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Thanks for sharing your insight, Rob45. It's good to know the TPS input proved useful (I was going to use MAP, but may look at both now). Do you happen to know if (a) these systems used some passive noise control as well, or just active, and (b) if the failure to cancel harmonics was due to...

Turn it off? ... that's only slightly tongue-in-cheek: have you heard a Prius go by ... eerie! Maybe you could tell us what "inaudible" is to you ... what environment will this run in? Cheers, Rod

Thanks Snowrat. IIRC, the Lueven work uses a variable restriction rather than noise cancellation. To my mind this reduces the benefits of active noise control on a silencer (muffler) because backpressure is probably the last thing you want on an IC engine. I don't doubt it could be made to work...

I guess you won't be using 15kW for long ... have you considered charging a bank of 20x 12V lead acid batteries using a lower power rectifier, and then using the batteries to get you over the surge requirements? HTH Rod

Hi, does anyone have sample circuits for what GM calls "GAL". ie: automatic volume control in a vehicle, to compensate for road noise as the speed increases. I had some ideas about hooking an F-V converter to a VGA but before I go reinventing this, I though I'd ask you guys. I gather...

Are you saying I should also take MAP or TPS as well as RPM? Teaching the system this transient behaviour may be difficult, no? I suspect using a fuel injector's signal pulse won't work under all conditions. Although it has variations in both pulse width (load) and frequency (like the tacho)...

Thanks for bringing up the idea of a resonator - from what I've read these are not as good as ANC because they only deal with one frequency per resonator (making it very complex for signals other than tones). I'll be trying to make the ANC work if I can. Cheers, Rod

Hi, may I ask if there's any auto engineers who can contribute to this: thread384-75898

Hi, may I ask if there's any EEs who can contribute to this: thread384-75898

There's many out there, this one's fairly concise: http://www.its.bth.se/courses/etc004/fxlms.pdf One of the key things is, this algorithm can take the crank angle sensor as input, avoiding a microphone in the worst (hot) part of the exhaust system. The crank angle sensor should be noise free...

Hi everyone. I'm in the process of building up an active silencer for a typical mid-size car. Has anyone had any experience with doing this before and can reveal tips/gotchas to help get this project off the ground? The first prototype will be added to a typical "high flow" (read...