Balanced/Unbalanced switch action on MC302 amplifier (or similar)

[eziggy]

Originally Posted by LazyBorzoi

Just curious what you mean by "disappointed"?
Were you expecting a noticeable difference from switching from unbalanced to balanced?

I just had the switch unknowingly on unbalance when I needed it to be on balanced. I was using balanced interconnects. Sounded anemic and had lack of mid-bass and bass before the fix, thought the cables weren’t good. Just user error, cables sounded great after.

[LazyBorzoi]

Originally Posted by eziggy

Sounded anemic and had lack of mid-bass and bass before the fix, thought the cables weren’t good. Just user error, cables sounded great after.

That is very strange...
Balanced cables are designed to reduce the common noise in the wires between your components, nothing more. They do so by cloning the "+" signal, inverting it and sending this copy in the "-" wire, and later they subtract one from the other. As a result, the common noise (which should be the same in each wire) is rejected.
If you hear sonic changes by flipping the switch from unbalanced to balanced using the same (balanced) interconnects, you should be really concerned...

[eziggy]

Originally Posted by LazyBorzoi

That is very strange...
Balanced cables are designed to reduce the common noise in the wires between your components, nothing more. They do so by cloning the "+" signal, inverting it and sending this copy in the "-" wire, and later they subtract one from the other. As a result, the common noise (which should be the same in each wire) is rejected.
If you hear sonic changes by flipping the switch from unbalanced to balanced using the same (balanced) interconnects, you should be really concerned...

Have you tried this on a quad balanced McIntosh amp? Just checked with Chuck at McIntosh to make sure something seriously wasn't wrong with the amp or more realistically me.

I asked if the signal is halved when the switch set to "unbalanced" using balanced interconnects. He mentioned that essentially using the XLR connection with the switch to UNBAL gives half voltage, which reduces output by 3dB.

"When the + &- xlr wires are received by an unbalanced amp, the - is re-inverted and added, then the signal is cut in half, so 2 legs at 2.5v still ends up at 2.5v total.

When entering a fully balanced amp like the MC452, the + drives a 225 watt fully balanced amp section and the - drives a 225 watt fully balanced amp section, then the - is inverted and combined magnetically with the + in the output Auto former, for 450 watts, as the 2nd amp was inverted, any noise or distortion that is identical in those 2 sections is then out of phase and cancels, so the amp cancels it's own self noise. This is only possible in the McIntosh quad balanced amp."

I always appreciate the amazing support from Chuck and McIntosh!

[LazyBorzoi]

Originally Posted by eziggy

Have you tried this on a quad balanced McIntosh amp? Just checked with Chuck at McIntosh to make sure something seriously wasn't wrong with the amp or more realistically me.

I asked if the signal is halved when the switch set to "unbalanced" using balanced interconnects. He mentioned that essentially using the XLR connection with the switch to UNBAL gives half voltage, which reduces output by 3dB.

"When the + &- xlr wires are received by an unbalanced amp, the - is re-inverted and added, then the signal is cut in half, so 2 legs at 2.5v still ends up at 2.5v total.

When entering a fully balanced amp like the MC452, the + drives a 225 watt fully balanced amp section and the - drives a 225 watt fully balanced amp section, then the - is inverted and combined magnetically with the + in the output Auto former, for 450 watts, as the 2nd amp was inverted, any noise or distortion that is identical in those 2 sections is then out of phase and cancels, so the amp cancels it's own self noise. This is only possible in the McIntosh quad balanced amp."

I always appreciate the amazing support from Chuck and McIntosh!

Interesting. No, I don't believe my amp (MC302) is quad-balanced...
So on my amp if I use balanced cables, the volume doesn't change regardless of the switch position but if I use unbalanced cables then flipping the switch changes the volume. The reason for this was explained by our fellow forum member in post #7.

[eziggy]

Originally Posted by LazyBorzoi

Interesting. No, I don't believe my amp (MC302) is quad-balanced...
So on my amp if I use balanced cables, the volume doesn't change regardless of the switch position but if I use unbalanced cables then flipping the switch changes the volume. The reason for this was explained by our fellow forum member in post #7.

Sounds like it's the quad balanced design. Without it, it would work as other amps I imagine.

[LazyBorzoi]

Originally Posted by eziggy

Sounds like it's the quad balanced design. Without it, it would work as other amps I imagine.

In this case, can you confirm one more time that when you are "using the XLR connection with the switch to UNBAL gives half voltage, which reduces output by 3dB." on your amp?
Because for my amp (302) the output volume doesn't change when I use XLR cables regardless of what state the switch is in...

[eziggy]

Originally Posted by LazyBorzoi

In this case, can you confirm one more time that when you are "using the XLR connection with the switch to UNBAL gives half voltage, which reduces output by 3dB." on your amp?
Because for my amp (302) the output volume doesn't change when I use XLR cables regardless of what state the switch is in...

Sure, will do, I will try again tonight. I am 99% sure it is the case since I fell into this as I was trying to lock down why the new speaker cables had recessed bass/mid-bass and didn't sounded great using my Fire XLRs. One thing to note, for me it was more about less volume in some frequencies and not total volume.

I was trying different interconnects, AQ Earth RCAs vs. Fire XLRs. When I put the Earths in I noticed it was set to UNBAL, and when reverting back to Fires and flipping the switch to BAL the sound became fuller, particularly noticeable in bass.

Felt like an idiot since I spent a couple of sleepless nights on this, haha!

[LazyBorzoi]

Originally Posted by eziggy

Sure, will do, I will try again tonight. I am 99% sure it is the case since I fell into this as I was trying to lock down why the new speaker cables had recessed bass/mid-bass and didn't sounded great using my Fire XLRs. One thing to note, for me it was more about less volume in some frequencies and not total volume.

I was trying different interconnects, AQ Earth RCAs vs. Fire XLRs. When I put the Earths in I noticed it was set to UNBAL, and when reverting back to Fires and flipping the switch to BAL the sound became fuller, particularly noticeable in bass.

Felt like an idiot since I spent a couple of sleepless nights on this, haha!

I wonder if those differences that you hear are due to difference in volume between the two switch positions...
Our hearing sensitivity is a very complicated function of frequency and volume (see Fletcher–Munson curves) and at low volumes, we are more sensitive to the mid-range frequencies which makes it difficult to detect bass BUT as you increase the volume up, bass and treble start coming out and become more pronounced...

[eziggy]

Originally Posted by LazyBorzoi

I wonder if those differences that you hear are due to difference in volume between the two switch positions...
Our hearing sensitivity is a very complicated function of frequency and volume (see Fletcher–Munson curves) and at low volumes, we are more sensitive to the mid-range frequencies which makes it difficult to detect bass BUT as you increase the volume up, bass and treble start coming out and become more pronounced...

Sorry for the delay in getting back on this, was able to finally sit down and try this out. There is a very slight difference in overall volume, can be heard in the bass a bit as well. It’s slight, you really need to be listening for it. Going off what McIntosh, it should be a few DB.