Thursday, March 3, 2011

Townshend Glastonbury Preamp


The Glastonbury Autotransformer Passive Stereo Preamplifier is a High Fidelity line level control centre that accepts 6 inputs, adjusts gain and supplies two outputs.
The heart of the machine is the 27 tap Deep Cryogenic Treated (DCT) wire wound autotransformer with 80% Nickel mumetal laminations for ultimate performance.
The 6 position input selection is by manual control by the left hand rotary selector knob.
The gain control knob is primarily remote controlled but may be manual.
There are 6 stereo RCA phono inputs, two of which have parallel XLR connectors and two phono stereo outputs with parallel XLRs.
The XLR connectors are unbalanced in the Pre 1 version and fully balanced in the Pre 2 version. (8 additional 1:1 EDCT wound transformers).
The remote controlled volume control is by a 23 position switch in 2dB increments which gives attenuation from 0dB to -42dB and finally off.
For fine gain adjustment, there is a remote controlled +1dB function.
For extra gain, there is a further remote controlled + 10dB function which shifts thegain overall by an additional 10dB.
The combined gain possibility has a range of 53dB in 1dB increments from -42dB to +11dB.
There is a remote controlled Mute function.
There is a remote controlled Mono function for optimum mono LP listening.
There is also a DC/AC coupled allows for AC coupling to ensure that there is no possibility of performance degradation due to DC in excess of 5mV on any of the selected inputs.If there is no DC on the selected input, the very high quality DC blocking capacitors may be bypassed, by the rear control switch, for the ultimate in fidelity.
The only power requirement is for the control circuitry. This is provided by a 15V, 1A DC mains powered universal “wall-wart” AC to DC converter. There is no connection between the control circuitry and the signal circuitry.
The unit will function without power on purely manual control, but there is no +1dB, +10dB, mute or DC possibility.
All internal signal wiring is by DCT treated wire.
When configured unbalanced and DC coupled with the volume control set at 0dB, the signal passes unaffected straight through the unit from input to output.
As this is a purely passive device, there is no mains-born noise degradation. This, when combined with the EDCT wiring, results in the most accurate, uncoloured and open preamp possible.
The case comprises a 12mm thick anodized aluminium front panel with 6mm anodized aluminium side and top panels.


Frequency response 8Hz-100kHz +/1 0.1dB
Maximum signal level 4VRMS 8Hz 10VRMS 20Hz
Maximum DC offset 5mV. (for undistorted 8Hz  when set to DC)
Distortion less than 0.01% 400Hz 10V 2nd and 3rd only
The input impedance is dependent upon the load impedance and the gain setting. So, with a power amplifier having 20k input impedance (typ).
At 0dB, the input impedance is 20k.
At -10dB (normal listening) the input impedance is 200k
At + 11dB gain, the input impedance is 1.6k.
6 Gold plated stereo RCA phono sockets
2 Gold plated XLR sockets unbalanced
2 Gold Plated stereo RCA phono sockets
2 Gold plated XLR sockets unbalanced,
Power 15VDC 1A. (Remote control only)
Width                    490mm (19.3”)
Height                   120mm (4.7”)
Depth                     380mm (15”)
Weight                   11kg    (lb)

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