Better attenuator than Hotplates?

[What?]

Just a word on Weber Mass attenuators, and using them at low volume.

First, we have to acknowledge that this a very popular, well built, good value, well liked product and if it works good then it is good. But, its not perfect in every case and there are a couple of reasons for this for where this happens.

The main one is that the way it dials down to low volume is by using a high-power pot in an L-pad arrangement. As you get low, this starts to present a very low impedance to the speaker, which damps its response, preventing it from developing a natural rise in treble due to its inductance, giving a dull sound, and also reducing the speakers bass resonance. You'll notice this the greatest on amps with less or no negative feedback, for which this effect is a dominant part of their tone, but it will happen to some extent with nearly all tube guitar amps.

Also, they are presented with options for using 16, 8 or 4 ohm amp taps. On all the schematics Ive seen, the basic circuit is based on 16 Ohms, and this is what the internal speaker motor uses. The 8 and 4 options are produced by putting fixed resistors in parallel with the front end. This reduces its action as a reactive attenuator, so with 8 ohm input, it is 50% resistive and at 4 ohm its 75% resistive.

Workarounds: If possible, id suggest to try to work with 16 Ohms on these units. If you need 8 Ohms, Id build in another coil/resistor arrangement at the front to keep the balance

And, (I don't have one and haven't tried this), if playing at low volume, add about a 10 Ohm resistor in series with the speaker, to help with the first issue. at low volume, the amp wont see much difference, but the speaker will respond more naturally

(Or, build a better design for less $!)

What you describe here is bang on to my experience with the Weber Mass 200. I have used mine with a DSL50 (green channel cranked) and a Ceriatone Plexi 51, 8 ohm and 16 ohm cabs. I have had a better result with the 16 ohm cab and at lesser attenuation (higher volume). As attenuation is increased (lower volume) toward bedroom level, the sound does get progressively more dulled in the highs and with less lows. I have been using mine for a while now mostly with the Plexi 51 in combination with the amp's PPIMV.

And I'm getting reminded here that I still need to build at least one (likely 2) of the diy attenuators.

 

[malice95]

I've used the Weber Mass 200 and the 50. Both are great attenuators, but ultimately I ended up with a Fryette PS2. I notice really no loss of tone from the PS2 until I get down to volumes my 4x12 cant handle. At some point you aren't moving the speaker enough to reproduce the sound fully. For times when I need silent playing I turn on a Cab M+ with the PS2 on zero volume. That gives me really great tone using decent Celestion IR's.