Series-Shunt Attenuator

[randyone]

I need to drop the sound level of my amp for home use (pesky neighbors) and I have picked up the parts for a series/shunt attenuator (ala Dr Z - AirBrake). From various pictures (2 x 100 watt 25 Ohm resistors - one fixed and one variable and a rheostat) on the web/this site I have worked up a schematic.

After looking closely at this I am now having serious concerns about changes to the output impedance of the amp when using this sort of attenuator. It looks to me that the output impedance (resistive component only) will be anywhere from 28 to 150 ohms including the speaker impedance.

My question to the forum gurus; is this a safe (to the amp) attenuation approach considering that this impedance mismatch will translate, via the OT, to a considerably lower impedance match seen by the power tubes.

Can the OT and the power tubes (EL84 or 6V6) tolerate much lower output loading without radically shortening their life expectancy?

I am a bit limited to my attenuation approach as there are no RShacks here and shipping is cost prohibitive - Indonesia.

Would switching in a B+ voltage drop accross some 50v zeners be a better approach?

Ideas?

Randy

[randyone]

my schematic is bass ackwards - reverse the input with the output and the load impedance drops to a much more acceptable 22 ohms with max atten and 16 ohm speaker load.