I'm building a portable small speaker system and I want something to do these things and I've been reading that a capacitor could do it. (but some disagree so I don't know what to do.)
1. Limit the low signals (-6db) below 120 hz going to my L/R speakers.
2. When and if I add my expensive small woofer, then I would like to limit really low signals under 40 hz.
3. I also think getting rid of the lower frequencies will allow me to turn up the volume since the speaker will not being hitting its xmax as much - true?
If a capacitor can do that, what site is best to figure the value?
I'm also thinking that a capacitor to the woofer, if large enough, might provide an extra boost of current during low bass passages? What are the opinions about that?
Thanks
1. Limit the low signals (-6db) below 120 hz going to my L/R speakers.
2. When and if I add my expensive small woofer, then I would like to limit really low signals under 40 hz.
3. I also think getting rid of the lower frequencies will allow me to turn up the volume since the speaker will not being hitting its xmax as much - true?
If a capacitor can do that, what site is best to figure the value?
I'm also thinking that a capacitor to the woofer, if large enough, might provide an extra boost of current during low bass passages? What are the opinions about that?
Thanks
You can make a first order high pass filter with a capacitor and a resistor, the speaker taking the place of the resistor, you want to look for passive crossovers. This is a useful tool mh-audio.nl - Crossover Networks
Thanks that is a good site. I went to it but I'm wondering: Do I enter the ohms of the speaker, the RE, or should I look at the impedance graph of the speaker and see what the ohms are at the HZ that I want to start the slope, ie 120hz?
Do you think you have the time to answer the other questions?
thanks
Do you think you have the time to answer the other questions?
thanks
Based on the spec sheet for the speakers, I see that the ohms of one of the speakers is 60 at the start of the slope for the reduction and the other is at 20 ohms. Do I use those for the ohm's entry?
thanks
thanks
sure thanks
Fountek FE83 3" http://www.parts-express.com/fountek-fe83-3-full-range-driver-8-ohm--299-020 Power Handling (RMS)12 WattsImpedance8 ohmsFrequency Response100 to 25,000 HzSensitivity85.7 dB 1W/1mVoice Coil Diameter0.78"Thiele-Small ParametersResonant Frequency (Fs)122 HzDC Resistance (Re)6.5 ohmsVoice Coil Inductance (Le)0.66 mHMechanical Q (Qms)2.36Electromagnetic Q (Qes)0.88Total Q (Qts)0.64Compliance Equivalent Volume (Vas)0.03 ft.³Mechanical Compliance of Suspension (Cms)0.77 mm/NBL Product (BL)3.6 TmDiaphragm Mass Inc. Airload (Mms)2.2gMoving Mass Of Diaphragm (Mmd)2.1Maximum Linear Excursion (Xmax)3 mmSurface Area of Cone (Sd)28.27 cm² Tang Band W3-2108 3-1/2" RBM
http://www.parts-express.com/tang-band-w3-2108-3-1-2-rbm-micro-subwoofer-4-ohm--264-949Nominal Diameter3-1/2"Power Handling (RMS)25 WattsPower Handling (max)50 WattsImpedance4 ohmsFrequency Response45 to 1,000 HzSensitivity77 dB 1W/1mVoice Coil Diameter1.25"Thiele-Small ParametersResonant Frequency (Fs)45 HzDC Resistance (Re)3.6 ohmsVoice Coil Inductance (Le)0.21 mHMechanical Q (Qms)4.67Electromagnetic Q (Qes)0.51Total Q (Qts)0.46Compliance Equivalent Volume (Vas)0.06 ft.³BL Product (BL)6.17 TmMoving Mass Of Diaphragm (Mmd)17.96Maximum Linear Excursion (Xmax)7 mm
thanks
Fountek FE83 3" http://www.parts-express.com/fountek-fe83-3-full-range-driver-8-ohm--299-020 Power Handling (RMS)12 WattsImpedance8 ohmsFrequency Response100 to 25,000 HzSensitivity85.7 dB 1W/1mVoice Coil Diameter0.78"Thiele-Small ParametersResonant Frequency (Fs)122 HzDC Resistance (Re)6.5 ohmsVoice Coil Inductance (Le)0.66 mHMechanical Q (Qms)2.36Electromagnetic Q (Qes)0.88Total Q (Qts)0.64Compliance Equivalent Volume (Vas)0.03 ft.³Mechanical Compliance of Suspension (Cms)0.77 mm/NBL Product (BL)3.6 TmDiaphragm Mass Inc. Airload (Mms)2.2gMoving Mass Of Diaphragm (Mmd)2.1Maximum Linear Excursion (Xmax)3 mmSurface Area of Cone (Sd)28.27 cm² Tang Band W3-2108 3-1/2" RBM
http://www.parts-express.com/tang-band-w3-2108-3-1-2-rbm-micro-subwoofer-4-ohm--264-949Nominal Diameter3-1/2"Power Handling (RMS)25 WattsPower Handling (max)50 WattsImpedance4 ohmsFrequency Response45 to 1,000 HzSensitivity77 dB 1W/1mVoice Coil Diameter1.25"Thiele-Small ParametersResonant Frequency (Fs)45 HzDC Resistance (Re)3.6 ohmsVoice Coil Inductance (Le)0.21 mHMechanical Q (Qms)4.67Electromagnetic Q (Qes)0.51Total Q (Qts)0.46Compliance Equivalent Volume (Vas)0.06 ft.³BL Product (BL)6.17 TmMoving Mass Of Diaphragm (Mmd)17.96Maximum Linear Excursion (Xmax)7 mm
thanks
That's ok, they are free air measurements, they change when the drivers are in a box. The nominal impedance is generally used when calculating a simple crossover, so 8ohms and 4ohms respectively
Online crossover calculators are essentially worthless, taking no account for impedance as it varies with frequency & thereby affects the behaviour.
A 1st order electrical high pass will roll the driver off (assuming a constant impedance, which isn't the case) at 6dB/octave & is -3dB down at the nominal target frequency. Not very much protection, but some. You'd need one for each channel of course. Eliminating <40Hz signals really needs an active filter; technically it's possible to do it passively, but the complexity, insertion losses etc. involved make it impractical.
A 1st order electrical high pass will roll the driver off (assuming a constant impedance, which isn't the case) at 6dB/octave & is -3dB down at the nominal target frequency. Not very much protection, but some. You'd need one for each channel of course. Eliminating <40Hz signals really needs an active filter; technically it's possible to do it passively, but the complexity, insertion losses etc. involved make it impractical.
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