Frequency Dependant Damping?

[electro samurai]

marshall amps, claim that they add a circuit to some of the amps, called Frequency Dependen Damping.
they claim this:

"FDD (Frequency Dependent Damping) is a radical new feature that is exclusive to Marshall Amplification and accurately mimics the way an all-valve amplifier interacts with a loudspeaker. As a result of FDD, your amp will give you a sound and feel never before thought possible in such an affordable, non-valve amp."

is this possible?
is it true?
is it simple?
can i build it?

 

[dimitri]

>can i build it?
yes you can. This is a simple combination by voltage and current feedback (see components in red boxes).

 

[Nelson Pass]

"FDD (Frequency Dependent Damping) is a radical new feature that is exclusive to Marshall Amplification and accurately mimics the way an all-valve amplifier interacts with a loudspeaker. As a result of FDD, your amp will give you a sound and feel never before thought possible in such an affordable, non-valve amp."

They are always trying to emulate tube sound, but I don't think
they ever do.

 

[jan.didden]

I challenge that FDD is exclusively to Marshall amps. EVERY amp ever made has FDD. In every amp, damping decreases as frequency increases.
They probably thought, hey, if we can't beat it, let's make it a FEATURE!

Reminds me of that ad, where the sales manager tells his sales man, " What? They offer 360degrees dispersion? Well, we'll give them 400 degrees!"

Jan Didden

 

[SY]

Well, more than that, that resistor in series with the speaker return increases the output Z, which certainly causes "variable damping" in any speaker load that has a non-constant Z vs. frequency (i.e., 99% of all the speakers on Earth).

BTW, Jan, that new avatar looks like Diana Krall. I preferred the last one.

 

[TheMickster]

Use the VST plugin?

Now that SofTubes have made a plugin of the Marshall Plexi, they could build that into a solid state amp to give it a valve sound.

 

[WLaturno]

regarding FDD circuit ...issue

Old thread, modern day issue with a 100HDFX - when I push the button in, something of a short circuit happens ( the 100 watt light bulb in series with the power in starts to glow bright - and the fan speed starts to drop noticeably ) . . . from the schematic, this is not making much sense....I was thinking C12 was shorted to ground . . .what does not make sense to me is that the FDD switch is a DPDT, but the schematic only shows SPDT.. I might be being too vauge, but I can tell there is an issue going on and I would like to fix it....appreciate any help...