Zeiler Audio PR-01 and PA-01

The audio reviewer as an explorer? No one is going to believe that. Granted, sitting at home listening to music all day doesn’t make you the Neil Armstrong of hi-fi, but bear with me. A part of the modern audio reviewer’s role is to explore new products and put the best of them in front of the buying public. Such is the case with the excellent Zeiler Audio PR-01 preamplifier and its new matching PA-01 power amplifier.

The days of reviewers as ‘kingmakers’ are – hopefully – behind us all, but there is an understandable conservatism about new product purchases. Because of the price tags involved, buyers gravitate toward established names, thinking the brand is more likely to be around and more commonly known should repairs be needed and that it will have good residuals on the second-hand market. However, this often results in an overly conservative market, where just a handful of big-name brands sell to the same buyers time after time. The problem with this is two-fold; the big-name brand is tied to the requirements of an increasingly ageing community of buyers, and newcomers (either as manufacturers or new buyers) are left out of the equation.

When one amp became two

The Swiss-made Zeiler Audio is a perfect example of how we must collectively think beyond those big, well-established names. The company began with just one product – the PR-01 preamplifier – but quickly added a matching PA-01 power amplifier. Ralf Zeiler designed both products to disappear from the audio chain functionally, leaving just music behind. It’s a goal expressed by many but achieved by few… but I think Zeiler might have nailed it. 

Zeiler’s first product, the PR-01, is a four-input valve preamplifier with four ECC83 valves accessed through two heavy top panels. The three line-level and one MM phono input are all RCA connections. Two of the line-level inputs have Lundahl input transformers, while the third one is 6dB more sensitive than the others. This fourth input helps accommodate older audio electronics (which might have an output voltage of around 1V), where more modern designs like streamers (that can have outputs in the 2.5V range or higher).

The preamp output has a source/tape output for tape monitoring or to connect external headphone amplifiers. There are also ‘direct’ and unbalanced RCA and XLRs with a balanced or unbalanced operation. Direct, as the name suggests, is the high-purity link for those who can keep a short distance between the preamp and power amp. At the same time, the two last connections include an additional output stage for driving super-low impedance power amps or long interconnect cables. The balanced outputs are fed through Lundahl output transformers, with different taps for each option.

Similar style

The newer PA-1 is styled similarly but with fewer controls than the three-knob PR-01. The two 12AX7/ECC83 input valves and the pair of KT150 power valves used to develop the amp’s 10-watt output are cleverly hidden in the side cheeks of the amp itself, allowing for easy, tool-free access and replacement. The amp can take its power on and off instructions from the preamp. Biasing and adjustment aren’t issues with just one power valve per side. The amp is choke regulated and is filled with paper-in-oil capacitors and custom-made Lundahl C-core transformers.

Ralf Zeiler is a hand-wired, point-to-point designer of the old school, and it shows throughout!

Let’s talk about build quality. Swiss-made usually means expensive and well-made, but even by those standards, Zeiler stands apart. Both are built to an impeccable standard, CNC machined out of solid billets of aluminium and then glass-bead-blasted and treated to an ceramic form of anodising… all combine to give this velvety-feeling “none, none more black” amplifier duo the kind of solidity of build and finish that few can match. 

Girthy

The only way it could get any more ‘girthy’ would be if it were built out of bits of Swiss Alp, and to damage that finish would require a chisel, which would be a crime against quality construction! 

The internal construction and parts list is equally impressively solid. Nothing’s left to chance here, and as a result, this feels like a pair of ‘deep time’ products. They are the kind of products you might put in a time capsule to play music of today to future generations. Although why future generations would want to listen to ‘I Am Free’ by Tones And I or ‘Cowboys And Angels’ by Jessie Murph escapes me.

Ralf Zeiler is a big fan of classic Tannoy studio monitors, which goes some way to understanding the genesis of the PA-01. When you are used to the effortless efficiency and scale of big Tannoy designs (or similar), powerful amplifiers become less of a requirement and more of a millstone around the neck of the loudspeakers. You become aware that, in many cases, the higher the power, the less ‘dynamic’ the dynamic range. 

Quality and quantity

Once you begin to parse this design process, your respect for the Zeiler amps goes through the roof. These are simultaneously some of the most cultured and refined-sounding amplifiers and can also give the dynamic force and energy needed to place you in the room with the musicians. Usually, amplifiers that are this refined sounding are ‘beauteous’ with all the raw edges smoothed off. And, equally usually, amplifiers that do this much dynamic energy and excitement are a little too ‘edge of the seat’ for all kinds of musical listening. The Zeiler Audio duo are rare for doing both equally well.

A perfect example of this double-handed approach is the recent Bach Trios on Nonesuch, featuring Yo Yo Ma on Cello, Chris Thile on mandolin and Edgar Meyer on bass. These are pieces of raw energy, and the mandolin gives the recordings a freshness and vibrancy that makes them sound new. Too much ‘gloss’ and the recording becomes too sanitised; too much ‘zing’ and the recording loses its music integrity and flow. But on the Zeiler pairing, this trio sounds magical.

This is, in part, a divine balance, with the sublime elegance of the preamp being the perfect foil for the excitement and dynamism of the power amp. But, such combinations often don’t balance as well as these two do, suggesting that – beyond all things – their shared goals of performing a musical disappearing act drive the Zeiler Audio performance. 

Zen and the art of sound quality

I could get very Zen koan in all this – what is the sound of no sound? – but these amps are more about the realisation than the soul-searching. I played the live version of Donny Hathaway’s ‘The Ghetto’ followed by the studio version of his cover of ‘Misty’, then the live versions of his covers of ‘Jealous Guy’ and ‘You’ve Got A Friend.’ Most other amps do ‘detail’ or ‘sounstage’ or ‘vocal articulation’ well, and the Zeiler duo are no exception in this, but it was the Zeiler duo that made me think how sad it was that Hathaway died so young, and how wonderful that voice was. For someone who has been playing those albums for decades, it is profound to get past the surface listening and go for a deep dive into why I enjoy them so much. 

Granted, the low power output of the PA-01 shapes your options for loudspeakers in a way an amplifier with 20x the power doesn’t. But I’d struggle to find a more powerful amplifier that interacts quite as directly with your music. It’s like getting all the good parts of a single-ended triode design – that sense of effortless, dynamic ‘thereness’ of putting you in the room with the musicians – without the drawbacks of increased distortion (even if it’s benign even-order harmonic distortion, it still adds thickening to the sound) and noise. In fact, with the right loudspeakers, it’s the best of all worlds. And even with not-so-right loudspeakers, as so often your sound is defined by that first watt, the PA-01 makes a very fair case for itself.

The best and worst of us

The shortcomings of both Zeiler Audio amps are more about ‘us’ than the products. The degree of minimalism here might be too much for some to swallow. ‘Shiny, flashy bling’ in Zeiler speak is everyone else’s ‘dark and brooding looking’. This isn’t detracting from the performance or operation; the build quality is fantastic. But if you want indicator lights, Zeiler isn’t for you.

I also suspect the ‘us’ part will extend to that 10W power output. No amount of saying “it doesn’t matter” will reach those who seem set on measuring their ‘audio cred points’ by their amplifier’s output. It’s incredibly frustrating to say how dynamic, powerful, and effortless and how clean an amplifier like the PA-01 sounds, only to have any such sentences excised by someone who has probably never been within 20 miles of the amp. However, that has never stopped people from making their decisions and shouting loudly to defend them.

Self-interest

There is another thing, and it’s pure self-interest on my part. I think the prospective Zeiler Audio buyer isn’t going to come back a few years later to buy a new amp. This is their “I’m done” product that will stop the audiophilia nervosa. And, as an audio reviewer, I don’t want people to do that. I want people to keep returning and buying the magazine or reading the website. 

So I’m talking to the adults here. The ones who aren’t swayed by displays, famous names or on-paper specifications. The ones who appreciate a product that is made to be as uncompromising in sound as in build. The ones prepared to make changes and even sacrifices for the best in sound. It is for them that the Zeiler Audio PR-01 and PA-01 are made. Let the ‘little ones’ play with their shiny toys, changing them with the wind as they get bored; that’s not for you. You want to hear the music as it was meant to be played, without the imposition of a sonic signature from the electronics. And as such, the Zeiler Audio PR-01 and PA-01 are for you. Start saving! 

Technical specifications

PR-01 preamp and phono stage

• Design: Single-Ended Class A Pure Triode
• Inputs: 1 × Phono MM, 2 × AUX / Line Level, 1 × AUX / high sensitivity (for vintage equipment) 
• Input Impedance: 47 kOhm (Phono MM), 1 MOhm (all other inputs)
• Outputs: 1 × Direct Output, 1 × Balanced / XLR, 1 × Unbalanced / RCA, 1 × Source / Tape Output
• Tubes: 4× 12AX7 / ECC83 / ECC803S / E83CC / 7025
• Power Consumption: 16 W in operation, no stand-by
• Dimensions (W×D×H): 37.3 × 36 × 11.3cm
• Weight: 11.6kg
• Price: £29,950

PA-01 power amplifier

• Design: Single-ended pure class A power amplifier
• Power output: 2 × 10 Watt
• Mode: Triode connected, no feedback
• Input Impedance: 470 kOhms
• Output Impedance: 4/8 Ohms or 8/16 Ohms option
• Tubes: 2 × KT150, 2 × 12AX7 / ECC83
• Power Consumption: 180W in operation, no stand-by
• Dimensions (W×D×H): 48 × 36 × 11.3 cm
• Weight: 22.2 kg
• Price: £29,950

Manufacturer

Zeiler Audio

www.zeiler.audio

UK distributor

Digital Audio Consultancy Services

+44(0)7776 511691

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