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<x-charset iso-8859-1>> Jim Rustad > OK, that would do it, I suppose. Many of us probably have access to a > computer (given that we are using this list). Is a "standard" > sound card not up to the task? What would be a nice > mike? I would guess that one could be obtained with a suitable driver > to do analog-to-digital conversion and the signal would show up > as a file on your computer. Probably even comes with code > to transform the signal into the frequency domian. > > Actually, this must be essentially how a knock sensor works > on modern cars, but maybe over a more limited frequency band? > > well even if it won't work I still want to try. > If you see a strange looking guy wanting to record your engine > at parma, its probably me. > It's drifting off topic but... The trouble with just using a "standard" PC card is that they all do 44.1 sampling, but they don't all do it with the same accuracy, the same sampling range and therefore the same results. Example: you have a Compaq 133Mhz machine that you still use because it works good enough for what you do... fair enough. It has a built in sound card using Crystal 3D drivers. I have a dual PIII-933 with a ATA 100 Raid-0 array, and an Event Darla sound card. It may as well be the difference between tape and CD. That is before we even get to the microphone. To answer your question about the mic, expect to pay about $200+ for a decent microphone for what you want to do. You could certainly do better, but the main thing is to get a very narrow field mic to eliminate other noise. It is commonly referred to as a shotgun mic. I personally like Audio Technica, but another good choice should be Sennheiser (more $) or Sure. On another note, I have to say that since it was brought up, a contact microphone would be much more useful for this test. Now the software is another variable that you probably don't want to get into. That is why I suggest using a DAT or another form of digital hand-held recorder, and the contact method of recording. You'll eliminate a large amount of variables that way. I can't say what a good mic of this type would be. I've never used them. _______________________ Back to the topic (mostly) now: I'd bet that even if you couldn't get the kind of data that could be analyzed by software to show known patterns for sound, the human ear could do it just fine. A nice baseline set (20 I think was a number thrown out already) of good engines, then examples of problems. I'd start looking at hand-held recorders, and even test MiniDisc if you like the sound of it, and try a few things with getting your microphone to make contact with the case or heads or whatever you are recording. Using the same simple equipment may be enough to compare against the established sound profiles for a given problem. Could be pretty cool to have a collection of known problems... as long as it is up to the human ear type thing, you could compress them to MP3 format, as long as you keep the bit rate high, and use a quality machine to do it. It would also make hosting the files easier. If there is no place else to do it, I certainly have both the space and the bandwidth to house such a collection at Version3.net. Let me know what equipment you decide to use Jim... I'd be interested to see what can be heard. Bryan Castles Arlington, TX USA '64 Beetle '70 Bus (Ex-Westy) '73 Square www.version3.net ------------------------------------------------------------------- List info at http://www.vwtype3.org/list or mailto:help@vwtype3.org </x-charset>