Brelliott's TODP Tube Overdrive Pro Modular gets 3 additional alternative swappable Distortion / Clipping Boards

The difference between Dual and Single Diode arrangements is in the complexity and density of breakup - where you get a slightly thicker sound with Dual Diodes featured, Single Diodes results in a more open and typically brighter sound - with less saturation - they also seem to crisp up / crunch a little more . Each of the four featured boards  : 

• Original / Included  : Dual Schottky BAT85 Diodes [RoHS compatible]
• ALT 1 : Single Schottky BAT85 Diodes [RoHS compatible]
• ALT 2 : Dual Germanium D9A Diodes
• ALT 3 : Single Germanium D9L Diodes

...Sound quite distinct - and suit different types of music and different playing styles. Jonny has done an excellent job on these - those Diodes are very well selected and matched. I have a slight preference for the more richly textured breakup you get with the Dual Diode arrangements. And funnily I like the Dual Germanium and Dual Schottky ones about the same. The Germanium delivers that lush vintage-style grit, while the Schottky has an equally complex breakup - it's slightly higher gain / more saturated, with more sharpness and bite in particular. And the two Single Diode Boards - really mostly loosen up on the density of the Dual Diodes Textures.

The single Schottky kind of puts you in the frame for DOD250 style tones. The more textured Dual Diode boards deliver a slightly more sophisticated sound. I had a difficult time in picking an out and out favourite here. While I'm happy that the pedal now comes default with the Dual Schottky options - which as noted previously sounds better with the Fetzer Overdrive Board - so that's the one I used consistently for these tests tests. Obviously you ge more permutations with the full selection of boards at your fingertips. I have a place for each of those!

My core settings were FILTER @ 10 o'c, LEVEL @ Max, and GAIN @ 3 o'c. Then LOAD @ 220k, and the other 3 switches all in the down position - i.e. CUT @ 200Hz, BST @ 80Hz, and REC @ +12dB.

I had 3 different sessions with these - in an attempt to fully identify the specific patterns and characteristics of those types - while there are too many options to fully recall a full set of comparative values.

For each of those sessions I somehow ended up with a different favourite - initially the two Dual Editions, but then for the last Session the Single Schottky really vibed with me. I guess it depends on your mood and pattern of play as to which of those boards is preferable for each context. The exercise revealed that all the boards sound fantastic - as I ended up with several different favourites. With my most and least favourite changing with every session. If I had my choice per the time of writing this up - I might settle on the crisp, crunchy Single Shottky. All of those boards deliver something distinct and individual.

It will be interesting to find out what your own favourites are - once you get stuck into this super-versatile platform. Note that there is no disadvantage in the Schottky vs Germanium Diodes as they are just as vibrant, and harmonic and superior sounding on their own. Slightly more modern in profile vs the obviously more vintage-leaning Germanium Diodes. Turns out I actually like both Didoe types equally!

The above visual indicates Dual and Single Editions of Germanium and Schottky -loaded boards - identified by a double or single coloured band at the bottom edge of the board (as added by me for illustrative purposes) - Orange for Germanium, and Blue for Schottky varieties!

Jonny also encouraged me to test the Schottky's against the regular 1N4148 Silicon Didoes - and the two sounds nothing alike. The Silicon is warmer and smoother than the Schottky - and not nearly so hamonnically charged and textured.The Dual Schottky vs Silicon is very significantly different - almost chalk and cheese! While the Single Diode is somewhat closer - but still more modern sounding, sharper, more richly textured - and with slightly more bite and crunch - not quite as contrasting though as the Dual Schottky Arrangement.

So with the ability to swap Boards for both Distortion / Clipping and Overdrive - you have multiple variables in the mix - for an infinite upgrade path.

I'm still working on getting Jonny to modularise the EQ part of the circuit - while that will required a re-design to make the EQ also swappable via alternative boards - so currently the 'Filter' is an LPF - while you could have a Big Muff style Dual Filter Arrangement, or even a proper Tilt-EQ option once that part of the circuit is modular too!

Once the Overdrive, Distortion / Clipping and EQ elements are all swappable - then you will have the ultimate platform for Mods and Collaborations. I will be hitting up my buddies Markus Reeves, and Joe Halliday in particular to encourage them to collaborate with Jonny and design their own boards. To which ends Jonny will be bringing out some Blank Boards that you can DIY and Mod yourself. First he has some further projects to finish off - including the completion of several units of his GL3EQ BB, which include Allen & Heath circuitry in their mix!

The main TODP device goes for as little as £239 (or £259 with a Buffer - like mine!).

With that Standard model you get the Fetzer Overdrive Board Module (the middle one in the above visual), and the Dual Schottky Distortion / Clipping Board - both excellent - and perfectly complementary to each other.

The Fetzer Board for me produces the most satisfying tones for the Schottky and Germanium clipping options in particular - which is why I've used that one throughout this exercise. Handy therefore that those are the default included editions. The Fetzer generally and overall gets the most out of all those different Clipping Options.

There are 2 additional optional Overdrive Board Modules That you can acquire :

• The Purple Pentode Board is @ £65
• The Blue Pentode Mixer Board is @ £55

I marginally prefer the punchier, faster attacking / more reactive Blue Board!

You can then add as many of the Distortion / Clipping Boards as you wish - where they go for around £15 each.

So if you want to get the whole set (like me) - we're talking £239 / £259 (with Buffer) + 2 x OD Boards @ £120 and 3 x Distortion boards @ £45 - so what I currently have amounts to a total of £424 in overall value, which is of course a significant investment.

The original setup is amazing - and if you're growing this in stages - I recommend you get the Blue Overdrive Board next, and the Single Schottky one - and then build up from there. As noted - Germanium does not align with current RoHS standards and is considered a hazardous substance in Europe. There's kind of an internal market for those vintage devices - while they mostly ship to the USA these days where there are no active RoHS restrictions in place. Parts, however, do not fall under RoHS, so there should be no such restrictions.

These are super hi-fidelity devices, and really well priced.

NOTE - these are now fully available for EU Customers too - Brelliott now has an GPSR Agent to facilitate that.

All the options are listed out on the Brelliott Webstore!

I will be getting a second unit in May as I like permanently having the Fetzer Board in one of them, and will mostly have the Blue Triode Board in the other - and then split the 4 Distortion / Diode Modules appropriately. It will certainly come in very handy for the next bout of testing. It's always relatively tricky trying to compare different modules with just one TODP pedal - as it takes some time to swap those modules around - and you don't have that instant feedback loop of comparing one tone to the next!

I will likely do a further exercise once my second unit lands - where I can do more accurate evaluate head-to-head comparisons.