Burr Brown OPA627AP Op Amp
Having used a Net Audio modified Quad 405-2 for the last twelve months complete with their excellent Dual Mono Power Supply, I was interested to learn that there was a superior op amp available for each of the Quad 405's amplifier boards than the one Net Audio upgrade as standard, the Burr Brown OPA604AP Op Amp.
The Quad 405-2 Amplifier I have has also has had new output transistors, and I have upgraded all the internal wiring using silver plated cable for the power wires and solid silver cable for the line outputs, so I was curious whether the Burr Brown OPA627AP Op Amp could really make that much difference. Trawling through the audio forums it was obvious straight away that the Burr Brown OPA627AP Op Amp was a very special op amp indeed, an ultra low noise op amp ideally suited to audio purposes, although there were plenty of posts about people being unable to differentiate between the sound quality of the Burr Brown OPA627AP Op Amp and cheaper variants such as the Burr Brown OPA604AP Op Amp.
Now don't get me wrong, the Burr Brown OPA604AP Op Amp is a very high quality op amp indeed and compared the original LM301A and TLO71 op amps used by Quad in the 405 and 405-2 offers far superior sound quality. Before I continue though I should stress that while the Burr Brown OPA604AP Op Amp costs around £2, the Burr Brown OPA627AP Op Amp is about 6-7 times more expensive but a £25-£30 upgrade to a Quad 405 is nothing really so I thought what the hell.
The Burr Brown OPA627AP Op Amps were ordered from RS Components and it was an easy 5 minute job to replace the Burr Brown OPA604AP Op Amps given that Net Audio fit very high quality gold plated turned pin IC sockets to the Quad amplifier boards meaning an easy change of chips.
Well all I can say to those people who cannot appreciate the superior sound quality of the Burr Brown OPA627AP Op Amp, either their system isn't up to it or they are deaf. It was evident straight away even before a proper burn in period that the Burr Brown OPA627AP Op Amp was able to extract more detail from the most complex of mixes, instruments sounded more realistic and had their own space around them, vocals had more air to them and all together the sound was more believable and more enjoyable.
As the amp warmed up and the Burr Brown OPA627AP Op Amps began to burn in, the sound just got better and better, all together money well spent and an upgrade I can recommend to Quad 405 listeners 150%. Because of the design of current dumping amplifer like the Quad 405, the quality of the op amp has a huge bearing on the final sound and an ultra low noise chip like the Burr Brown OPA627AP Op Amp can only be the way forward.
The Burr Brown OPA627AP Op Amp is a truly exceptional component and a suitable building block for any audio project, and one that is well worth the extra outlay if you can find a stockist.
This entry was posted on Wednesday January 3rd, 2007 at 10:19 PM and is filed under Tweaks. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response.
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1 Response to "Burr Brown OPA627AP Op Amp"
Chris daly Says:
October 25th, 2008 at 4:38 AM
Indeed the opa627 is a very good opamp, however its just too good for the 405. A better choice in the 405 circuit is the Analog Devices AD 825. The opa627 in the 405 just cannot do its thing - its being held back probably by Zener Diode power supplies, DC feedback summation nearby and attenuation prior to TR2 - all necessary to keep the 405 circuit running as Quad intended.
The AD825 however really works well, sounding open and precise in the 405 circuit it seems to get over the other duties its being asked to do.
The opa627 is much better in I/V stages ( output stages ) of CD players here it really works well.
Cheers / Chris