robjrock
100+ Head-Fier
- Joined
- Jan 14, 2009
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Part One: Complete noob guide.
Part Two: Some more basic question & answers.
Part Three: The 'how to' guide.
BEFORE PROCEEDING PLEASE READ MY DC OFFSET WARNING!!!!
Part One
"What is a P3 LOD?"
LOD stands up line out dock, but in this case it is really a line out cable. It allows the user to take audio from the USB connection port at the bottom of the player instead of the headphone jack. The main advantage of this is to get a 'line out' signal rather than a standard 'headphones out' signal. This would be most advantageous when using an external headphone amplifier, or plugging the P3 into a home stereo.
"What is a line out signal?"
Basically there are three things required to make any MP3 player work. These three things are a digital audio file, DAC and amplifier.
Firstly the music has to be stored in some kind of file, such as an Mp3, Wav, Flac, Ogg, Wma etc. Secondly, you need something to turn that digital audio file (Mp3 etc) into an analogue signal our ears can hear (IE: music). The DAC, or digital to analogue converter does this. Finally you need something to make it louder / quieter (volume control), add EQ effects like bass boost (DSNe) etc. This is where the amplifier steps in.
In theory, the P3 LOD would be taking the audio directly from the DAC (digital to analogue converter) effectively bypassing this internal amplifier. This is normally called a 'line out' connection. The line out would then be plugged into an external amplifier, as mentioned earlier. The idea is you will get a more 'pure' sound by avoiding having the music amplified twice.
"But my P3 sounds great, why bother with an external amp / LOD?"
You bet the P3 does sound great on its own. However like any Mp3 player, it can sound even better when used with a quality external amp. A small percentage of people will always look for the best sound quality they can get, even if it means slicing up a cable. Although the P3 sounds great, the tiny little surface-mounted built-in amp can't quite compete with a quality external amp. It pushes the sound quality to the extreme.
Part Two:
"Who should / can build this?"
Firstly you'll need access to a spare cable. In theory any cheap aftermarket cable will do. I got mine for £2.50 on eBay. Don't do this unless you have a spare cable. Secondly it requires some pretty tricky soldering, although the actually idea is quite simple. De-solder 3 pins, slide pins into appropriate slots, re-solder pins to cable. But all three pins are extremely close together and very small. I would consider this an 'intermediate' project, but really about the worse you can do is mince a cheap aftermarket cable.
"Is it true line out?"
Well the short answer is I don't know. The slightly longer answer is 'probably not' - for starters you can still use volume and DSNe effects, which is a pretty good sign its not coming straight from the DAC. Also as mentioned below, I see no different in DC output. It does sound different, but its not a gigantic difference. So unless someone with some knowledge is willing to do a tear-down, or unless someone with some influence finds out direct from Samsung (*cough cough, hint hint*) I guess probably not is the best answer.
It should be noted that the Sansa Fuze is said to have true line out yet it allows you to access volume and EQ when using a LOD, something to do with the chip configeration or something. So who knows?
Part Three:
Okay, a couple of things first.
One: So far I have not been able to detect any DC offset. This actually makes me a little more worried than actually detecting some, because I'm starting to think I'm not measuring it correctly. Anyway, many LODs produce potentially headphone damaging amounts of DC offset, so you're external amplifier will need DC protection, such as input capacitors. To learn more about this try clicking here:
Measuring DC offset
Please make sure you understand this before proceeding.
Two: I was a bit of an idiot and used the official Samsung cable instead of the cheap aftermarket cable because I didn't think it had the right pins. Turns out it did (I'm pretty sure). These instructions are a general guide only, there are probably much smarter ways of doing this. My method involved dosoldering / resoldering each pin individually to the cables; however please bare in mind I was doing this for the first time, without any help from guides etc so I did the best I could. Feel free to comment with improvements though. Also the pictures of my cable will probably look different from your cable, but the general idea will be the same, so don't stress it.
I used this
http://*********.com/files/P2/Servic...P2-e-6-pcb.pdf
and this
http://www.head-fi.org/forums/f6/san...de-56k-421318/
as my basis for building the cable. May make for some interesting reading if my guide is too vague for you.
EDIT: Ok, its editing a URL, so just google Samsung P2 PCB layout. I used this assuming (correctly) they would use the same pin outs as both the P2 and P3 cable are the same!
Okay, lets go.
First of all you'll need to disassemble your cable. Both my cables simply required two screws to be removed, and then I used a stanley knife to pry it open: it may have two clips up the top which should open with a little pry.
Inside there should be about 7 'pins' with stick into the connector. You'll need to get three of those pins into pin numbers 17, 18, 19. Look at the picture below.
The view is 'from behind' the plug. Pin number 1 is on the far left and pin 24 is on the far right. It is easier to count back from 24 IMO. You can see here I removed the little PC board altogether, removing the pins and placing them individually into the slots. However, soldering them this way to the cable is very difficult. In retrospect disoldering the entire pin from the board (not just the end bit) and resoldering them back onto the board may have worked better. The cable will probably have 4 cables, you will only need three.
Pin 17 is audio right.
Pin 18 is audio left.
Pin 19 is ground.
Think really carefully about how you are going to solder the pins so close together, and count very carefully. You will need to remove the metal bit on the outside of the plug to access the pins properly.
When you have inserted the pins, in the right light you should be able to see them from the 'front view' of the cable. They need to be pushed in fairly far.
Okay, now hook up each pin to a cable. Write down which colour is connecting to which pin. Try to keep the wires at an even length so there is no 'pull' on a particular pin. You may or may not omit the little PC board, its up to you. It may be easier to keep it. Any spare pins don't throw out, your soldering may come loose and a pin may break. You may need spares.
Once the wires are soldered to the pins you've done the hardest part. If you want to test your connection reassemble the connector with the metal bit and the outter shell if you like. Insert into the P3, make sure your in headphone and not speaker mode, and see if you can some weak audio signal from the left and right channel. Without ground connected it will be very quiet, but you should get a weak signal. Don't bother trying to touch the wire to your headphone stereo jack, it will need to be pressed against the input jack on your amp or something. Once your happy, solder the three wires to a stereo jack and clean it up a bit. I used some heatshrink near the P3 connection to try to stop the cable from swiveling at this end. If your don't stop it from swiveling your soldering will come loose, trust me!
How does it SOUND!????
Good question. I would love to hear some other peoples opinions, so I'm not going to say too much here. Basically to my ears its a shade louder, maybe 10%. Also its a bit fuller sounding, not as 'dry' as the headphone out. Maybe sound-stage is a tad wider, not as 'mushy' - no particular part of the music really changes, maybe the bass is a tad fuller. Overall, to my ears, it sounds glossier, fuller, richer. And yes, better. But we're talking about pushing the last 5-10 percent out of an already great sounding player. But yeah, its good.
One little side note, I was having problems with the cable and my LM4562 op amp, it was only playing when I used my fingers to 'ground' the channels - no other op amp had that problem. So I am using my OPA2277 now, which sounds good, but is not as detailed or intense. A really detailed op amp may show some more differences between the LOD and headphone out!
So what are you waiting for. Crank out that soldering iron!
Part Two: Some more basic question & answers.
Part Three: The 'how to' guide.
BEFORE PROCEEDING PLEASE READ MY DC OFFSET WARNING!!!!
Part One
"What is a P3 LOD?"
LOD stands up line out dock, but in this case it is really a line out cable. It allows the user to take audio from the USB connection port at the bottom of the player instead of the headphone jack. The main advantage of this is to get a 'line out' signal rather than a standard 'headphones out' signal. This would be most advantageous when using an external headphone amplifier, or plugging the P3 into a home stereo.
"What is a line out signal?"
Basically there are three things required to make any MP3 player work. These three things are a digital audio file, DAC and amplifier.
Firstly the music has to be stored in some kind of file, such as an Mp3, Wav, Flac, Ogg, Wma etc. Secondly, you need something to turn that digital audio file (Mp3 etc) into an analogue signal our ears can hear (IE: music). The DAC, or digital to analogue converter does this. Finally you need something to make it louder / quieter (volume control), add EQ effects like bass boost (DSNe) etc. This is where the amplifier steps in.
In theory, the P3 LOD would be taking the audio directly from the DAC (digital to analogue converter) effectively bypassing this internal amplifier. This is normally called a 'line out' connection. The line out would then be plugged into an external amplifier, as mentioned earlier. The idea is you will get a more 'pure' sound by avoiding having the music amplified twice.
"But my P3 sounds great, why bother with an external amp / LOD?"
You bet the P3 does sound great on its own. However like any Mp3 player, it can sound even better when used with a quality external amp. A small percentage of people will always look for the best sound quality they can get, even if it means slicing up a cable. Although the P3 sounds great, the tiny little surface-mounted built-in amp can't quite compete with a quality external amp. It pushes the sound quality to the extreme.
Part Two:
"Who should / can build this?"
Firstly you'll need access to a spare cable. In theory any cheap aftermarket cable will do. I got mine for £2.50 on eBay. Don't do this unless you have a spare cable. Secondly it requires some pretty tricky soldering, although the actually idea is quite simple. De-solder 3 pins, slide pins into appropriate slots, re-solder pins to cable. But all three pins are extremely close together and very small. I would consider this an 'intermediate' project, but really about the worse you can do is mince a cheap aftermarket cable.
"Is it true line out?"
Well the short answer is I don't know. The slightly longer answer is 'probably not' - for starters you can still use volume and DSNe effects, which is a pretty good sign its not coming straight from the DAC. Also as mentioned below, I see no different in DC output. It does sound different, but its not a gigantic difference. So unless someone with some knowledge is willing to do a tear-down, or unless someone with some influence finds out direct from Samsung (*cough cough, hint hint*) I guess probably not is the best answer.
It should be noted that the Sansa Fuze is said to have true line out yet it allows you to access volume and EQ when using a LOD, something to do with the chip configeration or something. So who knows?
Part Three:
Okay, a couple of things first.
One: So far I have not been able to detect any DC offset. This actually makes me a little more worried than actually detecting some, because I'm starting to think I'm not measuring it correctly. Anyway, many LODs produce potentially headphone damaging amounts of DC offset, so you're external amplifier will need DC protection, such as input capacitors. To learn more about this try clicking here:
Measuring DC offset
Please make sure you understand this before proceeding.
Two: I was a bit of an idiot and used the official Samsung cable instead of the cheap aftermarket cable because I didn't think it had the right pins. Turns out it did (I'm pretty sure). These instructions are a general guide only, there are probably much smarter ways of doing this. My method involved dosoldering / resoldering each pin individually to the cables; however please bare in mind I was doing this for the first time, without any help from guides etc so I did the best I could. Feel free to comment with improvements though. Also the pictures of my cable will probably look different from your cable, but the general idea will be the same, so don't stress it.
I used this
http://*********.com/files/P2/Servic...P2-e-6-pcb.pdf
and this
http://www.head-fi.org/forums/f6/san...de-56k-421318/
as my basis for building the cable. May make for some interesting reading if my guide is too vague for you.
EDIT: Ok, its editing a URL, so just google Samsung P2 PCB layout. I used this assuming (correctly) they would use the same pin outs as both the P2 and P3 cable are the same!
Okay, lets go.
First of all you'll need to disassemble your cable. Both my cables simply required two screws to be removed, and then I used a stanley knife to pry it open: it may have two clips up the top which should open with a little pry.
Inside there should be about 7 'pins' with stick into the connector. You'll need to get three of those pins into pin numbers 17, 18, 19. Look at the picture below.
The view is 'from behind' the plug. Pin number 1 is on the far left and pin 24 is on the far right. It is easier to count back from 24 IMO. You can see here I removed the little PC board altogether, removing the pins and placing them individually into the slots. However, soldering them this way to the cable is very difficult. In retrospect disoldering the entire pin from the board (not just the end bit) and resoldering them back onto the board may have worked better. The cable will probably have 4 cables, you will only need three.
Pin 17 is audio right.
Pin 18 is audio left.
Pin 19 is ground.
Think really carefully about how you are going to solder the pins so close together, and count very carefully. You will need to remove the metal bit on the outside of the plug to access the pins properly.
When you have inserted the pins, in the right light you should be able to see them from the 'front view' of the cable. They need to be pushed in fairly far.
Okay, now hook up each pin to a cable. Write down which colour is connecting to which pin. Try to keep the wires at an even length so there is no 'pull' on a particular pin. You may or may not omit the little PC board, its up to you. It may be easier to keep it. Any spare pins don't throw out, your soldering may come loose and a pin may break. You may need spares.
Once the wires are soldered to the pins you've done the hardest part. If you want to test your connection reassemble the connector with the metal bit and the outter shell if you like. Insert into the P3, make sure your in headphone and not speaker mode, and see if you can some weak audio signal from the left and right channel. Without ground connected it will be very quiet, but you should get a weak signal. Don't bother trying to touch the wire to your headphone stereo jack, it will need to be pressed against the input jack on your amp or something. Once your happy, solder the three wires to a stereo jack and clean it up a bit. I used some heatshrink near the P3 connection to try to stop the cable from swiveling at this end. If your don't stop it from swiveling your soldering will come loose, trust me!
How does it SOUND!????
Good question. I would love to hear some other peoples opinions, so I'm not going to say too much here. Basically to my ears its a shade louder, maybe 10%. Also its a bit fuller sounding, not as 'dry' as the headphone out. Maybe sound-stage is a tad wider, not as 'mushy' - no particular part of the music really changes, maybe the bass is a tad fuller. Overall, to my ears, it sounds glossier, fuller, richer. And yes, better. But we're talking about pushing the last 5-10 percent out of an already great sounding player. But yeah, its good.
One little side note, I was having problems with the cable and my LM4562 op amp, it was only playing when I used my fingers to 'ground' the channels - no other op amp had that problem. So I am using my OPA2277 now, which sounds good, but is not as detailed or intense. A really detailed op amp may show some more differences between the LOD and headphone out!
So what are you waiting for. Crank out that soldering iron!
