Hi all.
Tom Erbe visited us here in Oslo a week ago, and talked about
"Erbe-Verb" and other recent work he's done on reverbs. In his great
presentation he mentioned a paper by Jon Dattorro: "Effect Design #1"
describing a 'tank-style' plate-reverb amongst other things. I beleive
it was reverse-engineered from one of the early Lexicon digital reverbs?
I hadn't noticed the paper before, despite everybody else in the room
seeming to be familiar with it. Anyway, it sparked me into setting up
something similar in CLM/SND (attached).
Albeit somewhat slow, it sounds quite good with many different types of
input. The 'tank' is unity gain, so setting decay=1 creates a nice
'freeze' effect. See some suggested settings at the example calls at
the bottom of the file.
Note: there are 2 minor differences in the tap-section from those in
Dattorro's paper. I'll perhaps fix these later, if noone gets there
before me.
Currently only stereo. Should be easy to extend (to e.g. quad or FOA)
by setting up further sets of taps from the same tank. I'll perhaps do
more tests with this when i get time.
Have fun.
-anders
;;;
;;; tankrev.scm - 'plate reverb', Anders Vinjar 2016
;;;
;;;
;;; Dattorro style fig-8 tank-reverb, as outlined in paper:
;;;
;;; Jon Dattorro: Effect Design Part 1: Reverberator and Other
;;; Filters (1997)
;;;
;;; Paper available online:
;;; https://ccrma.stanford.edu/~dattorro/EffectDesignPart1.pdf
;;;
;;; PARAMETERS (+ default values presented in paper):
;;;
;;; FS=29761 Hz ; (AV: in JDs paper, see smpls->samples below)
;;; EXCURSION = 16 ; maximum peak sample excursion of delay
modulation
;;; decay = 0.5 ; rate of decay
;;; decay diffusion 1 = 0.70; Controls density of tail
;;; decay diffusion 2 = 0.50; Decorrelates tank signals; decay diffusion 2
= decay + 0.15, floor = 0.25, ceiling = 0.5
;;; input diffusion 1 = 0.750 ; decorrelates incoming signal
;;; input diffusion 2 = 0.6250
;;; bandwidth = 0.9995 ; High-frequncey attenuation on input; full
bandwidth = 0.
;;; damping = 0.0005; High-frequncey damping; no damping = 0.0
(define (make-diffuser siz scl)
(make-all-pass (* -1 scl) scl siz))
(define (make-mod-all-pass siz diffusion)
(make-all-pass diffusion (* -1 diffusion) siz :max-size (* 2 siz)))
;; tap from all-pass line, not used below
;; TODO: build 'reversed' all-pass-tap
;; (define* (all-pass-tap gen (index 0))
;; ((mus-data gen) index))
;; (define* (all-pass-tap gen (index 0))
;; ((mus-data gen) (modulo index (length (mus-data ap)
;; To be able to use prescribed taps and sizes in Dattorros article directly:
(define (smpls->samples smpl)
(let ((FS 29761)) ;orig. srate
(round (* (/ *clm-srate* FS) smpl
(define* (tank-reverb (predelay 0.0) (decay 0.5) (bandwidth 0.9995) (damping
0.005) (reverb-decay-time 1.0))
"(tank-reverb (predelay 0.0) (decay 0.5) (bandwidth 0.9995) (damping 0.005)
(reverb-decay-time 1.0))"
;; try setting 'decay = 1.0 for a nice 'freeze' effect
(let ((decay-diffusion-1 0.70)
(decay-diffusion-2 0.50)
(input-diffusion-1 0.750)
(input-diffusion-2 0.625)
(excursion (smpls->samples 16)))
(let ((len (+ (framples *reverb*) (seconds->samples reverb-decay-time)))
(predly (make-delay (seconds->samples predelay)))
(lp1 (make-one-pole bandwidth (* -1 (- 1 bandwidth
;; input diffusers = series of 4 all-pass-filters (mono input):
(input-diffusers (make-all-pass-bank
(vector (make-diffuser (smpls->samples 142)
input-diffusion-1)
(make-diffuser (smpls->samples 107)
input-diffusion-1)
(make-diffuser (smpls->samples 379)
input-diffusion-2)
(make-diffuser (smpls->samples 277)
input-diffusion-2
;; tank, fig-of-eight in Dattorro's figure p. 662:
(excursion_24 (make-oscil 1.0)) ;max 'Excursion' = 16 samples
(FS=29761)
(excursion_48 (make-oscil 0.707))
(modallpass_23 (make-mod-all-pass (smpls->samples 672)
decay-diffusion-1))
(modallpass_46 (make-mod-all-pass (smpls->samples 908)
decay-diffusion-1))
(delay_24_30 (make-delay (smpls->samples 4453)))
(delay_48_54 (make-delay (smpls->samples 4217)))
(damper_30 (make-one-pole (- 1 damping) (* -1 damping)))
(damper_54 (make-one-pole (- 1 damping) (* -1 damping)))
(diffuser_31_33 (make-diffuser (smpls->samples 1800)
decay-diffusion-2))
(diffuser_55_59 (make-diffuser (smpls->samples 2656)
decay-diffusion-2))
(delay_33_39 (make-delay (smpls->samples 3720)))
(delay_59_63 (make-delay (smpls->samples 3163)))
(dc-block-1 (make-filter 2 (float-vector 1 -1) (float-vector 0
-0.99)))
(dc-block-2 (make-filter 2 (float-vector 1 -1) (floa
