The Apple diyMod: My Take on the Famous iMod [56k killer] Featuring 3G, 4G, 5G and nano 1G! - Page 94 - Head-Fi: Covering Headphones, Earphones and Portable Audio

joneeboi · #**1396** (**permalink**) 09-21-2008, 11:57 PM

It seems people are pretty anxious to get the diyMod touch. I tried, but it seems impossible to see where the signal goes to from the DAC. I even got a mini microscope to do some sleuthing and investigating, but I think Apple might have sent the signal underneath the chip itself. There is a bit of metal shielding that hides the chip away, so seeing the traces is near impossible. I could probably Dremel it away, but that is an ugly solution that doesn't even guarantee success. Maybe the skillful solderer can get the wire onto the chip's pads, but that's also risky. I'm not sure where to go with it just yet.

Hayduke · #**1397** (**permalink**) 09-22-2008, 08:37 PM

Quote:

Originally Posted by zeiner-rider

i was checking a car-amp with the headphone output as signal. Unfortunately i connected the output with Supply Voltage of the amp.

I think there is more dead. I cheked several caps, no one helped.

Looking at the pic you posted, I would be surprised if that cap was the only component damaged. I don't think I would even try to repair that mainboard, but the good news is replacements are easy to get. Here is one:
iPOD Video 5th Gen 5.5G Logic Motherboard Main Board - eBay (item 380064709426 end time Oct-16-08 07:33:58 PDT)

Good luck and let us know what happens.

zmorris · #**1398** (**permalink**) 09-24-2008, 11:14 AM

When there's a solution for the new 4G nano, what caps would be suitable for this mod and can fit inside the nano? There's a slight gap next to the battery which may be a perfect spot to place them.

bidoux · #**1399** (**permalink**) 09-24-2008, 01:35 PM

Why does the DIY mod usees more battery than the non-moddded one ?
Because the amp section is kicked off, it should have even more battery

.

joneeboi · #**1400** (**permalink**) 09-25-2008, 07:33 PM

zmorris:

If a solution presents itself in the nano 4G, it will likely be the shorting of DAC outputs to dock.

bidoux:

Where are you getting reports of shorter battery life? I can only think of people's diyMods malfunctioning or batteries dying like they are prone to do, but I can't remember someone mentioning shorter battery life. Theoretically, you'd be correct, but I don't know where people are finding these amp sections. I've only found CRL filters after the DACs, but no amps. Could that be what the DZP chips are doing?

Hayduke · #**1401** (**permalink**) 09-25-2008, 07:52 PM

Quote:

Originally Posted by bidoux

Why does the DIY mod usees more battery than the non-moddded one ?
Because the amp section is kicked off, it should have even more battery

.

The mod shouldn't affect battery life enough that you would notice. Where are you reading this?

There IS an issue with Rockbox and battery life with iPods in general. This has nothing to do with the mod, but I suspect a lot of folks that mod their iPods also run Rockbox. Perhaps that's the cause of decreased battery life?

bidoux · #**1402** (**permalink**) 09-26-2008, 04:21 PM

Thank you guys!
I saw it but maybe I didn't understand well the point.

The man was talking about his Imod
(not DIY mod) and said that with Rockbox on it and the mod the battery life is very shorter.

But you think that the DIY mod doesn't kill battery life. Does it make be longer ?

I have another question, if I do this mod can I make it go to the jack output. That way I won't need a special LOD?

Edit: Last question, what kind of caps do I have to put after the line out ?

joneeboi · #**1403** (**permalink**) 09-26-2008, 08:50 PM

I have heard of RockBox killing battery life, but I honestly couldn't tell you with the diyMod.

As for sending the signal to the headphone out, you can most certainly do that. I didn't think of it your way, but I figure if you're going to be doing all this DIY, you might as well whip up your very own LOD. Then again, it does take quite a bit of know-how to get it really good. I'm still experimenting with the perfect way to make a reliable LOD. Yeah, whichever way you want, it's all good.

Finally, one of the advantages of the diyMod is you get to select the type of caps you want to use. Experiment and read reviews, check the front page for a few links on the subject. You're not tied down to any type of capacitor, but you can try out whatever until you find one you're satisfied with. Good luck.

Hayduke · #**1404** (**permalink**) 09-26-2008, 08:59 PM

Quote:

Originally Posted by bidoux

The man was talking about his Imod
(not DIY mod) and said that with Rockbox on it and the mod the battery life is very shorter.

That's the reason

Quote:

Originally Posted by bidoux

But you think that the DIY mod doesn't kill battery life. Does it make be longer ?

Why would it help battery life? Isn't the line out a full power signal? You can think of the internal amplifier as sort of a variable attenuation function to allow volume control (I know this isn't 100% accurate, but it works for my thinking). The internal doesn't use up more power sending the signal to your headphones, so this mod shouldn't affect battery life.

Quote:

Originally Posted by bidoux

I have another question, if I do this mod can I make it go to the jack output. That way I won't need a special LOD?

Edit: Last question, what kind of caps do I have to put after the line out ?

If you route the "cleaner" line out signal to the headphone jack, you may still need coupling caps, the same as via the dock connector. Of course, this depends on your amplifier. Some amps have caps on the inputs already, but in this case you don't need an LOD with caps built in.

I'm rereading this and it's about as clear as mud huh? :P

As to what type of caps, one of the more popular choices are 47uf Blackgates. I'm don't know enough about the high end audio caps to say much more.

ruZZ.il · #**1405** (**permalink**) 09-27-2008, 01:29 AM

well, in terms of power usage, the fact that the line out has larger voltage swings doesn't mean everything since the current it drives into a high impedance input of an amplifier is much lower than it would be feeding into headphones (V*I=V^2/R). Assuming even a gain of 1 the amplifier does more of the 'work' since its feeding the same voltage into a much smaller impedance.. So using an external amplifier and it own power source should actually mean less work for the ipod to have to do.. so there must be something else if the consumption is higher using the line out.

suicidal_orange · #**1406** (**permalink**) 09-27-2008, 10:22 AM

The rockbox battery problem is fixed as of ages ago from my experience (I get ~12 hours out of a 5.5g 30gb model which has less RAM so uses the hard drive more than the 60/80gb) and that is using flac files. I turn the volume all the way down as it doesn't effect the line out volume anyway - not sure if it shuts down the amp section but it can't hurt

Also I did my first DIY mod yesterday on a 5.5g 80gb "dead hard drive" model from ebay, and it works

I'm quite surprised as my soldering iron is far from fine tipped, and I'm not experienced but for about $45 it was a risk worth taking. Nothing special to note, and no research required thanks to having a RWA imod with a clear front to reference to, which agrees with the instructions in this thread exactly!

I then found this formula for working out which caps would be good for a given setup, but am not sure what a good answer is - can anyone help?

Quote:

f = 1/(2*pi*(50,000+32)*47uf)
f = 1/(2*pi*50,032**0.000047)
f = 0.0677Hz

I've got a PA2V2 on the way which is around 10,000 at the input (I'm putting together a cheap package to convince others this mod is worthwhile!) and it will be used only with IEM's or earbuds, so compared to 10,000 not enough to bother adding to the equation.

Thanks

bidoux · #**1407** (**permalink**) 09-27-2008, 01:09 PM

Thanks for the answers, I will first do some caps before doing the LOD and the mod.
I know, I'm a bit weird.

I'm looking for caps that I can find at my local electronic store.

What are the name of it, the µf and the V ?

Something like this.

joneeboi · #**1408** (**permalink**) 09-27-2008, 02:50 PM

suicidal_orange:

Yeah, that equation is a bit off. It's supposed to just be the input impedance of the amplifier, so scratch out that "+32" there.

bidoux:

Those capacitors are Black Gate NX Hi-Q, the same ones RedWineAudio uses. You can't see the markings, but I think from the width, it looks like the 47uF 6.3V I have as well. You likely aren't going to find that in the local electronic store, but specs you'd want to watch for are 4V< and, coming from the equation suicidal_orange used,

C = 1/(2*pi*Z*f)

with Z as the input impedance of whatever amplifier you're using,
f as the corner frequency (anything between 20Hz and 0Hz, really)

You're probably better off ordering from Farnell though.

bidoux · #**1409** (**permalink**) 09-27-2008, 04:16 PM

I think Joneeboy you noticed that I'm French so it's hard for you to understand me.

I wasn't talking about the auricap's one but rather the idea of this picture, that is adding lots of capacitors.

joneeboi · #**1410** (**permalink**) 09-27-2008, 04:43 PM

Si vous voulez parler en Francais, peut etre ce sera plus facile pour vous.

vvs_75 would know more about that particular arrangement, but typically, you can just put one capacitor in series with the DAC. People have been bypassing capacitors for I-don't-know-how-long, but even in such new designs as amb's gamma-1 DAC, there are positions for a coupling and bypass capacitor, though in the headwize thread, there was mention that bypassing wasn't really necessary. I don't really know, I just attribute it all to the voodoo and magic of audio that can't really be explained by numbers. Trust your ears.