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The bandwidth of the MIPA output transformers goes up to 95 kHz

 

The MIPA is  - as the name suggests - designed for pure battery operation. When fully charged, moderately efficient speakers could be driven for eight to ten hours, higher efficiency ones even longer. Now you may say, other manufacturers have already had this idea. True, but that's not everything of course.

 

Here, the house specialty is also the transformer, an essential part of the circuitry. The signal first passes through an input transformer which additionally splits the signal into plus and minus. From there it goes to the MOSFET amplification stages, one for plus and one for minus. The transistors are mounted on a small spring-mounted circuit board. This is the only place that is not hand wired.

 

An interesting side note: The electrolytic capacitors on the circuit board are stripped, meaning the plastic cover on which the data and polarity is stamped, has been removed. This is responsible for quite bit of sonic improvement.

 

The signal goes from the MOSFETs through another transformer to the output jacks. This will optimize efficient signal transmission to the speakers.

 

The bandwidth of the output transformer goes up to 95 kHz. The transformers are meticulously wound in-house using proprietary techniques so that they greatly minimize thermal distortion. Some listeners are probably concerned when they hear that there are transformers in the signal path. You should remember, however, that professionals in the recording world use transformers everywhere and therefore not one "transformer-free" recording exists. The transformers employed have a specially selected core material of 035 grain oriented silicon iron.

 

Meticulous attention is paid to the signal path by connecting all components with in-house silver wire. In addition, most components are not bolted, but clamped between the top and bottom of the unit with wooden columns and felt pads, thus damping them from vibrations.

 

But if that is still not enough, there is much more to the design. The basis for this was written in several articles in the French magazine “L'Audiophile” in the late 70’s. Here, a French rocket scientist with the pseudonym Héphaïstos, examined the phenomenon of thermal distortion in transistors. This phenomenon does not seem to be very well known today or just may be ignored. In this extremely interesting essay, not only basic, but very complex circuits are described in which a multitude of semiconductors mutually try to compensate for this thermal distortion. Audio Consulting take a different path and try, on one hand to produce less distortion by using very simple circuits, and on the other hand to compensate for the rest by using specially wound transformers. It is certainly striking that the equipment remains cold even after many hours of operation.

 

To switch the unit on, the main knob has another special feature: besides "on" and "off" there is also a middle setting, which is always engaged briefly when turning on the machine. In order to limit the power up current, it is first sent through resistors to the capacitors - only when in the "On" position receiving full voltage. This protects the contacts of the ELMA switch from increased wear and tear.

 

The amplifier comes in Stereo and Mono versions. The Stereo delivers 30 watts and the Mono version delivers 120 watts, both respectively into 8 ohms with 4 and 8 ohm taps.

 

The above commentary from TEST 02.05.2013 by  JÜRGEN SAILE of HIFI STATEMENT, Germany.

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