Using the EQ

The TAE has particularly powerful EQ facilities. There are actually four EQ modules in different areas of the signal flow. All of the EQs are pretty well-specified, but the two that are part of the Rig preset system are particularly feature-rich. This post is going to go into a lot of detail about the TAE's EQs, what they can do, and how to get the most out of them.

EQ Architecture

If you look at the block diagram for the Tube Amp Expander, you'll find the four EQs. Two of them are within the Rig section, where they're called "Solo/EQs". You can save the Solo/EQ settings with each Rig. One Solo/EQ is for the signal path going to the speaker and the other is for the line outs. These are obviously meant to provide Rig-specific tone shaping, but with 20dB of additional output gain on tap, they can be used to configure a Rig with a volume boost for solos. Hence the name.

Thinking about this architecture, you may wonder why the Solo/EQs are located after the delay and reverb because the way amplifiers usually work, EQ and solo boosts are almost always before any ambient effects. But if you consider the block diagram a bit more, you realize that if the Solo/EQ was before the delay and reverb, there could only be one of them and you’d have to use the same EQ settings for both the speaker and line outputs. Although unconventional, in practice putting the Solo/EQs after the delay and reverb sounds fine and I’d much rather have the flexibility of separate EQ’s for the speaker and line out paths (which I'll talk a bit more in a moment). Boss got this decision right in my opinion.

The Solo/EQs can be configured as either 10-band graphic EQs or parametric EQs with two fully-parametric “midrange” bands, high and low shelving bands, and high- and low-cut filters. I put “midrange” in quotes because the frequency range on both bands is from 20Hz to 16kHz, which is almost the full range of human hearing, so they’re not constrained to midrange at all and that’s great. The fact that you can choose between graphic and parametric is also a really nice touch. In addition, the two Solo/EQs can be configured separately or they can be linked so that their settings remain in-sync with each other.

I like having the link option although I don't use it very much. The reason is that unless you've created a custom IR of your own speaker cab and mic, the speaker output is always going to sound a fair bit different than the line outputs with the IR speaker emulation. So having separate EQs to compensate for that is essential in my opinion. I tend to not use any additional equalization on the speaker output and dial my amp to sound the way I want it to through my speaker cab. The TAE’s attenuation capabilities are transparent enough to do that. Then I use the Solo/EQ for the line outputs to tweak the sound through the line outputs to match my speaker output sound, or even improve on it. The exception to this is when I'm creating a Rig with a specialized EQ treatment for a solo boost.

Now, if you’re going to use the Solo/EQ as a solo booster, you should be aware that because the entire TAE is post-distortion, the Solo/EQ won't boost the gain of your overdrive like a boost pedal in front of your amp would. But it will provide a sizable kick in the pants to your volume. Many people (including me) like having that front-end gain boost, but the built-in volume boost on the TAE avoids having to carry one more pedal if you can live without it. 

There are also a pair of "global EQs" just downstream of the Rig section, one each for the speaker and line outputs, However these EQs apply to all Rigs and are parametric only. They're identical to the parametric Solo/EQs except they only have one fully-parametric band and no overall output level control.

The idea behind global EQs is to provide a way to adjust the tone of all Rigs from a single set of settings. Maybe you’re plugging into a different speaker cabinet than the one you used to create your Rigs and it's a bit too bright. Or maybe you're playing at a venue or recording studio where all your Rigs sound a bit different than the way they sounded when you were creating them in your practice room. This feature would be even more useful if there were a way to adjust EQ settings from the front panel or from a mobile device. Carrying a laptop to my gigs is just not going to happen if I can help it.

So, those are the tools. Let's talk about how to use them.

Graphic vs. Parametric

First question: Which should you use, the graphic or the parametric? As in many aspects of life, the answer is that it depends.

Graphic EQs are more intuitively easy to use. They give a nice visual indication of what they're doing to your sound. However, the 10 frequency bands that can be adjusted are pre-determined. Later in this post I give some recommendations on particular frequencies to adjust to accomplish specific things. If the graphic doesn’t have one of those frequencies you’ll just have to work with the nearest one. In addition, the bandwidth of each control is similarly non-adjustable. 

Parametric EQs are more difficult to use, but they provide more precise control. You can zero in on an exact frequency and adjust a specific range of frequencies around it. It is a rifle to the graphic EQ’s shotgun. Parametric EQs are also really great at troubleshooting because sweeping the frequency control of a band and listening to the results is a quick and easy way way to find problem areas. 

In the analog world, graphic EQs used to be very noisy and had a lot of deleterious side effects on audio, but I don't think those are as egregious as they used to be. And this is guitar, not audio engineering, so as long as it sounds good it doesn't really matter.

So the choice really comes down to simplicity vs. precision in my opinion.

My personal preference is for parametric. I'm usually not a big fan of radical EQ treatments, so being able to target my adjustments very precisely is exactly what I need.

What the Hell is "Q"?

You probably know what most of the parameters are for the parametric EQs. The one that might be confusing is "Q". Q adjusts the range of frequencies, centered around whatever you have the Freq control set to, that will be boosted or cut using the Gain control. For example, if you set the Low-Mid Freq to 1,000Hz, the Low-Mid Q adjusts how much of the frequency spectrum on either side of 1,000Hz you'll be adjusting with the Low-Mid Gain control. This range of frequencies the EQ band works on is also called the bandwidth. 

What the numbers mean for the Q settings is a bit complicated. There is a mathematical definition for it that I'm not going bother with because I don't think it's very enlightening unless you think about this stuff in a math kind of way and it's also not necessary to know in order to use a parametric EQ. So I'll give you the straightforward, non-math version: The higher the Q number, the narrower the range you're affecting. The lower the Q number, the broader the range. Beyond knowing that, the best thing you can do is use your ears.

Some General EQ Tips

• It's always best to optimize the sound at the source. Get your guitar and amp to sound as good as you can possibly make it. Then use the TAE's EQs to tweak things. If you have radical EQ settings and you're not deliberately going for some kind of oddball sound, that might be an indication that you haven't dialed your amp in very well, or that you have the wrong IR, or that you simply don't like the sound of your amp very much. But hopefully not that last one!
  
• Perhaps counter-intuitively, broader bandwidth EQ adjustments tend to sound more subtle and natural than narrow ones. This is because the overall EQ curve is more gentle - the change is spread out over a broader range of frequencies.
• If all of your EQ adjustments are boosts, there is a simple one knob alternative to what you’re doing: just turn up your volume. Because that's what an all-boost EQ curve is effectively doing. 
  
• Subtractive adjustments (i.e. cuts) and broad Qs (i.e. low Q numbers) are more natural sounding. Maybe you don't want natural and that's perfectly valid. But if you find yourself thinking, "This just sounds weird," then you might want to look into your Q settings or see if you're getting heavy-handed with the boosts.
  
• Narrow notches (cuts specifically designed to reduce a problem frequencies) and broad boosts usually work best.
• You can’t boost what isn’t there. If your amp is dialed in to not produce any high frequency information, cranking up high band EQ is only going to increase noise. You have to give an EQ some sound to work with in any frequency that you're adjusting.
  
• Setting your EQ in the context of a mix is always better. You can dial in a killer sound in your bedroom, but it may not sound so great when you're playing with your band. This is another reason that not being able to adjust the TAE's EQs from the front panel or a mobile device app is a drag.
• Assuming standard tuning on a 6-string guitar, the low E string has a frequency of 82Hz. The 24th fret (assuming you have one) on the high E string is 1320Hz. This means that the fundamental frequencies on a 6-string guitar in standard tuning are between 80-1.3kHz. There are some implications to that:
• First, you’ll observe that that is pretty darn narrow range compared to the range of an EQ.
• Any adjustment you do above 1,300 Hz is affecting only harmonics. However, harmonics are one of the key elements that distinguish various instruments from each other. The fundamental frequency establishes pitch, but the harmonics establish tone and character. 
• There is very little that is good below 80Hz. In most cases, you'd do well to use the Low Cut filter on the Solo/EQs to remove or reduce it.
• Between 80Hz and 1.3kHz, any adjustments you make here can actually affect the volume of specific notes! Be careful here - broad, low-gain adjustments are best.
  

Key Frequencies for Guitar

This is where we get into an even more highly subjective area. What follows is the way I see it from 40 years of playing and recording. Your mileage may vary. I’m not recommending that you use all of these at once. Rather, if you hear a specific problem, let this be your guide to finding the right frequency to fix it. 

• 60Hz - If you’re getting a low frequency hum, it very well could be from your A/C power. Cuts here will reduce it. However, read on...
• Below 80Hz - As I wrote above, the lowest note on a 6-string guitar in standard tuning is 82Hz. There’s not much else good down there except some subharmonics from your lowest notes. If you don’t believe me, fiddle with the 31.5Hz slider on the graphic EQ - it will probably have little to no effect on your sound other than to add some ultra-low rumble. Maybe that’s your thing, but I like to clean up any of that and make room for the bass player by applying a shelving cut somewhere below 80Hz. This will usually create a lot better separation in the mix. There’s a slope to EQ shelving filters that can attenuate at and a little bit above the target frequency, so setting the shelf to about 75Hz usually works. However, if you need to tighten the low end, don’t be afraid go higher than 80Hz! It will be fine - like I said, the fundamental is actually a pretty small component of the sound. Use your ears and sweep the frequency control to find the right spot.
• 150Hz - This is where the thickness lives. If you want more or less bottom end mass this is where you work. Careful though. A little goes a long way. Too heavy, and you’ll be competing for sonic territory with the bass guitar and the overall mix will suffer for it.
• 200-400Hz - The mud zone. Back before DAWs, when we dealt with generation loss from bouncing tracks on magnetic tape, tracks would build up lots of energy around 200Hz, making things sound muddy. So I got used to doing targeted cuts of a few dBs at 200Hz. But even now, when things start to sound muddy, I’ll generally start making cuts to rhythm tracks in the 200Hz range. However, small boosts in the 250-400Hz range can beef up single-note leads nicely.
• 300-1kHz - This the midrange where the guitar makes its money. Any adjustment here should generally be small and broad.
• 700Hz - This is roughly where the midrange bump is on an Ibanez Tube Screamer. So small cuts here of no more than 3 dB and moderate Q would make it a more transparent. Alternatively, if you want to replicate that boost with the Solo/EQ, a similar sort of boost here would provide the mid hump only without any overdrive saturation increase. 
• 1kHz-2kHz - Honky Town. If your sound seems nasally or honky this where to look. Broad cuts work well in this area to create a more smooth sound, especially on rhythm guitar parts. Conversely, a little bit of boost can help bring a solo to the front of the mix. 
• 3kHz-5kHz - Cut/Presence. Harmonics, pick noise, and transients live here. A little goes a long way. If there’s high-end harshness it’s in here. Search for it by cranking the EQ gain, sweeping the frequency in this area, and listening for the offending sound to “pop”. When it does, attenuate that frequency and then set the Q just wide enough to remove the harshness and no wider. Also, cuts in this range can help with vocal conflict.
• 8kHz - Brilliance. Can be good for sparkle on clean guitars - assuming your sound has some content way up there. Often times electric guitar doesn’t, particularly when it’s overdriven. Go easy on it and again, remember, you can't boost what isn't there.