AUDIO Electronic Supply



Announcing a new, exciting, Audio Electronic Supply amplifier. We call it the Super Amp. The new Super Amp started life as the AE-25 stereo amplifier offered for the last few months. Dennis Had of Cary Audio got his hands on the little AE-25 and put in some new Cary technology.

The result is the new AE-25 Super Amp. The first public showing and listening session of the Super Amp occurred on January 23, 2000, in Charlotte, North Carolina at the Charlotte Audiophile Society meeting. The raves and thumbs up approval was overwhelming. Within its power range, the AE-25 Super Amp displays the operating characteristics of a true "high-end" amplifier. Careful design, parts selection and proper circuit topologies contribute to incredible reliability and enjoyment.

For the technically minded, a review of the circuit is in order. The new Super Amp operates in a class A mode. The output stage KT-88 tubes are self biased (auto bias) with a separate 390 ohm non inductive 5 watt resistor and 330 MFD capacitor combination on each tube. This bias network also has a 2 MFD film and foil capacitor bypass. Utilizing this bias network will permit the user to try many different types of output tubes if desired. Some of the choices may range from EL-34Ős, 6550Ős to 6L6Ős. One might even wish to listen with 6V6Ős. All these output tubes will present their own sonic signature. There is no bias adjustment required when listening with these different types of audio tubes in the Super Amp.
The output power is 25 watts in the ultra-linear mode with KT-88 tubes. With a simple wire change at the tube sockets of the output tubes, you may wish to strap the KT-88Ős in the triode mode. This will give you 15 watts of triode power each channel. In the triode mode you will have the sweetest sound from the Super Amp.
The output transformers on the Super Amp are the most important component in the amplifier and have been specifically designed by Cary Audio for use in the AE-25 Super Amp. We have taken an approach in the output transformer design, not dissimilar to the single-ended amplifiers we design and produce. The primary and secondary windings on portions of the output transformer are wound in a bi-filer process with the two inductors interleaving sixteen times. The bi-filer wind (two conductors wound at the same time) will yield the closest balance and coupling of any design currently utilized in vacuum tube output transformers. The E/I laminents used are silicone impregnated hipersil steel contributing to the extremely low loss of the Super Amp output transformer. The above process is similar to the single-ended air-gap design found on the Cary single-ended output transformers.
A balanced drive signal is applied to the control grids of the KT-88 output tubes from the 6922 (6DJ8) driver tubes. These driver tubes sit on top of a pair of 6CG7 dual triodes as a current source. The 6922 tube is configured in a dual differential network that operates in the following manner: The first section of the dual 6922 tube is direct coupled to the input signal from the system preamplifier. The drive signal is amplified through this first section in a class A grid driven circuit with the output signal inverted 180 degrees out of phase at the anode and then coupled to one half of the push-pull bank of KT-88Ős. At the same time the second half of the dual triode 6922 is cathode driven in a grounded grid non-inverting class A gain stage coupled to the other half of the push-pull bank of KT-88Ős. With this network the balance is a perfect plus and minus dual drive signal to drive the final output KT-88Ős in a balanced push-pull configuration. With the simple deletion of one resistor and capacitor at the 6922 tubes socket, the Super Amp becomes a true balanced amplifier that may be driven by a balanced input signal. The Super Amp is offered as an option in the balanced configuration with XLR input connectors

The power supply transformer is designed to operate at a 200% continuous commercial service at the full rated 50 watt output level. The high voltage power supply section is a full wave center tap configuration (not some cheap voltage doubler as used in many competitorŐs amps) to a two stage PI network with two filter chokes, one for each channel. This dual high voltage supply feeds the final output KT-88Ős.

The AE-25 Super Amp is a zero global feed back design. The only thing hooked to the secondary winding of the output transformer is your audio system loudspeaker. You will immediately notice on female voices the lack of syllable sibilance. Music will tend to float between and behind the loudspeakers. You may be hard pressed, from your listening position, to hear any of the music coming from the loudspeaker itself. Bass notes will be full and exhibit sound stage decay. You will be able to play the Super Amp beyond its power rating without discernible clipping. These are just some of the musical benefits of listening to a properly designed tube amplifier without feedback.

A great deal of attention during design of the new AE-25 Super Amp was concentrated on the "overload recovery" ability of the amplifier. The ability of an amplifier to instantly recover from clipping is much more important than is commonly believed. In the power war of amplifier manufactures the mentality is focused on high and then even higher power output to solve the clipping problem. When in reality the most critical aspect is how fast of a recovery an amplifier can achieve after overload. With the incredible dynamics range of live and in turn recorded music, even 2,000 watts of power is not enough. Most of the music being listened to in an average home listening room is only requiring about 3 watts of power. It is on the transients of loud low frequency program material that tremendous signal voltages will appear at the input of the amplifier. It is in this situation that the overload recovery ability of an amplifier is of critical concern. The Super Amp extols its merits in the ability to handle transients and instantaneously recover from brief or even extended overloads. The Super Amp will overload symmetrically at any frequency in the audio bandpass. The Super Amp will also yield faithful reproduction of extremely low frequencies at full output levels. Power transformer, power supply regulation and output transformer design and careful shaping of the overall frequency response curve all play a very important part in the ability of the Super Amp to recover quickly when over loaded. If one were to monitor the high voltage rail voltage (310 VDC) of the Super Amp during soft and also loud music passages it would be found there is no more than a volt or so change from soft to loud passages.

Another technical feature of your new Super Amp is stability. The Super Amp may be operated with no load (without speaker) without damage to the amplifier, output transformer or tubes.

Get ready for years and years of enjoyable music with the new Audio Electronic, AE-25 Super Amp, stereo amplifier.


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Audiophile 519 Brunswick St. Nth Fitzroy, Australia
Due to ongoing development and refinement, specifications are subject to change without notice.