I'm designing something for reproducing the recorded sound of a church bell over a PA system. The bell has a dominant fundamental frequency of 700Hz with all the complex harmonics and resonances of a brass bell.
To reduce extraneous noises, I'm thinking of passing the signal through a simple passive bandpass RC filter - a second-order high-pass and a first order low pass. A tentative design of the filter produces these results: Relative to a broad mid-range centered around ~3.3 kHz, the response is down -1.8dB at 700 Hz, -1.5dB at 15 kHz, and -21dB at 100Hz. Phase is about +50º at 700 Hz and -30º t 15 kHz.
The target audience is a collection of 'ordinary' people, that is, not audio enthusiasts with trained ears. Do you think they will easily notice the difference between the filtered and unfiltered sounds? (It doesn't really matter if they do notice but well, I'd like to have an idea).
To reduce extraneous noises, I'm thinking of passing the signal through a simple passive bandpass RC filter - a second-order high-pass and a first order low pass. A tentative design of the filter produces these results: Relative to a broad mid-range centered around ~3.3 kHz, the response is down -1.8dB at 700 Hz, -1.5dB at 15 kHz, and -21dB at 100Hz. Phase is about +50º at 700 Hz and -30º t 15 kHz.
The target audience is a collection of 'ordinary' people, that is, not audio enthusiasts with trained ears. Do you think they will easily notice the difference between the filtered and unfiltered sounds? (It doesn't really matter if they do notice but well, I'd like to have an idea).
Why do you think you need the filter?
Does the bell sound over extend the "pa system" in some way?
If it does why not simply apply the filter to the recording?
Does the bell sound over extend the "pa system" in some way?
If it does why not simply apply the filter to the recording?
The might if both are played back to back or at the same time, without one of those real time references the only thing they might comment on is how authentic it sounds but even that is unlikely unless they are specifically asked to comment.
Why? Well, as I said before, it's to reduce unwanted noise.
I made a few test recordings of our local church bell with a phone and it was impossible to avoid background noise. People conversing, low frequency engine noise and traffic rumble were particularly objectionable. I found that a quick and dirty editing with software resulted in marked improvement.
Of course, I'm going to make another recording for actual use, with a cardioid mike, careful selection of location and direction, etc. But it won't be with high-end professional equipment as I don't have those. Another big problem is that I can't choose a quiet time. The community is very close-knit and too aware of the church and the bell. Ringing the bell at odd times will create a lot of confusion.
I made a few test recordings of our local church bell with a phone and it was impossible to avoid background noise. People conversing, low frequency engine noise and traffic rumble were particularly objectionable. I found that a quick and dirty editing with software resulted in marked improvement.
Of course, I'm going to make another recording for actual use, with a cardioid mike, careful selection of location and direction, etc. But it won't be with high-end professional equipment as I don't have those. Another big problem is that I can't choose a quiet time. The community is very close-knit and too aware of the church and the bell. Ringing the bell at odd times will create a lot of confusion.
An audio enthusiast with a trained ear might pick up on subtle differences, but the average listener in your target audience is unlikely to notice significant changes between the filtered and unfiltered sound.
Right, you're going to be able to do more to clean it up with software so I don't see why there would be a need to for a harware filter.
I would suggest inexpensive analog crossover with fourth-order high-pass filter at 550 - 600 Hz.
That's exactly the best and cheapest option. Why use a specific hardware for just one thing if it can solved so easily? Apply it to the recording, it will produce the same results. If you have background noises, get closer to the source. Or use something for the directivity. Use a salad bowl, hold the phone or mic with the mic in the middle of the opening pane and you have a instant make shift directional recording device.
Or just download high quality sample of bells.
So you dont have to clean up recording or deal with ambient noise.
It is a fun venture though to record outdoors
in the environment.
Wav editor will help you apply and hear these filters.
simple 6 dB filters at 700 Hz yes have been used to clean
up various instruments. Or often lower to 400 Hz
Depends on bandwidth.
Mainly more for cleaning up high harmonic distorted timbres.
High frequency can often have more step roll off and can be lower
than assumed. Why Wav editors or real time software always fun too
Would like to see the speaker system as well you end up using.
Trying to remember old tube amps / speaker brands that have been dug out of bell
towers for electronic bell systems. Amplifiers that survive the worst of worse
and full of bird stuff from being up in the tower so long. But kept on going
So you dont have to clean up recording or deal with ambient noise.
It is a fun venture though to record outdoors
in the environment.
Wav editor will help you apply and hear these filters.
simple 6 dB filters at 700 Hz yes have been used to clean
up various instruments. Or often lower to 400 Hz
Depends on bandwidth.
Mainly more for cleaning up high harmonic distorted timbres.
High frequency can often have more step roll off and can be lower
than assumed. Why Wav editors or real time software always fun too
Would like to see the speaker system as well you end up using.
Trying to remember old tube amps / speaker brands that have been dug out of bell
towers for electronic bell systems. Amplifiers that survive the worst of worse
and full of bird stuff from being up in the tower so long. But kept on going
The initial strike of the bell will have a wide spectrum, going well below 700Hz I suspect - filtering out the bass may make the sound more tinny for this impact transient. I suspect you'd might do better to noise-gate the recording rather than high-pass filter.