A while back there was a discussion on this forum about an easy way to bidge a dual channel amplifier. No need for special phase splitter/turner boards. No need for changes to the internal wiring of the amp to be bridged. If you are like me, you likely have several amps laying around that you would like to bridge - just to hear how it sounds. If so, here is some good news: all you need is a pre-amp with a balanced output. Then create a quick interconnect that takes the in-phase signal (+) and the out of phase signal (-) and feed that into the Right and Left input RCA's. We are assuming that the preamp here has a volume control and that we have 2 identical amps that we can bridge for each channel.
As it turned out, I have a DAC with balanced output and 2 HAFLER 200's that would work for this experiment. All I needed was to create the interconnect:
That's it. Here Pin 1 is common ground. Pin 2 is (+) and Pin 3 is (-). (+) to one channel and (-) to the other. The speaker is connected bridged between the two positive output terminals of the power amp. Essentially the amp is running with each channel amplifying each leg of the balanced signal.
So how does it sound? - Well that is the most surprising: the old HAFLER 200's sound more alive than ever! Trumpets and saxophones have more bite. And I hear details on old familiar tracks that only the best amps manage to bring out. The Haflers already have good specs even by today's standards. Re-capping helps as well. But this inexpensive bridge interconnect brings them to a new level. I cannot explain it. Why? Common mode rejection of some left-over distortion?
If you have any idea why this is happening, please post your thoughts. Or if you just want a fun and easy project for the holidays, this might be what you have been looking for.
Have fun.
As it turned out, I have a DAC with balanced output and 2 HAFLER 200's that would work for this experiment. All I needed was to create the interconnect:
That's it. Here Pin 1 is common ground. Pin 2 is (+) and Pin 3 is (-). (+) to one channel and (-) to the other. The speaker is connected bridged between the two positive output terminals of the power amp. Essentially the amp is running with each channel amplifying each leg of the balanced signal.
So how does it sound? - Well that is the most surprising: the old HAFLER 200's sound more alive than ever! Trumpets and saxophones have more bite. And I hear details on old familiar tracks that only the best amps manage to bring out. The Haflers already have good specs even by today's standards. Re-capping helps as well. But this inexpensive bridge interconnect brings them to a new level. I cannot explain it. Why? Common mode rejection of some left-over distortion?
If you have any idea why this is happening, please post your thoughts. Or if you just want a fun and easy project for the holidays, this might be what you have been looking for.
Have fun.
Remember that with this configuration if you are using an 8 ohms speaker each amplifier will '' see '' the load as an 4 ohms speaker
Consider the gain of your preamp has to match your amp and your source to your expected listening level
Yes. The pre-amp is where the magic is here. The good news is that the signal the speaker sees is 6dB higher than with a single amp.
Any harm in making that the same? - I mean: I have not seen any preamps personally where pin one is not also signal ground. But if not, two 10K resistors between pin 2 and pin 3 should work to create a floating signal ground.
@Speedskater: which preamps have you seen where pin 1 is not common ground?
@Speedskater: which preamps have you seen where pin 1 is not common ground?
Pin 1 may or may not have continuity to pin 3 XLR low, but it can be a winding route.
But the problems will be:
1] Pin 1 is not audio circuit common, it is the metal chassis/shield.
1] Floating transformer outputs.
2] Passive/Impedance outputs.
But the problems will be:
1] Pin 1 is not audio circuit common, it is the metal chassis/shield.
1] Floating transformer outputs.
2] Passive/Impedance outputs.