When looking to expand on the quality/type of our mic pre amps that we have available in our studio we found that our budget was too restricting to purchase something of high quality. We also like to have at least a pair of the same pre amp for any stereo recording. This got us thinking about the DIY route. At first it felt like a lot of prior knowledge of electronics was required but after doing some research into the basics and understanding the main components it became less daunting.
After researching into the different DIY packs you can get we decided to go with DIYRE. Their CP5 model, a 500 series pre amp with colour module slot, was affordable and getting good reviews. The thing that made this pre amp stand out was the ‘Colour’ aspect. Colour has been designed as a flexible, affordable option to add a range of different sounds into your chain through small modules (DIY Recording Equipment, 2019). As a small studio this idea appealed to us in terms of both space for outboard and budget.
CP5 Pre Amp
Our modules arrived nicely packaged with all components separated into small bags, numbered in the order we would need them. The design of the CP5 is very user friendly, you receive the face plate and knobs along with the PCB ready to be populated with the components and everything was clearly marked. The instructions on the DIYRE website were very clear and easy to follow, explaining which part was which. It would have been easy at this point to assemble the module without really understanding what each part did. As this was to further our skills as studio engineers and to gain knowledge of our equipment from a technical view point, it was important for us to have an understanding of what we were actually building.
To begin we laid out all the components and organised them into the order that we would be needing them. Using some card with slits cut at the fold was a useful way to sort out the resistors as these are very small with limiting defining features to distinguish between them.
A PCB is the starting point for assembling the module on. It is a ‘printed circuit board’ that electronically connects each of the components using copper foil which is etched with the desired points (conductive traces, pads) and then laminated onto a non-conductive layer.
A resistor is a passive device within the circuit. It is used to have control over the current and voltage within the circuit and also adjusts signal levels. They ensure the correct amount is being sent to the right path and can also be used to terminate a path.
A capacitor is made up of two metallic plates with an insulating (dielectric) material between them (Dahl, 2013). It stores energy in the form of an electrical charge created between the build up across its plates, (Electronics Tutorials, 2019). They are key components, influencing the behaviour of the circuit. Broadly categorised into polar and non-polar, they come with a variety of different characteristics which lend themselves to certain uses: storing electrical charges, blocking DC components, bypassing AC components and filtering unwanted signals. (Passive Components, 2017)
Once everything was organised it was like an electrical puzzle. Putting everything in the right place and making sure it was the correct way, then turning over the PCB and soldering the joint in place. Regularly trimming away the excess leads kept the board neat and easy to work with. Having had little experience of soldering prior to this project, it took a few goes to get the hang of it. Making sure to keep the soldering iron clean and not holding it on the same place for too long was key to getting clean solder joints. By the time we moved onto the second module we had a swift system of sorting, soldering and trimming.
Optical Disrupter Colour Module
We decided to go for the Colour-upter modules as we felt having a compressor of sorts in our recording chain would be a good addition. We had also been struggling to get a good bass sound previously and these modules were supposedly great for low frequency sources.
So what does it do? It is essentially an optical compressor that has been tweaked to result in asymmetrical distortion by removing the conversion to DC control voltage and instead sending the audio signal directly to the detector circuit (Houghton, 2015). An optical compressor contains resistors that are light dependent. The signal is fed to a lighting element which a light sensitive resister then reacts against. This then informs how the circuit will attenuate the signal (Messitte, 2018).
We decided to build both of these modules after the CP5 modules, so when it came to these we were more confident in what we were doing. We used the same organisation system as we had with the preamps and it didn’t take us long to have both colour modules assembled.
Inserting them into the CP5 was simple and quick. The slot is very clear on the CP5 PCB and you just click it into place. The one difficulty we had was the IC socket not being quite straight on one of the modules. We simply desoldered the joints and were more careful with the positioning when soldering it back on.
Seeing how quickly it all came together was great and if they sound as good as we hope then we’ll definitely look into which other modules we could get to interchange with the Optical Disrupter.
Overall the building process was successful with just a few mistakes that we were able to fix with the help of a desoldering pump. Both our pre amps are now set up and ready to be used. In our next post we will be testing them out and carrying out comparison recordings.
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Dahl, Ø. (2013). What Is A Resistor And What Does It Do? – Build Electronic Circuits. [online] Build Electronic Circuits. Available at: https://www.build-electronic-circuits.com/what-is-a-resistor/ [Accessed 9 Apr. 2019].
DIY Recording Equipment. (2019). The Colour Format. [online] Available at: https://www.diyrecordingequipment.com/collections/colour [Accessed 9 Apr. 2019].
Electronics Tutorials. (2019). Introduction To Capacitors. [online] Available at: https://www.electronics-tutorials.ws/capacitor/cap_1.html [Accessed 9 Apr. 2019].
Houghton, M. (2015). DIYRE Colour |. [online] Soundonsound.com. Available at: https://www.soundonsound.com/reviews/diyre-colour [Accessed 9 Apr. 2019].
Messitte, N. (2018). 4 Types of Analog Compression—and Why They Matter in a Digital World. [online] Izotope.com. Available at: https://www.izotope.com/en/blog/mixing/4-types-of-analog-compression-and-why-they-matter-in-a-digital-world.html [Accessed 9 Apr. 2019].
Passive Components. (2017). Capacitor Selection for Coupling and Decoupling Applications. [online] Available at: https://passive-components.eu/capacitor-selection-for-coupling-and-decoupling-applications/ [Accessed 9 Apr. 2019].
Zebb, P. (2017). South Bay Circuits | PCB Design, Manufacturing, Testing & Assembly | Blog. [online] Sbcinc.com. Available at: https://www.sbcinc.com/blog/pcb-vs-pcba-what-s-the-difference [Accessed 9 Apr. 2019].