Saturday, 17 December 2016

Bartolini Tube-It

Came across a schematic for this awhile ago as it seemed interesting. It's supposed to be a fairly rare overdrive pedal fetching up to $500. Here's some information I found about it:

The rare 1980s Bartolini tube-it Distortion Overdrive pedal made in Livermore, California, USA. Makes any amp sound like a Marshall. This may be the only pedal Bartolini ever made. Three position switch for more or less overdrive -- plus treble, bass, sustain and output controls.

It was designed to emulate the distortion characteristics of an early 80s Marshall JCM-800. Probably made in the mid 80's. Three way boost switch unloads tons of gain from mild to overkill. The circuit is set in a giant block of epoxy so there are no clones or schematics available.

Does anything from smooth, cleaner OD to straight up blistering, sustaining lead tones. Has the three way boost for different tone styles. Can do TS-9, Marshall, or its own thing all together. Controls include bass, treble, sustain , and output.

Whip the bottom off the tube-it and inside there's a little trim pot for adjusting the sound to be bit more, or less present. All models may not have this option. The trim is a small plastic wheel (see photo in the Disqus section) similar to the color to the exterior paint job.

Some of the tube-its were said to be mercilessly treble boosted. The pedal can get a sound like a healthy Tube Screamer in the first position. Now up the boost one notch, to add a little more drive, and fullness.

Perfect for lower output pickups. Need some grind? Just flip the boost switch to position three. It's at least double the increase in gain, as between positions one and two. The circuit is now presenting significant drive, and a fuller, slightly distorted tone. Let's not forget the absence of tone suckage when it's not kicked in. A very fine, versatile pedal.

The only thing I changed was make the high low switch 2 different switches so you can control each one independently.

Monday, 12 December 2016

Tube-Town Effects

Here is a serie of tube effect pedals by the German Tube-Town which were requested a while back.
There aren't videos available but you can find all infos, schematics and pcbs on their website here.
(The Pepper Shredder has been discontinued but it's supposed to be a tube distortion based on the Twin Valvecaster)

Saturday, 10 December 2016

Fuzz Central Liquid Drive

Came across this the other day and since I'm in the mist of finals I figured it would be a nice way to get my head away from my work and relax. Basically this is just a modified Ross Distortion, but has enough differences that I feel warrant a layout of its own, plus not sure how may people have seen it before.

List of differences from the source:

  • Time for a Better IC: After "auditioning" the single OPAMPs, I've decided to use a good 4558 in the Liquid Drive for better all-around sonic performance, in this case a Burr Brown OPA2134PA. You can also try all the other 4558-types, like the JRC 4558D and 4558DD, Burr Brown OPA2604, Texas Instruments RC4558P and several others.
  • Stabilizing the IC: Since this circuit utilizes a dual IC, but actually uses only one of the two internal amplifiers, we need to stabilize the second unused amplifier. In order to do this we'll tie pin 5 (non-inverting input 2) to ground, and attach pin 6 (inverting input 2) to pin 7 (output 2).
  • More Treble Response: For more treble response in the circuit, specially tailored for my modified Fender Telecaster and Twin Amp, I changed the 10nF input capacitor to a smaller value, in this case a 3.3nF.
  • Asymmetric Clipping Diodes: I personally prefer the sound of asymmetric clipping. For the Liquid Drive I chose to use 1N270 Germanium diodes for their warmer, more throaty response compared to Silicon diodes or LEDs. They're also a little more squishy and compressed sounding than Silicon diodes or LEDs, which makes them sound more like tube distortion to my ears. Using asymmetric clipping also enhances the harmonics and boosts the output of the circuit. The only drawback is that the drive range is decreased a little, but we'll make up for that in the next mod!
  • More Gain: In order to recover the gain range lost by using asymmetric clipping, I've lowered the 4K7 resistor on the 3rd lug of the "Drive" pot to 3K9...not a drastic change, but it does increase the available drive range.
  • More Low-End Response: To get a little more low-end response out of the circuit, I increased the value of the 47nF capacitor that's attached to pin 2 of the IC to 68nF.
  • Increased Output Level: In order to get a little more output from the circuit, I've used a 100K linear taper pot for the "Level" control. The linear taper pot will allow more output sooner in the rotation of the pot, as opposed to a standard audio taper, where all the useable output is in the 2 o'clock to 3 o'clock range. The linear taper takes some getting used to, but I think it's better to have that extra output sooner in the rotation range. The linear taper pot is LOUD at 11 o'clock.
  • Use Non-Polar Film Capacitors Instead of Tantalum: In order to get more clarity from the circuit, I've replaced the two 1uF Tantalum capacitors with 1uF non-polar AVX boxed metal film. They're larger than the tants, but I think their better sound quality is worth making a little more room on the circuit board for them.
  • Power Supply Filtering and Polarity Protection Mods: To add some extra nose rejection and polarity protection to the circuit, I've added a 100-ohm resistor in series with the power supply before the power makes it to the circuit, and then I added a 100uF Electrolytic and 100nF Cermaic capacitor in parallel with the power supply after the series resistor. These two added capacitors provide superior noise/hum rejection for the circuit. I've also added a 1N4002 diode in parallel with the power supply after the series resistor to help prevent damage to the circuit in case the battery or power supply is connected in reverse polarity. To some these extra parts may seem like overkill, but to me they're piece of mind :)
In the end you can try different diodes and Dual Opamps and see what you like best. I know I'm not the only one that's a big fan of the DOD250/MXR Dist+/Ross Distortion for it's great tone, simplicity, and the ease at which it can be tweak to your liking.

BYOC Confidence Booster

The BYOC Confidence Booster is just a simple linear boost and buffer. The only change i made was moving the trimmer offboard to make a pot. Figured this would be a nice easy project for those that want to get started building pedals.

Tuesday, 6 December 2016

Carl Martin Crush Zone

Here is a simple distortion pedal by Carl Martin.
Original FSB thread and schematic available here.

Thursday, 1 December 2016

Hudson Electronics Broadcast

Original info:
The Broadcast is a transformer coupled, discrete Class-A germanium pre-amplifier based on the classic broadcast consoles of the 1960s. In the low-gain setting, the Broadcast can cover everything from sparkling clean boost through to transparent overdrive, all with a healthy dose of volume available to push your amp. The Broadcast features a specially selected Triad steel-core transformer and a NOS germanium transistor. Advancing the gain on the Broadcast starts to saturate the transformer and the pedal’s discrete circuitry, giving rise to a gentle and dynamic compression coupled with subtle thickening of the midrange. With the gain switch in the high setting and the trim control wound up, the Broadcast starts to deliver heavier distorted sounds with a warm and fuzzy edge to them. The Broadcast covers a wide range of driven and distorted tones whilst remaining dynamic, responding well to pick attack and the subtle nuances of every player.

Thanks to Tipunk777 for reverse-engineering his own pedal in the Forum section.
There are 2 layouts:
one with a 24V charge pump and one without.
23/12/2016 Layout updated! Changed Gain Switch to On-Off-On and rotated OC71 180 degrees
Added a second layout with charge pump. It's the same as before but on the top of the layout to give more space to the transformer.