Whammerdyne Truth, Owner'S Manual

Page: 7 / 16

www.whammerdyne.com
3
The ultrawide bandwidth output transformers are custom engineered for this amplifier and have
the widest bandwidth of any single-ended output transformer, past or present. Tube amplifiers
have gotten a reputation as “midrange” amplifiers. Not the Truth
™
! The response extends from the
deep infrasonic at 6 Hz, to the far ultrasonic at 140 kHz. Although it might seem unnecessary, this
additional bandwidth provides flat phase response in the 20 Hz to 20 kHz audio band.
Why single-ended? One of the subtle advantages of single-ended operation is no zero-crossing
region, either in the tubes or the transformer. The zero-crossing region is where most of the
music is, along with reverberation.
This is where both analog and digital electronics have to be most linear; unfortunately, for most
conventional Class AB amplifiers, the zero-crossing region is where pairs of transistors are
switching on and off, and for tube amplifiers, the region where the magnetization in the core of
the output transformer switches direction. The Truth
™
2A3 amplifier completely sidesteps both
problems by biasing the core of the output transformer with a DC current, and keeping all tubes in
in the most linear Class A region. As a result, harmonic and IM distortion go down in proportion to
signal level, which matches the perception of the human ear.
All key supplies (including B+) are precision regulated, so the operating points of the tubes are
not affected by random line-voltage variations. More importantly, the sonics are not affected by
line-voltage variations or AC line quality. As we all know, the quality of the 60-cycle AC waveform
has gotten worse over the decades, thanks to noise from switching supplies in TV sets and
computers, and the many RF transmitters in modern households. The electrostatic shielded power
transformer of the Truth™ amplifier acts like a filter against these noise sources so they do not
contaminate the delicate audio signal.
We recommend you do NOT use aftermarket power conditioners with the Truth
™
amplifier. Unlike
“one-size-fits-all” power conditioners, the precision regulators of the Truth™ amplifier are custom-
designed to match the operating parameters of the 6DJ8 input tube and the 2A3 power tube.
Last but not least, there’s a pair of relative-power meters that show the percentage of power out
of each channel. At the start of the red marker, there’s about 1 Watt RMS into 8 Ohms, and 3.5
Watts RMS at full scale. Since the Truth
™
amplifier is a zero-feedback circuit with inherently soft
clipping, the range between the 1 and 3.5 Watts is fully usable.
The Left and Right audio signals going to the pair of meters are isolated by buffer circuits,
rectified, and loged to match the meter scaling. Like the VU meters of old, but with wider
dynamic range. So no range switching is required.
The Functional Diagram shows the key features of the Truth
™
amplifier along with the precision
bias settings for the 6DJ8 input tube and the 2A3 output tube. Each channel has its own fully
adjustable set of bias controls, with a custom milliammeter that measures the operating currents
of each 2A3 and each half of the 6DJ8. Although the Truth™ 2A3 amplifier is already pre-adjusted
and matched to its own set of tubes from the factory, you can replicate the factory adjustments.