General Feature Mods
| Mod | Description | Price |
|---|---|---|
| Tube FX loop | Adds a Tube based serial FX loop to your amp. Requires adequate power for the additional valve. Based on the popular Merlin Blencowe aka Valve Wizard Kit. | £236 |
| Master Volume | Adds a PPIMV to your amp. Control can go on the rear or front panel according to available space / preference | £85 |
| Speaker Swap | Speaker upgrades or replacement of faulty driver. See HotRox and Lean Audio for speaker suggestions | £45 plus speaker |
| Combo Speaker Cable Extension Upgrade | Upgrade the flimsy speaker lead on your combo with a low loss Van Damme OFC cable and Neutrik / Switchcraft heavy duty jack plug. Add extra length to share the cab with alternate amp head. | £27 for 1 metre |
| Adjustable Bias Mod | This mod adds a bias trimmer pot inside the amp for adjustment by a qualified engineer. Great for older amps had no provision for adjusting the bias like Sound City etc | £91 |
| Fan Temperature Controller | Adds a temperature sensor to reduce fan noise at low volume levels great for home playing and recording mostly for Bass amps | £127 |
| Amp Head LED – Fixed Colour | For amps with see through grille like Peavey 5150, Peavey 6505, JSX, Engl. Custom fit aligned to valves – single colour LED highlighting the tubes. Screw installed baton with custom placed coloured LEDs to highlight valves and create shadows. Comes with adaptor and can be disconnected as required. In some amps it can be powered from the amp directly too but this requires evaluation of the power capability of the amp. | £107 |
| Amp Head LED – Variable Colour | For amps with see through grille like Peavey 5150, Peavey 6505, JSX, Engl. Coloured LED strip baton mounted either up or down lighting, or shining from a corner at 45 degrees. LED strip comes with a controller to have any colour you like and comes with some effects like sequences (static is nice but the sequences are a bit annoying). Also a range of diffusers for makiing looks like a solid ray of lighting colour. | £120 |
| Amp Head LED – Variable Colour, Sound to Light | For amps with see through grille like Peavey 5150, Peavey 6505, JSX, Engl. As above but with sound to light controller for extra effects | £136 |
| Cabinet Grille Cloth Replacement | Replace speaker grille cloth due to ageing or to achieve custom finish. Price based on Marshall black fret cloth at £15 / metre for 1 metre. | £115 |
| Speaker Cabinet wheels | Save your back with a set of four pop in / pop out castors. | £115 |
| Cap Job | Replacement of the electrolytic capacitors that are prone to drying up and degradation over time. I always use high end F&T, low ESR caps. Worthwhile on amp after about 20 years use or as an upgrade on some amps. Includes the large power supply reservoir smoothing capacitor, pre amp de-coupling capacitors, bias and cathode bypass caps. Price varies by amp size and the exact capacitors installed.
| £50-100 depending on model |
Fender
Fender Hot Rod
| Mod | Description | Price |
|---|---|---|
| Mains Voltage Correction | Adjust your amp to the correct voltage according to your location. Essential for most Fender Amps made for the EU market to ensure long life. | £12 included in service |
| Lead Dress optimisation | Most Fender Amps are noisier than they need to be. By re-dressing the leads from the transformer it is possible to reduce the amp’s hum. | £12 included in service |
| Chassis Dropper Fix | Dropper resistors appear is many amp circuits and their job is to provide a low voltage power supply typically of 15v for the effects loop, reverb driver chips and channel switching. The problem is that they do get very hot (80 ° deg C) which tends to damage the PCB on Fenders after about 5-10 years. When this happens, you will experience strange fault symptoms like inconsistent channel switching, loss of reverb and squealing noises. This mod replaces the dropper resistors with upgraded aluminium-clad chassis-mounted components point to point wired away from the PCB. Once the mod is applied the lifetime of the amp is no longer limited by this design weak spot permanently. | £72 inc parts |
| Pro Switchcraft Input Jack upgrade | Replacement of Fenders flimsy plastic connectors with professional Switchcraft jacks as per all vintage amps. More info… | £18 per jack |
| Cap Job (Deluxe) | Replacement of the electrolytic capacitors that are prone to drying up and degradation over time. I always use high end F&T, low ESR caps. Worthwhile on amp after about 20 years use or as an upgrade on some amps. Includes the large power supply reservoir smoothing capacitor, pre amp de-coupling capacitors, bias and cathode bypass caps. Price varies by amp size and the exact capacitors installed.
| £64 approx |
| Cap Job (DeVille) | as per Deluxe | £64 approx |
| Master Volume Control | The Fender Hot Rod is just way too loud. The volume control is hard to control at lower levels. Fender addressed this a little bit in the Hot Rod III by using slightly different taper pots but it is not a significant improvement. One solution is to add a removable master volume in the effect loop, called the Lion Tamer. This plug-in module works well but it is a flimsy solution and more importantly you lose the access to the effects loop. Instead fitting a permanent MV control you retain access to the effects loop and gain complete control of the amp. The control is added to the front paned just above the effects loop and massively improves the versatility of these popular amps. See the video clip here for a demo. Hot Rod master Volume demo video here | £58 |
| Negative Feedback Control | The Hot Rods have global negative feedback like most amps, but oldder amps like a Tweed do not. This mod gives you control on the amount of negative feed back and adds a control giving to the stock HotRod on mimnimum and full-tilt tweed bark at maximum levels. Great mod combined with the master volume. | £46 |
Fender Blues Junior
| Mod | Description | Price |
|---|---|---|
| Mains Voltage Correction | Ensure long life of your power valves and 5% cooler running of your FBJ by correcting the mains operating voltage setting of your amp. Essential for most Fender Amps made for the EU market (factory set for 230v) but in the in UK should be adjusted for 240v operation. | £15 included for free in service |
| Lead Dress optimisation | Most Fender Amps are noisier than they need to be. By re-dressing the leads from the transformer it is possible to reduce the amp’s hum. | £15 included for free in service |
| Bias Reduction | Circuit mod to reduce the power valve’s bias current by around 10-15% and ensures maximum valve life.Does not apply for Fender Blues Junior IV | £15 included for free in service |
| Fully Adjustable Bias | This mod adds an adjustable internal bias control to the amp. This gives full control over the amps bias and allows you to lower it or push the bias depending upon you preference of tone or appetite for buying new valves. Does not apply for Fender Blues Junior IV | £35 |
| Billm Style Basic Mods | Includes: Full F&T re-cap – including stiffened (reservoir cap) Twin style tone stack using Orange Drop caps, Mid mod Bias reduction mod Anti oscillation mod (earlier models only) Master volume range fix | £106 |
| Presence Control | Adds a presence control to your Fender blues junior right above the fat button. | £32 |
| Sparkle Control | Adds a pull / push pot in between the mid and master volume control which tames some of the brightness especially on the Fender blues Junior III variant. I don’t find the mod that effective but people ask for it form time to time. | £32 |
| Pro Switchcraft Input Jack upgrade | Replace the cheap plastic jack socket with nickel plated Switchcraft jack as per all high end vintage Fender amps. Essential upgrade for amps that are used in gigging environments. | £18 |
| Cap Job | Replacement of the electrolytic capacitors that are prone to drying up and degradation over time. I always use high end F&T, low ESR caps. Worthwhile on amp after about 20 years use or as an upgrade on some amps. Includes the large power supply reservoir smoothing capacitor, pre amp de-coupling capacitors, bias and cathode bypass caps. Price varies by amp size and the exact capacitors installed.
| £52 |
Fender Blues Deluxe / Deville
| Mod | Description | Price |
|---|---|---|
| Mains Voltage Correction | Adjust your amp to the correct voltage according to your location. Essential for most Fender Amps made for the EU market to ensure long life. | £12 included in service |
| Lead Dress optimisation | Most Fender Amps are noisier than they need to be. By re-dressing the leads from the transformer it is possible to reduce the amp’s hum. | £12 included in service |
| Chassis Dropper Fix | Dropper resistors appear is many amp circuits and their job is to provide a low voltage power supply typically of 15v for the effects loop, reverb driver chips and channel switching. The problem is that they do get very hot (80 ° deg C) which tends to damage the PCB on Fenders after about 5-10 years. When this happens, you will experience strange fault symptoms like inconsistent channel switching, loss of reverb and squealing noises. This mod replaces the dropper resistors with upgraded aluminium-clad chassis-mounted components point to point wired away from the PCB. Once the mod is applied the lifetime of the amp is no longer limited by this design weak spot permanently. | £72 inc parts |
| Pro Switchcraft Input Jack upgrade | Replacement of Fenders flimsy plastic connectors with professional Switchcraft jacks as per all vintage amps. More info… | £18 per jack |
| Cap Job (Deluxe) | Replacement of the electrolytic capacitors that are prone to drying up and degradation over time. I always use high end F&T, low ESR caps. Worthwhile on amp after about 20 years use or as an upgrade on some amps. Includes the large power supply reservoir smoothing capacitor, pre amp de-coupling capacitors, bias and cathode bypass caps. Price varies by amp size and the exact capacitors installed.
| £64 approx |
| Cap Job (Deville) | as per Deluxe | £64 approx |
| Master Volume Control | The Fender Hot Rod is just way too loud. The volume control is hard to control at lower levels. Fender addressed this a little bit in the Hot Rod III by using slightly different taper pots but it is not a significant improvement. One solution is to add a removable master volume in the effect loop, called the Lion Tamer. This plug-in module works well but it is a flimsy solution and more importantly you lose the access to the effects loop. Instead fitting a permanent MV control you retain access to the effects loop and gain complete control of the amp. The control is added to the front paned just above the effects loop and massively improves the versatility of these popular amps. See the video clip here for a demo. Hot Rod master Volume demo video here | £58 |
Fender Deluxe Reverb
| Mod | Description | Price |
|---|---|---|
| Reverb and Tremolo on Both channels Mod | Changes the amp so that Reverb and Tremolo are on both channels on amps based around the AB763 circuit RobRobinette models in this range also include Fender Vibroverb/Vibrolux, Fender Tremolux, Fender Bandmaster, Fender Showman | £79 |
| Fender Deluxe Reverb 68 Custom Noise Reduction Mods | As per the videos of PsionicAudtio on youtube to reduce the amp’s hiss and background noise by 50%, Correct the channel bridging of reverb and tremolo. Point to point volume pot bypassing PCB for vintage channel. Plate resistor upgrade. Custom 68 Noise Reduction Video | £91 |
| Fender Deluxe Reverb 68 Custom NFB control | Adds a toggle, or rotary switch to change the NFB as per either the 65 or 68 Deluxe Reverb. This is a further noise reduction mod. NFB control demo | £45 |
| Middle Control, on either or both channels | Adds a pot to the rear of the amp and widens the tone range of Fender’s much loved Deluxe Reverb to cover the range between stock, Twin and Tweed tonestack. Middle Control demo | £56 |
| Cap Job | Replacing all the electrolytic capacitors in the power supply with high end F+T parts. Helps restore bass response on old amps and improve reliability in newer amps. | £56 |
Fender Twin
| Mod | Description | Price |
|---|---|---|
| Reverb and Tremolo on Both channels Mod | Changes the amp so that Reverb and Tremolo are on both channels on amps based around the AB763 circuit RobRobinette models in this range also include Fender Vibroverb/Vibrolux, Fender Tremolux, Fender Bandmaster, Fender Showman | £79 |
| Mains Voltage Correction | Adjust your amp to the correct voltage according to your location. Essential for most Fender Amps made for the EU market to ensure long life. | £12 included in service |
| Lead Dress optimisation | Most Fender Amps are noisier than they need to be. By re-dressing the leads from the transformer it is possible to reduce the amp’s hum. | £12 included in service |
| Chassis Dropper Fix | Dropper resistors appear is many amp circuits and their job is to provide a low voltage power supply typically of 15v for the effects loop, reverb driver chips and channel switching. The problem is that they do get very hot (80 ° deg C) which tends to damage the PCB on Fenders after about 5-10 years. When this happens, you will experience strange fault symptoms like inconsistent channel switching, loss of reverb and squealing noises. This mod replaces the dropper resistors with upgraded aluminium-clad chassis-mounted components point to point wired away from the PCB. Once the mod is applied the lifetime of the amp is no longer limited by this design weak spot permanently. | £72 inc parts |
Fender Princeton 112+
| Mod | Description | Price |
|---|---|---|
| Princeton 112 Clean Volume Abruptness Mod and Drive Channel Fizz Taming Mod | See Princeton Mod Post for details | £30 |
| Princeton 112 Master Volume Pot Mod | See Princeton Mod Post for details | £30 |
Fender Supersonic
| Mod | Description | Price |
|---|---|---|
| Mains Voltage Correction | Adjust your amp to the correct voltage according to your location. Essential for most Fender Amps made for the EU market to ensure long life. | £12 included in service |
| Lead Dress optimisation | Most Fender Amps are noisier than they need to be. By re-dressing the leads from the transformer it is possible to reduce the amp’s hum. | £12 included in service |
| Chassis Dropper Fix | Dropper resistors appear is many amp circuits and their job is to provide a low voltage power supply typically of 15v for the effects loop, reverb driver chips and channel switching. The problem is that they do get very hot (80 ° deg C) which tends to damage the PCB on Fenders after about 5-10 years. When this happens, you will experience strange fault symptoms like inconsistent channel switching, loss of reverb and squealing noises. This mod replaces the dropper resistors with upgraded aluminium-clad chassis-mounted components point to point wired away from the PCB. Once the mod is applied the lifetime of the amp is no longer limited by this design weak spot permanently. | £72 inc parts |
Fender Super Reverb
| Mod | Description | Price |
|---|---|---|
| Normal Channel Tone Stack Mod | Normal Channel change tone stack to super reverb for different tone options | £41 |
Fender Bassman
| Mod | Description | Price |
|---|---|---|
| Bassman 50 – Bass channel to guitar voicing mod | Make the bass channel same as guitar channel for extra versatility. | £87 |
| 59 Reissue Bias Pot | Adds a bias pot to tweek the bias for different valves | £29 |
Marshall
| Mod | Description | Price |
|---|---|---|
| JTM30/60 Overheating Mod | Chassis ventilation mod. Adds a small gap of 7mm at the rear of chassis to allow heat to escape but prevent small fingers entering. | £38 |
| JTM30/60 Common Sense DI connector | Changes the DI so that you can use it without getting your connector stuck. | £23 |
| JTM60 Gunnar Tone Mods | The Gunnar mod removes the clipping diodes from the amp’s fizzy drive channel, rebalances the gain to provide a classic valve blues breaker tone. https://soundcloud.com/user-284115725/marshall-jtm60-stock-v-gunnar-mods | £125 |
| DSL401 Overheating | Cool running bridge rectifier mod Reduced bias current mod. Increased Ventillation | £31 |
| Eddie Van Halen 3 x Mods (Fat Cap, Mid Pot and Negative Feedback) for 1959SLP, Plexi and similar | Middle Pot change Adds a mini toggle switch to the rear panel to switch in or out a filter capacitor on V2 cathode. Rolls off slight amount of high frequency – hence fatter sound. Adds a rotary switch to the rear to switch between three levels of Negative Feedback in to the power amp. More NFB gives a more refined HiFi sounding amp and less NFB gives more brashness and bark. Requires chassis alterations. | £86 |
| JCM2000 DSL / TSL Bias Fix | Dr Tube Mod extend the life of this range of amps by removing the bias circuit from the PCB.
| £204 |
Other Brands
Vox
| Mod | Description | Price |
|---|---|---|
| AC30 TB/TBX Mag 7 Mods | Application of 7 magnificent mods described on YouTube by Psionic Audio reduce noise, increase reliability of these wonderful reissue AC30s made by Marshall from around 1993. | £152 |
Roland
| Mod | Description | Price |
|---|---|---|
| Roland JC120 Noise Reduction | Roland Jazz Chorus amps are renowned for their crystal clear tone and also their irritating hiss. By slight restructuring of the pre-amp gain this can be cured and works on JC120, JC77 & JC55. Also has side effect of making the volume control some what more gradual. Overall tone and maximum volume is not impacted. | £122 |
| Roland Street Cube Headphones / Line out switch | Is it possible to modify the Headphone Jack socket on my Street Cube to become a Line Out socket i.e. so that when a cable is plugged into the Headphone jack, you can still hear the signal coming through the main speakers? In addition can a switch be installed to switch back and forth between “Line Out” with speakers sounding and “Headphones” with speakers muted? I have found a youtube video that purports to show how to carry out this modification. https://www.youtube.com/watch?v=kylovLsBwBY Fast Track required” | £55 |
Custom Builds and Conversions
| Amp Coaching Session Type | Description | Price | _dt |
|---|---|---|---|
| Kit Amp coaching session – two hour. | Two hour private one-on-one build or diagnosis valve amp coaching session. Fancy building a kit but uncertain about how difficult it is? Learn the best build sequence, techniques. Learn to use test equipment like an oscilloscope, miultimeter, dim light bulb. Safely let me take care dangerous high voltage power up stage. Typically allow for two to four sessions for a 5E3 style amp, depending upon experience level | £190 | 3 |
| Kit Amp Guided Build end to end. Simple amps upto 10w power e.g. champ | Let me be your guide on your amp build journey. Includes build planning with check points, Skills and tools coaching. Unlimited QnA online consultancy and video calls. Final stages power up and any debugging can optionally be face to face. Pre Reqs: Patience, hand tools, stripping wire | £125 | 2.5 |
| Kit Amp Guided Build end to end. For medium amps upto 50w power | Let me be your guide on your amp build journey. Includes build planning with check points, Skills and tools coaching. Unlimited QnA online consultancy and video calls. Final stages power up and any debugging can optionally be face to face. Pre Reqs: Patience, hand tools, stripping wire | £190 | 2.5 |
| Kit Amp Guided Build end to end. For complex amps greater than 50w or including channel switching | Let me be your guide on your amp build journey. Includes build planning with check points, Skills and tools coaching. Unlimited QnA online consultancy and video calls. Final stages power up and any debugging can optionally be face to face. Pre Reqs: Patience, hand tools, stripping wire | £250 | 3.9 |
| Amp Final Stage Safe Power On | Final stages power up and any debugging can optionally be face to face. | £85 | 2 |
If you have read about other mods and want to know more or whether I have tried please drop me a line. I have just mentioned a few popular ones on this page…
Notes:
- Modification included with all service or repair jobs free of charge unless specifically not required.
- Modifiations to amps invalidate manufacturer’s warranty; so please consider carefullly.
Updated 20/10/2025
12:18.