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Software Spectrum Analyser
"David Looser" wrote in
message I'm not trying to design speakers, I'm trying to set up align "B-chain" response in an auditorium. I've used RMAA to set the house speaker equalization, and it works. When you are setting over-all response in a large room, remember that you *don't* want flat response, you want a smooth curve for which there is no exact mathematical justification for. Check the Dolby site for "X-curve" for more info about that. http://www.dolby.com/uploadedFiles/z...%20Journal.pdf |
Software Spectrum Analyser
"Arny Krueger" wrote in message
... "David Looser" wrote in message I'm not trying to design speakers, I'm trying to set up align "B-chain" response in an auditorium. First thing to remember in auditorium sound is that you *don't* want flat response. Yup I know. There is a specified curve. What's a "B-chain"? I feel stupid asking this question, but google sheds no light. The "B-chain" is the part of the sound reproduction system that starts at the input selector switch. It includes tone controls/graphic equaliser, power amps, speakers and, of course, room accoustics. Also, if there's a B-chain, then there is an A-chain. Wazzat? That's the part of the sound reproduction sysyem that ends where the B-chain starts. So it's the replay transducer, pre-amps etc. These terms were invented in the 1970s by people who wanted to improve cinema sound. By dividing up the sound system like that it was posssible to produce standards for each part seperately, opening the door to new types of soundtrack, such as Dolby encoded optical. Dolby were major players in this process. Is there a C-chain? Not as far as I know David. |
Software Spectrum Analyser
"Don Pearce" wrote in message
news:49d47b4a.473783703@localhost... Noise and an FFT are very good for finding specific room problems, though, particularly of the moding kind. I guess for this job you need a real time moving FFT that will sit and give you a display of what is happening right now - not a still snapshot of what happened a while ago. Exactly Don't know if Rightmark does that, Having looked at it I don't think it does. I quite like this http://www.qweas.com/download/audio_...cillometer.htm I don't think that does either, and it's quite pricey at $399 David. |
Software Spectrum Analyser
"David Looser" wrote in
message "Don Pearce" wrote in message news:49d47b4a.473783703@localhost... Noise and an FFT are very good for finding specific room problems, though, particularly of the moding kind. I guess for this job you need a real time moving FFT that will sit and give you a display of what is happening right now - not a still snapshot of what happened a while ago. Exactly Don't know if Rightmark does that, Having looked at it I don't think it does. The feature is kinda sorta hidden. Go to "Test Options" and enable the "Acoustics Testing Mode." |
Software Spectrum Analyser
"David Looser" wrote in
message "Arny Krueger" wrote in message ... "David Looser" wrote in message I'm not trying to design speakers, I'm trying to set up align "B-chain" response in an auditorium. First thing to remember in auditorium sound is that you *don't* want flat response. Yup I know. There is a specified curve. What's a "B-chain"? I feel stupid asking this question, but google sheds no light. The "B-chain" is the part of the sound reproduction system that starts at the input selector switch. It includes tone controls/graphic equaliser, power amps, speakers and, of course, room accoustics. Also, if there's a B-chain, then there is an A-chain. Wazzat? That's the part of the sound reproduction sysyem that ends where the B-chain starts. So it's the replay transducer, pre-amps etc. A chain = record B-chain = playback ???? |
Software Spectrum Analyser
"Arny Krueger" wrote in message
... A chain = record B-chain = playback ???? No, all playback. Imagine a typical "HiFi" system with a tuner, an analogue record player and a CD player. The B-chain is the bit that is common to all, ie. tone controls, power amps, speakers and room. There is a separate A chain for each source though. For the record player that would be the turntable, arm, cartridge and RIAA pre-amplifier. The point is that the B chain only needs to be aligned once, by injecting pink noise into a "flat" input of the amplifier and measuring the output with a measurement microphone and spectrum analyser. That is then correct for all sources. Checking for correct frequency response from the record player, or the tuner or CD player can simply be done electrically at the output of each respective A chain, the measurement mic and spectrum analyser can be left in their cases. All this may seem obvious, but before that time film sound frequency response was only specified end-to-end, so it would be perfectly in order to correct for accoustic problems by tweaking the frequency response of the pre-amp. But then what happens if a new audio source is introduced?, that would also need to be "fixed" to provide a correction for that accoustic problem. David. |
Software Spectrum Analyser
David Looser wrote:
"Arny Krueger" wrote in message ... A chain = record B-chain = playback ???? No, all playback. Imagine a typical "HiFi" system with a tuner, an analogue record player and a CD player. The B-chain is the bit that is common to all, ie. tone controls, power amps, speakers and room. There is a separate A chain for each source though. For the record player that would be the turntable, arm, cartridge and RIAA pre-amplifier. The point is that the B chain only needs to be aligned once, by injecting pink noise into a "flat" input of the amplifier and measuring the output with a measurement microphone and spectrum analyser. That is then correct for all sources. Checking for correct frequency response from the record player, or the tuner or CD player can simply be done electrically at the output of each respective A chain, the measurement mic and spectrum analyser can be left in their cases. So would you use white or pink noise, or would it be better to use a well-known piece of music, perhaps by Duke Ellington, to check the A chain? -- Eiron. |
Software Spectrum Analyser
"David Looser" wrote in
message "Arny Krueger" wrote in message ... A chain = record B-chain = playback ???? No, all playback. Imagine a typical "HiFi" system with a tuner, an analogue record player and a CD player. The B-chain is the bit that is common to all, ie. tone controls, power amps, speakers and room. There is a separate A chain for each source though. For the record player that would be the turntable, arm, cartridge and RIAA pre-amplifier. OK, that makes sense. The point is that the B chain only needs to be aligned once, by injecting pink noise into a "flat" input of the amplifier and measuring the output with a measurement microphone and spectrum analyser. That is then correct for all sources. Checking for correct frequency response from the record player, or the tuner or CD player can simply be done electrically at the output of each respective A chain, the measurement mic and spectrum analyser can be left in their cases. Right. All this may seem obvious, but before that time film sound frequency response was only specified end-to-end, so it would be perfectly in order to correct for accoustic problems by tweaking the frequency response of the pre-amp. But then what happens if a new audio source is introduced?, that would also need to be "fixed" to provide a correction for that accoustic problem. Go it. |
Software Spectrum Analyser
"Eiron" wrote in message
So would you use white or pink noise, or would it be better to use a well-known piece of music, perhaps by Duke Ellington, to check the A chain? With modern technology, any source that is has significant content over the desired frequency range can be used to calibrate a chain of components. If you are working with acoustics, it might help if your test source is not steady-state tones. |
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