Details about CEC AMP 3300 CONTROL / POWER AMPLIFIER LEF SINGLE ENDED CLASS A POWER AMPLIFIERSee original listing
For parts or not working
Mar 04, 2012
[ 12 bids ]
SE Michigan, United States
|Condition:||For parts or not working||Channels:||2 Channel|
For Parts or Repair
CEC AMP 3300
Pure Class A Single-Ended Amp
The AMP3300 is a Class
A amp that features an extremely pure single-ended circuit
with each one single
transistor for the non-inverting and inverting lines,
that handles all music signal processing.
Earlier Class A amps were inefficient, had extremely low output and generate considerable heat when operating,
but the AMP3300 uses a load effect free (LEF) circuit to successfully combine high-efficiency power with high-quality pure Class A amplification.
The primary technology of the LEF is to avoid various sources of nonlinearities.
CEC's Original LEF Circuit
The AMP3300 features
CEC's unique load effect free (LEF) circuit to avoid completely all factors that
result in deterioration of sound quality.
The LEF circuit makes possible
pleasing and detailed playback as well as a high efficiency.
Every amplifier should
be a perfect voltage source in theory, while the current into the speaker is
likely out of phase in relation to the voltage.
The phase relation varies with the frequency and is even dynamically moving. NFB amplifiers are sensitive to this matter, specifically to the dynamic changes.
The LEF's current control
stage is not linked to the signal voltage,
and just checks the current requirement that depends on the speaker load without "knowing" about the phase relation to the voltage.
This "phase independent operation" is an important
reason for the obvious drive ability as well as sound quality.
The AMP3300 also has an automatic bias adjust function for stable signal processing.
Fully Balanced Signal Processing Circuit
The AMP3300 adopts a
full-balanced circuit design to achieve extremely high-speed and low-distortion
Unbalanced inputs are converted to balanced in the very first stage of the amplifier with no deterioration of sound quality,
in a fully balanced output signal that drives the speakers.
In addition, the left and right signals are processed in circuits divided into two layers to ensure channel separation and a high-level stereo image.
IGM Volume Control
The newly developed
Intelligent Gain Management (IGM) system is used to minimize signal loss during
Sound volume is adjusted by controlling the gain itself with
a knob on the front panel.
The input signal is not degraded by any mechanical volume resistor or CMOS device.
As a result of this, lowest noise, low distortion and highest dynamic performance has been achieved.
The AMP3300 has an LEF
circuit that makes possible extremely stable and realistic amplification, and
since a NFB loop is fundamentally unnecessary in the signal path,
shortest-possible, truly straight signal route is achieved.
The AMP3300 is a completely feedback-free power amp in the signal path that can express
all data perfectly with a single voltage amplification and a single current amplification.
Numerous Input and Output terminals
The AMP3300 has four
conventional RCA input terminals (unbalanced) and one XLR input terminal
enabling it to connect to high-quality products with balanced
outputs such as CEC's CD5300. In addition,
the AMP3300 can be connected to a
such as tape recorder as well as active sub-woofer.
The speaker outputs
are spring-loaded terminals that are simple to connect the cables,
but not come loose easily.
Rated output: 2x 60 on 8Ω, 2x 100 W on 4Ω
Frequency response 0.2 Hz to 80 kHz - 3 dB
Gain: 22 dB / XLR, 28 dB / RCA (max. volume)
Total harmonic distortion: 0.025% / 50 mW
Signal to Noise ratio: 102 dB (1W/8 Ω)
Channel separation: > 100 dB at XLR output, > 90 dB at RCA output
Input terminals: 1x balanced XLR, 4x unbalanced RCA
Output terminals: Tape rec. (RCA), speaker
AC power voltage: 120 / 230 V / 50 / 60 Hz
Power consumption: min. 32 W, max. 300 W
Dimensions: approx. 435x100x360 mm (WxHxD)
Weight: 9,2 kg
Originally sold for $975
LEF technology: The future just begins!
Avoiding a mistake instead of correcting a mistake
Distortions and other sound degradations of amplifiers are due to one main reason: The signal is
running through the non-linear characteristic of transistors or tubes. (Other distortion sources,
like poor power supply and component parts, are avoidable by proper engineering.) Triode tubes,
pentode tubes, FETs and transistors have different characteristics, but one common fact: They
are all non-linear! If their characteristic would be linear, it would be easy to build good sounding
The common way to reduce measurable distortions is negative feedback (NFB). At the first look
this method seems to solve the problem, but only for static test signals, not “random” music signal
– looking good on measurement equipment and paper, but with the usual limitations in sound we
all got used to.
As there are no common ways to test short time (transient) distortions, which happen during fast
signal changes, most engineers assume they don’t exist. Prof. Mati Otala developed a way to
measure TIM – Transient Intermodulation, which this is only a small part of the whole story.
Carlos Candeias succeeded in proofing these short time distortions, which origins from NFB
limitations. As a consequence the development of amplifiers without negative feedback, as well
as very low dynamic and static distortions was initiated. (There are already amplifiers without
NFB on the market, but with sound influencing distortions.)
LEF avoids degradations of sound instead of “correcting” it afterwards.
The breakthrough of LEF circuit is: The signal transistor does not pass through its voltage
characteristic Vce nor the current characteristic Ic.
Passing the voltage characteristic is avoidable by using floating cascode circuit. This is known,
but causes s loss in efficiency and power when using traditional circuitry.
As the signal transistor in LEF circuit does not handle the current requested by the speaker, loss
in efficiency is negligible.
LEF’s most important progress is splitting the handling of the loudspeaker’s current request from
the music signal voltage output stage!
LEF means load effect free. This means: The signal transistor is not loaded by the speaker’s
current request, because he has strong current handling “assistants” – thus no sound
degradation effects due to the load happens.
With today’s common amplifiers it is easy to hear whether it sounds like an airy ballet dancer or a
heavyweight bodybuilder, because the music signal has to pass the more or less “heavyweight”
In LEF technology the fast, airy and delicate signal transistor and the heavyweight current
assistants work, supporting each other. However, the current assistants are not “allowed” to take
part of the signal voltage. This means: The signal transistor does not pass through his current
characteristic Ic. The load, usually the speaker, “sees” only the signal transistor, but no “current
assistants”. This is due to the signal transistors very low output impedance, combined with the
very high output impedance of the “current assistance”. In case of some small current
imprecision that may occur, the “current assistants” are safely “overruled” by the signal transistor.
Unlike usual amplifiers the LEF amp sounds like unlimited power, as long as it works within the
designated power range; combined with speed and colourful elegance.
Volume control -- ( IGM - Intelligent Gain Management )
The non-feedback LEF circuitry allows a new way of volume control. Instead of losing more of less
signal quality IGM increases the sound quality.
An IGM amplifier varies the gain through the whole range of required music volume, without
wasting any music signal. As a result IGM achieves higher a signal-to-noise ratio, higher voltage
amplifier stability and therefore better dynamic performance, stable stereo image and more power
One channel does not play, the other produces the most incredible sound!
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