If you've gone all in on the P1, don't skimp—get the X1 too. I did. I'll get back to you on that after I've heard every phono preamp in the world.

Finally, if you own a cartridge with a super-low source impedance, such as the Transfiguration Proteus (1 ohm) or the Kubotek Haniwa HCTR01 MkII-6T (0.4 ohm), you need to hear these through a current-amplification phono preamp like the CH Precision P1.

darTZeel NHB-18NS Mk.2 preamplifier with built-in phono stage
DarTZeel Audio, the Swiss company dedicated to listening first and measuring later, has introduced a completely redesigned version of its battery-powered NHB-18NS preamplifier that is vaguely similar to the original in looks and in name (footnote 3). Based on its list price in Swiss francs and the exchange rate at time of writing, the NHB-18NS Mk.2 costs about $38,000.

I reviewed the original NHB-18NS ten years ago this month, in the June 2007 issue, and bought the review sample (it cost $23,250) without really thinking about its impracticality as a reviewing tool. The original lacked a volume control that could be set to a reference level; its optical-type volume knob just spins around and around, with no stops at the extremes of its range of effectiveness. I couldn't know where I was in terms of level, which meant that I was switching blind between inputs. That could be—and was—harmful to tweeters' health. Lesson learned: Think carefully through everything before buying anything.

Still, I didn't regret buying the NHB-18NS, despite its built-in moving-coil phono preamplifier's less-than-accurate RIAA equalization and the phono section's lack of adjustability (unless you were willing to open up the case and solder resistors to circuit-board pads), and the preamp's transformer-coupled balanced input and output, which had less than flat response. But I was going to use Ypsilon's VPS-100 phono preamp with the darTZeel and avoid the darTZeel's balanced connections.

What I loved about the NHB-18NS was its velvet-smooth yet well-detailed sound, as I described in my review—it bridged the gap between the sounds of solid-state and tubed preamps. Even the too-frequent battery charges, though a pain in the butt, didn't bother me too much.

The NHB-18NS Mk.2 solves all of the original's problems, and then some. It has a digital display on its front panel that shows the volume level in decibels; the balanced input and output are now active, not transformer-coupled; there's a new operating system I won't go into here, other than to say that you can now adjust the balance via the remote control; and the batteries have never run out of juice during a listening session, so the Mk.2 never once entered AC mode for the many months I've had it in my system.

The NHB-18NS Mk.2's new built-in MC phono preamp is sonically far superior to the original, and is more adjustable than many outboard models, particularly in terms of gain. You can select among gains of 57, 60, 63, 66, 69, and 72dB. The loading options are 43, 50, 75, 100, 150, and 300 ohms, or you can solder in your own choice. With a jumper, you can enable 47k ohms, but, as darTZeel's founder and designer, Hervé Delétraz, notes in an addendum to the manual, "Playing with 47k or no load using the 'bonus' setting gave more 'air' at first glance, however it was artificial." There's also a very useful subsonic filter, and a Neumann fourth-pole EQ option, both defeatable. (I switched off the Neumann fourth-pole filter for reasons previously covered). Unfortunately, I couldn't measure the accuracy of the NHB-18NS Mk.2's RIAA EQ (footnote 4).

The NHB-18NS Mk.2's built-in phono section is not the equal of the CH Precision P1 or the Ypsilon VPS-100 Silver Edition or other standalone phono stages. It's neither as transparent nor as dynamic as either of those named, but they are dedicated phono preamps that by themselves cost in the neighborhood of the darTZeel (the CH, at $31,000 without X1 power supply) or a lot more (the Ypsilon, at $65,000). However, the Mk.2's phono stage will more than satisfy casual vinyl listeners, and even enthusiasts who haven't been exposed to the best outboard phono stages might be happy: It produced no obvious additive flaws, while presenting well-organized aural pictures against impressively quiet backdrops.

Input options for the NHB-18NS Mk.2's phono preamp can be adjusted via a single toggle switch, under which are two rows of six LEDs each (since the preamp is dual-mono, there's one of these switches for each channel, directly under each phono input, all on the preamp's rear panel). The operating system is devilishly ingenious and, once you get the hang of it, easy to use—unless, like me, you don't have convenient access to the rear panel once the preamplifier is in the rack. In that case, it's difficult to impossible to adjust the phono input, unless you can at least angle the chassis out, after which you can use a mirror to see the LEDs. I tried my GoPro camera with iPhone app, which accepts the camera's WiFi transmission. I thought that was an ingenious idea, but the bright LED lights smeared on the screen; I ended up using a mirror. Still, it's a far easier arrangement than on the original NHB-18NS. I'm going to try using a filter on the GoPro's lens.

As on the original NHB-18NS, each input has its own module—there are no signal-routing contacts, switches, or relays. Selecting an input routes the signal directly to the volume-control module.

I'm not sure if the NHB-18NS's actual signal-passing circuitry has changed—it still has zero overall feedback, small amounts of local feedback at the inputs and voltage gain stages, and only seven transistors in each input module—but I thought its sound had improved.

---

Footnote 1: CH Precision Sàrl, ZI Le Trési 6D, 1028 Préverenges, Switzerland. Tel: (41) (0)21-701-9040. Fax: (41) (0)21-701-9041. Web: www.ch-precision.com. US distributor: CH Precision America. Web: www.ch-precision.us

Footnote 2: You can hear the Nick Culp Quintet's recording of "Division St." here, or stream the 24-bit/96kHz file at the bottom of my review.

Footnote 3: darTZeel Audio SA, 2 Ch. Louis-Hubert, CH-1213 Petit-Lancy, Geneva, Switzerland. Web: www.dartzeel.com. US distributor: Blue Light Audio, 4160 SW Greenleaf Drive, Portland, OR 97221. Tel: (503) 221-0465. Web: www.bluelightaudio.com

Footnote 4: See fig.12 at www.stereophile.com/content/dartzeel-nhb-18ns-preamplifier-mk2-measurements.