MA-2275 Power question

bingperry

Member
I have a MA-2275 Int amp and I was reading the manual and see that you can use the amp section and add another amp. I would like to know if I could bridge the power from the MA-2275 and use a MC-275 bridge it and have 150 watts per side. thanks
 
The MA2275 has a second preamp out which allows the use of another stereo amp. The 75/75 watt amp in the MA2275 can not be bridged to mono. We do not recommend passive bi-amping speakers with tube amps unless an electronic crossover is used in front of the amps.
The second Prue amp outs are often used with powered subs when small main speakers are used and you want to fill in the bottom octaves.

Ron-C
 
ron-c said:
We do not recommend passive bi-amping speakers with tube amps unless an electronic crossover is used in front of the amps.
I've seen this mentioned before elsewhere. What's the rationale for this Ron?
 
Tubes are high impedance devices, usually thousands of ohms. Speakers are 2,4,8, ohm etc. The match is made through the output transformer and the ratio is so large that the tubes will not see the passive speaker crossover and try to deliver power even though the driver is not connected when passive bi-amping. This will cause the amp to run hot and be unhappy.
On a McIntosh this 'turns ratio' is 1/4 of other tube amps due to the Unity Coupled output design but still not a great idea.

Ron-C
 
I also own a MA2275.
I am thinking of bi-amping like this:
-use ma2275 to drive the tweeter.
-the second pre-out of ma2275 is input into two mc275 and each mc275(bridged for mono) drives the bass of each side of the bass.
Is that possible?

Leung
 
The MA2275 has two pre amp out puts on the rear panel. The one for the internal amp is connected with RCA 'U' jumpers and the other is in parallel. To use tube amps in a bi-amp setup a electronic crossover needs to be used between the pre amp outs of the MA2275 and the two two amps. The crossover frequency needs to approximate that of the speakers' internal crossover. The electronic crossover could be set slightly above (low) or below (high) the speaker's normal crossover point to avoid excessive phase shift created when crossovers are stacked. 12 Db per octave slopes would be fine since the idea is to keep the tube amps from playing outside of a load.
Pro sound type electronic crossovers will be fine as made by Rane and others.

Ron-C
 
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