Amp "bright" parameter

edo

edo

Power User
Vendor
I generally mess around with presets with the axe edit, today I didn't have the computer with me and on the axe fx amp page I discovered a bright knob (I'm on 16.4). When was it introduced? How does it work? I'm in the middle of a tour and was actually looking to get some more sparkle out of my dual ac30's preset.. What's the difference between turning up the treble and turning up the bright parameter? If I were at home I'd just experiment myself, but being in different venues with different PA's, different wedges etc, I'd like to know the difference in theory before I make adjustments.
 
from wiki:

BRT (Bright) switch

Located under the Treble knob.
The bright cap in real amps is used to compensate for guitars with weak pickup loads. Treble increases as gain is decreased. It changes the mids which affects gain too.
Cliff: "The Bright switch always controls the bright cap on the input volume". Source
Turning up the amp's Drive or Master may decrease the impact of the Bright switch, depending on the amp type.
It's possible to change the effect of the Bright switch on the tone. In the Advanced parameters adjust the Bright Cap value.
Some amp types, such as Plexi, the Bright switch is set at a very high value. It has a large impact on the amount of gain.
Cliff: "If an amp doesn't have a bright switch, the operation of of the models' bright switch is undefined. I chose what I considered a reasonable value for the bright cap but if that doesn't satisfy the user then they are free to change it to a different value." Source
Note: this is not to be confused with the BRIGHT shelving filter control between the preamp and power amp (see below).
 
I think he was asking about the Bright knob, not the switch...

Firmware 13.06: Added “Bright” control to Amp block. This high treble control is a shelving filter between the preamp and power amp and may be used to darken or brighten the output of the preamp. This control also accurately replicates the “Presence” control found in the Mesa Triaxis preamp when set to negative values (the Presence control in the Triaxis is actually a high frequency cut shelving filter). Note: this is not to be confused with the “Bright Switch” which engages/disengages a capacitor across the drive pot.
 
Thanks. I must have missed that firmware.. So, if I wanted to brighten up the ac30 model I'd rather turn up treble and turn down cut, right?
 
I use the bright knob all the time, but then I always did like a bright guitar sound. To me it just sounds a bit more open and natural than just "turning up the treble". I kinda wish I could have a bit of "bright" as default on all amps, but that's just me.

And yes, my hearing is fine, or was last time I checked. At least up to around 17khz...
 
Up to fw 14 I had to turn down the treble and cut higher frequencies in the cab block because strats sounded harsh, now it's the other way around, I removed cab block hi cut, turned up the treble and lowered the cut, and still, it's not bright enough.. I guess I'll have to experiment with fw 17 when I get back from the tour
 
it may not be the right way to do things, but i always try basic controls to get as close to what i'm hearing in my head then experiment with deep controls.
 
I use the bright knob to compensate for the fact that I turn off the bright switch on most models. I find that the switch creates a fizzy overtone when notes are cut short, and using the knob instead gets the high end back to a similar place without that.
 
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