Popular Mods

Service Type Price Guide Description
Speaker Swap
£30 Speaker upgrades or replacement of faulty driver.
Cap Job
Replacement of the electrolytic capacitors that are prone to drying up and degradation over time. Worthwhile on amp after about 10 years use or as an upgrade on modern Fenders that use “budget IC” grade parts swapping out for high end F&T low ESR caps. Includes the large power supply reservoir smoothing capacitor as well as the pre amp de-coupling capacitors, bias and cathode bypass caps. Price varies by amp size.
Jack Socket Pro Upgrade
£22 twin jacks, £14 single Replacement of flimsy plastic connectors with professional quality nickel switchcraft or sturdy Cliff jacks. Partiularly worthwhile on the modern Fender HotRod, Blues Deluxe/Deville, Junior etc.
Combo Speaker Lead 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.
Repair £80-125 As per Service and additionally includes some fault diagnosis and repair. Good for Noisy amps (hums, rustles, cracks), Unreliable amps – cutting out, volume dips
Notes: Many mods require the amp to be serviced at the same time. Modding a faulty amp is not a good plan.


Fender Mods

Fender Hot Rod Deluxe / Deville and Blues Deluxe / Deville

Fender Cool Runnings 230v to 240v Conversion suitable for most Fender Amps made for the EU market, since 1990s, e.g. Hot Rods, Blues Deluxe, Deville, Blues Junior, Supersonic etc. Most Fender amps sold in the UK were manufactured for the EU market and have been set to run at 230v (there is usually a small oval 230v sticker on the rear of the amp. However, since most people in the UK actually receive 240v from their supplier. The problem with is is that your amp will be running a little hotter than it should. This mod will ensure maximum valve life and reduced heat damage to the amp’s PCB. Included within service £15

Lead Dress noise reduction improvements included within service

Chassis Droppers Dropper resistors feature in most amps and they are there to provide a low voltage power supply typically of +/-15v to power effects loops, reverb driver chips and channel switching type functions. The problem is that they get very hot (80 degrees c++) and the heat damage causes the PCB tracks to become fragile and strange behaviour to occur e.g. unreliable or slow channel switching, strange noises on the reverb or effects loop. This mod removes the dropper resistors from the PCB and the heat and transfers them with upgraded chassis mount resistors wired in with point to point wiring so that all heat is transferred away from the amp via the metal chassis. The amp works as normal and continues to be easily serviceable ofr other issuess.

Fender Blues Junior

Cool Runnings
Sets the amp for the nearest voltage to operating conditions e.g. 240v in the UK, 230v in Europe etc. Most Fender amps since 1995 have been made for Europe 230v and this causes them to run at around.
Included within service.
Bias Correction Circuit mod to reduce the power valve’s bias current by around 10-15% and ensures maximum valve life. included within services.
Lead Dressing Helps minimise noise on the amp. Included within service.
Adjustable Bias Suitable for all Fender Blues Jr versions. 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. £22
Billm style basic mods Includes power supply stiffening, twin style tone stack using Orange Drop caps, adjustable bias mod anti oscillation mod. £80
Presence Control Adds a presence control to your Fender blues junior right above the fat button. £22
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. £25

Marshall Mods

Marshall JTM 30

Chassis ventilation mod. Adds a small gap of 7mm at the rear of chassis to allow heat to escape but prevent small fingers entering.

JTM have the DI socket arranged such that once you plug in you can’t remove your XLR unless you happen to have a screwdriver or penknife to hand as the locking mechanism is right next to the cabinet. This mod reverses the DI socket and adjusts the wiring accordingly.

Marshall JTM 60

As per JTM 30 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.


Cool running bridge rectifier mod reduced bias current mod.

Vox Mods

AC30 TB / TBX – Mag7 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.

Roland Mods

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.

Harp Amp Conversions

Alnico Magnet Harp Conversions – Tried and tested on VHT, Harley Bentons and Epiphone amps. These kits alter the voicing of the amp to give you the honk you are looking for. Cost approx £40 for the kit, depending on model and £150 for fitting.

Other Mods

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…