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How to do EQ right?

alaios

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So I am very new to this. I am listening to relatively low volumes and I have tried for the first time turning in my Wiim streamer the EQ option and I picked the loudness setting. I know that this is not the "ideal" implementation as the EQ applied need to change with the volume levels buts still. The difference is huge for me. The sound becomes with less volume more spatial more rich, more wonderful.

1. If then EQ is that important why we do not like bass and treble knobs on integrated amps?
2. Do we assume that now in my Wiim I have turned EQ on the "performance-quality" of the whole system has dropped?

Regards,
Alex
 

staticV3

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1. If then EQ is that important why we do not like bass and treble knobs on integrated amps?
They're imprecise and obscure in their effect.
2. Do we assume that now in my Wiim I have turned EQ on the "performance-quality" of the whole system has dropped?
No. Frequency response is the most important aspect of any system and by far the most audible.
Even if fixing the frequency response came with a slight penalty to distortion, noise, phase, etc, I would still consider the corrected system more performant.
 
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alaios

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Okay so then:
-Bass and Treble have good motives, they are the good guys with good motivation but terrible skills :D
-I am asking relating the frequency response since many devices have this "direct sound mode" that they skipp any preprocessing stage
 

radix

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To properly EQ a system, one needs a measurement microphone. THis is a mic that is known to have pretty flat response. Popular ones are the UMIK-1, which is < $100 new. Then one uses software, like REW, to capture test tones. From these tones, one can reverse out the needed EQ to achieve a particular house curve. Other software like DIRAC or ARC Genesis or Audyssey automates that process.

The house curve is your preferred room response. Many people like a Harman curve, which has a slight bass bump and then a downward gentle slope so the highs are maybe 3-10 dB lower than the bass. For recording, the house curve is often flat, but for playback, people tend to like something different. The house curve is a bit subjective. In any case, you pick a target and then can EQ to match that target. Usually one wants to only cut frequencies, not boost a lot. There's also some limits as to what frequency range one wants to EQ and there's some problems one cannot EQ out and you need either room treatments or move the speakers a little or get another sub or use more sophisticated DSP software.
 
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alaios

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what you mean by EQ in this contenxt is to have a frequency response that follows a specific curve, e.g. house curve in your example. Is not then also the 2nd level of EQ corrections where you adjust for listening at lower volumes?
 

staticV3

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what you mean by EQ in this contenxt is to have a frequency response that follows a specific curve, e.g. house curve in your example. Is not then also the 2nd level of EQ corrections where you adjust for listening at lower volumes?
A good system starts with a neutral frequency response.
A measurement microphone can be used to diagnose the response and apply fixes if necessary.

Equal loudness correction à la ISO 226 can be applied on top of this if desired, and can in certain circumstances improve sound quality a lot,
 

dominikz

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IMHO tone controls have their place - they can be used for tweaking the overall tonality of the system to taste.

The way I see it, we can have several EQ stages at the same time:
1) Precise EQ for room resonance correction at low frequencies (based on in-room measurements)
2) Loudspeaker correction EQ at higher frequencies, if needed (based on complete spinorama-style anechoic measurements)
3) Dynamic loudness EQ to compensate for perceptual lack of bass at low-level listening volumes (compared to reference levels)
4) Tone controls to modify system tonality to personal taste, mood or individual tracks
 
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IMHO tone controls have their place - they can be used for tweaking the overall tonality of the system to taste.

The way I see it, we can have several EQ stages at the same time:
1) Precise EQ for room resonance correction at low frequencies (based on in-room measurements)
2) Loudspeaker correction EQ at higher frequencies, if needed (based on complete spinorama-style anechoic measurements)
3) Dynamic loudness EQ to compensate for perceptual lack of bass at low-level listening volumes (compared to reference levels)
4) Tone controls to modify system tonality to personal taste, mood or individual tracks
What happens if you have Dirac Live correction applied upstream and then downstream on your amplifier use for example Yamahas loudness knob or bass/treble tone controls?

What does that do to the corrections / phase etc. that Dirac has done upstream?
 

dominikz

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What happens if you have Dirac Live correction applied upstream and then downstream on your amplifier use for example Yamahas loudness knob or bass/treble tone controls?

What does that do to the corrections / phase etc. that Dirac has done upstream?
If the tone control is implemented post room EQ (as it should be), compensates with pre-gain for sufficient headroom (as it should) and operates on all channels equally (as it should) I see no issue.
EQ is a linear process that can be cascaded without issue if implemented correctly.
 
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If the tone control is implemented post room EQ (as it should be), compensates with pre-gain for sufficient headroom (as it should) and operates on all channels equally (as it should) I see no issue.
EQ is a linear process that can be cascaded without issue if implemented correctly.

I'm thinking more in the way of frequency dependent delay / phase-shifts and if this messes up what Dirac does to the signal up-stream?
 

dominikz

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I'm thinking more in the way of frequency dependent delay / phase-shifts and if this messes up what Dirac does to the signal up-stream?
It shouldn't, no. As I mentioned, EQ is a linear, time-invariant process and can be cascaded. Note that Dirac Live is also in essence EQ (with a possible exception of ART - I haven't really looked into how that works yet).
 
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It shouldn't, no. As I mentioned, EQ is a linear, time-invariant process and can be cascaded. Note that Dirac Live is also in essence EQ (with a possible exception of ART - I haven't really looked into how that works yet).
That's not entirely true, is it? When linear phase EQ exists I mean. As such I don't know how the downstream EQ circuits on a bass / treble or loudness in a Yamaha amplifier works.
If a signal is passed through networks of inductor or capacitor to manipulate it, what happens to the "finished" signal after both Dirac and analogue EQ?

Dirac writes this on their website:
"Dirac Live delivers phase alignment, speaker driver alignment, room resonance reduction, and e"
 

dominikz

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That's not entirely true, is it? When linear phase EQ exists I mean.
It is actually true, at least to the best of my knowledge, but I see how terminology like "linear process" and "linear phase" can cause confusion. I'll do my best to try and explain the difference in plain language without going too deep into the formalities of signal processing theory.

A linear, time-invariant (LTI) system or process is one that acts the same regardless of signal level or the point in time where you apply it. It doesn't remember what happened before and doesn't create new frequency components. It just applies a constant change to the input signal.
A simple example of such a process is a volume control (just changes signal level between input and output) or EQ (manipulates the signal frequency magnitude or phase responses, or both, in a constant way).

Linear phase EQ and minimum phase EQ are therefore both linear processes, the only difference between them being how they affect the phase of the signal. Minimum phase EQ will modify both the frequency magnitude response and the frequency phase responses together, and a linear phase EQ will modify just the frequency magnitude response and will not touch the frequency phase response.
Here's an example of minimum vs linear phase EQ in IK Multimedia ARC:
index.php

index.php


On the other hand, a non-linear process is something that doesn't satisfy the above conditions.
Typical examples of non-linear processes are distortion (it adds new frequency components - harmonics, which also change in level with input signal level) and dynamic processing such as compression (where output changes based on input level).

As such I don't know how the downstream EQ circuits on a bass / treble or loudness in a Yamaha amplifier works.
If a signal is passed through networks of inductor or capacitor to manipulate it, what happens to the "finished" signal after both Dirac and analogue EQ?
Adding EQ on top of EQ is basically just multiplication of the two EQ responses in the frequency domain (which is equivalent to convolution of impulse responses of both EQs, as Fourier transform theory teaches us).

I.e., you could basically build one single EQ filter that is equivalent to what Dirac Live processing + Tone control processing does, if you know their individual responses.

Dirac writes this on their website:
"Dirac Live delivers phase alignment, speaker driver alignment, room resonance reduction, and e"
From my tests, Dirac Live "Phase alignment" comes mainly from use of minimum-phase filters (which also solve room resonances) and constant delays (to time align loudspeakers at different distances); and speaker driver alignment comes from use of all-pass filters (a type of non-causal EQ normally implemented as FIR) to counteract crossover filter phase wrap. These are all types of EQ filters.

The part that I suspect is not just EQ is Dirac Live ART - but as I said, I haven't really looked into how that works in any depth.

Hope this was interesting and (even better) useful! :)
 
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alaios

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IMHO tone controls have their place - they can be used for tweaking the overall tonality of the system to taste.

The way I see it, we can have several EQ stages at the same time:
1) Precise EQ for room resonance correction at low frequencies (based on in-room measurements)
2) Loudspeaker correction EQ at higher frequencies, if needed (based on complete spinorama-style anechoic measurements)
3) Dynamic loudness EQ to compensate for perceptual lack of bass at low-level listening volumes (compared to reference levels)
4) Tone controls to modify system tonality to personal taste, mood or individual tracks
Interesting reply, so according to this view the 4) tone controls is kind of giving a specific "twist" of the music based on how you feel on that day. I liked that. Although I understand that are people that they like the to get the original signal as pure as possible.
 

dominikz

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Interesting reply, so according to this view the 4) tone controls is kind of giving a specific "twist" of the music based on how you feel on that day. I liked that. Although I understand that are people that they like the to get the original signal as pure as possible.
Indeed, people are absolutely entitled to their preferences. Also, recorded music varies hugely in tonal balance, so some like to try and correct for that.
Dr. Toole also often advocates for the use of tone controls - e.g. see this quote (link to source):
Spectral balance variations in recordings are abundant. I have for decades argued for the liberal use of tone controls - but sadly some under-informed "high end" folks think they are the work of the devil, and they cannot be found in all electronics. They also need to be easily accessible, not buried in layers of software menus.

The "tilt" control in the old Quad preamp was another step in the right direction. It was a crude tilt, being the result of linking the tone controls - bass boost/treble cut, or bass cut/ treble boost. Much later, Lexicon provided at tilt control in it's processors and because it was digitally created it was truly a linear bass-to-treble tilt. Very useful indeed. One needs such controls if paying attention to spectral balance while listening.

It is IMHO still good practice to start from a 'neutral' response - so I'd always suggest to start with neutral/well-measuring loudspeakers, integrated with good subwoofers, all placed for optimal in-room response, and all calibrated with EQ below the room transition frequency.
Then use tone/tilt controls to manipulate overall tonality to taste (and always having the option to revert to the neutral reference) :)
 

DVDdoug

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If then EQ is that important why we do not like bass and treble knobs on integrated amps?
Who is "we"? :p

If you are correcting the room/speakers, an equalizer obviously allows much more precise correction.

I think "audiophiles" try to avoid anything that alters the sound. In the old days I used to read the magazines and I thought it was an admission that my system was inferior if I had to adjust the tone controls... That was a long time ago in the analog days, when many (most) vinyl records really needed some tweaking.

Bass & treble controls are super-handy for making quick adjustments to particular recordings, whether overall equalization has been applied or not.

It's also a quick way to handle loudness compensation (boosting the bass, or bass & highs, at lower levels), since "loudness" switches have become less common.
 
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Who is "we"? :p

If you are correcting the room/speakers, an equalizer obviously allows much more precise correction.

I think "audiophiles" try to avoid anything that alters the sound. In the old days I used to read the magazines and I thought it was an admission that my system was inferior if I had to adjust the tone controls... That was a long time ago in the analog days, when many (most) vinyl records really needed some tweaking.

Bass & treble controls are super-handy for making quick adjustments to particular recordings, whether overall equalization has been applied or not.

It's also a quick way to handle loudness compensation (boosting the bass, or bass & highs, at lower levels), since "loudness" switches have become less common.
I also think that the type of audiophile you mention here is put off by tone controls because they want to chase that perfect sounding amplifier, preamp, DAC and tune it with expensive cables.
 

droid2000

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I also think that the type of audiophile you mention here is put off by tone controls because they want to chase that perfect sounding amplifier, preamp, DAC and tune it with expensive cables.
They are living in the Dark Ages of audio reproduction. Praying to the supernatural gods of power supplies, upgraded 110/220 outlets, and oxygen-free cables. The right incantation, the right potion, will reveal pure sound. Surely the hi-fi witch doctor who is incentivized to sell you the most expensive gear knows best. Their bass response sounds like a $125 boom box, but that'll be fixed with the new REL subs using high-level connections to the mains.
 

Yorkshire Mouth

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Maybe it's just my age, or when I got into hi-fi, but I remember arguments against EQ being a little different back in the late '80s.

The idea then was that hi-fi should be as 'clean' and undistorting as possible, that your kit should just get out of the way of the music.

Tone controls were frowned upon, as that was two extra pots the signal had to go through. So a 10-band graphic equaliser was sacrilege; you were just asking for trouble. Get a proper, clean signal and it'll sound good, don't try to fix problems with EQs which only make matters worse.

The reason modern EQ has become popular is that it's done in the digital domain, where you're not adding distortion, well certainly not the amount made by passing through a row of sliders.

But some audiophiles still have a built in prejudice, despite it being outdated.

But the whole audiophile thing has now become so hypocritical. As I say, it used to be about getting the cleanest signal path, which cost a lot of money. Now, objectivists are all about low noise and distortion, and audiophiles buy tube amps. And ask how you can possibly think a £100 DAC can sound even remotely as good as a £1,000 DAC, no matter how well it measures BLAH BLAH BLAH…
 
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