The Minimus 7 are speakers that I will never, never, never replace with any other, no matter how much fame any competitor may have or how much I will be pushed for.
Never heard of a coil for cone motion feedback before. Interesting.

 

Never heard of a coil for cone motion feedback before. Interesting.

Sounds like a marketing gimmick to me.

 

Sounds like a marketing gimmick to me.

It's not.
Why do you think it is?
It's no different than other forms of feedback used to improve a system's performance.
Motion feedback, such as adding an accelerometer to the cone or servo-control, is used to reduce the distortion and improve the frequency response of subwoofers.
The added winding also provides that feedback.

 

As a matter of fact, when Philips Electronics was still in the consumer electronics market, had a similar servo-controlled subwoofer. Circa 1980. They had impressive bass in a small enclosure.

 

It's not.
Why do you think it is?
It's no different than other forms of feedback used to improve a system's performance.
Motion feedback, such as adding an accelerometer to the cone or servo-control, is used to reduce the distortion and improve the frequency response of subwoofers.
The added winding also provides that feedback.

https://www.rythmikaudio.com/technology.html

It works at low power before the small cone starts to deform, causing higher order distortion.

Me, I like earth moving bass even at low sound levels, for that you need transducers that can push a lot of air or move mass at low or high power levels.
4, 12 inch subs bridged with 1000W RMS and 500W RMS for tactile transducers on a isolated Riser sitting platform.
https://forum.allaboutcircuits.com/...st-dedicated-home-theater.160250/post-1398002




Riser response after equalization


Total room response. This comes from more than just speakers, amplifiers and electronics that do help to round the corners a bit, it's the mainly from the pre-wired, braced structure, over-stuffed and damped room, designed for good sound. The good room makes a cheap boombox sound good.

 

It works at low power before the small cone starts to deform, causing higher order distortion.

Mine has a 12" stiff cone that doesn't significantly distort unless seriously overdriven (which I have never observed).
It's able to generate observable shaking of my sofa for large, low-frequency movie special effects sounds that I only partially hear, and it's located in a large open basement room.
It's quite adequate for my needs.
You obviously have a great system, but that would be overkill for me.

 

Mine has a 12" stiff cone that doesn't significantly distort unless seriously overdriven (which I have never observed).
It's able to generate observable shaking of my sofa for large, low-frequency movie special effects sounds that I only partially hear, and it's located in a large open basement room.
It's quite adequate for my needs.
You obviously have a great system, but that would be overkill for me.

No such thing as overkill for our pleasure. That's a nice speaker you've got.

 

I passed up a $30 pair of 7s at our local goodwill this past weekend.

They were (externally) perfect condition. I held them in my hands with deep nostalgia, then realized I had no use for them.

Changed my mind and they were still there. Got 'em



Tested out fine. They sound brand new.

'84 date code, BTW. Good year.

 

OK, golden eared folks, I can hear serious distortion, but I never push the speakers to where they add any that I can hear. And certainly my taste in music must be rather different. And in a free society I would not have it any other way!!
As for adding a feedback coil to somehow improve the sound, certainly it is an interesting concept. But considering that it was probably providing velocity feedback, and considering that a coil moving in a magnetic field generates a voltage depending the VELOCITY, it seems rather useless if the speaker drive characteristics are adequately known. So the feedback would provide the most improvement to the poorest quality speakers.

 

OK, golden eared folks, I can hear serious distortion, but I never push the speakers to where they add any that I can hear. And certainly my taste in music must be rather different. And in a free society I would not have it any other way!!

I just like wide dynamic range. I want the voices to be crystal clear and the booms/LFE/bass to be distinct and not clipped. That takes sizable power to listen at movie theater/concert levels. I want at least 3dB headroom at the loudest levels I listen too. A I've got lots of 24-bit 96kbs master recordings in DTS 5.1 and other encoding types.

I need a sound system that can reproduce what they can deliver without compromise or stupid Golden Eared extravagance.

 

Changed my mind and they were still there. Got 'em

View attachment 350284

Tested out fine. They sound brand new.

'84 date code, BTW. Good year.

Excellent study or office speakers. Wise choice.

 

But considering that it was probably providing velocity feedback, and considering that a coil moving in a magnetic field generates a voltage depending the VELOCITY

Exactly. I think you are DSP territory to make use of it. Perhaps they actually do that and use a PID algorithm to control the cone position, but lt somehow I doubt it.

In addition to that, the feedback will be non-linear since the field will not uniform, with the largest errors being at the extremes where it is most needed.

I cannot believe that money spent on that would not be better utilized in a better driver until you got to the very highest levels of price and performance.

 

Excellent study or office speakers. Wise choice.

I sold hundreds of these in the 80s. They are dripping with nostalgia.

 

a coil moving in a magnetic field generates a voltage depending the VELOCITY,

Certainly you can get position from the velocity signal, and also allow for any non-linearity in the magnetic field.
These days, it's not difficult or expensive to do this with DSP, if needed.

I cannot believe that money spent on that would not be better utilized in a better driver

Believe what you will.
The driver used is high quality with the feedback used to further improve the quality of the output, not to improve the output of a poor driver.
Certainly the extra money for the added winding and control circuitry can't be that significant compared to the cost of a good speaker.
Works very well for me, with low frequency bass, no boominess and more than sufficient output.

Here's a discussion of the technique if interested.

 

Funny thing is, large bass speakers get better with age, like fine wine and old geezers.
They get softer around the edges and grow more mellow.

 

Funny thing is, large bass speakers get better with age, like fine wine and old geezers.
They get softer around the edges and grow more mellow.

According to one musician friend of mine, the speakers and every other part of the sound system, especially the amplifier, all wear out. Of course, that musician's technical education is less than my friends cat's technical education.
Certainly though, speakers can be damaged by abuse, including over-driving them with excess power.

 

Funny thing is, large bass speakers get better with age, like fine wine and old geezers.
They get softer around the edges and grow more mellow.

Yea, until they fail completely and need a foam ring replacement like my CV DX-9s did.

 

This reduces distortion, and extends and flattens the frequency response, eliminating the peaking and resulting boomy sound typical of many ported subwoofers.

So does a properly tuned port, with higher efficiency.

 

So does a properly tuned port, with higher efficiency.

Don't agree.
The transient response is not as good.
And I don't see that "efficiency" is a significant concern for subwoofers.

But, for some reason, you have a bug about woofers with motion feedback so I guess there's really nothing more to say.

 

But, for some reason, you have a bug about woofers with motion feedback so I guess there's really nothing more to say.

No, I am interested. Does the one you have use analog circuitry to convert the velocity feedback to positional, or a DSP, or something else? the link you gave was promoting a subwoofer driven by a servo motor!!! Now that is different, the feedback is directly related to position, unlike a feedback coil on the woofer.