Audio power distribution box

[AllenB]

Sure, I can see what you meant. I think one way will show a rising impedance with level and the other, falling.

 

[bentoronto]

I'm talking tube amp transformer output so it needs some minimum value of resistance as load.

I'm confused. I thought you wanted distortion and now you are saying you want to set up the amp so it doesn't distort. Should the musician have a choice out of a whole bunch of different kinds distortions to choose from?

Never thought I'd ever see a DIYaudio discussion of trafficking in distortions.

B.

 

[weltersys]

"was sent at various levels from 1 to 8 watts (a 9 dB range) to an Epiphone 8” speaker, standard issue in the Valve Jr. combo “5 watt” amp."

What was the wattage of that speaker? Our speakers are 75W (stonehenge), 150W (tonkers) etc

Most of the stock 8” guitar speakers are in the 15-25 watt range.

The Eminence 12” Tonker is nominally 8 ohms and has a 1 watt one meter sensitivity of 101.5 dB, so at just 2.83 volts, nominally 1 watt, it is already pretty loud. The Tonker has a low .8 mm Xmax, , so will distort without much drive level, but rated at “150 watts EIA426”, can withstand around 34.6 volts, though the impedance is much higher through the low and high range, so won’t actually see 150 watts when presented with 34.6 volts. The Stonehenge has slightly higher sensitivity, but less power handling.

The Epiphone 8” is probably also made by Eminence, may be similar to the Patriot 820H, a four ohm 8” with 1.59 mm Xmax, rated for 20 watts, 96.1 dB sensitivity at 2 volts.

Understanding Loudspeaker Data | Eminence Speaker

The Patriot 6” 620 (also 20 watts) at 94.6 dB sensitivity has only .4mm Xmax, so should distort at a SPL about 6 dB lower (1/4 the power) than the 820H, actually 7.5 dB lower when sensitivity is considered. The Fender 8” I tested may also have only around .4mm Xmax, considering how much more distortion it produces than the Epiphone.

The 620 may have a similar distortion profile to the Tonker while playing 13 dB less loud, like reducing 65 watts to .5 watts without using any load resistors.

Without actually testing the guitar speakers, hard to determine whether their distortion profile matches the preference of a guitar player. Fortunately, little guitar speakers can be had for the price of a couple sets of strings, find the flavor you like!

And to answer Ben's question:
"Should the musician have a choice out of a whole bunch of different kinds distortions to choose from?"
Yes!