Re: GAIN STRUCTURE

[van Sinn <vansinn@post.cybercity.dk>]

See my comments between lines below..

J Johans wrote:
> hard to work through without looking at it-
> one thing i would suggest as this has helped me in the past...
> 
> find the manual on every piece of gear and determine whether the 

Exactly!  Knowing which levels, i.e. instrument- or line level, for each 
input and output is essential.

I don't know all the gear referred..  It's possible all levels match 
just fine, but also possible that some instrument-level input is 
connected to a lineout level.
Sometimes this will work, provided the input level control has enough 
adjustment range to handle this - and provided out- and input impedances 
don't mismatch too much.

Impedance mismatch isn't likely the problem with said gear.
Typically, output impedances are relatively low and inputs are high, 
which will work fine; it's more the levels that matters.


> inputs/outputs are balanced or unbalanced (in your terms, stereo or mono)
> im still learning, but what balanced cables do is reduce noise, 
> especially over long cable runs
> they do this by sending an additional signal that is 180 degrees out of 
> phase-
> so your tip and ring of a balanced connection are the same signal.... 
> but they invert the waveform on the ring... thus canceling out any noise 
> induced along the way-
> 
> i have learned.... if you are connecting an unbalanced output to an 
> unbalanced input... use a mono cable.... rather if both input and output 
> are balanced ...ie.. TRS.... use a stereo cable-
> 
> in theory and in research....it honestly should make no difference...  
> but my experience shows otherwise
> 
> the other big issue is the +4 -10 ... im not familiar with the gear you 
> are using, so its hard for me to determine what each piece does ... but 
> when the +4/-10 comes into play.... honestly just try both ways to see 
> which one has less noise-
> ...snipped...

Agreed.  this is the in/out level differences, as said above.

> froshizzle
> 
> ------------------------------------------------------------------------
> Date: Sun, 8 Mar 2009 08:56:03 +0100
> Subject: GAIN STRUCTURE
> From: mark@markfrancombe.com
> To: Loopers-Delight@loopers-delight.com
> 
> OK,, technical people...
> 
> I have never been very good at technical stuff, despite having enough 
> gear to launch a shuttle.
> So now i want a technical 101 type course in getting a good gain 
> structure in my gear.
> ...snipped...
 >
 > Now, for some reason,  the 2 EDP's are completely different sounding
 > (old one is kinda muddy and bassy, loses top), and the thing is that I
 > just cant get a good level without distortion on the loop (too high
 > level going in) or too low and hissy.

Here you need to isolate the problem, i.e. run one EDP at a time in the 
same configuration, to determine if one might have a problem.
If both works/sounds the same in the same setup, it's not the EDP's, but 
your rigging hookup.


> So now I have SO MANY input level controls on my system, something is 
> causing distortion I dont know how to start... heres the signal chain.
> 
>    1.  From guitar (first a few stomps) First level control VORTEX
>    2. Second level control MIXER INPUT (two levels on switch +4 or -10)
>       + track level. (up to here is ok, I can hear that my guitar is
>       clean and undistorted, and has some headroom when I hit the thing
>       (Vortex lights up red only on REALLY loud hits)
>    3. Third level control, SEND level (both track sens and overall SENDS
>       level control)
>    4. Fourth level control EDP input level
>    5. Fifth level control EFFECT input level control (altho there is
>       really no input level control on the red sound federation, just a
>       gain adjust in one of the menus)
>    6. and SIXTH input level control MIXER INPUT (two levels on switch +4
>       or -10) + track level. (this is where EDPs + effects are returned
>       to mixer)
> 
> 
> So what is a good routine in figuring out a gain stucture, that is both 
> loud and clean?... and what should I set the mixer level switches to... 
> loud or quiet? (+4 or -10)

I'd suggest:
. check the manuals WRT in/out levels and type of cabling
. verify your intended hookups match above findings
. turn all inputs down, and start setting input level on first device
. then move on through the chain - keeping all send/return loops muted
. when the direct chain works, move one to set levels in the loops



Some generally useful info on building rigs are emerging on 
http://www.adadepot.com/forums/
We're right about editing a number of good threads to be merged into 
some howto's/guidelines.  They'll likely be found in the Technical 
section or the FAQ section.  Give us a bit'o'time ;)

-- 
rgds,
van Sinn