The Dinosaural OTC-201 Opticompressor is an optical compressor pedal designed by Dan Coggins, the chief engineer and circuit designer for Lovetone, and built in the UK under his Dinosaural brand1. It was produced in limited batches between 2013 and 2016, and Aion FX, who traced the circuit in 2019, estimated that probably only a few hundred were made in total2. The pedal is now discontinued: Coggins Audio states that "the now-discontinued OTC-201 'Opticompressor' lives on in a new guise: as the Thorpy FX 'Fat General' Compressor"3.
Who built it and how many were made
Dan Coggins is best known as the chief engineer and circuit designer for Lovetone, the UK company, and the OTC-201 was an all-original optical compressor design from him1. It was sold under his Dinosaural brand and built in the UK2.
Production ran in limited batches between 2013 and 20162. Aion FX's tracing journal put the total output at "Probably only a few hundred were made in total"2, and their project page describes surviving units as "exceedingly rare today"1. The unit Aion FX traced was from 2014 based on its serial number2. That scarcity makes the pedal an expensive find on the used market, and it is a large part of why the circuit has been documented and reissued in other forms.
Aion FX described the circuit itself in admiring terms: "in an engineering sense, it's a thing of beauty"2.
Bypass and controls
The original OTC-201 was buffered bypass, not true bypass1. That is worth knowing if you are comparing it against modern compressors, many of which offer switchable bypass, and it matters on a large board where long cable runs and many buffered pedals can add up.
When Aion FX released their Convex Parallel Compressor, a DIY project based on their trace of the OTC-201, they made two changes to the original design2:
- An internal slide switch to go between buffered mode and true bypass, a choice the original did not offer2
- The Direct/Blend switch, which on the original was elsewhere, moved to the face of the enclosure2
The OTC-201 is discontinued. Thorpy FX sells the Fat General Compressor, described on the ThorpyFX product page as "the critically acclaimed OTC-201 compressor" in a new form4, and Aion FX sells the Convex Parallel Compressor as a DIY PCB project for players who want to build the circuit themselves43.
The Aion FX trace and the Convex Parallel Compressor
The OTC-201 has an unusual place in pedal documentation history: it was the subject of the first tracing journal Aion FX ever published, back in August 20195. Tracing means working out a pedal's circuit from the physical board, and the OTC-201 was a hard one to do. As Aion FX put it, "The trace was complicated owing to the on-board hardware and hybrid SMD design"2, meaning the pedal combined surface-mount components with larger hardware mounted directly on the board.
That trace became the basis for the Aion FX Convex Parallel Compressor, a DIY PCB project released in August 2019, which reproduces the OTC-201 circuit with the added bypass switch and front-panel Direct/Blend control described above2. For players who want the OTC-201's approach to compression without hunting down a pedal that probably numbers only in the hundreds, the Convex project and the Thorpy FX Fat General are the two documented routes to it23.
If you are weighing the OTC-201 against other dynamics tools, the Compressor Pedals page covers how optical designs sit alongside other compressor types.
Questions
Who designed the Dinosaural OTC-201 Opticompressor?
Dan Coggins designed the OTC-201. He is the chief engineer and circuit designer for Lovetone, the UK company behind pedals like the Meatball and Big Cheese. The OTC-201 was an all-original optical compressor design from Coggins, released under his Dinosaural brand, and it remains one of the rarest pedals he has built.
How many OTC-201 pedals were made?
Aion FX, who traced the circuit in 2019, estimated that probably only a few hundred were made in total. The pedal was built in limited batches between 2013 and 2016, and surviving units are described as exceedingly rare today, which makes them expensive on the used market when they appear.
Where was the Dinosaural OTC-201 made?
The OTC-201 was made in the United Kingdom by Dan Coggins, the Lovetone chief engineer who designed it. The circuit used a hybrid SMD design with on-board hardware, a construction approach that made tracing the circuit unusually complicated, according to Aion FX's 2019 tracing journal.
Does the OTC-201 have true bypass?
No. The original OTC-201 was buffered bypass. When Aion FX released their Convex Parallel Compressor DIY project based on a traced OTC-201, they added an internal slide switch to go between buffered mode and true bypass, a feature the original pedal did not have.
What is the Aion FX Convex Parallel Compressor's connection to the OTC-201?
Aion FX traced the OTC-201 circuit and used that trace as the basis for their Convex Parallel Compressor, a DIY PCB project released in August 2019. The Convex adds a buffered and true bypass switch and moves the Direct/Blend switch to the face of the enclosure, changes from the original design.
Sources (5)
- Convex Parallel Compressor / Dinosaural OTC-201, Aion FX, 2019-08-04
- Tracing Journal: Dinosaural OTC-201 Opticompressor, Aion FX, 2019-08-03
- Coggins Audio, Coggins Audio (dinosaural.com)
- The FAT GENERAL, ThorpyFx
- Tracing Journal: Dinosaural OPA-101 Overdriven Preamp, Aion FX, 2020-11-16
