Members IsildursBane Posted February 5, 2011 Members Share Posted February 5, 2011 This sounds kind of silly, but I have a sound design project where I'd like to multi-sample an electric can opener by recording it operating at different speeds. The thing is - I know that some motors you can control by varying the voltage and others you can control by varying the frequency, but I don't know which is which and I don't know which is found in a can opener. I have access to a Variac, so controlling the voltage ought to be fairly easy, but controlling the frequency is going to be more of a challenge - enough so that I'd probably abandon this idea altogether. According to google, it looks like kitchen blenders are controlled off voltage, so the Variac should work, should it not? FWIW, I only need the can opener to survive long enough to get the recording - I don't care if it eventually burns up. Link to comment Share on other sites More sharing options...
Members Redbassman86 Posted February 5, 2011 Members Share Posted February 5, 2011 Voltage it is! Hz is controlled with a VFD or Variable Frequency Drive, and are used on mostly 3 phase motors. Link to comment Share on other sites More sharing options...
Members Bim1959 Posted February 5, 2011 Members Share Posted February 5, 2011 Why not use a keyboard (if you have one) that can sample sounds and use it to record the can opener at normal speed. The keyboard should naturally change the speed and tone of the can opener depending what notes you play and you wont have to risk burning it up in the process. Link to comment Share on other sites More sharing options...
Members IsildursBane Posted February 5, 2011 Author Members Share Posted February 5, 2011 Why not use a keyboard (if you have one) that can sample sounds and use it to record the can opener at normal speed. The keyboard should naturally change the speed and tone of the can opener depending what notes you play and you wont have to risk burning it up in the process. I wouldn't even need to do that; the software I'm plugging the recording into can pitch shift in real-time based on parameters fed to it. The problem is that it doesn't sound the same as having samples at multiple speeds (particularly at the extreme upper and lower end of the range). That's why sample libraries record each note of an instrument instead of recording one note and pitch shifting it up and down and it's why guys working on racing games record car engines at different rpm's (the can opener will be part of an engine/vehicle sound). There will still be some pitch shifting, but it will be to transition between the different recordings, not to allow one recording cover the entire range of speeds. Link to comment Share on other sites More sharing options...
Members Coaster Posted February 5, 2011 Members Share Posted February 5, 2011 Why not use a keyboard (if you have one) that can sample sounds and use it to record the can opener at normal speed. The keyboard should naturally change the speed and tone of the can opener depending what notes you play and you wont have to risk burning it up in the process. the opener will struggle at reduced speed and therefore radically change the sound in unpredictable ways. the sampler/altering playback rate will cause formant shift. i've had great success recording odd mechanical sounds with an old SM76. i actually wish mine had not been destroyed in the great flood of 2000, i miss that mic. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 5, 2011 Members Share Posted February 5, 2011 IIRC, most can openers are controlled by a shaded pole motor, which are a synchronous type motor. This means that it will try to operate syncronized to the line frequency and will slip a little under load BUT when you slow it down with slipping (meaning that the rotating field is no longer syncronized with the static field (which rotates electrically rather than mechanically) the torque really drops off like a rock and the motor will tend to stall. Generally, unless you are using the effects of reduced torque to slow the speed with lower voltage (really poor performance) then you will be better off with a variable frequency drive. The challenge here is that most shaded pole motors want o run within a pretty nerrow range of frequencies and thus speeds. It's not the ideal motor for (simple) variable speed control. FWWIW, blenders typically use a universal motor which has a much flatter voltage/torque curve and does not rely on syncronous operation. They all have brushes and will operate on DC or AC. It's been 35 years since I studied motors so the 'ol brain's a bit rusty. Most motors I deal with today are multi-phase induction motors which are a form of syncronous motor with a flat slip/torque curve. Link to comment Share on other sites More sharing options...
Members IsildursBane Posted February 6, 2011 Author Members Share Posted February 6, 2011 Hmmm... Maybe I'll try this with a blender, too. The can opener has a nice clacky sound that I like, but I may be able to get that out of the blender if I slow it down enough. Thanks! -Dan. Link to comment Share on other sites More sharing options...
Members RoadRanger Posted February 6, 2011 Members Share Posted February 6, 2011 A bridged RMX2450 is about 100V - that with one of the signal generator programs loaded on your PC might do the job? I'll assume the can opener is "expendable" and the RMX under warranty . Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 6, 2011 Members Share Posted February 6, 2011 A bridged RMX2450 is about 100V - that with one of the signal generator programs loaded on your PC might do the job? I'll assume the can opener is "expendable" and the RMX under warranty . I was involved with something like this at NAMM about 15 years ago, a power amp variable speed blender serving mixed drinks in the back. A little incident about not having a liquer license or seller's permit ended this demo pronto. Most blenders will operate off of a phase control dimmer just fine. Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted February 7, 2011 Members Share Posted February 7, 2011 Hmmm... Maybe I'll try this with a blender, too. The can opener has a nice clacky sound that I like, but I may be able to get that out of the blender if I slow it down enough. Thanks!-Dan. I'll suggest that a hay elevator may have a similar clacky sound: Maybe you could load the audiotrack from the above link into some computer sound program and varie the speed? Oh, and here's a video that includes the soundtrack of a 50hp 3ph motor spooling up: Maybe you could mix the two soundtracks to get the desired result? Link to comment Share on other sites More sharing options...
Members RoadRanger Posted February 7, 2011 Members Share Posted February 7, 2011 I was involved with something like this at NAMM about 15 years ago, a power amp variable speed blender serving mixed drinks in the back.The latest in party blenders: http://www.blenderblaster.com/blenderblaster Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 7, 2011 Members Share Posted February 7, 2011 The latest in party blenders: http://www.blenderblaster.com/blenderblaster What a cool toy for the BBQ pit Link to comment Share on other sites More sharing options...
Members IsildursBane Posted February 7, 2011 Author Members Share Posted February 7, 2011 I'll suggest that a hay elevator may have a similar clacky sound:http://www.youtube.com/watch?v=26TdxHlav9g&feature=related Ooh... Good call. And my father has one of those. But I have to drive to NY... Maybe you could load the audiotrack from the above link into some computer sound program and varie the speed? This is going to be pitched/slowed down a couple octaves and plugged into a video game as part of a vehicle engine sound where the pitch/speed of the recording will be modulated up & down in real time with the speed of the vehicle engine. I'm trying to limit amount of pitch shifting being done by the game engine, because the aforementioned formant shifting is really obvious and sounds like poo, particularly when you're trying to get it to sound either really fast or (especially) really slow. If I can sample the motor at different speeds, then I can reduce the amount of pitch shifting that the game engine has to apply. -Dan. Link to comment Share on other sites More sharing options...
Members Coaster Posted February 7, 2011 Members Share Posted February 7, 2011 do they really say macintosh? really? or do they say Mcintosh? Link to comment Share on other sites More sharing options...
Members IsildursBane Posted February 7, 2011 Author Members Share Posted February 7, 2011 do they really say macintosh? really?or do they say Mcintosh? Yeah, I knew I'd do that. :-b Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted February 7, 2011 CMS Author Share Posted February 7, 2011 do they really say macintosh? really?or do they say Mcintosh? Or do they say McIntosh ? Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.