Low Pass Filters at the end of Dirt boxes.

[Bill Mountain]

When designing low pass filters at the end of a dirt box how much thought do you give to the speaker's natural high frequency roll off?

Personally I like to let the speakers take off most of the high end but that of course causes trouble when going direct.

What about you guys?  Do you use speaker sims?  Do you just use you tone control (on your pedal or amp)?

I don't have a problem.  I'm just wondering how everyone else does it.

[Mark Hammer]

Big sluggish 12" speaker cones DO remove a lot of highs....from an otherwise naked guitar signal. 

A dirt box adds more harmonic content, so the goal is often to use lowpass filtering to restore tonal balance.  Personally, I want a dirt box to provide a different "character" to my tone, but I want the resulting sound to be roughly what I set the tone controls to on the amp.  What I make the filtering on the pedal do is give me a different character when I stomp on the switch, but the same bandwidth.  No dirt box should send the user scrambling back to the amp or to the guitar controls to turn the treble down.

[WGTP]

Those low pass filters at the end frequently are there to remove FIZZ sometimes.  Increased harmonics add treble. 

The dual resistor cap circuits that have become popular are reputed to roll off at 12db/oct., however simulations in LTSpice and others indicate that the caps and resistors "sum" into a single 6db/oct. filter.  I haven't measured it to be sure.

Many times 12" speakers have a large peak in their response around 3.5kHz that may or may not enhance the tone. 

Sitting to the side of the cabinet should also be considered.  Age has added a natural roll off of the highs. 

[aron]

I just tune to my system and ignore any other scenarios! :-)

[Keppy]

I'm with Mark. I set my tone controls so I have similar amounts of treble with the effect on or off. I've seen too many guitar players whose performances suffered due to the ice-pick-to-the-forehead treble boost of one effect or another. They start off sounding awesome, then they step on a switch and send you running to the back of the room holding your ears.