Category Archives: Effects FAQ

Effects questions answered

How to use a Delay, Part 1

The delay is a favorite effect of mine. I remember the first time I tried one, I thought I was David Gilmour for a minute.  It is probably one of the most useful effects out there. It offers a world of possibilities but it usually requires some practice to master. I will explore the main uses of a delay in a series of posts. Part 1 is dedicated to the creation of rhythmic patterns using a delay and we will see how to recreate the basic “U2” delay effect. Later, in Part 2, we will focus on the ability of this fabulous effect to fatten your tone and discuss the differences between analog and digital delays.

The Electro Harmonix Deluxe Memory Man Analog Delay and the BOSS DD-3 Digital Delay, two very popular models
The Basics

What a delay does is repeat the notes you are playing on your guitar once or several times, each repetition being usually softer than the previous one. You encounter a similar effect in nature when shouting in a valley or a cave. The time between the repetitions can be chosen through a “delay time” setting on most units. It is usually labelled in milliseconds and ranges from a few milliseconds to several seconds for the most sophisticated models. The number of repetitions is usually defined by a “feedback” setting. Most units also offer a “level” or “mix” control which determines the amount of dry signal versus the delayed signal. Often, delays are also called echos. There is a difference though: delays can have an infinite number of repetitions whereas echos have a limited number.

To clarify, a delay unit should at least offer three settings: delay time, feedback and mix/level. More recently, delays have been incorporating many other settings which I mention further down.

Delay Time and Tempo

You will often read or hear that the delay time should be set according to the tempo of the song you are playing. I don’t think this is always true. If you are using the delay to obtain a rhythmical effect (think The Edge from U2 or Pink Floyd’s “Run like Hell”), then yes the delay time should follow the tempo of the song. But if you are using the delay to fatten your tone (as we will see in Part 2), I don’t think following the tempo of the song is so important.

Using the delay for rhythmical effects: the infamous dotted eighth

The Edge, U2’s guitarist, has made the use of rhythmical delay effects his trademark. In the beginning of  his career in the early 80s, he was already using a delay to make out as if he was playing more notes than he was actually playing. The trick was that the notes “played” by the delay were in sync with the tempo of the song which gave U2’s songs an amazing “pulsation”.

At the time, he was only using analog delays which means the settings had to be done “by ear” and that is not that easy. It also meant that the drummer had to play in sync with the delay. This led The Edge and U2 to drop the delay on their second album (“War”). It was of course back in full force on the subsequent albums on songs like Pride or Where The Streets Have No Name, probably helped by the arrival of digital technologies.

It is easier nowadays to get the same kind of effect using a digital delay unit or a software plugin which allows you to set the delay time to the millisecond. The basic “U2 delay effect” is obtained by setting the delay time to a “dotted eighth”. The feedback should be set so that you have about three or four repetitions and the level/mix quite high, at about 50%. Then, all you have to actually play are eighth notes, the delay will do the rest (see the audio examples below). Note that a dotted eighth is equivalent to 3/16th of a note.

Here is the formula to calculate the delay time so that it falls on a dotted eighth:

delay time in ms = (240000/tempo)x3/16.

Let’s take an example. At a tempo of 120 BPM, divide 240000/120, you get 2000. Multiply 2000 by three and divide by 16 and you get 375ms.

Here is an audio example at a tempo of 120BPM, WITHOUT any delay first:

Audio MP3

Then the exact same thing augmented by a delay set at 375ms, 3 or 4 repetitions and mix at 50% (I have used the delay integrated into my Boss MICRO-BR recorder with the feedback at 13):

Audio MP3

Pretty cool!

Some pedals spare you the cumbersome calculations and allow you to actually do this while playing alongside a drummer in real time, and without any prior knowledge of the tempo. They do so thanks to two extra features that most delay pedals don’t have: a “tap tempo” function and a setting that allows you to choose the delay time based on a “musical” subdivision (dotted 8th for instance). The Tap Tempo allows you to “tap” a pedal in time to set the value of the delay time “on the fly”.  So on these particular models, you can select “dotted 8th” and tap alongside your drummer and voilà, the delay should automagically be in time.

These models include the BOSS DD-20 Digital delay, the Line 6 Echo Park,the TC Electronic Nova Repeater or the super duper boutique high end Providence CHRONO DLY-4. A lot of pedals have got a Tap Tempo feature nowadays but not that many have the ability to select a “musical” subdivision. A note to BOSS DD-7 users: there are a few musical subdivisions (including dotted eighth) that can be selected using the mode selector, check out the manual.

Finally, know that the dotted 8th is not the only interesting subdivision, it is just one that has been used time and again on numerous hits. As always, feel free to experiment! There are two really cool websites you might want to check out if you are into using delays for rhythmical effects: this one by Tim Darling which deals with everything “The Edge” and this one by David Battino which is more generic.

In Part 2 of this series of posts, we will see how we can sound like a guitar hero by fattening our tone using a delay. Stay tuned!

Using two overdrive pedals simultaneously

Combining two overdrive pedals is a topic that pops up often in guitar forums. I suppose the fact that Stevie Ray Vaughan used that kind of configuration at some stage in his career has a lot to do with it. I did quite some experimentation over the years in that “field”, and I thought I should share with you what I have learned.

Boss SD-1 and Analogman modded TS9

I will write here about combining two overdrive pedals and I will leave distortion and fuzz pedals for future posts. As I show in a video below, you can get interesting tones out of two overdrive pedals. Why not use just one pedal but with more gain, you might ask? Well, the answer is that two overdrive pedals don’t sound like one pedal with more gain. In addition, it gives you more tonal options since you can switch one of the two pedals on, or the two together. That makes four different tones in total if you count the clean tone.

But you have to know that some combinations work and some don’t. It is hard to predict how two overdrive pedals will interact. By not working, I mean that it might sound overly squashed or very fizzy. Getting the right settings is also very important. I find that when you use two overdrive pedals together, it is rarely a good idea to have one (or the two) with the gain maxed out. Try with lower values first.

I have recorded a video showing how my Analogman modded Ibanez TS9 plays with a stock Boss SD-1. Both pedals have the drive and level at 12 o’clock. The tone is at 9 o’clock since my Fender Champ amplifier is quite bright. The SD-1 is placed after the TS9.

The resulting tone is quite tight and focused with a good sustain. “Focused” is the important word here, this is where two overdrive pedals put together differ from one higher gain pedal.

Here is a video where I show my clean tone first, then I switch the TS9 on, and then both pedals:

The amplifier was miked with a Rode NT-4 and recorded using a Boss Micro-BR. The recording was then transferred into Cubase 5 to optimize the volume and add a hint of reverb. The guitar used is a Fender American Classics Custom Shop Stratocaster fitted with Kinman AVn blues pickups.

Why isn’t my clean boost pedal increasing my overall volume?

I see quite a few google searches about “boost pedals” pointing to this site and I have had several questions about them not having the desired effect, so I think a short post about their use is in order.

To put it simply, there are three cases:

  1. The clean boost pedal is placed before your overdriven amp or your favorite distortion pedal: activating the clean boost will not increase the overall volume much or at all. This is because any overdrive or distortion is inherently compressed and levels the volume. It will instead increase the gain i.e the amount of overdrive/distortion. Before the arrival of high gain amps and pedals, a lot of guitarists used treble boosters or overdrive pedals to boost cranked amps in order to achieve big distorted tones. Brian May is a prime example.
  2. The clean boost pedal is placed after the overdrive of your amp in the effects loop or after your favorite distortion pedal in your pedal chain: activating the clean boost will increase the volume but not the amount of overdrive/distotsion. I recently wrote  a post about using a clean boost pedal and other solutions to boost the volume for solos in a live situation. For overdriven amps without an FX loop, it is difficult to increase the volume through a pedal. Any clean boost will increase the amount of overdrive and not the volume (see case 1).
  3. The clean boost pedal is placed before a clean amp: it will increase the volume and might push the amp into “break up” which is a slight overdrive, depending on how much clean headroom your amp has got.

As I pointed out in a previous post, the only way to increase the volume for your solos is to somehow put some form of volume control (clean boost, volume pedal, equalizer, etc.) after your overdrive/distortion. It does not matter if this overdrive/distortion comes from an amp or a pedal. A clean boost placed before will increase the gain, not the volume so much whereas a clean boost placed after will increase the volume.

For more information, you can also refer to my previous posts about effect placement and the difference between overdrive and distorsion.

How to use a compressor for guitar

The compressor is often seen as a bit of a mysterious effect. I will try here to enlighten those of you who think “why the heck should I be using a compressor?”. You will also find below a video demo showing what a compressor does to your guitar tone.

Studio Compressors vs Guitar Compressors

You have first to understand a little bit about how a compressor works. Compressors originated in studios as sound reinforcement tools. They are probably the most used studio processors after equalizers and reverbs. What they do is “reduce the dynamics range of a signal” i.e. the difference between the softest and loudest volumes. In simpler terms, when you feed a signal to a compressor, be it vocals, drums, guitar or bouzouki and the volume of this signal is louder than a “threshold”, the compressor will make it softer. The amount of reduction is governed by a setting called “ratio”. In that respect a compressor can do what a limiter does, there is a quite loose difference between the two. The original use of compressors was to avoid distorting recordings or radio emissions. But a compressor can also have the effect of augmenting the sustain by increasing the volume as the signal fades out (this is very useful with a guitar, more on that later).

The DBX 160SL is a reasonnably priced studio compressor

Beside “threshold” and “ratio” settings, there is also usually an “attack” setting (how fast the compressor kicks in) and a “release” setting (which can increase the perceived sustain). I will not really go into more details as this post is guitar oriented and studio compression is a very vast subject. Nevertheless, know that compressors are used in studios on almost every instrument as well as entire mixes to add punch, clarity, smoothness, more perceived volume, etc. If you are serious about making your own recordings, you will have to master the art of compression (see this MIX magazine article for further reference).

It is indeed quite an art to find the correct compression settings on studio compressors so that the sound does not appear too compressed i.e. so that the use of compression is transparent. On extreme settings, it will become more like an effect than a transparent sound reinforcement tool. It will generate a “squashed” sound which happens to sound pretty good with a guitar.

This is why effect manufacturers have put compressors into pedals, fortunately with simplified settings compared to their studio counterparts. They are also adapted to the dynamics and frequency range of a guitar and would not compare to their more versatile studio cousins in terms of sheer audio quality. The most famous of all compressors for guitar, the MXR dynacomp, has only two settings: output volume and “intensity” which controls the amount of compression. The more you turn it clockwise the more your tone will sound “squashed”.

The ubiquitous MXR Dynacomp compressor pedal
Where do I plug a compressor in the effect chain?

It usually goes at the beginning of the chain before overdrive and distortion effects. You can refer to my previous post about effect placement. If you look at a multi effect unit, you will actually see that the compressor is often first in the chain. I have also written a previous post about the unconventional use of a guitar compressor at the end of the chain in a recording situation.

And what does a compressor do to my guitar tone?

Used with a clean tone, a compressor will give you a bit of a “clicky” tone with lots of sustain. David Gilmour of Pink Floyd has been a long time user of compressors to get more sustain on his clean tone. He has used an MXR Dynacomp for a long time and is now using a quite expensive Demeter Compulator. Country guitarists make heavy use of compressors for their fast clean licks, adding an almost liquid quality to them. Funk and pop guitarists also use them to give some edge and volume consistency to their rhythm guitar runs.

Used before a distortion or overdrive, a compressor will be harder to notice as these effects already feature quite some natural compression. Nevertheless, a compressor can bring more sustain and fatness. Be careful about one thing though, by their very nature, compressors tend to add some hiss.


Here is an MXR Dynacomp compressor in action with my trusty Stratocaster and Fender Champ amplifier. I have set the OUTPUT and SENSITIVITY at 2 o’clock on the compressor which is quite high, the idea here was to exaggerate a little to demonstrate the effect. In the first part of the video, I show how it sounds with a clean sound. Note the “clicky” tone it produces as well as the increased sustain. In the second part, I show how it sounds used with a Tube Screamer placed after. Not so obvious to spot but it does fatten the tone and give it a little more sustain:

Short list of compression pedals
  • The MXR Dynacomp is a very common compressor and was used by almost everybody in the 70s/80s including David Gilmour.  It is still widely used by pros today. MXR sells two different versions: the modern one and the 76 reissue. The latter is a limited run and is meant to be closer to the early Dynacomps (and also unfortunately lacks a LED). I personally own a “modern” one from 1995. The Dynacomp is neither the most silent nor the most hi definition piece of gear but it has real character which is why it is so popular. Mine tends to be a bit bassy also which means the tone gets quite fat.
  • The BOSS CS-3 is a quite clean compressor but does not have much character in my opinion. I had mine modified with the Opto plus Monte Allum modification and it has turned it in an almost studio grade compressor.
  • Electro-Harmonix has several compressors in their line-up including the tube based Black Finger and the compact Soul Preacher.
  • The Keeley Compressor is effect guru Robert Keeley’s most popular pedal. This boutique compressor has quite a following now.
  • The Analogman mini-Bicomprossor is another powerful boutique pedal featuring two compressors in one (I don’t have one but it is no secret I am a big fan of Analogman’s stuff so it must be pretty awesome).
  • The Demeter Compulator is another high end compressor pedal, notably used by David Gilmour after he ditched his Dynacomp.

This is not by any stretch an exhaustive list as virtually every pedal manufacturer has at least one compressor in its range.

Hopefully this post will encourage you to experiment with compressors.

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