hey everyone. sorry if this has been done before, ive tried searching and not coming up with much helpful. I come from a studio background but never needed to consider much of this, working a lot in the box and only using outboard gear for colour etc.
I am trying to figure out the gain structure for my rig, and am a bit OCD once something gets in my head, often its unnecessary crap but something i need to sort out!
essentially i am running my gear as follows
sources: turntables, CDJ --> allen and heath s2 mixer --> ras efx reggae pre --> i-nstruments VU meter (monitoring) --> powersoft x8.
now, whats getting me stuck is the differences in db measuring. I shall go through some points one by one...
allen and health s2: output from xlr balanced is the standard "professional" +4dBu, all very well. On the back there are some recessed pots for attenuation on channel gains, but also it has a "master output limiter" whos settings have thresholds ranging from +6 to +18dBu.... The master level indicators go from -20 to +10! (no mention of what units) with the sensible suggestion to keep average level at 0, with peaks up to, but no higher than +6 (+10 is the clip red light)
so number one question is wtf are these units... secondly, if the main output is +4dBu, what does it mean to have a limiter threshold set at +18dBu...(seemingly higher than the output level...does this make sense to anyone???)
now, from here i run into the RASEFX pre, 12 o'clock is basically "pass through" ie no gain added, however EQing and so on will add some gain. Here (at home) i usually attenuate the music level by keeping that knob at 11 o'clock to allow for flexing the EQs and so on. all well and good.
This then sends an out to the i-nstruments VU meter, which is a copy of the Dorrough rack mount thing. it has 0db at the top of the yellow meters, after which its red... doesnt say dBu, just dB. its a studio centric device, so i assume this is just studio 0dB (probably +4dBu professional as when the s2 meters are at zero w small peaks, its also at zero w small peaks)
now, the powersoft x8 default setting on inputs in armonia have two metering options, dBFS and dBu. ive not really messed with these and just used the age old green light orange light red light as a metering to know whats going on, but, yeah, ocd....soooo
it seems that by default on the input meters, they have 0dBfs set at 24dbU (and it says its max input acceptance is 27dBu...?)
from my reading, it seems in order to maintain a decent amount of headroom for peaks, 18to 20db of room is about standard, and therefore that that the RMS average should be -20dbFS, or +4dBu (0dBfs - 20dB = -20dBFS ~OR~ 24dBu - 20dB = +4dBU...)
then if the max tolerance without clipping the input is +27dbu...are they just setting the 0 dbfs (which cannot be exceeded?) to 24 for safety?
1. is this thinking even right? 2. does this then mean that driving this amp to max will occur when my levels as shown on my i-nstruments meter are at 0 (signifying the S2/RAS poutput is +4dBU??) 3. Is there some untapped power or room for more level here... 4. im sure im just getting confused with it all...id love someone to be able to explain this like they are talking to a ten year old!
thanks
J
|