Simply direct coupled class a headphone amp

[syr]

Hi everybody, it's about this one scheme - radically simple and worked.I build a prototype (with major changes in the power supply,and minor changes in the scheme)and have questions :

- what do exactly the connection between R2 and R3 - it works when R2 is directly grounded (i already tested it)?

- better transistors replacement , i mean BD135/BD136 (respectively BD139/140)?

Thanks in advance !

 

[Mooly]

Having R2 returned to the top of R3 increases the input impedance a little (bootstrapping) because R3 will have a similar AC voltage present as compared to the input.

The amp should work with either connection method.

 

[Ken Newton]

I don't see the direct coupling here. C1 and C5 show this circuit as being A.C. coupled.

 

[Mooly]

^ This is true.

 

[rjm]

1. Anything advertised as "ultimate" probably isn't.
2. When a circuit with both AC input and output coupling is introduced as direct-coupled, the best course of action is "eject".

 

[syr]

1. Anything advertised as "ultimate" probably isn't.
.

If course not. It is just "good old classic".

2. When a circuit with both AC input and output coupling is introduced as direct-coupled, the best course of action is "eject".
.

Sorry about that, the introduction isn't mine .
O ja. I have already ejected ... all op amp's . What about all caps "inside the op amp's" - you can't remove them.
Believe me, i already tested "cmoy" circuit, rod elliott headphone amp - Headphone Amplifier ,
another circuit similar like yours, with "diamond output buffer" - http://blog.audioworkshop.org/diamond-buffer-headphone-amplifier/ , and few more circuits with op - amp's . They are pretty good , with ultra low THD, precise, detailed etc... But, after one hour listening, i feel myself tired and i want to put down my headphones. That's not happening with this simple circuit. That's way, i recommend - try it .