The bass will indeed roll off at very low frequencies but I doubt you would notice it. The compromise is between good low frequency response and the settling time when something is plugged in. It takes time for the capacitors to charge if there is any DC superimposed on the input signal and the bigger the value the longer it will take. The DC stabilization isn't from the input signal, it is from the output stage. Consider that with symetrical supplies the output point should ideally be at zero volts when no signal is present. With that design, any differences in components, including transistor gain, may cause differences between the top half of the output stage and the bottom half and that would result in a DC 'offset' being permanently present across the headphone coil. Good practice is to use negative feedback from the output point back the the input so any offset is cancelled out.For DC coupling (in case there are too much mA at the input of the amp), I use two 1uF MKP cap´s. The original value are 1,5uF parallelled with 0,022uF cap´s- so there may be a very small amount of low level bass reduced, buth I don´t think it´s noticeable. Is that what you refer to DC stabilization?
TLE2426 can only supply or sink 20mA maximum, that is far too small for an amplifier of that type, especially if you are driving low impedance (< 32 Ohms) headphones. If the TLE2426 can't cope you will get serious distortion and cross talk between the channels. 170uA battery drain can be ignored it is so small (0.00017 Amps).Also, I´m using a TLE2426 from Texas Instr. paired with a MKP 1uF cap. to create a virtual signal ground, and NOT using the negative voltage from the battery for ground. The datasheet say´s the Supply current for the TLE2426 are 170 micro Ampere. Is this what this component part will consume/drain?
This has nothing to do with the sound quality, it is to reduce the chances of instability. Ideally, the supply pins to the DAC have only steady DC on them but in real life, there will always be some resistance and inductance in the supply and wiring (including copper PCB traces) which produces a drop due to the current flowing through them. The capacitors close to the supply pins work like a local power reserve, they charge from the supply line but being very close to the IC they can release charge if necessary at the point it is needed. The reason for using two capacitors is that high values are inevitably electrolytic types, good for holding a large reserve but not so good at releasing it quickly. Small capacitors have small reserve but can release it almost instantly. By using them in parallel you get the best of both characteristics. Technically, electrolytics tend to increase their impedance as the frequency increases and small values, which are usually ceramic do the opposite. You should use a ceramic capacitor and 100nF (=0.1uF) is a good choice but the type is more important than actual value.Also, when I use the discrete OpAmp´s in my AK4399 DAC, the manufacturer recommend me to parallell the 240uF original electrolytic cap´s with a small bipolar/unpolarized plastic cap to each power pin to nearby ground.
You should keep C309 and C310 as they are but remove everything before them.
TLE2426 can only supply or sink 20mA maximum, that is far too small for an amplifier of that type, especially if you are driving low impedance (< 32 Ohms) headphones. If the TLE2426 can't cope you will get serious distortion and cross talk between the channels. 170uA battery drain can be ignored it is so small (0.00017 Amps).
Brian.
You should keep C309 and C310 as they are but remove everything before them.
The bass will indeed roll off at very low frequencies but I doubt you would notice it. The compromise is between good low frequency response and the settling time when something is plugged in. It takes time for the capacitors to charge if there is any DC superimposed on the input signal and the bigger the value the longer it will take. The DC stabilization isn't from the input signal, it is from the output stage. Consider that with symetrical supplies the output point should ideally be at zero volts when no signal is present. With that design, any differences in components, including transistor gain, may cause differences between the top half of the output stage and the bottom half and that would result in a DC 'offset' being permanently present across the headphone coil. Good practice is to use negative feedback from the output point back the the input so any offset is cancelled out.
Brian.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?