Laney L50H - Manual (Page 9)

L50H
OPERATING INSTRUCTIONS
A 50W SINGLE ENDED TRUE CLASS A AMPLIFIER
The new L50H uses well proven preamplifier topology from the existing Lionheart range. However the output stage and power supply are totally new and original to
Laney. The design was evolved in-house from the basics of ideal guitar amplification regardless of cost or technology/material barriers.
This gave birth to a design with its routes in vintage amplification with added contemporary features.
Guitar amplification was born from single ended class A tube radio set designs. These were made very simple to keep costs as low as possible. Power ranges only went
up to about 5 Watts with a single tube. Adding more tubes would only increase the power proportionally i.e. two tubes 10 Watts, 3 tubes 15 Watts and so on.
Guitarists soon wanted more volume and this gave birth to the modern day class A/B push pull amplifier designs. This had the wonderful advantage that, by using two
tubes instead of one, four times the power could be obtained and efficiencies were much higher so lower cost power supplies could be used. This appealed to
manufacturers and became the standard for most mass produced amplifiers with power outputs greater than 5 Watts.
However in the strive to get more power at reduced costs many of the inherent sonic advantages of single ended designs were conveniently forgotten.
The Lionheart range goes back to those original single ended designs and develops them in the way engineers would have liked to, at the time, had cost and materials
not been the overriding factors. The new L50H takes this to extremes that could only have been dreamt of at the time. The L50H amplifier uses pure class A single
ended topology with no less than five parallel specially selected and matched EL34B-STR tubes each delivering 10 Watts.
In pure class A the amplifier requires full power continuously so the power supply and output transformers have to be several times the size to cope with the
continuous power delivery. This does have the advantage that when sudden changes in volume are required they can be handled both instantaneously and continuously
without needing to request more or less current from the power supply. The overall effect of this is amazing transient response throughout the sonic spectrum.
A further significant advantage is the inherent distortion products produced in single ended class A designs. These are mostly low, even order harmonics which always
sound musically correct. Modern push pull designs cancel out even harmonics leaving odd ones which do not generally sound good. The overall effect is that the class A
single ended design sounds warmer and tonally more natural.
Since the single ended Class A output produces mainly pleasing distortion products, very little feedback is required to achieve good performance. A big side benefit of
this is a dramatic improvement in transient distortion and the addition of a natural soft low order harmonic clipping. This gives the amplifier much greater perceivable
headroom and peak power. However the low feedback levels used require a massive ultra wide bandwidth output transformer to avoid adding unwanted distortion
products anywhere within sonic range.
The number of tubes, massive toroidal power supply, and special output transformer all add up to an expensive power amplifier several times the cost of an equivalent
class A/B design.
Play the L50H class A design, teamed up with the matching Lionheart L412 or LT-212 to deliver sound in an airy, almost three dimensional, way that is totally intoxicating.
We think you will agree; a small price to pay for musical perfection.