TomWaterman
Well-known member
Hi folks,
I'm looking at the best way to implement mono summing in my monitor console design.
At this point I am undecided about needing a balanced or unbalanced summing network, still working on a few other things that determine this...anyway I was searching around and found the following:
http://www.rane.com/note109.html
While the Rane article is talking about crossovers for PA's the summing part is relevant.
While I am not so worried about cross-talk figure given as this is a stereo monitoring box and there is a reasonable amount of common-signal in stereo program material....I am worried about the following:
The low value input impedance of 1kOhm-ish.
I will probably be driving this network with some Forssell 992s and they don't have the drive capability so I'm worried about them crapping out so to speak.
The rane article mentions upping the values to improve crosstalk and input impedance which is cool and would solve that worry...however then its get sticky with regards to driving cable runs to the monitor amps etc. I don't want any HF droop due to large output Z.
So, should I up the values to improve input impedance / x-talk and then buffer the output of the box with a line driver to eliminate cable capacitance affecting the Freq response and be done with it??
Or should I go for a 2 input active summing amp? This would improve x-talk, and isolate the whole system from long cable run problems etc, no? but would it be worth it? I also prefer the fact the I shouldn't lose any level with the active device...
If I was going to do the active version, would it be best to go for something like 10k summing resistors or lower?
Also if I want to sum L+R and have the mono signal appear at both speaker outputs can I just parallel the out of the passive or active networks?
Any thoughts, suggestions etc?
Much appreciated
Cheers Tom
I'm looking at the best way to implement mono summing in my monitor console design.
At this point I am undecided about needing a balanced or unbalanced summing network, still working on a few other things that determine this...anyway I was searching around and found the following:
http://www.rane.com/note109.html
While the Rane article is talking about crossovers for PA's the summing part is relevant.
While I am not so worried about cross-talk figure given as this is a stereo monitoring box and there is a reasonable amount of common-signal in stereo program material....I am worried about the following:
The low value input impedance of 1kOhm-ish.
I will probably be driving this network with some Forssell 992s and they don't have the drive capability so I'm worried about them crapping out so to speak.
The rane article mentions upping the values to improve crosstalk and input impedance which is cool and would solve that worry...however then its get sticky with regards to driving cable runs to the monitor amps etc. I don't want any HF droop due to large output Z.
So, should I up the values to improve input impedance / x-talk and then buffer the output of the box with a line driver to eliminate cable capacitance affecting the Freq response and be done with it??
Or should I go for a 2 input active summing amp? This would improve x-talk, and isolate the whole system from long cable run problems etc, no? but would it be worth it? I also prefer the fact the I shouldn't lose any level with the active device...
If I was going to do the active version, would it be best to go for something like 10k summing resistors or lower?
Also if I want to sum L+R and have the mono signal appear at both speaker outputs can I just parallel the out of the passive or active networks?
Any thoughts, suggestions etc?
Much appreciated
Cheers Tom