Device Details


Name | Version: Twin Reverb 1.0
Author: OspreyInstruments
Device Type: Audio Effect
Description: The Fender Twin Reverb is a classic combo, but still a modern workhorse. It's bright and jangly top end is perfect for single coils strats, Rhodes, and a clean pedal platform. This is the amp sim I always wanted in Ableton.

Tonestack EQ:
Variations of the classic Bass/Mid/Treble Fender EQ have been copied by many different amp manufactures. Using only a handful of a passive components, this EQ's bands interact with each other when turning a single band's potentiometer. Through some circuit modelling and discretization, this was replicated using 3rd order IIR filters.

Tube Amp Modelling:
The tubes were modelled using fancy wavetables, developed from SPICE-like parameters. The preamp using two cascaded tube stages (12AX7 and 12AT7) and the power amp using a push-pull pair (6L6GC). Crossover distortion for the Class B power amp can be dialled in using the XOVER parameter. I used Jatin Chowdhury's implementation of the Jiles-Antherton equation to capture the saturation produced by the output transformer.

My suggested workflow is dialling in the EQ first, as it can dramatically shift the overall input levels (on the real amp, the EQ was also before the preamp stage, with only a single tube buffer before it). The INPUT control can add some makeup gain if needed, and be used to drive the preamplifier. The PRE control is more-or-less level compensated, so adjusting it primarily just adjusts the distortion. The power amp follows the tremolo and spring reverb the signal chain, but I thought it made more sense to keep it together with the preamp. The POWER control drives the input to the power amp section, and the OUTPUT control can attenuate the overall amp level prior to the cabinet convolution. There isn't a dedicated gain control to adjust the level between the power amplifier output and the transformer, so it is dependant on how hard the power amplifier is being driven. The hysteresis model does include a DRIVE parameter as well, so you will should get some milage out of that if you find the hysteresis is too heavy.

Optical Tremolo:
BAD FENDER! This is NOT vibrato!! The tremolo in this amp uses a optical cell (Vactrol) comprised of a light emitter and a photoresistor (light-dependant resistor). In earlier vactrols, an incandescent bulb or fluorescent panel was common, leading to a longer off-time than on-time, not to mention, some crazy nonlinear curves. A triangle wave is the most common LFO shape for these circuits, and seemed to be a good starting place. Through some pulse-width skewing, and creative filtering (LPFs and logarithmic envelope followers), I was able to approximate the sinusoidal-but-off-shaped attenuation curves in these older vactrols. This undeniably adds VIBE!! :)

Usage / Warnings / Bugs:
In terms of analog modelling, this is the most involved DSP project I have worked on to date. Owing to this, I cannot promise it will perform perfectly. I spent several days squashing bugs on my end, and I doubt I caught everything. If you encounter any major problems, please don't hesitate to let me know - I'll do my best to fix it. Even in its current state, I notice it's not perfectly behaved - it can emit noise when first loading or changing the oversampling factor. I added a 1.5 second mute on this parameter change, but I cannot guarantee this is sufficient on all systems (different load times across different machines)... so... watch your levels! (and have your track mute button ready lol)

To expand this further, I suggest adding some effects in front of the amp, such as:
-Echotron (from yours truly)
-Ableton's Tape Echo

Big thanks to the following people and resources:
Guitar(ix) project -
Jatin Chowdhury -
Schematic -


Live Version Used: 10.1.18
Max Version Used: 8.1.5
Date Added: Dec 27 2023 06:56:52
Date Last Updated: Dec 27 2023 06:57:24
Downloads: 0
License: None
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I'm not all that familiar with the original but I can say -- this sounds damned good to me! Thank you for sharing it
Very nice!
You weren't kidding about watching levels! It honestly sounds so good and there's so many features packed into one plug in, big fan. Might just put a limiter infront of it from now on haha.

(The noise cam through for me when I typed in a new amount for the bass setting and played a chord straight away if that helps at all)
Noob question - I just started messing around with this again and want to confirm - this is meant to be used last a send effect - correct? Far as I can tell, it's essentially all wet signal ("which wet" depending on the 3 levels but all are wet) - correct? Having fun dialing it in but started questioning my ears - probably time for a break!
edit: should say "used as a send" (ignore "last") in the message above

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