Pro Audio Design Forum

Hello, Had built several of these for myself and family, very happy with the resulting sound. Do have a question though. As I have a brother that would like a little more volume with the headphones he is using, couldn't I just change out the 1246 chip for the 1243 chip and have 3 DB less loss? THAT ...

Hi Wayne, Did try to attach some pictures, but didn't seem to be able to. Don't have a web site to post them on as haven't really needed one for anything else. If there is easy way to attach some pics, let me know and I will do so. Have a good shot of the transistors. If you want to, let me know you...

Hello, Got a little carried away trying to make this amp good enough to keep me happy for a number of years. Sounds very good indeed, limit is my headphones at this point. Used a MR room proof box that had 1/2" thick aluminum walls, good brass with gold plate connectors, alps blue pot for volum...

Hi,

No, exposed metal on the back side. Glad I hesitated and checked before applying power. Should have insulators tomorrow. Thanks for the help.

Regards,
Greg

Hello,

Transistors were from Digikey.com, detail on one of them below. Both were from same company and the collector of all the transistor shows a short to the heat sink.

Regards,
Greg

Manufacturer STMicroelectronics
Manufacturer Part Number BD139-16
Description TRANSISTOR NPN 80V 1.5A SOT32

Hello,

Thanks for the feedback. Did get a chance to check these transistors and they indeed do need insulators. Have some on order and should have the amp working this weekend.

Regards,
Greg

Hello, Was hoping to confirm something before I get to applying power to my new headphone amp. Believe I read somewhere that the BD139 & BD140 transistors used in this project did not need a insulator pad between them and the heat sink. Heat sink is not grounded to the case and I did apply a tou...

Hi Wayne, Thank you for the feedback. Seems likely should be able to drive them loud enough as is. As far as biasing further class A, I have collected heat sinks off old boards and such going in the trash for years and have quite a selection already on hand. Haven't yet had one wear out. ;) Really i...

Hello all, Had been looking for a really good headphone amp to build for some time and believe this is likely it. Would just like to ask if anyone has experience in driving Planar headphones with it. I believe that it should have plenty of drive from what I am reading, but as am going to be buying r...