On 9/11/2019 12:25 am, wrote:
> On Thursday, November 7, 2019 at 4:32:20 PM UTC-5, Trevor Wilson wrote:
>>>
>>> Regarding feedback, I remember there was an hobby project long ago to
>>> have a very small R between speaker and GND (GND also being the amp's
>>> ground), and using the speaker's back EMF as feedback to correct
>>> excursions. There are some later publications from W.Kippel about it.
>>
>> **The first system I saw with that arrangement was the Infinity RS1. It
>> introduced as many problems as it solved. Amplifiers with 'floating'
>> output stages encountered some problems. Bridged amplifiers too. That
>> said, the bass extension available from a rather modestly sized, sealed
>> enclosure was impressive.
>
> May well be the case, but it wasn't because of feedback. If there
> was anything done electronically, it was EQ which, itself, is a
> completely legitimate way of getting bandwidth, if done properly*.
>
> * Which, of course, is subject to Dick Pierce's First Law
> of Acoustics: Anny idiot can design a loudspeaker and,
> unfortunately, many do.
>
>

**True enough. In fact, I've found somewhat excellent results using a
Behringer DCX2496 in place of the original Infinity crossover for these
speakers. The original crossover can be a PITA to integrate with some
systems, due a number of design limitations. The Behringer, OTOH, has
some useful features that make it an excellent, economical substitute.

--
Trevor Wilson
www.rageaudio.com.au