MartinLogan The Quest Speaker System user manual Passive Bi-amplification

Operation

Passive
Bi-amplification
For those of you that desire ultimate
performance, the Quest may be
passively bi-amplified using the	OUTPUT	INPUT
existing internal passive crossover	Preamplifier
elements.

WARNING! Only after the BI-	OUTPUT	Amplifier	OUTPUT
WIRE/BI-AMP SWITCH is in the	INPUT		INPUT
Bi-Wire/Bi-Amp position may
you connect individual runs of
speaker cable from your ampli-		Amplifier
fier to the Low-pass and High-	OUTPUT		OUTPUT
pass AMPLIFIER CONNEC-	INPUT		INPUT
TIONS binding posts. Damage
will occur to your amplifiers if
the BI-WIRE/BI-AMP SWITCH is
not in the correct position!

Passive bi-amplification takes the bi-	Figure 3. Horizontal passive bi-amplification. One channel shown. BI-WIRE/BI-AMP
wiring concept one step further. Now
		SWITCH in Bi-Wire/Bi-Amp position.
you will have a dedicated channel of
amplification directly connected to the		Horizontal Bi-amping (read Warning above).
high and low-pass sections of the Quest crossover.
There are two different methods to passively bi-amplify. The		With horizontal bi-amping, one amplifier drives the high-
		pass section while the second amplifier drives the low-pass
first, and most common, is referred to as Horizontal Bi-		section. To horizontally bi-amplifyyour Quests, connect
amping. The second method that is gaining in popularity is		the low frequency amplifier to the Low-Pass Input + and -
referred to as Vertical Bi-amping. With either method		AMPLIFIER CONNECTIONS binding post. Connect the high
you may use two stereo amplifiers or four mono amplifiers,		frequency amplifier to the Full-Range/High-Pass Input
or two mono amplifiers and one stereo amplifier. Get the		+ and - binding posts. Next, connect the left and right
idea? With either form of passive bi-amplification, your pre-		preamplifier outputs to the appropriate left and right inputs
amplifier must have dual outputs. If your pre-amplifier is not		of both amplifiers. See figure 3.
so equipped, you must either purchase or construct a "Y"		Vertical bi-amping (read Warning above).
adaptor.
Horizontal bi-ampingallows you to use two different		With vertical bi-amping, each of the stereo amplifiers is
		dedicated to one speaker. To vertically bi-ampyour
types, models or brands of amplifiers (i.e. tubes on top,		Quests, connect the left amplifier channel of amplifier #1 to
transistor on the bottom), assuming that they have identical		the Low-Pass Input + and - binding post and the right
gain or that one stereo pair has adjustable gain. However,		amplifier channel of amplifier #1 to the Full-Range/High-
we recommend that you use two identical amplifiers (i.e.		Pass Input + and - binding post. Repeat the same
same brand and model). If the amplifiers of choice do not		procedure for the other speaker with amplifier #2. Connect
have the same gain characteristics, then a sonic imbalance		the left preamplifier outputs to both inputs of the left channel
will occur between the high-pass and low-pass sections of		amplifier (#1) and the right pre-amplifier outputs to both
the speaker, and integration between the two will suffer		inputs of the right channel amplifier (#2). See figure 4 on the
greatly. The very nature of vertical bi-ampingdictates		following page.
that both amplifiers be identical.

Page 12 Quest User's Manual