While I sort out what to do, here are some musings on the ACE-BASS circuit...
Looking at Stahl's JAES paper from 1981 it's clear that he uses some feedback from the sense resistor to both create the amplifier's negative output resistance and to simulate the output network in the input network (it's not exactly clear to on how this last one works).
Keeping that in mind, there is also the work from Werner in the late 1950's. Werner used a negative output impedance amplifier to extend and smooth the bass response and lower distortion. Werner explicitly states that a negative impedance is superior to a negative resistance because the latter will cause a high-Q resonance to form with the voice coil inductance in the 500-1kHz range, which is exactly one of the things that Stahl's circuit suffers from.
So, why not combine these two concepts? Stahl makes very clear that the negative output impedance amplifier portion of his circuit is separate from the bandpass filter part, so in theory this should be do-able. By using a negative impedance a la Werner the resonance problem can be reduced or eliminated alltogether, and Werner mentions that his circuit was very stable, which can't be said about Stahl's circuit if Zu ~ Re.
Looking at Stahl's JAES paper from 1981 it's clear that he uses some feedback from the sense resistor to both create the amplifier's negative output resistance and to simulate the output network in the input network (it's not exactly clear to on how this last one works).
Keeping that in mind, there is also the work from Werner in the late 1950's. Werner used a negative output impedance amplifier to extend and smooth the bass response and lower distortion. Werner explicitly states that a negative impedance is superior to a negative resistance because the latter will cause a high-Q resonance to form with the voice coil inductance in the 500-1kHz range, which is exactly one of the things that Stahl's circuit suffers from.
So, why not combine these two concepts? Stahl makes very clear that the negative output impedance amplifier portion of his circuit is separate from the bandpass filter part, so in theory this should be do-able. By using a negative impedance a la Werner the resonance problem can be reduced or eliminated alltogether, and Werner mentions that his circuit was very stable, which can't be said about Stahl's circuit if Zu ~ Re.
No, I eventually gave up on this project after I moved to more DSP oriented signal processing.
It was pointed out to me that the inevitable delay would cause phase lag that would eventually become positive feedback at some frequency, so I didn't pursue that.
ACE Bass
You have everything you need online.
The difficulty is the implementation you have to decide
if you want to make an ACE Bass to add to an existing amplifier
or make a single package.
I tried the first route and it worked in part.
I underestimated the 20hz high pass filter (which I didn't add) and
I regret it.
Still another aspect, for me, unresolved is the bass alignment
B6 type reflex.
let's hear, I'm continuing on the journey.
You have everything you need online.
The difficulty is the implementation you have to decide
if you want to make an ACE Bass to add to an existing amplifier
or make a single package.
I tried the first route and it worked in part.
I underestimated the 20hz high pass filter (which I didn't add) and
I regret it.
Still another aspect, for me, unresolved is the bass alignment
B6 type reflex.
let's hear, I'm continuing on the journey.
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ACE2
I have found this: US4797933A - Bass amplifier with high frequency response
- Google Patents
Ace amp without Ace problems.
I have found this: US4797933A - Bass amplifier with high frequency response
- Google Patents
Ace amp without Ace problems.
Happy Christmas.
I'd be interested in trying something like this.
This could probably extend the
response over 200Hz of ACE Bass.
I don't know how this can be done but I would
like to get an idea of the implementation.
I'm working on a project and I'd like, even if I pay,
to have a standalone DSP ACEBass scheme, i.e. with the
possibility of connecting it to an external amplifier.
Great stuff.
If using DSP, you'll need to use a DSP with ultra low latency (as we are dealing with a fb circuit), like the ADAU1777 or the like.
Search for GRIMM audio MFB sub white papers
https://www.grimmaudio.com/publications/loudspeaker-technique-white-papers/
Search for GRIMM audio MFB sub white papers
https://www.grimmaudio.com/publications/loudspeaker-technique-white-papers/
Baldin beat me to the answer. It's probably not a great idea to try and use DSP unless you really know what you are doing. You are likely to create a feedback loop at some frequency due to the delay within the DSP (delay is a phase shift). I know that is HAS been done before, however, so maybe you can find someone who will work on such a project for you?