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Old 21st December 2013, 10:54 AM   #1
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Default Middle Controls

Hello to all!

In the book Small Signal Audio Design by Douglas Self, chapter 10, page 271, where the author talks about the middle control, he wrote:
"It must be said at once that middle controls, while useful in mixers, are of very little value in a preamplifier. If the middle frequency is fixed, then the chances that this frequency and its associated Q correspond with room shortcomings or loudspeaker problems are remote in the extreme."
Could someone please explain why this is?
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Old 22nd December 2013, 04:38 PM   #2
rsavas is offline rsavas  Canada
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Basically is saying that the filter center frequency is fixed thus it has limited use because it will add a peak or droop at only one frequency and bandwidth(Q). Since it is in the critical voice region, not having variable BW/Q is not very useful and will affect the voice dramatically. You are better off just having bass and treble controls.
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Old 23rd December 2013, 10:08 AM   #3
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If the control is the same and with the same limitations, why it is useful in a mixer and not in a preamplifier?
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Old 11th January 2014, 08:04 PM   #4
Jsixis is offline Jsixis  United States
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Quote:
Originally Posted by paulopca View Post
Hello to all!

In the book Small Signal Audio Design by Douglas Self, chapter 10, page 271, where the author talks about the middle control, he wrote:
"It must be said at once that middle controls, while useful in mixers, are of very little value in a preamplifier. If the middle frequency is fixed, then the chances that this frequency and its associated Q correspond with room shortcomings or loudspeaker problems are remote in the extreme."
Could someone please explain why this is?
He is saying he has no clue as to why someone would want that.
In my case I find the mids can be too loud on some recordings and I would rather cut them then boost the highs and lows.
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Old 11th January 2014, 09:31 PM   #5
sreten is online now sreten  United Kingdom
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Quote:
Originally Posted by paulopca View Post
If the control is the same and with the same limitations,
why it is useful in a mixer and not in a preamplifier?
Hi,

It might be useful occasionally on each channel of a mixer,
but is useless in a home HiFi set up as a general control.

rgds, sreten.
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Old 11th January 2014, 09:38 PM   #6
rongon is offline rongon  United States
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Quote:
Originally Posted by paulopca View Post
If the control is the same and with the same limitations, why it is useful in a mixer and not in a preamplifier?
In live sound, you're not always as interested in 'high fidelity' as in getting a pleasing sound in the room, with limited tools. So for instance, if you have a 'honky' sounding microphone, or a tendency for feedback around 800Hz, it's helpful to have a MID control to tone down the accentuated response in that region.

Let's say you're close-miking the snare drum in a drumkit (like in a rock band), and there's a nasty resonance at about 800Hz. While it's best to place the microphone in a better location relative to the sound source (snare drum), sometimes that's just not possible. So having a MID control that you can use to attenuate that frequency range is better than having nothing at all.

A mixing console in a recording studio or major concert venue will have far more complex EQ than simple bass-mid-treble controls, so that doesn't apply to this conversation (as I see it).

I hope that helps.
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Old 11th January 2014, 09:51 PM   #7
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Doug Self is very sharp at most things related to audio engineering. He may be one of the best these days in many areas. Tone controls have been rather controversial in recent years. Many think they are always bad. Many ridiculously expensive preamps are nothing more than an input selector switch and a volume control, with no tonal adjustment at all. Others have gone to the opposite extreme building preamps that effectively have entire graphic or parametric equalizers. I've been eating and breathing audio engineering sine the mid 60's, and have my own opinion.

I prefer a four section Baxandall tone control circuit; Lo, Lo-Mid, Hi-Mid and Hi. I've optimized it for creating a reverse Fletcher-Munson curve (loudness compensation), but with enough flexibility to work well with most other typical problems as well (room acoustics, speaker dispersion issues, bad recording mix, etc.). After living with it for decades (first in '83), I'm very happy with it. I consider it one of the most important parts of a good sound system.

There are those who strive for what they are taught to believe is technical accuracy, and there are those who just go for what sounds best. Guess who wins?
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Old 13th January 2014, 11:45 PM   #8
Jsixis is offline Jsixis  United States
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I occasionally run sound for small bands in really small bars. Bands usually bring concert sized gear. I find the sweepable mid gives me the ability to find their voice and get it out in front of the instruments.
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Old 13th January 2014, 11:53 PM   #9
Jsixis is offline Jsixis  United States
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Nice website Bob, Nice to see someone else who has used felt around the outside of speakers
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