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Mat Nieuwenhoven Mat Nieuwenhoven is offline
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Default Introducing a New Horse to the Stable

On 12 Sep 2019 20:28:33 GMT, Trevor Wilson wrote:

snip

**Let me be very clear about several things:

* NFB is fine. In fact, NO audio amplifier can work without it.
* GLOBAL NFB is also fine. When properly applied.
* I have a personal preference for the amplifiers I use, which employ
lots of local NFB and no global NFB. Others may have a different opinion.
* As part of my education into the world of zero global NFB amplifiers,
I subjected myself to a couple of single (unfortunately) blind tests,
between two, otherwise identical, amplifiers. One employed zero GNFB and
one employed a modest amount of GNFB. I preferred the zero GNFB one.
Since that time, I subjected several (10) of my clients to the same test
(DBT). The zero GNFB models was preferred every time. Except one.
* Once mo I would posit that part of the reason why some listeners
prefer valve amplifiers, is due to the fact that global NFB levels are
very low, or non-existent.


But, again, in the real world, negative feedback, done properly, has
many more advantages than disadvantages.

**Again: No issue with NFB. In fact, no issue with GNFB, when done well.


How do modern switching amps (class D) stack up for HiFi use? Aren't
most PA systems now fully digital? Do they actually use FB? If I look
at the spec sheet of the TDA7492 it doesn't look like it. Do they
sound worse than a good analog amp?

The class-D amps typically have a series inductance between the
switching elements and the speakers, does that influence transients?
Even a tweeter has already 15-20 microHenry of inductance.

Mat Nieuwenhoven