Graphic equalisers

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#1 Graphic equalisers

Post by Ant »

Simple question, probably with a massively complicated answer, probably one that our chris is best placed to answer.
Is there any none cobblers hifi mag reason not use a graphic equaliser to tweak system response using rew/interface/mic.

Reason being, i am curious to see what balance i can get out of the speakers, mainly at the very bottom end and around fr. Not necessarily more bass, im looking at response hole plugging and smoother rollof. I dont want to do it in software because i cant feed the tts through it and wouldnt want to anyway because of my luddite tendencies

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Max N
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#2 Re: Graphic equalisers

Post by Max N »

I remember the days when graphic equalisers (along with FFT type displays) were common, often built into the system.
Some of them had a bypass or direct switch, and I can’t remember hearing a big difference.
I suppose there are filters - are they passive? Would they introduce phase lag?
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#3 Re: Graphic equalisers

Post by rowuk »

Linkwitz Transformation is a possibility here. Here is Rod Elliots/Jeremy Wolfs take and circuit:

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Mike H
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#4 Re: Graphic equalisers

Post by Mike H »

Had a cheap one from Maplin once, but then my system got better, and I realized it sounded really naff. Could have just been because of the nasty slider pots I suppose. Pretty sure it used op-amp gyrator circuits to emulate inductors. As there were 10 bands for each L and R channels, lots of components in the signal paths... doubtless SMD... I seem to remember there was a 'daughter board', or maybe two of them, one for each channel, containing the 'dark art bits', and dipped in grey resin (to keep it secret?).
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#5 Re: Graphic equalisers

Post by brig001 »

I think the only problem with using a graphic EQ for that is that it is unlikely to have the frequency that you need. I have a hole on the left speaker at 70Hz due to a bay window and plug it with a boost on the right speaker. It needs a Q of 5, so quite narrow

I think using DSP is the way forward, even if it is just to find out exactly what you need, but it sounds like you don’t want to go down that road as a permanent solution

Do you know what exactly is required?
Rod Elliot has some circuits for parametric EQ which might be more suitable

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