Bass amp builders have labored for years to replicate the sound and feel of old SVTs and Hiwatts in more cost-effective, portable packages. A recent example is the 500-watt Classic 500 head from Sweden’s EBS.
The Classic 500 updates the earlier Classic 450 model in a smaller enclosure, though the design still allows plenty of space for heat dissipation. Removing the back plate reveals cleanly soldered circuitry and a stout toroidal transformer. In an era obsessed with class-D amplification, seeing the ol’ donut made me smile. The head weighs in at a manageable 31 pounds and has both a top handle and sturdy metal side handles for easy transportation.
The front panel is simple yet flexible. There’s a pre-EQ character switch—the pre-shaping filter found on many other EBS amps. Engaging the switch slightly scoops the tone, providing airier highs and a low-end bump. The sound-sculpting options may not be as extensive as EBS’s Fafner model, but the Classic 500 offers greater midrange flexibility. In addition to bass and treble shelving controls, there are dual semi-parametric midrange controls that let you punch, pop, and cut through a mix, or mellow out harsh frequencies.
Classic 500 Head
Pros:
A simple, versatile amp with good faux-tube tone.
Cons:
No effect loop. A tad pricey.
Tones:
Ease of Use:
Build/Design:
Value:
Street:
$995.95
ClassicLine210 Cabinet
Pros:
Cool looks. Clean tone. Great design.
Cons:
You may want to buy two.
Tones:
Versatility:
Build/Design:
Value:
Street:
$499.95
The drive control puts the “classic” in the Classic 500. It’s a class-A tube emulator that provides up to 30 dB of extra gain for a touch of tonal warmth—or seriously hairy bass sounds.
The rear panel includes two 4 Ω speaker outputs with Speakon jacks, wired in parallel. In other words, you can combine multiple cabinets, so long as they don’t go below a total resistance of 2 Ω. There is no effect loop.
We evaluated the Classic 500 with EBS’s new ClassicLine 210, an 8 Ω rear-ported cab that can be positioned horizontally or vertically and stacked with other cabs in EBS’s ClassicLine series. Weighing in at 36.5 pounds, the cab houses two 10" speakers and a 2" tweeter. Its rugged, multi-laminated plywood frame sports vinyl covering and a retro-looking grille.
Electric Bass Sweetnin’
With its EQ flat, the Classic 500 transmitted the sound of a 1964 Fender Jazz bass with immediacy and a balanced timbre that veered toward the highs. This tone sounded great on a horn-band gig, giving my fingerstyle bass lines a punchy foundation and a slight edge to cut through the mix. The character switch provides plenty of pop and booty. And when it came time to jam out on Sly and the Family Stone’s “Dance to the Music,” I cranked the drive to cop Larry Graham’s overdriven bass break. It would have been nice to have a footswitch to engage the drive, but it was easy enough to dial up with my right hand while hammering-on with my left.
Later, while playing a Nash P-style, I marveled at how that the amp’s midrange section seemed to transform my bass into Barry White. A low-mid boost and a slight upper-mid cut provided an articulate warmth and throaty growl reminiscent of the velvety crooner. This tone excelled in soft ballads and R&B classics.
Admittedly, I have yet to encounter any emulator that totally nails the sound and feel of playing with tubes. That said, the Classic 500 gets pretty darn close. By tweaking the drive and EQ, I found a tone similar to a ’70s B-15, with just a little bit of breakup. The notes may not blossom exactly as they do on a tube amp, but EBS’s emulator outshines many in its class.
To hear the Classic 500 with bigger cabs, I went for the gonzo, classic-rock setup and connected it to a pair of 4 Ω SVT 8x10s. I turned the master volume to 3 o’clock and pulled the 5th string of a Ritter R8 Singlecut. The sensation can only be compared to Michael J. Fox getting blown away by the giant speaker in Back to the Future. After an hour of noodling, jamming, and pissing off everyone around me, I can confidently report that the Classic 500 won’t leave you hungry for power.
The Verdict
The Classic 500 earns its name with classic style and classic tone. Pair it with the great-sounding ClassicLine 210 for a powerful rig that can handle almost any gig. It may not satisfy the pickiest of tube fanatics, but the amp’s versatile tones suit many styles. If you’ve been contemplating an EBS rig, this duo is a killer starting point.
Hi Jeff,
I have a ’66 Fender Bassman AB165 with the 2x12 cabinet that just isn’t getting me there. Not
enough high end, and I really need that famous Fender sparkle and shimmer. Unfortunately, when
I look to trade it in at a music store, they can’t even get me all the way to a silverface Princeton.
Money is an issue. Of course, modding is an option, but I’m concerned that if I’m not happy
with the basic tone now, I never will be. I tried taking the back off the cabinet to open it up,
but that didn’t really help. Should I try changing to such an extent that it’s something entirely
different? On the other hand, I can’t afford a boutique-quality, handwired amp any other way. I
have this amp because a friend helped me out by selling it cheap. I play blues and rock, nothing
heavy. Any ideas? Thanks!
—Shawn
Hi Shawn,
Well, you certainly have a nice
blackface-era amp there, and
the fact that your friend was
nice enough to give it to you
at an affordable price makes it
even cooler! However, I understand
your frustration with the
amp. While the Bassman was
designed for amplifying a bass
guitar, most players today use
them for guitar, since these
amps are able to get a nice
overdriven tone at a somewhat
useable volume. Many guitarists
play their 4Ω Bassman
heads into a 16Ω 4x12 cabinet,
thereby reducing the available
clean output power and
enabling smooth, creamy overdrive
at a substantially lower
level. Unfortunately, this sounds
like what you’re not looking to
achieve. But I believe we can
help you turn the amp into
something you’ll be much happier
with. Let’s start by examining
the amp’s front end.
The Bassman has two channels— the Bass instrument and Normal. The Bass channel is substantially different from the typical front end of any Fender blackface or silverface guitar amp, so we will leave this channel alone. Who knows? Maybe someday you’ll invite a bass-playing friend over for a low-volume jam, and you’ll actually use the amp the way it was originally designed: Amplifying one bass plus one guitar—a completely acceptable idea at the time.
Moving on to the Normal channel, the circuit and values are identical to the inputs of most blackface or silverface amps, so nothing really needs to be done here. One option you have, however, would be to have a midrange control installed. Simply substitute a 10k—or even a 25k—pot in place of the 6.8k fixed resistor at the bottom of the tone stack. This can easily be mounted in the No. 2 input of the channel without any modification to the chassis. I recommend your tech install a new single jack and remove the dualjack assembly as a pair so you can reinstall them as a pair if you wish to return the amp to stock.
Bringing a Blackface Bassman in from the Cold BY jeff bober
Now let’s move to the
mixer circuit and the output
stage. Though your amp is a
blackface, the AB165 circuit is
a transitional unit. Although
it was made just a short time
after the point CBS acquired
Fender—and prior to the
silverface-era Fender amps—
the new group of engineers
had started to “improve” the
designs of a few amps, this
being one of them. Removing
some of these “improvements”
should yield you a Bassman
much closer to the sound and
feel you expect from a traditional
Fender amp. These
simple changes can easily be
reversed if you wish to put the
amp back to stock condition.
Let’s start with the first stage of the Normal input. There should be a 500 pF ceramic capacitor in parallel with the 100k plate resistor connected to the plate (pin 1) of V3. (Note: this capacitor shows up on the AB165 layout diagram, but not on the schematic. As I said, it was a transitional time at Fender.) Removing this cap will put a bit more sparkle in the amp’s top end, (See photo 1.)
Next, we’ll move on to the
mixer circuit where the Normal
and Bass channels are combined
and amplified one more
time prior to the phase inverter
(driver) circuit. Here we find a
470k resistor connected from
the plate (pin 1) of V2 to the
input grid capacitor. This resistor
induces negative feedback
in this circuit and gives it a
bit of compression. On the
surface, this has the potential
to be a good thing in some
instances, but I feel that when
the volume is turned up, the
result is fairly non-musical.
Removing this resistor will
open the amp up a bit, again
improving its response and
sparkle, and making the whole
amp more musical when it’s
pushed. (See photo 2.)
Now, let’s tackle our final
and most drastic change.
There are a couple of alterations
that the CBS engineers
made to this circuit. The first
is the negative feedback loop.
I’m choosing to leave this one
alone, as I don’t feel that modifying
it would yield a great
enough result to warrant the
changes involved. The other is
an additional form of feedback
that was added to these amps.
(Boy, these guys were big on
negative feedback!) You’ll find
two 220k resistors connected
between the plates of the phase
inverter V4 and the plates of
the output tubes. These will
be easily recognizable, as one
end of each is connected to a
terminal strip. (See photo 3.)
Removing these resistors from
the circuit will substantially
increase the amp’s headroom
and make it sound larger and
feel more responsive.
Of course, there are additional modifications you could do to your amp, but I feel these three little changes will take the Bassman from having potential to something that you’re going to be much happier playing.
Jeff Bober is one of
the godfathers of the
low-wattage amp revolution,
co-founded and was
the principal designer for
Budda Amplification. Jeff recently launched EAST
Amplification, and he can be reached at
pgampman@gmail.com.These days, guitar speakers are available in a range of sizes from two or three inches, right up to 15". Smaller speakers are great for bedroom blasters and practice amps, where reduced output at low frequencies can minimize sound spillage between rooms and keep the neighbors sweet. If you’re like most, though, chances are you’ll be using 12" speakers for much of your recording and live work. But with an ever-increasing range of quality 10" speakers, and even some interesting 15" speakers available, one has to ask the question, “What role does speaker size play in the ‘relentless pursuit of tone?”
Inside the Mind of the Speaker Designer
Practically all of a guitar speaker’s constituent parts contribute in some way to its sonic signature. Chief among them are voice coil, magnet assembly and cone [but also influential are the suspension, surround, dustcap, cone treatments, etc.]. Each of these factors interacts with the others, together contributing to overall tone. These interactions, though in some cases very complex, are governed by certain principles of physics, in particular:
Output level [a.k.a. sensitivity] is determined by how efficiently the speaker converts electrical energy into movement of air.
Sound dispersion is controlled by the directional nature of high frequency sound and the tendency of certain cone shapes to focus the output signal in different ways.
 This laser doppler image indicates vibration modes within the body of the cone. |
For guitar speakers in particular, vibration “modes” within the body of the cone add much of the harmonic complexity and coloration that significantly contributes to great tone.
The speaker designer uses their expertise to find the right mix of all of these factors to hit a given “tone target.” Now, imagine we want to use a small speaker with a thin and light cone. There would be more intense vibration modes within this type of cone [compared to a cone of greater thickness, which would be more resistant to these vibrations], resulting in a richer, more harmonically complex tonality. However, use the same cone thickness with a larger diameter speaker and that cone might lack sufficient stiffness to withstand the proposed power handling, and could buckle under the force of the moving voice coil.
In this situation there would need to be some “trade-off” between tonality and power handling, requiring the designer to make both musical and technical choices to reach a desirable and workable solution. An experienced speaker designer will have the capability to identify the “right” choices to make in these situations, and use the opportunity to create a completely new sounding speaker.
What This Means For Tone
So, we see that attributes like size, harmonic complexity, power handling and high-note dispersion are clearly linked in the design process. Over time, the 12" speaker has come to be regarded as having the best balance of these attributes. However, 10" and 15" speakers can offer some alternative, interesting and even exotic flavors!
Good sounding 10" speakers can deliver a fast, punchy sound at wider listening angles with reduced “boom” on small stages. They can offer increased portability, reduced cost and the ability to push your amp into overdrive at reasonable levels without having drumsticks aimed at the back of your head. A well-designed 15" speaker can move more air so you can gig those wonderful little valve amps. The vocal range can be creamier, with extended low end and lots of detail and harmonic complexity, giving surprising richness to some otherwise scratchy-sounding guitar and amp combinations.
Which Size is For You?
It’s becoming more widely understood that changing speakers has a greater impact on tone than swapping guitar, pickup, or even amplifier. So ask yourself, why just one size of speaker? As players, all we need to do is select the right one according to situation, application … and desire.
Try this:
For the recording or practice session, why not try a small amp through a sweet, wellbalanced 10"?
At your big break support gig on the city hall stage, how about a wall of 4x12s?
Need to add some beef to your retro “plasticaster”? Break out a 1x15 cabinet.
What’s more, just as boutique amp makers have mixed different models to increase harmonic detail, you might even try and take this a step further by mixing 10", 12" and even 15" speakers to create that unique signature sound. But that’s another column.