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strange volume trouble
Using a M-audio Fasttrack pro USB sound input device.
Put my mic in front of a speaker sending out a testtone.
My input gain is a knob that rotates 270 degrees (or something)
Fully open i get sound. Testtone is set so i record at -3 dB
Turn down the knob by 15 degrees, and it’s SILENT.
Am i right assuming that the potentiometer used in this unit
is logarithmic where it should be lineair, or vice versa?
This can’t be good, i’m used to lineair faders….Or am i missing something else?
Bouke
https://www.videotoolshed.com/
smart tools for video pros -
14 Replies
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If you can measure full-open as “-3dB”, then how about giving us a number for the other case. “silent” isn’t a very objective measurement. How far can you turn it to get to -12? -24?
Note also that input trim (gain) controls are not intended to be as “linear” as the mixing controls. Their primary purpose is to allow a very wide range of input amplitudes to be accomodated.
I wouldn’t say categorically that your symptoms describe an actual problem. But there MAY be a problem, but not enough info.
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Richard,
Silent in this case means silent. No sound, nothing, nada.
– infiniti DB, or digital sample values of 0.
IOW, as loud as no mic attached…As for your statements that trim controls are not always ment to be lineair, that’s indeed new to me. I haen’t seen it on any mixer i’ve used, and i can’t understand in what situation it could be handy.
Humans think/move close to linear, not to log.Besides, i can’t believe it was intentionally on this thing, sicne it’s being sold as a mic pre-amp. And having just a few degrees making the difference between overmodulating and no recording at all ain’t the way i can work…
So i was hoping for something else i’ve missed.
Bouke
https://www.videotoolshed.com/
smart tools for video pros -
Can you try the source into some other preamp that you are familiar with? It has the symptoms of a very low-level source. I have seen some preamps that pump in a whole lotta’ gain in the last few degrees of rotation of the trim pot. Generally with those kinds of preamps you don’t really want to be operating in that region of the adjustment.
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Very funny.
I’ve tried. Believe me.Let me introduce myself. I run a high-end video post production facility, and i write (custom) software for the audio/visual/film industry.
It’s not that i don’t know what could happen, its just that i cannot understand that anyone is putting out a piece of crap this unit is.
M-audio is Avid. I have used Avid products over more than a decade, and i’ve never seen something as bad as this.My guess was that i’ve overlooked something, but the more i dive into it, the more i’m convinced that this is either bad desing or bad manufacturing.
Going to a VAR wednesday to get a decent piece of gear.
(what i’m doing is making a software based BWF recorder with LTC out, and i liked the front knobs of the Fasttrack, so i bought one.)
Bouke
https://www.videotoolshed.com/
smart tools for video pros -
see below
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[Bouke Vahl] “Humans think/move close to linear, not to log. “
Not true.
The ‘log pot’ is used as the volume control in audio amplifiers, where it is also called an “audio taper pot”, because the amplitude response of the human ear is also logarithmic. It ensures that, on a volume control marked 0 to 10, for example, a setting of 5 sounds half as loud as a setting of 10.
KB
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Yes.
using log potmeters to make mathematical correct log values into lineair values that humans understand.
that is exactly what i was saying.Now where does the ‘not true’fit in?
Bouke
https://www.videotoolshed.com/
smart tools for video pros -
[Bouke Vahl] “Humans think/move close to linear, not to log.”
KB
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Mr. Brown claimed that Mr. Vahl’s statement was “Not true.” And then he proceeded to demonstrate exactly why Mr. Vahl IS correct. Log pots are used to take log phenomenon and “linearize” them so that they are easier to manage by humans.
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[Richard Crowley] “Mr. Brown claimed that Mr. Vahl’s statement was “Not true.” And then he proceeded to demonstrate exactly why Mr. Vahl IS correct.”
Maybe I am reading this wrong but his statement of “Humans think/move close to linear, not to log.”seems backwards. We hear in a logarithmic way not linear.KB
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