audio-talk

Ah yes, the ENABL process.

chris661 wrote: ↑Mon Aug 19, 2019 9:24 am Steve, I like your approach here. Keeps the signal chain nice and simple, which is something I've struggled with when going with active EQ/crossovers etc.

Chris

Well, the “grille engineering” approach does seem to work a treat with this particular full range driver. For want of a better description, the speaker grille is made into a shallow slope acoustic eq setup. Get the slope of the acoustic filter to start at the right point and to be the inverse of the rising response shape from that entry point and your FR driver, should be nicely eq’ed.

I think doing things in front of a speaker with passive components is an under-researched area of audio, and any contribution is very worthwhile.
If you think of how you might be able to kill some high frequency break-up modes around the edge of light-coned drivers, there must be ways of applying annular 'mixers' or 'phase modifiers' near the cone, for instance, haven't had enough time to try out ideas myself.

IslandPink wrote: ↑Tue Aug 20, 2019 9:06 pm I think doing things in front of a speaker with passive components is an under-researched area of audio, and any contribution is very worthwhile.
If you think of how you might be able to kill some high frequency break-up modes around the edge of light-coned drivers, there must be ways of applying annular 'mixers' or 'phase modifiers' near the cone, for instance, haven't had enough time to try out ideas myself.

Engineered grilles are most likely, under-researched because of the prevailing fashion for no grilles; something that has remained the orthodoxy for the last thirty years at least. But that shouldn’t stop us DIYers from playing with different structures. There’s certainly plenty of mileage to be had in this field of endeavour, with single full range drivers.

I vaguely remember the famous magazine article on OB by the man who invented Q57’s the resistance of baffle was key in the design

IslandPink wrote: ↑Tue Aug 20, 2019 9:06 pm I think doing things in front of a speaker with passive components is an under-researched area of audio, and any contribution is very worthwhile.
If you think of how you might be able to kill some high frequency break-up modes around the edge of light-coned drivers, there must be ways of applying annular 'mixers' or 'phase modifiers' near the cone, for instance, haven't had enough time to try out ideas myself.

There are. That's what real phase plugs are (not the bullet / whatever shaped extensions to the pole-piece that are usually called such).

Cressy Snr wrote: ↑Tue Aug 20, 2019 9:37 pmEngineered grilles are most likely, under-researched because of the prevailing fashion for no grilles; something that has remained the orthodoxy for the last thirty years at least. But that shouldn’t stop us DIYers from playing with different structures. There’s certainly plenty of mileage to be had in this field of endeavour, with single full range drivers.

True. There are a few commercial exceptions though; it just doesn't tend to get advertised all that much. Avalon speakers for example have always been designed to be used with the grills on, since they're not 'just' grills; they're lined with shaped damping material to help control diffraction and adjust the polars. Several Wilson speakers have been designed for use with the grills on as I recall. Same for the production versions of the MA-Sota multiways I was responsible for, and most BBC speakers (+ their descendents) after about 1970.

IslandPink wrote: ↑Tue Aug 20, 2019 9:06 pm I think doing things in front of a speaker with passive components is an under-researched area of audio, and any contribution is very worthwhile.
If you think of how you might be able to kill some high frequency break-up modes around the edge of light-coned drivers, there must be ways of applying annular 'mixers' or 'phase modifiers' near the cone, for instance, haven't had enough time to try out ideas myself.

I like reading old hifi books. A mine of info in my view, although the terminology has changed over the years they are a valuable source

That they are. As Tom Danley once complained, 'the ancients keep stealing all my best ideas'.

As far as speakers are concerned there was pretty much nothing W.E., RCA, Stromberg & others didn't do, apart from digital, network synthesis design method and some of the material developments of the past 50 years. That's what happens when you get some of the best engineers in the world and give them a more or less unlimited research budget. We're all just playing catch-up.

As far as speakers are concerned there was pretty much nothing W.E., RCA, Stromberg & others didn't do, apart from digital, network synthesis design method and some of the material developments of the past 50 years. That's what happens when you get some of the best engineers in the world and give them a more or less unlimited research budget. We're all just playing catch-up.

So what came first: the missing digital technology that forced brilliant engineers to use grilles for flattening the response of drivers at certain frequencies or because using grills for this purpose would truly sound better?

For companies that sell speakers it would make sense as they want their speakers to sound perfect without DSP unless they sell active speakers with built-in DSP.

But I wonder if even the most sophisticated speaker grill solution could achieve what can be easily done with a DEQ for example with a few simple steps of setting the parameters?

I would think that adding the effect of a mechanical filter after a mechanical cone breakup would be hard to do in DSP on the input side. But much is possible. Guitar cabinet simulation involves mimicking the effect of cone breakup. Cant help thinking it would take more than a simple filter curve.

To control mechanical cone breakup would need a tiny mic mounted on the cone which measures the velocity/acceleration and sends back data for controlling the amp. I have such a thing in my active Velodyne sub.

But I was thinking rather along the lines of this discussing like taming some small frequency bands of single driver speakers which produce different results at different volumes and at different listening angles. It's frequency related but at the same time very much depending on the volume.
At lower volumes it still can sound ok but at higher volumes it can get too much. DSP that would simply reduce the amplitude of this frequency band would make it sound bad at lower volumes. A dynamic EQ would only lower the amplitude of the frequency band if the volume hits a preset threshold. Works absolutely unnoticed in the background.

Wolfgang wrote: ↑Wed Aug 21, 2019 10:59 pm
So what came first: the missing digital technology that forced brilliant engineers to use grilles for flattening the response of drivers at certain frequencies or because using grills for this purpose would truly sound better?

Well, mechanical methods of adding damping or other forms of loading via plugs, plates &c. came decades before digital made its way into audio (and indeed dates from almost the inception of moving coil drive units; arguably earlier). So it was not a question of whether mechanical methods sounded better or not, but the fact that this was the only available approach, and would remain so until the advent of high speed electronic computers.

Wolfgang wrote: ↑Thu Aug 22, 2019 1:46 am To control mechanical cone breakup would need a tiny mic mounted on the cone which measures the velocity/acceleration and sends back data for controlling the amp. I have such a thing in my active Velodyne sub.

Not quite.

Feedback-controlled subwoofers rely on the cone acting as a piston. ie, what's happening in one place is what's happening all over the cone.

For full-range drivers like these, the cone(s) will be bending all over the place. Correcting for that by altering the signal at the voice coil would be immensely difficult.

Chris

For full-range drivers like these, the cone(s) will be bending all over the place. Correcting for that by altering the signal at the voice coil would be immensely difficult.

You are right. I was under the impression that Backes& Mueller active speakers would have used in the 90ies already some control mechanism for their midrange drivers but it was only for the bass drivers. As far as I know some commercial sound systems are using already controlled drivers even at higher frequencies using "Fuzzy logic". This can predict the expected membrane movement fast enough/in advance so that the amplifier can react before the membrane moves out of control.