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Author Topic: Passive Monitoring for DAW  (Read 3157 times)

Dennis Allen Cupp

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Passive Monitoring for DAW
« on: April 21, 2004, 04:41:43 pm »

Ok Group.
about a year ago i bought the Coleman TB4. There was nothing else like it on the planet. I spent time talking with the the designer of the box (Glenn) and he was very informative about all the strides he went through to make it. At the time there was NO competition.

Fast Forwad a year.....

Everyone is making these boxes. Mackie, Presonus...you name it.

Here is my question. Coleman boasted of it being totally passive AND it had a 300.00 volume knob that would please the staunchest of Audiophiles. He used the SSL masterfader until they discontinued it, so he found this swedish company that made this fancy Audiophile knob that costs HIM 300.00 bux each.
If the new Presonus and Mackie are BOTH passive systems.
HOW DIFFERENT would they be than this 1000.00+ coleman box?
The Presonus has MANY more features than my TB4 that i could certianly use. Is the knob "ALL THAT" in a passive system. Would i notice a big difference.
I realise its one of the most important parts of my DAW Universe, so i dont want to upset the apple cart by replacing it and thus creating a less optimal mixing enviroment. The coleman is missing some thing is could use.

Would a lesser volume knob in a passive monitoring system be a huge difference?

Dennis
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bblackwood

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Re: Passive Monitoring for DAW
« Reply #1 on: April 21, 2004, 05:10:25 pm »

Hi Dennis. The answer is yes, the expensive potentiometer is better built. What really differentiates the great pts from the ho-hum ones is the ability to track accurately (channel to channel) at the extremes of the pots throw (low level and high). You pay for accurate channel balance...
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Brad Blackwood
euphonic masters

grock5

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Re: Passive Monitoring for DAW
« Reply #2 on: April 21, 2004, 07:50:27 pm »

IIIRC, I think Coleman uses the DACT attenuator which is a stepped, series attenuator with a fairly high impedance.

This presents two possible problems:

1. Series attenuation: as you increase attenuation, you increase the amount of resistors in the signal path, which can lead to coloration of the signal.

2. High Impedance: a passive attenuator with a Hi-Z has a strong potential to fuck with (reduce) the high frequencies passing through it.

To get an idea of what such a device can do to your signal, try out this calculator on the Mogami Website. Try an input value of 20000 Ohms, over 10 meters of cable. For output impedance (your attenuator) try a value of 25000 then 2500 and compare the graphs.

However, when compared to a rotary potentiometer like the cheaper boxes are using, the dact is going to perform better.
...But in a passive environment, a custom spec'd, lower impedance, Bridged T from Shallco will kick it's ass.

-- Gary
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dcollins

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Re: Passive Monitoring for DAW
« Reply #3 on: April 24, 2004, 04:00:06 am »

Quote:



To get an idea of what such a device can do to your signal, try out this calculator on the Mogami Website. Try an input value of 20000 Ohms, over 10 meters of cable. For output impedance (your attenuator) try a value of 25000 then 2500 and compare the graphs.



I tried Zout 2500, Zin 47000, 20pf/ft, 25R/1000ft.  Five meters long.  Looks like a line!  I must find something more exotic.

DC

grock5

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Re: Passive Monitoring for DAW
« Reply #4 on: April 24, 2004, 04:56:53 am »

[quote title=dcollins wrote on Sat, 24 April 2004 04:00]
Quote:



I tried Zout 2500, Zin 47000, 20pf/ft, 25R/1000ft.  Five meters long.  Looks like a line!  I must find something more exotic.

DC


Do you have a cedar "sleepy time" case for them??
Electrons seem to like that shit.

-- Gary


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