The AE2270 is a discrete operational amplifier designed specifically for sound. It is the result of several years of experiments and construction of prototypes of different designs and with different installation technologies. It offers an inarguable superiority to any integrated operational, specifically sold for audio or not. Intrinsic advantages of a discrete design are that it offers less noise that an integrated one, a very higher capability of load handling and specifications that can focus in which is required for the excellence in the treatment of audio signals, as opposed to integrated designs, due to its own process of manufacturing, can do.
AE2270 has been designed to be feed from symmetrical lines with a wide range of voltages, exceeding by large the integrated one, which allows using it in power amplifiers of moderate power (up to 60 W per channel on 8 ohm) voltage gain stages. In addition, it also allows it because, due to its carefully internal design, it has an excellent PSRR and supports to be fed from unregulated supply lines, as usual in power amplifiers, perfectly.
The low noise feature, which is given by discrete design input on BJT technology, makes it perfectly suitable for use in sensitive to noise applications, with high gain, as phono stages or microphone preamplifiers. In any small signal application its performance is excellent.
Its capacity of large loads handling with low distortion has been another of the goals fixed in its design process, having an output stage with large current capability, not available today in integrated operational amplifiers, that allows it to remain in class-A practically under any normal use circumstance, eliminating all distortion produced by crossover and switching procedures.
Construction of a headphone amplifier with the AE2270 was done in a zero output impedance circuit topology, and could handle perfectly headphones of 32 ohm, average efficiency, to a normal level of listening, and above this, with a THD less than 0.01% in the audible band.
This, which represents the extreme case, taken to the cable management, such as an audio equipment output stage, as is in our The Box, is an excellent capacity to avoid the influence on the signal of cable parasitic characteristics.
This also gives an idea of its enormous stability, which allows unity gain configurations without adding any external component. However, the AE2270 is manufactured with two additional terminals if, under some circumstances, an external compensation was required.
That’s stability, flexibility and fidelity. That’s quality. That’s AE2270.
And this stability is achieved without detriment of “slew rate”, being the AE2270 a very fast amplifier as well as stable, with a square signal rise time that multiplies widely the requirements for a faithful reproduction of sound signal from the most demanding source, either a microphone or a digital source.
In addition, the output stage of the AE2270 is protected electronically against overcurrent, while input is against overvoltage.
Regarding to physical implementation of the AE2270, the following technological considerations were used:
- Five standard input and output terminals: not inverting input, inverting input, output, positive rail, negative rail, and two terminals for external compensation, for optional use when required. This makes it easier for system manufacturers.
- Completely in technology SMT, that provides:
- Very short signal paths.
- Good thermal coupling.
- Designed looking for the shortest possible and extremely wide tracks: internal impedance due to the PCB negligible.
- Components selected carefully and with maximum demand:
- Thin film resistors of 0.1% tolerance (25 ppm) in critical functions.
- NP0 / C0G capacitors for compensation.
- Low noise transistors.
- PCB with 70 um thickness copper (rather than the standard of 35 um), that provides, again, negligible tracks impedance.
AE2270 is encapsulated on one side by a coating of hard epoxy resin which, among other things, improve thermal coupling of components as well as dissipation.