Last night I did that gig with my Hot Rod Deluxe (40 watts, 6L6s) through the Mini Mass 50 watter, and all went well. No smoke or smells, and fabulous tone! The HRD was up about 90% through the clean channel for four sets. Man, that's a whole 'nother world! Rich tone and lots of dynamics. Love it.
And I guess the "twice the wattage" advice is more precautionary than absolutely necessary. Great to know.
Just want to drop a line to say how impressed Iíve been by my Mini Mass. Not only does it now take the volume down to zero but even at high levels of attenuation there is none of that loss of tone which one would usually expect, in fact on my Epiphone BC30 the slight loss in high frequencies actually tames the slight ice pickiness inherent in the amp. -- Ian Wigg
25 and 50 watt MiniMASS. 4, 8, 16 ohms, treble compensation, MASS bypass, line out. The MiniMASS employs an actual speaker
motor for realistic interaction between the attenuator and the output circuit of the amplifier. The attenuation is continuously
adjustable from about -6dB to over -50dB. By turning the speaker control to minimum (maximum attenuation), the unit may be used
as a dummy load for testing or for DI use.
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.