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Post by jcoutu1 on Apr 8, 2014 8:42:29 GMT -6
Example:
Let's say that i have a summing box that has inserts on every channel such as an SPL Mix Dream. Is there a difference between coming out of the converter, into a compressor, then into the summing vs. converter, into summing with the compressor on an insert? Is the only advantage of the insert that I get a bypass switch with the insert? Are there any signal flow problems by not having an insert for the hardware (other than losing the bypass switch)?
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Post by tonycamphd on Apr 8, 2014 8:54:58 GMT -6
if i understand your question correctly, i would say, as long as you have hard bypass in your compressors, IMO no need for the insert on the analog summing. I assume your considering passive summing? with a couple of missing links for make up gain, thats an awesome idea.
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Post by jcoutu1 on Apr 8, 2014 9:02:17 GMT -6
I'm really happy with my Midas console, but my space is really cramped so I'm looking into a few different rack mixers/summing solutions. The other issue that I'm running into is recall time. I jump back and forth between recording and mixing and different projects and such, and while I love having eq on every channel of my board, I just don't have enough time to be dealing with the recall of the whole board. A smaller footprint with quicker recall might be a better solution for my current situation even though it's not my ideal setup.
I don't really dig the idea of analogue loops for hardware inserts or whatever, so summing with the ability to use some outboard might be the move. Fat Bustard is at the top of my list right now, but I'm also looking into an API DSM system, Chandler Mini Mixer, and maybe a few other units.
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Post by sll on Apr 8, 2014 9:07:25 GMT -6
There really shouldn't be any signal flow problems putting the gear ahead of the summing box instead of at the insert. The only difference with an insert is you have the gear after another set of amplification within the summing mixer. In many consoles, the insert has a send driver and return buffer amplification stage. I doubt the difference has any sonic impact, although you might have a cleaner/shorter signal path not using the inserts depending on the design.
I see advantages of using inserts when you can switch them on and off, and are able to switch pre or post EQ like on large consoles.
In short, probably no audible difference using them or not in a summing box. Whatever is most convenient in setup and workflow.
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Post by svart on Apr 10, 2014 7:39:00 GMT -6
Yes, there can be issues, which may or may not be serious.
Modern converter outputs usually have medium impedances in the 100-600R range, intended to be used with modern Line-In impedance(5k-10K ohms.) If they see a lower impedance (600R) from some vintage line-in device, you *might* have issues due to the current drive abilities of the converter output(current starvation). Some might be able to drive 600R, some might not, and still some might have frequency/distortion issues as they run out of current to drive the load. You won't know which you'll have, and they might be random, and you might have an issue you can't hear easily so you think everything is fine..
Most summing boxes are passive devices until they reach the gain makeup amplifiers. These boxes use series resistors to further drop the current so that the device driving the input doesn't have to work very hard while fighting currents from other channels. If one of these boxes were to have an insert in the passive sections, then the insert would be all messed up impedance wise. I doubt any designers would be foolish enough to try this, but with the rise of half-baked one man operations stealing ideas from internet forums and cobbling them together to make a quick profit, then I wouldn't be surprised if there were some around..
On the other hand, they could have two amplifiers in series in the output section, one for gain and one for buffering, so that the passive summing section sees a static high impedance and the buffering amp is used to convert whatever it sees coming back from the insert into a low impedance for driving the outputs. That's the only sensible way of doing this with a passive input and summing.
The thing I would like to see is each input to the summing box being buffered and an insert placed there between two amps. Putting the gain up front, before the resistor summing, reduces noise figure. Gaining up after summing is always going to give you more noise, with the noise addition equal to whatever the summing loss is. This would use a lot of dual or quad opamps, which would eat into the crazy profits summing boxes make for their manufacturers. Why does a bank of resistors and a couple opamps cost so much, anyway??
Anyway, none of this gets into other issues, like if the box has a "passive" summing amp, or if it's "virtual earth" summing amp.. The passive summing amp can see changes in level as channels are added or taken away, while the virtual earth summing amp design does not. Adding a different impedance to the input of a passive input with a passive makeup amp throws even more wrenches into the mix.. (pun intended).
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