Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: hesamadman on February 09, 2016, 02:17:02 pm
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I'm checking out this Mesa Lonestar and noticed the "thick" and "thicker" switch. After checking The schematic ( http://el34world.com/charts/Schematics/files/mesa_boogie/boogie_lonestar.pdf (http://el34world.com/charts/Schematics/files/mesa_boogie/boogie_lonestar.pdf)) I noticed it is just a bypass on the tone stack. Utilizing a 10M!!!! Resistor and a 500p cap in series. I tried this on an amp and noticed zero difference. My tone stack is a 2204 stack so it has a 100k drop down resistor. The Lonestar does not have a drop down. I'm assuming the differences of tone stack would be the reason this isn't working but does anyone have any suggestions?
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I'm pretty sure you wired it wrong. Look closely. When you select thick or thicker, the 10M resistor is shorted out, just leaving the 250pF or 500pF cap. All those 10M resistors do is prevent the switch from popping.
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Ok so the only thing that bypasses the tone stack would be the 500 and 250 (depending on how the switch is flipped) to me that just looks like a high pass filter. Is it not?
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My tone stack is a 2204 stack so it has a 100k drop down resistor.
Drop down R = slope R.
Ok so the only thing that bypasses the tone stack would be the 500 and 250 (depending on how the switch is flipped) to me that just looks like a high pass filter. Is it not?
Yes.
Treble cap has 3 options,
1. 250pF
2. 250pF || 250pF = 500pF
3. 250pF || 500pF = 750pF
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The reason i was looking into this amp is someone was dropping one off for me to lean up and change the tubes. I was confused because the bypass of the tone stack of these values, i would assume would be extremely subtle. Well i tried this mod before I even had the lonestar here. Now that I have the lonestar and have tried this option on the amp IT IS very subtle. I played around with some different values to see what I could get.
Do you think maybe they stayed at such a low value due to the fact that the tone stack is useless after a certain point? I have a .01 on my 2204 and it leaves the tone stack useless. I have it switched so I can hear the differences. I even tried a .68
I guess the way the lone star is, it seems pointless. I really dont hear enough of a difference to even make this an option on an amp.