For me, the award-winning Yamaha A-S500 was something of an eye opener. It was one of my first modern hi-fi amps – save for a couple of previous budget amps, a Cambridge Audio A5 and Sony TA-Fe370. While my previous amps and systems had given me many, many hours of enjoyment, it was my A-S500 that inspired me to build my first serious hi-fi system – a system in which cables mattered, a proper rack replaced the usual stacks of gear, and the speakers are taken down from the walls and positioned for true stereo sound.
Fast forward a couple of years, and the A-S500 moved onto a new home, and was replaced. However, that amp is one I’ll always remember and look back on fondly. Naturally, when Yamaha announced a successor to the A-S500, the A-S501, I jumped at the chance to check one out and asked for a review sample.
The A-S501 shares a similar design to its predecessor – it’s a large amp, with a thick aluminium faceplate and a set of large vertical controls dominating the middle of the front panel. However, the A-S501 aims to bring the previously all-analogue A-S500 into the modern digital age, incorporating a built-ing DAC in place of the previous iPod dock connection. The DAC employs the Texas Instruments PCM5101, and supports resolutions up to 24-bit, 192KHZ.
The amps analogue roots haven’t been forgotten, however – the A-S501 boasting 5 line inputs (including 2 recorder loops) and a moving magnet phono stage. The power output of 85W per channel (into 8 ohms) remains from the previous model, as does the impedance selector – which adjusts the amps power supply to provide more power for low-impedance speakers.
That power supply includes a custom power transformer and 2 custom-made 12000UF block capacitors. The A-S501 features separate power supplies for the analogue and digital sections.
2 Direct signal path speaker relays and an optimised circuit layout offers the shortest possible signal paths, while Yamaha’s pure direct mode allows you to bypass the tone, loudness and balance controls and the input buffer amp shortening signal paths even further.
The A-S501 benefits from Yamaha’s ToP-ART (Total Purity Audio Reproduction Technology) – a symmetrical input to output design, with both left and right amplifiers organised symmetrically resulting in a pure signal whilst minimising distortion and crosstalk between channels. In edition, the chassis incorporates ART (Anti-Resonance and tough) technology, including a solid base and supporting central bar to minimise the effect of vibration on the sensitive electronic components.
Packaging
The A-S501’s packaging is just as we’ve come to expect from Yamaha. The amp, wrapped in a foam-like cloth material, sits inside a strong box held in place by thin blocks of polystyrene. Along with the amp, you’ll find the remote, some batteries and some documentation. It’s simple, and effective.
First impressions
Weighing in at roughly 10.3KG, the A-S501 offers up a weighty, substantial feel as you lift it from its packaging. It feels solid, too – with no flexing as you move it around. That top cover, with its huge cooling vents is supported by the internal central bar, denoted by the top screw near the front panel. It keeps the cover firmly in place and reduces resonance – the enclosure emitting only dull thuds when tapped. The vents are also most effective – the A-S501 remaining cool to the touch even when pushed hard with difficult speakers.
The front is distinctly Yamaha. To the right, the large textured volume control dominates much of the end of the front panel, accompanied by a smaller but similarly designed rotary dial for source selection. LEDs surround the source selection dial, illuminating the currently selected source – while the pure direct switch sits discretely beneath the 2 controls.
That volume control is motorised, allowing you to operate it from the remote control. It’s also electronic – the volume a resistor-ladder type control with resistors switched in and out of circuit by the A-S501’s microcontroller as the analogue potentiometer is operated. This method, also used in Yamaha’s top of the range A-S3000, results in far greater accuracy at low volumes, better channel balance, and less crosstalk between the left and right channels.
In the middle, 4 large vertical dials offer controls for bass, treble, balance and variable loudness. Yamaha’s unique variable loudness technology reduces the mid range frequencies, and adjusts the bass and treble frequencies accordingly, compensating for the human ear’s loss of sensitivity at low frequencies. It’s useful for improving the sound quality when listening at low volumes in the background or at night.
To the left sit a power button, an IR receiver, a headphone jack and a speaker selector, allowing you to switch between the 2 pairs of output terminals. The A-S501 supports bi-wiring or the ability to run 2 pairs of speakers. If used in this configuration, each pair must be 8 ohms or higher. You can also disable the speakers entirely if you wish – and they’re automatically disabled when headphones are connected.
The record selector found on the previous A-S501 is no-longer present – and is a disappointing omission, as it was a feature i used often. A sticker covering the left-and-side of the front panel extols some of the A-S501s virtues – to me, this makes the amp look rather cheap and were this my amp, it would’ve been immediately removed.
Let’s talk for a moment about that power switch. It’s a hard power switch – shutting off the power supplies completely when the amp is powered off. However, the amp does offer a less than 0.5W standby mode, which you can toggle on and off from the remote. The A-S501 also offers an automatic standby feature which will power off the amplifier after a period of inactivity
yamaha are a company who continuously impress me with their attention to detail – and the A-S501 is no exception. The controls feel beautifully smooth, the tone, balance and loudness controls snapping into their flat positions with a sharp metallic click. The volume control is little sensitive at low volumes, but this is easily compensated for with the variable loudness control.
Switch to the back, and the most obvious feature is the permanently attached power cable. I’m not a fan of fixed power cables – as damage to the cable means you’ll need to open the amp up to replace it with an appropriate cable. It also makes installing and removing equipment from your rack more difficult than it needs to be – so a plug-in cable would’ve been much nicer to see here.
The aforementioned impedance selector switch accompanies the large speaker terminals, which can accept bare wire or banana plugs. Of course, no Yamaha would be complete without fiddly end caps pushed into the speaker terminals, which require removal if one wishes to use banana plugs.
In the middle, you’ll find inputs for the built-in DAC, along with a DC input for Yamaha accessories such as the YBA-11 bluetooth adapter. The DAC is limited to a single optical and a single coaxial input – which Yamaha intend to be used for a TV and a blu-ray player. There’s no USB for you computer, so you’ll need an external DAC for that. Personally, I feel that build-in DACs in integrated amps are rather useless – and at this price, you should be investing in an external DAC. However, these digital inputs are infinitely more useful than the proprietary iPod dock socket included with the previous A-S500 – and they allow you to hook up your TV, blu-ray player or even a cheap CD player/streamer for better sound.
There’s a switch to enable or disable the automatic standby feature, and finally a block of analogue inputs and outputs. These include 5 line level inputs, a moving magnet phono stage with ground, 2 record outputs and a single mono subwoofer output. The sub output includes a 100HZ low-pass filter, but for the best results you’ll want a sub with a crossover that allows you to match its frequency response to that of your speakers.
The phono stage is an opamp-based stage. Cartridge loading is fixed at 47K ohms, 220PF – so it will work well with the majority of moving magnet cartridges. While it’s not particularly sensitive, requiring the volume to be raised above that of most line-level sources, it’s quiet, distortion-free and sounds excellent.
The Remote
The remote supplied with the A-S501 is a typical Yamaha offering. In fact, it’s similar to that supplied with the CD-N301 – with a few alterations to the controls and the layout. The buttons are a little small, but despite this the remote is pleasant to use and works well.
The remote also offers a couple of features not present on the front panel of the A-S501 itself – including standby and mute controls, the latter reducing the volume by approximately 20DB when pressed. A second press causes the sound level to gently return to its previous position.
Sound
There’s no drama involved in setting up or using the A-S501. After connecting everything up and pressing the power switch, the amp will take a few seconds to stabilise and come out of protection. Then it’s a simple matter of selecting your input source and turning up the volume.
And, providing you’ve allowed the amp a few days to run in, you’ll be treated to a sound that’s every bit as powerful and authoritative as the original A-S500. However, there’s more of that sound – the A-S501 offering more punch, more power and an obvious headroom increase no doubt thanks to that upgraded power supply.
Even at low levels, the A-S501 manages to convey an impressive level of detail. Its low-level sound is soft and inviting, if a little lacking in bass – but that’s where the variable loudness comes into play. The variable loudness control brings back that low-end power, while allowing you to use more of the A-S501s volume scale.
Want to rock out? No problem – the A-S501 is more than happy to oblige. With pure direct mode engaged, bypassing the tone and loudness controls, the A-S501’s reserves of power can be unleashed. Given room to breathe, so to speak, the A-S501 displays an effortless ability to drive the speakers to ridiculous levels. It’s coherent, too – the amp never appears to struggle, even when pushed hard. While the A-S501 maintains control of the drivers, it’s perhaps not the tightest, most rhythmically adept listen – low end bass notes occasionally slip, and the leading edges of notes can have a tendency to blur into one another.
But what the A-S501 lacks in low end control, it makes up for in the mid range – its beautiful, slightly forward mid range is a treat to the ears, especially with the likes of Norah Jones’, John Mayer’s and Hayley Williams’ vocals.
Sound staging is excellent, the A-S501 managing to convey a decent 3-dimensional stereo image. It’s also very coherent – its ability to separate the layers of a complex mix was a trait of its predecessor that I’m pleased to see the A-S501 has inherited.
The A-S501s headphone performance is impressive. The sound stating does shrink somewhat compared to the speaker outputs, however that coherence is still there. It’s a joy to listen too, and keeps you hooked for hours on end.
And lastly to the built-in DAC. It’s a decent effort, very warm-sounding with high levels of detail. There are no fancy digital filters, despite them being offered by the PCM5101 chip. But that’s no bad thing – those filters often have such a subtle effect on the sound that finding the best filter is often nothing short of maddening. The A-S501’s DAC is about as good as you’d get for the price, and will put many stand-alone offerings to shame. It sounds a lot like the digital section found in the CD-N301 streamer – and that’s certainly no bad thing.
Summary
Another fantastic effort from Yamaha, the A-S501 is a worthy successor to the previous A-S500. While the A-S501 offers several advantages over its predecessor, including a built-in DAC, upgraded components and revised circuitry, it’s still the same amp we all know and love. It’s big, bold and powerful sound is instantly likeable, it’s flexible enough to integrate well into almost any system, and it’s built well enough to provide many, many years of musical enjoyment.
Were I to make any changes to this amplifier, they would be minor. A detachable power cable would be a nice touch, and I’d like to see the record output selector re-introduced – an especially useful feature given that the A-S501 offers 2 tape loops. However, with an excellent DAC and phono stage on board, and the A-S501 being an impressive analogue amplifier itself, there’s no cause for complaint at the price. Highly recommended.
