Bill of Materials for Echo Base

I found all the parts I needed for this pedal. Most are available in the classroom, I found the rest of the components such as the PCB board, multiple IC's and specific transistors on Small Bear. I'm going to order the parts this week and start assembling it on a bread board next week.

I made three different lists. The first one is a list of all the basic components I need, and it mostly comprised of the components I need to buy. The second page is reserved for all the resistors I need, while the third is for the capacitors.

 

PT2399

The PT2399 is a delay/echo integrated circuit by Princeton Technologies. Although digital in nature, it is frequently used to emulate the sound of analogue (BBD- based) delay circuits by means of additional filtering. Its being found more often lately in a lot of DIY delay pedals.

http://www.diyaudiocircuits.com/tutorials/pt2399-digital-delay-analog-echo/

This link has a lot of useful information regarding this chip, and also has a link to the full and unabridged spec sheet, which is surprisingly hard to find online.

Echo Base Delay

The Echo Base is an analog-voiced delay with modulation, designed by Ian Maltby. It uses a PT2399 delay chip to create a sound similar to an analog delay,  but not as noisy and without the hassle of building a real analog delay. The modulation allows you to wobble the pitch of the delay around. This allows for tape-style “wow and flutter”, vibrato, and chorus sounds in addition to the delays.

The “tails” feature allows you to turn the delay off while letting the last few echoes die off, rather than cut off abruptly. This feature can be toggled on or off with a switch. Lots of useful modifications are possible with the Echo Base, and are shown in detail in the accompanying documentation.

The documentation and the PCB circuit for this pedal are available here:

http://musicpcb.com/pcbs/echo-base-delay/

This pedal seemed quite popular on all the forums as an accurate imitation of an analog delay, but not as complex and temperamental to build. I would reccomend it to anyone looking for a solid DIY delay pedal that comes with proper instructions. I also happened to listen to some of the sound samples, and it actually sounded pretty good. Ordering the PCB and all the other parts I need this week. If anyone has pedal housing unit or a cool looking box they can spare, let me know.

Midterm Schematic

This is the circuit I built for the midterm. Sorry about the blurry picture, that's the best my phone can do. I was initially going to add a delay section to this existing tube screamer circuit, but I've now decided to build a delay separately. This way I won't have any compatibility issues trying to match two different circuits, and can also add other touches to my delay such as modulation. I still want to finish this pedal later on as it wasn't too difficult and seemed like it would sound good.

Tape Bias, Homey

A little description thingamajig on tape bias!

Bias is a unique signal that is applied when recording on tape. There are two types of bias, AC and DC. Back in the good ol' days, DC was where it was at. The first recorders simply added the raw audio signal to the electromagnet in the record head. In other words, it is the direct current being added to the recorded audio signal. The problem with DC bias is that it results in poor low-frequency response and high distortion.

Later on, when people got their shiit together, AC bias was invented. This was a new and improved bias that resulted in less noise. AC is the addition of an inaudible high frequency signal to the recorded audio signal. This signal usually ranges between 40kHz - 150kHz. Bias increases the audio quality by pushing the signal into the linear zone of the tape's transfer function.

Vigen BBD project week 7 part 1

Hello All,
I have finally got my circuit to work and now I can begin to add the filter sections and tweak the circuit to get a better sound.  It currently is extremely noisy since their is no low pass filter and the voltage bias on the BBD and clock have not been optimized.  Setting the bias is not easy and requires some time and patience in setting up the circuit.  It is also a very fine tuning process since the BBD chip wants to see a very narrow range of voltage values.  This is why most of these types of pedals use a compander section to compress the signal voltage to usable levels and then expanding the echos upon reaching the output stage.  More details to follow.  I found a great website for DIY pedal building that provided a nice schematic, parts list and even a circuit trace for a functioning BBD-style delay pedal!  I will be analyzing this schematic and then continuing my circuit bread board.  Hopefully, I will be able to tweak the design to make my own version and to create an awesome analog delay pedal.  Here is the link to the resources and I will be posting some updates of my design here soon.

AD-3208
http://www.generalguitargadgets.com/projects/20-modulationecho/48-ad-3208

Edward

Vigen BBD project Week 6

Hello All,

So my BBD project is not working quite yet. There are many factors at play here, not least of which is the quality (or lack thereof) with regards to the bread boards. Here is a listing of the issues encountered so far:

Bread Board Issues

Bread boards can be notorious for having to get the parts seated right. This just means that as more parts are added to the circuit, you need to check and re-check every part to make sure it sits properly in the bread board.

BBD driver issues

I unfortunately, have not been able to get my BBD chip to work yet. Part of the problem here is the biasing needed for driving these chips. Whereas opamps, transistors and many other components have to be biased simple ratios like ½, BBD chips need a 14/15 ratio. In the older model chips, like the MN3005, MN3007 and so on, which ran on +15V, the newer chips like the MN3205, MN3207 and the one I am using, the BL3208, all run on +9V. I have still not isolated the proper voltage divider with simple resistors and in looking at schematics for most of these circuits, they utilize a carefully tuned trimpot resistor to bias the chip. Hopefully I will have this figured out by the end of the next class period.

Circuit Integration

Beyond these issues, most of the schematics available online for analog delay pedals are not correct or missing certain components. I have been able to find limited resources in regards to setting up the clock source within a circuit that is leveled beyond the simple schematic in the Stompbox cookbook. Datasheets for the clock driver are also very vague in regards to the test circuit, ie one is not provided, and I have been having to use the Stompbox cookbook as a reference.

I am at this point attempting to simply build the basic sections for the pedal such as preamp buffer, BBD section and then the pre and post filters. I have a working preamp buffer and I am currently working on the BBD section. I have attached photos of each section as well as the schematics of each section as built so far in a subsequent post. If I cannot successfully get the BBD to work by the end of class week 7, I will probably have to switch over to building my Alice microphone for time purposes and I so I have a completed project at the end of this class. The knowledge gained on this project has been very helpful but it is definitely not an easy project at all. There is reason why you pay high prices for analog BBD delays.

Edward

Here are the pictures of my circuit as well.

Hello fellow classmates and electricians,

Before you I have the schematic for the new distortion mod that I created in class. It is much different than the original schematic I posted earlier.  

With this circuit, I have created a multi-use circuit that does more than distortion. More details about it tonight....

Update on some shiii..

Just an update on what I'm doin.
I came in on Wednesday to work on some extra stuff, to add to my tape delay I built a preamp (left board) in hopes to replace that big honkin' preamp off of the tape player. It's just a simple circuit that our teach suggested I use. The right board is just the mixer that I made last week.
Welp..that's pretty much it!
Huzzah

Greetings fellow audio electronics-men,

This week, I have finally received my microphone in the mail today. This should be a fun build I can't wait to get started and to keep bugging Sudhu to help me out!

Self Oscillation circuit in the pedals

Hello All,
Here is a link to a thread I found had a couple of tidbits of fun information.

Self Oscillation Circuit
http://experimentalistsanonymous.com/board/index.php?topic=152.0;wap2

Obviously many delay pedals such as the MXR M169 Carbon Copy can be set to do this with no modifications.  However, it is quite simple to set this up in an existing circuit and the great nugget of information is the part about how to set the bias resistor to create feedback at shorter delay times and/or completely eliminate it.  Pretty simple stuff but just another thought of interest for understanding all the components going into some of these designs.

Peace,
Edward

Just some shiiit (not a resourse)

Howdy, just postin what's up with one of my projects. If you somehow didn't know what I'm doing, I'm doing an analog tape delay out of some old cassette players; a simple mechanism, but with some annoying little obstacles that shouldn't be too hard to tackle.. Anyways, here are some close-ups on what's been done so far:

As you can see from the first picture, so far we have our main player which is acting as our motor to move the tape with the record/play head removed for convenience to the far left of the loop. The second play head (6:00 of tape loop) will be acting as the "echo" head. What I am hoping to do is possibly make my own preamp to use in place of the large circuit board shown in the top left of picture 2 so that way it could use less real estate in the enclosure when that is made. I am planning on creating a simple mixer as well so some extra parameters can be controlled. The next step for now is figuring out how to create a line input into the delay so an instrument can be plugged into it.

Anyways, that's whats up with this. Woop!