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Topic: Presence setting |
Fred Glave
From:
McHenry, Illinois, USA
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Posted 13 Mar 2012 7:51 am |
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What exactly does the presence setting do? I've made adjustments to it on my Roland Cube 80, and I don't hear what it is doing. Maybe it's my old ears.
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Zum Encore, Zum Stage One, Fender 2000, Harlan Bros., Multi-Kord, |
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Tim Marcus
From:
San Francisco, CA
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Posted 13 Mar 2012 9:03 am
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here is how it works on a tube amp, where the presence knob is essentially a tone control on the negative feedback loop:
When you add presence, you are essentially subtracting high frequencies from the negative feedback loop. Since its negative feedback, it works in opposite - so the control adds more high frequencies by subtracting the added negative frequencies from the signal.
its a bit complicated - but think about it in terms of the presence adding brightness to the output stage of the amp, after the tone stack. But its not adding brightness - its subtracting low end and midrange.
Now for my opinion - presence has no business in a steel amp. Every time I have to use an amp with presence control I turn it down to 0. I feel like I get enough high end from the treble control, but then again I personally like things to be on the dark side. Something I noticed after marketing pedal steel amps is that the young players like it dark, and the older guys like to crank up the high end... think its got to do with hearing loss like you said! I am sure I will use that presence control some day
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Milkmansound.com |
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Fred Glave
From:
McHenry, Illinois, USA
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Posted 13 Mar 2012 9:46 am
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Thanks Tim. That explains a lot. I do have some disatisfaction with too much high end. I'd like it a little darker. I think that the high end may be causing some distortion. Could that be?
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Zum Encore, Zum Stage One, Fender 2000, Harlan Bros., Multi-Kord, |
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Tim Marcus
From:
San Francisco, CA
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Posted 13 Mar 2012 10:20 am
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I doubt its causing distortion - but it may be revealing or accentuating the distortion that's caused by something else up the line. Presence is subtractive, and generally at the end of the line.
I am not sure how the Roland Cube amp works, but my suspicion is that as a concept it is not residing anywhere near the pinnacle of audio engineering and construction...
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Milkmansound.com |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 13 Mar 2012 12:55 pm
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Unlike the concepts of "treble," "bass" and "midrange, the idea of what "presence" consists of is not defined by any engineering convention and is therefore left to the fancy of the amp designer to implement. When included as part of a preamp's tone stack, "presence" controls may affect any of various mid- or high-frequency bands, I have seen EQ centers from 1kHz to 12kHz identified as such on instrument amplifiers and mixing consoles.
However, to expound upon details given here by Tim Marcus, in most Fender tube amp designs the Presence control is not part of the tone stack at all but a grounding filter applied to a separate signal derived from the secondary of the output transformer (i.e. the speaker jack) and fed back to the inverse input of the power tubes. In these amps, the general effect is to increase the seeming volatility of the amp's attack response, and the frequencies affected will vary between various amp models. For pedal steel guitar the resulting increased high frequency energy is generally detrimental to a clear, balanced tone. |
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