At the moment I am writing these words, I am very excited to know that you are one of the first people to assemble the kits we have designed, thank you very much for your trust and your perseverance!We have had this project on our hearts for 3 years and since only 6 months we have been able to invest enough time and resources to make it happen. I hope you really enjoy this experience and that you will be able to present your creation very soon. And, that we will have the opportunity to meet during a masterclass! before starting to assemble your ego driver kit technical documents If you are familiar with Do It Yourself with your effect pedals, you will find everything you need in this downloadable document.If you’re just starting out, the rest of the article is really made for you, so hang in there! Download this document anyway, you will need it to move forward and understand the rest of the events. Then you’ll see it’ s very useful. technical documents leave your soldering iron on for 2 minutes before assembling your ego driver The assembly of a FX Teacher kit has nothing to do with what you have already found on the net. Indeed, we have developed our own method to assemble your PCB, step by step, and to constantly check its proper functioning! And yes, we are committed to the infallible, but you also have some work to do so.So, in order for you to understand all the tricks we’re going to ask you to do, I suggest you to start by devouring all of our tutorials, if you haven’t already done so. Here they are, in order: read a bom learn how to solder wiring the jacks fx teacher analysis method disclaimer If you’re in trouble with a step or you don’t understand something, we will be happy to help you. For this, leave a comment with your request on this blog post. This project is even so DIY, so it is up to you to make your own decisions and responsibilities, and to check what you are doing before going ahead. You will be answered as soon as possible and this answer will allow other readers to go forward. Don’t be surprised if your comment doesn’t appear immediately, we have to validate it to avoid spam from certain robots. To recap, no emails, no chat, no calls regarding DIY, only requests on comments section please. Otherwise, it’s unmanageable for us.Please also check that your request has not been treated, also that your tensions are good and that you have followed all the steps 🙂 the fx teacher masterclasses If after receiving your kit, you feel that you need to be coached, you can always participate to one of our masterclass! The price of the masterclass includes the kit given on location, and the prestation. So if you have already received your kit, you can bring it back and pay only the difference!The masterclasses allow you to be supervised and to come home with a working pedal. But also to have all the necessary tools for the assembly, which can represent a little investment if you don’t have any material at home. sign up for a masterclass assemble the ego driver fx teacher kit the tools required You want to assemble your Tape Preamp by yourself at home, but you don’t have the appropriate tools yet? We propose here different tool packs, which we have selected, so that you can get everything you need to assemble pedals, cables, or both. our selection of tools the kit content In this FX Teacher kit, you will find inside the enclosure a bag 0 containing the PCB with the LED already soldered, and 7 bags containing all the components to assemble your pedal step by step.The content of each bag is detailed in the BOMs of each step, with indications on the placement of each component. PCB top side PCB bottom side The schematic of the Ego Driver bag 1: the power supply stage electronic schematic The power supply presented is not the same as for a Tube Screamer, for more headroom and a better filtering, we have added our personal touch! First, it is filtered by R22 and E4 and then when entering the TC1044 chip, it will create the -9V supply. The advantage is therefore to have +9 – (-9) = 18V of headroom. Then, we can feed our active circuits symmetrically!The usual method is unfortunately to center the signal on 4.5V to be between ground and +9V. It sounds much better with our method you’ll see! key points Here is a short list of points to be considered before soldering. All the tricks are in the blog articles mentioned above. Insert the electrolytic capacitors with the correct angle.Insert the diodes with the correct direction.Push the integrated circuit in the right side. the bom expected result Here’s what you should get after this step! voltage measurements Let’s go to the first test, nothing difficult here. You can solder a red wire on the 9V pad and a black wire on the G pad, which will allow you to supply the PCB with an FX teacher tester. Then, use a multimeter to measure the voltage between the -9V pad and the ground. You should read a voltage of about -9V, which indicates that the circuit is working properly. The value may vary slightly depending on the voltage supplied by your external power supply. Ours provides about 9.5V, so we read a voltage closer to -9.5V at the output of the circuit. If you don’t get the correct tensions at this step, you can check several points: if you read a voltage too low:make sure that the power supply you are using delivers 9Vcheck that you have not exchanged R13 and R22if you have no voltage at all:check the polarity of your power supply, and that you have not reversed the red and black wirescheck that the diodes are in the correct directionmake sure your multimeter is properly adjusted and connected correctlymake sure that you have inserted the TC1044 chip in the sockets, and that it is in the correct direction bag 2: the input buffer electronic schematic The first block that interacts with the signal is a transistor buffer stage. Here R1 is placed to unload any line capacity and avoid a “pop” at ignition. F1 and R2 form a high-pass filter that eliminates any continuous signal. The transistor is mounted in a common collector which allows a gain close to 1 in voltage and a significant gain in current. Its input impedance is highly dependent to R3. So we have a very interesting buffer. It is the same as the original Tube Screamer. key points Put the transistor on the right sidePut the resistors in the right order so that you don’t have to force to insert the last one the bom expected results voltage measurement The important voltage here is TP1 which is the polarization voltage of the transistor emitter. spectral analysis Now, connect the PCB to your audio interface following the FX Teacher method. You already have the footprints for the alligator clips on the board, you just have to connect the tester between the FX_IN and S1 footprints. The two black wires go to GND. The tester is in place, we’re ready to go. We’re going to create two stimuli: Sine of 1kHz to measure the gain of the circuit. Also, it will be possible to control the saturation rate of the system and notice the appearance of undesirable noise.Frequency sweep made of sine waves from 20Hz to 20kHz, in order to know the filter gain on each frequency! The expected result for this stage, with or without the effect, is only a 1kHz line with no harmonics (2kHz, 3kHz…). The spectrum must be completely flat because there is no amplification and we must preserve our signal. 1kHz on its own. No harmonics. Only a little bit of 50Hz captured by the measurement environment which is not perfect. We now generate our “sweep” with an amplitude close to -34dBFs, because it is an amplitude close to a guitar level.After measurement, we notice that all frequencies come out with more or less the same amplitude. To summarize, our input buffer stage is completely flat in the bandwidth (it does not filter any useful frequencies) and does not saturate when you inject a sinus. Perfect! Perfect! He does his job very well. Let’s move on! bag 3: the gain stage electronic schematic This first part of the gain block is made up of an operational amplifier or “OPA”.This setup is called a non-inverting amplifier stage, the gain in the bandwidth is theoretically calculated by the 1+(R18+GAIN)/R12 ratio.But all this depends on the filters created by R18+GAIN // C1 and R12 – F5. Then, R11 and F6 are used as a low-pass filter to accentuate the mids and cut the highs that are a little too strident ! With a cut-off frequency at -3dB of 7kHz. key points Set the potentiometer on the right side of the PCB, on the correct location and straight.Put the IC in the right way. the bom expected results frequency analysis In terms of connections, the input is always the same because the stages are cascaded. And, we are adding one stage after the other so the input will not change until we have finished assembling the kit. However, this time, measure the output at S2, which corresponds to the output of the gain stage. To understand how the gain stage works, we’ll start by putting our gain knob at maximum! Attention it will be necessary to lower the input level of the sound card until it is no longer saturated (when the vumeter is red it is necessary to lower until it is green). We thus obtain a beautiful bump between 400Hz and 2kHz. That’s exactly what you expect from a Tube Screamer! Everything else is attenuated. Except for the 50Hz that annoys us but that we won’t have once the pedal is finished! To know the gain (approximate and in the bandwidth) of the buffer + amp stage, we start by sending a 1kHz sinus when the effect is connected. We lower the input of the sound card so that it does not overload. For example, we note -7dB with our sound card setting. Then, a jack is connected between the input and the output of the sound card, without touching the input level potentiometer.This signal is injected again without modifying anything on the sound card, to obtain in this case, -41dB. For the calculation of the gain: Gain = -7 – (-41) = 34dB.It’s already huge! Pretty simple method, right? If you want to know the gain for each frequency you repeat the experiment but with a sweep rather than a pure sinus. bag 4: clipping and voicing stage electronic schematic At this point if you listen to your gain stage, you might be a little disappointed! Its harmonic content is not remarkable, it will only try to saturate the input of your guitar amp.We will therefore add clipping diodes, in order to cut the peaks of the sinusoidal signal and finally find them almost square!Each diode cuts more or less high in amplitude according to its threshold voltage. Regarding the voicing, you remember that the total gain of the amplification stage depends on 1+(R18+GAIN)/R12 (in theory, in the bandwidth).Here we will modify R12 by switching to R10 and the BASS trimpot with the voicing switch.Also, the bandwidth will be modified by choosing F4 at 1uF instead of F5 at 47nF. So we’re going to measure all this and discover our new spectral patterns for each of the possibilities! key points Solder the switches on the right side, solder sideMount the terminals in the right direction, with the holes facing upwardsPut the diodes in the right direction, look at the ring carefully the bom terminals Take the bag #7 and assemble the 3 small PCBs. There is one with the 2 LEDs, one with 2 x 1N4001, and one with 1N34 and 2x 2N7000. Be careful with the orientation of the components! For the diodes, there is the line drawn on the PCB, and for the LEDs, the longest leg corresponds to the + on the PCB. The 1N34 being rare, they are sometimes replaced by D9E. The D9E are recognizable because they have a blue ring drawn. These diodes have the same characteristics as the 1N34, but need to be placed ON THE WRONG SIDE of the diagram drawn on the PCB. 1N34 or D9E. be careful, the direction of the diode is not the same according to the diode you receive! Then place your favorite one in the diode terminal, and a capa in the capa terminal. In the team we prefer these: LEDs for the diodes, and 100nF for the capa! You can change them later to customize your drive. The small clipping PCB and the capa in the terminals. expected result spectral analysis For these measurements we use the same connection wires as the previous stage because we are located at the PCB input and at the output of the gain stage. The clipping is connected in parallel with the gain stage. So no physical modifications required. We measure the sweep and the 1kHz signal in bypass (jack connected in the sound card without the board): 2. Pedal connected this time and all switches switched up. We can start the measurements. The frequency sweep indicates that the bandwidth is now between 50Hz and 1.5kHZ. This is normal, when the voicing is at the top, it activates the branch that amplifies the basses! The pure sine at 1kHz create harmonics. We notice that the 1st odd harmonic (3kHz) has a greater amplitude than the even harmonics (2kHz and 4kHz). This is due to clipping distortion from the diodes which has this very particular characteristic and opposite to valves! As we might be led to believe. It is mainly the valves of our preamplifiers that will saturate following the arrival of large amplitudes in the mediums and thus finally create our even harmonics. 3. Clip on top and voicing in the center. Same configuration as a classic Tube Screamer. The sweep shows us a bandwidth between about 300Hz and 1.2kHz. So that’s what we love and expect from a Tube Screamer! 4. Voicing at the bottom and clipping at the bottom. We are now on the 22nF cap and on the diode pair of 1N34 and 2N7000 screwed on their respective terminals. The capacitor being smaller than the original one, 22nF versus 47nF, we expect to operate a bit more in the high frequencies. And, this is the case with a bandwidth that goes from 450Hz to 1.5kHz. However, the difference remains less significant than when you boost the bass.In terms of the differences in the harmonics of the sine at 1kHz, it is too small to notice it with this method. There you have to play and listen, ears are also very often excellent tools! bag 5: tone stack electronic schematic We start the Tone floor, a very important stage that allows us to find more or less highs at the output!First of all, you should know that we didn’t have a “G” type potentiometer. This “G” curve of potentiometers allows a very musical logarithmic progression at the mid-range level.We therefore faked it, by putting R19 and R20 in parallel of our B-type potentiometer, which offers a very similar result. To understand this layout, it is necessary to go to the 2 extremes of the Tone pot. Here are the equivalent diagrams when it is at the maximum and then at the minimum: Tone at maximum Tone at minimum When the pot is at full throttle, the gain created by the OPA depends on R16, R15 and F7. Knowing that R15 and F7 cut at 3kHz and that R16 is larger than R15, we amplify the high frequencies well. When the pot is at minimum, the gain is very close to the unit because it is equal to 1+R16/R1 or about 1.2. While at the input, the couple F7 and R15 form a beautiful low pass filter at 3kHz. We can better understand why aficionados are thrilled by a Tube Screamer Tone, we can gradually switch from a filter that cuts the high frequencies to a filter that amplifies them! key points Assemble the potentiometer on the right side of the board, solder sidePut the resistance in the right order, follow the BOM the bom expected result spectral analysis Start by placing the green wire at the output of the new stage, i.e. on slot S3. We keep the gain and volume at maximum, the voicing switch in the middle and then the clipping switch at the top.As we are on the same configuration as before, except for the Tone, we can take for reference in our measurements, the spectrum of the previous step as follows. (the one at the gain output with clipping at the top and voicing in the middle) With the tone at its maximum, here is what we measure: The peak is closer to 1.5kHz than 700Hz. With the tone at minimum: The peak drops to around 500Hz. This curve reflects the theoretical performance of the Tone stage, when the tone is at minimum, the bass and low-midrange frequencies are pushed out, while the high frequencies are filtered out. When the tone is at its maximum, on the opposite, we add trebles and break through the mix. So it’s up to you to find the right compromise that you like the most! bag 6: the output buffer electronic schematic And finally the last block! Almost identical to the one at the entrance. Its purpose is to adapt the signal after all the processing that has just been done to it. This way, it will be ready to pass without any problems to the next pedals! key points Solder the transistor on the right flipPut the resistors in the right order so as not to have to force the last one in. the bom expected results voltage measurements The important voltage to measure here is TP2. This is the polarization voltage of the output transistor. spectral analysis By putting the same settings as in the previous test and the Tone at noon, we should not change anything and have a similar result at the gain stage: One bump around 800Hz and we cut around it! okay, so what now? The most difficult part is done! Your board works perfectly, you will be able to transform it so that it fits perfectly into your enclosure and you can finally take it with you from everywhere. So we’re moving on to the final stage of assembly. You can also check out this article for more details on boxing. the footswitch pins First, take the 2×6 pins male connector in the true bypass bag. You’ll have to solder it to the board. Insert the side with the shorter legs into the board on the TOP side, as shown in the picture. Then you have to solder it, making sure it is straight. As for the potentiometers and switches, you can solder only one leg and check that it is correctly inserted, before soldering the others. the jacks Start by soldering the IN and OUT jacks, but don’t solder the power supply jack, we’ll do it later. For the IN, the black wire already soldered on the PCB goes on the bevelled side of the jack. Solder also the white wire between the TIP of the jack and the IN pad of the PCB. And finally a black wire on the RING of the jack, as on the picture. This configuration allows to isolate the ground of the circuit if no jack is connected to the input of the pedal.For the OUT, we only put a green wire on the TIP, which goes to the OUT pad of the board. No ground wire, it already goes through the metal enclosure, and we avoid a ground loop that could pick up noise. final assembly Once the jacks are soldered, we go on to the boxing! Check the washers and nuts before inserting the board, you should already have a nut screwed on each pot, so that they are at the same height as the toggle switches. Everything else will be used to assemble the pedal. Before inserting the board in the enclosure, we will first solder the power jack. Leave it screwed to the enclosure, otherwise you won’t be able to put it on once soldered. The red wire goes on the longest pin, then the black wire on the other one, and solder directly in the enclosure. Then, you can insert the PCB in the enclosure, then fix it, by putting a washer and a nut on the pots, and only a nut on the switches.Finally, screw the IN and OUT jacks, with a washer and a nut per jack. the true bypass On the small pcb, there are drawings that indicate the position of the footswitch and the resistor. Be careful to respect the direction of the pins of the footswitch, there are horizontal lines on the drawing that indicate the orientation. For the footswitch, it should be barely pushed in, so that it is raised and the pins are flush with the other side of the pcb, like on the pictures. You can then solder the resistor, the 2×6 female connector, and the footswitch, making sure that everything is straight. Finally, you just have to place the white plastic washer and a first nut on the 3PDT, then you can insert the bypass into the pedal, fixing it to the enclosure with the second nut you have left! you’ve finished to assemble your ego driver! You’ve finally finished assembling your Ego Driver kit! All you have to do is plug it into the amp and check that everything works properly. Then experiment with the settings, and additional components to change the clipping and voicing. You can also test with your own components if you have stocks of diodes and capas! We hope the assembly went well, and if you encounter any problems or have any questions, it happens below in the comments. Maybe you can find some help by reading them, or ask your own question.