V(-1). Was it made before or after V0? It uses just an 7025 electron tube. A Sowter input transformer direct to grid (no capacitor) and a Stancor military output transformer directly to anode. A cathode resistor of 470ohms reduces the positive potential from the cathode electron cloud. One 9 volt supplies the heaters with 5V through a 7005 regulator. Another 9V battery supplies the anode with 9 volts. Everything with drawer battery holders on one box. By having the anode battery in all the time and snapping in the other battery soft start and stop in ensured. Fuses should have been added. It sounds as if you are about to take off. Great for soft voice singing.
V0. It started existence on around 2000 as a 6V ECC86 DI preamplifier. In a very small aluminum diecast and then grey primer painted box. It did not sing so sometime during the last years after the Pleiades discovery of using a resistor from anode to grid to free the electrons it has been converted to an ECC82 12V powered low noise pre pre amp DI. Most of the other components are still there. A 10MΩ resistor from an earlier version connected to ground is now connected to anode and the other side left to grid. The cathode of the 1/2 ECC82 used is connected to ground. The small military transformer on top of the box is connected directly to anode. So it is a single ended class A pre amplifier. Class A means electrons are flowing all the time. The input 1/4in mono female is coupled to grid through a 10nF capacitor. This is all. Very similar to Pleiades V6. The output transformer winding inductances are 29H to 1.1H. It is an Admiral TF1RX11YY SC-B-91267, 20,000Ω to 600Ω. The 600Ω winding is connected to a Neutrik chassis male output. The V0 has been fed by a Beyer M55 and external input trasformer. It's output was connected to EMI RS61. It sings. There may be photos of it on another euroelectron post.
V1. It is using an electrometer tube (CV2269) and operates with just a 1.2V battery. The idea of using an electrometer tube came after a conversation with Sean Davies on his use of electrometer tubes for condencer microphones. It was first observed by accident that returning the grid circuit to the positive terminal of the heater battery made a vast difference in anode current. Then an accidental short circuit of the plate circuit proved that the tube could operate with no Vb. Effectively it was the heater battery supplying both heater, grid and plate circuits. Not very low noise. And microphonic too.
V2 version with an 12AU7 or ECC82. 12V powered. Initially 10MΩ was used form grid to cathode. The cathode was connected to ground. After the V4 experiments a less high Megohm resistor is now connected from anode to grid.
V3 experimental gig with breadboard? Or a small box with a circuit like V4 and external battery supply? Or a little cast aluminum box being much before V1 with ECC86. Never worked quite well. It is now with EF183 and uses the already installed military output transformer. A short of DI high Z in low Z output. The output transformer successful operation led to V6.
V4 EF183 single stage with no input or output transformer. It is a 10KΩ anode follower with a 3.9MΩ anode to grid resistor to free electrons and provide a normal transconductance. Initially a 4.8V supply of 4 AAA batteries was used for both heaters and anode. As of now it is just 3 of them giving approx. 3.7 volts and although gain is less the noise performance sounds still better. The EF183 is triode connected.
V5 A 2 stage EF183 pre preamplifier. Only input transformer using a Magnetec Nanoperm core. Same principles as on V4. Using two li ion 3.7 batteries in series and a fuse for the series connected heaters and anode supply. The 7.4V feed the anode circuits. Very low noise and juicy sound too as the second electron tube is now pushed by the first stage. Originally designed for microphones such as the Electro-Voice RE16. It sounds great on electric bass too when it is connected to the 5H secondary of the input trasformer. The 5 Henries inductance in parallel with the pickup creates a Pleiades filter compensating for excessive bass to brain perception and making the electric bass full of clean bass midrange and treble detail.
V6 similar to the Pleiades V4 but with no 10KΩ anode resistor. It has an input and output transformer. When the heater voltage is reduced to the sweet point the singing sound becomes so alive it is frightening.
V7 not yet specified. It may be two electron tubes and an interstage transformer playing the role of 2 magnetic heads with their airgaps touching. Intended for analog simulation of analog high speed tape recording. The rising frequency "recording" characteristic and the low pass "reproduction" characteristic creating instateneous peak limiting with rounded waveform. The interstate transformer is driven to soft saturation. Constant current operation of the primary of the interstate transformer is automati sly arranged by the high Z out of the tube driving a low inductance inductor. A Pleiades filter as in tube tape recorders where a high Z out drives the magnetic head.
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