AudioFlix Headphones Amp Family

[Ciro82]

I'm proud to present you my headphones amplifiers family:

The 1st one is a Class AB push-pull driven by an OPA2604AP, with a Gain selector:

The 2nd one is a Class A MosFET:

Then i decided to make 2 expansion boards, a DAC one and a Delay (antipop) one:

 

[Julian RO]

Hi,
Have you tested the Class A MosFET variant?

 

[Ciro82]

Hi,
Have you tested the Class A MosFET variant?

Hi, I haven't tested the MosFET one yet.
The class AB one is tested and completed 😃

 

[Ciro82]

This is the Class AB one, tested with a classic transformer (waiting for the PCB mount one)

 

[DontHertzMe]

I'm assuming R14 in the first schematic should be 10 ohm?

 

[Ciro82]

I'm assuming R14 in the first schematic should be 10 ohm?

Oh! Sorry, yes of course it's 10 ohm

 

[DontHertzMe]

I like that the class AB amp can take both through-hole and SMD transistors .

What device are you using for the DAC? PCM2704?

 

[abstract]

What happens if you short out C2 and C4? Seems they might not be needed with a symmetric power supply, unless you also want a high-pass filter.
In my limited experience the "better" op-amps always seem to perform a lot worse in simulations, and the "cheap" NE5532 is really hard to beat.

 

[Ciro82]

I like that the class AB amp can take both through-hole and SMD transistors .

What device are you using for the DAC? PCM2704?

Yeah i think it's a clever idea hahah!
I went for a cheap and easy design using a PCM2902
I'm actually tinkering on a good design using I2S interface and a high quality DAC chip.

 

[Ciro82]

What happens if you short out C2 and C4? Seems they might not be needed with a symmetric power supply, unless you also want a high-pass filter.
In my limited experience the "better" op-amps always seem to perform a lot worse in simulations, and the "cheap" NE5532 is really hard to beat.

C2 and C4 are part of the feedback network, they are needed to keep out the DC Offset. The large values of those capacitor are also meant to keep a low pole freq.

About the OpAmp OPA2604AP i can tell you it's night and day compared to a cheap NE5532...

 

[abstract]

Ok so you only want GND from the other side of the speaker, but won't the polarised cap still have very close to 0V across it? Seems like it will have high DC leakage and variable capacitance.

 

[Ciro82]

Ok so you only want GND from the other side of the speaker, but won't the polarised cap still have very close to 0V across it? Seems like it will have high DC leakage and variable capacitance.

Cordell says it's better to have it (capacitor)


What about this one? My AB power amp:

 

[Ciro82]

Received the incapsulated toroidal tansformer!

 

[Ciro82]

Latest build:

 

[Ciro82]

Next project, XLR and RCA input, anti-pop delay: