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SanDisk Fanatic
Posts: 363
Registered: ‎08-02-2008

Re: DIY Line Out Cable - Works!

None of us has a clear understanding yet. Sansafix has provided some very useful info though. I need to get a complete schematic built of the Griffin Dock, hopefully in the next few days. All must realize that this work is being done blind. No complete Fuze pinout available and no chip pinout engineering data. This is proprietary info and probably will never be found. So tinkering is the way to solve it. Maybe at the price of a player if something goes wrong for me.

axon, I understand your justification for the dock now. Very handy for desk use and charging. This is assuming you get it at the clearance price as you have stated. Buying at full price would be very questionable. I bought one to disect it!

skinjob, My current cable jump I would call marginally useable. It seems that it is overdriving the output. People can try it and see if they run into distortion on their hookups. I'll dig out my old Hameg o-scope and see what the actual levels I'm dealing with are.

Since pin7 is a binary on/off enable input the voltage level means nothing, 1-3 volts is going to be the same.

I want to get the cable connected output level the same as the Dock output, as it is probably the cleanest signal available. It will also be proper if the peak to peak value is correct as "true" lineout. My next guess without tinkering is that there may be a pin or pins that get grounded when docked. The cable mod does work on enableing the lineout, but I feel it can be improved.

8GB Blue FUZE w/The Original DIY Lineout Cable and AT Button H-Phones Fitted To AT WM5 Headband:All Custom Built
SanDisk User
Posts: 76
Registered: ‎11-17-2008

Re: DIY Line Out Cable - Works!

sansafix, the 3 volts on pin 22, can they be used to power other devices? If yes, how many mA can safely be used?
SanDisk Professor
Posts: 682
Registered: ‎04-18-2008

Re: DIY Line Out Cable - Works!


Cruiserdude wrote:

This is great info, and its good to be able to get this much technical information on the inner workings of these devices.  Even better to hear that Sandisk is addressing this further for us.  I do, however, have two simple questions:

 

1) Would it be possible to enable line-out without requiring voltage to pin 7?  If so, what are the chances Sansa would allow this with a future FW upgrade, and what (if anything) would be their reasons for not doing so?

 

2) Why doesn't SanDisk want to make a cable?  Seems like it would be a great way to make some extra money, as well as increasing sales to people who buy Ipods instead due to the much greater accessory market.  I can understand that they want to sell their docks for home use, but it would be great for cars, as well as for the portability factor.  Seems like they'd be missing out NOT to make a cable, so what are the reasons against them doing this? 


 

1) Sansafix has indicated it is possible via FW, but they have decided not to do it.  You would need a setting to enable either the phones or the line-out.  Since you can't have both at the same time, I guess they were afraid users would set it to line and not be able to figure out why their headphones don't work.  Seems to me this could be handled easilly in the UI with some kind of status icon (for example, in the same way you know if shuffle is on or not).

 

2) I have no idea.  It makes no sense.  Especially since the official Sansa dock is so expensive.  I doubt that many people are willing to spend $50-60 on a dock, but I would think many would buy a $10-15 cable.  And as you said, a dock is not really useful for car and other portable applications.  And if they implemented an output switch in FW, you could use the existing View A/V cable.  They wouldn't need to make a special Fuze cable.

SanDisk Guru
Posts: 1,235
Registered: ‎10-24-2007

Re: DIY Line Out Cable - Works!

Dont try powering other devices from the Fuze,  its not supported.
SanDisk User
Posts: 49
Registered: ‎12-01-2008

Re: DIY Line Out Cable - Works!


14124all wrote:

None of us has a clear understanding yet. Sansafix has provided some very useful info though. I need to get a complete schematic built of the Griffin Dock, hopefully in the next few days. All must realize that this work is being done blind. No complete Fuze pinout available and no chip pinout engineering data. This is proprietary info and probably will never be found. So tinkering is the way to solve it. Maybe at the price of a player if something goes wrong for me.

axon, I understand your justification for the dock now. Very handy for desk use and charging. This is assuming you get it at the clearance price as you have stated. Buying at full price would be very questionable. I bought one to disect it!

skinjob, My current cable jump I would call marginally useable. It seems that it is overdriving the output. People can try it and see if they run into distortion on their hookups. I'll dig out my old Hameg o-scope and see what the actual levels I'm dealing with are.

Since pin7 is a binary on/off enable input the voltage level means nothing, 1-3 volts is going to be the same.

I want to get the cable connected output level the same as the Dock output, as it is probably the cleanest signal available. It will also be proper if the peak to peak value is correct as "true" lineout. My next guess without tinkering is that there may be a pin or pins that get grounded when docked. The cable mod does work on enableing the lineout, but I feel it can be improved.


Hi 1412

 

What I don't understand is this: 

 

  • If the lineout and the headphone jack (at 100%) are the same, how is it possible that your cable can output more than there is?
  • And if the lineout and the headphone jack produce the same signal, they should be able to be used interchangably.

 

  • And if they are interchangable, a true line level output can be obtained from the headphone jack at 100% while preserving the FM function.  [Regarding the FM function, while I was not able to get satisfactory reception with a .5M Zu Pivot, a plain, el cheapo, unshielded, Radio Shack 1M mini to RCA did the trick.]

 

axon

SanDisk User
Posts: 87
Registered: ‎11-21-2008

Re: DIY Line Out Cable - Works!


Skinjob wrote:

Cruiserdude wrote:

This is great info, and its good to be able to get this much technical information on the inner workings of these devices.  Even better to hear that Sandisk is addressing this further for us.  I do, however, have two simple questions:

 

1) Would it be possible to enable line-out without requiring voltage to pin 7?  If so, what are the chances Sansa would allow this with a future FW upgrade, and what (if anything) would be their reasons for not doing so?

 

2) Why doesn't SanDisk want to make a cable?  Seems like it would be a great way to make some extra money, as well as increasing sales to people who buy Ipods instead due to the much greater accessory market.  I can understand that they want to sell their docks for home use, but it would be great for cars, as well as for the portability factor.  Seems like they'd be missing out NOT to make a cable, so what are the reasons against them doing this? 


 

1) Sansafix has indicated it is possible via FW, but they have decided not to do it.  You would need a setting to enable either the phones or the line-out.  Since you can't have both at the same time, I guess they were afraid users would set it to line and not be able to figure out why their headphones don't work.  Seems to me this could be handled easilly in the UI with some kind of status icon (for example, in the same way you know if shuffle is on or not).

 

2) I have no idea.  It makes no sense.  Especially since the official Sansa dock is so expensive.  I doubt that many people are willing to spend $50-60 on a dock, but I would think many would buy a $10-15 cable.  And as you said, a dock is not really useful for car and other portable applications.  And if they implemented an output switch in FW, you could use the existing View A/V cable.  They wouldn't need to make a special Fuze cable.


Hmm, yeah, its wierd that they seem to be keeping quiet on their reasoning behind either of those questions.  I'm not calling them out by any means, and I certainly understand that sansafix can't tell us something if SanDisk doesn't want him to, but it still bugs me as to why they don't seem to want to give us a reason.
 Don't get me wrong, I'm very grateful that they're so involved here, and actually listen to our questions, problems, and requests, great customer feedback!  I just get very curious when I feel that the reasoning behind something is being hidden.
 At this point, all I can think of is that they are afraid of competition with the View, though this would be rather illogical.  The hardware on the Fuze does not enable a video-out, and due to the lower SQ, I doubt anyone will buy a View strictly for audio line-out purposes, so its not like they'd be robbing people away from the View.  (I hate to say it, but with the lower SQ, larger size, and higher price, the View isn't nearly as attractive a purchase, anyway, just my honest opinion.)  Regardless, I can understand certain reasons why they may not want to enable this in FW, though I still think it could at least be a rather hidden-away option for us more advanced users to enable.  Like, bury something in the system settings about enabling line-out, and if its "switchable", rather than "off", we'd have an extra icon on the home screen, or you could just hold the center button from the home screen, to switch between line-out and headphones.  That way we could take advantage of it, but the users who would get confused would never enable this option, anyway.  Then y'all could sell us an audio output cable and make some extra cash!

 

SanDisk Fanatic
Posts: 363
Registered: ‎08-02-2008

Re: DIY Line Out Cable - Works!

axon, These are only assumptions.

I don't think the lineout and headphone jack are the same signal. Going by the block diagram of the AMS chip, the headphone amp circuit is built into the chip (it does not seem to be an outboard IC with a preamp feed). The lineout (preamp) signal and headphone amp signal come out of the chip independantly. The lineout will be of high impedance (probably 10-20k ohm) to drive high impedance inputs. The amp out will be of low impedance (probably around 32 ohm) to drive low impedance headphones. Sansafix has stated that the lineout should produce the better signal to noise ratio, which is to be expected from a high impedance signal that does not go through another amp gain stage.

Why is my cable getting a stronger signal - good question. Wish I knew! Note that when you connect to the dock, the volume is adjustable to about 25% and then it does not increase. There is probably more there as calv has explained with his DAC explanation, but it is being limited to avoid signal degradation. Sansafix has also stated that it is at .7v rms p-p line level. The cable is no doubt higher than that. When connected to my Klipsch Promedia with the the Klipsch volume all the way down, I still get some  sound output. The input is being overdriven. Why? A big guess here! The AMS chip may have an adjustable preamp for the lineout, instead of being fixed. If it is uses op-amp circuitry and there is an open (floating) input, it may produce a higher gain on the op-amp output. So, if there is a connection in the Griffin dock that grounds an input, and my cable does not have it, it may produce more gain and a louder signal. Could also be that there is more to it than just enabling pin7. I hope to find out more when I get a full drawing together of the Griffin Dock circuit.

Are they interchangeable? Hard to say! If you can't hear much difference between amp out and dock out with your M3 and beyer DT880s, than a mini-RCA or mini-mini is probably fine in the headphone jack. I think what is killing us here is that the headphone out signal in the Fuze is overly good. It is very clean all the way up to full volume.

8GB Blue FUZE w/The Original DIY Lineout Cable and AT Button H-Phones Fitted To AT WM5 Headband:All Custom Built
SanDisk User
Posts: 76
Registered: ‎11-17-2008

Re: DIY Line Out Cable - Works!

Just want to remind you, that everything that uses phone jacks is prone to short circuits while inserting the plug. Adding resistors is the easiest way to prevent the current from going to "infinity" (which would fry ICs), but on the other hand it decreases the signal level. The size of the resistor that is needed to limit the current with a given max voltage can easily be calculated with ohm's law.
SanDisk Professor
Posts: 682
Registered: ‎04-18-2008

Re: DIY Line Out Cable - Works!


14124all wrote:

Sansafix has also stated that it is at .7v rms p-p line level. The cable is no doubt higher than that. When connected to my Klipsch Promedia with the the Klipsch volume all the way down, I still get some  sound output. The input is being overdriven.


 

 Maybe the change to a fixed line out in the upcoming FW that sansafix mentioined will improve this situation?

 

 


14124all wrote:

Are they interchangeable? Hard to say! If you can't hear much difference between amp out and dock out with your M3 and beyer DT880s, than a mini-RCA or mini-mini is probably fine in the headphone jack. I think what is killing us here is that the headphone out signal in the Fuze is overly good. It is very clean all the way up to full volume.


 

The heaphone out is definitely clean, the issue is really just the lower level.  I use it to connect to my car's head unit and it sounds pretty good.  However, to get a decent level, I have to MP3Gain to 92dB, boost the Fuze's EQ about halfway up across all freqencies and set the gain on the head unit's line-in to max.  With all that, I get a level appoximately the same as playing a CD in the head unit.  Despite all the boosting, it still sounds suprisingly good.  But surely a true line source with no EQ on the Fuze and no/moderate gain on the head unit's input would be a lot better.

 

SanDisk Professor
Posts: 682
Registered: ‎04-18-2008

Re: DIY Line Out Cable - Works!

@14124all - is this the same A/V you tried that didn't have the necessary pins?

 

SanDisk Sansa View AV ( Audio Video ) RCA Cable - 4.5 Feet

 

I have this one and was trying to open the 30-pin connector housing and couldn't figure out how to get into it without breaking it.  I also have a cheap data cable with the same 30-pin connector housing that I could try if the AV cable won't work.

 

How did you open the connector housing without breaking it?