Burr Brown OPA627AU Op Amp

written by: Ferdie A.

Introduction

In any new venture, there should always be a test phase where you get to come up with a list of pros and cons, filter everything down to what’s beneficial, and assess if it’ll work or not. So hopefully, this one works the first time around. If not, I’ll have to redo everything from scratch - something that I usually do not look forward to.

Disclosure

This review was only made possible via the assistance of several individuals from the Walnut and Zishan Enthusiasts Facebook group. I did not receive any form of payment from Burr Brown, Onkyo, and Walnut in exchange for this review. The Burr Brown OPA627AU Op Amp and Walnut V2S DAP have been fully paid for and are currently owned by me. The Onkyo E700M IEM was purchased by Edwin, the co-founder of Listening Notes.

About me

I have a simple musical background. I played classical and electric bass guitar in high school, and then eventually moved onto playing electric blues guitar after college. I used to have a large collection of boutique musical instruments and other related gear. After several years, I had to take a different path from music and focus on family. Recently, I joined an online audiophile group that helped put my love for music back on track. 

Musically, I prefer listening to mostly classic rock, blues and instrumental jazz fusion music. From time to time, I also listen to alternative rock, progressive metal, and meticulously chosen pop songs.

Reviewing the Basics

• Packaging/Accessories

I received the Burr Brown OPA627AU from a group buy event that was hosted by the Walnut and Zishan Enthusiasts audiophile group on Facebook. The SOIC was pre-mounted onto a red PCB that had DIP8 legs. It was small enough to fit in and close the lids of the Zishan and Walnut DAPs.

• Tech Specs

Amplifier Type - General Purpose

Number of Circuits - 1

Output Type - /

Slew Rate - 55 V/µs

Gain Bandwidth Product - 16MHz

Current - Input Bias - 2pA

Voltage - Input Offset - 130µV

Current - Supply - 7mA

Current - Output / Channel - 45mA

Voltage - Supply, Single/Dual (±) - 9 V ~ 36 V, ±4.5 V ~ 18 V

Operating Temperature — 25°C ~ 85°C

• Sonic Review

• Gear Used - Walnut V2S with the Burr Brown OPA627AU pre-mounted on PCB DIP8; Onkyo E700M with stock cables

• Track Used - Chris Jones - No Sanctuary Here; FLAC 16-bit 44.1kHz 

• Track Sample - https://www.last.fm/music/Chris+Jones/_/No+Sanctuary+Here

• Track Highlights - There were a lot of highlights throughout the track, but what I found to be consistently challenging the overall quality of the op amp are the repeating riffs and fill-ins that play simultaneous deep bass lines with the 2nd voice’s deep rumbling hums, guitar string harmonics, and the tambourine played every 4th quarter note. This was played almost throughout the track, which I believe held the whole character of the song’s rhythm. In essence, I was engaged through all the low, mid, and high frequencies without feeling left out or waiting.

• Highs - The details on these were quite articulate. Each pass on the high hat, ride, and crash cymbals, as well as the higher-octave notes on the guitar and keyboards were crisp and detailed. This was also further enhanced with sparkling highs that, from time to time, broke into some acceptable sibilance.

• Mids - Vocals were pretty much upfront and were not pushed back by the low end. These were thick and still retained its transparency.

• Lows - There’s a tad more bass on here compared to the Philips NE5532N. The decay is fast, but is still long enough for you to feel and identify it.

• Soundstage - The width just has enough space for you to have a pretty good image of how the stage was set up. There’s very little difference between the V2S’ stock NE5532P; I daresay just a tad wider. There was also enough height to prevent simultaneous instrument parts from sounding muddy. Unfortunately, I love wide stages. So this was quite a let down in my case.

• Instrument Separation - This definitely had better instrument separation compared to the NE5532P and NE5532N. There was more than enough space in between instruments for proper identification.

• Other Observations - Compared to the Philips NE5532N, the OPA627AU had more volume gain. The OPA627AU was also natural sounding. Its transparency is certainly true to the track being played. It’s more analytical than it is musical due to the details and definition it provides.

Overall Musicality

Choosing your gear to reproduce your favorite song’s original sound is a very significant and exciting venture. The OPA627AU did a pretty good job of being convincing enough to tell me the story of the track. Good enough to actually make me feel engaged enough to think about the song’s story which explores the issues of inequality and immigration using the birth of Jesus Christ as reference without ever sounding religious.

Overall Imaging 

I had no issues imagining where everything was. The track was not too busy and was engineered masterfully, which allowed it to be used by American live mixers to test and check their stage PAs. Now, did I find any issues relating to missing instrument parts? So far, I found no issues with those during the playback through the OPA627AU. The egg shaker and tambourine took care of the percussion, but the bass and acoustic guitar were professionally played to help fill in the blanks within the overall mix by using a variety of musical techniques like consistent harmonics and dynamic picking within the center and right sides. The keyboard section did a great job as well of making sure the left side of the mix isn’t left out. The main singer was centered and well-within range to not sound like they’re singing too close to your face but far enough for you to hear what they wanted to say. One of the stars of the track is the back-up singer’s low-end hums who makes sure the whole song’s stage was felt and understood. 

Summary and Recommendations

The OPA627AU is a good op amp. Given the right amount of supplied power, I believe it can open up a bit more and provide more width on stage. So I’d suggest using this with larger living room-type amplifiers and music players to be able to maximize it’s inherent potential. If you like details and getting right into the mix with how each instrument was played, this is an op amp that you should consider.