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Reverse-engineering my speakers' API to get reasonable volume control

jamesbvaughan.com

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Re: Reverse-engineering my speakers' API to get reasonable volume control

#131
post #18

I love this type of posts, and I’m amazed the speaker exposes its API like this. The kid in me thinks there could also be a way perhaps to transmit audio through this (or another) API? (very low chance, but…)

From his filesystem listing in the post it looks like you can overwrite firmware update data. I wouldn't be surprised if you can make it play or capture whatever you want be overwriting the firmware.

Re: Reverse-engineering my speakers' API to get reasonable volume control

#132

Earlier quoted context omitted.

> Volume controls also shouldn't just be a flat wideband gain - they should respect how we actually perceive sound so the timbre doesn't change as the level changes (when you turn the volume down, you are typically left with just the stuff in the vocal frequency range, and lose all the bass etc). The amp I'm upgrading from was interesting in this regard. In addition to the main volume knob, it had a loudness knob. Th…

Amazing. This is probably the correct way do make amp controls. I'd say the volume should be a multi turn trim potentiometer in the back of the device so you don't have to brief your guests on correct operation.

Yes, a stepped attenuator.

Re: Reverse-engineering my speakers' API to get reasonable volume control

#133

Earlier quoted context omitted.

Quality of active speakers are really good these days, they have matched amps and speakers from neumann, genelec etc also has active crossover which is superior than any passive setup. Mature market sure, but even companies like KEF who didn't offered or focussed much on active systems, have growing range of options now.

Nobody is arguing their quality is bad, but that amps die long before speakers die. Do passive speakers even die? Also, online services built into these will die before the speakers do.

You can see >30 year old Genelec 1031A all around the world in perfect working order. Their die cast aluminium models using the whole box as heatsink should be able to last even longer, theoretically.

I'd say active (especially digital active) is too much of an improvement to pass up, but if you only want to talk about waste and reliability, try to find about support and spare parts company policy. Some prestigious passive brands like Revel have some forum horror stories about lack of spare parts for 10 year old models that barely got discontinued while Genelec says https://www.genelec.com/product-warranty-lifetime

Also, as someone mentioned, advanced (thermal based) limiters saving tweeter voice coils.

Disclaimer: I am a fanboy owning a pair of 8341A.

Re: Reverse-engineering my speakers' API to get reasonable volume control

#134

This begs the question, why buy oversized speakers of which you can only use 10% of the range instead of smaller speakers? Is the sound quality better when not approaching to maximum volume?

These are complexly related parameters. All else being equal:

- a larger enclosed volume produces lower frequencies more efficiently

- a larger Xmax (range of motion) on a conventional driver produces louder sound

- a smaller Xmax produces less distortion

- a larger driver area produces louder sound

- a larger driver area can produce more distortion unless the engineering compensates for that, which usually involves more expense in materials and assembly

- the more efficiently coupled a driver is with the room air, the less distortion results

- there are several ways to improve the coupling of a driver to the room air, all of which increase one or more of cost or complexity or size

- larger and/or more complex cabinets cost more than smaller and simpler ones

- adding drivers to a speaker increases complexity

If we had perfect materials, we might build a single driver speaker made of infinitely stiff material of zero mass that accelerates/decelerates infinitely quickly in response to exactly enough power to overcome air pressure, and the parameters we would still have to tweak would be size (to control maximum sound pressure level) and whether we wanted to place it in front of an infinitely sound-absorbing back wall (to change it from an omnidirectional source to a cardioid source).

We don't have any of those things, so for a given budget of price, size, parts availability and complexity we need to make tradeoffs to get to our targets for loudness and quality; not all targets can be reached from a given constraint.

TL;DR: yes.

Re: Reverse-engineering my speakers' API to get reasonable volume control

#135

Earlier quoted context omitted.

Which one did you make?

This one is my make: https://www.printables.com/model/908684-spacemouse-mini-slim...

Ah right, the one I was thinking of was this one which seems like a bit more work... https://www.youtube.com/watch?v=iHBgNGnTiK4

Yours looks great too, though, and it seems a lot more accessible than the fancy one. :)

Re: Reverse-engineering my speakers' API to get reasonable volume control

#136
post #135

Earlier quoted context omitted.

This one is my make: https://www.printables.com/model/908684-spacemouse-mini-slim...

Ah right, the one I was thinking of was this one which seems like a bit more work... https://www.youtube.com/watch?v=iHBgNGnTiK4 Yours looks great too, though, and it seems a lot more accessible than the fancy one. :)

Ah yeah, that's much more work and I don't think it uses the official driver, which does a lot of the heavy lifting. I think maybe start with the other one and see how you like it, since it's mostly a few minutes of soldering.

Re: Reverse-engineering my speakers' API to get reasonable volume control

#137

Earlier quoted context omitted.

"So they don't damage users' speakers, their hearing, or generally cause annoyance." Damage speakers? Simply, not an issue unless they're one step removed from rubbish. Also, have you ever heard of output compression and clipping that would protect them? That approach is 101 electronics. Hearing is not an issue as they're driven by flea power (they're not headphones). Even hearing these pissy little speakers when run…

> Damage speakers? Simply, not an issue unless they're one step removed from rubbish. Also, have you ever heard of output compression and clipping that would protect them? That approach is 101 electronics. Output clipping actually increases power at high frequencies. So your 2003-era Japanese radio has better output than a Chinese laptop. > are not fit for purpose when it comes to the audio subsystem Consider the pos…

[deleted]

Re: Reverse-engineering my speakers' API to get reasonable volume control

#138

Earlier quoted context omitted.

"So they don't damage users' speakers, their hearing, or generally cause annoyance." Damage speakers? Simply, not an issue unless they're one step removed from rubbish. Also, have you ever heard of output compression and clipping that would protect them? That approach is 101 electronics. Hearing is not an issue as they're driven by flea power (they're not headphones). Even hearing these pissy little speakers when run…

> Damage speakers? Simply, not an issue unless they're one step removed from rubbish. Also, have you ever heard of output compression and clipping that would protect them? That approach is 101 electronics. Output clipping actually increases power at high frequencies. So your 2003-era Japanese radio has better output than a Chinese laptop. > are not fit for purpose when it comes to the audio subsystem Consider the pos…

"Consider the possibility that they're fit for a purpose other than yours."

I have, and I'm not alone. With the possible exception of Apple, there's ample evidence that for decades many, many laptop owners have complained about the horrible and inadequate sound in laptops. As Apple hardly represents much competition to Windows, manufacturers of Windows PCs don't have enough incentive to fix the problem, if all their offerings are essentially the same then there's obviously no need.

"…a Chinese laptop"

…And a Dell, it's American if you recall (even if made in China it has to be made to Dell's specifications).

"Output clipping actually increases power at high frequencies."

Nitpicking over omissions in HN comments is unbecoming as most posters 'shortcut' comments out of necessity. Had I not limited my reply and I'd expanded it then my comment would have been considerably longer and much more detailed.

I'd have had to make mention that clipping done for the purposes of limiting output power often (but not always) involves 'soft clipping' circuity, as it's purposely designed to limit the energy contained within high frequency components generated by clipping.

Moreover, I could have gone even further and explained that (a) such circuitry is often done before the output stage to protect both it and the load (here, the speaker), (b) in addition I could have provided the Fourier math and related calcs to show the extent and effectiveness of said protection.

Oh, and there's even more: a comprehensive report would also require (c) knowledge of typical (nominal) audio signals inputted into the amplifier, and that would have to take into account distortions including intermodulation products introduced by compression and soft-clipping processes, as they significantly alter the power versus frequency spectrum of the output signal. If of a significant level we'd also have to include distortion products introduced by the output stage into our calculations.

There's even more, (d) we need to know the speaker's maximum power handling capacity (power versus frequency rating) to protect both the speaker, and (e) to determine whether the combined distortion/intermodulation products including those generated by speakers driven at or above their maximum rated output are tolerably acceptable to end users/listeners (listeners usually find HF intermodulation distortion artifacts produced under such conditions highly objectionable).

…And there's even more factors to consider but I'll dispense with them for now.

Having to provide such a detailed response to a general point to deter pointless nitpicking is simply madness, nevertheless it's the logical outcome if it's pursued. A question, have you ever designed and built any such circuits, or do your comments come from purely theoretical understandings?

Perhaps, just possibly, your continued hostility towards acknowledging the existence of a very common problem experienced by many PC users comes from the fact that you might be involved with an organization that—at least in part—is responsible for its creation.

Re: Reverse-engineering my speakers' API to get reasonable volume control

#139

Earlier quoted context omitted.

> Damage speakers? Simply, not an issue unless they're one step removed from rubbish. Also, have you ever heard of output compression and clipping that would protect them? That approach is 101 electronics. Output clipping actually increases power at high frequencies. So your 2003-era Japanese radio has better output than a Chinese laptop. > are not fit for purpose when it comes to the audio subsystem Consider the pos…

"Consider the possibility that they're fit for a purpose other than yours." I have, and I'm not alone. With the possible exception of Apple, there's ample evidence that for decades many, many laptop owners have complained about the horrible and inadequate sound in laptops. As Apple hardly represents much competition to Windows, manufacturers of Windows PCs don't have enough incentive to fix the problem, if all their…

> Perhaps, just possibly, your continued hostility towards acknowledging the existence of a very common problem experienced by many users comes from the fact that you might be involved with an organization that—at least in part—is responsible for its creation.

To be clear, I am speaking only in a personal capacity.

"Most laptop sound systems suck and I don't use them." - Marsh Ray

Re: Reverse-engineering my speakers' API to get reasonable volume control

#140

Earlier quoted context omitted.

"Consider the possibility that they're fit for a purpose other than yours." I have, and I'm not alone. With the possible exception of Apple, there's ample evidence that for decades many, many laptop owners have complained about the horrible and inadequate sound in laptops. As Apple hardly represents much competition to Windows, manufacturers of Windows PCs don't have enough incentive to fix the problem, if all their…

> Perhaps, just possibly, your continued hostility towards acknowledging the existence of a very common problem experienced by many users comes from the fact that you might be involved with an organization that—at least in part—is responsible for its creation. To be clear, I am speaking only in a personal capacity. "Most laptop sound systems suck and I don't use them." - Marsh Ray

Fine. I agree, let's leave it at that. :-)
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