Capacitor questions

[Boscoe]

Thats awsome thanks for the advice Boscoe :) Do you think I can convert this to SMD ? As your the first real sound expert I've talked to. I've spent months trying to learn this stuff but i'm just scratching the surface, what i really need is a good CMoy design that I can use SMD parts on so I can get it small enough and cheap enough to shoehorn into a tabbaco tin with 2 x 9v batteries. Any ideas ? :) I wont lie, I intend to sell them, I need the money lol

Sure it's quite easy to fit it all in with two 9V batteries. It will be a lot easier to do it all SMD just use the filters on Farnell to find your parts if the existing ones don't have an SM equivalent. But I don't understand in your first post why you would use two 9V in series then try and split them into two 9V rails again? If your worried about DC offest don't be - your op-amps will keep the output voltage to what you want irrespective of the rails (to a point). You can also use voltage regulators instead however you will loose precious voltage. Look at this guys amp he made, he uses the same technique as I mention earlier and the THD is not measurable.

"The Wire" Ultra-High Performance Headphone Amplifier - PCB's - diyAudio

[HankMcSpank]

Post deleted - I made an error!

[Boscoe]

Post deleted - I made an error!

Oh yes sorry I do mention this in my above post too.

[HankMcSpank]

actually, no I'm still a little puzzled.

The schem shows two 9V batteries in series (connected back to back) then uses a rail splitter to provide a virtual ground (the mid point of the battery voltage) ....I'm curious why bother, why not just use signal ground which will always be pretty close to mid voltage anyway (yeah, sure the batteries might not fade with the same 'profile' but there won't be much in it to warrant the extra expense & component count of the virtual ground IC)

Edit: Actually the schem just shows a single 18V single battery! (but I'm assuming that will be implemented by 2 x 9V batteries?)

[Boscoe]

Yes that's basically what I say above!

[Fivetide]

Boscoe I did look at the "The Wire" ages ago , I never saw a schematic for it so never considered making one ,as for the TI headphone amp that looks amazing ! Link did you mean this one ? Because quite frankly TI have done all the hard work on the data sheet , might even buy the evaluation board ? Looking for schematic now :) thanks for the answer.

I mean really how simple does that look ? and 2 x 9v batteries to boot .. you are a star mate :)

[Fivetide]

I bought the board .. 1 left at Mouser so I got it .. hey i can always convert it to a headphone amp and for £48 quid ..not bad :)

[HankMcSpank]

Yes that's basically what I say above!

I must have been typing when you posted that one - great minds think alike eh?! lol.....

[Boscoe]

Boscoe I did look at the "The Wire" ages ago , I never saw a schematic for it so never considered making one ,as for the TI headphone amp that looks amazing ! Link did you mean this one ? Because quite frankly TI have done all the hard work on the data sheet , might even buy the evaluation board ? Looking for schematic now :) thanks for the answer.

I mean really how simple does that look ? and 2 x 9v batteries to boot .. you are a star mate :)

Don't worry about it! Happy to help.

[Fivetide]

Don't worry about it! Happy to help.

No I mean it I lost hope at one point , but this is awesome, when I've got a working one I'll PM u and send one to you :)