Rockbox General > Rockbox General Discussion

Sansa - prolonged electrical noise when loading tracks

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mgl888:
I'm using r14196-070805, which I just updated, but the slow/choppy list problem seems to be still there. Scrolling quickly (or trying to at least) through long song lists during playback results in regular short pauses. Could it just be that the Sansa processor is slow?

Vortex:
I'm experiencing that too. It's probably because the Original Firmware can use both cores of the Sansa's processor while Rockbox cannot.

dedalus:

--- Quote from: Vagabund on July 01, 2007, 04:54:49 AM ---Hi vitess,

i have with my Sansa e270 the same problem. But i can hear also the noise while changing in the menu with the scroll wheel. But the noticeable noise is the "tic-tic-tic" electrical noise always if i play a song or in the pause. This is for me the absolut K.O. criterion for Rockbox, sadly. I like Rockbox, but the primary job for the player is to play music in good sound quality. I hope for a solution.

My inear from UltimateEars the superfi 5 pro has 21 Ohms.

Regards
Michael

--- End quote ---

You are going to experience this with a lot of portables on various firmwares. There just doesnt' seem to be a lot of manufacturer testing going on for low-Z headphones and they like to sell ridiculously hot analog sections as a "feature." Not sure if there is anyway for the rockbox devs to lower the gain from firmware, it is probably a fixed path. I'm working on a simple L-pad inline attenuator to bring my SE310s up to an impedence that the sansa is more comfortable with. Maybe even just a single resistor inline like those ER-4 adapters.

Query: Is the attenuation for the Euro versions implemented in hardware or via DSP in the manufacturer's firmware? If the analog gain is actually lower in hardware, the Euro versions might be the way to go for low-Z headphones.

EDIT: Wanted to clarify that I meant testing by the manufacturers and not RB devs as I have no idea what phones are used in RB testing.

saratoga:
They all use the same amp hardware (its built into the PP5024 processor so its not like you can change it out).

The noise probably has nothing to do with the amp anyway.  It sounds like poor analog design work leading to cross talk.

dedalus:

--- Quote from: saratoga on October 05, 2007, 05:51:42 PM ---The noise probably has nothing to do with the amp anyway.  It sounds like poor analog design work leading to cross talk.

--- End quote ---

The noise all but disappears under load though when the volume is turned up in RB. Which is why I thought lowering the gain on the amp would help as the signal from the dac could be ratcheted up.

Had no idea the dac and amp were integrated on the processor though. The noise bust be coming in somewhere later between the processor and the headphone jack then. Leaves us pretty much no choice but to run it hot and attenuate it afterwards.

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