Trying to design a series notch filter using online calculators for a Dynavox LY401F. I'm getting really high capacitor values. Am I reading it wrong or are those values correct.
Mahalo,
Series Notch Filter
Re = 4.3 Ohms
fs = 53 Hz
Qes = 0.29
Qms = 3.34
Parts List
Capacitor
C = 2408.8 uF
Inductor
L = 3.75 mH
Resistor
Rc = 4.6733532934
Mahalo,
Series Notch Filter
Re = 4.3 Ohms
fs = 53 Hz
Qes = 0.29
Qms = 3.34
Parts List
Capacitor
C = 2408.8 uF
Inductor
L = 3.75 mH
Resistor
Rc = 4.6733532934
What are you trying to do with this notchfilter? I don't see no need for a notch filter on this driver, only a LR filter maybe for the very top frequency, but that peak is up so high, that it probally not needed.
And online calculators are not accurate in general. You need the response of the driver to calculate notch filters, not some theoretical response like used in those online calculators.
And online calculators are not accurate in general. You need the response of the driver to calculate notch filters, not some theoretical response like used in those online calculators.
I get a flat response from 110 to 65k. I was looking into parallel notch filters to cover this range. I was playing around with calculators to get a few different answers to buy components to have a few to test. The series was just so different I was curious why.
The components of the notch filter in original post are intended to flatten the impedance peak of the driver at its 53 Hz resonance frequency. The C and L values are large mainly because of that low frequency.
Leach described how to calculate a full matching network. The three main components R3, L1, and C3 correspond to the values found in many (most?) calculators.
https://leachlegacy.ece.gatech.edu/ece4445/downloads/zobel.pdf
RLC notch filters are typically not employed at a woofer or fullrange driver's resonance frequency, although they can be. Cost of the large components at lower frequencies is often the reason why not.
Leach described how to calculate a full matching network. The three main components R3, L1, and C3 correspond to the values found in many (most?) calculators.
https://leachlegacy.ece.gatech.edu/ece4445/downloads/zobel.pdf
RLC notch filters are typically not employed at a woofer or fullrange driver's resonance frequency, although they can be. Cost of the large components at lower frequencies is often the reason why not.
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Not sure what you are asking for either.
The term "notch" implies a narrow band. (80 - 5k is a fairly broad range)
Do you have some kind of simulation or measurement that shows the "flat response" that you are interested in?
The term "notch" implies a narrow band. (80 - 5k is a fairly broad range)
Do you have some kind of simulation or measurement that shows the "flat response" that you are interested in?
Thanks for the response Dave.
Im trying to lower the db between 80-60k. Notch filters are the only filter im kinda familiar with.
17_Nov_2020_11_17_11.png - Google Drive
Im trying to lower the db between 80-60k. Notch filters are the only filter im kinda familiar with.
17_Nov_2020_11_17_11.png - Google Drive
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What do these curves represent?
Are there different circuits associated with the top (yellow) curve, and the bottom (white) curve?
Are you intending on attenuating the bottom (white) curve so that it is flat between 80 Hz and 5 kHz, and leave a hump below 80 Hz?
😕
Are there different circuits associated with the top (yellow) curve, and the bottom (white) curve?
Are you intending on attenuating the bottom (white) curve so that it is flat between 80 Hz and 5 kHz, and leave a hump below 80 Hz?
😕
Only the yellow curve. White is just noise. I'm trying to pull a little more from under 100hz and over 55khz. Speaker sound good when loud, but at low volume its lacking top and bottom
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I don't think a notch filter will accomplish that. Some other kind of electrical filter attenuation over that broad region isn't really an effective way to get there.
You might be able to use a dsp to actively boost those regions. But you'll be asking a lot of the driver and it may expire prematurely if driven hard.
Otherwise,
A small (1/2" or 3/8" e.g.) tweeter could be added to get more highs above 5000 or 6000 Hz.
If the measurements you have are for free air or infinite baffle, you would likely need to add a woofer to augment below 80 or 100 Hz. If the measurements are with the driver in an enclosure, then a vent or PR could be implemented to extend the bass down somewhat.
The response looks really good for a single driver.
You might be able to use a dsp to actively boost those regions. But you'll be asking a lot of the driver and it may expire prematurely if driven hard.
Otherwise,
A small (1/2" or 3/8" e.g.) tweeter could be added to get more highs above 5000 or 6000 Hz.
If the measurements you have are for free air or infinite baffle, you would likely need to add a woofer to augment below 80 or 100 Hz. If the measurements are with the driver in an enclosure, then a vent or PR could be implemented to extend the bass down somewhat.
The response looks really good for a single driver.
A notch filter is used to notch out a narrow band, hence the name 'notch'.
I think what you need is a simple attenuator, because you want to lower the whole audio band, sort of.
Jan
What you have just described is what some older stereos had a "loudness button" for. It boosts the frequencies that often seem lacking at low listening levels. Loudness compensation - Wikipedia
This would be better done actively, as it is only something you want to compensate for when listening at low levels. If you do it passively (and don't have a way to defeat it) it will make your speakers sound wrong when listening at higher levels.
Tony.
Unless you have a volume potmeter with a loudness tap. In that case, the correction is automagically coupled to level.
Jan
Jan