Manley Labs MM/MC GRAMOPHONE CARTRIDGE PREAMPLIFIER owner manual Page

Let the preamp tube(s) cool down, if necessary, before handling. Tube heater filaments are somewhat more suceptable to damage when warm or hot.

Each tube should require only moderate force for removal and replacement. Gently rock the tube back and forth a bit during removal or replacement. Avoid bending the circuit board. Notice that the heaters of the 6922s are connected in series, and neither channel will function if one of the filaments is open or burned out, or unless both of the 6922s are installed. Akin to those old Xmas tree lights in the attic, no? Be careful to straighten any bent tube pins prior to installation; pin misalignment will make fitting the replacement tube difficult or impossible, and may damage the socket. Be careful to put replacement tubes in the proper sockets.

Never substitute other type numbers of 9-pin tubes without careful research. There are literally thousands of types that share the 9-pin mechanical basing arrangement, but NOT the internal electrical connections! Mechanically compatible tube plugs and sockets by no means indicate electrical compatibility! And random experimenting can easily and quickly destroy the substitute tube and other parts of the preamp!

Three tube types that are electrically and plug-socket compatible with the 6922 dual triode are the 7308, 6DJ8 and the ECC88 / E88CC. There is no direct replacement for the 7044 dual triode.

VARI	RIGHT		MC-1 IN		MC-1 IN	LEFT		VARI
					CHASSIS
					GROUND
					CIRCUIT
	LINE IN		MC-2 IN		MC-2 IN		LINE IN
	RFI	SHUNT	MM IN	SERIAL #	MM IN
					RFI		SHUNT
	ON	OFF			OFF		ON
	1						1
	2						2
FIXED								FIXED

Please direct any questions to your dealer or MANLEY LABS for further assistance.

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