J.C. Verdier Triode Spirit 300B Power Amplifier

J.C. Verdier Triode Spirit 300B Vacuum tube stereo power amplifier for sale, Used (tested and good condition).

The famous 300B was always honoured as much as possible on the range of J.C.Verdier's amplifiers.
It is really a difficult exercise to obtain the best possible musicality with a triode amplifier, because all must be perfect around the tube.
Now we introduce a new improvement in the circuits of the regulated power supply.
It concerns a mounting with 3 additive tubes which tracks all remaining hum, for that reason we call it ”hum hunting circuit”. And more this circuit reduced the internal impedance to quasi nothing.
This improvement adds to the large number of those existent, it leads the Triode Spirit Amplifier 300B to a degree of musicality never yet reached.

Condition: Used in good condition
Brand: J.C. Verdier
Model:  Spirit 300B   
Type: Amplifiers

The amplifier Triode Spirit 300B Luxe is fitted with 9 tubes used in the following function:
- 2 X 300B direct heating power triode
- 2 X 5U4 direct heating power rectifier
- 2 X 6AS7/6080 twin power triode balast regulator
- 1 X 6SL7 voltage amplifier
- 1 X 6SN7 cathode follower/driver
- 1 X 6SL7 Error amplifier and ”hum hunting circuit”.

Power Requirement: 230 V 50 Hz / 117 V 60 Hz or  request
Power Consumption: 300 Watts
Output power: 2x6 Watts
Input sensitivity: 400 m V
Total harmonic distortion: 0,5 %
Vacuum tube used: 2x300B - 2x5U4 - 2x6080 - 2x6SL7 - 1x6SN7
Weight: 30 Kg

Return / Warranty: 30 days

At the origins of low frequency tube amplifiers, the mounting of a single tube was reserved to devices using simple and cheap materials .
By opposition the symmetrical mounting was meaning of perfection and therefore found only on performing and expensive equipment. It is interesting to note that this tendency is now quite opposite. This surprising result has various reasons , two of them are described below.

1. During the 70's Japanese enthusiasts - passionate of music and technique - have discovered the qualities of an old ”WESTERN ELECTRIC” apparatus. This talking picture amplifier designed for small movie theaters was fitted in its output stage with a single tube 300B (WE 91A). The amplifier was not perfect but gave surprising musical results. The dynamics coming from this amplifier seems more potent than its modest rated power let suppose. Working on the matter by improving the power supply to reduce the ” hum ”and using a bigger output transformer, our Japanese enthusiasts gave birth to a new range of High Fidelity single tube amplifier. We have to recognize that this amazing result was ,it seems,a real snook to the technical world.
2. As we know, technical explanations given their value to the musical results have never been approached .For this reason, I ask the reader to take my conclusions only as assumptions. First, we have to evoke a specific aspect: The dynamics . Let us suppose that a musical signal modulates the grid of a tube in a positive direction: the plate current will increase and become maximum. This current flowing in the primary of an output transformer creates a maximum instant voltage at the secondary corresponding to a maximum instant power. When the signal modulates the grid of a tube in a negative direction: the plate current will decrease and arrive to break when the grid is at the cut-off point, the current inside the primary of the output transformer ,then ,becomes zero. At the secondary we recover a maximum instantaneous power, there is no more current.

The attraction carried on by the great audio tridores with direct heating of the filament is growing more and more.
Now, it is not possible to be ignorant of their qualities without being out of the High Fidelity world. Actually, 3 types are readily available covering virtually all requirements. They are the 2A3, the 300B and the 845.

Understand that they were created long time ago for the first talking movies, we must respect them in order to arrive at the musical perfection they are able to provide. Those triodes were tyrannical with the tecnicians who are faced in desinging an amplifier. The design around the tube must be perfect or some default will emerge and deteriorate the listening result, mainly by hum, and / or a defeniciency of the bass and trible. If the cost needs to be lowered it is easier to use the symmentrical mounting (Puss Pull) which does not require the same care.

Each model of the TRIODE SPIRIT line has a regulated power supply which provides a constant voltage in all circumstances on all the amplifier stages. The regulated power suppply, expensive to realize for the 300B models needs the use of 3 tubes to work properly.

Response in low frequencies
The size and the weight of the transformer is decisive because it conditions the value of the primary inductance which must be as high as possible. The output transformer as a vital part must according be designed at its best, taking into account the finest technology, while respecting the rules of art.

The treble response
The dynamic input capacitance (about 50 to 100pF) of the power triode requires a preamplifier stage with low output impedance - practically a power stage - able to provide current in high frequencies, in a sort forcing the output triode to accept the modulation against its will. To obtain this, we designed a completely innovative input stage; it consists of 2 tubes put in a configuration of ultra linear µ follower pentode. This stage presents the double benefit to have very low output impedance (about 100 Ohms) and a negligible distorsion.

This feature is valuable because it passes on an ultimate profit: it does not change the original sound of the output triode by an innoportune compensation effect. This feature does not alter the special sound of each triode and allows making auditory comparisons really significant between tubes of different origin. For this last reason, we named this line of amplifiers ”Triode Spirit” hopping to show the devoted care, the quasi religious character of our reverence for the great triodes of the past.