MASS™
Mobility Analog System Simulator

Click the picture for a full size view
5lb   (1.36Kg)
10" (25.4cm) wide, 5" (12.7cm) deep, 3-1/2" (8.89cm) high.
MASS

25 Watt MASS
 
$175

Qty


Select Options
Add Footswitch Bypass +$25
     Line Voltage for Footswitch Power
     Add Headphone Tap +$25
Rackmount Wings -- $25/pair
Balanced Line Out (TRS) -- $15


50 Watt MASS
$205

Qty


Select Options
Add Footswitch Bypass +$25
    
Line Voltage for Footswitch Power
    

Add Headphone Tap +$25
Rackmount Wings -- $25/pair
Balanced Line Out (TRS, not XLR) -- $15


100 Watt MASS
$240

Qty


Select Options
Add Footswitch Bypass +$25
     Line Voltage for Footswitch Power
    
Add Headphone Tap +$25
Rackmount Wings -- $25/pair
Balanced Line Out (TRS, not XLR) -- $15




Instructions for Use
1. Disconnect speaker from amp
2. Connect speaker to output of MASS
3. Connect amp speaker output to input
of MASS with a short cable.
The cable must have the appropriate connectors for your amp.

Click here for a description of the MASS controls and input/output jacks.
I received the 100 Watt Attenuator you built. Great workmanship (thought it was a thing of the past) and it works flawlessly. I can turn the vibroverb to 7 and get great tone without my ears bleeding and the other features on it give me a wealth of options in creating the tone I want.

Once again, thanks for taking the time and pride in your work to do it right!

Best Regards,
Carl Campbell

25, 50 and 100 watt MASS. 2, 4, 8, 16 ohms, 0, 3db, and 6db treble boost, MASS bypass, line out, tone stack for line out, tone stack bypass, extra output jack, range switch. All controls are on the front panel. The MASS employs an actual speaker motor for the load to yield a realistic interaction between the attenuator and the output circuit of the amp. The attenuation is continuously adjustable from zero to over -70db using the speaker control and the range switch. By turning the speaker control to minimum (maximum attenuation), the unit may be used as a dummy load for testing or for DI use. Optional wings ($25) may be employed for rackmounting the MASS. The MASS occupies two rack spaces and requires adequate ventilation for proper operation.

Please read and consider the following prior to ordering an attenuator:
(The following text is reprinted with permission from Eurotubes http://www.eurotubes.com/euro-y.htm)

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 unknowledgeable 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.