Grimm Audio MP1, Руководство пользователя

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are 2 mm sockets so multimeter test pins fit directly. Please check these voltages
before connecting the microphone. Mark that the heater voltage will measure ap-
proximately 0.1 V higher at this socket than indicated above. This is on purpose to
compensate for cable voltage loss.
To minimize the risk of accidental damage to microphones equiped with 3.9 V
tubes by plugging these into a 6 V MP1 supply, Grimm Audio has decided to deliver
its 3.9 V version with an XLR6 socket and the 6 V version with an XLR7 socket. The
factory set voltage is indicated on the back. Of course, if a user chooses to change
the internal voltage settings, the XLR pin count no longer gives the right indication!
This is one of the reasons we disencourage the change of factory settings.
The MP1 features a rotary switch to allow a choice of polar pattern on microphones
equipped with such a remote control input. The corresponding pin on the XLR6 or
XLR7 microphone connector can be varied between 0 V and the 120 or 145 HT volt-
ages or between 0 V and HT + 40 V, depending on the internal jumper setting. For
example: if HT is set to 120 V, it can be varied between 0 and 120 V or 0 and 160
V. (The 40 V over-voltage is not available at the 210 V setting as there are no micro-
phones that require that).
Changing the internal settings
Opening up the MP1 and changing its internal presets or trimmings is best left to a
trained technician. When switched on, there are potentially dangerous voltages as
high as 300 V inside. Grimm Audio cannot accept any responsability for damages
to either persons, or the MP1 itself, or to any microphone connected by unwittingly
chosen voltages or polarities.
Before opening the MP1, switch off the mains power and remove the power cord.
Also remove any audio cables. Wait 30 seconds to allow the HT on the electrolyt-
ics to reach a safe value (< 40 V). Remove the 2 screws from one side of the cover
as well as the 2 screw opposite of them on the other side. Carefully slide the cover
backwards, away from the wooden front. The electronics will then become visible.
An overview of setting and trimpots of the pcb is given in fig.1 on the next page.
High Tension (HT) settings
Jumpers 7 to 10 set the HT (high voltage to the microphone) to 120, 145 or 210 V.
The junper on the left-hand row sets the voltage, the jumper on the right-hand row
sets the crowbar protection. They should always be changed in pairs: both in the
120 V position, or both in the 145 V position, or both in the 210 V position. Failure
to do so may shut the MP1 down, or incriminate correct protection against over-
voltage.