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How to set the Speaker Load switch when the Model 275 v.2 is
configured for Bridged Mono operation:
Single 8 Ohm Speaker
In this case the Speaker Load switch should be set to 4-8
Ω.
Single 4 or 6 Ohm Speaker
In this case the Speaker Load switch must be set to 2-3
Ω.
Two 8 Ohm Speakers
In this case the Speaker Load switch must be set to 2-3
Ω. Connect the + wire of the
first speaker to the Speaker Output A red R channel positive terminal and connect
the speaker’s – wire to the red L channel positive terminal. Connect the second
speaker similarly to the Speaker Output B red R and L positive terminals.
Note:
Never connect two 4 ohm speakers for bridged mono operation. This results in a 1
ohm load on each channel which could cause the amp to overheat and shut down.
Bi-Amping Using Two Model 275 v.2 Amplifiers
If your speakers have separate input terminals for their Low and High frequencies there is usually a
greater sonic advantage using two Model 275 v.2 amplifiers
to ‖bi-amp‖ your speakers rather than
bridge them as monoblocks. When bi-amping the Bridged Mono switch must be set to its Normal
(Stereo) position.
When set up for bi-amping you will use one channel of one 275 v.2 to power the high frequency drivers
and the second channel of the same amp to power the low frequency drivers. Since both channels of
the amp need the same audio signal you will need to connect the Loop Out jack of one channel to the
input of the second.
If you connected your preamp to the 275 v.2’s L channel Input jack to then you’ll
need a short RCA
cable to connect the 275 v.2’s L channel Loop Out jack to its R channel Input jack.
A + B Speaker Load Switch
The Speaker Load switch gives the Model 275 the flexibility to drive very low impedance loads. Such
situations can occur when the Model 275 is asked to drive multiple pairs of speakers.
For a single pair of 4 ohm or 8 ohm speakers the Speaker Load switch may be set to its 4-
8Ω position.
The Speaker Load switch must be set to 2-
3Ω whenever the load will be lower than 4 ohms. Speaker
loads below a 4 ohm impedance can cause the Model 275 v.2 to rapidly overheat and cause audible
distortion.
These are examples that require the 2-3
Ω setting:
1. Driving two pairs of speakers whose impedances are unknown.
2. Driving two pairs of speakers whose impedances are each lower than 8 ohms. For example,
two pairs of 4 ohm speakers driven simultaneously = 2 ohm load.
3. Driving three pairs of 8 ohms speakers simultaneously = 2 .66 ohm load.
4. Driving a single 4 ohm speaker in Bridged Mono operation = 2 ohm load
5. Driving two 8 ohm speakers in Bridged Mono operation = 2 ohm load
Note:
For the coolest possible operating temperature we recommend setting the Speaker Load
switch to 2-3 ohms even if you are using a single pair of 8 ohm speakers.
