A terrific twosome or a terrible twinning? It all depends on how you tame your treble.
Rein in those icy high frequencies with these handy tips.
Classic vintage Fender amps are renowned for their clean, shimmering tones. However, dialing in the āsweet spotā isnāt always straightforward, especially when you're playing on a new or borrowed amp. Pair these amps with Fender guitarsāalso known for their brightnessāand the combination can sometimes result in ear-piercing treble and overwhelming volume. An amp thatās too powerful or an unsuitable guitar pairing can easily derail the musical moment youāre trying to create. So, controlling treble is crucial, particularly with louder amps.
In this article, Iāll share my experiences with Fender amps and how Iāve tamed treble issues through guitar tweaks, speaker swaps, amp modifications, and pedals. My goal is to help you achieve those glorious vintage Fender tones without losing your earsāor your audienceāin the process.
Backline Bargaining
Iām extra cautious about bringing my brightest Strats or Teles to gigs with rented backline amps. Newer Deluxe Reverbs, for example, can be particularly tricky with dialing in a smooth tone. These amps often feature bright ceramic speakers and the EQ options are limitedāthereās no bright switch to dampen the top end and no mid knob to add warmth.
Hereās what I do: I start by turning down the tone knob on my Okko Twinsonic overdrive pedal, which is very transparent. My old Ibanez Tube Screamers naturally rolled off much of the high end, making them easier to pair with brighter amps.
I also adjust the microphone placement set up by the sound crew. The tone gets brighter the closer the mic is to the center of the speaker cone. I angle the SM57 slightly and aim it closer to the outer edge of the cone, leaving a 3ā4 cm gap from the grill cloth. Larger 12" or 15" speakers are more forgiving in this process, while smaller 10" speakers are less so. Iāve encountered challenging amps, like a Super Reverb loaded with 10" JBL speakers featuring aluminum dust caps. These amps sounded much harsher through the PA than they did on stage, making mic placement even more critical.
Dimming the Bright Caps
Bright caps are key components in shaping an ampās treble response. On the Deluxe Reverb, the bright cap is always enabled, which can make brighter guitars sound harsh, especially at low volumes or when using fuzz pedals. Cranking the amp helps by adding more upper mids to the mix.
For my own Deluxe Reverbs, I sometimes disable the 47 pF bright cap or, more often, install a 25k mid pot on the back panel to add warmth. It depends on the tones Iām chasing.
Smaller amps like the Fender Champ and Princeton donāt have bright caps, which naturally gives them smoother tones. But if they sound too dark or muddy, you can add a bright cap. I installed a 100 pF bright cap on my 1966 Princeton Reverb (which has a Jensen C10N speaker from the same year, though not original to the amp). After experimenting, I settled on a 47 pF cap for just the right amount of clarity.
If youāre up for a bit of DIY, experimenting with bright cap values can significantly shape your tone. Black-panel and silver-panel Fenders typically use 120 pF bright caps, with exceptions like the Deluxe (47 pF) and the Princeton and Champ (none).
Guitar Tweaks for Warmer Tones
Your guitarās setup can also make a big difference. Thin strings combined with pickups set too close to the strings can result in a thin, overly bright tone. Hereās how I address this:
ā Lower the pickups slightly. I start with a 2ā2.4 mm gap on the high E string and 2.4ā3.3 mm gap on the low E, measured between the pickup pole and the string when fretted at the highest fret. Then, I fine-tune by ear to balance output across pickup positions.
ā Use thicker strings for a warmer, fuller tone. I tune my guitars down to Eb to deepen the sound and increase sustain. Keep in mind, though, that this can create a looser, flabbier bass response on smaller amps.
ā Hotter pickups add mids and bass, naturally reducing treble dominance. Alternatively, lowering the resistance of the volume pot can smooth out the tone by filtering high frequencies. However, changing pot or cap values will alter how your guitar responds when rolling down the tone or volume knobs.
Speaker Swapsā
Finally, and perhaps most importantly, speakers play a huge role in shaping your tone. Swapping speakers or experimenting with extension cabinets is one of the most effective ways to adjust treble, mids, or bass. Iāve written extensively about this in previous articles, but itās worth emphasizing here: The right speaker pairing can make or break your tone.
I hope these insights help you conquer any treble troubles and coax balanced tones from your Fender amps. Happy tinkering!
To measure the bias on his Deluxe Reverb, our columnist lays his amp face-down on the floor for easy access to the bias pot and power tubes.
Here are a few tips to get you started on your way to becoming an old-school Fender amp tech.
Back in 1995, when my journey with vintage Fender amps started, I knew little about tube amps. Over 30 years, Iāve gradually learned the hard way how to acquire, play, service, and give advice. If tube amps are to become a hobby for you, I recommend learning some basic maintenance. Youāll be better off in terms of time and money, and even more important, the knowledge about how circuits and components affect tone will give you a wider array of sounds to play with. But where should you start?
Hereās my list of relevant topics that you should be able to master with a little patience and curiosity. My goal is to get you started on your journey to becoming a Fender amp handyman. The topics are sorted by gravity, and youāll need in-depth studies from reliable sources on each topic. On my website, fenderguru.com, Iāve tried to explain things easily for musicians, but there are many other good Fender amp resources out there.
Safety. First and foremost: There are lethal voltages inside tube amps, much higher than in transistor ampsāeven after powering some of them off. Learn how to discharge DC voltages before opening an amp. In my websiteās buyerās guide to vintage Fender amps, I have laid out a procedure on how to safely power off and power up these amps by inserting tubes in a specific order.
Speakers. I strongly recommend learning impedance and wiring methods and experimenting with various internal speakers and cabinets. The mathematical formula 1/Rt = 1/R1 + 1/R2 calculates the total impedance for two speakers coupled in parallel; Rt is the total impedance, and R1 and R2 are the impedances of the two speakers. Remember that all Fender amps can tolerate an impedance mismatch from -50 percent up to +100 percent.
Pots and jacks. Fixing scratchy pots is a common task for all amp owners and is usually solved by a rotating exercise that freshens up the oxidized metal surfaces inside the pots. If itās sticky, get yourself a contact cleaner like WD-40 and spray inside the pot.
āWhen you get more advanced, you can calculate specific bias currents based on measured plate voltages and a specific tubeās dissipation factor.ā
Reverb tank. Reverb failure is common and often explained by bad phono cables or plugs. It is easy to learn the mechanics of the reverb tank by simply unplugging everything, changing cables, and opening the reverb tank to look for detached reverb springs and broken soldering joints.
Replacing power tubes and adjusting bias. A power tube requires a correct combination of plate voltage and bias current to operate safely and at full power levels. Since there are different tubes, component drift/variation in caps and resistors, and different voltages in houses and buildings, some tube amps come with an adjustable bias pot.
You need a bias-meter tool to measure bias currents or voltages when replacing power tubes, or diagnosing an amp that lacks clean headroom or has nasty distortion. When you get more advanced, you can calculate specific bias currents based on measured plate voltages and a specific tubeās dissipation factor. Until then, a general rule is to aim for 35 mA for 6L6 amps (except for the Vibrolux, which has a higher bias current at 38 mA) and 22 mA on 6V6 amps. Use your ears, too!
Caps. Old, dried-out electrolytic capacitors should be replaced for both tone and safetyās sake. With a soldering iron, itās very easy to replace each of the 10 to 11 caps in a black- or silver-panel Fender amp, one by one. Be careful with the polarity, and make sure to drain out all DC voltages (see āSafety,ā above).
Preamp tubes. Replacing preamp tubes is easyāno bias adjustment is required. Replacing preamp tubes systematically can solve your problem or help you narrow it down. You then need to learn the function of each preamp tube and which channel they serve. If you want to modify your amp, simple tube swaps can easily change the behavior of your amp, like altering the threshold where your preamp or power amp starts breaking up.
Transformers. I rarely come upon damaged transformers, but sometimes I swap them to get a bigger and firmer bass response, or if I want different speaker impedances. By looking at the soldering job, cutting of isolation, wire lengths, and layout, I can easily spot an amateurās work. To prevent all kinds of safety, hum, and interference problems, a transformer replacement must be done cleanly and robustly. The risks are high.
Understanding the signal chain. If you have more complex problems that tube replacement doesnāt solve, you must learn how to inspect an amp and isolate problems to various circuit functions. This will require you to learn some circuit theory and schematics. The good news is that since Fender amps are all very similar, once you learn to work on one, you can easily learn to work on them all.Our columnistās beloved Fender Super Reverb head goes under the knife.
Vintage Fenders are some of the best-sounding amplifiers around, but from time to time, they need a bit of love to give up the goods. Here are the top issues youāll encounter with your black- and silver-panel Fender amps, and how to fix them.
Trouble and worrying are part of a vintage tube amp ownerās life. In this article, I will try to teach some basic troubleshooting for vintage Fender amps. It will only require a little practice, patience, and, most importantly, curiosity, which to me is the single most important skill in lifeāwe can accomplish great things by reading, seeking advice, trying, failing, and not giving up. So, letās start!
As usual, I will refer to the silver- and black-panel Fender amps, but everything is applicable to earlier amps as well. I will often refer to tubes: On a Deluxe Reverb, for example, the tubes are referred to from V1 to V9. Always consult your amplifierās schematic to confirm these placements.
No Reverb
The reverb tank is the most delicate component of these amps. The springs, wires, and soldering joints are thin and weak, and the reverb cables and plugs are also easily damaged, as they are exposed on the backside of the chassis.
First, check the plugs on both the amp and reverb tank. Unplug and switch the input and output to see if the previous player made a mistake. Often, the plugs are damaged and not conducting current, or the inner wire or outer insulation are broken. I recommend replacing old cables with new, vintage-correct ones if you suspect the slightest cable or plug issue.
āTrouble and worrying are part of a vintage-tube-amp ownerās life.ā
A bad V3 or V4 preamp tube may also cause reverb loss. If replacing tubes or reverb cables does not help, you should try hooking up another ampās reverb tank to verify whether you have an amp or reverb tank issue. The reverb springs may also have jumped out of position and need to be re-attached. I recommend refreshing soldering joints here.
No Vibrato
First, the footswitch must be plugged in for the vibrato to work. If you donāt have one or suspect that itās malfunctioning, you can either buy or make yourself an āalways-onā phono plug that is shorted internally with solder. A bad vibrato-driver tube may also cause vibrato loss, which is fixed easily by replacing the V5 with another 12AX7. If none of this helps, a tech should open the amp and inspect the vibrato tube circuitry, and/or replace the opto-oscillator component.
Blown Fuse
Pull all the tubes before replacing a blown fuse. If the fuse blows repeatedly without any tubes installed, a tech should be involved for inspecting the filter caps/resistors, power transformer, and the high-wattage resistors on the power-tube socket pins.
If the pilot lamp light is on when all tubes are pulled out, start inserting tubes one by one from the V1 rectifier tube. Turn power/standby on. If the fuse blows, the rectifier tube is bad. Then, insert both power tubes and turn power/standby on. If the fuse blows, you need new power tubes, and possibly new screen and plate resistors. Continue this procedure for each of the preamp tubes until you identify corrupted tubes that draw too much current.
Weak Tone
Check speaker cable(s) and speaker terminals. I find it useful to connect to a second ampās speakers to determine if itās the speakers or an amp that is the problem. (Remember to turn off or set the amp in standby whenever speakers are disconnected.)
Then, verify that the tubes are working by following the previous āblown fuseā procedure. Look for loose power-tube sockets causing bad connections by gently pushing them around in the socket. If speakers, tubes, and sockets are working fine, a tech should further inspect the amp.
Distortion, Reduced Volume, or Weak Bass
When playing powerful 40-watt amps at low volume, it can be difficult to hear if only one tube is working. If one of the power tubes is malfunctioning, you will experience distortion and farty bass. Non-matching power tubes can also result in distortion and reduced clean headroom, which is detected by measuring with a bias meter.
Preamp tubes in wrong positions may also affect volume response and cause an amp to distort too early or too late. Check all tubes and replace them one by one with fresh ones as you listen for tone changes. Sometimes we prefer the wrong tubes because we like more distortion. (My tube strategy is to replace tubes only when they fail entirely. I donāt mind weaker power, rectifier, or phase-inverter tubes since these amps are more than loud enough.)
Rattling Noise
Loose screws and nuts can cause rattling noise and should be inspected and tightened regularly, including on the chassis, baffle board, tilt-back legs, speaker, handle, and anywhere else. If the baffle board is warped and worn so that the screws are not tight, I never hesitate to install a new, solid-pine baffle. This usually improves tone and robustness compared to old, warped MDF baffles
Our columnist is really passionate about cleaning up his tone.
Our columnist breaks down why Leoās original designs are still the benchmark for pristine guitar sounds.
Itās time to discuss a favorite topic of mine: the Fender clean tone. Iām a big fan of pristine guitar tones, and I think it might be the reason why I got into Fender amps in the first place. So, in this column, Iāll break down and explain what creates the beautiful, crystalline tone in vintage Fender amps, and share which amps are best for capturing these huge, squeaky-clean sounds.
Among my music friends, I am known for advocating these tones. Sometimes my bandmates want more distortion and growl from my guitar, but I proudly resist and argue that the music we create profits from a clearer guitar tone. Itās not about volume and distortion; itās about melody, rhythm, and dynamics. Personally, I find it more interesting to hear guitarists with clarity, where I can identify single notes and what they are doing. Itās much harder to play clean, and the transparency forces us guitarists to consider more carefully what we play.
Tone and music are definitely matters of personal taste. What someone finds naked and thin, others will find clear and articulate. Let me therefore explain my definition of āclean tone.ā A good, clean tone means clarity and little distortion. Clarity is achieved when there is a certain balance between the frequencies. There must be enough sparkle and brightness together with a firm low end. In my definition, you can also have some distortion as long as you have enough clarity to hear single strings in a chord, which some define as a ābell-likeā tone. Muddy or overwhelming mid and bass frequencies will spoil this clarity. I like punchy guitar sounds, and for that we need muscle and power from large power-amp sections and larger speaker cabinets. But again, there must be enough sparkle and treble attack to balance that big low end.
The black- and silver-panel Fender amps excel in this area. Fender designed these amps specifically to support the music style of the 1950s and ā60s: Whether it was folk, country, rock, or surf, the guitars were supposed to be bright and clean. The amps therefore had to produce a sound that was both clean and loud, often without PA systems.
There are several reasons why these Fender amps sound the way they do. Letās dive into the most important factors. Firstly, the tone stack and EQ section play a significant role in creating a scooped tone with few mids. Most AB763 Fender amps have 250 pF, 0.1 Ī¼F, and 0.022 Ī¼F caps (treble, mid, and bass, respectively), controlled by 250k bass and treble pots and a 10k mid pot (or a fixed 6.8k resistor in amps without the mid pot). If you alter the value of the mid resistor or insert a larger coupling cap after the preamp section, you will get more, and earlier, breakup. If we look at the preamp sections of the AB763 amps, there is no tube gain stage, whose purpose is to introduce distortion. There are only the necessary tube gain stages to mix and lead the signal to the power amp section.
āFender designed these amps specifically to support the music style of the 1950 and ā60s: The guitars were supposed to be bright and clean.ā
The power amp section is equally important. The AB763-style amps have dual power tubes in a Class AB push-pull configuration which has significant clean headroomāmore than single-end Class A amps. The fixed-bias design provides more headroom than cathode bias, which creates sag and less headroom. The efficient long-tail phase inverter and the negative feedback loop are also used to minimize clipping. Finally, using American-style speakers in the open-back cabinet design of the black- and silver-panel combo amps will enhance bright frequencies and tame the mids and low end. All these details point to one conclusion: Fender designed the AB763 amps to achieve the cleanest possible tone.
For me, the cleans of a Super Reverb are especially fantastic. The four, lightly driven 10ā³ speakers produce a scooped sound with great dynamics and touch sensitivity. The full set of EQ controls, robust power amp, and large transformers work together to give you both sparkle and a firm low end, even at high volumes. The Pro Reverb and Princeton Reverb, however, will struggle to stay clean when pushed. The relatively small-output transformers are a bottleneck in these amps, and they both lack the important mid control to tame the bass and mids. The Pro Reverbās boomy 2x12 cabinet gives a flabby bass response, and the Princeton Reverb has a cheaper and inefficient phase inverter. This means that these amps can play clean only at lower volumes. If you read my previous articles on these amps, you will find easy instructions for how to improve the clean headroom, if thatās what you want.
If itās natural distortion youāre after, the best black- or silver-panel Fender amp is the AB165 Bassman. But thatās a different story weāll come back to later.
Our columnist is back to balance the force with a look at the top qualities of old-school Fullerton noise-makers.
Last year, I wrote a column listing the top 10 annoying things about vintage Fender amps. Now, I seek to rebalance the equation, and will share my list of reasons to love them.
There are countless reasons why simple, vintage Fender amps are still the tool of choice for many working musicians, both onstage and in the studio. I suppose my list is also colored by the fact that I am an electrical engineer, just as Leo Fender was. I have traded and serviced them for almost three decades. As usual, I will mostly refer to the black-panel and silver-panel era of amps from the 1960s and ā70s.
1. Circuit standardization
The amp techs among us may have noticed how similar the electrical circuits are in the various Fender models, especially the popular black-panel Deluxe, Vibrolux, Pro, Vibroverb, Super, Twin, and Showman. Many of us use the nickname āAB763ā amps because they are based on the same electrical circuit design, and some are almost identical on the inside. Yes, there are some differences, but apart from the power levels and size, they follow the exact same recipe with the tube layout, preamp section with tone stack, the long-tail phase inverter, the class-AB push-pull power tube design, fixed bias, negative feedback loop, and so on.
So, the tonal differences between the black- and silver-panel-era amps are explained by cabinet size, speaker configurations, speaker type, and power levels. Once you learn how to work on one model, you can work on them all.
2. Circuit simplicity
The first time I opened a Fender amp and inspected its innards was in 1998 when I got my first vintage one, a 1965 pre-CBS Super Reverb. I was surprised by how simple and organized the circuit was. The few components were laid out in patterns and functional sections, and the wires were cut in perfect lengths and bent nicely, tying everything together in a way that was easy to understand when I followed the circuit layout diagram. Simplicity means fewer things that can go wrong. These qualities also make maintenance easier for amateurs and enthusiasts.
3. Low-cost physical construction
Back in the day, Fender was concerned about cost and weight, and as a result, there was no high-end selection of materials or advanced mechanical features. If you need to repair or rebuild something, you donāt have to rebuild with absolute vintage correctness to obtain the original Fender tone. If, for example, an MDF baffle board is damaged, which tends to happen to amps with multiple heavy speakers, I always use thicker pine plywood when cutting out a new board. The tone remains pretty much the same, while robustness is drastically improved. This also goes for cabinet pieces, back plates, screws, and nuts. Do what Fender did, and use what you have available.
4. Tube mods
As a player, I like simple tube-swap mods, and as an engineer, I am impressed at how vintage Fender amps handle different tubes, or even allow you to pull some tubes out. Did you know that you can remove V2, V3, V4, and V5 in an AB763 amp, and the normal channel will still work?
My favorite tube swaps are a 12AX7 in the phase-inverter position for less headroom; a 12AU7 as a reverb driver for better reverb control; 6L6s in place of 6V6s in the Deluxe Reverb for cleaner headroom; and a single 6L6 in the Princeton Reverb for less headroom. There are plenty other tube swaps that you can learn about on my website, fenderguru.com, or in previous articles here at Premier Guitar. You risk malfunction and burned tubes and components if you insert the wrong tubes, so be careful and trust only valid sources.
5. The big lineup
In my list of problems with Fender amps, I pointed out a few amps that I would have recommended that Leo Fender cut out to reduce production complexity and cut costs. However, I do dig the big lineup of different amp models, from small practice amps to huge stage amps. You can pick the exact tool according to your taste and needs, and as mentioned earlier, all of them share the characteristic Fender clean toneāitās just that some are much louder than others.
6. The clean tone
For me, the clean tone of an amp is everything. This is my number-one reason why I love the old-school Fender amps. They were designed as clean, natural tone platforms, for the simple purpose of amplifying the sound of your guitar, bass, or keyboard.
But a proper analysis of Fenderās clean tone requires a column of its own, so stay tuned for the next Silver and Black!