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B.Flat

Parametric eq

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I am interested in opinions and technical facts regarding parametric equalisation, particularly with regard to where the eq is applied, i.e. on-board  or at the amp preamp stage.

Should a certain frequency cut, or boosted, by the same level of db, on-board or at the amp produce the same audible result, all other eq being equal.

Any views on pros and cons re. on-board versus at the amp would also be of interest.

 

 

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I have parametric EQ on my amp and have had it on an instrument and in all honesty,  I  don't think it's ever helped me achieve the sound I  liked on the night. Not much help I  know but if your interest is going to result in you spending money, I'd really think twice about it. Most modern active basses have 3 band EQ on board and I've found that sufficient.

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Hi leschirons, interesting view. I also have a parametric on my elderly Yamaha PB1, which I do find very useful to tune my rig to the room I am playing in.

I also have a Vigier Passion ii with semi-parametric mids, again useful. The reason for my post is that I have a Noll three band full parametric preamp which I would like to install in something like a p/j configuration bass, but am wondering if it will offer any advantage over my existing rig

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My Passions have semi-parametric preamps which work very well. Parametric is a powerful tool if you get accustomed to it. I have a parametric pedal (simple Artec, works well, too), and a tce 1144, which is a classic. In a boomy place parametric is far better than basic two or three band eq, but the usage is slightly more complicated to understand than a 2/3-band unit.

I downright love parametric, but took a bit of time to get the most out of it.

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Let's make a slightly clarification concerning parametric EQ.

A full parametric EQ includes, gain, frequency sweep AND Q factor adjustment.

A semi parametric EQ does not have the Q factor.

So what's the Q factor ? It's basically the width of the chosen frequency.

Most people can't use full parametric EQ correctly because they don't understand how it works. Hence getting outer space sounds.

If you know how to use it, it's a fantastic tool; if you don't, it's a sound destroyer.

A semi parametric with a fixed Q factor adjustment badly chosen will be a real pain in the *ss to use.

The Noll preamp you're talking about @B.Flat is a semi parametric EQ and the Q factor is not indicated, as (quite always) usual...

Screenshot_2020-03-21-11-25-22-622_com.android.chrome.thumb.jpg.411cd150a5a6dfbdfdc1214ee135e01b.jpg

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Two bands of full parametric eq would allow you to realise virtually any sound your bass was capable of but remember that that would entail six controls (Boost/cut, centre frequency and Q width for each band) and could be even more complex if you included Q shape.

I'm a fan but I don't think I'd want it actually on my bass - definitely outboard but mainly for recording.

For live, to my mind a better compromise would be a good filter preamp or even just a semi parametric mid range control - much easier to manage in a hurry.

That said, I love the Stingray 2 eq style circuit for a bass that has a pickup at or near the bridge position and most gigs I just play with my bass tone control(s) fully open. I have enough other stuff to worry about.

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14 hours ago, B.Flat said:

Hi leschirons, interesting view. I also have a parametric on my elderly Yamaha PB1, which I do find very useful to tune my rig to the room I am playing in.

I also have a Vigier Passion ii with semi-parametric mids, again useful. The reason for my post is that I have a Noll three band full parametric preamp which I would like to install in something like a p/j configuration bass, but am wondering if it will offer any advantage over my existing rig

I guess it all depends on how keen you are to achieve a particular result and if you regularly have problems at certain venues achieving that particular result. I must admit, I am a bit of a "that'll do for tonight" kind of a guy. As long as it sounds okay to me (I check out front at sound checks to make sure I'm not too loud, quiet, toppy or boomy) and no-one complains about anything, I'm set.  I had a Vigier Passion with the semi para mids years ago and did actually use the function on that but recent years have seen a change to more traditional and simple controls on instruments for me.

Anyway, good luck on your quest.

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Your comments are correct Hellzero, especially about the "Q" control. Fortunately the Yamaha PB1 has all three, sweep, gain & Q, and is perfect for room ambience corrections. The slope on the Noll is not at the extremes either way

However my main question is what, if any, does anyone think the audible difference is  between applying PEQ at the initial signal (instrument) or at the preamp stage of the amp.

Of course the other tone settings at either end of the chain will have a big influence,  but I am assuming "flat" in both cases.

 

Ultimately the only thing to do is to try it, but I thought a bit of exploratory enquiry might throw up things I have not thought about, or indeed others experience.

1 hour ago, Hellzero said:

Let's make a slightly clarification concerning parametric EQ.

A full parametric EQ includes, gain, frequency sweep AND Q factor adjustment.

A semi parametric EQ does not have the Q factor.

So what's the Q factor ? It's basically the width of the chosen frequency.

Most people can't use full parametric EQ correctly because they don't understand how it works. Hence getting outer space sounds.

If you know how to use it, it's a fantastic tool; if you don't, it's a sound destroyer.

A semi parametric with a fixed Q factor adjustment badly chosen will be a real pain in the *ss to use.

The Noll preamp you're talking about @B.Flat is a semi parametric EQ and the Q factor is not indicated, as (quite always) usual...

Screenshot_2020-03-21-11-25-22-622_com.android.chrome.thumb.jpg.411cd150a5a6dfbdfdc1214ee135e01b.jpg

 

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If you hear the eq that is set flat, it is of low quality. tce 1140 (sorry, that's mine, not the 1144) is dead quiet when flat, but if turned to extremes, anything can be noisy. Do not forget that the signal source is also one part of the equation. If the preamp (and any preamp, that is) is inside the bass, the power consumption has to be so small, that it may already affect the sound quality. (Alembics are an exception with their external PSUs. Their usage of that power hungry NE5534 is certainly one part of their sound.)

An outboard unit with 230 V power line and lots of amperes is not limited the same way as the tiny unit with single 9 V battery problems. A tube preamp like an Alembic F-1X inside the bass? Overkill. And definitely does not work with that single battery. Of course you can leave all adjustments of the bass out and put that outboard unit straight after your bass. I bet you get better quality than with a small Sadowsky (and a tiny battery), but also different.

We need to think about the practical side, too. If your work is in studio, the built-in bass preamp (or those terrible carbon pots) is the worst quality element in the signal path. But it is very feasible for the gigging bassist that has to change the sound on the run - and some noise in the circuitry does not mean a thing in live situation.

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I've had a few different parametric eq devices in my bass rig and have found never found them useful. Theoretically, they offer the best way of tailoring your sound to fix problems with your equipment or with the room, but in practice I've found that they offer too many options. As long as the frequencies are correctly specified, a broader based five-band tone control works for me. Even then, I find I only ever need to use the low bass and lower-mid bass controls in live situations.

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Posted (edited)
5 hours ago, B.Flat said:

However my main question is what, if any, does anyone think the audible difference is  between applying PEQ at the initial signal (instrument) or at the preamp stage of the amp.

 

 

Mostly the same as applying any form of EQ - it depends. One immediate problem is that true PEQ requires at least three or four gain stages, and that means a fair bit of current consumption. So right off, putting it off the bass is mostly a better choice IMO and IME.

Gain staging is critically important and  in my own designs I prefer to have gain controls both pre and post any EQ blocks that might actually get set with a lot of gain or cut. In most of my DIY amps I have a single band full parametric stage after bass and mids, but before the treble section. That minimizes how many stages boosted treble signal goes through, which helps signal to noise ratio a lot. For bass guitar I tend to use it more like a tilt control than a surgical boost/cut with a narrow bandwidth. For something like upright bass just the opposite though, and putting the PEQ after bass and mids lets me massge unwanted interactions between those controls.

PEQ can be a tweaky thing and for most people using it on the fly is apparently  just overwhelming. Hence the dumbed down semi- PEQ we see in many  implementations. As a long time sound provider I am very used to quick on the fly tweaks, especially for feedback suppression. As a bass player I tend to set it once for room correction and call it done. Horses for courses.

Edited by Passinwind
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I think an old Hartke head I had - HA4000 - had either para or semi-Para on it. Whichever it made it extremely easy to get the sound I wanted, tho have to admit it was more by trial & error than any real knowledge.

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Thanks for all responses, especially itu and passinwind.

On balance I think I will abandon the onboard three band semi-parametric route and just continue to use the  Yamaha PB1 true parametric as a room-tuner.

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dBs are relative. A 3dB cut is a halving of the signal. Regardless of that signal strength. So yes. It should have the same effect whether you apply that at the bass, at the preamp or at the output of the amplifier. 
 

Is that what you’re asking? 

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One thing that might help is to read some notes from the people behind the mixing board. You could get lots of hints from Sound-on-Sound pages, where seasoned people tell about bass and how to eq it. Their search has been powerful with terms like "mixing", "bass", and alike. It is easier to try some known frequencies and how they affect your personal sound. Then it is recommended to do a personal investigation through the frequency spectrum.

Remember: you can add and boost some freq, or damp the others. Boost sounds good because the volume was raised, but is the sound something you really were after, if the loudnesses are even?

www.soundonsound.com

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On 21/03/2020 at 23:30, Passinwind said:

For bass guitar I tend to use it more like a tilt control than a surgical boost/cut with a narrow bandwidth.

Funnily enough, this is exactly what I've been looking for in a para eq...a notch filter with a super narrow bandwidth for boosting around 250Hz.  Are you suggesting the narrow bandwidth isn't a good idea?

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1 hour ago, Kiwi said:

Funnily enough, this is exactly what I've been looking for in a para eq...a notch filter with a super narrow bandwidth for boosting around 250Hz.  Are you suggesting the narrow bandwidth isn't a good idea?

Pedants 'R Us: a notch filter won't boost at the center frequency, so it's probably not the right tool here. If you can describe the problerm you're trying to fix maybe we can  collectively work through it?

With a full PEQ it's a tricky deal, because using much boost with a narrow bandwidth tends to promote ringing (oscillation), something you may see on an oscillosope well before you can hear it, and unfortunately a potential speaker killer. The area around 250Hz is a very important range, it can equate to "mud", room resonance, what some people think of as "punch", and so on. FWIW, the PEQ design in my amps can get as narrow as 1/20th of an octave. I can't recall ever using that setting with bass guitar though. 1/3rd or even 1/6th octave, maybe.

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8 hours ago, Passinwind said:

Pedants 'R Us: a notch filter won't boost at the center frequency, so it's probably not the right tool here. If you can describe the problerm you're trying to fix maybe we can  collectively work through it?

With a full PEQ it's a tricky deal, because using much boost with a narrow bandwidth tends to promote ringing (oscillation), something you may see on an oscillosope well before you can hear it, and unfortunately a potential speaker killer. The area around 250Hz is a very important range, it can equate to "mud", room resonance, what some people think of as "punch", and so on. FWIW, the PEQ design in my amps can get as narrow as 1/20th of an octave. I can't recall ever using that setting with bass guitar though. 1/3rd or even 1/6th octave, maybe.

thanks, I'll pm you as it could get a little long winded. 

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Just how long are you going to spend twiddling at soundcheck and then STILL fiddle during the gig? There are too many amps with too many knobs and sliders out there. A simple bass/lower mid/mid/high mid and treble should be enough for any gigging muso. Set it up and play a couple of numbers and adjust the mid if needed during the evening as the place fills up with frequency soaking people. I had a Hartke combo with more sound altering knobs, buttons and sliders than were actually useful and never found a sound I liked while I owned it. Leave the twiddling to the mixer guy or studio engineer I say. 

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2 hours ago, LITTLEWING said:

Just how long are you going to spend twiddling at soundcheck and then STILL fiddle during the gig? There are too many amps with too many knobs and sliders out there. A simple bass/lower mid/mid/high mid and treble should be enough for any gigging muso. Set it up and play a couple of numbers and adjust the mid if needed during the evening as the place fills up with frequency soaking people. I had a Hartke combo with more sound altering knobs, buttons and sliders than were actually useful and never found a sound I liked while I owned it. Leave the twiddling to the mixer guy or studio engineer I say. 

And as a gigging musician I’d agree 100% 👍

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5 hours ago, LITTLEWING said:

Just how long are you going to spend twiddling at soundcheck and then STILL fiddle during the gig? There are too many amps with too many knobs and sliders out there. A simple bass/lower mid/mid/high mid and treble should be enough for any gigging muso. Set it up and play a couple of numbers and adjust the mid if needed during the evening as the place fills up with frequency soaking people. I had a Hartke combo with more sound altering knobs, buttons and sliders than were actually useful and never found a sound I liked while I owned it. Leave the twiddling to the mixer guy or studio engineer I say. 

I’m afraid that I have to disagree. Once you learn how to set up a semi parametric EQ, it is relatively easy to sweep for / adjust one troublesome frequency on a gig compared to having to deal with just four fixed controls.

I virtually never touch the EQ section on my Mesa mpulse, except to adjust the frequency centre of the low mids if there is an issue with the room. If I am using an amp without a semi parametric then its much more difficult to isolate a troublesome frequency or to boost if you need to cut through.

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Room acoustics change pretty rapidly. A sound check in an empty room will change when the room fills and then change again depending whether the audience are all standing at the bar, moving to seats, or jumping around in front of the band. 
 

I’d say PEQ is only any use on the mains PA and /or the monitors to deal with feedback and cutting problem frequencies. 
 

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I do not use my amp's eq (it can be switched on/off), if the bass has eq and other adjustments. But as I have basses with no adjustments, then the amp comes to play.

PEQ is powerful in gigs, where some frequencies try to ruin playing. I have been in few places, where playing without parametric would have been nearly impossible. Key thing was to understand its functionality and then learn how and where to use it. I need, I can, and I use it. If a tool is not for you, fine, I will survive.

tc electronic produced a parametric pedal with two bands. Price is steep, a used one can be found at around £300. There are few modern versions in pedal format, Artec being the cheapest.

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Empress do a para eq pedal as well.  But you can buy onboard para eq - I have two or three loaded into basses by Klaus Noll.  Really good quality, if you go for one just ask him to adjust the mid frequency down to 250Hz or so.  It's a little high in the standard circuits.

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Nöll is a semi-parametric. I do not recall any on-board preamp with full parametric eq, but there are quite a few without Q (BW). Status Paramatrix has two semiparametric eqs!

Here are few full PEQs in pedal format, semiparametric units are left out:

AER pocket tools dual para eq

Alix Grace

Aria PE-10

Arion SPE-1

Artec SE-PEQ

Broughton Audio

BYOC PEQ

Carlsbro PEQ (call this vintage)

Chasebliss Condor

Correct sound PEQ

Empress Para EQ

Fishman dual parametric DI

Guyatone PS-008

Ibanez PPE1

Ibanez PQL

JPG the tweaker

KHDK Paranormal

KORG PEQ

Onkart Gromt Turbotore

Orange BaxBangeetar

Pearl PE-10

Pettyjohn Filter

Revival electric metric

Sine effects microPara, MiniPara, and MegaPara

Stone deaf effects PDF-1(X), and -2

tc electronic Dual PE, Sustain+ PE, and Classic Sustain+ PE

WMD utility PEQ

Yerasov SCS PQ-10B

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