Dinosaural OTC-201 Opticompressor  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
Post Reply
User avatar
aion
Solder Soldier
Information
Posts: 230
Joined: 22 Mar 2012, 00:12
Location: Des Moines, IA
Has thanked: 9 times
Been thanked: 472 times
Contact:

Post by aion »

Schematic attached! This is an original optical compressor design from Dan Coggins (Lovetone). Not very many were made, but it has nonetheless made it into the rigs of Ed O'Brien and Steven Wilson.

Full tracing log here, including photos of the process:
https://aionelectronics.com/blog/tracin ... ompressor/

There is also a PCB available here:
https://aionelectronics.com/project/con ... r-otc-201/
Attachments
OTC-201 schematic
OTC-201 schematic

User avatar
atalas
Information
Posts: 36
Joined: 24 Jul 2019, 21:22
Has thanked: 8 times
Been thanked: 27 times

Post by atalas »

Awesome work as always. Love the articles and pics.
Excited to see which other traces you're working on!

User avatar
bajaman
Old Solderhand
Information
Posts: 4549
Joined: 26 Jun 2007, 21:18
Location: New Brighton, Christchurch, NZ
Has thanked: 595 times
Been thanked: 2058 times

Post by bajaman »

great work - but the bipolar transistors are incorrectly marked on the schematic ?
cheers
bajaman
be kind to all animals - especially human beings

User avatar
aion
Solder Soldier
Information
Posts: 230
Joined: 22 Mar 2012, 00:12
Location: Des Moines, IA
Has thanked: 9 times
Been thanked: 472 times
Contact:

Post by aion »

bajaman wrote:great work - but the bipolar transistors are incorrectly marked on the schematic ?
Right you are, I got the original trace and the DIY version mixed up. I attached the corrected one.
Attachments
OTC-201 Opticompressor v1.1
OTC-201 Opticompressor v1.1

User avatar
atalas
Information
Posts: 36
Joined: 24 Jul 2019, 21:22
Has thanked: 8 times
Been thanked: 27 times

Post by atalas »

aionios wrote:
bajaman wrote:great work - but the bipolar transistors are incorrectly marked on the schematic ?
Right you are, I got the original trace and the DIY version mixed up. I attached the corrected one.
How crucial is the specific vactrol used? I think I have some VTL5C1 laying around, would the substitution for the VTL5C4 work?

User avatar
LaceSensor
Cap Cooler
Information
Posts: 585
Joined: 02 Jan 2011, 12:01
Has thanked: 57 times
Been thanked: 277 times

Post by LaceSensor »

Looks like its time to sell my original (!)

Great work, this is a really amazing compressor.

User avatar
LaceSensor
Cap Cooler
Information
Posts: 585
Joined: 02 Jan 2011, 12:01
Has thanked: 57 times
Been thanked: 277 times

Post by LaceSensor »

Ive had a Dinosural OTC-201 for a long while now - really an amazing compressor. Felt I had to build this.
Suffice to say I can cop all the sounds of the original. I am somewhat partially convinced that the pot tapers arent the same
My clone gets louder more quickly, in a comparative fashion turning up the level and sustain knobs. However, the levels match up at the extremes, so I beleive the pot values are accurate.

Overall, great project. I'd have loved to have availed of Aions fixing and enclusure kit, but alas out of stock. It did mean that I could use a really nice silver hammered paint enclosure I have been stashing for oooh 7 years...!

Enjoy pics.

Image

Image

Image

User avatar
pedalgrinder
Cap Cooler
Information
Posts: 548
Joined: 29 Aug 2011, 06:05
my favorite amplifier: Ampeg SVT
Completed builds: pedals with pots switches and everything
Location: South Australia Adelaide
Has thanked: 198 times
Been thanked: 172 times

Post by pedalgrinder »

I have one of these boards made it and i have never found a compressor i have been more happy with on bass this one is amazing hands down. My only complaint is this. I would like an led to pulse brighter on and low level pulsing in regards to how much it is compressing it doesn't have to spot on accurate but to give me some form of indication of its compression level via a led mainly on stage thats where thats handy can anyone lead me to a circuit or know of one i could add for this purpose. Thanks in advance. :?
What's the best thing about fat chicks and scooters? There both fun to ride around until your mates find out!

Post Reply