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Audio Blox: Experiments in Analog Audio Design

A Project page to host and blog about my various analog audio circuit experiments and designs.

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A Project page to host and blog about my various analog audio circuit experiments and designs. The "good" designs will get their own dedicated pages eventually and probably redesigned to be less hacky.

Audio Blox is where I will be publishing everything related to my analog audio design experiments and learning experience. Experiments/Designs that go well will be spun off into their own projects while others will live and die on this page.

Projects So Far:

Big Muff Blox

Big Muff Blox will be 4 PCBs deividing the Big Muff pedal circuitry across four PCBs. The PCBs will be design to plug into a breadboard for testing, experimenting, and analysis.

Boards Broken down to:

- Input Stage

- Clipping Stages (both on one PCB)

- Tone Stack

- Output Stage

Don Tillman JFET Preamp

Simple PCB implementation of the popular JFET guitar preamp designed by don Tillman. It will be a simple PCB with inputs for power, and connections for signal input and output.

Credit to Don Tillman for his design, nice website: http://www.till.com/articles/GuitarPreamp/


Treble , Mid, Bass Active Tone Control Block

This project is a bit more complex. Eventually some of these designs are going to need tone control. This project is my attempt to make an active tone control circuit based on this random schematic I found:

http://www.eleccircuit.com/three-circuits-of-preamp-tone-controls-by-ne5532/

PCB Route Pass 1:

The plan is to start by building a mono channel tone control based on the circuit but adjusting the values for the electrical guitar's frequency response.


Guitar FX Pedal Wiring Board

Newest project is a simple board for wiring up guitar FX pedals. The circuit and design are from mysticwhiskey on the madbean pedal forum http://www.madbeanpedals.com/forum/index.php?topic=3308.0 . Its a simple design that consists of a pair of 1/4 TRS jacks, a 3P3T switchm and an LED for power. I'm simply making my own version of the PCB that I can just order at will for my own projects.

Mysticwhiskey's design


Cousin Projects:

PiModulos - Custom Big Muff Pi w/ Mods PCB

A Custom PCB for implementing many variants of the Big Muff Pi Fuzz pedal with the options for some popular mods, initial prototype inspired by Skreddy Mayonnaise.

https://hackaday.io/project/7840-pimodulos

uPre - Electric/Acoustic Instrument Preamp with Tone Control

A simple custom instrument preamp orignally designed for my friend's churango, since redesigned with integrated PCB mounted potentiometers.

https://hackaday.io/project/7704-upre


DT JFET Pre BOM.ods

DT JFET Preamp bill of materials!!!

spreadsheet - 9.64 kB - 10/12/2016 at 20:08

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  • New Fangled tubes

    Adam Vadala-Roth10/24/2016 at 08:48 0 comments

    These new odd style tubes are interesting and given that a few people are building amps with them I figured I'd through my hat into the ring. Gonna go for a hybrid design microphone preamp with one or two of those tubes in use. Stay tuned more to come ! ;)

  • Parts!!!

    Adam Vadala-Roth10/20/2016 at 18:12 0 comments

    Today my digikey order arrived with parts for the DT JFET Pre. I'm going to solder up one and see how well it works with my component selection and board design. For the purpose of keeping my sweet Squire Vintage Modified Mustang guitar from being defiled, I'm going to mount the preamp in either a pedal enclosure or just solder up connectors. This preamp design (http://www.till.com/articles/GuitarPreamp/) is typically mounted inside the guitar as it has no controls for volume level or tone, it relies on the guitar's tone circuit. In the case of mounting it in an enclosure, it would just be a hammond box with no external controls, just power, in , and out all mounted with a PedalFX board. Stay tuned and follow the project to find out what I end up doing with it!

    Obligator Parts picture:


  • PedalFX - Guitar Pedal Interface board

    Adam Vadala-Roth10/12/2016 at 20:27 0 comments

    So a while back I mentioned I would be designing a PCB for making the process of taking and audio circuit and putting it inside a guitar pedal enclosure. The concept is inspired by the user mysticwhiskey, you can read more about his board in the project details section. The board is essentially the true bypass wiring that most guitar FX pedals use but as a compact PCB. My board is essntially the same except for moving the power input connector and using completely different components. My schematic is as follows:

    PCB:

    3D Views:

    Top

    Bottom:

    So its a fairly simple PCB but will make dropping these audio projects into guitar pedal enclosures super easy. The notch in the corner is geared towards aluminum hammond enclosures, this notch will allow the PCB to be tight up against the enclosure walls right in the corner maximizing space. The boards are gonna be made through OSHPark usng the 2 oz copper spec they offer, this will allow me to keep the board compact and make up for the trace witch limitations caused by the pad size on the 3PDT switch.

    OSPark Renders:

    Top Bottom

    Thats all for now until I get PCBs in the mail. Stay tuned on the DT JFET Pre build and check out my other projects !

  • DT JFET Pre Updates!!!

    Adam Vadala-Roth10/11/2016 at 23:28 0 comments

    Hey so its been a while since I touched this project but it hasn't been forgotten. A user on this site was very interested in the DT JFET Pre I designed within this project, so I got back to work on it :).

    So when I went to get PCBs ready to order I realized that the git commit with the finished board was never pushed. At the time I couldn't find where I put my laptop's backup so the board was essentially lost. I decided to redesign the board in KiCAD, its a little bigger but here it is:

    OSHPark Renders:

    Top:

    Bottom:

    So after doing a quick redesign I produced gerbers and did a quote with OSHPark to have it made. Around the same time I was ordering some other boards and found out that I had my laptop's backup on a flash drive when shuffling through files. So I decided to order both versions from OSHPark and they arrived today:

    Also in this update I have the bill of materials, which are viewable below and available as open document format in the files section of the project page. The BOM:

    SymbolValuePackageQuantityDigikey Part NumberManufacturer Part NumberPriceComment
    C14.7uF4X6mmCAP1493-10381-2-NDUMW1V4R7MDD1TP$0.36
    C2, C310uF4X6mmCAP2493-10354-1-NDUMW1C100MDD1TP$0.36
    P1, P2, P3, P4Header 2HDR1X24Header 2
    Q12N5457TO-92A12N5457-ND2N5457$2.19
    R16.8KR080511276-5320-1-NDRC2012F682CS$0.10
    R23MR080511276-5448-1-NDRC2012F305CS$0.10
    R32.2KR080511276-5290-1-NDRC2012F222CS$0.10
    R451KR080511276-5379-1-NDRC2012F513CS$0.10
    Total$3.31

    Its a pretty inexpensive build even including the PCB cost which were around 4 dollars each for a round of three from OSHPark. Now we wait on a digikey order to arrive and we're off to the races, stay tuned for more to come!

  • Tone Stack Progress and New Project

    Adam Vadala-Roth05/14/2016 at 19:02 0 comments

    Hey so since the last post I switched it up and did the custom tone control/tonestack I mentioned in the details section of the project page. So this tone control circuit is copied from the one I found on this page http://www.eleccircuit.com/three-circuits-of-preamp-tone-controls-by-ne5532/ . The tone control on that page appears to have been pulled from a solidstate stereo amplifier. The full schematic included Treb/Mid/Bass control for two channels with a volume/balance control between the two. The design I made extracts the tone control section, includes the input volume, and adds a unity gain input amplifier to the circuit. Below is the schematic:

    The schemtic went pretty quick, though finding all the appropriate components took quite a while. So this is the first pass on routing it, I'm still thinking about it incase anything additional comes to mind. I also need to adjust the input pin spacing to make it breadboard compatible. Anyways this design should be finished soon and off to the fab shortly. I haven't stated before but I will be using OSHPark for my PCB fab and possibly doing a lot of these boards as 2OZ copper boards, they are fast and quality for the cash. Below is the first PCB routing pass:

    So the new project is a small mini one and its not even my idea, its just a really great idea/design that I found years ago. Its a guitar FX pedal power, input, output, wiring PCB that makes building and wiring custom analog guitar FX pedals easy. The user that originated the idea is mysticwhiskey on the madbean pedal forums, http://www.madbeanpedals.com/forum/index.php?topic=3308.0 . He used that design in his custom delay pedal build, I have been planning to make my own version of the PCB so I can have a bunch on hand for future builds, now is the time. Here is mystic whiskey;s design:

    My design will be basically the same, he'll be credited on the PCB too ;), the only differences will be my component choices for the jacks, switches and other components. Stay tuned for more to come!!

  • DT JFET Preamp

    Adam Vadala-Roth05/11/2016 at 22:55 11 comments

    SO got another one for you guys today! The infamous Don Tillman JFET preamp is a design that has been kicking around the web since the early 2000s. I recall seeing it all over DIY guitar effects forums back in the day and even did a old design in eagle a few years ago but never fabricated it. Anyways I wanted to finally make a board and give it a shot, so here is my schematic and PCB:

    First Route of the PCB:

    All credit goes to Don Tillman for designing this preamp, I merely just copied the schematic to make this snazzy PCB. Check out his original page here: http://www.till.com/articles/GuitarPreamp/

    Stay tuned for more folks!

  • Let's Get Started: Big Muff Blox

    Adam Vadala-Roth05/11/2016 at 16:45 0 comments

    So before engineering/hackaday-culture became my life music was my main hobby playing guitar, drums, bass, and singing, in that order ;) I collected a lot of guitar equipment over the years but one of if not the most defining piece of gear I have is my Electro Harmonix Big Muff Pi fuzz pedal. I got this pedal because of my diehard fandom for The White Stripes and wanting to make music like that. Throughout my shortlived musical experience playing in bands in high school the Big Muff was at the centerpiece of my sound. With all that said, back to the engineering!

    So this initial project is what I call Big Muff Blox, unlike my PiModulos project which aims to be a general purpose Big Muff clone PCB this project is designed for experimenting and understanding the different stages in the Big Muff circuit. Big Muff Blox will be a collection of PCBs that contain each of the Big Muff fuzz stages like so:

    - Input Stage

    - Clipping Stages (both on one PCB)

    - Tone Stack

    - Output Stage

    So in short Big Muff Blox will be 4 PCBs deividing the Big Muff pedal circuitry across four PCBs. The PCBs will be design to plug into a breadboard for testing, experimenting, and analysis. With that I give you preliminary schematics for each of the boards:

    Input Stage Schematic

    Clipping Stages Schematic

    Tone Stack Schematic

    Output Stage Schematic

    That's all for Big Muff Blox, expect more over the next days but expect something different maybe later today, stay tuned!

    NOTE:
    I wouldn't be able to do this project and other Big Muff realted projects if it wasn't for this amazing website, check it out, this guy has everything there is to know about this circuit !
    http://www.kitrae.net/music/music_big_muff.html

    Circuit broken down and explained here:

    http://www.kitrae.net/music/big_muff_guts.html

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MachineHum wrote 07/06/2017 at 03:27 point

Very cool projects, I'm also obsessed with audio projects!

  Are you sure? yes | no

Adam Vadala-Roth wrote 07/06/2017 at 17:14 point

thanks!! I really need to get back to these, since they are all pretty simple and I actually have the funds to build them, one small problem I wanna port them all to KiCAD............... :)

  Are you sure? yes | no

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