A close-up look at the author’s Fender Vibrolux, with a 12" Celestion Alnico Gold on the preamp side of the amp and a lighter, 10" neodymium Jensen Jet Series on the other.
How to expand classic Fender amp sounds with different speaker configurations.
As you know, replacing or augmenting the speakers of your Fender amps is the easiest way to organically change your guitar tone. So, let’s discuss some alternative speaker configurations for classic Fenders. We’ll also explore some basic knowledge about resistance, current, and power distribution along the way, which will enable you to safely experiment.
If you are replacing or adding speakers, it is important to verify that all speakers are in phase and that you wire the plus and minus terminals correctly. Otherwise, the speakers will cancel each other out and the result will be a thin, weird tone without much bass or character. This rule applies to all speakers in the main amp and in extension cabinets. For all the examples in this column, I will refer to 8-ohm speakers wired in parallel, if not explicitly mentioned otherwise. I will also use both the terms “impedance” and “resistance,” which are commonly used in these conversations, even though the correct term for speaker resistance is impedance. Got that?
Now, let’s use a Deluxe Reverb as an example. The most common trick to create a bigger tone and more spread from a Deluxe is adding a second cabinet with a 12" speaker. The Deluxe has just enough power to drive them both. However, I’ve found that the Deluxe’s 22 watts is not enough for adding a 15" speaker. The bottom end gets too loose and farty. For that option—which features a full clear bottom end and opens up the array of overtones—I would typically recommend a bigger, 35- to 40-watt amp. But there is an option for adding a 15" speaker to a lower-powered Deluxe. You can replace the 6V6s with 6L6GC tubes for more power. Then, adding a 15" speaker makes sense.
“It is important to verify that all speakers are in phase and that you wire the plus and minus terminals correctly.”
Here comes a few even-more-advanced tricks with the Deluxe Reverb. The first: Replace the original 1x12" baffle with a 2x10" baffle for snappier low-end response, more sparkle, and a more scooped tone. It is very easy to cut out a solid pine board and staple grille cloth onto it. With two 10" speakers, the total speaker impedance also changes from 8 to 4 ohms, and will suit the 6L6GC tubes better, since they have a lesser output impedance than the 6V6 tubes. After that mod, if I want to play at lower volumes, I unplug one speaker and use the Deluxe Reverb as a single 1x10".
An even more creative and rarer variant is to use both 10" speakers together with a 15". In this setup, you have to wire the two 10" speakers in series and connect the 15" via the external speaker output. The amp will then see two resistance branches in parallel:
- Branch 1: the two 10" speakers = 8 ohms + 8 ohms, for 16-ohms resistance.
- Branch 2: the single 15" speaker = 8-ohms resistance.
The current always wants to follow the path of least resistance, so the second branch with the 15" speaker will get twice the amount of power and current as the first branch. And since there are two speakers in the first branch, that total branch’s power is divided equally between them. This results in a roughly 67 percent + 17 percent + 17 percent power distribution for the three speakers. This is a healthy and good-sounding balance, since a 15" speaker requires and can take a lot more power than a relatively tiny 10" speaker. Be aware that you must not use the amp in this configuration without the 15" plugged in, or you will damage the power tubes. The amp expects a 4-to-8-ohm impedance with the 6L6GC tubes. The two 10" speakers alone at 16 ohms is too far outside the safe operating range.
I will also briefly mention a change-up for the 2x10" 35-watt Vibrolux Reverb. If you want more punch and a bigger low end from this model, you can replace one of the 10" speakers with a powerful and efficient 12". I have had great fun fitting a 12" Celestion Alnico Gold on the preamp side of the amp and a lighter, neodymium Jensen Jet Series Tornado 10" on the power transformer side of the amp, where there is less physical space for a big speaker magnet. You now have three power levels: the 10" alone, the 12" alone, or both together for maximum punch. I can even add another 12" external speaker cabinet via the external speaker output for a mega spread on big stages. If I want to add a 15" extension speaker, I prefer to disengage the internal 10" and use the 12" and the external 15" together. My favorite modern 15" is the Eminence Legend 1518. It is impressively responsive. Also, it balances nicely with a classic vintage black-panel Fender tone.
I hope these ideas and tricks inspire you to experiment with speakers.
As with all things guitar, a little patience can yield big dividends.
Think about the last time you bought a new pair of shoes. When trying them on in the store, you probably thought, “These feel pretty good, but I bet they’ll feel amazing once I get them broken in.” So you bought the shoes and wore them every chance you could. Eventually they folded and creased in all the right spots to conform to the shape of your foot.
Now think about the last time you bought a new speaker. Maybe you tried it out, but didn’t immediately like it. Or perhaps you’ve never bought a new speaker and are hesitant to do so because you’re not sure what to expect. All right, what’s the connection between speakers and shoes? The answer is simple: Just like footwear, new speakers need to be broken in. If you didn’t know that, you’re not alone. Many guitarists don’t realize that new speakers need time to break in before they reach their ultimate tonal potential.
Before we can understand why this is necessary, we must understand what needs to be broken in. There are two main parts to consider: the cone and the spider. You probably know what the cone is, but may not be familiar with the term spider. The cone connects to the front of the voice coil. The spider is the term for the suspension that attaches the rear of the coil to the frame. (To see an exploded diagram of a speaker, check out “Alnico or Ceramic … What Gives?”)
For a speaker to function, the voice coil, cone, and spider must all move in and out as one piece. The electric signal from your amplifier causes the voice coil to move back and forth, creating an electromagnetic motor. The spider holds the voice coil in place, and the cone projects the sound outward.
The cone is traditionally made of paper, while the spider is usually a mesh-like material that has been formed into a specific shape. When brand new, these two components are very stiff, and this affects the speaker’s sound right out of the box. This stiffness can create a bit more high-end fizz and somewhat strangled lows, or very little highs and unfocused lows.
The part of the cone where the most movement takes place is the outer edge, or surround. This is the primary focus of speaker break-in, as this is where the most physical change will occur. It’s not a change you can readily see, but relates to microscopic breaks in the paper fibers. This occurs to a lesser extent in the spider, but the main emphasis is on the surround.
So how do you break in a speaker? Players and techs use many methods, though it all amounts to the same thing—getting the cone to move, which causes those creases and breaks to happen. This process necessarily takes time, our most precious commodity, which explains why some folks run recorded music through a speaker, while others use a Variac to send a 60-cycle hum into it. Some folks chemically “age” their cone with fabric softener (though that seems like cheating to me).
Personally, I don’t care for any of these methods. I like the good old-fashioned approach—simply playing guitar. It makes sense to feed a speaker the same frequencies it will receive in the future, and the variability in your playing won’t cause the same heat buildup as a Variac. The break-in period depends on the speaker and how it’s designed. To get a speaker mostly broken in, I recommend playing through it at a moderate volume for 12 to 20 hours—but it could even take 50. As the creases work into the cone, the unwanted fizz or strangled sound will diminish or disappear, and the speaker gets a little louder.
Sure, a speaker might not sound exactly like you want at first, but it will only get better and better the more you play it—just like those new shoes once you wear them for a while. Best of all, this “play it in” approach gives you a reason to practice—something I always encourage.
What happens when a Deluxe Reverb meets an Electro-Voice EVM12L?
After seeing a recent video by Paul Rivera on the subject, I’ve become fascinated by the interesting relationship between the Electro-Voice EVM12L and the blackface Fender Deluxe Reverb amp. I’ve known Paul since filling the chief amp-tech position at Valley Arts Guitars that he vacated back in 1979, so I rang him up to find out more. Rivera helped establish Valley Arts as the go-to hub for pro players in Southern California, and it is here that my career in amp design began to take shape.
On the phone, Paul basically reiterated what he’d said in the video and, in typical Rivera fashion, he encouraged—make that challenged—me: “Go get a Deluxe and an EV and do some measurements.” That I did, and with the kind cooperation of jazz/funk king Paul Jackson Jr., for the speaker, and Joe Gamble, a frequent Fryette demo-video producer who provided an excellent early ’60s Deluxe, I was on my way.
Before we take the deep dive, let’s look at the context in which the Deluxe came into being. Intended as a student model, and hitting the market just prior to mass adoption of distortion as a sonic device, the Deluxe Reverb came with a low-powered 12" speaker fitted with a 20-ounce magnet. This cost-conscious production choice no doubt presumed that in those days one simply didn’t turn the volume past 3 or 4. However, as players began to explore the territory beyond 3, they also ran up against the consequences of doing so. Enter the speaker upgrade.
The iconic blackface Deluxe certainly has its own thing going, and although the current ’65 reissue comes stock with a 100-watt Jensen C12K, much of the original Deluxe mojo was defined by its strikingly underpowered speaker. Naturally, the minute you replace that with even a moderately more robust unit, the sonic signature that the stock, small-motor speaker is hiding comes roaring to the fore. I should note that for this experiment, I started by installing a custom, Fryette-spec Eminence P75 speaker. With its reasonable weight and typical power-handling capacity, this speaker turns the stock Deluxe into a much more versatile and giggable combo than before. It also provided a nice point of reference, being a well-known and fully documented entity, for this exercise. If you’re inclined to experiment, having a solid baseline is extremely important.
During the Valley Arts heyday of the ’70s and early ’80s, replacement speaker options were rather limited and mostly aimed at increasing clarity and reliability. The JBL D120 and Altec 417B were two of the most popular options of the era. The D120 was notable for its bold midrange and penetrating top end—a prominent feature of the Allman Brothers’ guitar sound, as fitted into a Marshall 4x12 cab. D120s had a distinctive—and to some ears, annoying—nasal chirp due in part to the signature aluminum dustcap. You may be surprised to know that those D-series speakers were alnico types, and for all their robust engineering, were fairly easy to blow in an open-back cab.
Rumor has it that the Allmans took the backs off their JBL-loaded 4x12 cabs in those days, not only because, as many believed, that made it easy to replace speakers, but because the D120s projected so much better than the stock Celestions that the band needed to dissipate some of that sound pressure out the back. This, by the way, also made for a much more ambient playing experience onstage. I should know. I once tried running a 100-watt amp into a 4x12 Greenback cab with its back off. While the reflected sound was a boon to my live gigging setup, I promptly blew 3 of the 4 speakers. Since these high-performance replacement options were out of my price range at the time, the originals got re-coned and I reinstalled the back on my 4x12 cab.
Also featuring alnico magnets and metal dustcaps, the 417B was made famous by Carlos Santana. Mick Taylor used 417Bs with the Stones in the early ’70s, and later Randy Rhoads used them with Ozzy. Both the D120 and 417B had strong personalities, and they were as sought after by some as they were shunned by others for being somewhat overbearing on top.
Electro-Voice was already in the game with their SRO series, but with the advent of the EVM12L, there at last was an alternative that was supremely reliable and sonically appealing to a wide variety of players. As such, the 12L became widely adopted as the dominant workhorse speaker—so much so that it soon found its way into just about every amp available at the time, including the very portable Deluxe Reverb, due in no small part to Rivera’s tenure at Valley Arts.
With its very large magnet, relatively low inductance, and aluminum-wound voice coil, along with the stiff cone, large dustcap, and compliant suspension, the EVM12L seemed to be just the right recipe to counter the flubby low end, scooped mids, and brittle top end one finds in the stock Deluxe with a typical speaker “upgrade.” That assessment still holds surprisingly true, though installing a 20-pound speaker in a 40-pound amp seems counterintuitive today. Contrary to what one might expect, the 12L brings out the pleasing sparkle and warmth of the Deluxe without sounding too piercing on top or too muddy on the low end.
After a fair bit of research and testing, and having spent considerable time delving into speaker inductance and reactive loads, I ran some of my observations by Eminence speaker designer Anthony Lucas. Here’s what he had to say:
“Inductance is certainly a part of what you’re hearing with the EVM12L in the blackface Deluxe, but not everything … maybe not even the most significant part. With its 20-ounce magnet and lightweight paper cone, the stock speaker is both coloring and limiting what the amp can do. It’s much more a part of the tone-creating process, like it or not, because this speaker has more limitations and likely a lot more peaks and dips in response. With its pro-audio cone, the EVM12L offers flatter response, minimal-to-no speaker breakup, and a much broader frequency-response range (down to 55 Hz). The 12L can handle the amp’s low-frequency range without getting muddy and breaking up, and it retains the amp’s clarity. You basically get out what you put in because with its 2.5" voice coil and 80-ounce magnet, the speaker is essentially overkill for the application and it delivers as full a range as physically possible.”
That last tidbit—“as full a range as physically possible”—offers a clue to the nicely tailored top-end response of the 12L-equipped Deluxe. In short, the substantial moving mass embodied in the 12L’s cone/voice coil/suspension assembly is certainly going to inhibit extended top-end response, and this is borne out in the speaker’s graph. You see an unusually smooth curve from 100 Hz to 2 kHz, a nice presence peak at 5 kHz, followed by a steep drop-off with little of the top-end nasties normally present in a guitar speaker.
The reason I find this combination so intriguing is that paired with an amp where much more attention is paid to the balance and synergy of the individual components and speaker, the EVM12L can be surprisingly disappointing. Yet in the Deluxe, the 6V6 power tubes driving an otherwise modest output transformer are allowed pretty much free rein to do their magic, while being massaged and refined by a speaker whose engineers probably never considered this a likely application for their considerable design effort.
In the ’70s and ’80s, when LA’s studio A-listers were schlepping their gear to several sessions a day, and probably a club gig at night, this versatile, high-performance little package—beefed up with a few of the must-have Rivera mods of the time—was considered practically indispensable, and helped launch the portable powerhouse-amp revolution.
So, should you consider installing such a massive appendage into an otherwise reasonably portable combo amp today? Only your chiropractor knows for sure, but if you can fairly well establish that any sonic roadblocks in your amp are likely caused by the stock speaker, it’s certainly a worthwhile and potentially enlightening experiment.