Hi all,
I am going to build the circuit as the image. I would like to know is the LF HF filter really necessary? Will they affect the harmonic or the character of the sound?
Cheers!
I am going to build the circuit as the image. I would like to know is the LF HF filter really necessary? Will they affect the harmonic or the character of the sound?
Cheers!
I can't see the picture, but usually HF filter is at the input of the amplifier, to eliminate ultrasonic trash.
The software is LTSpice, its free: Linear Technology - Design Simulation and Device Models
I do not suggest anything. The 2k are good if overvoltage protection is needed. If the utmost performance is needed i would replace the 2k with 100 ohm.
Also replace the 82k with 47k and the 100k with 1MEG to minimize DC offset.
I do not suggest anything. The 2k are good if overvoltage protection is needed. If the utmost performance is needed i would replace the 2k with 100 ohm.
Also replace the 82k with 47k and the 100k with 1MEG to minimize DC offset.
The 2k/220p combo also keeps RF out. UK designers tend to be more considerate in that regard because arguably longwave broadcasting still finds the most use there.
With a FET input opamp like the OPA2134 suggested, DC offset should be pretty much a non-issue. 1Meg/47k would be better for a bipolar though, in which case it may reduce clicking upon volume change.
Making up for a whopping 0.37 dB loss in the input filter with gain in the buffer strikes me as a bit silly though, unless you're keen on comparing the listen-source output to the source directly in listening tests. Otherwise I'd just leave out the 6k2, swap the 270R for a 2k (for reduced impedance imbalance) and call it a day.
Speaking of silly, the exact value of the 82k is not remotely critical, so you may just as well use another 100k there instead. One less type of resistor to order / look for.
The headphone amplifier has about 6 dB more gain than I'd consider necessary here, but not sure about stability implications if changed.
With a FET input opamp like the OPA2134 suggested, DC offset should be pretty much a non-issue. 1Meg/47k would be better for a bipolar though, in which case it may reduce clicking upon volume change.
Making up for a whopping 0.37 dB loss in the input filter with gain in the buffer strikes me as a bit silly though, unless you're keen on comparing the listen-source output to the source directly in listening tests. Otherwise I'd just leave out the 6k2, swap the 270R for a 2k (for reduced impedance imbalance) and call it a day.
Speaking of silly, the exact value of the 82k is not remotely critical, so you may just as well use another 100k there instead. One less type of resistor to order / look for.
The headphone amplifier has about 6 dB more gain than I'd consider necessary here, but not sure about stability implications if changed.
I would like to know is the swap of the 270R to 2K for the OPA2134? If I am going to using the LME49860?
I want to increase the output gain to 9dB. But I cruise that will get the noticeable noise.
I would like to know if I change the filter of the output stage to rise the cutoff of the HF. Replace the 2.4K to 1K... will the value of the db lose change? Cheers!
Is the output resistor really necessary? Cheers!