Download Example 1
Flat - tube disengaged, no drive level, all EQ settings at noon.
Download Example 2
Contour EQ - tube engaged, contour at noon, two midrange controls at 2 o'clock 
Download Example 3
Tube/drive - tube engaged and drive at 11 o'clock, all EQ settings at noon.
Download Example 4
Flat - tube disengaged, no drive level, all EQ settings at noon
Download Example 4
Contour/EQ - tube engaged, contour at noon and two midrange controls at 2 o'clock
Clips 1-3 recorded with G&L L-2500 5-string bass with Black Diamond roundwounds using the neck pickup in active mode. Clips 4-5 recorded with '74 Fender Jazz with Fender flatwound strings slightly favoring the neck pickup. All clips were recorded with a Shure BG 3.1 mic placed about 6" in front of one speaker, into a Blue Icicle and then into GarageBand on a MacBook.
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One of the big side effects of G.A.S. is a false certainty that the next piece of gear will be the one. Over the years, I’ve switched amps and cabs more times than I can count, and they haven’t always been necessary changes. Sometimes, it’s the newest Best Thing. A few times, it’s been just the frustration of an off night. I’ve turned to Carvin to fulfill these G.A.S. needs over the years and have found the company’s gear to have been sturdy, reliable, feature rich, and value-priced.

A Two-Finger Carry
Enter Carvin’s new flyweight bass amp, the BX500, a 500-watt, Class D amp with a switching power supply, all rolled into a package that weighs less than six pounds. When you first pick up this amp, you might think it’s empty inside. The BX500 is a little wider and deeper than most of the ultra light amps out there these days—a trade-off for all the features that Carvin had to pack into its 3”x9”x14” metal box. There’s no handle on the box, so I’d have to say it’s a two-finger carry. There is a rackmount panel available, too, but a rack case would weigh more than the whole amp!

Changing Tonal Colors
The BX500 is a tone chameleon—chock full of options for altering its basic sound, making tones available that are quite different from its native sound with everything set flat. For tone shaping possibilities, the BX500 starts with the usual Bass and Treble knobs, offering 12dB of cut and boost on each. If that doesn’t do the job, you can get a quick tone fix with two bands of semi-parametric EQ offering broadly adjustable frequency centers.

Going one step farther, the BX500 offers a 9-band graphic EQ that’s switchable by either a front-panel toggle or by a footswitch plugged into the back panel. This can be a handy feature for soloing, for EQ’ing two different basses, or for changing up your sound for different musical styles. But there’s still one more EQ option: a Contour knob that scoops out your mids (around 350 to 500Hz) for slapping, or just a warmer tone. The specs show up to -15dB of mid cut, but I thought it was a subtle-sounding control, at least up to the halfway point when the real scooping begins.

Beyond tone, two more options let you make changes to the character of your sound. Somehow, with all that’s going on, Carvin was able to fit in a 12AX7 tube, which is switchable in/out on the back panel. I tried this feature with a few different basses and thought it was very subtle, more a difference in the feel of the attack, along with a bit more fullness on the bottom end. Because it’s all-or-nothing, you’re not able to get a tube grind kind of sound from it.

Which brings us to the second character bender: a Drive knob. Once again, don’t go to this knob for distortion, but for changes in both gain and harmonic content. Although this has a variable level control, you will probably notice the change of gain more than the change of the actual sound. I thought that between a quarter and halfway up, the Drive knob added some grit, growl and attack. To use it, though, the master volume must be lowered to compensate.

The Master Volume control does a lot in its first quarter turn, so that once the drive gets much beyond half, you barely turn on the master before getting plenty loud. If I had my druthers, I would make the master level turn up more gradually, so that it would still be usable when turned halfway up with the Drive knob in use.

Yes, Master
Unlike most amps, the BX500 has a Master, but not an input gain control or an input clip light. Instead, there is an active/passive toggle switch that pads down the input a little bit. The manual doesn’t have the spec for this, but this switch doesn’t produce a big change in volume and seems to accommodate active or passive basses in either position without changing the instrument’s tone.

Some might criticize the DI on the BX500, since it is pre-EQ only (most amps offer a choice of pre or post). I think it’s fine the way it is, especially with a front-panel level control. In most venues, the sound tech wants you to plug into an external DI box, sending just your instrument to the board, and generally prefers a pre-EQ send, since there’s a full-spectrum signal to work with.

Clean power is important, since nearly all contemporary bass amps use a solid-state power amp that gets ugly when distorted. If you want to add distortion to your sound, you do it via an effects pedal. The power output of a bass amp depends on the speaker load it sees. In general, a cab rated at 8-ohm impedance draws less power out of an amp than a 4-ohm cab. For the BX500, that means you’ll get 300 watts from an 8-ohm cab, the full 500 watts at 4 ohms (either one 4-ohm or two 8-ohm cabs). If you’re a slapper or play with a heavy attack, you’ll appreciate the one-knob compressor that lets you get the most out of the amp without distortion. I found the compressor to be reasonably smooth and effective. With just one knob, it’s easy to adjust on the fly.

Very few amps are rated for operation below 4 ohms, because they tend to overheat—a 2-ohm load is very demanding on an amp. Carvin found a way around this, with a switch that lowers the voltage sent to the amp so that you can run the amp at 2 ohms safely. Set up this way, the top power rating is still 500 watts, but if you happen to own a couple of 4-ohm cabs, you really can use them both together. I have never seen another company adopt this innovative solution.