The Objective2 (O2) Headphone Amp DIY Project

[agdr]

Originally Posted by oslpag

Thanks for the info. I am not too worried about the output plug, that can easily be sorted out. I will get one and see how it goes as it is not so expensive.

Thanks again

Yep, you can always just cut the plug off and put on a 2.1mm if needed.

[agdr]

Originally Posted by Limp

I'm getting 24V across C8 and C9.
Bugger, I guess that means being careful with those MOSFETs just isn't careful enough.

Just curious - which mosfets from those listed on the BOM did you use (which part numbers)?

[timpert]

Some days ago I announced that I would write a step-by-step walkthrough for the construction of the O2. Problem is, I got sick and now I have some catching up to do with other things. Given the lukewarm response to my initial announcement, I am now in doubt if I should continue making the walkthrough or not. If there's sufficient interest in it, I will finish it in a while, if not, I will simply abandon my current effort and move on to other things. Just let me know.

[BuildMeSomething]

Originally Posted by oslpag

I am having a nightmare trying to find a power supplier for the O2 here in the UK. I have found this, would it work for the UK?

Oslpag, I'm using this ac-ac multi-voltage adaptor from Maplin [it's the one listed in the BOM], measures just over 17v unloaded when set to 15vac out.

Paul

[oslpag]

Originally Posted by BuildMeSomething

Oslpag, I'm using this ac-ac multi-voltage adaptor from Maplin [it's the one listed in the BOM], measures just over 17v unloaded when set to 15vac out.

Paul

Thanks Paul, don't know how I missed that one?

[Limp]

Originally Posted by agdr

Just curious - which mosfets from those listed on the BOM did you use (which part numbers)?

FQU17P06 for Pch and the Nch says FQPF10N20C. It's what was supplied with Jokeners kit.
I have now replaced both MOSFETs and all tests seem ok. I get ~250mV on the Low Voltage Shutdown test, but there is still very loud 'pop' when I turn it on.

[lorriman]

Originally Posted by timpert

Some days ago I announced that I would write a step-by-step walkthrough for the construction of the O2. Problem is, I got sick and now I have some catching up to do with other things. Given the lukewarm response to my initial announcement, I am now in doubt if I should continue making the walkthrough or not. If there's sufficient interest in it, I will finish it in a while, if not, I will simply abandon my current effort and move on to other things. Just let me know.

I for one would be delighted by such a guide. I expect there are others but my feeling is that the majority may be lurkers unwilling to post. If you do decide to abandon it, would you instead consider a testing guide? Perhaps as a youtube video.

[lorriman]

Originally Posted by FREDtheDOG

Yes I do it very often, lock the direction of rotation against a solid block, or if I'm making something like this the end panels are small and get too hot to hold

I screw the end panels onto the case and hold the body of the case while I drill works a treat :-)

cheers

Great, thanks for that, Fredthedog. The Front Panel Express software has a print option that seems to work, to help us get the holes correctly positioned; although I had to modify the 'scale' option in the print dialog to 106.90% to get a perfect match.

[agdr]

Originally Posted by Limp

FQU17P06 for Pch and the Nch says FQPF10N20C. It's what was supplied with Jokeners kit.
I have now replaced both MOSFETs and all tests seem ok. I get ~250mV on the Low Voltage Shutdown test, but there is still very loud 'pop' when I turn it on.

Thanks! Just curious about those. No ideas about the turn on pop though, unfortunately.

[lorriman]

Anyone got any ideas on stenciling the markings on to a diy front panel? I'm currently thinking of using a common plastic stencil with a water based pen and then covering it with shellac or laquer. I did think of permanent marker but supposedly the alcohol in the shellac would make it smear. I'm also finding that permanent marker doesn't show up too well. I suspect water-based pen will be just as bad. Perhaps acrylic paint will be necessary.