The input cutoff and output cutoff add and produce -3dB at about 150hz and -3dB at about 80Hz. If you want a -3dB total cutoff at 50Hz then both RC cutoffs must be 25Hz.I'm not quite understanding what needs to be calculated here. In your sketch where theres 30Hz cut-off freqency on the Preamps input. Does that freqency need to be lower than 30Hz or does this freqency stay at 30Hz but adds to the capacitor on the output of the Preamp capacitor which feeds the input cut-off freqency on the Power amp and the headphone amp cut-off freqency to total to 50Hzs as you suggested...
the feedback capacitor is too big at 22uF so it has no effect on the total cutoff frequency. Even if it is 10uF then its cutoff frequency is so low (7.3Hz) that it also will not affect the total cutoff frequency.What about the feedback cut-off freqency. How does this frequency play into the Preamps output capacitor?
If you make the input capacitor, output capacitor and feedback capacitor all with a cutoff (-3dB) at 30Hz then the total cutoff will be -9dB at 30Hz and 30Hz will be at a fairly low level. If you make then all have a cutoff at 16Hz then the total cutoff will be -3dB at 50Hz that you want.Does the feedback capacitor need to change? If I change the 22uf to 2.2uf which will give a cut-off freqency of 32.88Hz on this feedback circuit instead of 3.3Hz. Dose this freqency change an adds to the 30Hz thats on the input of the Preamp. I'm Totally confused on this. Help!
No.Ok.. Radio has a cut-off freqency of 50Hz. Will 50Hz have good decent bass freqencies with that speaker that you posted in post#31?
I told you about the capacitors and I explained why but you don't understand so forget about it.Does the 30Hz at the input of the Preamp stay at 30Hz? Or do i need to change it? YES or NO, if yes then at what cut-off freqency dose it need to be... Please Advise.
For the feedback cut-off freqency dose the capacitor stay at 22uf or do i use the 10uf that you mentioned in Post #81 this will have a freqency of 7.23Hz?
The output capacitor on the preamp will then feed the cut-off freqency for the input of the power amp and for the input for the headphone amp So I would just take the load for each RC input and calculate there cut-off freqency for the Preamps output capacitor.
Coupling capacitors are never two capacitors in series. Use only one coupling capacitor. Calculate its frequency so it passes touch-tones well.Also the Preamp output will also feed the input of the DECODER. I would just use the Preamps output capacitor to calculate for the cut-off freqency for the decoder circuiit? Is this correct! Do I need to remove the 0.1uf capacitor on the input of the decoder. Advise>
You cannot connect the two volume controls in series. They must be connected in parallel. Then the cutoff frequency with a 0.33uF capacitor and two 10k pots is 97Hz.If i use the same 0.33uf coupling capacitor and calculate this with two 10k pots connected in series total would be 20K on the headphones amp input for its cut off freqency at 24.11Hz.
No.Im getting confused again here. You say add up all coupling capacitors together. Isn't the one coupling capacitor 0.33uF on the output of the Preamp feeds the inputs for the Headphone amp and the Power amp for the Speaker?
Each headphones amp has an input capacitor and an output capacitor. Since most of your sound sources are mono then they are parallel.But on the headphone amp there two inputs Left and right for the headphones. how many coupling capacitors are there if both feed off the output of the Preamps output. Im not understanding this.
It is extremely simple...... I don't understand.
You should always have part numbers for ICs on your schematics. I don't know which decoder IC you have and I don't know the value of its input resistors.Enclosed Amplifiers. Please edit the schematic so i can understand what capacitors to add and what capacitors need to be calculated on both amplifiers for a total of 50Hz or less.
The output coupling capacitor of the preamp connects to the decoder and to both volume controls of the headphones amplifiers. I don't know which decoder you are using so I don't know if it needs an additional input capacitor.1.When the Preamps output is connected to the headphones left and right inputs on the amp does the Preamps output (0.33uf 0r 0.56uf which ever one is used) coupling capacitor get connected to the headphones left and right inputs too?
No.Or are the two 100uf capacitors on the headphones amp are those the input coupling caps for the headphones amp?
Yes but I don't know the impedance of your headphones so I don't know if the 470uf capacitors produce a 50Hz cutoff.and the two 470uf caps are the headphones output coupling capacitors?
Bad english.2. When the Preamp output is connected to the bridge amp with speaker and switch over with a on-on switch the preamps output coupling capacitor 0.33 or the 0.56 is connected to the bridge amps input because as you stated there is no input coupling capacitor for the bridge amps input.
No. The 10uF capacitor is the feedback capacitor and the 0.1uF capacitors stop the IC from oscillating.And are the 10uf or are 0.1 caps on the bridge amps output the coupling caps?
I don't know if your radio has an output coupling capacitor so you should add one or two. Is your radio mono or stereo?3. Now when I insert a stereo Plug into the output ear jack on a portable FM/AM radio then the other plug connects to a audio jack on my device then gets connect to the Headphone amplifier input when the Headphones amp switches over to the radio output will my audio jack need a coupling cap for DC voltage coming from the radio output or will the radios output suorce already have this coupling capacitor or the headphone amp on its input and output block for DC voltage. If this make any sense.
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