MASS 200 (200w Attenuator)

Designed for use with 100w amplifiers and lower.


Headphone Output

Headphone Output

Footswitch Bypass * 

Footswitch Bypass

Attenuator FAQ * 

Attenuator FAQ

Cables * 


This attenuator has two knobs for tonal control. The main volume is controlled by the large Speaker knob. Then to control the treble, use the Treble Compensation knob. The treble control is always dependent on the main volume control. Be aware that the higher the setting on the main knob, the less the effect of the treble compensation. For instance, if you turn the main knob all the way to 10, you’ll notice very little change in the tone as you turn the treble compensation from one end to the other. The line out signal is dependent on your amplifier settings.

200 watt MASS with a moving voice coil speaker motor for the load. This unit is impedance swamped to protect the output of your tube amp, and may be used with 4, 8, and 16 ohm amps. Includes adjustable Line Out, System Bypass, and Variable Treble Compensation. Volume level is continuously variable to over 50db of attenuation.

Like all Weber attenuators, setting the speaker control to minimum (maximum attenuation), allows the MASS 200 to be used as a dummy load for testing or for DI use.

Optional wings may be employed for rackmounting the MASS 200. Attach these wings to the sides of your attenuator, and you can mount it in a standard 19″ rack. Uses three rack spaces. Must place the attenuator on the topmost spaces of the rack to allow proper ventilation.

There is an option to add a headphone output, and this adds an extra jack with an independent volume control. For the footswitch option, we install a relay which requires 7.5V external power. This only powers the relay – the attenuator itself is still passive. We include the power plug but the footswitch itself is not included. You can use any latching footswitch, including one incorporated in a multi-effect floor unit.

This item is hand-built to order, to ensure the best attention to detail is paid to its construction.  We build them one at a time, on a table – not hundreds at a time on an assembly line.  This allows us to reduce the margin for error and produce an overall higher-quality product.  Please allow at least 7-10 business days for your order to be built and then shipped.

IMPORTANT NOTE ABOUT HIGH GAIN AMPS*: *if you have a Fender or similar amp, and play with cleaner tones, this part does not apply to you. High gain amps such as Marshall or clones (with heavy distortion) are hard on attenuators. Unfortunately, an amp’s volume dial is not a good indicator of how much power is being produced.  Many amps can reach full power at 3 or 4 on the volume dial, so it is a good suggestion to get an attenuator with 4x the power handling. For example, if you have a 50w high gain amp, you should opt for the MASS 200. If you have a 100w amp, you should still go with the MASS 200 but you should not crank the amp. 

1) do not attenuate too far down. this puts a lot of power through a very small section of the volume rheostat which can cause it to fail

2) also do not turn your amp all the way up.  even if you’re just knocking a little off the top with the attenuator, it’s a good idea to keep the amp somewhere in the middle at most.  it’s best to find the lowest volume on the amp that is the acceptable tone to you, and then use the attenuator to bring it the rest of the way.

CABLES: for combo amps, most people like to set the unit on top of the amp. sometimes there is enough slack in the speaker wire to reach and sometimes there isn’t. these cables will make it work for you: GMC2P and GMC2E If the speaker is hardwired, then you need the PV30MH.  (click the links to view them, and add to your order if you need them.)













More often than not, your amp’s output is more than your ears can handle.  To maintain the tone of a cranked amp with saturated tubes and output transformers, a device called an attenuator is placed between the output of your amp and the speaker.  Weber offers a variety of attenuators for different applications.

Please read and consider the following prior to ordering an attenuator:

(The following text is reprinted with permission from Eurotubes.)

Here are some facts to consider when using an attenuator. Attenuators do work. They are not the cause of transformer failures. An attenuator can only simulate two out of the four components that are involved when you crank up an amp. The four components are #1 preamp tube distortion, #2 power tube distortion, #3 speaker distortion and #4 the physical movement of air that your speakers produce at high volumes. So the two components missing are speaker distortion and the physical movement of air and these are huge components! So if you’re playing at moderate volumes and just want to tame the amp down to get a bit of power tube breakup then an attenuator is a great tool, but do not expect to be able to dime your amp and then use any attenuator on the market to get the exact same sound from your amp at whisper quiet volumes. You can’t get there from here. You would be better off with a one watt amp.

So, now some answers. Catastrophic power tube failure will cause transformer and screen grid resistor failures. The reason you will read and hear horror stories from un-knowledgeable attenuator users is because they do not understand how attenuators work and the stress they put on your tubes. If in fact, a player chooses to run his amp cranked all the way on and attenuate the volume down to a whisper, then in most cases power tubes will only go a few months. Power tubes will die in one of two ways. The first and most pleasant is by simply fading and dying. The second and more popular way is to go out in a blaze of glory which is what I referred to above as a catastrophic failure which can and most often will, take out screen grid resistors.

Tubes sound great when they are really working hard but the harder you work them the faster they wear out. If you understand this and either use the attenuator sparingly or change your tubes regularly then your amp will not suffer damage.

If you are going to dime your amp out and attenuate it down to very quiet volumes then we recommend using an attenuator that is rated for twice the power of your amp’s rated output.

If you are simply going to dial an amp up to where it starts to breakup in the clean channel and then knock it down a few dB so the club owner and the sound man are happy, then using a 50 watt attenuator for a 50 watt amp will be ok.


A note about the power level: You should select an attenuator that can handle at least as much power as your amp puts out.* (see FAQ)

Amplifiers are generally designed to operate clean, and most manufacturers specify the output power as clean power. When you run the amp full blast, the output devices actually become more efficient because distortion is not considered. Under those conditions, the amp may be capable of putting out as much as 50% more power than its rated clean power. Be aware of that when choosing an attenuator, because the idea of using an attenuator is to run the amp full blast into power tube distortion and then controlling the level going to the speaker. If you are going to dime a 50 watt amp, you should choose a 100 watt attenuator.

Understanding Attenuators
An article by Michael Farnsworth
This is a wonderful article written by one of our customers, which explains attenuators in even more depth.




6 reviews for MASS 200 (200w Attenuator)

  1. Sebastian

    I got the 200w attenuator for my old 200w HIWATT Amp.
    Cause it is far too powerful, i coudn`t get near the Sound, it was invented for.
    This little black Box is exactly what i needed, to get a great volumed 70s Sound. No effects, just the pure clean sound of the Amp.
    It took a while to get it through the Customs ( Germany) Let them tape the reciept outside of the Package.
    Thanks, I love it.

  2. Nick Fainbarg

    On my mission to achieve proper high GAIN, Saturation and variable Resistance with Simulated Cab via Fractal Audio’s Cab Sim Functionality I reached out to CJ to ask about the Genius moving voice coil load design….It works and I’m stoked. The power amp is responding as if it were connected to a cab.

  3. Iron (verified owner)

    Absolutely awesome device. Johan Segeborn has a vid on youtube about bedroom volume being good enough, and he used a mass 150 to take it down to almost silent, and the results there are an excellent representation of the tone I’m getting with my mass 200. I lose no tone whatsoever until I am very quiet, and at that point it’s just some sustain that’s missing. But hey, at that point I’m using a cranked 100w marshall at tv volume… haha. At band volume (even a quiet band) it is 100% transparent. Time to crank it up, folks.

  4. Tyler

    I’ve been using this on a daily basis for years, in order to get a line level signal from my 100W Laney GH100S head for recording and rehearsing. No issues with the unit, or with my amp. Pair this with a decent cab sim, and you’ve got a nice silent setup.

  5. Matt McCool (verified owner)

    These attenuators are serving me well. I think that if anything, I will use them to take the last 1 to 4 dB off the top if the sound is too loud for the room. Mostly I will not use these unless I have to.

    I had an uh-oh moment when the shipping company sent me damaged gear. I didn’t notice that an input channel on my cabinet was an open circuit because I was connected in stereo. If I didn’t notice that 2 of these speakers were silent and I brought this on stage with a false pass with equipment testing, I could’ve damaged the amp and blown the speakers. Using these attenuators prevented any risk of damage with the way I configured it. Luckily I solved the problem before it came to that and I am thankful that these devices acted as a failsafe.

    What I found out in this experience is that this manufacturer was very supportive and helpful when I needed it. I am happy and impressed with both the customer service and the device.

  6. dberto@comcast.net (verified owner)

    Purchased my Mass200 to tame down a few amps for home use (and some minor dates I will still play occasionally) . Specifically an SV20H, JCM800, and a few others. It works EXACTLY as I had hoped. I am not necessarily running the amps at whisper volume but to a tolerable home loudness. I do not detect any “tone suck” of any sort. Just getting my cranked amps a bit more under control with the same cranked tones as I get with the amps running wild. The treble compensation works great also, although I have used it more to darken up one amp in particular I always thought was a big bright. I think it was a great purchase and a fantastic product.

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