Is anyone highly familiar with equalizers? I have a few questions on how one works

jkuehlin

New member
Thought I'd reach out and see if there happens to be any lurkers here who have an in-depth knowledge of EQ's. I've reached out on several other forums and gotten zero help.

...I've been eyeballing some hardware units to try and get a super immaculate sounding hardware unit that can be used in cinematic VO. I saw a REQ2 go up for grabs on eBay, but I don't enough about them to understand what some of this means. I'm no dummy when it comes to EQ units, but this stuff may as well have been written in ancient Hebrew. Was wondering if someone can dumb this down so an idiot like me can understand it:

The REQ-2.2 equalizer utilises parallel resonant circuits in a clever configuration whereby the bandwidth (Q) of the circuit can be adjusted like an active filter, but without any complex relay switching. The inductor/capacitor resonant "tank" eq circuit runs at a low internal signal level which avoids any inductor saturation effects. The overall result is the sound of real choke based filters with a big open sound, but without the limitation of only a few - or no bandwidth selections as found on traditional choke eq's.

What is the relationship between the active filter and a relay switch?

Whats a tank circuit?

And whats a choke based filter?

we have included a saturation section that introduces measured amounts of low frequency harmonic distortion via a steel audio transformer driven by a single ended tansistor amplifier. The High Pass Filter is placed in the beginning of the eq chain and the Low Band eq section is placed last in the chain. This layout produces the best overall equalizer coherency.

What the hell is a single ended transistor amplifier? If a transistor amp isn't single ended...well...what else can it be?? I'm really fucking confused.

Ugh??? How you have HPF -> Low band EQ and also claim the unit is parallel? WTF? Doesn't that make it NOT parallel by definition?

Help. Please.
 
You've fell into the trap that happens when people interested in the 'how' something works try to make the link to 'help' people who simply want to use it practically.

Filters are pretty much everyday modules in so much audio equipment, but for something so useful, their actual physics is quite complex - I can still remember my own college electronics and being examined and having to remember resonance formulae. You had to consider Pi - frequency, inductance and capacitance. Your other question about single ended really clicks in here too - because all it really means is how the circuits are designed, think unbalanced and balanced and how we manage those. As audio is inherently balanced with positive and negative going portions of the waveform, you could design with both being processed or like unbalanced audio, a shared processing. Devices that use op amps might use differential between their inputs, or be converted in the design to simply use a level over 0. None of this matters to the user.

They are interested in what a filter can do. Filters have this attached term - 'Q'. Think of this as a quality measurement of the 'goodness' of a filter. If you use a workstation that has digital eq, it can do things that physical filters struggle with like flat-flat-flat-megagain-flat-flat. Real world filters, made with physical parts struggle with this. You can design the filter to be gentle or very sharp, but magnified, there's always an increasing slope, which many people find more musically appropriate. These circuits store a bit in a capacitor, and release it using resistors and inductors to control the flow. This is where the 'tank' term comes from.

I don't like analogies too much when taken very literally, but my old teacher compared physical filters to digital ones like this. You have a water tower to feed a small village. You open a tap and it starts to fill up at the top, you then open a tap in the downwards feed to the village to set the right water pressure. You could of course scrap the big expensive water tower, and put some big pumps in the feed coming towards the village. When everybody filled their kettles when the adverts came on the TV, the pumps would suddenly notice it and jump rapidly-is into life, boosting the pressure - but then everyone's kettle would become full and they'd all turn off the tap, and the pumps would suddenly realise and cut out. Both versions work - water comes out of taps - which one is smoothest? Which one cheapest? Then the tricky one - which one is best?

Well designed, physical filters all overlap to a degree. The overall response curve is gentler and changes gradual. Cheaper and less well designed ones can never produce a very even curve, because they don't overlap as well, or they don't overlap. Digital ones can produce curves impossible for the physical devices.

In truth - the terms 'cinematic VO' and immaculate sounding mean nothing at all. What you are describing is eq that sounds appropriate. There's a school of thought that eq should be unnecessary if the source material is already good. In truth, we often use EQ as a repair tool. Or maybe as an effect. I have a number of string sample VSTis. They all sound very different, and I choose depending on the track I am working on. If I choose the wrong one, then I find I use more EQ, like salt in cooking. If I find the right one for what is being played, EQ is minimal. I get the impression your quest is for EQ to make things nicer, so you want to treat it like an improver? I always think about guitarists. Those ones who have a characteristic sound created with a guitar, a single capacitor on a pot for tone adjustment and their amp - and of course their playing. All that needs doing is making it louder for a live show, or recording it accurately for a recording.

Forget the electronics descriptions - it's totally unnecessary and tells you zilch about what it sounds like. It's technobabble to most people but sounds wonderful in print. You say you are no slouch with EQ units. That's perfect. I understand electronics reasonably well over my career - but I really don't care how they work inside. It's only important when you need to fix one!
 
Rob's right...no end of tech data will decide whether a unit is right for you or not. Sure, for geeks like us it helps but for the user the best protocol is to demo one.
 
Hi Rob! That helps a ton...thanks for breaking that down a bit. I did take the time to look over what you wrote carefully.
 
In truth - the terms 'cinematic VO' and immaculate sounding mean nothing at all. What you are describing is eq that sounds appropriate.
In my case, the EQ that 'sounds' appropriate is the one that has a hell of a lot of design work put into minimizing artifacts and can make extremely subtle moves to a wide variety of actors. It will only be used in ADR, narration, and animation VO and will never used to color voices. This field doesn't operate with the same mindset as music EQ.... you want one unit that works on every actor because you're using it in a narrow and limited capacity, and all major studios basically use it the same way.

Forget the electronics descriptions - it's totally unnecessary and tells you zilch about what it sounds like. It's technobabble to most people but sounds wonderful in print. You say you are no slouch with EQ units. That's perfect. I understand electronics reasonably well over my career - but I really don't care how they work inside. It's only important when you need to fix one!
That's a good point. In my instance, understanding the technical babble can help me grasp the units strengths. I realize there's no substitute for simply listening to it, but at this point I'm trying to weed out expensive units that don't truly offer anything truly unique. I did the same type of research before settling on a $7000 converter, and I feel it was worth every penny. It took a little bit of work, but I feel having a good conceptual understanding of what it supposedly did better than anything else on the market (before special ordering the unit from Sweetwater) was a key factor in minimizing risk.
 
Rob's right...no end of tech data will decide whether a unit is right for you or not. Sure, for geeks like us it helps but for the user the best protocol is to demo one.

Sample craze, someone does not simply demo a $6000 equalizer, especially a highly specialized uncommon one. And tech data can help you weed out high end units that are NOT right for you.
 
I'm, to be honest, sceptical - and over design is a something that is difficult to quantify. Having a product that offers infinite possibilities doesn't mean it's better. I', intrigued by the fact that an eq offers something unique? EQ is a change to the frequency response and distribution in a waveform. Isn't that 'colour'. Your subtle adjustment to enhance one actor's voice is colour, a timbral change, or any number of descriptive phrases or words. If you over cook, it's an effect. In my humble opinion, if you introduce severe and inappropriate changes that become electronic rather than 'real' - it's bad, and this can be on a simple passive circuit or the worlds most sophisticated product. The very artefacts that worry us that get added when real filters ring, or algorithms conflict are a product that seems to come with advanced processing in analogue and digital devices. I suspect the studios use the kit the same way, and probably use very similar kit simply because the editors using them perpetuate the working method. I listen to movie sound as a consumer and sometimes wish perhaps they had used musical people rather than movie people because far too much emphasis is put on grit rather than polish. Music people round off rough edges that movie people try to create. At least, that's my perception. I cannot imagine creating the contemporary sound of dialogue in a movie - it's to my ears, so artificial and contrived, and while what the creators are doing is very clever, very precise and clean - it sounds wrong to me.

An interesting discussion. I still wonder if knowing how something works helps you use it? I would worry that knowing what goes on inside works against you, turning positive points into negative and vice versa.
 
I'm throwing in the towel on this whole thing. Had a quick chat with the director of sound engineering at Park Road Studios. He talked me out of it. And he's not the only major name engineer who has insisted that EQ's shouldn't ever be used while tracking. He's totally right. I've never thought about it like this, but he pointed out that under no circumstances is it ever possible for a tracking engineer to make an informed decision about how EQ should be applied. I was thinking that if I could make corrective moves at the tracking stage, it would save time later, but it doesn't work like this. The reason is that the tracking engineer can't possibly know what types of creative decisions the RRM's (that stands for Re-Recording Mixer) will make down the road. Digetics (for those of you who don't know those are sound sources that are directly accounted for by an event happening within he cue), scores, room tones/ambiences, music submixes, foley, and surround implementation...all this changes the EQ choices. The ADR/dialogue department rarely has access to this stuff. Its just not their job to manage EQ details. The RRM's are much better positioned to make all decisions regarding EQ. Thought you'd find that interesting.

...but I did gain some fascinating information from inquiring about those EQ boxes!!
 
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