Fender Amp Modifications

We can help you own your tone with customizations that add new features to your amp or fine-tune its performance.

Most Silverface Models

• Convert to a better bias adjustment circuit for improved tone and longer power tube life for your silverface Fender amp? This is included in the "blackfacing" conversion or can be done to many other amps as a separate mod. 

• Remove the "ticking" sound in your vintage Fender vibrato circuit.
Price: $15 (minimum labor rates apply)

• Convert circuit to Blackface specification (see below). Blackfacing: This term refers to the conversion of Fender Silverface (SF) amps (which were built from around 1968 to around 1980) to the more desirable Blackface (BF) circuit configuration (circa 1964 to 1967). Most SF Fenders can be converted to BF spec. for a much lower cost than purchasing a vintage BF model. There are some exceptions, mainly the "ultra-linear" amps which are the 70 watt and 135 watt versions of some models (from the late 70's).  Cost ranges from around $50 to about $100 depending on the model and year (minimum labor rates apply).


Blackface amps were made with a black faceplate and featured the pre CBS circuit design used by Fender before the advent of the silver faceplates. It featured a better bias circuit that allowed for more precise bias settings for your output tubes. Blackface models also had some different value components in various places throughout the amp which resulted in what most players consider to be a better tone. The number of changes varies according to amp model and year. When we blackface your amp, we change these components, re-bias the amp, and on some amps we make changes to the wiring. Selected wires are re-routed and/or shielded or small capacitors are added to stabilize the amp so that it will not become unstable after changing the components. These wiring changes are often necessary because some SF amps become somewhat unstable after converting to blackface spec. This is because CBS made changes to the SF wiring to lower manufacturing costs. These changes sometimes caused instability in the amp, which required them to make other circuit changes to offset the new wiring problems. These circuit changes fixed the instability but adversely affected the tone of the amp. This is one of the reasons why blackfacing can improve the sound of your amp.

What to expect:

That really depends on the amp being converted. The amps that can benefit the most from this mod are the late '68 through late '69 versions of certain models. These are the amps that gave silverface Fenders a bad name when there were introduced. Blackfacing these amps results in a more classic Fender tone with better dynamics, more controllable overdrive, extended frequency response, slightly less flabby bass, and clean tones that have a more open and sparkly sound. In addition, the bias circuit will be converted to a standard blackface type that allows for precise adjustment without pulling the amp chassis. This saves time and money on future output tube replacements. For most Silverface amps not built in the above time period, you still get the bias adjustment mod but the other changes will be a bit subtler. Basically, the tone will get a bit more harmonic, very slightly more distorted in a good way and bass will be reduced slightly. However, some players may prefer the tone of an unmodified '70s Silverface amp which generally has a really great tone if working properly.

Pricing for this service varies but is generally about $50 - $100 for most late 60s and early 70s Silverface Fender amps. Master volume and high power models such as Twins and Showmans can be a little higher depending on how you want us to deal with master volume controls and pull/boost controls. Ultra-linear amps can be considerably more and still won't really sound like blackface amps because of the different transformers in these amps. Some amps such as Princeton, Princeton Reverb, Champ and Vibro Champ have the same circuit design on Blackface and Silverface models. There are still differences in tone for a couple of reasons. The pots, (controls) had a different taper on later Silvervace models. This caused some of the controls to respond differently than the older versions. The same tones are there but at different settings of the controls. Controls with the original tapers are no longer available but we can get closer than what came on the later Silverface models. Pot replacement is about $18 each (minimum labor rates apply). There were also speaker differences on some models and years. Different speakers and power transformers can account for more tonal differences. There were also different rectifier tubes in some models and changes to the cabinet construction.

Be sure to check out the "Mods for Most Amps" section for even more options.

All Blackface Models

• Install a grounded AC cord and correct the out of date AC wiring so that the amp will be safer and much less likely to cause nasty electrical shocks.
Price: $25 (minimum labor rates apply)

Be sure to check out the "Mods for Most Amps" section for even more options.

Most Models without Reverb

• We can add spring reverb to your Fender Deluxe, Bandmaster, Concert or Showman. You'll have to give up the vibrato function and the "Normal" channel that you probably never use anyway. The new reverb circuit will feature dwell, bass and treble controls.
Price: about $245 to $295 depending on whether you want it to be foot-switchable or not.

Note: there is not enough room in the head cabinets to add the tank without excess humming so if you want this added to a head model you'll have to find a bigger cabinet or mount the tank outboard of the head cabinet. There is no problem adding the tank in combo models. Not available for Champs, Broncos and Princetons.

Be sure to check out the "Mods for Most Amps" section for even more options.

Most Models with Reverb and Tremelo

• Wire for reverb and tremolo on both channels
Price: $30 (minimum labor rates apply)

Be sure to check out the "Mods for Most Amps" section for even more options.

Princeton Reverb (Blackface and Silverface)

• Increase intensity of tremolo effect.
Price: $15 (minimum labor rates apply)

Be sure to check out the "Mods for Most Amps" section for even more options.

Blues Jr.

• Correct the bias circuit so that the output tubes no longer overheat. Overheating tubes can cause damage to the tube sockets, circuit board and premature failure of the tubes. A good time to have this done is when output tubes are replaced.
Price: $25 (minimum labor rates apply) for fixed resistor. An adjustable resistor can be installed as part of the BillM mod (see below) or individually for about $80.

• Correct the factory design problem with wiring that causes ultrasonic oscillation, bad tone and premature tube failure. (This is not a problem on every Blues Jr. We can scope the output to see if your amp is in need of this mod.) Included in the BillM basic mod.
Price: $20 (minimum labor rates apply)

• Replace both plastic output tube sockets with more durable ceramic type.
Price: $50 (minimum labor rates apply)

• Install a 2-position power switch so you can have a standby function without modification to the chassis or board.
Price: $30 (minimum labor rates apply)

• Improve control taper
On the green board versions (older production), Fender installed a linear taper bass pot and an audio taper treble pot. This caused the bass control to be too touchy in the low numbers and the treble control to not do much until it reached the high numbers. We can update both pots to cream board (later production) specs. A good time to do this is during the BillM mod (below)

Price: $25 if the board is removed for other service (minimum labor rates apply)

• Install the Bill M mods.
Either you can purchase the kits from www.Billmaudio.com or we can supply the parts for the "Basic Mod" and several others from our inventory. Please note that the bias and oscillation mods above are included in he BillM basic mods. Some mods such as the "clean boost module" and transformer upgrades must be purchased from Bill.
Price including parts:
Cream board amps - $110
Green board amps - $130

Be sure to check out the "Mods for Most Amps" section for even more options.

Blues Deluxe, Blues DeVille, Hot Rod Deluxe and Hot Rod Deville

We've developed our own modifications for the Hot Rod amps that will improve the tone and controllability of the amp. Here is what you can expect...

1) The clean channel will have a somewhat more classic-type tone with a little less gain. The bass will be slightly reduced and bass frequencies will be a bit tighter overall. The clean channel volume control will not be so touchy in the low numbers so you'll have a bit more adjustability at lower volume.
2) When playing the overdrive channel, the Master Volume control will be more evenly adjustable instead of being so touchy in the low numbers.
3) The shrill treble tone of the overdrive channel will be slightly reduced for a smoother sound.
4) Ghost notes that are normally heard when playing single-note leads at high volume will be greatly reduced and the low strings will sound a bit tighter (less flabby).

Hot Rod Deluxe $135
Hot Rod Deville $145

*** NOTE - a substantial portion of the price of these mods is the disassembly of the amp, removal and re-installation of the main PC board. If your board is being removed for other work, the price of these mods will be lowered by about $65.

Be sure to check out the "Mods for Most Amps" section for even more options.

• Triode/Pentode Switch (1/2 power switch)
This allows you to reduce your output power level to about 1/2 of normal. This usually means a reduction of around 20% in output volume. There is also a slight reduction in treble.
Price: $85

Be sure to check out the "Mods for Most Amps" section for even more options.

• Install metal Switchcraft input jacks. These are much more rugged than the plastic ones installed in the American-made Deluxes and Devilles.
Price is $95.
***If we already have the board out for other repairs or mods, we can upgrade the jacks for $35. The Mexican versions (Reissues) of these amps have upgraded plastic jacks that don't typically break.

• These amps have have large power resistors mounted on the PC board that tend to overhead and cause damage to the solder connections and copper traces on the back of the board. This is a very common problem on these amps and causes problems with channel switching and other issues. We can remove these resistors and replace them with super high quality chassis-mounted resistors. This will remove the head from the board and eliminate the possibility of ever having problems in this area.
Price: About $60 if we have the board removed for other work. Cost will be higher the board is removed just for this work.

• There are also several Fender factory reliability mods for the early versions of these amps (especially Blues Deluxe). We'll have to look at your amp to see if these have already been done.

• The 4 X 10 version of the Deville had under-rated speakers from the factory and we've seen many bad ones. For a vintage style tone at a good price, consider having us install a set of WGS G10C or G10C/S speakers. For a deeper, warmer, and louder tone, try the Eminence Ragin Cajun speakers. For a similar effect but with a bit more midrange, try the Eminence Ramrod. They're all rated at 75 watts each and carry at least a 5-year warranty so you won't have to worry about trashing them no matter how loud you play. Other 10" speakers are also available. Mixing two or more speaker models is another option.

Be sure to check out the "Mods for Most Amps" section for even more options.

Deluxe Reverb

• Remove the treble boosting capacitor on the reverb channel for a warmer tone. This is a popular mod on the re-issues but rarely needed on the vintage ones.
Price: $10 (minimum labor rates apply)

• Install a solid-state rectifier and 6L6 output tubes. This will give you a bit more clean headroom and volume. We have to make sure your power supply capacitors are in good shape before doing this mod. In fact, I recommend adding/changing some of the filter caps to higher values for this mod.
Price: varies depending on the tubes you choose.

• Speaker Upgrade.
There are many options but my current favorite is the G12C/S from Warehouse Guitar Speakers (WGS). If you prefer lower headroom, the WGS Liberator is a great choice.

Be sure to check out the "Mods for Most Amps" section for even more options.

Custom Vibrolux Reverb

• Negative Feedback Loop
These amps don't have a negative feedback circuit. That means they have excessive background hiss and limited clean headroom.
Price: about $80

Be sure to check out the "Mods for Most Amps" section for even more options.