[ruZZ.il]

Quote:

Originally Posted by bobby001 /img/forum/go_quote.gif I have a little problem : ...I still have sound when I use it without the blackgates (I tried in a soundstation). Is it normal ? I thought if I don't use a cable with BG caps I will hear noise and not the music : am I wrong ?

Wrong? not quiet. In fact, it's a sign that something is quiet all-right (well, potentially all all right).

The mod removes capacitors from inside the ipod. The capacitors job is to filter out DC (direct current). The ipod's signal is created on top of this DC, though this DC is what you don't want flowing through your headphones, cause it'll likely eventually damage them, and they wont be operating properly with it. They will nonetheless still be responding to the AC signal thats on top of that DC if they are still working, BUT, the line out is not meant to be fed directly in to headphones, rather in to a headphone amp, where that direct current could be amplified and become even worse! Some amps have coupling caps that will filter it out already, but you'd need to be certain of that before taking the risk. To be sure, we put capacitors in the signal path anyway, to block that DC, which we usually put in the line out cable, or some other contraption.
In short, is'd not a sign that things are wrong, but it's certainly not good practice to try and amplify that dc and feed it into your headphones. make sure there is a coupling capacitor in the signal path, either in a cable, or at the input of your amp...
I hope this doesn't confuse you more

edit:
Ignore most of the circuitry, just take a look at the 2 right most voltage meters..

Input and output coupling

 

[bobby001]

I didn't use it directly with headphone : I just plug in an ipod soundstation

So for you it's normal (sorry but I don't really understand stuff about electricity

)

 

[joneeboi]

What Sound Station are you using? It could be that it works even with DC in the signal, we don't know. Do you notice weak bass in the sound coming through the speaker? Usually the bass frequencies suffer when there is DC (experience drawn here from CMoy build). Going out on a limb here, I think the speaker/headphone driver is displaced a certain distance from its no-signal state thanks to the DC. From there, the music coming through will displace the magnet, but not as much as with a DC-free signal because it's already off-centre. If I understand correctly, there should be at least 2VDC at the input of the Sound Station. I don't recommend extended use of the iPod and Sound Station in this manner, as you'll likely destroy the speaker in the Station.

But who knows?

edit: That's a really nice diagram, Russ. Thanks for linking it.

 

[ruZZ.il]

Quote:

Originally Posted by bobby001 /img/forum/go_quote.gif So for you it's normal...?

Well, yes.
There IS a signal when using a normal line out dock, but that signal has a component that NEEDS(!) to be filtered out with a capacitor in line somewhere.
The signal, even with the DC, will cause an amplifier to play sounds on a speaker, but is NOT good practice. So, your mod is probably ok, but you NEED to use a cap

 

[mbarry]

Quote:

Originally Posted by Hayduke /img/forum/go_quote.gif I think I understand what you're saying. That was my original plan too. I was going to run wires from the DAC to unused pins on the dock connector, then make 2 LOD's to compare them. I like the idea of a switch in the LOD. It would be something to build just for that one experiment though

I'm sorry I'm bad with abbreviations. What does LOD stand for?

 

[dir_d]

Quote:

Originally Posted by mbarry /img/forum/go_quote.gif I'm sorry I'm bad with abbreviations. What does LOD stand for?

Pretty sure its Line Out Dock but i could be wrong

 

[dir_d]

Ive been watching this thread and was ready to purchase an ipod to start my own DIYmod but i decided to go with a Toshiba Gigabeat with rockbox instead. What you guys have done is amazing and i think i might still buy an ipod, try the DIYmod and pass the gigabeat to the finacee. Only part that stops me is making the LOD with the caps in it.. Im not that great soldering

 

[joneeboi]

Well, there's good news for you, dir_d, if you're not all that great at soldering because you'll get plenty of practice with the iPod dock. You only need three pins in your capped cable and you're supplied with 30, so if you mess some up, you have plenty upon which you can fall. Believe me when I say that when you learn to solder an iPod dock well, you can solder almost anything. Pick up two or three docks in case you want to make a few, and you can re-use those pins too. Once you get going, you get a pretty healthy supply. Just keep trying and you will get it.

And if all else fails, we have a good roundup of vendors at head-fi DIY that would gladly whip you up a cable for a decent price. Who have we got? ruZZ.il, stevenkelby, soloz, fatman711, and the list goes on. Search (key word there) and ye shall find.

Here's to your diyMod adventures. *lifts iPod dock into air with vigour*

 

[dir_d]

Quote:

Originally Posted by joneeboi /img/forum/go_quote.gif Well, there's good news for you, dir_d, if you're not all that great at soldering because you'll get plenty of practice with the iPod dock. You only need three pins in your capped cable and you're supplied with 30, so if you mess some up, you have plenty upon which you can fall. Believe me when I say that when you learn to solder an iPod dock well, you can solder almost anything. Pick up two or three docks in case you want to make a few, and you can re-use those pins too. Once you get going, you get a pretty healthy supply. Just keep trying and you will get it. And if all else fails, we have a good roundup of vendors at head-fi DIY that would gladly whip you up a cable for a decent price. Who have we got? ruZZ.il, stevenkelby, soloz, fatman711, and the list goes on. Search (key word there) and ye shall find. Here's to your diyMod adventures. *lifts iPod dock into air with vigour*

Thx for the pep talk...I think im gonna try to make a Gigabeat LOD 1st(if its possible). Then ill try the diymod\lod when i get more funds. You might get some PMs from me since im not crystal clear on some things.

 

[mbarry]

What pins in the dock are unused? I think i'm going to go with attaching wires in parallel with the original Line Out and having those wires go to 2 unused pins in the dock. Then I'll make a corresponding 30 pin connector with the Caps in them. I'm still debating whether or not to actually do this. I've never soldered anything so small, and the only thing I have ever done inside an iPod was to replace parts. And even doing that while grounded I still managed to fry an iPod's mainboard. Maybe the next time I open up my iPod to replace a battery or something I'll perform the DiyMod.

 

[bobby001]

the only used is the 2, 3 and 4 for the audio.

2 is the audio ground
3 is the right
4 is the left

 

[Hayduke]

Quote:

Originally Posted by bobby001 /img/forum/go_quote.gif the only used is the 2, 3 and 4 for the audio. 2 is the audio ground 3 is the right 4 is the left

Pin 1 is also ground. Some folks prefer to use that one, but I don't think it makes a difference in SQ.

 

[ruZZ.il]

Quote:

Originally Posted by mbarry /img/forum/go_quote.gif What pins in the dock are unused? I think i'm going to go with attaching wires in parallel with the original Line Out and having those wires go to 2 unused pins in the dock. Then I'll make a corresponding 30 pin connector with the Caps in them. I'm still debating whether or not to actually do this. I've never soldered anything so small, and the only thing I have ever done inside an iPod was to replace parts. And even doing that while grounded I still managed to fry an iPod's mainboard. Maybe the next time I open up my iPod to replace a battery or something I'll perform the DiyMod.

This is just slightly confusing. take a look at ipod pinout at pinouts.ru. You'll notice pins 7, 14 and 17 are unmentioned. I used 14 and 17 so they are verified to be unused in my nano but the access was a bit of a pain. a different ipod may have different access. I warn you though, that these pins are VERY small, and pretty tough to handle. I think if you'r capable of it, you should know what to do. The confusing this is the numbering though. the numbering at pinout.ru is INVERSED fram that marked on the board. It's not hard to figure out though. if you're looking at your ipod screen like you normally would, according to pinout.ru, pin number 1 is on the left, when you flip the ipod over and work from the back, it'll be to your right. I suggest you have this covored before tackling anything, and make sure you know what you're doing.
Good luck

 

[joneeboi]

For all iPods (AFAIK), pins 1, 2, 15, 16, 29 and 30 are all internally connected, so there isn't a difference between "audio" and "regular" grounds. I prefer to use the grounds other than 1, 2 because it reduces clutter inside the dock and lowers the chance of shorting anything. For the iPhone, you want to connect pin 11 to ground (preferably 15/16 but any will do) in order to get any music from the dock, so you could kill two birds by soldering your "audio" ground wire to the jumper between 11 and 15.

 

[mbarry]

Quote:

Originally Posted by ruZZ.il /img/forum/go_quote.gif This is just slightly confusing. take a look at ipod pinout at pinouts.ru. You'll notice pins 7, 14 and 17 are unmentioned. I used 14 and 17 so they are verified to be unused in my nano but the access was a bit of a pain. a different ipod may have different access. I warn you though, that these pins are VERY small, and pretty tough to handle. I think if you'r capable of it, you should know what to do. The confusing this is the numbering though. the numbering at pinout.ru is INVERSED fram that marked on the board. It's not hard to figure out though. if you're looking at your ipod screen like you normally would, according to pinout.ru, pin number 1 is on the left, when you flip the ipod over and work from the back, it'll be to your right. I suggest you have this covored before tackling anything, and make sure you know what you're doing. Good luck

Thanks for the info. So pins 7, 14, and 17 are unused by anything correct?, or are they just unknown? And if I solder the wires onto 14, and 17, it would not affect the original functionality whatsoever (Docking speakers, data transfer etc) right? Thanks again.