Mesa/Boogie Vacuum Tube Audio 3 - 8 GROUND SWITCH, 3 - 9 CONGRATULATIONS, Volume Control

3 - 8 GROUND SWITCH:

At the very right of the Tube Bay is a mini-toggle switch which you will probably set once and then leave alone. The easiest way to understand the purpose of this switch is to consider the TIGRIS as having two separate reference groups to ground: one external and two internal. The internal Grounds are the common zero voltage points for the power supply and audio circuitry. The external Ground is the safety

connection of the metal chassis to your home’s Ground Circuit.

EL84 6V6

The grounding switch either connects (coupled position) the internal grounds with the external, or floats (isolated position) them. In either case, the chassis remains connected to your home’s Ground Circuit for safety reasons.

2/3 PENTODE

2/3 TRIODE	COUPLED	ISOLATE
POWER SELECT	AUDIO GROUND

Ideally, only one component in your system should be internally referenced to A.C. ground. Customarily, this is the source component. If more than one component of the system is tied to power ground in this fashion, audible hum and buzz may occur. To find out what position ( grounds isolated / grounds coupled ) is appropriate for your system, engage the WARM switches to their OPERATE position. Open Volume control of the TIGRIS to about its 9 o’clock position while you have one ear pressed close to the drive units of one of your speakers. If the length of your speaker cable does not permit control over the volume and ground switch while close to the speaker, you might ask a friend to help you.

You do NOT feed signal, but merely listen for the level of noise.

Slowly increase gain until you hear noise reproduced by your speakers. Now change the switch setting. If the noise level drops or becomes inaudible, you have found the optimum setting. If it increases, keep the switch in the original setting and experiment with cheater plugs on some of the other components, one at a time. NEVER saw off the ground leg of a three prong connector to reduce noise - use an adaptor!

If you don’t notice any noise in either the coupled or isolated position, you may, with critical listening, still discern a difference in overall sound quality. The isolated position will probably provide a more open and spacious soundstage.

3 - 9 CONGRATULATIONS:

You are now ready to commence your first listening session. Cross off the following check list in your mind: • The Headphone / Speaker selector on the Rear Bay is set to SPEAKERS.

•The Input Selector shows the source you intend to play

•The Volume control is fully turned down.

Now select PLAY on your source component and slowly open the Volume control until a pleasing play back level is achieved. As a reminder...always raise the level of the volume that you are going to listen to gradually. Its a lot easier on your speakers an d your ears. It might be a good idea to get into the habit of reducing the TIGRIS’ volume when your listening session is over and you shut down

WARM	CD	AUX 1		WARM
	TAPE		AUX 2	V A C U U M T U B E A U D I O
OPERATE				OPERATE
				HEADPHONE
	Input Selector			Volume Control

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