XEN SHPP -- Simple Headphone Protection

By pure change, I bumped into an old thread at DIYA today about a non-comforming notice from TI.
OPA2604 is dead

The OPA2604 can no longer support +/-24V as per datasheet.
In fact TI has probably taken it off their product line completely.

Therefore, should you wish to build the +/-24V version of the SHPP, the only remaining opamp choice is the ADA4522-2.
Since one practically cannot get the 2604 anyhow, I guess it has not been a real problem.

In any case please take note.


Patrick
 
This is an old thread that needed re-opening.
But a couple of updates is due because of the latest SL HPA GB, though the information is not new.
https://www.diyaudio.com/community/...ear-headphone-amp-pcb-set.399425/post-7388742

As mentioned also in post #29:
https://www.diyaudio.com/community/...adphone-protection.292681/page-2#post-5213493
A R20 has been added to the PCB so as to turn a 24V relay coil into a (for example) 30V equivalent.
With 6V extra to play with, one can also replace R20 with a resistor + a LED.

Fr completeness, I added here a revised schematics with R20 added.
There is nothing new compared to that posted before, except for that.

SHPP 2x15V Sch.png


Also for +/-15V applications, a couple of alternative components can also be considered.

IC1 -- Any JFET input dual opamp in SOIC8 and +/-15V will do, e.g. OPA1642 ir OPA2145
Q1~5 -- I have been using Toshiba 2SC3324/2SA1312, but now replaced by 2SC2713/2SA1163, in BL grade.


Patrick
 
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