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Delay Pedal Project

10 March 2013

2013/03/10

After getting back into playing electric guitar more I decided I wanted to use modulation pedals more often in my playing, specifically delay pedals. Delay pedals are a lot of fun when playing alone because they can really fill up the empty space in your playing and make the sound seem “larger” than it actually is. Delay pedals are also very expressive for ambient music; less is more when it comes to playing with delay pedals I believe. They are also neat pedals when you want to get your post-rock on.

Instead of spending a bunch of money and time trying out and buying different delay pedals I figured I’d build my own. Also having not built a pedal in a couple years I figured this would be a good project to get back into pedal building, try out a few new things you know. I decided instead of designing my own circuit or breadboarding a bunch of circuits I’d have some fun and order some professional fabricated PCBs. With nice PCBs of well-known/sounding delay circuits I could build and tweak a few different delay circuits.

I decided to build three delay pedals as well as one reverb for good ambient measure.

The Neptune Delay
Multiplex Delay
Echobase Delay
Tenebrion Reverb

The PCBs are professional made with plated through holes, solder mask and silkscreen. The PCBs and designs come from various sources. All designs are original designs, though some draw on inspiration from other classic circuits. Through following the above links you can learn more about the circuits, controls, designers, etc.

neptune-delay-pcb

Neptune Delay PCB

multiplex-delay-pcb

Multiplex PCB

echobase-pcb

Echobase PCB

tenebrion-reverb-pcb

Tenebrion PCB

 

 

 

 

2013/04/01

As of now the PCBs are all populated and tested. I always enjoy installing the passive parts on the circuit board and soldering them all up. These nice PCBs made this task even easier and more enjoyable. The only thing I don’t like about professionally fabricated PCBs is how hard it is to de-solder components.

While testing all the circuits for functionality and sound I swapped a few components and it was a bit of a pain getting the solder out of the through plated holes. Luckily the amount of de-soldering I had to do was pretty small as all circuits worked right away. I slightly tweaked most of the circuits for sound, mostly filtering mods and LFO/modulation related mods.

The next step is deciding what enclosures these circuits are going in, what hardware they will use, how to drill the enclosures for the hardware and then all the finishing stages of the enclosure.

neptune-pcb-populated

Neptune Delay PCB Populated

echobase-pcb-populated-front

Echobase PCB (Front)

echobase-pcb-populated-back

Echobase PCB (Back)

tenebrion-pcb-populated-front

Tenebrion PCB Populated (Front)

tenebrion-pcb-populated-back

Tenebrion PCB Populated (Back)

multiplex-pcb-populated-front

Multiplex PCB Populated (Front)

multiplex-pcb-populated-back

Multiplex PCB Populated (Back)

 

 

 

 

 

 

 

 

 

2013/04/15

The enclosure for all four pedals have been drilled. It was a pain to fit some of these complex circuits into the small enclosures but in the end they all fit (though some are tight!). I think I did a good job spacing out the controls and making sure the controls weren’t too close to the footswitches. There is nothing worse than going to step on a pedal to turn it on and breaking a pot or knob in the process.

Next step is sanding the enclosures smooth to remove blemishes and imperfections. This allows me to get a smooth professional looking finish once I start painting these pedals. Once enclosure sanding is done I can start applying primer to provide the base coat for the colour paint.

delay-enclosures-drilled

Top Left: Tenebrion, Top Right: Multiplex, Bottom Left: Neptune, Bottom Right: Echo Base

delay-hardware-and-parts

Hardware, parts and PCBs for all the pedals.

 

 

 

 

 

 

 

2013/04/18

All the enclosures have now been sanded, primed and now I am starting to put the colour coat on the enclosures. Below is a picture of my makeshift paint booth. It is just a large cardboard box with the enclosures hanging from the top.

delay-enclosures-paint

Enclosures for the Multiplex Delay and Echobase Delay being painted.

I also decided to build one more pedal! I am also going to build a Zero Point Super Deluxe (ZPSDX) by Madbean Pedals. This cool delay pedal has a really nice fabricated PCB. It was sold out for the longest time and Madbean just recently got them back in stock so that is why I am getting the PCB now.

Check out the build document for the Zero Point Super Deluxe. It is a seriously cool versatile delay.

Super Point Super Deluxe

zero-point-super-deluxe-pcb

Zero Point Super Deluxe PCB

 

 

 

 

 

2013/04/30

Almost two months in and I have now got the last circuit built and working. The Zero Point Super Deluxe is a feature rich delay that I am very excited to play with more once I have it in an enclosure. The ZPSDX though very complex with its four filtering modes and on-board modulation went together with minimal debugging. The only issue I had with the circuit was a bad 5V regulator. The regulator which feeds the PT2399 delay chips wasn’t delivering 5V under load, the output voltage of the regulator was jumping all over the place.

Other than the faulty voltage regulator there was no issues with the ZPSDX. I did spend some time modifying the circuit though with the help of the excellent project documentation from Madbean. I performed mods for extended delay time, more range on the feedback control and louder repeats when the ghost switch is engaged.

Furthermore I decided to make the modulation toggle switch a footswitch. I still have the modulation switch on the PCB though. With a little modifying of the PCB and toggle switch I turned the modulation toggle switch into a switch that makes the modulation deeper and more chorus sounding; probably going to label the switch “Deep”. The “Deep” switch merely adds a large cap to the output of the LFO to add a bit more depth to the LFO’s modulation.

zero-point-super-deluxe-populated

ZPSDX PCB Populated (Front)

zero-point-super-deluxe-populated-back
ZPSDX PCB Populated (Back). Note the extra cap soldered on is for the “Deep” switch.
zero-point-super-deluxe-enclosure-drilled

Drilled enclosure for the ZPSDX. Note the added footswitch for turning the modulation on and off.

 

 

 

 

 

 

 

 

2013/08/12

I’ve been slacking on this project! The last few months have been busy ones.

I’ve committed myself to learning how to use Inkscape; a free open source graphics program. I must say I initially dreaded learning how to use this particular vector based graphics program but I am actually enjoying it now. It has been a unique learning experience. I am hoping to have all the pedals graphics (decals) completed shortly.

In the meantime here is the Neptune Delay’s graphic in progress…

pdf electronics inkscape pedal graphics decal delay pedal

The Neptune Delay’s graphics being created in Inkscape on a OS X Mac

 

 

 

 

 

 

2013/09/07

delay-project-finished

Family shot

neptune-delay-external

Neptune Delay

echo-base-delay-external

Echo Base Delay

multiplex-delay-external

Multiplex Delay

tenebrion-reverb-external

Tenebrion Reverb

zero-point-super-deluxe-delay-external

Zero Point Super Deluxe Delay

 

 

 

 

 

Half a year after I started this project it is now complete. It was a learning experience having not built a complete pedal in quite a while. I put off designing the pedals graphics for a while as it required learning how to use a new graphics program, something I was not excited about. Once I got the hang of Inkscape the graphics for the pedal’s decals came together fairly quickly. I am pleases with how the decals turned out on all the pedals. I ended up enjoying learning how to use Inkscape and I look forward to designing more graphics in it.

This project exposed me to finishing the pedals a different way than I normally do. Normally I use clear spray-on laquer to cover the pedals and protect them. This finishing technique never really satisfied me, pedals I built were never really that durable and the finish was prone to imperfections like cracking and checking. For this series of pedals I used Envirotex which is a pour on expoxy resin. The product is advertised as being as strong as 5o coats of laquer. Envirotex is the stuff used to coat bar tops to get that nice thick, smooth shinny durable surface.

This was my first time using Envirotex and it was a learning experience, the finish isn’t perfect but now I know how to improve it next time I build some pedals. That said the finish does look really good and is super durable, I am always looking for ways to improve the durability of my builds so Envirotex really impressed me.

Putting together the pedals proved to be fairly easy with the well designed PCBs I was using. Most of the boards had board mounted hardware so final assembly/wiring wasn’t too hard. Unfortunately for the Echo Base I created the decal with the labels the wrong way around. This forced me to not be able to use the PCB mounted pots and I had to resort to handwiring the pots to the PCB. This build’s internals ended up messy and I am not too happy with them. Oh well live and learn…

neptune-delay-internal

Neptune Delay Internal

echo-base-delay-internal

Echo Base Delay internal

multiplex-delay-internal

Multiplex Delay internal

tenebrion-reverb-internal

Tenebrion Reverb internal

zero-point-super-deluxe-delay-internal

Zero Point Super Deluxe Delay internal

 

{ 2 comments }

TC-15

15 July 2010

The TC-15 is a Trinity Amps version of a 15W Matchless DC-30 clone. The Matchless DC-30 is a very popular 30W boutique amplifier that is modeled after various Vox “AC” amps. The DC-30 is well known as a classic point to point handwired amp that recreates many classic Vox tones in one package.

The TC-15 takes the DC-30 but scales the output down to 15W by using two EL84 output tubes instead of four. The TC-15 also uses an eyelet board to build the amp off of instead of the somewhat chaotic layout of the point to point DC-30.

With two uniquely voiced channels and plenty of controls/switches the TC-15 is a versatile amp. I had played a few stock TC-15s before deciding to build my own so I knew just how good they were and how many great British tones they could produce. With this in mind I decided to build my own TC-15 but with a few tweaks and modifications.

Parts:

  • 1W carbon film resistors for the signal path
  • 1/2W carbon composition resistors for the plates
  • 2W metal oxide and 5W cermet resistors for the power supply
  • SBE 6PS Orange Drop capacitors
  • Alpha potentiometers
  • Cliff jacks
  • Belton tube sockets
  • Mountain switches
  • PVC wire
  • Accutronics reverb tank
  • Hammond choke and reverb transformer
  • Trinity Amps designed Heyboer made power and output transformer

Build:

Below are some pictures of the build. I tried to keep things neat as there was a lot going on inside the chassis wiring wise.  Lead dress was important with so many tubes and high gain signals running throughout the amp.

The build went smoothly though and the amp worked first time.

Design:

The TC-15 is a 15W and runs two EL84 output tubes in Class AB1 push-pull configuration. The amp has two channels, Channel 1 and Channel 2. Channel 1 uses an EF86 pentode preamp tube. Channel 2 uses two 12AX7 preamp tubes. The phase inverter uses a 12AX7 configured as a long tail pair. Finally a GZ34/5AR4 tube rectifier tube is used to supply the high voltage to the amp.

Channel 1 using the EF86 pentode features a Volume control and a six way contour rotary switch. The contour switch selects different coupling capacitors coming off the EF86 to provide six unique sounds ranging from thin, bright to full. The contour switch is used for simplicity and also because the output impedance of the EF86 stage is too high to drive a conventional tone stack.

Channel 2 uses two 12AX7s and has controls for Volume, Treble and Bass. Channel 2 uses a parallel triode input stage followed by DC coupled cathode follower to drive the Vox style tonestack.

In addition to the controls listed above there is also a Cut control which affects both channels. There is also a Master Volume that affects both channels to, it is a push-pull switch so it is possible to disable it. On the back of the amp there is two mini toggle switches. The first mini toggle switch labeled Crunch/Much selects between 5KΩ and 8KΩ primary impedance on the output transformer. This allows different loads to be presented to the EL84 output tubes and changes the tonal and distortion characteristics depending how the switch is set. The second switch is labeled Boost and adds a cathode bypass cap to the unbypassed cathode resistor on one of the triodes on Channel 2. This provides a gain boost across all frequencies and makes the amp a bit fuller and livelier sounding.

Cascade:

On Channel 2 the input stage is a parallel triode configuration. The parallel triode configuration allows slightly more gain than a single triode but not as much gain as two cascaded triodes. The parallel triode configuration also offers better noise rejection (very important for an input stage) and a slightly bigger fatter tone.

I decided to use a 3PDT toggle switch and wire it for Parallel/Cascade switch. When in Parallel mode the amp is completely stock. When in Cascade mode the two triodes are no longer in parallel but rather cascaded in series. The result of Cascade mode is a ton more gain and bite. Putting Channel 2 in Cascade mode is basically like putting the amp in overdrive mode.

The switch wiring is a little tricky and it took a while to get right. I had to control the amount of gain and make sure the amp did not oscillate because of the high gain/signal levels. It is very neat though to be able to toggle between Parallel and Cascade modes and hear the differences.

Reverb:

I thought a cool addition to an already harmonically complex amp would be to add reverb. I decided to add the reverb to Channel 2. I decided on Channel 2 because then I would not have phasing issues with the reverb signal and dry signal canceling each other out. This would happen if I added reverb to Channel 1. That said if you bride the inputs while plugged into Channel 1 you can get reverb with no ill effects.

Since I only had one noval socket to add the reverb I was physically limited to what reverb circuits to try. After much research and design I settled on a single 12AX7 reverb. The reverb circuit uses a 12AX7 tube setup in the typical drive and recover configuration as many reverb circuits are. A small Fender style reverb transformer is used to couple the tube to an Accutronics medium delay medium dwell reverb tank.

After much circuit tweaking I ended up with a very nice reverb circuit. I added a control on the back of the amp for Reverb Level and I also added a footswitch for turning the reverb on and off. Unlike some reverb circuits that can rob the amp of its original dry tone this circuit does not. When engaged the reverb adds a nice spacey effect to the amp which adds a lot of depth, makes the amp really fun to play. The reverb is not super intense and over the top like some circuits (Blackface Fenders for example). It is also not thin and “spanky” sounding but instead offers  a bit more midrange content and sounds a bit fuller.

The reverb tank barely fit inside the head cabinet and the wiring is very “busy” around the reverb tube socket but overall it was a worthwhile mod. I personally really like reverb on my amps so having it added to this already great sounding amp was a big bonus for me.

 Power Supply:

The power supply is unique in that the standby switch is a three position switch. In the middle position the amp is in standby mode. When the switch is put in the up position the amp is put into play mode with a choke in the power supply circuit creating the screen voltage node. When the switch is put in the down position the amp is put into play mode with a resistor in the power supply circuit creating the screen voltage node. Most amps either use a choke or resistor to drop some voltage in the amp and create a screen voltage and subsequent supply nodes. This three way standby toggle switch allows the user to experiment with a choke vs. a resistor in the power supply.

The choke provides a little tighter low end as it does not drop as much voltage across it as the resistor. The resistor has a larger voltage drop across it compared to the choke so with the resistor the tone is a bit grittier and not as tight. There is also slightly less headroom using the resistor in the power supply.

Other Modifications:

Other modifications to the circuit include the addition of a trim pot to control the amount of mids on Channel 2. The mod is done by replacing the 10KΩ resistor in the tonestack with a 50KΩ trim pot.

There is also a 850Ω trim pot in series with the 720Ω tail resistor on the phase inverter to control the gain/drive of the stage. This trim pot allows one to set the headroom of the phase inverter and essentially how quickly the amp distorts.

I also made subtle tweaks throughout the amp to control brightness and low end. Vox style amps can sometimes be a bit bright and loose sounding so I wanted to make sure I had just the right amount of high end sparkle with a solid bottom end.

I did find on the EF86 based Channel 1 the sound was a bit tight and stiff sounding without much bloom at first. I found that lowering the screen voltage made a larger impact on the compression, feel and tightness of the channel. With the stock 2MΩ screen resistor the screen voltage was 85V. With a 1MΩ resistor the screen voltage rose to 119V. The increased screen voltage caused a more pleasing tone, not as stiff with more compression and feel to the tone.

 

Schematic:

More schematics coming soon!

tc-15-done-reverb-schemtc-15-cascade-mod-schematic

 

 

 

Results:

 

{ 3 comments }

Overdrive Extreme Preamp

May 7, 2010

This is one of my preamp designs, I call it the Overdrive Extreme. It is designed to be a small pre-amp capturing the big tones of the Dumble ODS amp. The circuit is a mix of solid state (JFET) and vacuum tube. With many controls and features the tones are highly flexible.

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Top Drive Preamp

April 18, 2009

This is a new preamp design I have called “Top Drive”. Top Drive is a compact tube powered preamp that is quite unique and rocking. The preamp is voiced in interesting way,  the sound is very much like a classic Vox amp. The preamp has got that great top end “jangley” character with that nice […]

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The Hood Preamp

February 21, 2009

The Hood is one of my first tube preamp designs. The Hood evolved from my medalings with low voltage 12AU7 tube stompbox designs. The Hood is a low voltage preamp that uses two 12AU7 tubes, four cascaded common cathode Class A gain stages. The Hood is essentially a big glorified stompbox/preamp which offers a lot […]

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The Ultimate Boss CS-3 Mod

February 14, 2009

Ideology Behind the Mod: Another Boss pedal hits the chopping block! The Boss CS-3 compressor stock is just a terrible pedal in my opinion. It is incredibly noisy; I mean it has a ton of noise! Yes compressors are high gain and noise is to be expected from them but this pedal design seems excessively […]

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