Stereo 15W+15W KT 88 single ended amplifier..FROM BRAZIL..


The stereo 88 is based on the model 88 circuit. The model 88 uses two amplifiers with slight assymetries specially connected. The stereo 88 makes these two amplifiers identical simulating the average prefered behavior of the model 88. Unless you have larger rooms this version may work very well in most situations that the model 88 work. 



The most relevant technical features


LM3 -  Low Mu Triode with Higher Real Efficiency Emulator (LMTHREE)

MPS - Matched Power Supply combines high speed and definition with exceptionally low noise

Timbre Lock - The world's first system optimizer.

• Unusually extended frequency response

• No global feedback used to achieve these outstanding specifications  


Timbre Lock - the world's first optimally adjustable amplifier/speaker interface


The stereo 88 has its own version of Timbre Lock. It is somewhat more limited than the full version that is present in the model 88 but it can be extremely effective. The interaction between amplifiers and loudspeakers has long been recognized as being of paramount impor-tance. Very little has been actually done to study it. Almost no one has tried to actually do something about it. After years of designing custom music systems that included the design of mostly single-ended amplifiers and carefully matched speakers, AUDIOPAX has developed a deep understanding of this subject. More importantly, we also introduced and implemented several practical ideas. Timbre Lock will give you the means to adjust your sound to achieve a level of refinement that is the essence of very well matched systems.

Timbre Lock gives you the power of "dialing in" the amplifier behavior that will be best for the system, not just for the amplifier.

Essentially, you can adjust your system to deliver your preference. You can bring vocalists into the room in a more intimate and vividly compelling manner, all at your command. Choose your level of musical articulation, combined with your specific requirements in terms of high frequency smoothness and extension, and how "relaxed" you'd like your music.


The output transformers


They are the "heart" of any tube amplifier. As much as people try to say that it would be better to avoid them entirely, we definitely do not agree. Everything is in the specific details and with output transformers, it's about design and implementation. As our white papers explain, output transformers play a crucial role in creating the amplifier behavior that will result in better overall system performance.

AUDIOPAX output transformers are designed in house and are produced under our direct supervision. They truly represent a new kind of output device. They are much smaller than usual for the same output power. This is done because this is how we achieve our standard-setting performance; not because we want to save costs. Actually, in these transformers the materials cost is almost irrelevant when compared to the labor involved. We wind very precisely almost thirty different coils on the specially treated oriented grain iron core. These exclusive AUDIOPAX single-ended transformers for the stereo 88 deliver a frequency response that's amazing and totally unusual. If we consider just the output stage (rather than the entire amp), using the KT88 tube, they will deliver a high frequency -3dB point at over 110 kHz! At the lower end, we can expect something like -3dB at 14 Hz. These are measurements at 1W RMS / 8 ohms. The power bandwidth and the transformer behavior under power are designed to conform to what our research has proven to be best for interfacing with average medium-to-high efficiency loudspeakers







Max. Power Output p/channel 

   15W RMS at 1kHz in 8 ohms

Frequency response:
   14Hz to 90kHz (-3dB) 
Signal to noise ratio:
  > 90 dB (A weighted) ref. 30V 


Input impedance: 

 215 Kohms
Output impedance: 

 3,7 ohms 

  13" x 9" x 14 " (H x W x D)

Weight: 42 lbs. 





At the stereo 88 was reviewde in August 2003  


"... The Audiopax Stereo 88 reminds me of one of my all-time favorite tube amplifiers. Like the Stereo 88, my old flame owed the lion's share of its success to a fantastically clean and emotionally communicative yet intellectually honest midrange. Its treble was so well behaved and balanced as to almost defy description. Bass was tight and controlled enough that the listener would easily forgive the absent last iota of brute power. The amp? The Audiopax Model 3 integrated "

John Potis, publisher,,




STEREOPHILE Audiopax Model Eighty Eight monoblock power amplifier



HiHI Choice magazine in England has reviewed the stereo 88 and praised as a great sounding amplifier.  


"... Even the source of this single-ended triode amplifier is unusual - not much hi-fi originates in Brazil, but that happens to be the home of Audiopax designer Eduardo de Lima. He's clearly a great thinker, and his website includes a very considered article by him reviewing the state of single-ended valve amp design and its enduring appeal in the face of much superficial objective evidence that its capabilities are limited, not to say hobbled... What's considerably more intruiging, however, is de Lima's claim that his amplifiers can reduce total system distortion. Snake oil? Not at all. In simply numerical terms, system distortion is normally dominated by the loudspeaker. Speaker distortion can be lowered by using an amplifier with very high output impedance, driving the speaker in 'current mode'. The output impedance of most SET amps is not high enouhg to reap the full benefit of that (and pure current drive to normal speakers results in a completely out-to-lunch frequency response), but de Lima points out that an alternative approach is to generate an opposing distortion term which cancels the distortion of the speaker. In other words, the distortion of a SET amp can be 'tuned' to null that of the speaker itself, leaving, ideally, a cleaner spectrum than that produced by such low-distortion tours de force as the 'Super-Fidelity'  models ... "



"... I will start here with the conclusion then. The AUDIOPAX Stereo 88 definitely retains all the magic, enchantment and musicality of the monoblocs which, by themselves, have been one of the most emotionally involving amplifiers I have ever heard in my entire life.

What was present here were the same absolutely jetblack silences that had left me almost in vertigo with the monoblocs. Present too was the startlingly real reconstruction of the harmonic envelope. The highs were clean and extended, floating in the air like clouds on a beautiful spring morning sky.

Fernando Andrette,  Audio e Video magazine, May 2003