Amplifier Mods
Looking for a tone you just can't seem to get from your amp? Perhaps you really like the tone of a particular high-end amp but just cannot afford it yet?
Despite what many people might believe, most tube-based amplifiers are quite similar in design, differing in the number of gain stages, how the stages are setup and driven, how the tone-stacks are setup, and the type of output tubes. Yes, a few amplifiers use various tricks and configurations, but nothing terribly unusual. It's a good chance the amp you have, if at all similar to an amp you'd like emulate, can be mod'ed to a state where it better meets your needs.
At Williams Vintage Amplification, Amplifier Mods are not a problem. I will mod your amp whether New or Vintage, though if it involves drilling of holes or other permanent alterations of the Amplifier that might affect the perceived nostalgia value then we will discuss alternatives and options. You are the ultimate one to decide.
Generally the Mods can be grouped into several catagories, the most common of which are presented in the Navigation Links above. Hover on the links to see descriptive terms one might use when referring to these catagories of mods. Explore these sections for more information.
For a list of Common Mods on Common Amplifiers explore the appropriate amplifier links accessed via the Amplifier Specific link above.
I specialize in the extremes of Tone and Gain, and everything in between.
> I have always really appreciated and loved the warm Clean Tones of Classic Fender style amplifiers, with their crisp presence and solid low-end. Many ordinary Amps can be made to have that same wonderful tight and clean tone of a Classic Fender, and any Modern Fender can be returned to that classic tone.
> BUT I also have to admit that there just is no substitute for an ultra-high-gain Amp that can make your guitar almost talk to you, in the realm of the Bogner, Framus, VHT and similar styles. I can turn many normal amps into ultra-high-gain monsters that make the EVH5150 and most Mesas cry in humility. If you think a 5150 or Mesa-Stiletto is a high-gain Amp, you haven't heard an Ultra-High-Gain Amp.
Keep Checking Back as I continue to update information as the mods database grows, and as time permits to evolve this site.
From the Clean of a Twin to the Smooth Overdriven Distortion of an Ultra-High-Gain Amp, Preamplifier Gain Stages and the Power Amplifier Response make a huge difference.
So What can be done with your Amp?
Most musical instrument Amplifiers have preamp configurations somewhere in between the extremes of the old Fender clean designs and the more modern ultra-high-gain styles like Bogner, Framus, or VHT.
Whether your amp has not enough gain and you want some crunch or overdrive, or too much gain for you and you want Clean, It can almost always be done! I especially love the challenge of the ultra-high-gain mods and conversions.
Some steps associated with manipulating the design to increase an Amps gain and character:
• Remove gain dumping attenuation selectively, while maintaining proper balance of the grid-overload conditions within the preamp, and/or rebias a gain stage or two to shift them toward asymmetrical drive.
• Add more gain stages. — Williams Vintage Amplification offers universal preamp boards that are drop-in ready to add 2-stages of gain to your amp with an additional pre-amp tube (12AX7 et.al.). If your amp doesn't have the gain stages we need, we can add 'em.
• Modify the frequency shaping to massage the gian into the proper regions for your desired tone.
Of course, perhaps your amp already has a bit too much crunch or distortion or you want to open up the headroom a bit or clean up the tone some. This is an entirely different process, though often the same tricks used by the amp-makers can be used here too. All too often the cause of a bit less clean amp than desired lies in the Power Amplifier section. — No problem. This too can be addressed. The following are some steps we might follow:
• Add attenuation stages at the appropriate overloading stage(s), and/or rebias the gain stage(s) for more headroom. Possibly, bypass gain stages if necessary or large changes are desired.
• Address Power Amplifier distortion with selective modification of the Negative-Feedback circuitry (or add feedback if not present), change the output transformer, or perhaps even change the power tube type. EL84s are notoriously dirty/gritty sounding tubes, for example, and moving to 6V6s can completely change the amp's character.
Check out the Tech sections for more information regarding the technical details of these techniques.
What's Tone got to do with it? — More than you might think!
Every musician knows the importance of the tone controls on their amplifier, but few understand how these controls interact with the gain stages to give each amp its unique tonal quality. The good thing is there's quite a bit that can be done with adjustments to the tone control circuitry to help change an amps sound.
Generally, one can consider the following tone control mods useful for consideration:
• Mod the depth of the mid-scoop in a conventional tone-stack. — Or, mod the tone-stack mid contour to enhance the range of the mid-control. There are several configurations of tone-stacks that are possible.
• Add a Single-Knob Tone Control function. Full Tone-Stack additions are covered in the Architectural section.
• Add Mid-Boost for a thick midrange resonance for crisp lead work, or a Bright-Boost for increased high-end tone.
• Add Presence control for sparkling top-end clarity.
• Add feedback based Bass-tightening around the power-amp for tightened low-end.
• An Output Transformer Upgrade for improved response and tone is probably one of the most important considerations for most modern Amps. Almost universally, in production grade Amps, the transformers are barely up to the job. This includes many of the Modern Fenders even - They just don't live up to the Classics. If you want tighter and deeper low end and an overall fullness your amp just doesn't seem to have an Output Transformer Upgrade may be for you.
Many combinations of these tone control based mods are possible in most amps to move the frequency response around to where you like it and remove artifacts like a flat-toned boxey sound characteristic of many inexpensive amps.
Email me with your thoughts on how your amp sounds and how you want it to sound and we'll work out the details of what's possible for your amp.
Need a simple Effects Loop, or perhaps just another Speaker Output Jack? Most Amps these days fall into either the ultra-featured or the under-featured catagory.
If yours is under-featured I'm sure there's a way to add the feature(s) you're looking for.
Below is a list of the most commonly requested simple features for addition to amplifiers. If you don't see what you're looking for on the list, just email me and let me know what you're looking for!
• Add a simple Effects Loop — Unbuffered medium impedance (~50-100K) drive for looping through standard instrument stompboxes and such. (This includes simple unbuffered monitor outputs or Line-Out Jacks.)
• Additional Input or Speaker Output Jacks.
• Add a Standby Switch. (or upgrade the Power switch to OFF-STBY-ON functionality)
Architectural Mods are those more elaborate mods that involve considerable rewiring of existing circuitry or addition of a considerable amount of new circuitry. Have no fear, for these too can be done to enhance your amp in ways you might not have imagined.
A list of typical architectural mods includes:
• A Buffered Effects Loop — Low Output impedance drive for mid-level signals through studio equipment or more sophisticated effects. Buffering can be tube-based or transistor based without changing the tone.
• Addition of gain-stages for overdrive character mods. From just a bit more Crunch, to absolute Ultra-High-Gain insanity.
• Addition of multi-knob tone-stacks where none is present in the amp. This can include Presence controls and Mid-Boost functions or controls.
• Addition of a Reverb Loop and Tank to an amp that has no reverb.
• Addition of an extra Channel to an Amp, or emulation of channel switching with gain or tone function switching.
• Incorporation of the PowerDrive™ power-scaling circuit for maintaining tone from Full-Power down to ~100mW. Now this is an underutilized function for those wanting full Tube Amp flexibility. An awesome Amp flexibility upgrade.
If you don't see what you're looking for, email me! Almost anything is possible.
Vintage Fender Mods
Vintage Fender Amplifiers with the Normal/Vibrato Channel configurations are some of the most traditional and fantastic Tube Amplifiers out there. Even so, these amplifiers too can have quirks and nuances that are subject to improvement.
Fender Blues Jr.
The Blues Jr. is a Very flexible amp with proper treatment. Stock the tone rage is very compressed and flat, the bass end is light, the character is gritty, and the amp has a generally midrangey "boxey" small sounding tonal quality. With mod'ing the amp can be improved, or totally enhanced, and with a full makeover it can be made to have the tone and character of a Fender Deluxe (one of my favorite Amps). On the other end of the spectrum, the Blues Jr. has all of the right circuitry to get quite a mean level of overdrive, and the flexibility of having a fully tube-buffered effects loop without excessive cost.
Epiphone Valve Jr.
The Valve Jr. is a very nice simple design ripe for mod'ing. The base design suffers from various imperfections arising out of the low-cost trade-offs made by Epiphone. The Valve Jr. does however, offer a considerable range of tones and characters from a near Clean to a nice Bluesy Overdrive with appropriate modification. Being a Single-Ended Amp, the Valve Jr. is not fully capable of a totally clean tone at full power levels, but the base design isn't capable of clean at almost Any power level, so there's a lot of room for improvement. Explore the page on the Valve Jr. for more information and pricing for many standard mods.