Showing posts with label Builds. Show all posts
Showing posts with label Builds. Show all posts

Tap tempo tremolo DIY: a complex project!

I am currently prototyping a tap tempo tremolo that I conceived. It is quite a big project, and I have been working on it since nearly 6 months now! Like many guitarists, I really like the warm vintage sounds that you can achieve using tremolo (like in "Bang Bang" from Nancy Sinatra), but also the choppy madness that you can get with square waves, like in "Know your enemy" from Rage Against The Machine, or even weird stuff with high speed tremolos... A really cool effect!

I play regularly in a band, and my point of view is that tap tempo is just absolutely needed for rhythmic effects like delays for instance. Thus, I decided to add one in my tremolo. It is not easy to implement a tap tempo, as you have to use digital circuitry, as we will see later... Here is my current prototype:
DIY tremolo with tap tempo
That is a lot of knobs! You can already notice that there are two footswitches: tap tempo (right side), and the true bypass footswitch that is a clickless relay bypass system! I used the relay bypass system that I conceived, which is completely silent, and more reliable than classic 3PDT true bypass. Indeed, 3PDT footswitches are the main reason for guitar pedal failure. The little switch in the middle of the two LED (bypass LED, and tempo LED) allows you to switch the pedal temporarily. This is nice to add some choppy stuffs while you play!

Black Arts Toneworks Pharaoh Fuzz clone

I want to make  Big Muff variants using my Coda Effects Big Muff PCB, and show you how to make them yourself. Lets start with the boutique version of the Big Muff that made it popular again on the stoner / doom scene: the Pharaoh Fuzz! Produced by Black Arts Toneworks since 2011, it was an immediate success because of the huge, warm, doomy sounds it can produce.

Here is my version:
Pharaoh Big Muff clone
As you can see, the Pharaoh has more controls than a classical Big Muff. There are the classic gain / volume / tone controls, like a classical Big Muff, plus a few other options. Here is the original version of the Pharaoh:
Black Arts Toneworks Pharaoh Fuzz
There are a "high" potentiometer that allows us to set the amount of trebles, and two switches. The first switch is a 'high / low' switch, that allow us to have 2 types of gain settings for the pedal: low gain and high gain. It modulates also a bit the trebles. Finally, you can choose the type of diodes in the last distorsion stage with the second switch: classic silicon diodes, no diodes or germanium diodes!
Black Arts Toneworks Pharaoh Fuzz clone
Finally, there are some modifications on the circuit. For instance, input and output capacitors are 10uF tantalum capacitors, which will let a looooot of bass go through the circuit!

Here is a gutshot (yes, I had fun drawing this!):
 Black Arts Toneworks Pharaoh Fuzz clone
You can see the tantalum capacitors that are drop-shaped. I try to avoid as much as possible to use it in my guitar pedals. They are not especially good for audio, expensive, and most of all there are not really "ethical friendly". Tantalum is produced from coltan, a mineral that is the root cause of many conflicts, especially in Congo. Illegal mines were opened without any regulation, degrading environment in an uncontrolled way, with many Human right issues (a bit of reading about that on wikipedia). Traceability is a big problem with electronics. Most of the time we do not know how, where or in what ecological context components are made... For tantalum capacitors, just know that they are easily replaceable by electrolytic capacitors.

Wima capacitors are much better for that: they are made in Germany (and thus, their production must respect European ecological laws and regulations). This is why I try to use them as much as possible:
 Pharaoh Fuzz clone
So, how can we make the Pharaoh from a classical Big Muff PCB?

Here is the schematic from the Big Muff page:
Pharaoh Fuzz schematic
As you can see, it is very similar to the Big Muff circuit! We can use the Coda Effects PCB and modify it following the above schematic. Here are the modifications to do:
- no mid knob, 470k for R5.
- no R2 resistor (we will use a switch instead)
- no D1/D2 diodes (switch here too)
- no R8 resistor. (replaced by a "high" potentiometer)
No big changes!

If you want, Rullywow sells a PCB especially conceived to make the Pharaoh Fuzz, named "King Tut". If these mods seems a bit difficult to do, you can buy this PCB to make it easier ! Rullywow creates really nice PCB, and this one is no exception, and is of very nice quality.

First, we will remove the mid knob by placing jumpers on the mid knob pads, like indicated on the build document.

To include the switches, we will have to use a 125B enclosure, it will not fit in a 1590B. We will have to use long lugs potentiometers to place switches so they do not touch the circuit board and create false contacts.

For R2 and D1/D2, we will use switches:
- SPDT on-on for choosing R2
- SPDT on-off-on to choose D1/D2 diodes.

Choosing R2: switching between the Hi/Lo setting of the Pharaoh

We use a "on-on" SPST. Signal arrives to the center of the switch, and goes through a resistor, 39k ("high" setting), or 390k ("low" setting):
Pharaoh mod
Try to make the connections on the other side of the PCB, it will be simpler. With this switch, you can choose the R2 value! In "high" position, there will be a lot of gain and trebles, whereas in "low" position, the sound will have more bass, less trebles.

It can apply to any resistor in the circuit, so feel free to experiment! Of course, some resistors are more interesting than others... I let you try!

Diodes choosing: 3 positions switch

We will use the same system for the diode switch. We are going to use a 3 positions on-off-on SPDT switch in order to have: germanium diodes (3 to have assymetric clipping), no diodes or classic silicium diodes. The second set of diodes to replace is D1/D2:
There it is! We have our two switches. Beware of false contacts with these switches: try to reduce the length of naked cables.Voilà ! On a déjà nos deux switchs !

Treble potentiometer

Last mod to add to have exactly a circuit like the original design: the treble potentiometer. In fact, you just have to replace R8 (tonestack resistor) by a 25k potentiometer. Just connect the lug 1 and 2 to each pad of the R8 resistor:
Pharaoh mod
It can also apply to any resistor! You can investigate to find your favorite resistor to modulate ;)
There it is! Voilà! We have got our Pharaoh Fuzz PCB!

You can solder the other potentiometers now.  Beware: if we use "classic PCB-mount" potentiometer, the switches will not fit in the enclosure (they will touch the PCB and create false contacts). We will have to use "long lug" potentiometers like this ones:
long lugs potentiometer
You can also use classic potentiometer and make the lugs longer with soldered wire with solid copper wire or cur resistors / diodes lugs for instance.
long lugs potentiometer solder

You can now drill the 125B enclosure, and rock! :)
Have fun!

To go further:
Official Pharaoh webpage : if you are interested in buying the original pedal
Veroboard version of the pharaoh: a bit annoying and complex to make, but doable!
King Tut PCB: dedicated PCB conceived by Rullywow

Dead Astronaut FX Chasm Reverb

Remember my Dead Astronaut Chasm Reverb PCB? I finally finished it! I left it quite a long time aside my bench, mainly because I did not have time or money to buy and build all the remaining things that needed to be done. Remember, if you want to have one, you can buy one directly from Dead Astronaut, or buy the PCB to make it yourself.

Here is my build: 
Chasm Reverb Prismatic dead astronaut
I used a prepainted enclosure, with a nice vintage color vibe, close to Surf Green color. With cream knobs of course! I just miss a cream pickguard part to have to most vintage fender look!

As I already said before, it was a fun build to make. The PCB is quite big and components are well spaced, so it is really easy and fun to build it, even for a beginner. I had absolutely no trouble at all. I did a few mistakes with the wiring, which is not a common wiring scheme as the pedal is buffered bypass. Apart from these minor incidents, the pedal almost worked immediatly, nice!
Chasm Reverb Prismatic dead astronaut

There are four potentiometers: volume (to set the output volume), mix (allows you to mix the dry signal with the reverb signal, you can go from a 100% dry to a 100% wet signal), damp (set the overall brightness of the reverb) and decay (set the amount of reverb that goes to into a feedback loop). Indeed, one of the features that make this reverb unique compared to other Belton Bricks reverb out there is that a part of the reverb signal can go through a feedback loop, allowing the reverb to auto oscillate! The switch allows to put the reverb in auto oscillation mode.

How does it sound?

I finally invested in proper recording gear (Senheiser e906 and external audio card), so I manage to record something for you! The Chasm Reverb is a deep, spacy sounding reverb, very good sounding with a delay!

The volume potentiometer is useful if you make it oscillate. At max, it is normal volume level, and you can lower it. The Mix is also quite useful, although I do not really like a too wet sound. The oscillation switch is really killer.

You can make the reverb smoother, and create "waves" of sounds, that lush for a quasi illimited amount of time! It is really awesome when combined with a delay! Perfect for ambiant stuff, and you can leave it on on the background.

Circuit analysis

Here is the circuit, from the build document:
Dead Astronaut Chasm Reverb Schematic
If you have already read the circuit analysis of the Rub A Dub Reverb, you can already find some similarities. As most of the DIY reverbs, it uses a Belton Brick, an IC that allows DIYers to make reverbs without having to use a spring reverb tank.

It is divided in several parts:
Dead Astronaut Chasm Reverb Schematic
Let's analyze each part of the circuit.

Power supply

The power supply is a classic one that we can find in many circuits. It provides 3 different regulated tensions:  9V, 4.5V and a regulated 5V.
Dead Astronaut Chasm Reverb Power Supply
The Zener diode (D6) prevents polarity inversions. R22 and C16 forms a low pass filter that will eliminate any 50Hz parasitic voltage ripples remaining from your AC outlet.

R23 and R24 forms a voltage divider that provides a 4.5V tension (VB). It is regulated by C17, a 47uF capacitor that will absorb excess of voltage. This tension is necessary for the OP amps to operate correctly

Then, there is a voltage regulator, REG1, that is a 7805. "78" means that the output tension is positive, and "05" is the output tension, 5V. The regulator is necessary to supply the Belton brick a good voltage. Unregulated voltage could result in damaging the IC that is very sensitive to higher or lower voltage drops, and so requires a regulated tension provided by this small chip that look like a transistor! You will find this kind of regulators in almost every circuit using numeric IC.

JFET switching buffer

This is a peculiar switching schematic that is very pratical here because it allows the use of a buffered bypass setting that make reverb trails possible. In a true bypass setting, the reverb would be cut abruptly when the effect is turned off, whereas here it can slowly decrease
JFET switching schematic circuit
So how does it work?

First, there is an input buffer, formed with R1, C1, R2 and the first OP amp of a TL072. As you can see, there is no resistor in the loop of the OP amp, thus it has a gain of 1. It is just used to transform the low impedance signal from the guitar into a low impedance signal.

Then, ther is the proper JFET switching. Here, JFET transistors are not used like amplifiers, but rather like "on / off" switches (like in computers!). When the JFET is turned on (by supplying 9V through the DPDT switch), it allows the signal to go from the drain to the source: the signal can pass. When a JFET is on, the other is turned off, so the signal either goes to the effect, or to the buffered output. A diode prevent any parasitic signal from the gate to enter in the signal path.

This switching scheme is nice with a reverb: it diminishes "popping" issues, and allows reverb trails, which is super nice with this reverb and its auto oscillating feature.

The Reverb circuit

The reverb circuit uses the Accutronics reverb module, a great integrated circuit that I presented already in the Rub A Dub Reverb circuit analysis.
Here is a schematic of the BTDR-2H that is used in this circuit:
Accutronics BTDR 2H Belton Brick
There are 6 pins on the brick. The two first ones are used for the power supply. Note that the power ground is supposed to be different than the signal ground. In some circuits, that is very important to separate digital and analog ground, and to combine them in only one point in order to diminish noise (especially if you combine digital chips with analog ones like MN3005 that are also in 5V).

The guitar signal enters in the third pin (signal ground on the 4th pin), and is "transformed" by the chip in a reverberated sound that goes out at the 5th and 6th pin. The reverbarated sound is not the dry sound + reverb sound. It is just the reverberated sound, so it is kind of peculiar. You have to mix it with the dry signal to make it sound like a reverb.

Here is the schematic of the reverb:
Dead Astronaut Chasm Reverb schematic

So first, there is a MOSFET input buffer, that increase a bit the signal. The signal is then split in two. A part of it stay dry (Dry signal part), and the other is treated by the Belton brick (reverb signal), they are mixed in the end with a mix potentiometer so you can set the amount of dry signal versus the amount of reverberated signal.

The dry signal just goes through this section without being modified, and goes to the mix knob.

The reverberated signal is buffered by an OP amp (TL072), with a gain of one (so no gain basically). A 100pF capacitors in the loop rolls off a bit of highs, and the signal can enter the BTDR2H brick. The signal then goes out from pin 5 and 6 of the reverb. The high are roll off by a low pass filter formed by the "DAMP" potentiometer and C5. For more infos about low pass filters, read my post about the Big Muff tonestack. Thus, you can set the amount of trebles in the reverbarated sound. Then, the reverbarated sound goes through an OP amp in a similar layout than at the entry. The signal then goes to the mix knob.

If that were the only features of the Chasm Reverb, this reverb would be a simple reverb with a tone control. What makes this reverb unique is its feedback loop. A part of the reverberated signal can go in the feedback loop and goes back to the entry of the reverberation circuit. The amound of signal going back to the begining of the circuit is set by the Decay knob and the switch that let you choose between a 47k resistor (a lot of signal goes back: oscillation) and a 100k one (less signal goes back: more a long-decay like reverb). This is really cool because if you set a high decay, a lot of signal can go back in the reverb circuit, and it can actually autooscillate! It also allows to approximately set the decay of the reverb, which is not possible with a standard BTDR2 brick.

After the dry and reverberated signal are mixed with the "mix" knob, there is another knob, that acts as a master volume knob. It is wired as variable resistor, and acts as a classic volume knob. The signal (reverb + dry) can now goes through the output buffer.

Output buffer

The output buffer is a simple buffer using a single OP amp from a TL072 chip.
Dead Astronaut Chasm Reverb schematic buffer
A 100pF in the loop rolls of a bit of highs. If the pedal is off, the dry signal goes through it with a gain of 1 (resistor R16/R13), but if the pedal is on, it has a bit of gain (R15/R16) to compensate the loss of volume due to the Belton Brick, the mix and volume knobs. It is a simple buffer, very transparent because of the high values of the coupling caps (C10 and C13, 10uF) and the use of the TL072.

There it is! I hope that it is clear and that it was helpful! Do not hesitate to ask questions in the comment. If you like this post, thank me by liking Coda Effects Facebook page!

To go further

JFET switching (pdf by Geofex): great explanations about JFET switching, around the classic Boss / Ibanez circuit.
Accutronics BTDR2 official webpage. 
Pedalrig tips about noise, great infos too!
Chasm Reverb official webpage, if you want to buy a built one or a PCB!

Jan Ray in a 1590B with Coda Effects PCB!

Here my latest version of the Jan Ray! This time, instead of the 1590BB or the 125B version, I made a smaller 1590B version, using a PCB that I designed! 

The Jan ray is quite annoying to make on vero, mainly because of the four knobs to wire. A PCB is thus quite helpful to make it easily. Moreover, it allows me to fit it in a 1590B enclosure. Here is the finished pedal:
Vemuram Jan Ray clone

I used the same look as before, with vintage orange sparkle prepainted enclosure, except that it is a 1590B now :)

 Make one yourself

It is quite a simple and fun build to do

Vemuram Jan Ray clone 
I also used a sticker to name it: Golden Hour (vintage overdrive). Photographers will understand! I think it gives a really nice look to this pedal. 

Here is the gutshot:
Vemuram Jan Ray clone
It is the classical circuit of the Jan Ray, with the OP amp, and trimpo for bass content / overall gain. I just changed a few things: R4 is 1.8k instead of 3.3k. This mod allows you to have low gain settings, nice if you want to use this pedal as a clean boost, or just to modify your sounds. Playing with the pedal, I realized you can "stratify" your sound easily by adding trebles and removing bass. Sounded very good with my P90 guitar.

Another modification I did was to replace the OP amp (LM1458) with a Burr brown OPA2134. I think it "soften" a bit the saturation. A nice touch to it.

I am currently testing other mods, with the diodes (LED, compressed...etc.), treble filter (to have less trebles maybe), gain of the last OP amp (too much volume for me on this pedal)

I just made a circuit guide of it to help you understand what does what. The Big muff page has this kind of circuit guide, and I find it very helpful. I hope that you like it, let me know what you think!
Jan Ray Timmy schematic circuit guide
If you want to experiment, socket the component you are interested in modulating, and try different values! Read the circuit analysis I made for more infos.

Sound samples !

LPB1 boost

Remember my LPB1 PCBs? I finally built one! As the PCB is quite small, I decided to make my first 1590A build. Here it is:
LPB1 boost clone 1590A
Simple one knob boost, with quite a lot of gain. I used a 2n5088, which provides already quite a lot of gain. It is a simple volume boost, quite transparent that can be used to make your amp saturate a bit more, or to simply increase the volume of your guitar if you use it in your amp loop.
LPB1 boost clone 1590A
This is my first 1590A, and everything went better than expected. I was afraid that I would not have enough space inside such a tiny box to make all the component AND the circuit fit, but it was OK.

Some advice to make it easier:
  • Use PCB mount 3PDT. They are a bit smaller than "normal" 3PDT and let you a bit more space.
  • Use semi-enclosed jack like Lumberg KLBM3 jacks. They are a bit smaller and easier to use than open jacks like the one I used.
  • use 9mm pots.
Madbean pedals has issued a very nice guide to explain you all the tricks and tips about 1590A builds (pdf). I managed to make it, not the most impressive 1590A build ever, but nice though:
LPB1 boost clone 1590A

How does it sound?

Well, it is a simple clean boost. So you can either use it as a volume boost in front of your amp (if set clean), or in the FX loop, or to increase the gain of your amp if you have set it crunchy. You can also use it before a dirt pedal to increase the saturation of it.
I am planning on testing it in front of different builds. I already tried it in front of a Jan Ray build, making it basically a Tim, nice to have 2 gains settings in one pedal. I also want to try it in front of a Big Muff, like in the Musket Fuzz... I think it can fit in approximately any guitar pedal!

Circuit guide

I already did a circuit analysis of the LPB1 booster. However, I realized that sometimes, it is easier for beginners to understand the role of each component with an infographic, like the circuit guide of the Big Muff page.
Here is the one of the LPB1 booster :
LPB1 circuit guide schematic

Let me know if you like this kind of representations, I can try to update old circuit analysis with circuit guides like this one!

Big Muff circuit going to fab!

Here is my new Big Muff PCB!Big Muff PCB
Remember when I was telling you about PCB development? (yes, long time ago...) I finally finished one! It took me a lot of time, but now I am satisfied with my layout:
Big Muff PCB layout
As some of you recognized, this is a Big Muff circuit! I decided to add an optional forth knob: the mid knob. I can decide whether I want to add it or not, simply by adding a jumper if not (and then, the tone potentiometer can be wired in the center of the pedal). Maybe I will add another optional feedback mod, allowing to connect Q1 emitter to Q3 emitter via a switch. It creates a nice noisy feedback, ideal for sound experimentations...

The circuit is exactly the same as a classical Big Muff, I just added the mid knob in the tone stack, and some components for polarity protection and voltage stabilization. (on the top-left part of the PCB) I will rename the components so their number will be the same as the one used on the Big Muff Page, so you can easily make any version of the Big Muff you like, or modify it with their great circuit guide.

Capacitors sizes were chosen bigger than needed, so they can be swapped with other value to fit any Big Muff model (Russian, Ram's Head, ...etc). Note the funky logo I made because OshPark is not able to use imported images...  Anyway, it is still nice!

I receive the first batch of prototypes:
Big Muff printed circuit board

It is a very compact build! It can fit a 1590B enclosure (well, I hope so...), or at least a 125B with top mounted jack. For now, I ordered a test batch of 3 PCB in oshpark, and I plan to test it as soon as possible! If it works correctly, I think I will produce a small serie of PCB.

    As you may know, PCB are cheaper if ordered in large quantities. If you are interested in buying one PCB (or more!), send me an email, so I can adjust the number of PCB I will order! Price will be around 5-8 euros for the first batch (depending on the number of people interested), with a 1 euro shipping cost for France, and 3 euros abroad.

I first designed this PCB for personal use, but it can be a win-win situation if people are interested.

For now, I am thinking about the logo I will use, I thought of this:
I noticed that the "Pi" symbol, looked like a lot a Dolmen... Which is also convenient for a Fuzz that has been used by many stoner guitarists, including ones disguised as druids (Sunn o))), anyone ?). Maybe I will have it laser cutted in black or red (maybe purple for a "violet era" rams head), in order to have 2/3 different version. A bare aluminium version with the red logo that will be the "vintage correct" version, following a classic 73 ram's head fuzz schematic, and a black logo on a black or dark green (russian) box for a "doomy" version, very bassy and gainy.

Let me know what you think about it, post a comment!