Deep Blue Delay with TAILS mod

Update 03/2015: see this post for and alternative daughter board.

I have modded my Deep Blue Delay because I really think that having tails is an essencial feature for a delay pedal. I took the idea from the Merlin's Small Time Delay. By adding a FET analog switch at the input of the PT2399 we can bypass the input of the IC while getting the output in form of tails.

The analog switch is in a daugther board. Terminals A & B are interchangeable in the main and daughter boards. Using a DPDT on/on and a 3PDT footswitch we can select between buffered bypass with tails and True Bypass.

Using the layout by Mark the mod include adding a cut, moving one leg of a resistor one row down and moving one 1uF cap. The A and B wires have to be soldered in the middle of the board instead of on the side but there is enough room for them without moving other components.

This is the layout with mods.

This is the daughter board with the off board wiring.

I built mine without the volume mod, and this is how it's looking, with a few scratches on the paint but I like it.

In this pic you can see the daughter board next to the output jack.

Ghost Echo Reverb

This is my first reverb. It has a nice feature with the attack pot which delay the reverb effect. This time I used a bright led and tried a new paint work in the enclosure. This is my best enclosure so far. The layout is from Harald Sabro at sabrotone.com

You can see the belton brick under the board. I added a few colums to the board and soldered the belton directly to it and used jumpers to make the connections to the pins.

PC Timmy Overdrive

This is a really good overdrive with a lot of tonal options and different clipping settings. As usual, I took the layout from Mark at Guitar FX layouts. I'm getting better with my decals save from that little scracth near the footswitch.

Mictester Really Cheap Compressor

This is a really simple Optical Compressor designed by Mictester on freestompboxes.org. Go to the thread there to read more about it. I used the layout for the bass version by IVIark. This is my first 1590A enclosure and I really love how it looks, and how it sounds!!!

DOD-FX25

I really have an itch for envelope filters and this is my way of scratching it. The DOD-FX25 is an OTA based state variable filter with a basic envelope follower detector which started production at the begining of the 80s.

You can find a lot of information about it at page of Alex Petrini. He also has a simplified schematic and a PCB layout.

I couldn't find a veroboard layout for it so I made my own, and for my first layout I'm pretty happy with it. I couldn't avoid a couple of standing resistor and shared holes but if you are tidy it can fit in a 1590B box, although I would recommend using a 125B. I included a filter mode selector switch to select between band pass filter (original) and low pass filter. The low pass mode works very well with a bass. I also included a decay pot that helps to tame the long decay of the original design. This mod was suggested by Mark Hammer at diystompboxes.com, by including a resistor in paralel with C7 to ground we let it discharge faster thus shortening the decay time. By putting a pot in series with that resistor wired as variable resistor we can change the decay time.

This was also my first time working with a raw enclosure. I enjoyed the  drilling and painting and it came out pretty well (aside from the long wires).

Diamond Bass Compressor

I have read a lot of great things about this compressor.

This is the schematic traced by WhiteKeyHole on FSB.

The bass version has a switch to select the pivot frequency of the tilt EQ between 900Hz and 250Hz. There are no gut shots of it and I couldn't find the schematic or the component changes needed to build the bass version. The only reference I could find was from John Kallas at the Sabrotone post: (link)

I just raised the values of the 100n’s C7, C8,& C18 to 470n’s and slightly changed the frequency cap on the tilt eq.

From what I know, the only differences between the guitar and bass versions could be the changes sugested by John Kallas to eliminate the low end loss and the switch for the tilt center frequency, so I just needed to find how to configure the EQ.

The Tilt EQ

I found and article by Chu Moy on headwize.com (Designing A Pocket Equalizer For Headphone Listening) that explains the history of the Tilt EQ topology.

The guitar version of the Diamond Compressor use this exact configuration and component values (after C2) to get a pivot frequency of 900Hz with a 6db boost or cut on both sides of the tilt.

The only thing left was to find the component values to change the center frequency. I found a great article by Francesco Balena: Implement an audio-frequency tilt-equalizer filter; where he derives the transfer function for this eq design.

Using the next formula we can calculate the pivot frequency F_P:

Replacing the component values of the Diamond we get what is expexted:

This is the center pivot frequency for the guitar version:

Deriving M_L and M_H from the next formulas we can obtain the maximum low-boost asymptote as M_L (bass boost) and the maximum high-boost asymptote as M_H (treble boost).

We get this:

You take 20 times the log of M_L and M_H to get the response in decibels:

Wich yields a 6db boost and cut as advertised by Diamond.

I have simulated this filter in LTSPice

And we get the expected result

Note: I have used 47K for R_F in my calcs as it is the prefered value.

Changing the pivot frequency

We can change the pivot frequency by changing the value of C. Using 20nF capacitors we get an F_P of 251.37Hz, as you can see in the sim plot

To implement the switch as in the comercial version we can use a DPDT to select between two pairs of capacitors:

I have yet to build it, but I learned a lot studing this.

Configure your tilt EQ

I have implemented an on-line Tilt EQ Calulator to help you configure your own filter. Or you can use the next table if you want 6db bass and treble boost and cut.

P₁=50k, R=15k, R_F=47k

C	Pivot Frequency
20 nF	251,37 Hz
18 nF	279,30 Hz
15 nF	335,16 Hz
12 nF	418,94 Hz
10 nF	502,73 Hz
8 nF	628,42 Hz
6,8 nF	739,31 Hz
5,6 nF	897,74 Hz

You can even achieve an asymetric bass and treble boost. The next sim plot is what you get with: P₁=50k, R=33k, R_F=47k, C=6.8nF

Special thanks to:
Francesco Balena
WhiteKeyHole

Seamoon Funk Machine V2

I used the layout by IVIark with a buffered blend to mix some clean signal. This effect has some character, its only usable on a narrow spot of the Freq an Depth pots but when you find it this thing screams FUNK to your ears. I really like it because the envelope works as a reverse sweep, it sounds Awww instead of Waaa.

How do you get the DIY fever? (MusicMan Stingray 2-band Preamp)

I wanted a Stingray for cheap, so I bought an SBMM Ray4. I knew before buying that the preamp wasn't any good.

I needed a real Stingray preamp and I found the way to get one, building it myself. Bajaman at freestompboxes.org traced the schematic of the original MusicMan design.

UncleFluffy at talkbass.com started a thread where he offers the PCB's for anyone interested. He even uploaded his Eagle Cad files, and this is how I got my boards. I sent the files to Oshpark.com and received this.

After populating the components it looks like this.

I also shielded the control cavity.

Installed new knobs.

And my bass became alive, it now sounds really musical and has the sound I wanted. I still want to replace the pickup but that will come later.

And this is how I got the DIY fever. Once I have bought all the tools to mount my preamp the only thing I needed to build a pedal was to buy the components.

Green Russian Big Muff V7

My second fuzz, this one is famous among bass players and after building it I can see why, it has tons of low end.

I added a 47pF cap at the input to ground to kill the RF interference I get at home. You can see it at the bottom of the board, I actually socketed it just in case I want to take it out.

It was really tricky to squeeze the board in this enclosure, this is what you get when you buy pre-drilled enclosures. I had to order a dc jack that fits from the inside to be able to put everything in.

You can see the layout at tagboardeffects.blogspot.com.