Speed controlled Volume

Rob · 02-02-2003, 04:59 PM

I have a slight problem, at slow speeds my engine is nice and quite, no problem, I can happilly play my tunes at a sensible volume. However when I put my foot down, the noise level goes throught the roof, sure the stright through exaust & induction rar are nice, but it meens I have to crank my tunes up to hear them.

Not a problem, the sound system can produce more noise than my ears can take. But when I ease of the power the stereo is too much for my tender little ears.

Now as I'm very lazy, and adjusting the volume is too much like hard work. Does anyone know of a of a speed (well rev would be better) controlled volume control. Which will go between the head unit and amp(s)

I was toying over the idea of building one, based on a modified digital rev meter, a few opp amps and a bit of magic. Howevr if a ready made one exists then all the better.

Ashlawn Kemling · 02-02-2003, 10:10 PM

The Ford Focus' actually have this feature. Really cool. Might try going to a junk yard and ripping it off one or ordering the part and modifying it. Worth a try!

--Ashlawn

Alphared · 02-02-2003, 11:04 PM

well those cars that have it uses a mic to pick up noise level of the cabin. the more noise inside the cabin, the higher the stero volume. alot of new cars have it.

Zip-Lock · 02-02-2003, 11:29 PM

My Malibu has this feature too. It doesn't have the functionally anymore because it only works with the factory head unit. I almost immediately ripped out the factory head unit after I bought the car, so I never got much of a chance to see how well it worked.

The factory head unit has a VSS (vehicle speed senor) input and automatically turns up the volume as your speed increases.

digitalww · 02-03-2003, 12:06 AM

Few years back I had a JVC chameleon (the first model that came out) and it had that exact function. When your RPMs go up so does the amount of juice your alternator puts out and it would sense that and adjust the volume accordingly.

magnetik · 02-03-2003, 01:06 AM

Quote:

Originally posted by digitalww
Few years back I had a JVC chameleon (the first model that came out) and it had that exact function. When your RPMs go up so does the amount of juice your alternator puts out and it would sense that and adjust the volume accordingly.

that seems like the best method.... I know a mate was successfully turning an old PC into a rev gauge a few years back, basically hooking up from the ignition system to a pin on the printer port (with some middle hardware too - remember printer ports are only 5V!) and then monitor the number of clicks on the printer port...... something like that sounds very doable...

mp3z24 · 02-03-2003, 01:59 PM

Quote:

Originally posted by Alphared
well those cars that have it uses a mic to pick up noise level of the cabin. the more noise inside the cabin, the higher the stero volume. alot of new cars have it.

that is completely untrue...

if you have a mic in the cabin... then it would pick up the radio noise, and increase the radio output to drown out the "noise" it picked up. that would mean that it would keep getting louder until the volume is maxed out, the speakers blow, the car is turned off... etc.

the real way that speed controlled volume works, is that the vehicle computer is linked to the radio. in late model GM vehicles, this is known as class 2 data wiring. basically, the computer relays a electrical signal to the radio, which it decodes and from that signal, it knows the speed of the vehicle. from this information, the radio increases the volume to cover the road/engine/wind noises. typically, there is a setting that can be toggled between off/low/med/high so that the driver has final say in whether or not the SCV is on, and at what rate the volume increases.

that same class 2 data wire is why late model cars can have radios that remain on when the car is turned off and the key removed. the computer is essentially flipping a relay to turn on and off the power to the deck....

this is also the reason that 99% of the radio installation shops throughout the US will NOT install radios in many late model GM cars. not because it is impossible.. far from it. but is it just that they do not understand the electronics involved.

~mike

Alphared · 02-03-2003, 10:58 PM

Quote:

that is completely untrue...

if you have a mic in the cabin... then it would pick up the radio noise, and increase the radio output to drown out the "noise" it picked up. that would mean that it would keep getting louder until the volume is maxed out, the speakers blow, the car is turned off... etc.

Oh really, someone should tell nissan & Bose then, cause in the 350z, bose system uses AudioPilot Noise Compensation Technology, which have a mic under the steering wheel to pick up cabin noise and increase/decrease volume.

also, in the prelude, they have mic to do the same.

Don't believe me, check it out for yourself:

http://www.bose.co.uk/product/auto/a...lot_tech.shtml

Don't rule out technology just cause you never heard of it!

Birrman54 · 02-04-2003, 12:45 AM

Quote:

Originally posted by Alphared
Oh really, someone should tell nissan & Bose then, cause in the 350z, bose system uses AudioPilot Noise Compensation Technology, which have a mic under the steering wheel to pick up cabin noise and increase/decrease volume.

also, in the prelude, they have mic to do the same.

Don't believe me, check it out for yourself:

http://www.bose.co.uk/product/auto/a...lot_tech.shtml

Don't rule out technology just cause you never heard of it!

he does have a valid point though, I'd be interested to know how it distinguishes between engine noise and actual music or speech inside the car.

Wouldn't it be easy enough to setup a noise cancellation system that would sample engine noise and play the reverse in the cabin so the noise cancels out?

birrman54

Alphared · 02-04-2003, 08:33 AM

It acts like a noise canceling headset. It takes all the noise from the cabin (ambient and stereo) and filters it then goes into a compensation filter which up the volume if ambient is higher than stereo. Since its part of the system, It can tell whats noise and whats coming from your stereo (like the headset). check the bottom of that link, i'll tell you how they do it.

This is more effective than speed volume change cause what happens if you have the window down or up, how can it tell how much noise is in the cabin?

albysure · 02-04-2003, 06:13 PM

throw some dynamat or something equivalant in there and you'll be all set!

cproaudio · 02-04-2003, 11:54 PM

Quote:

Originally posted by Alphared
also, in the prelude, they have mic to do the same.

From what I understand, in the prelude's system, the mics are under the speakers. It detects distortion. If it senses distortion, it automatically cut down the amount of wattage going to the speakers.

mp3z24 · 02-05-2003, 10:08 AM

Quote:

Originally posted by Alphared
Oh really, someone should tell nissan & Bose then, cause in the 350z, bose system uses AudioPilot Noise Compensation Technology, which have a mic under the steering wheel to pick up cabin noise and increase/decrease volume.

also, in the prelude, they have mic to do the same.

Don't believe me, check it out for yourself:

http://www.bose.co.uk/product/auto/a...lot_tech.shtml

Don't rule out technology just cause you never heard of it!

well... to be a smart ***... that is not exactly speed controlled volume

the bose system that you linked to is simply an audio system that uses noise cancelation technology to alter the sounds played by the stereo to cancel out the unwanted sounds. effectively maintaining the volume in the cabin at the predetermined user selected level.

see the explanation on the last page...http://www.bose.co.uk/product/auto/a...ot_tech6.shtml, the volume remains the same regardless of vehicle speed.

there is a LOT of technology involved here, and it is a nice little system that they have designed... different than speed controlled volume. this is like the sophistiacted approach, while cranking up the radio automatically to cover road/engine noise is more of a cheap and crude method...

~Mike

Callahan · 02-05-2003, 10:28 AM

My Grand Am has this feature, but I really hated it. I found the volume was changing way too often (maybe because of my lead foot

). Even though the head unit has three settings for how much the volume will change, it was still too extreme. Maybe just the Delco version is crap, but I turned it off a day after I got the car.

Technics · 02-12-2003, 06:48 AM

It'd be easy to to make a system to distinguish between the stereo and cabin noise. All the system has to do is subtact the audio signal it is sending to the speakers from the audio it picks up from the mike (the more you turn it up the more it will subtract, cancelling the stereo). You'll be left with the external noise only. You'd just need to calibrate it with the engine off in a quiet environment so it subtracted the the right amount to nullify the stereo. It'd only take a couple of opamps.. you'd probably want to make it slightly slow to respond so it didn't increse the volume too much when your car backfires

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