Dialling In The AC20

Dillonski

Dillonski

Inspired
Hey everyone,
I've been using the AC20 model a lot lately (12AX7 T), however, I'm having some difficulty controlling the high frequencies at high volumes. I've read up on the fletcher munson effect and have attempted to compensate by using the low/high cut in the drive (100hz & 6000hz) and cab block (125hz & 6000hz), as well as the amps high cut control. When I increase volume with these settings, the high end becomes unbearable, but cutting the highs anymore seems to leave me with a very dull tone. I don't know how relevant it is, but I'm using KRK Rokit 5 G3's.

Any help would be appreciated, I'll attach the preset to this.

Thanks! :D
 

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Dillonski said:
Hey everyone,
I've been using the AC20 model a lot lately (12AX7 T), however, I'm having some difficulty controlling the high frequencies at high volumes. I've read up on the fletcher munson effect and have attempted to compensate by using the low/high cut in the drive (100hz & 6000hz) and cab block (125hz & 6000hz), as well as the amps high cut control. When I increase volume with these settings, the high end becomes unbearable, but cutting the highs anymore seems to leave me with a very dull tone. I don't know how relevant it is, but I'm using KRK Rokit 5 G3's.

Any help would be appreciated, I'll attach the preset to this.

Thanks! :D
Click to expand...

Man that's strange. I find the Morgans among the easiest models to dial in. In fact, they hardly require any tweaking at all in my experience. A 6000khz lpf to me is fairly aggressive. For the Morgans, I set it at 10000khz and the chime is perfect, no harshness whatsoever. What kind of guitar are you using?
 
RKF said:
Man that's strange. I find the Morgans among the easiest models to dial in. In fact, they hardly require any tweaking at all in my experience. A 6000khz lpf to me is fairly aggressive. For the Morgans, I set it at 10000khz and the chime is perfect, no harshness whatsoever. What kind of guitar are you using?
Click to expand...

I'm using a PRS Custom 24
 
The factory cab was certainly an improvement. I'm thinking it might just be my guitar not playing well with that amp model, created a Plexi preset today which sounds great at any volume
 
Dillonski said:
The factory cab was certainly an improvement. I'm thinking it might just be my guitar not playing well with that amp model, created a Plexi preset today which sounds great at any volume
Click to expand...

Yeah, definitely don't overlook the stock cabs. I don't use them for my gainier sounds, but for cleanish models, like the Morgans, there are some real gems in there.
 
Have you looked up what the amp controls do? Check the wiki or Yek's amp posts. The amp only has one knob and it is. High cut. Between them knob and the high/low cut I don't have an unusually amount of highend
 
I also use the AC20 and the Larry Mitchell cab... The only time I found the hi-end to be a problem is when I run an overdrive in front of the amp block. I have had better luck using a scene controller to bring up the amp gain.

I am not in front of my AX8, but if people can post some presets I think it would be easier to see how you are getting the tones.
 
still my favorite amp in there. can't say I have this issue either and my ears are kind of sensitive to really high frequencies. I guess make sure you don't have something crazy going on in your global eq or another eq in your preset. a real morgan has no eq knobs other than a high cut and I only adjust that knob and the gain knob. I also have been experimenting with input trim at about half. I have found a great clean sound that way. I haven't even been using any eq on my patches other than the tone knob on the drive pedal I'm using with it. never had a real one or even used one but I would love to see how it compares cause I love the model.
 
WayneII said:
That cab may be the culprit. I use the stock cab. Can you re-download the cab and see if that makes a difference? Try it with the factory cab and see what kind of results you get why you are at it.
Click to expand...

I used the LM cab this Friday for a church concert and the Morgan choked up. The tone became harsh and the sustain was killed. Not sure what really happened. Will revert to the factory cab and see if it happens again.
 
Don't give up until you've tried the tone knob on your guitar. It can work wonders to dull the ice pick and still leave sweetness behind.
 
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So used the LM cab and the default cabs for another concert. I got glorious tone from F119 cab.
Haven't found anything better.
Anyone tried the bipolar pack from York studio with DC30/Morgan amp?
 
FWIW: In the past I've run into that highs that can't be properly tamed problem with some real EL84 amps: With some speaker cabinets (or IRs in modeling) there is overt high frequency resonance regardless of what is done with the usual tone controls: Try Different IRs, maybe adjusting the resonance peak frequency on the amp speaker page. With EL84 amps in general - getting the right treble (preamp) and high cut (power amp) settings will be important to getting the high end right with the particular pickups in use: sometimes turning the treble up and also rolling it off with aggressive high cut is what works. Keep at it; you'll get it to sing, and it will be awesome.
 
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I always find the AC20 to be a bit bright for me. I do like to come back to it from time to time. Give the DIV/13 FT37 HI
a try. It is beefy but still has great high end clarity.
 
Rex said:
Don't give up until you've tried the tone knob on your guitar. It can work wonders to dull the ice pick and still leave sweetness behind.
Click to expand...
This. And also from the pedals. Don't be afraid to turn the tone knob all the way down. Many pro's do this. Don't forget to use your ears.

Image below from Gary Clark's rig. Zendrive has it's tone down to 0. Tone also lowered from the MXR.
GCJ_Pedalboard.jpg
 
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