PM1000 mix buss. Reccommend me something cool.

[honkyjonk]

Oops

Okay, let's try this:

If 33000/16=2062.5

Then we solve for X/12=2062.5
Which is 24.7K

Please tell me this is right. . . . . .

[Jim Williams]

The ACN topology also allow the console designer to switch channels on and off the
buss.

...whereas the passive design does not. If you remove channels, then there's less voltage drop in the summing network. The voltage on the buss will be higher.

This is why consoles "back ground" unused/unassigned buss resistors. That also helps control capacitive crosstalk.

[The Scum]

This is why consoles "back ground" unused/unassigned buss resistors. That also helps control capacitive crosstalk.

And if the source impedance is constant, it holds the GBW of the summing amp at the same place. So the sound doesn't change as channls get on/off the buss.

Oops

Okay, let's try this:

If 33000/16=2062.5

Then we solve for X/12=2062.5
Which is 24.7K

Please tell me this is right. . . . . .

Um, not quite.

That gives is a bus with 12 channels, that has the same source impedance as one fed by 16 33k Rs. But the attenuation (and makeup gain) is the same as for any bus with 12 equal value resistors. The exact value doesn't matter, just the ratio of the feed resistor the but buss impedance.

The problem we're solving is different. You've been proposing taking a buss that had 16 channels, and removing 12 of them. So we need to calculate the equivalent value of the resistors that have gone missing.

Product over sum is usually easier, but 33K ^ 12 blows up on my computer...very big number. So we'll need to use inverse sums:

R = 1/(12 * (1/33k))
= 2.75 K

[honkyjonk]

Ah jeez,

Thanks Scum. That looks like a little simpler version of the equation on that page that you linked me? I wasn't sure what to plug in where, or what "tot" was.

So, I would plug in an 8 where the 12 is obviously for the 8 channel switch?

Really patting myself on the back for figuring this one out (sarcastic sentiment implied)

[honkyjonk]

Just reporting back with some success (I think) Just gave the first 4 channel version a quick test through the mono program buss. Sounds a lot better.

Thanks so much Scum.

Only question I have left (hope it's not too much to ask) is how much to increase a couple caps in the master strip.

Here's the link again for convenience.
http://www.gearslutz.com/board/attachme ... beled-.jpg

Looks like C1. But should I go as high as the input strips? (.1uF to 3.3uF is a big increase)

C7? Maybe?

And C12 appears to be the equivelant of C37 in the input strips, which commonly get's increased from 33uF to upwards of 220 to 333uF.

In the master strip, it's a 100uF cap. I have extra 330uF's.

??