Lots of sites out there offer do-it-yourself instructions, so what sets our kits apart from everyone else? In a word, detail. We take a step-by-step approach, explaining what you’re doing and the reason behind it at every stage of the process. Part numbers are assigned to every component, full-size layouts are provided to build your own circuit boards where appropriate and a complete bill of materials is given with each kit to keep things super organized and easy to understand.
In all cases, the information given is very specific, showing dimensions, exact part locations, etc., so that no guesswork is involved on your part. Best of all, every step that the instructions give is illustrated with a CAD drawing. The significance of using CAD is that of clarity: each diagram is drawn to scale, so it looks exactly like the amp that you’re working on. A schematic is included with each kit for those who wish to understand the theory, but the instructions are so complete that you can mod or build an amp simply by looking at the pictures, as many people have already found.
If you’ve built things in the past from the kits offered by other companies and have been frustrated by their lack of information and hastily drawn diagrams, rest assured that you’re not alone. Circuitrix kits by comparison, take nothing for granted, providing complete, detailed information in order to make the building experience an enjoyable one. Whether you’re doing a simple tweak to a circuit or a major re-design of your amp, the directions given are always clear-cut and easy to follow.
Aside from the money that you’ll save by modifying your own equipment, it’s a rewarding experience to create your own personal sound. The sense of accomplishment that you’ll feel from doing it all yourself is definitely worth the price of admission.
Each of the kits can be purchased as instructions only, or as a complete kit with instructions and all parts. In most cases, the work that you’ll be doing will consist of adding to or changing the parts on the stock circuit board in the amp, as well as changing the wiring around.
There are a few kits however that require you to install a small circuit board in your amp. They are: “Fender Double Shot”, “JCM Pro” and “Marshall FX”. If you order these as a complete kit, you will be provided with a small piece of perfboard that is cut to the approximate required dimensions. At your discretion, you can build the modified circuit by one of two ways.
The first is by pushing the leads of the components through the holes in the board and soldering them together on the other side. This would be the preferred way for most folks, as the circuits that you’ll build on these boards are very simple.
If you prefer, you can also build the boards by installing eyelets and soldering the components to them, much like Fender did in the old days. This is a cleaner way to build and allows for easier servicing and future modification.
The following kits are total re-builds of the amplifiers that they are designed for and require that you install a completely new set of circuit boards. These boards are designed to be built in point-to-point fashion using eyelets as described previously. They are as follows: “Big Bad Bassman”, “Maximum Marshall”, “Missing Link” “Princeton Elite”, and “Build a Blackface Amp”.
In these cases there are a few more options as well, one of those choices being that you can order a complete kit with circuit boards that are cut to size and drilled out with all eyelets installed. This is by far the easier, faster way to go for those of you who want to get something built as quickly as possible. All you have to do here is solder the components to the board and wire it into the circuit.
Another option is to buy the kit with a piece of FR-4 that is cut to a size that’s large enough to accommodate the circuit boards that you’ll need. Buying it this way means you’ll be able to save a few bucks on the price but you’ll have to cut it to the correct size, drill all of the holes using the full-size template provided and install all of the eyelets yourself. This is a lot more work on your end, and also requires that you have the necessary tool to install the eyelets. Cutting the board can be done with a band saw, hacksaw, scoring tool, etc.
Finally, you have the option of buying the completed circuit boards only, without having to buy any of the other parts in the kit. This is for those of you that already own the instructions for a given kit and would like to build another amp from the same plans.
One more thing bears mentioning and that is that if you go to the appropriate page on this site you’ll see a complete listing of all parts that are included with each kit. We stock enough parts to insure that everything listed in the bill of materials will be provided to you should you place an order for a complete kit. In the event that any substitutions are made, they will be done for the sake of upgrading to a higher quality component or one with higher voltage or capacitance ratings.
Many of the components in the kits are also listed on the parts page where they can be purchased individually. Those parts that are not listed on the parts page will not be available for sale on an individual basis. If you don’t buy a complete kit, then it’s up to you to track down the parts that you need that are not listed for sale on this site.
Building and modifying amps is a lot of fun, but there are lots of connections to make and now and then things don't always go as planned. I've been selling these kits for years and when people do get stuck on something, it's usually because of one of three problems: bad solder joints, not following directions, or forgetting to make one or more connections. These kits have been built by many people and they do work if you take your time and pay attention to what you're doing. Since the information is of a very technical nature, you'll probably find as most of us do that you'll have to read some of the instructions a few times before you can get a handle on what's going on. Don't feel bad about it, it's all part of the game. If you do run into something that you're totally stuck on though, please contact me by e-mail and I'll get back to you as soon as I can with an answer. E-mail gives me a chance to take a look at the kit in question and refresh my memory about what was said so that I can give you the best answer possible. My schedule is also pretty full and my time on the phone must be limited to taking orders.
Tube amps contain high voltages that can cause serious personal injury or death. By attempting to perform the modifications contained within this kit, you are assuming all legal responsibility for your personal safety. The instructions contained herein are presented for educational/entertainment purposes only, and you alone are responsible for any possible damage you may cause to yourself or to the equipment that you are working on. Neither the author of this material nor anyone at Circuitrix is responsible for anything that you do with this information, nor is any claim made as to the correctness or suitability of said information. In purchasing this information and/or attempting to use it, you are confirming correct electronic knowledge and experience. If you do not feel qualified to perform the required work, you should consult a qualified technician for assistance. Any mention of Marshall, Fender, or any other amplifier company is in reference to a brand name and/or trademark of that company. No one at Circuitrix is in any way affiliated with any of these companies.
If your tastes lean toward classic rock and blues, then this is the kit you've been waiting for. It responds best to those with an aggressive picking technique and is a complete re-design of the amp. Using a point-to -point technique similar to the old Fender amps, you replace the stock circuit board with one that you build yourself. This totally new design approach lets you finally get those great classic sounds that you've never been able to find with any store bought amp. You get:
· A lead channel that defines the classic rock tone. This distortion sound retains the clarity of individual notes, even at maximum gain settings. It's very touch-sensitive, allowing you to control the amount of breakup with your picking hand. The sound is rich and full and it retains its great character even at low volumes.
· A rhythm channel that is capable of two modes that are selectable via an optional push-pull pot. The first is a conventional clean tone that stays tight and full while giving the player plenty of headroom. The second mode is capable of a wide variety of sounds depending on how you set the gain control. At lower settings, it works great for the blues and really nails the Stevie Ray/Johnny Lang rhythm tone that is so tough to get from most amps. At higher gain settings, this channel also works great for solo work. The greatest thing about it is that you can get all these sounds at any volume. You'll sound great at every gig - no matter how small the club is.
· A great sounding series effects loop that makes pedals and rack-mount gear alike sound better than they ever have. A switch on the panel turns the loop on and off so that you can compare the dry sound to the processed sound to make sure that your tone hasn't changed. Separate send and return level controls let you adjust the loop so that it's compatible with any effect out there.
· Channel switching is done with relays and is very quiet. Set up the two channels the way you want them at the beginning of the night, then step on the button to kick back and forth. Playing a gig has never been easier!
21 pages text, 19 pages diagrams. Instructions only: $37.95. Complete kit w/FR-4 blank: $218.00. Complete kit w/circuit board: $248.00. Circuit board only: $34.95. This kit also works great in Bandmaster and Showman amps.
The Blackface Fender amp is probably the most copied amp design of all time. Buy this kit and you’ll be able to build your own piece of history! As any technician will tell you, the layout of the circuit has a lot to do with the way an amp sounds. Keeping that in mind, the circuit board in this kit has the original parts layout as built in the ‘60’s and the drawings and instructions show you how to wire the amp exactly as they did in the old days. Every single electronic connection is shown in a very easy to follow manner, showing you how to build your very own vintage amp step by step. From the solder joints on the board to the routing of the wires in the chassis, all drawings are done to scale with a CAD program so that each of these diagrams look exactly like the real thing.
Whether you want to build a Twin, Super, Vibrolux or Deluxe, this kit will show you how. Many Blackface amps share the same preamp design and general layout, so you’ll be able to build the amp that best suits your needs simply by altering your choice of transformers and speakers. The dimensions given for the metal work are for a Fender Twin, so you'll have to adjust them somewhat if you are building a different model.
This kit is also invaluable to those of you who are you converting Silverface amps to Blackface specs. There are so many variations between the Silverface amps from the ‘70’s and 80’s that it would be impossible to document a conversion procedure for each one. Buy this kit and the process becomes a simple job of duplicating the wiring shown in the pictures…problem solved!
19 pages text, 20 pages diagrams. Instructions only: $37.95. Complete kit w/FR-4 blank: $218.00. Complete kit w/circuit board: $248.00. Important Note: this kit gives detailed information about wiring, parts location and locating dimensions for all metal work. There is no information about woodwork.
This is a great sounding overdrive mod for Blackface Fender amps with two channels, reverb and tremolo. It’s a distortion circuit that works best for Blues and Alternative players who like the sound of a big Fender being pushed at high volume. Install this mod and you can get that sound without making your ears ring.
· Greatly increased sensitivity and dynamics. Pick hard for more breakup or lighten up your attack to clean things up – total control from your picking hand.
· Get a rich, full sound at reasonable volume levels. Save your tubes and your hearing as well.
· Switch it in and out and still retain the stock sound of the amp.
5 pages text, 6 pages diagrams.
Instructions only: $12.95. Complete kit: $19.95.
Fender blackface and silverface amps have one great sounding channel that everyone plugs into. When the playing situation demands more versatility, many players reach for a stomp box to get a second sound or they go through the trouble of dragging a second amp to the gig. Wouldn't it be great if both channels in your amp sounded equally as good? Wouldn't is also be great to be able to switch back and forth between the two with a footswitch? Buy this kit and you'll be able to do just that. This mod is relatively easy to do and is a must have for any Fender fanatic. You get:
· A relay switching system that changes channels and is totally silent. This is a universal system that can be adapted to pretty much any other amp that you may own as well.
· Reverb and Vibrato on both channels. Use both channels on the amp to maximum capacity and avoid the hassle and expense of having two amps at every gig.
· Both channels can now be totally equal in performance. Retain your stock sound and adjust each channel for a different volume and/or tone and switch back and forth for rhythm and lead. Better yet, buy the "Tweaking Fender Amps" kit and color one channel a little differently than the other. Get maximum flexibility from your old Fender and bring it into the new millennium.
11 pages text, 13 pages diagrams. Instructions only: $17.95. Complete kit: $68.00. This kit is written for two-channel Fender amps from the 60's and 70's that have reverb and tremolo, i.e. Super, Twin, Vibrolux, Deluxe, etc.
If you're using any type of digital effects processor, then you definitely need an effects loop. Rack mounted gear is simply not designed to plug directly into the front of the amp. If this is what you're doing now, then you're losing half of your sound. This mod is designed for a stock black or silverface Fender amp (Super, Twin, Vibrolux, etc.), and is installed where the normal channel is now. This is not to be confused with the simple preamp out/power amp in setup that some people think is a loop. This is a complete circuit unto itself that many techs charge hundreds of dollars for. Build it into your amp and get these features:
Installs easily in your amp - no need to cut the chassis and add a tube. Keeps the amp looking stock for maximum resale value.
6 pages text, 9 pages diagrams. Instructions only: $12.95. Complete kit: $34.95.
This is a real easy kit to build for all you guys that own Fender amps. It applies specifically to all Fender two-channel amps with reverb and vibrato that were built during the 60's and 70's. Specifically, the Deluxe Reverb, Bandmaster Reverb, Vibrolux, Showman, Super, Twin, etc.
Did you know that you're throwing away a lot of your sound? Because of the way that vintage Fender amps are wired, there are circuits that keep the amp from operating at full potential. Your average stock Fender doesn't even start cooking until the volume is at about "7". Works great if you're playing in an amphitheater, but what do you do if you're playing a club gig? More often than not, you turn your volume way down and your sound turns to crap! Not any more. If you love the sound of your Fender amp and you'd simply like a lot more of it, then this kit's for you.
4 pages text, 8 pages diagrams. Instructions only: $12.95. Complete kit: $21.95.
Any preamp sounds much better when it's plugged into a tube power amp. Why buy a separate power amp when you can access the power amp section of your favorite Fender head or combo? These amps are easy to find and reasonably priced and provide that great vintage tone that we all know and love. The switching action of the special jack that you install allows normal operation of the head when you're not using a separate preamp. Have your cake and eat it too.
4 pages text, 7 pages diagrams. Instructions only:$7.95. Complete kit: $14.95.
Wouldn't it be great to have a small amp that's light enough to carry around to small gigs and jam sessions but yet could really crank? Look no further, because here it is. Use this kit to completely re-build your Fender Princeton and turn it into a real powerhouse! Get the features and performance of many larger amps in a small, convenient package. Why carry around that stack when you can dial in the sounds from this dynamite little amp? Best of all, most people think of these amps as practice amps and sell them at bargain prices. Pick one up and turn it into a killer tone machine.
· Two completely separate channels, each with its own tone and volume controls. Channel switching makes both accessible from the floor.
· The clean channel is a nice warm Fender tone with a lot more kick and flexibility than the stock circuit. Keep it at low volume for a sweet and silky sound, or push it at louder levels to get a more bluesy tone. The preamp design of the overdrive channel gives it a Marshall-style edge, while the 6V6 output tubes give it the warmth of a Vox AC-30. Get that singing, violin-like lead tone at levels that won't knock the walls down.
· Reverb is improved for more warmth and clarity and is well balanced on both channels.
15 pages text, 20 pages diagrams. Instructions only: $37.95. Complete kit w/FR-4 blank: $183.00, Complete kit w/circuit board: $213.00. Circuit board only: $34.95.
Whether you're a dealer trying to restore your amp to maximum resale value, or a player on a quest for the best tone you can get, don't pass this one up. All the tricks are here. You'll re-build your amp from the ground up just like all the top techs do. Warm tone, rich harmonics and solid low end that really packs a punch. All this can be yours when you use the information in this kit to restore your amp. These are all closely guarded secrets that have never been available until now.
· How to replace the filter caps in the power supply and restore the punch to your amp.
· Where the crucial coupling caps in the amp are located and what type to replace them with to restore clarity and harmonic richness.
· What components to replace to stop those annoying sporadic noises and make the amp much more dependable.
· How to replace the stock AC cord with a modern three-prong type.
· How to adjust the bias on your amp and stop those expensive trips to the local technician.
· A complete schematic that "talks you through" the amp, telling you what each component does.
· A simple trick to warm up the sound of the amp and balance the tone control section. Find sounds that you never knew were there.
12 pages text, 8 pages diagrams. Instructions only: $12.95. Complete kit:$78.00.
This is the kit you've been waiting for and is a must have if you own a Fender amp. The instructions walk you through the stock circuit step by step and show you how to change key components to tweak the amp just the way you like it. Other companies charge lots more for a lot less information, but for one low price you get all the information in one package. Don't worry if you're not that experienced in electronics - you don't need to be. Everything is explained in complete detail and there are diagrams that guide you every step of the way. All the good stuff is in this one, including:
· How to boost the gain and change the tone.
· Add a midrange pot/ boost the midrange.
· Power supply mods including converting to a diode rectifier.
· Modifying the Reverb and converting to EL 34's.
· Add a power amp gain control, install a contour control for the tone circuit, build your own Tremolo pedal and more.
· Maximize your Fender tone machine and get the sound you’ve always wanted.
15 pages text, 11 pages diagrams. Instructions only: $17.95. Complete kit: $93.00.
Is your JCM 800 channel switcher sounding a little wimpy? These amps were designed a while ago, and just can't keep up to the newer stuff that's out there. Install this kit and give your amp a lot more kick and versatility. This modification is built on the stock circuit board and is relatively easy to install. The clean and lead channels are both re-built, and a completely new channel switching system is installed. The effects loop and reverb are kept stock.
· The clean channel output is kicked way up, making it sound much fuller, with more body and roundness. The harmonics and natural warmth are all here, with expanded tonal capabilities not available from the stock circuit. Playing clean doesn't mean you have to sound thin and wimpy.
· The gain in the drive channel is boosted way up to get great, natural tube compression for maximum sustain and dynamic response. A flexible tone circuit combined with very responsive gain and volume controls let you dial in just the right amount of distortion for the tone that you need. The overall sound is thick and crunchy, with that aggressive Marshall edge maintained.
· The channel switching is replaced to completely eliminate any interference between the clean and lead sounds. You'll no longer hear the clean channel bleeding through the lead channel when you're playing your leads.
12 pages text, 13 pages diagrams. Instructions only:$28.95. Complete kit: $93.00.
If you're using any type of digital effects processor, then you definitely need an effects loop. Rack mounted gear is simply not designed to plug directly into the front of the amp. If this is what you're doing now, then you're losing half of your sound. This is not to be confused with the simple preamp out/power amp in setup that some people think is a loop. This is a complete circuit unto itself that many techs charge hundreds of dollars for. It works in all Master Volume type amps that do not have channel-switching, as well as older amps that do not have Master Volumes. This mod requires that you add a tube to the chassis. Build it into your amp and get these features:
10 pages text, 9 pages diagrams. Instructions only: $12.95. Complete kit: $44.95.
Lots of old Marshalls went up in smoke because of their impedance selector switches. The plugs get old and loose and the terminals don't make contact as tight as they need to. Some of these things are so loose that they vibrate right out of the amp while you're playing! The result? Dead output transformer. Let this kit show you several ways of replacing the stock switch in a way that preserves the vintage appearance of the amp. Preserve the collector's value and avoid costly repair bills.
If you’ve always wanted to build your own amp, then read no further. Based on the JCM 800 model #2205 and #2210 heads, this is an ambitious project that rebuilds your Marshall from the floor up. Many detailed diagrams guide you through every step of the process and provide you with skills and information that you won’t find in any book.
Using a point-to-point style circuit board that you build yourself, you'll breathe new life into your Marshall as you tap into sounds that other players can only dream of. Each circuit in the amp is taken to its full potential, to give you two great sounding channels that far surpass the capabilities of the stock amp. This is a popular mod that I've done for many players who are searching for something way beyond what any stock factory amp can offer. You get:
Important note: this kit was recently upgraded and now includes additional information to modify the 50-watt amps as well as the 100-watt models.
17 pages text, 29 pages diagrams. Instructions only: $37.95. Complete kit w/FR-4 blank: $158.00. Complete kit w/circuit board: $188.00. Circuit board only: $34.95.
Any preamp sounds much better when it's plugged into a tube power amp. Why buy a separate power amp when you can access the power amp section of your favorite Marshall head or combo? These amps are true classics and provide that great vintage tone that we all know and love. The switching action of the special jack that you install allows normal operation of the head when you're not using a separate preamp. Designed for installation in amps that are built using point to point construction techniques. 3 pages text, 4 pages diagrams.
Instructions only:$7.95. Complete kit: $14.95.
These amps are relatively easy to find and are still reasonably priced. This mod works the same way as the one that's written for the vintage amps and also allows for normal operation of the head when you're not using a separate preamp. Designed for use in single channel Marshall amps that are built with printed circuit boards.
4 pages text, 4 pages diagrams. Instructions only: $7.95. Complete kit: $14.95.
Marshall amps have defined the sound of modern rock. They have a distinctive sound and attitude that's yet to be duplicated by any of the more modern amps.
What many people aren’t aware of though, is that many of the classic sounds captured on vinyl in days of old came from amps that were tweaked to perfection by inquisitive technicians. Players and collectors alike drive themselves crazy looking for amps that have the “magic” sound when in fact that sound can be easily created in an amp that they already own.
Whether you play an old Plexi from the ‘60’s or a JCM 800 from the ‘80’s, this kit is the one that you’ve been waiting for. The mods covered here can be used on any of the single-channel Marshall amps from this time period and the scaled drawings show how everything goes together in the pcb amps as well as the point to point models. Many of these techniques have been hidden from the public for years and are known only to the more elite technicians out there. Buy this kit now and create the sound that you've always wanted.
Important note: This kit was formerly titled: “Tweaking Vintage Marshalls”. A lot more material was recently added that deals specifically with the JCM 800 series amps, including schematics and pcb layouts for easy component location. I renamed it so that it would more accurately describe the information covered.
19 pages text, 17 pages diagrams. Instructions only: $17.95. Complete kit: $78.00.
Build your own boutique amp! Modify any amp! Those are only a couple of the things that you’ll be able to do once you’ve read through the information that’s contained in this kit. This new offering from Circuitrix cuts through years of theory and shows you only what you need to know to build, modify, or re-build your own tube amp.
If you’re like most people that are interested in building or modifying a tube amp, then you constantly read magazine articles, books, etc., only to be disappointed by incomplete information. The problem with most of what’s out there is that the authors assume that you know what they’re talking about. If you’re not a technician with a few years of school behind you and a couple of years on the bench, then you’re out of luck. Not so with The Missing Link.
Using classic amp designs as a basis to start from, The Missing Link provides a thorough explanation of the basic systems that are common to all amps. It explains how each section works and then shows you how to build each of them in a step by step easy to follow manner. At the end of the kit, you’re shown how to mix and match the circuits covered in various ways to create your own original designs.
Got a mediocre mass produced pcb amp? How about a low-cost budget amp that you got a good deal on? Until now, you’d be pretty much out of luck, as no one offers kits to mod them. That’s not a problem anymore though. If you don’t like the sound that you’re getting, then tear out that printed circuit board. Install a vintage circuit that’s constructed on a point-to-point style board that you build yourself and take control of your sound.
All the information that you need is covered in an easy to follow format, guiding you along every step of the way. For each circuit, there’s a schematic, a written explanation of what it does and most importantly a picture to show you what it actually looks like so that you can build your own. With such a varied approach, this kit has something for everyone, no matter what your level of experience is. This kind of coverage has never been seen before and it makes the information easy to grasp. Building your own amp has never been this easy, so join in the fun and buy The Missing Link.
Topics covered include:
32 pages text, 30 pages diagrams. Instructions only: $39.95. Complete kit w/FR-4 blank: $143.00. Complete kit w/circuit board: $173.00. Circuit board only: $34.95.
Here's a great new kit for all of you Strat players out there. This is a different way of wiring your guitar to gain access to some new sounds and solve some old problems, all at the same time. The biggest plus is that you won't lose any of your original sounds. The directions are extremely easy to follow, with pictures that guide you every step of the way. You get:
5 pages text, 2 pages diagrams. Instructions only: $6.95. Complete kit: $34.95.
Here's a mod that offers an option that no player should be without. Install this kit and you'll be able to set up any pickup combination for a rhythm sound with its own volume and tone setting and then instantly switch to the lead pickup for a solo. The switch is wired so that the volume and tone pots are completely bypassed in lead mode to get the full output and tone of the lead pickup. Hit the switch when your solo is over and you're back to your pre-set rhythm sound. When you're not using the switch, the guitar is completely stock and works just like it always did. The directions are extremely easy to follow, with pictures that guide you every step of the way. You also get:
5 pages text, 2 pages diagrams. Instructions only: $6.95. Complete kit: $34.95
Lots of people out there own and use this great pedal but very few have an idea of what it can really do! Buy this kit and you’ll get the grand tour of what’s inside of this box and how to modify it to suit your personal taste.
An extreme amount of detail sets this kit apart from anything else you’ve seen, including scaled diagrams that show where all of the critical components are located on the circuit board. All of the popular mods are in here as well as some things you’ve never seen anywhere.