Dear All: I'm trying to  simulate an electret microphone. I'm using a 8v DC voltage source connected to an electret mic through a 4.4K resistor.   Is my simulation Ok with the 4.4K resistor in Parallel with the electret, or do I have to put the resistor in series?     Regards...

Can I move the capacitor that is between the opamp negative input and the opamp output to the feedback resistor to calculate the low pass filter cut off frequency? In all schematics I have seen where there is a buffer after an opamp, the low pass filter is formed by a capacitor between the...

I have uploaded the new schematic and the board of the CMD v1.0   CMD: Cmoy Multiloop Desktop.   https://www.dropbox.com/s/tsuml8vn4e9aqdy/CMDV1.png     https://www.dropbox.com/s/z9cjbjtp9n59gw7/CMDV1.rar   Regards. Alfredo Mendiola Loyola Lima, Peru

I have designed a Pimeta V1 mod for desktop use. I don't use a virtual ground. Does Pimeta work with real ground instead of Virtual Ground? How can I attach a picture on this forum? I'm using a 7812 and 7912 regulator to get +/-12v with real ground. Here is the schematic link...

Can I remove the Class A Biasing from the Pimeta V2 schematic? I would like to remove Q2, Q3R, Q3L and the RBias resistor? Is there a problem If a Remove the Class A Biasing from Pimeta V2? Scehamtic: http://tangentsoft.net/audio/pimeta2/misc/sch-2.01.pdf Regards. Alfredo Mendiola Loyola...

I have a lm4880 headphone amplifier and I want to know if a cmoy with an opamp opa2134 will sound better than a lm4880 or a TPA152 chips ?

  It also applies to inverting input Moving the wiper to the mid position and high pass filter?? Full-up, assuming low source impedance: bass cutoff is 0.1uFd against 100K or 15.92Hz. way-down: bass cutoff is again 0.1uFd against 100K or 15.92Hz. At "half loudness": bass cutoff is 0.1uFd...

Could you help me to calculate the cut off frequency with the following schematic:   C2= 0.0000001 F (0.1uF) R2= 22000 (22K) fc= 72.34 Hz at -3dB   If I add a 10 K pot at middle position Do I have to make parallel 5K||5k = 2.5K and add it to 22K to get 24.5K ? C2= 0.0000001 F (0.1uF) R=...

Dear All:   I need to calculate the max power in mw for a Cmoy design using an opa2134 opamp.   The opa2134 datasheet states that the max current by channel is 35mA.   I'm using this formula: P = I^2 * R = ((0.035)^2) * 16  =  0.0196 W = 19.6 mw @ 16 Ohm P = I^2 * R = ((0.035)^2) * 32  =...

Thank you.   You are right I have tested my lm4880 amplifier with a 75 ohm load and with a 10K load and it works well without heat.   The LM4880 sounds very good with my 16 ohms headphone.   Next week i will test a 64 ohm headphone with the lm4880 amplifier.   Regards. Alfredo Mendiola...

Dear All:   Do you know how to detect amplifier oscillations with and oscilloscope ?   I have connected my oscilloscope to an 75 ohm metal file resistor and a 10K metal film ressitors.   The LM4880 output sine wave is Ok. (Input voltage 1.2 vrms)   If the amplifier oscillates does the...

Dear All:   The lm4880 datasheets states that we can use a headphone from 8 Ohms to 32 Ohms.   Do you know If I can use a 64 Ohm headphone with that chip?   Is any risk or problem by using the LM4880 with a load grater than 32 ohms?   Regards. Alfredo Mendiola Loyola Lima, Peru

Dear All: To achieve a gain of 5 Can I use a Rf=5000 ohm and Ri=1000 ohm or Do I have to use Rf=1000 Ohm and Ri=250 Ohm.? I will use the R9 resistor = 1.6K to reduce the DC offset voltage. Schematic: (TPA6120A2 Evaluation Board) Gain = ( 1 + (Rf/ri)) Regards. Alfredo Mendiola Loyola Lima, Peru

Dear All: To achieve a gain of 5 Can I use a Rf=5000 ohm and Ri=1000 ohm or Do I have to use Rf=1000 Ohm and Ri=250 Ohm ? I will use the R9 resistor = 1.6K to reduce the DC offset voltage. Schematic: (Evaluation Board) http://www.ti.com/lit/ug/slou169/slou169.pdf Regards. Alfredo Mendiola...