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[GermaninLondon]

Hello
I use MC18 but I suppose my query regarding the parametric equaliser will be independent of the version. I would like to make some digital adjustments to compensate for the uneven frequency response of my speakers. I have read articles, been on the web but perhaps somebody can just give me some simple instructions what to do to achieve the following:
1. Starting at 100Hz I would like to gradually boost the bass response by 4db by 70Hz (might be 60 later but irrelevant)
2. Starting at 1KHz I would like to gradually reduce the treble response by 1 db by 14KHz.

I understand that the two are just a mirror imagine of each other so if someone can tell how to do one I can figure out the other one. I have read about Qs, setting the frequency midpoint etc and am pretty close to sorting it out myself.

I am sure that this is straightforward to anyone who has looked into this in more detail.

Thanks GermaninLondon

[Hilton]

There's lots of ways to achieve this.

This will be pretty close if my maths is correct.

Centre freq: 70Hz +4dB with Q: 1.2  which will give +4dB @ 70Hz and +1dB @ 105Hz

You wont hear the difference 1dB down at 14kHz so I'd be pretty happy with what you've got if your only talking 1dB.

If you really must you can do:

Centre freq: 14kHz -1dB with Q: 0.1 = -1dB @ 14kHz and it will be flat by 1kHz

http://www.sengpielaudio.com/calculator-cutoffFrequencies.htm

[Hilton]

You can also try high shelf and low shelf filters.
I suspect you'll prefer the previous filter though.

PS if you use this I would suggest also adding another low shelf filter at 30hz with -15dB to protect your speakers from the lower frequencies and preserve amplifier power.
No point boosting much below 40Hz if your already struggling at 70Hz. You may drive your amp to clipping or physically overdrive the speaker and damage it.

Low Shelf
Freq: 70Hz
Q: .7071
Gain: +4dB

High Shelf
Freq: 14kHz
Q: .7071
Gain: -1dB

http://www.earlevel.com/main/2010/12/20/biquad-calculator/

[GermaninLondon]

HiltonK

Thanks a lot. I was pretty close to your first suggestion!

One reason why I asked is that - as you state - you specify the centre frequency around which you put the bell-shaped equalisation with the Q determining the width (the frequencies covered). This means that the gain would decline below my centre frequency of 70Hz again, wouldn't it? I suppose it doesn't matter as I use small standmounters which don't produce much bass below that anyway.
Is the low shelf/high shelf variant a linear adjustment rather than the bell-shaped equalisation?

Thanks a lot GermaninLondon

[Hilton]

There's also free VST equalizer plugins that could do the job too. (only use 32bit VSTs)


16 band 8 channel EQ (for multi channel EQ up to 7.1 ) I use this one.
http://www.vst4free.com/free_vst.php?plugin=Marvel_GEQ&id=1530

32 band stereo EQ (TDAe EQ2032 - VST 32-Band Equalizer)
http://www.vstplanet.com/Effects/Filters_2.htm

8 band parametric EQ
http://www.vst4free.com/free_vst.php?plugin=Equilibre&id=1021

[mwillems]

Is the low shelf/high shelf variant a linear adjustment rather than the bell-shaped equalisation?

Yes; I would recommend using shelves for your application. 

[GermaninLondon]

mwillems

Thanks. Any suggestion how to implement my two simple adjustments then? I am sure it is dead easy but it would require me probably to read loads an loads of websites to figure it out myself. Any help would be appreciated!

GermaninLondon

[mwillems]

mwillems

Thanks. Any suggestion how to implement my two simple adjustments then? I am sure it is dead easy but it would require me probably to read loads an loads of websites to figure it out myself. Any help would be appreciated!

GermaninLondon

You'll want to pick the center frequency for the shelves based on the halfway point between the two endpoints. 

For the high frequency shelf, you'll want a center frequency of 7500Hz, a "gain" of -1dB and a Q of .25 or .3

For the low frequency shelf it's more complciated as JRiver doesn't support a shelf with a Q higher than 1, so you can't just dial in one shelf.  So your choices are to either dial in a parametric instead (which as HiltonK notes, may be safer for your speakers and easier on your amps) or dial in several 1 Q shelves on top of each other.  For example, I can get close to your desired response with four low shelves all centered at 85Hz, all with a Q of 1, but with gains of 1dB each.