Speed based dynamic volume adjust??

I didnt see this in the FAQ so hopefully this is a new idea..

I dearly miss my facotry stereo's ability to adjust the volume automatically and dynamically based on the speed I was traveling. I was a very handy feature that had an adjustable setting to determine the range and sensitivity of the feature, that would slowly increase the volume as you sped up, and decreased it as you slowed down.. It was great in my convertible when the radio was blaringly loud at stoplighs, but perfect at cruising speeds...

I did some research on how the circuitry accomplished this, and discovered that the head unit monitors the voltage ripple on the 12v supply line to determine how quickly the alternator is turning. The volume can then be easily adjusted because the mechanism is inside the head unit.

Is something like this feasible on the Empeg??? Or perhaps some sort of alternative sensing device connected via the USB/serial ports connections?

There was a discussion about this on the bbs before. I don't know if anything came of it, but you can do a search for "speed controlled volume" and see for yourself.

ah yes.. there it is..

Interesting read... It seems to have evaporated around December of last year..

fwiw, I defenitely thing the GPS route for speed determination is the wrong way to go. No other currently existing products, that all work amazingly well use this technique. Even boat stereo head units utilize the alternator noise method...

-shrug-

I sure hope this makes it to the light of day

Hi!

I still have that idea in my mind. I ordered a few digital potentiometer (DS1803 from maxim / dallas semi) that could be used in-line between the emepg and my amps. Unfortunatly, I won't have much time in the next few months to launch the project, but certainly after summer. I also think GPS is overkill for this application. I'll keep the bbs informed if I come up with an interesting design.

Patrick

discovered that the head unit monitors the voltage ripple on the 12v supply line to determine how quickly the alternator is turning.

The empeg doesn't have any way to monitor the voltage ripple on the 12v supply line that closely (as far as I know). However, it has lots of other inputs which could be used for something similar. For instance, a small interface board could grab the current speed from the OBD-2 computer in the car and feed that to the empeg through the serial port.

Something else to consider is that the player has a microphone input. I think using this microphone input would be a much better way of adjusting volume on the player, because you could adjust based on actual road noise instead of speed. My last set of comments on this subject are here, where I outline why I think this would be a better way of doing it. It would require that you mount a small cheap microphone somewhere outside the car (such as in a wheel well, or behind a bumper, or some such) so that the music playing on the interior of the cabin didn't affect the sampling. The beauty of this would be that it could be done entirely in the Hijack software, there would not be any interface boards needed. So it's just a coding project. (The user could supply his own mic hardware. I've got just the one, in fact, it's a really tiny cheap little mic that came with a really old sound card. Smaller than my thumb, I could mount it anywhere on the vehicle I wanted.)

In other words, what you're talking about is do-able, it's just that no one has done it yet. I think that the main problem with this project (and with a few other projects like it) is that the people with the ability to do the work aren't the same people as the ones who want the feature for themselves.

In order for a "pet project" like this to get off the ground, you need to have someone in which the two "sets" intersect: Ability and desire. Brian made backlit buttons because he wanted them for himself. Jan made GPSapp because he wanted to get route directions on the empeg screen. Mark made Hijack because... well... I don't know why Mark made Hijack (but I'm really glad he did).

I was talking to Hugo about this last night, and he reckons that the cellphone mute line can also be used to sample a pulse-encoded speed signal. It would require a kernel driver (or some Hijack work), but it's theoretically do-able.

Mark made Hijack because... well... I don't know why Mark made Hijack (but I'm really glad he did).

Mark made hijack to boost his post count, i remember reading that somewhere.

Mark made hijack to boost his post count, i remember reading that somewhere.

And they say that displaying the post count has no benefits...

/Michael

I was asking that question too and am still very enthusiastic about it. But as was mentioned before, my ability is somewhat lacking...
Here's the link to ye olde thread.

Something else to consider is that the player has a microphone input. I think using this microphone input would be a much better way of adjusting volume on the player, because you could adjust based on actual road noise instead of speed.

I agree.. i think that the microphone input could be used to provide this function, however i think that rarther than mounting the mic outside the vehicle to monitor noise, it would be better to have the mic inside the car, then have the empeg subtract it's output audio from the mic input signal - the resulting signal would be the noise heard inside the car (more or less). The amplitiude of this signal could then be used to control the volume boost/cut.

Does this sound possible?

RichieC

it would be better to have the mic inside the car, then have the empeg subtract it's output audio from the mic input signal

This would be tricky to do correctly and there would need to be a lot of work done in the software to accomplish it. It would have account for things like L/R delay, EQ, mic placement, etc. It's not a simple X-Y operation in the software, it's a lot of work. By making the assumption that the mic isn't hearing the music, you simplify the software.

Not that it really matters right now whether the software is simple or complicated. No one has stepped up to actually claim the project yet.

Thats why I am sticking with my standard head unit in the truck, well, that and onstar compatibility.
But at least the onstar problem has a (not inexpensive or elegant) workaround with an extra amp/speaker combo.

I actually got to use onstar last week after I locked my keys in the car and got them to remote unlock it. It worked even 7 floors down in a multistorey parking lot. The doors unlocked just as they called me on my cellphone to confirm it worked, very nice.

Interestingly, the speed based adjust works when you are talking to onstar as well. I mention this because the separate amp workaround can't do that either.

I actually got to use onstar last week after I locked my keys in the car and got them to remote unlock it.

How were you able to press the OnStar button while standing locked outside the car?

How were you able to press the OnStar button while standing locked outside the car?

Here's how

So you have to call on a different phone? How do they authenticate you? Name + PIN?

I was gonna guess, though, that it had something to do with ginger ale frozen into ice cubes.

We have OnStar on one of our cars (and the prior one). My wife rolled her last car 3 1/2 times and ended upside down in the street. The air bags didn't deploy so no OnStar. It seems to me if your car is upside down, it should call somebody.

So with that in mind, we've ever have even used it. If I remember though you give them your name and address and then the PIN. Which brings up another problem... "uuuuh... I can't remember my PIN".

Ouch! I hope she was ok after that experience?