*** NFB resistor can double or triple in value for a Wet signal boost so that mix levels can maintain Unity whenever selected FX Loop is engaged, dependent upon user's Dry/Wet mix setting, and may require an adjustment of "Lead R33" to bring the mix up to unity depending upon the gear connected. That resistor's actual value must be determined by the desired mix of signals and how close to Unity Gain NB: Use an EQ/Clean Boost AFTER your delay in is desired for the Dry signal. In other words, the loop to resolve volume losses otherwise the user must balance the two signals both unachievable with the opamp stages, especially if at the FX MIX control knob, FX MIX opamp employing a Dry-Kill signal back to the amp, NFB, and here. NB: "Lead R33" 22k = unity otherwise a blended signal back to the amp will Dry/Wet. "Rear R39/41" 10k = unity Return. negate the need for calibrating any of the opamps "Lead ICa" linked = unity Send. Mix ratio at on this amp. In other words, Option A will suffice in "5" on "FX MIX" is 50/50, etc. that scenario. Option B: Remove cap for a full freq. boosted signal to parallel mix. Loop A *** 20k Unity gain Link ? @ -10dB remove IC2: replace with a socket and install OPA2134A or other better spec'd dual opamp with a better slew Loop B Send rate, especially if using time-based effectors for optimal results. Unity gain @ +4dB OPTION A: Unbal ground lift. One part pull and link will suffice. Doing this removes audible hum and sets the output signal to unity gain. Loop B Return * Option 1: remove R19 and replace with a 22k 1W Metal Unity gain Link Film + B100K variable @ -10dB resistor for a variable Negative Feedback control for a range of 22k-122k. Or, ** Option 2: tap off for better signal integrity W5 (16ohm) rather than W3 (4ohm) for over carbon pots, install a an alternative tone. switch for a 22k (JCM800), Option availible This may be put on 47k (JCM2000), and 100k to remove. a switch, too. Use (JMP), all Metal Films. stranded copper Raise Wirewound Resistors off wire for best results. board for good air circulation. Unity gain @ 4dB The Vesperado mod. Smoothing cap removes harshness from clipping zener diodes, otherwise this is the NFB peaker. Remove for optimal spring fidelity. Accutronics USA 4BB3C1D Two-Spring Tank, fully shielded and EE to chasis for EMI/RFI rejection ** Pin 2 provides rail a ground when NJM2121D, provides ** TR1 is off as the wider bandwitdh and second input is not better slew rate in use Remove. Coupling cap NB: Some boards are fitted Peaker cap: increase value for lower with a 220k. Make 92k. mid freqq., decrease for higher. Or remove for natural spring tank tone. Remove treble bleed cap, unless reverb is Increase value for too bright for more Bass freqq. taste, then try processing 220p or there abouts; this will effect all channels. Zener diode pair used to clip the signal and adversly color the sound. Remove them. Issue 3 is devoid of them, same with C6, C13, and R4. * Remove Main TR3; allows for Reverb to trail over into next channel whenever channel is switched. Option available. The Vesperado mod. 547p Try 985p, otherwise anywhere between 470p - 2n2. Remove link Bright Cap or make 120p Leave this stage at Unity for BOTH outboard gear AND IC3! Channel benefits from a bleed in the pre-emph. Option available for Global SPL bleed: 97p - 99p OK. additional bleed ~10 - 15p. pre-volume, but I no Switchable Reverb opamp (Lead IC2), a two-channel summing mixer with a switch, longer do this as it option available. is not wired to provide summing but a simple pass-through, adversely effects tone. Preferred over nevertheless it provides for "trailing" or "decay bleed-over" from either pre-volume bleed channel due to the way it is implemented. "Main TR3" works counter to for optimal tone. this feature, interestingly, yet I removed it. IC2/3: remove, Option: R33 may be 33k adjusted to help socket, and install bring Dry signal up NJM2121D. to unity gain, ganged along with Parallel FX the Wet, so that CL OD when the FX Loop is Reverb engaged (especially when the FX MIX is past "1") the signal maintains a nominal level. "Rear R39/41" can remain at stock value for this option. Remove treble Increases bleed cap Remove for faster current to switching between photocouplers CL/OD, but will produce audible "pop". Option available. C39 on some PCBs Deep Boost: Tant. 16dB > 8dB IC4: Try TL072ACP, or some other IC for better slew rate. C28/31-3: 3u3 tant. The Vesperado mod. Printed: 19 Oct 2007 13:50 j:\tsl_dsl_redesign\jcm2-60\tl10_60_02_iss20.dgm R13/18 pair: stock values limit headroom. C17/18 re-adjusted for C9 removal, etc. JCM2000 DSL spec: 4n7 Unnecessary as Photocoupler has been replaced with a relay. 1u pol. for Crunch *** tightness, 33u pol. for emulating a deep Full Treble Peaker III Stack response... bleed here CL inject point kills pick Makes Clean Reverb Mix trim 22n removes boom. attack. channel pedal Remove. *** Relocate friendly. CL Inject Removes awful clipping scheme. Peaker II 1959 spec: 1k, good Improved filtering. R14/15/17/34: 1k5 for classic and clarity. 2203 spec: modern tones 820R, compressed. **replace all 1W resistors with 2W types *** Suggest lifting backside leg of R80 and Remove to allow redirecting it to backside of R29, before Pin Reverb to "trail" 2 of V2A, so as to prevent interference with across channels modification of that stage's cathode when switching. bypass, where signal is in negative lobe. Option available. Four stages is ample for the CL channel. * raise off board Furthermore, Peaker III will not interfere for adequate air with it but will only effect OD1/2. circulation Replace with a 3H or 10H Replace large caps throughout with low-ESR types. Choke FRED 2.7Vf 40ns 30A 1200V, or better (x8) Bias range improved for cooler operation. Tant. or Nichicon FG, etc. Prolongs longevity. The Vesperado mod. For a channel Treble Bleed solder a small cap between Link 1 & 2, leaving the links intact. I do not use one These two components degrade signal for this channel. bandwidth and dynamics, remove them and your pickups and pedals will thank you! The Vesperado mod. C4 may be fitted with anything between 470p - 2n2, yet 470p is preferable here. NB: "VR2//Treble Bleed Cap" Solder this cap between Link2 and VR2 pot frame. Suggest NB: A B50k can be fitted with a 50k Pre-volume Global Bleed across Lead R21 resistor across it to achieve the Treble Bleed instead, for placing a bleed proper range, however the taper option available. here adversely efffects tone. becomes logarithmic. This alters the behavior of what otherwise would be a B25k. remove NB: VR3 *must* be made 250k for that Marshall tone as it interacts with the slope resistor; the 200k may well provide for a more "useable sweep", but the tone suffers for it. B22K is B20k on PCB. The Vesperado mod.
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