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 = 0.99999999 ;;; 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) (float-vector 0 -0.99))) (tank_1 0.0) (tank_2 0.0)) (do ((i 0 (+ i 1))) ((= i len)) (let ((sig (all-pass-bank input-diffusers (one-pole lp1 (delay predly (ina i *reverb*)))))) ;; add incoming signal to rotated tank: (set! tank_1 (delay delay_33_39 (all-pass diffuser_31_33 (one-pole damper_30 (delay delay_24_30 (all-pass modallpass_23 (filter dc-block-1 (+ sig (* decay tank_2))) (+ (smpls->samples 8) (* (smpls->samples 8) (oscil excursion_24))))))))) (set! tank_2 (delay delay_59_63 (all-pass diffuser_55_59 (one-pole damper_54 (delay delay_48_54 (all-pass modallpass_46 (filter dc-block-2 (+ sig (* decay tank_1))) (+ (smpls->samples 8) (* (smpls->samples 8) (oscil excursion_48))))))))) ;; tap reflections and output: (outa i (+ (* +0.6 (tap delay_48_54 (- (smpls->samples 266)))) (* +0.6 (tap delay_48_54 (- (smpls->samples 2974)))) ;;(* -0.6 (all-pass-tap diffuser_55_59 (smpls->samples 1913))) (* -0.6 (tap delay_59_63 (- (smpls->samples 17)))) (* +0.6 (tap delay_59_63 (- (smpls->samples 1996)))) (* -0.6 (tap delay_24_30 (- (smpls->samples 1990)))) ;;(* -0.6 (all-pass-tap diffuser_31_33 (- (smpls->samples 187)))) (* -0.6 (tap delay_33_39 (- (smpls->samples 1066)))))) (outb i (+ (* +0.6 (tap delay_24_30 (- (smpls->samples 353)))) (* +0.6 (tap delay_24_30 (- (smpls->samples 3627)))) ;;(* -0.6 (all-pass-tap diffuser_31_33 (smpls->samples 1228))) (* -0.6 (tap delay_33_39 (- (smpls->samples 27)))) (* +0.6 (tap delay_33_39 (- (smpls->samples 2673)))) (* -0.6 (tap delay_48_54 (- (smpls->samples 2111)))) ;;(* -0.6 (all-pass-tap diffuser_55_59 (- (smpls->samples 335)))) (* -0.6 (tap delay_59_63 (- (smpls->samples 121)))))) ))))) #| (with-sound (:channels 2 :reverb tank-reverb :reverb-data '(:damping 0.25 :predelay 0.03 :decay 0.7 ;; :decay 1.0 :reverb-decay-time 4.0 :bandwidth 0.75)) (let* ((input (make-readin "piano.wav")) (len (framples input)) ;;(len (* 3 44100)) (aenv (make-env '(0 1 0.9 1 1 0) :length len))) (do ((i 0 (+ i 1))) ((= i len)) (let* ((a (env aenv)) (rd (* a 0.5 (readin input)))) (outa i rd) (outb i rd) (outa i (* 0.2 rd) *reverb*) )))) (with-sound (:reverb tank-reverb :reverb-data '(:reverb-decay-time 3.0)) (outa 0 .1) (outa 0 .5 *reverb*) (outa 1230 -0.3 *reverb*)) (let* ((dur 3000) (s (make-oscil 10)) (e (make-env `(0 ,pi 1 0) :length dur))) (with-sound (:reverb tank-reverb :reverb-data '(:damping 0.0 :reverb-decay-time 3.0)) (do ((i 0 (+ 1 i))) ((= i dur)) (let ((sig (* 0.8 (oscil s (env e))))) (outa i sig) (outb i sig) (outa i (* 0.3 sig) *reverb*))))) |#
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