Insufficient level in H1xx recording

[Muse]

I have an iRiver H120 (with 30 GB HD) and an H140. Currently I'm making WAV recordings with both, one to WAV using the internal mic and the other to WAV (which I post process to MP3) using line-in analog input. I'm using a recent version of Rockbox.

The WAV recordings made from analog line-in are coming out with insufficient volume when processed to MP3s and played in my portable MP3 players (Sansa Sandisk m250s with the inefficient Etymotics ER4S earbuds). Post processing with Audacity or MP3Gain is a PITA and I'm not certain how to do that properly in any case. How can I get the H1xx to record with adequate levels to begin with? When setting the H1xx to record I can increase the evident Gain before starting the recording. I boosted it from - 1 db to 8 db and am not sure it was an improvement.     What am I doing wrong? Should I boost it to 17 db??? TIA...

[Llorean]

Please read our forum guidelines. You posted this in the installation section, and it clearly has nothing at all to do with installing Rockbox.

Are you sure the source you're recording from is outputting at a line level?

[Muse]

Please read our forum guidelines. You posted this in the installation section, and it clearly has nothing at all to do with installing Rockbox.

Are you sure the source you're recording from is outputting at a line level?

I'm sorry, I didn't notice. Not a good excuse, but it's the first time I've visited these forums in many months. I wasn't familiar with the structure and didn't notice where I was. Again, I apologize, and thank you for moving the thread where it belongs.

I'm not certain about the levels being supplied. I will mention that to the station engineer. This is a radio station and it's in the air studio.

Thanks for your help.

[petur]

if you increase gain, you should get better levels. You can go up to +48dB but I advise against that, anything above ++15 to +20dB will start to give noticeable noise (test for yourself)

If +15dB doesn't give enough level, your source signal is too weak. Get a pre-amp or change the output level of the source.

[Muse]

Thank you. My recording made 2 days ago was +8 db, and it really wasn't nearly enough. I'll try +15 db next time. I do have a preamp. It's a headphone amplifier that I bought when I got a pair of Etymotics ER4S earbuds, notoriously inefficient (but otherwise in many ways excellent). When I bought the Etymotics I did research and saw that a great many buyers (maybe the great majority) were buying a headphone amplifier for them, and I did so, anticipating I would need it. As it turned out, I have gotten sufficient listening volume in my portable devices (from cassette to iRiver iMP-350 CD/MP3 to iRiver H1xx to Sandisk m250), and have used the preamplifier almost not at all. It is battery operated (AC adaptor is supported and I have used that a bit).

The headphone amplifier I have is an Airhead "Headphone Amplifier and Audio Image Processor." If it works electronically adequately for the purpose, the size and connections are nearly optimal. A stereo cable was supplied with miniplugs on both ends and it has a volume control. My only problem with it is knowing where to have that volume control. It's entirely analog so I can't have a standard setting for it.

I think my best bet if I need higher levels on the line-in is to get the engineer to boost the levels. He's an audio engineer (well, I think he is, not sure) experienced and although always a busy guy with more on his plate than he can deal with in the short term, he can probably deal with that. I'm not the only person who wants to make in studio recordings from that line-out stereo feed.

[petur]

microphones and line-in are not headphones, so the sound may not be perfect.

Getting better line-in levels is your best bet. Make sure they do not get too hot as that would damage the input circuits.

[Muse]

Unless I'm missing something it appears that Rockbox is such that AGC backs off when the levels get into clipping range and don't rebound! That appears to be the reason my levels were insufficient. I looked it up in the manual. My workaround is to turn off AGC. I set my levels using the VU meters in the studio, set the level on the H130 and leave it. It's on me to get my levels right during the entire recording, which is about 3 hours. My levels were a little low last week at 3 db. I'll set them at 6 db on Tuesday and see how it comes out.

[petur]

Unless I'm missing something it appears that Rockbox is such that AGC backs off when the levels get into clipping range and don't rebound!

That sounds like AGC SAFETY to me... that is the only AGC mode that only decreases gain, all the others also increase.
Anyway, if you want to set levels by hand and keep them like that, you better turn off AGC completely