Headphone IC

[rekent]

What would be the best IC for volume control and amplification of an audio signal for output to headphones? I wanted an NJM2777 (data sheet attached) but I have been unable to find any of those or a near match replacement. Any suggestions? Would a simple LM386 for each channel be the way to go? Thanks for the input...

 

[keny]

are you stuck with a single polarity power supply?

 

[mneary]

LM386 used to be popular, but there are many better choices today. It doesn't have DC volume control; is that a necessity?

The parametric search at Digikey is very powerful, try it.

 

[rekent]

I have ±12V on the board.

The volume control is a necessity, but I was thinking if I have to end up using an LM386 I can run the output for both the left and right channels into a dual-gang pot and take my stereo headphone out signals from there.

 

[MikeMl]

Go to this**broken link removed** Click on Audio Products and then Headphone Amplifiers

 

[audioguru]

The Japanese IC is made for a cheap little TV so its distortion is pretty bad.
The LM386 is cheap so it has hiss.

 

[rekent]

audioguru -

I found the following picture on the forums from your advice to another poster. Even though it is based around a LM386 would you still recommend it? I will only be driving headphones, no speakers etc.

**broken link removed**

 

[keny]

so are you looking for quality or just plain functional? I found the 386 to be an easy and quick radio shack brand fix. You could try other things if you want to make it sound better, I was practicing using a lm741. Electronics Experiments: Audio Amplifiers

 

[blueroomelectronics]

The Altoids headphone amp is a popular project.
How to Build the CMoy Pocket Amplifier

 

[rekent]

I am probably looking for midrange quality, but I hope to be able to order the needed components today. The use is a front panel mounted headphone with volume control to be attached to a LED VU Meter

 

[keny]

furman HA-6a uses LM1875's: https://www.electro-tech-online.com/custompdfs/2010/04/HA-6AB_manual.pdf

FWIW here are some pix I took of the insides of one that I owned:
**broken link removed**

 

[audioguru]

The Headwise website has simple not good headphone amplifiers and excellent ones.

 

[rekent]

The Headwise website has simple not good headphone amplifiers and excellent ones.

Care to elaborate as to which you consider excellent ones?

 

[audioguru]

Excellent headphones amplifiers use OPA2134 opamps that have distortion of only 0.00008%. They also have very low noise.
Some fools add a DC load resistor so that they operate the output in class-A to reduce (!!) that unmeasurable distortion.
Good headphones like Sennheiser are 600 ohms so are easily driven with this opamp.

 

[rekent]

What would be your suggestion regarding this attached circuit I just drew up?

Edit: Those supplies should be +/- 12V, I grabbed the wrong symbol by mistake.

 

[MrDEB]

definity look at **broken link removed**
they deal mainly with headphones stuff.
LOTS of different amps etc.
Stay away from the LM386. WHY waste your time and money on a crapy amp.

 

[rekent]

definity look at **broken link removed** ...

I checked them out and, between somewhat frustrating website timeouts, found the basis for the circuit I attached to post #15. Does it seem appropriate to those more experienced with headphone circuits?

 

[keny]

should you not decouple / isolate the output?

 

[keny]

kiwame resistor page

maybe you can get these somewhere in us...

 

[audioguru]

should you not decouple / isolate the output?

Not needed.
The OPA2134 has an input offset voltage of typically 0.5mV. The DC gain of the circuit is 11 so the typical output offset voltage will be only 5.5mV which is nothing.
The OP2134 has FET inputs so it does not have input bias currents in the resistors.