Speaker Geeks: Strange Brew

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.