clarification on bold/spongy settings of 3ch dual rec

[shatteredsquare]

Hi/Low power on my old stereo 50/50 kicks it down from 50 watts per side to 15 watts per. When you hit the spongy switch on a dual rec, does it actually reduce the watts, like on the multi-watt heads, or does it do something else? I'm curious to know what exactly "spongy" does inside, and can't seem to find much about that little detail.

(When you hit spongy does it still cook all 4 tubes but just reduce the voltage overall, or does it run half power on just two tubes or something like that?)

 

[fluff191]

It reduces voltage to all 4 tubes.

 

[domct203]

Spongy reduces the voltage to the entire amp (pg. 14 of the Dual Recto manual), not just the powertubes. This changes the plate voltages and bias of every tube in the amp, pre and power.

It is actually another tap on the primary side of the power tranny. It reduces voltage by changing the ratio between the primary and secondary side of the tranny, and can be seen in the schematic (top left):

This simulates the use of a variac (varable transformer) on the main voltage input, something EVH is famous for.

Hope this helps.

Dom

 

[screamingdaisy]

What he said.

From what I've been told (never measured it myself) it drops the mains power from 120v down to 90v. This also reduces the headroom, and if I remember correctly it drops the amp from 100w down to around 70w.