Rockbox Technical Forums

Support and General Use => Recording => Topic started by: Recording Guy on February 27, 2010, 08:02:01 PM

Title: H10 Pure
Post by: Recording Guy on February 27, 2010, 08:02:01 PM
Hi,

Does anyone know if the line inputs and outputs need caps fitted on the cable before connecting to any external devices? For example a mic preamp and an amplifier

Couldn't find a circuit diagram for the cradle unit and I searched to the end of the internet ;)

And does Rockbox automatically short the cradle detect now as I got no instruction to "put the thing on the cradle" message that the IRiver software tells me to. Well thats one less thing to cock up, er solder.. ;)

Thanks.
Title: Re: H10 Pure
Post by: saratoga on February 27, 2010, 08:14:41 PM
I doubt rockbox bothers to detect a dock.  It'll probably just power up the line in whenever you tell it to record, dock connected or not. 
Title: Re: H10 Pure
Post by: Recording Guy on February 27, 2010, 09:23:26 PM
Thanks for that,

I am getting a fluctuating signal on the left input about -78db
and the right input is steady at about -84.3db. This is without any cable connected
and line gain set at 0db. Tried turning off LCD, no difference.

Tried various sample rates 44.1, 48, 96 khz no difference.

I Have attached a sample of it (Rename.doc to .wav)

And The Rockbox screendump

And the article on making a cable:

http://www.misticriver.com/iriver-audio-video/24707-usb-power-lead-pinout.html

I haven't made the input output cable yet, but was wondering if this is DC offset on left channel
or is it likely to sort itself out when I short the cradle detect pin to ground.

I read a thread on the cable, but it was not clear whether resistors or caps are needed and why.

Don't want to blow anything up!
Title: Re: H10 Pure
Post by: saratoga on February 28, 2010, 08:05:25 PM
Thanks for that,

I am getting a fluctuating signal on the left input about -78db
and the right input is steady at about -84.3db. This is without any cable connected
and line gain set at 0db. Tried turning off LCD, no difference.

Tried various sample rates 44.1, 48, 96 khz no difference.

You won't get a signal if you don't have a cable hooked up.  Not sure what you were expecting to see?
Title: Re: H10 Pure
Post by: petur on March 01, 2010, 03:34:48 AM
saratoga: I think he's wondering where the faint signal is coming from...
Title: Re: H10 Pure
Post by: Recording Guy on March 01, 2010, 05:38:23 AM
Yes I am trying to track down the left channel fluctuating signal.

Tested to see if Wolfsson had accidentally left the microphone on when in line mode.
Nope. This is not the case.

What I would like to see ideally is the left channel signal steady at around -84 db like its right signal. I normalised the H10 noise file to see what it is but I can't tell.


If anyone with an H10 could  go into record pause mode (line, pcm 44.1khz, no cable connected) and see if they get that fluctuating signal that would be great. Maybe my unit has a knackered ADC chip or something.

Thanks.
Title: Re: H10 Pure
Post by: saratoga on March 01, 2010, 06:32:09 PM
Yes I am trying to track down the left channel fluctuating signal.


You don't have anything connected.  Its just a floating input, which is floating around.  Hook up a source and see if theres actually a problem recording.
Title: Re: H10 Pure
Post by: Recording Guy on March 02, 2010, 03:27:08 AM
Ah, floating, okay cheers. bits are on order.

Interesting to note that gain will go down to -34.5db, could be handy for gear that puts out
+4db signal. Will let you know how it goes.

BTW this is Rockbox 3.5 latest, on Firmware v1.7ep MTP and everything is steady as a rock.
Scroll wheel works great, no lockups or shutdown freeze.
Title: Re: H10 Pure
Post by: Recording Guy on March 25, 2010, 06:34:24 PM
Well got the bits to make a cable for the H10, those pins are TINY, anyways managed it.

Had to wire up 8 wires (including earths for a stereo insert/return cable), and it seems that the
Cradle detect does need to be bridged with a bit of solder (next to it is an Earth pin luckily).

Still got the same noise on the left channel with the cable linked up. All permutations tried, changed the recording meter to show % instead of DB and the noise disappeared (from the display..looked encouraging)

Recorded though and the noise was still present on the wave file.

Do you think it must be a hardware thing (Wolfson? IRiver?)

It still seems to be "Floating" though the cable is well earthed...


I think this "blipping" noise was also reported on the Ipods as well. See Link Below:

http://www.rockbox.org/tracker/6989



EDIT:

Ok managed to do a line recording with the Iriver original software, only does 320kb MP3 max,
and I can confirm that the floating blipping signal is present on the left channel, so it isn't the (excellent) Rockbox software.


I know this isn't the Harware forum, but would anyone like to hazard a guess as to what it could be?

I would be prepared to risk "bricking" it in the interests of solving the problem if it only required a little bridging solder or something or a pin pulldown, in the interests of the Rockbox community that may like to record an ant squirting formic acid or a butterfly taking off.

-85 is fine but -78 may compromise some microphones for capturing very quiet sounds.


Title: Re: H10 Pure
Post by: Recording Guy on May 26, 2010, 12:18:56 PM
Just updating this thread for anyone making a cable.

the Cable Detect pin does not need to be bridged to earth if only using Rockbox.

If you boot up to original firmware, it will say "put the thing on the cradle" but since the Rockbox software
outclasses the original, can't see much point in using it.