Micromega IA100 Integrated Amplifier

The concept
IA100 was designed to be ergonomically intuitive and the interface easy to use, thus enabling smooth transition when switching from one model to another in the Micromega range. Made in France entirely out of galvanized steel, the role of the amplifier’s frame is to provide a stable and rigid base for the various electronic boards. It also protects all of the electronic circuits against external electromagnetic disturbances and high frequency exposure, which are very common in today’s environment. The aluminum front panel adds a special touch to all of the models of this range, providing an impression of elegant soberness, where minimalism and user-friendliness combine harmoniously. A digital rotary encoder, driven by the unit’s micro-controller, allows you to set the volume level or balance as well as other parameters such as headphone output level which can be set independently from the master volume level. All connectors are Gold plated and the reference grade WBT loudspeaker connectors take banana plugs as well as stripped cables of up to 10 mm² cross-section. The aluminum anodized top cover, which comes in either black or silver, matches the front panel perfectly. The brushed effect of the front panel gives the product an unrivalled distinctive touch.

The power supply
If there is a type of audio equipment whose quality depends almost entirely on its power supply, it’s the integrated amplifier. Indeed this type of equipment requires very detailed attention in this regard because several types of signals are treated at the same time and inside the same enclosure: small amplitude weak current signals and high amplitude strong to very strong current signals if the loudspeaker’s impedance is low. This is all the more true in our case as all MICROMEGA’s integrated amplifiers are equipped with a Phono input, making this issue more delicate still. The Phono input requires extremely optimized power supply filtering because in the Phono section, the signal has to be equalized according to the RIAA standard curve.

Taking into account these requirements, we opted for two types of transformer: one R-Core for all preamplification stages and one toroidal, exclusively for the power section. The toroidal transformers are quiet and offer a very favorable power/dimensions ratio. In addition, their two-wire construction allows a perfect alignment between windings, which is a necessary condition for good common mode rejection. This transformer was specially designed for the IA100, which required a very high dynamic capability in order to guarantee vitality and transparency of the musical message. It should be remembered that in a high fidelity amplifier it’s not continuous power which is most significant but the instantaneous power that the power supply is capable of delivering and consequently the amplifier’s power stage. Equally, the speed with which the power supply can react is significant in terms of final quality obtained and therefore must be considered when a product is in the design stages. MICROMEGA’s development team, using powerful simulation CAD software, designed a custom transformer for the IA100 and its characteristics perfectly match this amplifier providing more than 25 A and more than 200 A peak intensity.

The input board
IA100 shares the same input card as the two other integrated amplifiers in this range. To fulfill current requirements, IA100 offers the following inputs: PHONO, AN1, AN2, AN3, AN4 and iPod/iDok. In addition there are other features, such as a monitoring loop, a PROCESSOR input, a SUB input and output to allow 2.1 functionality as well as separate control over the Sub out in both modes. Particular care went into designing the phono input and its stage which accepts moving magnet cartridges. Although CD invaded the planet, many audiophiles remain extremely attached to their vinyl record collection and it appeared essential to satisfy them too. The circuit used has its own regulated power supply to eliminate interference with the other active circuits as much as possible, thus offering the most faithful RIAA correction possible. The line level signals are switched using high quality relays and buffered with Jfet opams to avoid loading the source. The monitoring loop is independent and the tape output is buffered to avoid the well-known phenomenon of distortion. The headphone output, situated on the front panel, uses a small stereo power amplifier capable of delivering enough current to avoid low impedance headphone problems and providing the 32 to 600 O headphones with superb dynamics. Very often the headphone output is only there because it has to be, but works with a poor quality amplifier. MICROMEGA, conscious of the fact that many music lovers like listening with headphones, decided to fully satisfy them and avoid the need to acquire an often extremely expensive separate headphone amplifier.

The power amplification
After many hours of listening to various type of music, MICROMEGA selected 4 LM3886T modules in parallel to serve as the IA100’s power modules for the power section. Although this choice could be questionable at first glance, the listening results in this particular configuration are astonishing. As long as the speakers selected do not show very low impedance and very low sensitivity, IA100 is capable of reproducing all types of music effortlessly, while truly respecting the spirit of the musical content. The specifically designed heat sink, using pressed fin technology, keeps the modules under a very reasonable temperature range in all circumstances. All audiophiles know all too well that high temperature is a serious enemy, especially for electrolytic capacitors that dry out after a while and fail.

A subtle balance
IA100 has the ability to attract the listener into the world of transparent musical reproduction where the system disappears leaving the stage to the musical content.