The capacitance determines the frequency response. The cap forms a high pass filter with your headphone speaker. The -3dB frequency of this filter is f = 1/(2 PI x Z x C) where Z is the impedance of your headphones. As you can see, a smaller capacitor will pass less bass - how much less depends on the impedance of your headphones.
The capacitance determines the frequency response. The cap forms a high pass filter with your headphone speaker. The -3dB frequency of this filter is f = 1/(2 PI x Z x C) where Z is the impedance of your headphones. As you can see, a smaller capacitor will pass less bass - how much less depends on the impedance of your headphones.
It's not just the capacitor and headphones though. You also have to take into account the input impedance of the amplifier you're using. I think a typical amp has about 10Kohm to 50Kohm of impedance, so that in conjunction with the headphones determines the bass response. Assuming you're using Grados at 32ohm impedance and an amp with 50K input impedance and 47uF BGs,
f = 1/(2*pi*(50,000+32)*47uf)
f = 1/(2*pi*50,032**0.000047)
f = 0.0677Hz
Like dumbears, I went with a slightly smaller capacity 22uF BG NX Hi-Q, but even that has a corner frequency of 0.145Hz with this theoretical setup. I think typical CMoy setups have around 20K input impedance. I'd say worry about the amp's impedance rather than the caps.
dumbears:
As for your iPod photo, if you could take an aerial shot of the WM8975 perhaps I can help you a bit better. From that angle I can't see the necessary traces. I don't think shorting the caps will make that much of a difference, as the goal is to completely avoid the internal circuitry. I haven't looked into it extensively, but I imagine you could solder the wires from the traces to the iPod's dock. I hadn't even thought of doing it that way. I'll look into it tonight. It would make things a lot cleaner. *wanders off in thought*
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Team University-fi | Team Edmonton-and-Surrounding-Urbanities(1)(2)
i just bought some BG caps off another member, hopefully I can do my 4th gen later~!
a little OT, but if someone is looking for a cheap silver 2nd gen Ipod nano (4gb) to purchase for testing on, give me a shout.
I have one (missing the plastic protect cover), I just installed a new LCD screen (works perfectly now), and I believe it needs a new battery too (battery doesn't hold). Everything works, except the body is a bit bruised (I have a new case for it though), and the click wheel turns flawlessly, but you need to press hard in order for the menu buttons to work.
True, 20Hz is the maximum threshold. Even if it's the oft-quoted limit, I doubt many can hear or distinguish the difference between 20Hz from 30Hz from 80Hz without special equipment. But that's a whole other area we won't get into. All the same, the iMod, GPod and diyMod all have the potential for amazing bass.
Here's a startling reminder I had earlier today: the chip in the iPods all cost Apple under $5 each (from extrapolation). Be wary of the rave reviews of the iMod, GPod and even my own of the diyMod. In a match between the Wolfsons and, say, a Benchmark DAC1, my money is on the Benchmark (figuratively speaking, of course). I don't know what's inside a DAC1, but I'm guessing that the huge chassis isn't hiding anything smaller than the WM8975.
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"Ears that hear and eyes that see - the LORD has made them both." Proverbs 20:12
Team University-fi | Team Edmonton-and-Surrounding-Urbanities(1)(2)
Lol, thanks! I will have to do something about this.
I got my nano which was supposable need just to replace battery and its dead but I have coming another one in a few days.
Also I took apart my nano and it’s possibly that I be able to squeeze two 47mF Simic II caps. Simic II is best ELNA electrolytic and quite few people prefer it to the BG.
In meanwhile I am working on second part of the mod, which is film caps dock for my nano.
but I have coming another one in a few days. 