output dynamics management

[johnsonabq]

Looking at the block diagram for my MB Subway D-800+ I see something called "Output Dynamics Management". Can someone explain exactly what this is? Is it some sort of compression? Thoughts? thx

 

[/\/\3phist0]

Paging @agedhorse

 

[two fingers]

Paging @agedhorse

Yup. @johnsonabq one of Mesa's design engineers is our own @agedhorse ..... kind of a handy guy to have around in more ways than you can imagine. He can't camp out here all day. But he swings by often. He should be able to clear this up for you.

 

[two fingers]

It looks like a simple switch going to ground. Possibly a bleed resistor that changes the impedance? That's just my own spitballing. Pure speculation on my part.

 

[agedhorse]

There is circuitry that senses as the power amp is getting close to rated power. As the power amp gets close to the beginning of saturation, this circuit block emulates the various ways the signal might behave if the class D amp was in fact a tube power amp. This includes gain droop, distortion harmonics, symmetry and recovery without the pumping and spongy feel normally associated with traditional VCA's, LDR's or FET gain cells. The 2 ohm switch simply re-scales the circuit.

 

[BassmanPaul]

You heard it right from the Horse’s mouth! He did design the amp after all.

 

[johnsonabq]

There is circuitry that senses as the power amp is getting close to rated power. As the power amp gets close to the beginning of saturation, this circuit block emulates the various ways the signal might behave if the class D amp was in fact a tube power amp. This includes gain droop, distortion harmonics, symmetry and recovery without the pumping and spongy feel normally associated with traditional VCA's, LDR's or FET gain cells. The 2 ohm switch simply re-scales the circuit.

Thanks for the quick reply. It sounds like the Advanced Power Management that TC Electronics uses. Or is that a different beast?

PS... I find that 2 ohm switch to be very handy.

 

[agedhorse]

Thanks for the quick reply. It sounds like the Advanced Power Management that TC Electronics uses. Or is that a different beast?

PS... I find that 2 ohm switch to be very handy.

TC's take is quite different, and their's is done in DSP.

The Subway's management is all analog, and transparent until reaching rated power.

There are many different ways to skin this cat, different solutions for different players.

 

[johnsonabq]

TC's take is quite different, and their's is done in DSP.

The Subway's management is all analog, and transparent until reaching rated power.

There are many different ways to skin this cat, different solutions for different players.

Thank you sir.