Electronics > Beginners
Audio Conventions - Levels and Meters
(1/4) > >>
ed_reardon:
Hello all,

Starting out on a little project, wonder if anybody can help here, as I'm getting nowhere fast talking to experts,  I must be being obtuse! I'm looking at building a small mixing desk and audio recorder. 

The idea is to have selectable inputs between microphones with conventional TRS connectors as well as powered XLR inputs.  Can anybody clarify which are the conventional nominal levels used between the two connectors and types.

Also for metering on a mixing console,  do the conventional slider controls with the 'chasing' LEDs measure a rectified average,  peak or VU because again, I can't really get a clear answer.  I've had many 'dunnos' but to me there's quite separate concepts!

Sorry if these are really daft questions, but audio is something I've never touched.  It's only for a little project, I know I could buy something cheap from eBay, but where's the experience and challenge in that!?

Cheers,
Ed



Harb:
You will do very well to nail down a standard in Audio........ There are so many "Standards" depending on who you talk to.....

I am in the TV industry, so the only one we are interested in is +4dBm (600 Ohms) after all is said and done....it used to be +8 a few years ago, but +4 is now the accepted level....
Having said that, with the acceptance of HD things have become different again and measuring much more complex.
ed_reardon:

--- Quote from: Harb on May 27, 2018, 09:29:01 am ---You will do very well to nail down a standard in Audio........ There are so many "Standards" depending on who you talk to.....

I am in the TV industry, so the only one we are interested in is +4dBm (600 Ohms)....it used to be +8 a few years ago, but +4 is now the accepted level....
Having said that, with the acceptance of HD things have become different again and measuring much more complex.

--- End quote ---

Thank you Harb,  yes,  I'm starting to realise that nobody seems entirely sure what's-what!
Harb:
Audio is awful.......

Domestic gear is all over the place.......
dmills:
Mic levels can be all over the place (apart from anything else depending on where you PUT the things!), which is why there is usually a mic gain control with at least a 40dB range (and often a 20dB pad switch as well), maximum gain wants to be somewhere around 60dB for a general purpose desk.

Channel strip meters should generally be peak responding as your major use here to to make sure you are not clipping (These meters should be pre-fader), a clip indicator sampling several points in the strip is also a good idea.

Output meters very much depend on what you are intending to drive, PPM is traditional on EU broadcast desks, but if you are driving some sort of digital chain a very fast attack DPM style affair may be more useful, or if working in a loundness normalised environment a EBU style BS1770 job may be appropriate.

Nominal levels at line outputs are usually a few volts, but often have at least 20dB of headroom over whatever nominal means.

Were I doing this project I would start by obtaining a copy of Doug Selfs "Small signal audio design" book, well worth the investment. Focal press also have an entire book on audio metering that may be relevant.

Regards, Dan.
Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod