Net Audio Quad 405-3 Amplifier Update

For the last six months or so Hi-Fi Insight has been listening to a Net Audio supplied Quad 405-3 with their own new amplifier boards which use the best components currently available (at a sensible price)
to greatly surpass the sound quality of the original Quad 405 and 405-2. The op-amp used in these new boards as standard is an Analog Devices AD843 which at around £8-10 per chip is a very high quality, low noise/distortion option.

However I recently decided to swap these op-amps for a Burr Brown OPA627 and see if there was any noticeable difference or improvement in the sound quality. For those in the know, the Burr Brown OPA627 is considered the best sounding IC op-amp currently available, but at about £20 per chip is not cheap and is available as option on the Quad 405-3 from Net Audio, but at a premium price. The general consensus about the Burr Brown OPA627 is that it sounds smooth and detailed but only offers a slight improvement in sound quality compared to cheaper op-amps and a similar performance to the AD843. In fact some readers to this site have questioned whether the original Quad 405 & 405-2 warrant the used of the Burr Brown OPA627 in a circuit plagued by poor choice of other components. This is something I half agree with as my own Net Audio Quad 405-2 only benefited slightly from swapping the standard Burr Brown OPA604 with more expensive OPA627. The sound was definitely smooth and there was slightly more detail, but you had to really listen hard to tell any difference.

Imagine my surprise then, when the Net Audio 405-3 boards were tested with the Burr Brown OPA627. There was an immediate improvement in every area of the sound reproduction and not just the '5%' type as some people say this chips offers. The bass was fuller and more defined, vocals had more air and neutrality, the top end treble was more lucid and sweet. In short, it was like listening to different amplifier.

I then spent the next four hours listening to my favourite tracks and every time, the Burr Brown OPA627 and Net Audio 405-3 combination did not disappoint. It was obvious after listening to a wide range of the music that the improved Net Audio 405-3 boards really allow the Burr Brown OPA627 to achieve its potentially in a way that older Quad 405 circuits just prohibit, and the increased detail and resolution on offer is truly amazing.

The only thing I was left slightly confused about is why the Analog Devices AD843 is used as standard in the Net Audio 405-3, because the difference in sound quality using the Burr Brown OPA627 could never be classed as '5%' improvement, it is more like about 25% and that for me like most people I would imagine is worth the extra £20 outlay. The Burr Brown OPA627 & Net Audio 405-3 combination is simply outstanding and if you choose the standard AD843 based boards, then you are not doing these new boards justice no matter what the rest of your system is.

The good news is if you have bought some of these boards with Analog Devices AD843 op amp, then it is a simple five minute job to replace them that requires no soldering thanks to Net Audio's use of IC sockets on the boards. I promise you will not be disappointed.

This entry was posted on Thursday January 22nd, 2009 at 1:00 PM and is filed under Amplifiers. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response.

Leave a Reply

Name (required)
Mail (required - will not be published)
Website


Security Code