Topic: So ... recording with the iRiver. finally feasable?

[petur]

I've checked many, many info overhere and on the Rockbox-forum, but can't any info about the gain-settings on a Rockboxed H120 while recording analog line in without any pre-amp.

What is there to know more about the gain?

The audio chip has an 'analog gain' and 'decimator gain'. The first one does big steps (2 or 3 dB depending on internal mic or line-in), the second one does 0.5 dB steps.
Rockbox does 0.5 dB steps over the whole range and breaks the set value down into as much analog gain + the rest from the decimator.

The decimator acts on the full ADC bit data before it's downconverted to 16bit, so it *is* usefull.

[MadMaster]

What is there to know more about the gain?

Maybe I wasn't clear enough, but what I'm searching for is some reference, based on others experiences, about ACG gain-settings on the Rockboxed H120 while recording analog in.
For example, do people leave the settings for what it is (0 dB) or do people add/lower gain for both channels?

I know it depends on the circumstances that you have while recording, but that's why I asked for info for all kind of venues, type of concerts etc.

As a newbie with the Rockbox H120 it would be nice to have some kind of reference, before screwing up your recording because of bad settings...
While I'm mostly as stealth as could be, I'm not able to check the display during recording for clipping. I would rather like to be on the safe side with my settings before hitting the record-button...

[TideBleach]

What is there to know more about the gain?

Maybe I wasn't clear enough, but what I'm searching for is some reference, based on others experiences, about ACG gain-settings on the Rockboxed H120 while recording analog in.
For example, do people leave the settings for what it is (0 dB) or do people add/lower gain for both channels?

I know it depends on the circumstances that you have while recording, but that's why I asked for info for all kind of venues, type of concerts etc.

As a newbie with the Rockbox H120 it would be nice to have some kind of reference, before screwing up your recording because of bad settings...
While I'm mostly as stealth as could be, I'm not able to check the display during recording for clipping. I would rather like to be on the safe side with my settings before hitting the record-button...

i was just at a small club a few days ago using my sp-bmc-2's and battery box and my h120 and for my level setting i was using 7.5. ive had to go up to 10 or 15 at an outdoor show before. so for small venues my setting range from 7.5 to 12 and outdoor ive done 10-15 it all depends on the show really. most of these were really loud metal shows. i hope this gives you an idea. o yeah the h120 goes up to 24 analog gain before switching to digital gain.

TideBleach

[petur]

In the rockbox forum, there's a Recording Enhancement Pack offered (official sources plus a number of patches).
That build includes an AGC. Its default setting is Saferty, which does the following: If levels become too hot (above -3dB I think) it decreases gain by 0.5dB.

For stealth recording this is very nice. Just take a guess at initial gain and know that the AGC will correct if you applied too much gain.
The AGC works fairly slow, so I wouldn't call it a true AGC but more a clipping safety feature.

Gain settings depend on the mics and pre-amp, so it's hard to say.
I would use as much gain on the pre-amp as possible and as close to zero as possible on the iriver. When using the AGC feature, leave some headroom (10dB ?) so it can lower gain if the show gets louder (some rock shows seem to do that near the end)

[MadMaster]

TideBleach & Petur, thanks for the answers.

I wil check that Recording Enhancement Package, but, like I said, I like to be on the safe side with my initial settings so that the recording levels are continious all the time.
A AGC clip-detection/correction is nice, but will decrease the recording level (although it is not that much) during the recording.
And as I've always been told: "Keep your fingers off the buttons during recording!"  I don't think it's something for me to use.

[treespine]

Anyone have a link to the Recoding Enhancement Pack.  I looked on the forums, but I am a newb.  Is this a plugin, a patch or firmware upgrade?

[whatboutbob]

Anyone have a link to the Recoding Enhancement Pack.  I looked on the forums, but I am a newb.  Is this a plugin, a patch or firmware upgrade?

http://forums.rockbox.org/index.php?topic=2513.0

[treespine]

Thanks , im installing this Mmmm guys build now. 

Anyone know if the 3.7v of power that is always fed to the line in of the iRiver can be damaging to preamps.  Specifically the SP-PREAMP?

[hyperplane]

What is there to know more about the gain?

The audio chip has an 'analog gain' and 'decimator gain'. The first one does big steps (2 or 3 dB depending on internal mic or line-in), the second one does 0.5 dB steps.
Rockbox does 0.5 dB steps over the whole range and breaks the set value down into as much analog gain + the rest from the decimator.

The decimator acts on the full ADC bit data before it's downconverted to 16bit, so it *is* usefull.

+T to you, petur. I thank you for the explanation on the decimator stage of the gain being useful. I was unaware of this before reading your post.

[TideBleach]

Thanks , im installing this Mmmm guys build now. 

Anyone know if the 3.7v of power that is always fed to the line in of the iRiver can be damaging to preamps.  Specifically the SP-PREAMP?

i wouldnt think so people use them on minidiscs mic in and that gives off plug in power even though line in would be best. im pretty sure the preamps have a resistor/or something to block incoming voltage that would be my guess.

[petur]

Anyone know if the 3.7v of power that is always fed to the line in of the iRiver can be damaging to preamps.  Specifically the SP-PREAMP?

My iriver h340 always puts out around 3.7V on the line-in plug (ok, depends on the battery voltage), and afaik the audio circuit of the h1x0 series is about the same. It's a very simple circuit, I think the schematic is available somewhere in the rockbox wiki.

[treespine]

Thats cool, but is seems like a waste of power and it could cause problems for the gear being plugged into that jack. Too bad you can't turn that power off. 

FWIW I have no idea what I am talking about

[thegreatgumbino]

Thats cool, but is seems like a waste of power and it could cause problems for the gear being plugged into that jack. Too bad you can't turn that power off. 

FWIW I have no idea what I am talking about

That's f*****g hilarious!  Thanks for the laugh!  +T

[treespine]