Weber MASS Attenuator

The past several years have brought about an era of reinvigoration for vintage non-master volume style amplifiers and I believe some of the reason is due to the fact that there are some great choices for attenuators out on the market today. Everyone knows that there is nothing that can harmonically compare to the tone of a quality vintage tube amp cranked up with its warm power tube distortion running along with its preamp gain. But the trick has been trying to capture that great tone at lower volumes and that’s where an attenuator can come in very handy.

For those not familiar with how attenuators work, they simply connect between an amplifier’s output and the speakers and they can then limit the amount of power that goes to the speakers and control the overall volume. The designs and practice of attenuating dates back to at least the late ‘70s, but it’s only been within the past five years or so that reliable designs have emerged that don’t affect the tone to the extreme degree that earlier designs were plagued with.

The Weber MASS attenuator is one of the newest entries in the market. Weber is well-known to diehard tone guys as a manufacturer of vintage style speakers that more accurately reproduce the classic tones that guitarists are searching for than today’s common reissue models do. It’s no surprise then to find the Weber MASS employs an actual speaker motor in its design as its load device.

The MASS is offered in various models and with different options. The test unit I received is rated at 100 watts and has a switchable impedance selector for 4 or 8 ohm loads. It is also equipped with a treble boost switch on the rear, which helps bring back some of the high frequencies that can be lost as you move toward high levels of attenuation. A single rotary dial on the front controls the attenuation level that can turn a full-bore cranked 100 watt amplifier down to the level of a whisper.

Our test MASS unit also included a line out (DI) connection with front panel controls for bass, mids, treble, and volume. This added control is very useful for those interested in running simple direct out signals or for those that may want to employ the "wet-dry" approach where the effects in the chain run off of the direct out into another amplifier while the initial amplifier’s signal runs dry signal to another cabinet.

Physically, the MASS is solidly constructed and heavy, due in part mostly to the internal speaker motor installed inside. Why is there a speaker inside the MASS you may ask? For tube amplifiers to function properly without stressing the output transformer, they need a speaker or some kind of "load" connected to them at all times. Many other attenuator designs employ high-powered resistors (resistive loads) which can effectively "fool" the transformer into acting like a speaker load, while some units such as the THD Hot Plate use a coil inside which acts more reactively, similar to how an actual speaker would. The MASS however is the only unit on the market to use an actual speaker motor that has physical movement (but no sound) as its own reactive load. Weber states that the sonic benefit of using a speaker motor inside is that all the complexities and variations in frequency response and impedance can occur and be translated to the final source so the tone and response of the attenuated signal remains true.

I tested the MASS with a 1972 Marshall 100 watt Super Lead as well a 1972 Hiwatt DR103 Custom 100 watt head. I used two cabinets as my test dummies to gauge the different responses in tone that I’d hear. The first cab was a ’71 Marshall basketweave cab loaded with original 25 watt "greenback" speakers, famous for their smooth crunch and distinctive tone that doesn’t tear your ear off with excessive highs. The second cab was a later Marshall equipped with 65 watt Celestions that represents more of the tone found in standard Celestions speakers made today – lots of high-end in the tone, more overall efficiency and of course a higher power-handling rating.

Playing first through the Marshall Super Lead and Greenback cabinet, the resulting tone was fairly transparent, though it became a bit darker as the more "extreme" levels of attenuation were dialed in. The treble boost switch on the back was very useful when used at these extreme attenuation settings and brought back much of the sparkle in the tone. If attenuating to the most minimal settings however, the treble boost switch could be a bit overpowering in its effect.

Now I must add that I’m not a fan of using a 100 watt amplifier at bedroom-level attenuation as a practice because it personally seems like a waste of an amp’s power tubes! Also, to fully harness the tone of these amps, I believe that the speakers should be running at least at a moderate level. But I know it’s fun to run lots of attenuation some times and it also does put the transparency ability of an attenuator to the ultimate test. All said, I feel the best use of any attenuator is to simply use it as a tool to curb some of the volume as needed when played in context with a band. Of course we all know that it is often the drummer that sets the overall volume level we guitarists play at and it takes a pounding hard drummer to balance in with a 100 watt Marshall, or especially a Hiwatt, running at full tilt. This makes an attenuator pretty much a necessity today, especially when playing out at clubs that won’t tolerate the highest volume levels.

Using either the Marshall or Hiwatt with the MASS into my 65 watt Celestion cab seemed to reveal a bit more transparency of tone to my ears than compared with the 25 watt-greenback loaded cab. The treble boost had less effect with this configuration, perhaps because the speakers are fairly bright as-is. This is why I personally stick with my old greenback cabs these days, but for the sake of testing, it was appropriate to also use a more contemporary and common speaker design.

The DI (line out) feature and associated controls turned out to be very useful, however I ran into the same exact same problem that I encountered when I had previously tested the THD Hot Plate. In some situations, to avoid a ground loop (or plainly put, a really bad, fizzy tone), you may have to "lift" the ground off of one end of the cable that hooks between the DI and the device it’s being connected to. I had to do this as well to alleviate the problem, but after doing so, I found that the tone network was nicely tuned. For those interested in the Van Halen type load setup (see the Edward Van Halen Artist Profile story for details), the MASS offers a lot of flexibility.

Now the question is undoubtedly going to come up later if I don’t address it here first – quite simply, "How does the Weber MASS’ tone compare to the THD Hot Plate?"

I did some A/B tests using all amps and cab types and found that when set for little to moderate attenuation (-8 dB max on the Hot Plate and tuned to a similar output level with the MASS), the tone of both units was very similar, though the Hot Plate was a hair brighter (which could be viewed as a benefit or a disadvantage depending on your perspective!). When going to –12 dB or more on the Hot Plate, the Hot Plate won out on versatility because that’s when its frequency compensation switches really assisted in making the tone seem more natural with extra low and high end reinforcement. The MASS’ treble boost switch serves it well at those settings as well, but overall it is more of an extreme adjustment, whereas the Hot Plate tone network is a bit more subtle and therefore more useful in a wider range of applications.

Sonically for my personal uses, which involve attenuation typically no more than –8 dB, I would be happy with either unit. Any further than that in attenuation and the Hot Plate is my favored choice simply due to the frequency compensation switches which I feel are very well tuned.

Now for direct out use or in a "wet-dry" combined setup, the versatility of having the tone network on the MASS to compensate and correct the tone of the DI signal makes it an easy pick as the winner over the Hot Plate. Direct out signals from amplifiers can typically sound atrocious in general, so being able to e.q. and set the level for them prior to going out to another amplifier, mixer, or effects, is a tremendous benefit.

All together the Weber MASS is an excellent unit and is also a tremendous value for those looking for a quality attenuator today. I label it as a "tremendous value" because there are various models available for different power handling characteristics and you can order the options you’d like as needed. Ours was a nearly fully-equipped model and at a price of 180.00, still makes it a very compelling buy.

The THD Hot Plate had previously earned a score of 10 out of 10 when I tested it last year as it ran circles around it’s well-known competitor, the Marshall Power Brake. The Weber MASS definitely does the same and you could do no wrong with it as well. With its features, solid build quality, and overall value, I’m also awarding the Weber MASS a score of 10. For more information about the Weber MASS, visit

One thought on “Weber MASS Attenuator

  1. This attenuator gave me very bad gas. All night it was just fart, fart, fart. NO idea why. Then I suddenly had the urge to bang my sister’s cat… Now THAT was actually pretty cool. I attenuated the cat’s voice, and I went to town… Excellent pussy….CAT!

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