Bipolar Power Supply - Necessary?

[mattpocket]

Hi Guys,

I havent been round here for a while, I've been taking a break from building but I am planning an IC based amp to use as a headphone amp.

My friends band use a sampler and his current headphone amp just isnt loud enough for him to hear the metronome whilst playing, so I'm planning on building him a louder one!

http://www.generalguitargadgets.com/pdf/ggg_lm3886_amp.pdf

This is the project I like the sound of, and I think it might be loud enough, but the project says I need to use 18v dc BIPOLAR power supply. What is a bipolar power supply and would a normal 18v dc wallwart do the trick?

Thanks

Matt

[axg20202]

No, a normal 18v supply wont work. Bipolar means it will supply +18V and -18V. There is a simple layout for a bipolar supply at GGG. Just select the correct transformer and voltage regulators for 18V according to the build instructions. You will want to use some heat sinks on the regulators.

...when I built one of these, I extended the GGG layout to add pads for the PCB-mounted transformer I bought (from RS in the UK) and also a fuse holder, so that everything was PCB mounted. Worked a treat. I got the regulator heat sinks from RS too. In fact, if you need a couple of these, I have some spares.

[the_random_hero]

That's going to be a VERY loud headphone amp (to the point of easily causing hearing damage and blowing up headphones at with the volume pot turned down a fair bit). Maybe look at a push-pull Ruby design, here 1w is PLENTY of power for driving headphones.

[axg20202]

Well, yes, I was going to say the same thing but it wasn't the question. You're right though - this is overkill for a headphone amp. Maybe you should be looking at how his on-stage monitoring is being managed in general before building something that'll blow his head off! e.g. what cans is he using - are they closed or semi-open or even, worst of all, on-ear design? Maybe some isolating headphones would be a better option, with a low-level full mix added so that he monitor everything in the cans?

[MartyMart]

Search for the "Headbanger" headphone amp here, it's easy /single supply and LOUD as hell !!!
( but tell that guy to watch his ears ,,, they are NOT replaceable !! )

MM.

[mattpocket]

Thanks for the replies guys, sorry it took so long to reply.

Useful info, as usual! 

[gez]

NE5532 op-amp can drive phones no problem.  They're standard dual op-amps (wire up in the normal way), but can source/sink a fair bit of current. 

Run them from a 12V supply and you'll have all the volume you need.  Cheap, low-noise, audio amps.  My first choice for this sort of thing.