H120: Do you like AGC?...

[Datman]

Used to work with hardware and/or software dynamics processors, I don't like very much the H120 AGC: I have tried the various presets, but it's very slow in the attack...
I.e., if I use it for interviews, it doesn't prevent clipping. It should reduce gain in a few milliseconds, then come back to the original gain in a few hundreds of milliseconds... Or not?

[Arni]

i´m taping concerts(stealth) and i never use(d) agc neither with my minidisc-device nor with the iriver-rockboxed.
i check the levels(starting low..so u get a fade-in effect) during the 1st song, which most propably is a rocker with high soundpressure levels and after having adopted the levels properly, i push the hold button and put my iriver into my pocket .
for meetings i use agc-speech.

[petur]

I only use AGC in the Safety (clip) mode, to make sure that *if* for some reason the SPL becomes a bit higher I don't end up with clipped recordings. It also eases the mind a bit - it stops me from checking levels again and again

Haven't tried the other modes.

[gloco]

I haven't touched AGC, I simply prefer to set the levels myself and be done with it.

[Arni]

hi,
just returned from the pearl jam concert and yes it turned out great.
used my iriver h120 with rockbox 20060923-build with MANUAL gain-control at +20dB with the battery box bass-roll-off at 95Hz.
tomorrow i will check if i need to raise the bass-frequencies a little.
thx for the greatest recorder and for rockbox the greatest OS for taping shows!
you rule!!!
 

[jhMikeS]

Don't know why the need to use software AGC when the codec chip in the H120 has AGC in hardware. I don't like the fact that it adjusts the global settings when changing gain either.

[petur]

Don't know why the need to use software AGC when the codec chip in the H120 has AGC in hardware. I don't like the fact that it adjusts the global settings when changing gain either.

1) the AGC in hardware is connected to the internal mic *only*, not line-in

2) as I've said a 1000 times, I don't use the software AGC as a real AGC, but rather as a clipping protection. I only use AGC in Safety mode. The reason behid it is simple. I set my levels conservative and don't touch my gear during the show. Sometimes I put it somewhere where I can't even reach for it during the show. AGC Safety has more than once helped to protect my recordings when the sound engineer turned out to have volume much higher than anticipated. There are no strict rules here so SPLs can differ a lot between shows.

That said, please don't remove or cripple AGC functionality. I find it quite reasonable that AGC changes the global settings. Else the next recording started in the same place would start off with bad levels again in stead of the correct ones of the previous recording.

[Mmmm]

I'm with Petur on this one

[mlind]

Used to work with hardware and/or software dynamics processors, I don't like very much the H120 AGC: I have tried the various presets, but it's very slow in the attack...
I.e., if I use it for interviews, it doesn't prevent clipping. It should reduce gain in a few milliseconds, then come back to the original gain in a few hundreds of milliseconds... Or not?

As a professional recording engineer I find the behaviour very much matches the term AGC. It should be slow.
You want a limiter or compressor.

I love the safety mode.

I agree that for random talking in a silent environment I would really like to have a fast compressor, but I dont.
But at least I have an AGC.  

[jhMikeS]

My real question was with some implementation particulars and the fact that it's in the hardware already. Why burn CPU cycles on it if the task can be delegated elsewhere on anything with a UDA1380?

But the X5 f.e. it _would_ need a software and prefererrably DSP approach (mic gain has only two levels).

I would like a compressor/hard limiter as well. Who knows, I might just make one at some point.

[petur]

My real question was with some implementation particulars and the fact that it's in the hardware already. Why burn CPU cycles on it if the task can be delegated elsewhere on anything with a UDA1380?

As I wrote today already: AFAIK, the UDA AGC is only available for (mono) internal mic, not line-in.

[jhMikeS]

Sorry. Neglected to read that. Been scrambling around a lot lately.

I can't see in the UDA1380 datasheet that the AGC block is only available to the mic. It's after analog front end and it just says that it _can_ be used for keeping mic at a constant level which is a bit ambiguous.

I wouldn't dream of removing or crippling the functionality so no worry. I'd only look into improving it and possibly freeing up CPU resources. The use of the global_settings recording level to store temporary gain levels is a bit odd IMO but changing that wouldn't cripple or affect it in any way.

I'm picking up an H120 soon so I'll be able to verify anything I change re: the UDA, SPDIF, and AGC (hw or sw) thoroughly myself.

[petur]

Mike,

Let me take back all I said earlier (should have re-read the datasheet)

the AGC in the UDA works indeed on both inputs, but it only operates on the decimator, so I don't think it's of any use.

I must have messed it up with the VGA/PGA difference bewteen mic and line-in in my poor memory.

Sorry for the confusion and nice to hear you're getting an h120

[jhMikeS]

...nice to hear you're getting an h120

I don't doubt that since I won't be bugging you to test iRiver stuff all the time!  
Should be here in a few days.  

[Arni]

i think i got the last available NEW iriver H140 yesterday from south korea!
its NEW with remote control and leather case etc.
235€ shipping included.

i copied the H120(my 1st iriver) harddisk content to the new H140´s harddisk made the firmware upgrade and voilá, all was fine and rockbox+my files were on my new H140!

am glad for having a 2nd of this awesome devices!

now all new h140 seem being sold on ebay....some refurbished h120 from australia are still available...got my h120 from this ebay seller in australia some weeks ago.

will use the h120 for taping shows and the h140 for recording from cable-radio at home.