Never kit-built a stompbox? It’s easy—if you let pro pedal maker Alex Guaraldi of CopperSound be your guide. Here, he takes you on a step-by-step tour as he assembles a Build Your Own Clone Classic Delay.
For this DIY adventure, we’re going to be walking through the steps of building the Classic Delay pedal from Build Your Own Clone (BYOC), a company that has been a big player in the pedal-kit game for quite a while. This is a little more complicated than building a fuzz or overdrive, so I’m going to explain the process with great detail. Let’s get started.
Tools You’ll Need for This Project
- Soldering Iron
- #2 Phillips screwdriver
- Wire strippers
- 8 mm (5/16") nut driver/wrench
- 10 mm (25/64") nut driver/wrench
- 1/2" nut driver/wrench
- 14 mm (9/16") wrench
- Flush cutters
- Small needle-nosed pliers
- Third hands
These tools are available via a variety of suppliers, including StewMac, Allparts, and Amazon.
Step 1: Review the Instructions
The kit as it arrives (Photo 2).
Each BYOC kit comes with a detailed set of instructions in the form of a PDF that can easily be printed out. The Classic Delay’s instructions can be found at http://www.byocelectronics.com/classicdelayinstructions.pdf. They are 32 pages long, and I suggest following their steps as you read this article. Here, I will refer to specific page numbers that correspond with the steps. I’ve also taken photos to coincide with the steps. Within the instructions, we find a table of contents, pictures of the fully assembled pedal, a list of parts included, and step-by-step instructions from internal population and soldering to external assembly. With any kit, always read the instructions carefully before you start building.
Step 2: PCB set-up
A lot of pedal builders use PCB jigs that are specifically designed to hold several printed circuit boards so that they can be easily populated and soldered. These jigs are great tools. However, they’re not something a casual DIY enthusiast will often have. Essentially, all we really need to do is elevate the PCB off of the working surface so that the leads of the components can pass through the bottom side of the PCB. This is most helpful with components that can be soldered from the top side of the PCB. “Third hands” or “helping hands” (Photo 3) are a good tool for this job. So, what can we do to elevate the PCB if we don’t have access to third hands? Simply turn the enclosure upside down and place the PCB perpendicular (Photo 4). This will elevate the PCB enough to allow the component leads to easily pass through.
Step 3: Populating Resistors and Diodes (instructions page 9)
When populating PC boards, we typically like to work lowest to tallest in regards to the seating. Seating is how far above the PC board the component rests. Resistors and diodes sit pretty low to the PC board, so populating them first makes sense.Resistors: Remove the resistor from the paper ribbon, bend the leads (Photo 5), and place them through the corresponding pads (Photo 6) as directed. (A pad, by the way, is the term for the designated surface area of a component’s electric contact point.) A good practice is to populate all resistors of the same value before moving on to the next value. Populate all 1k resistors, then all 10k resistors, and so on.
Reading resistor color bands can be confusing, so don’t forget the reference guide on page 7 of the instructions. Here, you will find a detailed breakdown of each value and its corresponding 5-band reading (i.e. 1k = brown/black/black/brown/brown). Once all the resistors are placed, we can go on to the diode.
Diode: Next, we need to place the diode. Just like resistors, remove the diode from the paper ribbon, bend the leads, and place them through the corresponding pads. Diodes are polarized and need to be oriented a certain way (Photo 7). Be sure to match the diode to the outline on the PCB, as shown on page 10 of the instructions.
Step 4: Solder Resistors and Diode
Fire up the soldering iron! Once the iron is up to temperature (650 to 750 degrees Fahrenheit, depending on how fast you work), it’s time to get to work. Resistors and diodes can easily be soldered from the top side. So no need to flip the PCB over. Place the solder tip to the pad and feed the end of the tip a bit of solder. What we’re looking for here is solder that covers the entire pad, encapsulates the lead, and has a nice shine to it. Think of it like a shiny Hershey's Kiss shape (Photo 8). Repeat this step for every part. If you’re new to soldering, you should consult our concise guide to soldering, online or in PG’s October 2015 issue.
Soldering tip: Shut the iron off between population steps. Use a small, tabletop fan to blow the solder fumes away during soldering steps. Quick tutorial videos on YouTube are also of benefit here, for builders new to soldering.
Step 5: Trim the Leads
Next, place the PCB upside down to expose the leads (Photo 9). Using flush cutters, trim the excess leads (Photo 10).
Step 6: Soldering IC Sockets (page 11)
Place the 8-pin and 16-pin IC sockets into the corresponding pads on the top side of the PCB. We need to solder the IC socket pins from the bottom side. This means flipping the PCB over without having the IC sockets fall out. For this, I like to use a small piece of foam (Photo 11).
I place the foam on top of the PCB (Photo 12), then flip the foam and PCB simultaneously so the foam is below the PCB and the bottom side of the PCB is facing up (Photo 13).
For this soldering step, we’ll want to solder ONLY 1 pad and then flip the board over to ensure that the IC sockets are sitting flush. If the IC sockets are not flush, go back to the bottom side and reflow that solder pad while pressing the PCB downward and keeping it parallel to the work surface. Solder the remaining pads (Photo 14).
Step 7: Soldering the Voltage Regulator (page 12)
Place the voltage regulator into the three corresponding pads, while keeping mindful of the orientation. The flat side needs to match the outline on the PCB. Now, we’re ready to solder. This can be done from either side. Flush-cut the excess lead and we’re done here (Photo 15).
Step 8: Soldering the Trim Pot (page 13)
Place the trim pot (Photo 16) into its corresponding pads. For the trim pot provided, I found it easiest to solder the two exposed legs from the top side (Photo 17) and then the remaining leg from the bottom side.
Step 9: Soldering Ceramic and Film Caps (page 14)
Place all ceramic (pill-shaped) and film (red) caps into their respective locations. Again, use page 7 of the instructions as a reference for identifying the correct capacitors (i.e. 100n film cap, which may say “104” or “.1” or “u1” on the body). We’ll need to solder the pads from the bottom side. So, once again, the piece-of-foam trick can be your friend here. Flush-cut the excess lead and we’re done (Photo 18).
Tip: An alternate method would be to bend the leads away from each other so they stay in place when the PCB is flipped over (Photo 19).
Step 10: Soldering Electrolytic Caps (page 15)
Let’s do the same thing here as we just did in Step 9. One thing to note is that electrolytic capacitors are polarized and need to be populated in the correct orientation. This is denoted on both the PCB and the component itself. On the PCB, the positive pad is denoted by the square pad. On the electrolytic capacitor, the positive lead is the longer leg. Additionally, the negative lead of the cap also corresponds to the white strip on the body (Photo 20).
So, let’s go ahead and populate the caps and solder them with either the foam trick or by bending the leads. Flush-cut the excess lead and we’re done (Photo 21).
Step 11: Battery Snap and Hook-Up Wire
This DIY kit offers a battery option for those that feel so inclined. (See page 17 of the instructions.) For this step, we’ll need to connect the battery snap to the PCB. Before soldering, we’ll want to first feed the two wires through the holes directly below the solder pads. These holes act as strain relief for the battery snap and have + and - signs next to them (Photo 22). Then, simply solder the red wire to the positive (+) pad and the black wire to the negative (-) pad (Photo 23).
Next, we need to cut and strip the included wire (page 18). We need four 2.5" pieces of wire, and one 1.5" piece (Photo 24).
Place the 2.5" wires into the top side of the solder pads for in, out, and the two courtesy grounds—all handily marked. Then, solder from the bottom side. Do the same for the 1.5" wire going to the ring pad (Photo 25).
Tip: If painting the enclosure is desired, this is the last chance you’ll have to do it. After this, there will be components mounted to the chassis.
Step 12: Install DC Jack (page 19)
Place the DC jack into the large hole on the back heel of the enclosure and tighten the nut using a 14 mm (9/16") wrench (Photo 26).
Step 13: Potentiometers and Status LED (pages 20 and 21)
The included instructions for this next part have you mate the PCB to the inside of the enclosure. This will help line up the pots and LED. However, afterwards it will make soldering the remaining wire more difficult. Here’s a trick we can do that gives us the benefits of using the enclosure to help with pot alignment without needing to take the PCB out afterwards to solder the remaining wires. What we’ll want to do is simply use the face of the enclosure to hold the pots and set the LED height. Additionally, we can use the flush cutters to help balance the PCB (Photo 27). Be sure to have the long lead of the LED mate with the square pad, then solder away!
Step 14: Final Hook-Up Wire
My steps continue to vary slightly from the instructions throughout the rest of the build, so you might want to do a side-by-side comparison. Let’s finish the wire for the DC jack next. Cut and strip three 1.5" pieces. These need to be placed into the three power pads at the top of the PCB marked -, +, + , as in Photo 28.
Next, cut and strip five more 1.5" pieces. Place these in the footswitch pads at the bottom of the PCB marked 1, 2, 5, 7, 8 as shown in Photo 29.
Last wire! Cut one 1.5" piece. Only for this one, strip half an inch off of one side (Photo 30). Place the short-stripped side into the footswitch pad labeled 4.
Step 15: Footswitch prep
For the footswitch, we need to jump lugs 3 and 6. To do this, we’ll use the remaining wire. Place the footswitch into the correct hole on the face of the enclosure. Then, cut a 1" piece of wire and strip half of it. Feed the exposed wire through lug 3 and into lug 6 and then solder both (Photo 31). Cut the excess wire.
Step 16: Insert the IC
Now, we’re ready to insert the integrated circuits into their respective sockets. These need to be placed in the correct way, and there are two ways to identify them. Pin 1 is the top left leg of the IC—which is the rectangular black object in Photo 32. These legs are marked with a small dot in the top left corner or the upside of the IC is marked with a debossed half circle.
Step 17: Mounting and Final Soldering
PCB: Now for the real fun! We’re ready to start inserting chassis-mounted components. Let’s start with the populated PCB. Place the PCB with the three pots lining up with the drilled holes, place the pot washers on the shafts, and then tighten the pot nuts using a 10 mm (25/64") nut driver/wrench, for the results in Photo 33.
Footswitch: Now that the PCB is securely tightened, let’s go ahead and do the same for the footswitch. Remove all hardware from the footswitch bushing except for one nut and the lock washer (Photo 34).
Feed the footswitch through the footswitch hole, making sure that the footswitch has the two poles that we soldered together facing the bottom left (Photo 35).
Next, place the plastic washer onto the bushing (optional), and tighten the hex nut with a 14 mm (9/16") wrench (Photo 36).
Lets go ahead and solder the footswitch wires to their respective footswitch poles (Photo 37). See the instructions’ page 26 for pole-numbering reference.
Tip: Solder from the top row down—i.e. 1, 4, 7, then 2, 5, 8.Another tip: Remember that the wire for pole 4 also connects to pole 9.
Step 18: DC Jack
Next, we’ll need to solder the three wires that go to the DC jack, as explained in page 22 of the instructions. Start with the middle wire, since it sits the lowest and will be easier to get at without the other two wires in the way (Photo 38).
Step 19: Audio Jacks
The last chassis-mounted components are the two audio jacks. Let’s do the stereo input jack first. Go to page 24 of the instructions to see how these jacks are oriented. The lock washer goes on the bushing first, then gets placed into the hole to the left of the DC jack. Then, place the washer onto the bushing and tighten the hex nut with a 1/2" nut driver/wrench.
Follow the same steps for the mono output jack. And then, it’s the final soldering step: Solder the wires to the appropriate lugs on the audio jacks (Photo 39), as on instructions page 28. Then, finally, place the knobs on, tighten them down, and we’re done!
Our columnist recounts what he’s learned about getting the sound of a projection cone to an audience, and his ultimate solution: two mounted mics and his faithful Super Reverb.
In my July 2022 column, “Acoustic Guitars and Fender Amps,” I talked about using acoustic 6-strings with classic black-panel amps—particularly the bigger models with wide EQ possibilities. This month, let’s take it a step further and talk about Fender amps and resonator guitars. I will share what I have discovered by experimenting with various microphones, pedals, and more.
In a resonator, the metal cone underneath the front plate functions as a base for the bridge saddle and vibrates like a loudspeaker to project sound. Because of the instrument’s directional character and ease of feeding back, resonator guitars are difficult to use in live bands with loud stage volume. The goal is to get enough volume resonator onstage and in the room without feedback. Since it’s an important part of the instrument’s character, it’s necessary to capture some of that metal-cone voice within an overall balanced guitar tone that sits well in the mix. And you need to be able to achieve this in a way simple enough to reproduce the same tone night after night, and focus on your music, not technical problems.
The easiest way to mic a resonator guitar is to place a microphone on a stand about a foot in front of the guitar and run the signal into the mixer. But this pure acoustic route only works well in low volume situations—due to feedback—and requires you to play sitting down or standing still.
“Because of the instrument’s directional character and ease of feeding back, resonator guitars are difficult to use in live bands with loud stage volume.”
You can also use the type of clip-on microphone (often used for violin) made by Neumann and DPA, among others, to make you mobile, but if you get too close to the monitors or mains, feedback ensues. I recommend the microphones that come with a preamp and volume dial, to give you the most control. If you use one of these, point the mic directly toward the metal cone. Finding a nice tone will require some experimentation.
Another option is a piezo pickup. Some newer resonator guitars come with factory-installed piezos. It’s not very difficult to install a passive piezo yourself. You need to file and sand the bridge piece, detach the metal cone for wiring and soldering work, and, finally, drill a hole in the guitar where the jack plug goes in through the strap button. Getting the string tension correct over the entire length of the bridge saddle is the key to success. Lately, I have used hard oak as bridge material, which creates a smooth and mellow tone with bronze strings.
The author’s resonator “kit.”
Piezo pickups are less prone to feedback than acoustic microphones, so they are better for high-volume stage scenarios. But piezo pickups alone will not fully capture the tone of the resonator cone, so if you’re looking for more of that, add an acoustic clip-on microphone. That’s what I do. Both the piezo and the clip-on go to my Fender Super Reverb, and I use the normal channel for the feedback-sensitive acoustic microphone while the piezo goes to the vibrato channel with reverb. For dirty tones, I sometimes use an overdrive pedal for the piezo pickup. There are independent EQ and volume settings on both channels.
The third and last microphone technique I have experimented with is a humbucker. I bought one from 12 Bar Blues Pickups that is only 6 mm tall and built specifically for resonators. It fits nicely under the strings with enough clearance. The advantage with a passive magnetic pickup is obviously the simplicity. The installation process is easy if you simply tape or glue the pickup to your guitar and let the wire run externally on top of your resonator’s body. The kit I bought contains a small volume and tone box with jack input, and requires no battery. The result is, essentially, a hollow-body electric guitar suited for pedals and regular amps. It is also more resistant to feedback than both piezo and acoustic microphones. When I want to add some of the “bluegrass” flavor of the resonator cone, I add the acoustic microphone as mentioned earlier.
One drawback with conventional magnetic pickup technology is that bronze strings have a lower output, since bronze is less responsive to magnetic fields than nickel. I have kept the bronze strings on my resonators because of the great tone. To get even output on the bass strings, the bridge height measures a little higher on the bass side than the treble side.
So, there we have several different techniques for capturing modern resonator guitar tones, including a few options with guitar amps. Now, go experiment!
Using a contact mic on your acoustic guitar has many advantages—and can open the door to some adventurous experimentation.
For example, during a chamber music concert, I placed a contact mic under the chess board as we reenacted, move for move, the legendary 1972 World Chess Championship Game 6 of Bobby Fischer and Boris Spassky, while rice grains were dropped on the board as the rest of the ensemble made an ongoing soundtrack. (I highly recommend watching HBO’s 2011 documentary, Bobby Fischer Against The World.) In short, it’s my go-to initial technique for making totally new sounds, textures, timbres, samples, and sound design that I incorporate into my music. Tighten up your belts, the Dojo is now open.
Before we start, there are many benefits of using a contact microphone. It can pick up sounds that are not audible to the human ear. For example, if you attach the microphone to a metal surface and strike it with a mallet, you will hear not only the sound of the mallet hitting the metal, but also the vibrations of the metal itself. Which is exactly how Ben Burtt got the blaster sound effects for Star Wars—by hitting a certain radio tower’s support wire (guy wire) in the Mojave Desert.
“It’s my go-to initial technique for making totally new sounds, textures, timbres, samples, and sound design that I incorporate into my music.”
Recently, I showed our students at the Blackbird Academy how to create new samples and sounds by attaching a contact mic to the outside of a 5-gallon water jug, then pouring water inside and hitting the side of the jug while gently swirling the water. We eventually ended up with an entire “water jug” drum kit.
Another benefit of using a contact microphone is that it can eliminate unwanted background noise. Because the microphone is only picking up vibrations from the surface it is attached to, it is less likely to pick up ambient noise in the room. However, because it is sensitive to vibrations, it may pick up unwanted sounds from handling or movement. Also, it may not capture the full range of frequencies that a traditional microphone would capture.
Lastly, they really come in handy for older vintage acoustic instruments that you may want to leave in their original state and have the flexibility to mic from any position without harming them.
Um … How Do I?
To use a contact microphone, you need to attach the microphone to the surface you want to capture the sound from. I only use Loctite Fun-Tak Mounting Putty because it is non-permanent, leaves no residue, and is non-tarnishing, malleable, and non-toxic. I simply place a tab of the Fun-Tak on the back of my contact mic and then mount it to whatever I want to record.
Check out Fig. 1. You can see I’ve attached my Zeppelin Labs Cortado MkIII mic ($159 street) to the headstock of my National Estralita Deluxe. This gives me that piezo/electric sound that I can in turn reamp or process with plugins, etc.
Be sure to experiment with different placements all over the instrument to find the sound you are looking for. Ever wonder what it might sound like inside your slide when playing slide guitar? Tape the mic on the top of your slide and play away. But don’t stop there! You could also place it on electronic kids’ toys that make noise (toy pianos, baby shakers, celeste, handheld electronic games), or pitched percussion, like kalimbas, log drums, vibraphones, and even cymbals. Or, think way outside the box—literally. Mount it on all kinds of cups, glasses, bowls, buckets, doors, and windows. Or on glass shower doors (outside the shower of course!), or the inside of your car windshield the next time you wash your car or it rains, flagpoles on windy days, park slides, merry-go-rounds, swing sets, and basically anything else you can imagine.
After you get some great source sounds, head back to the studio, keep what you like and process the sounds with reckless abandon. Until next time, namaste.
Our much-loved former columnist Jeff Bober returns to explain how to check and reset the bias of your amp’s output tubes—and delivers some potentially shocking warnings about a few common but dangerous techniques.
Hello again, Premier Guitar readers! It’s your old bud Jeff here, author of the once popular Ask Amp Man column. Editorial Director Ted Drozdowski asked me if I would be interested in writing about bias, and, of course, I said, “Sure, I know a thing or two about that!” So here I am, temporarily returning to these pages. Now, let’s get started.
What exactly is bias? Bias is prejudice in favor of or against … oh wait, wrong kind of bias. I think he wanted me to write about bias in a tube amplifier, which is far less polarizing.
Bias, as defined in the RCA Radiotron Designers Handbook, is “voltage applied to the grid [of a tube] to obtain a desired operating point.” Well, that is the most basic explanation, but for the most part it is good enough and pertains to the majority of tube output stages in our favorite tube guitar amps.
Setting the bias adjustment controls to these listed voltages in no way guarantees that your amp is properly biased.
Besides “applying” a voltage to a vacuum tube, however, biasing can occur in another way as well. There are quite a few amplifiers, such as a Vox AC15 and AC30, any of my Budda and EAST designs, and even most of the early, low-wattage amplifiers of the tweed era that use what’s known as a “cathode bias” design. This is where the current flowing through the tube (which attains the aforementioned “desired operating point”) is not set by the voltage “applied” to the grid of the tube, but is instead set by the resistor in the cathode leg of the tube. It’s a bit more complicated than that, but the result is an amplifier whose output stage is “self-biasing.”
Most amplification devices, including transistors and even preamp tubes, need to be “biased” in order to perform properly, but this type of biasing is fixed in the design parameters of the circuit. In the case of the preamp tubes in your guitar amp, bias is based on the value of the cathode resistor, among other things. But that’s enough design theory for today. Let’s get back to the core task of biasing the output tubes in most guitar amplifiers.
First, the bias voltages you see listed on many schematics, such as 52V on a black-panel Fender Twin Reverb or 51V on a Marshall 100W Super Lead schematic, are merely approximations of the voltages that should be expected in that area of the circuit. Setting the bias adjustment controls to these listed voltages in no way guarantees that your amp is properly biased. Tube bias is also dependent on the high voltage (or B+) applied to the plate of the output tube, which can vary within tolerances of the transformers as well as in the AC line voltage fed to the amp. (This is why amps can sometimes sound better in one room or club than others.)
But even more important to understand is that tubes produced in different factories across the globe will bias up differently! What I mean by this is, if you properly bias a set of output tubes—let’s say 6L6s made in Russia—and then you swap them out with a set made in China, in the same amplifier without changing the setting of the bias control, the end result will almost always be a different bias reading. This is why it’s always best to have checked and reset the bias whenever output tubes are replaced. Now, how do we do that?
The Preferred Method
There are several different ways to measure output-tube bias current at idle. The safest method is to use what is commonly called a bias probe (Fig. 1). This is a device that is inserted between an output tube and its socket. (I typically make my own bias probes, but if you simply search “bias probe” online, you’ll find plenty to choose from. If you already own a multimeter, you can simply purchase the probes, but there are also options to purchase a full system with either a digital or analog meter, should you need it.) This device breaks the connection between the cathode (which is the metallic electrode from which electrons are emitted into the tube) of the tube and its ground connection, and inserts a small value resistor in between. It then allows the voltage across the resistor to be read. The resistor is typically 1 ohm and the resulting voltage drop across it is in millivolts (mV), so no chance of shock here. This provides a true and accurate measurement of the actual current flowing through one tube. Then, you set your bias and you’re done!
But even more important to understand is that tubes produced in different factories across the globe will bias up differently!
Ah, but wait! How do you set your bias? Let’s learn a bit more. Most tube amplifiers, if they are not cathode-biased designs, have some way to adjust the output-tube bias. One longstanding exception to this are most Mesa/Boogie amps. The bias voltage in these amps is not adjustable, which is why Mesa suggests only purchasing their tubes for their amps, because they are designed to fall within the acceptable bias range for their amps. This adds a certain degree of confidence for owner servicing, although, of course, it limits your options.
Let’s take a look, however, at a typical Fender or Marshall bias control. Most older Fenders have a pot with a slot for a screwdriver mounted to the chassis in the area of the power or mains transformer, while most older Marshalls have their bias pot mounted on the circuit board. (You might want to go online to look at schematics for your amp to help you find it.) Either way, this is where you’ll make your adjustment.
To get started, you’ll most likely need to pull the chassis and place it in a stable work environment. Insert the bias probe device between one of the tubes and the socket (Fig. 2). Make sure all the volume controls are set to zero, turn the amp on, and let the tubes warm up. It’s also good to try to have a load on the speaker jack—whether a speaker or an appropriate resistor or load box. This is not 100 percent necessary for just setting the bias to a particular number, but sound checking is one of the ways I like to make the final adjustments, so being able to connect the speaker to the chassis while it’s on the bench is certainly a necessity for me.
Now, where to set the numbers? There are certainly more than a few opinions floating around on the interwebs about what optimal bias settings are. Some engineering types will tout 50 percent maximum plate dissipation or 70 percent maximum dissipation, and while it may look good or make sense on paper, I’ve heard the result of guitar amplifiers designed by the book to optimal specifications … and to me they sound, well, less than optimal. It may work in the hi-fi world, where perfect sound reproduction is the goal, but guitar amplifiers are in the sound production business, so it’s a bit different. (In the most basic terms, maximum plate dissipation is the amount of power the plate of the tube is designed to deliver.)
Different types of output tubes have their own acceptable range of bias current. There are so many variables at play that there is no “correct” number. The plate voltage in the amplifier, the output transformer’s primary impedance, and the country of origin of a tube all factor into how it interacts with the voltage and output transformer to define what the optimal bias current will be. Below are the average ranges for some typical octal output tubes:
• 6L6: 25–35 mA
• EL34: 30–40 mA
• 6V6: 18–25 mA
• 6550: 35–45 mA
• KT66: 30–40 mA
These should be the ranges in which these tubes will perform and sound the best, and they can be accurately measured with a digital multimeter. The best way for you to decide what setting is best for you is a combination of the reading on the meter and your ears! Using the bias control, set the bias to somewhere in the ranges given above (Fig. 3) and play the amp. Note: Some amps will act funny and develop horrible noises (parasitic oscillations) when a bias probe is in place while the amp is being played. If this is the case, you’ll need to remove the bias probe each time you play the amp.)
Move the setting a couple mA in one direction or the other and play again. Don’t expect extreme changes; that’s not what we’re looking for. Listen for subtle differences. Is one setting a little more or less harsh? Is the bottom end too soft or flubby? Is the amp as clean as you want it? Sometimes these little subtleties are what make one amp sound and feel better than another!
Most older Fenders have a pot with a slot for a screwdriver mounted to the chassis in the area of the power or mains transformer, while most older Marshalls have their bias pot mounted on the circuit board.
Also, you should be doing this at the volume you would typically use onstage or in the studio. You may not notice much change if your volume is at 1, but you want to optimize the amp for the way you will be using it.
Eyes Wide Open
Knowing the ballpark bias numbers is good, and adding your ears is even better, but I also like to see what I’m hearing, so I always incorporate an oscilloscope when I’m setting the bias on an amp. I mentioned crossover distortion above, and when it comes to setting up amps for today’s pedal-hungry players, I find that setting the bias to where there is just a hint of crossover distortion at full output is what works best. Fig. 4 is what that looks like on the oscilloscope. This keeps the amp very clean and makes most pedal users happy.
By the way, here’s a mini primer in crossover distortion. In a push-pull output stage, which is found in most amplifiers with two or more output tubes, each tube (or pair of tubes) is responsible for amplifying at least half of the audio signal. If the tubes are not biased properly, one tube (or pair) will stop amplifying before the other tube (or pair) start amplifying. This will create crossover distortion. Proper biasing will allow the two halves to interact correctly. It’s like a nice firm handshake between both halves.
Beware These Old-School Methods
Let’s look at a couple popular methods that I do not recommend, but are worth discussing because they are, nonetheless, common. The first is: With the amp off and output tubes removed, use a multimeter to measure the resistance of each half of the primary side of the output transformer. This would typically be from the center tap to each side of the primary winding.
In the most basic terms, a transformer is a bunch of wire wound around a steel core. On the primary side of an output transformer, the center tap is the electrical “middle” of this long length of wire. This is typically where the high voltage is applied. The ends of this length of wire are connected to the plates of the tube, thereby applying the high voltage to the tubes. As an example, typically in most Fender amps, the center tap is red, and the ends of the primary windings are blue and brown.
Next, install the output tubes, turn the amp on, and measure the voltage drop across each half of the output transformer with the amp at idle in operational mode (Fig. 5). Voltage divided by resistance will give you the DC current through the tubes. For example, 1.17V / 15.8R = 0.074, or 74 mA. The numbers I used here were actual measurements in one side (one half) of a 100W amp using four output tubes (two per side). So, divide the 74 mA by two, and you get an average of 37 mA per tube.
Next, you can try the shunt method. This requires a multimeter that can read DC current in milliamps (mA). Connect one meter lead to the center tap of the output transformer and the other lead to the output transformer’s primary side. Typically, in most amps using octal tubes (6L6, 6V6, EL34, 6550, KT88, etc.), this will be pin 3 on any output tube socket. Turn the amp on and, in operating mode at idle (i.e., volume off), measure the current across that half of the output transformer. For example, if your measurement is 72 mA and it’s an amp that utilizes four output tubes, the current measured is for two of those tubes, so once again divide by two to arrive at 36 mA per tube.
I’ve heard the result of guitar amplifiers designed by the book to optimal specifications … and to me they sound, well, less than optimal.
Both of those methods are very old school and still in practice, but I wouldn’t use either for two reasons: 1) I don’t believe they’re very accurate, and 2) they’re dangerous! You’re probing around inside the high voltage area of the amp, and one slip will either take out a fuse, take out a tube, take out your meter, or, worse case, let you know exactly what 450V DC feels like! So, although these methods are used, let’s just say no here.
Some Personal Insights
I’d also like to add a little personal experience to this procedure, based on decades in the biz. Back in the day, when I began servicing and modifying gear, guitarists were regularly playing 50- and 100-watt amps. (Everybody looked at me like I had three heads when I came out with the 18-watt Budda Twinmaster, but that’s a whole other story.) There were some overdrive and distortion pedals around (now all vintage), but certainly not the pedal proliferation we have now, so players were pretty much guitar, cable, amp … go! In these situations, I would most times run the tubes with a pretty hot bias so the amp would be fatter and overdrive a bit earlier and easier, as a decent percentage of the overdrive was developed by pushing the output tubes. As time went on, output attenuators became more popular, so amps could be pushed hard, but at more manageable volume levels. That was still a good scenario for a hotter bias of the output tubes in high-power amps. Eventually, players started playing lower-power amps, so they could open them up and get great output-tube distortion at lesser volumes. The problem is that hotter-biased low-power amps tend to get mushy and have less definition when pushed hard, so a more moderate bias setting is preferred here—just enough so there is no crossover distortion. Move up to today’s scenario and you’ll find that almost all overdrive and/or distortion is typically coming from a pedal. In that case, an amp is nothing more than an amplification device for pedals.
So, that’s what I’ve learned about tube-biasing from my decades of experience. But the bottom line is, there is no absolute right or wrong settings when it comes to biasing an amp. Keep your ears open and go with what sounds best to you.
Using templates when recording makes a big difference in streamlining your workflow, and will leave you more time to get creative.
Hello and welcome to another Dojo! This time I’d like to focus on the benefits of using templates in your recording and mixing process. I’ll also show you some ways in which you can increase your productivity by using customized templates for your particular workflow regardless of what DAW(s) you use. Whether you’re recording a live band or a solo artist, you can create templates that include the necessary tracks, processing, and routing setups to meet your unique requirements. Tighten up, the Dojo is now open.
Over the last 30 years, digital audio workstations (DAWs) have revolutionized the way music is produced and recorded, making it easier to create high-quality recordings from the comfort of your own home. With so many options now available, it can be challenging to streamline the recording process and maintain consistency across multiple sessions. This is where templates—pre-configured session setups that can be customized and reused to simplify the recording process—come in.
The main point here is to create a template that works for you. I have found that the more specialized the template, the less flexible it becomes for use in other scenarios. For example, a 48-channel mixing template with specific plugins, buses, and other routing assignments won’t be a first choice when recording a power trio. I think the important thing is to recognize the type(s) of work you do and make different levels of templates accordingly. By creating various kinds of templates that include all the necessary tracks, plugins, and settings, you can ensure that each recording or mix session starts with a consistent foundation, allowing you to focus on the creative process rather than technical setup.
“By sharing templates, you can ensure that everyone is working with the same setup and settings, making it easier to collaborate and share ideas.”
Creating a new tracking session in your DAW from scratch can be a time-consuming process, especially if you’re working with a large number of tracks or complex routing setups. Using templates allows you to quickly set up your session and get to work, without having to waste time configuring settings or searching for the right plugins. I find this particularly useful when starting a new project that involves recording multiple songs with the same artist or band.
Typically, I create the session’s tracks and buses, assign, route, and organize my signal flow, in-the-box or outboard (Fig. 1), and get sound levels from each musician by making adjustments at the mic first, then add EQ and compression as needed. Once all that is done, I save the session as a “tracking template” with the artist/band name and date. When we’re ready to move on to the next song, I pull up the “tracking template” and save it as a “new session”! Now I have the same organization of track count, routing, etc., and I am able to repeat the process for each song moving forward.
Mixing It Up
The same logic applies when moving to the mixing stage. I’ll create a new template focused on advanced signal routing and incorporate things like console and tape emulation (if it wasn’t tracked through a console), side-chain options, routing folders, and instrument groups specific to that project. I found that using one-size-fits-all, highly specialized mixing templates end up being overbuilt and I waste time parsing out only what is necessary, as well as making sure that it is not draining my RAM and CPU resources.
Using templates can also be beneficial when collaborating with other musicians or engineers. By sharing templates, you can ensure that everyone is working with the same setup and settings, making it easier to share ideas and tracks. This can be especially important when working remotely, as it can help ensure that everyone is on the same page, even if they are not in the same physical location.
Creating templates can also help future-proof your recording process, ensuring that your recordings remain consistent and of high quality as your needs change over time. By creating templates that can be easily updated or modified, you can adapt to new recording technologies or workflows without having to start from scratch. This can help you stay ahead of the curve and ensure that your recordings are always of the highest quality.
Finally, you can create templates that use console emulation on every channel, aux, and mix bus. There’s Universal Audio’s LUNA API Vision Console Emulation Bundle ($559 street), Neve and API summing plugins ($149 street) and many other possibilities from Waves NLS, and Slate Digital’s Virtual Console Collection ($149).
Regardless of the DAW you use, taking the time to create some different types of templates will save you time and help keep you and everyone involved in the creative state of mind. Until next time, keep creating! Namaste.