Humbug
Roadie
- Messages
- 132
With my previous load box circuit (BFL T652, thread here), the goal was to see how close one could get to an actual cabinet impedance. For this reason I chose to replicate the most characteristic / idiosyncratic cabinet I had access to (60's Marshall 412, Celestion T652 alnico speakers). The result was very close to the cabinet and a tremendous load, but not very versatile. It was also unnecessarily complex with too many parts. So I made a simpler one!
This one is based on a 70's Marshall 412 cab with T1220 greenbacks and is a much simpler circuit. The two rise inductors are of the same value and have no parallel capacitors. There is only one parallel resistor, to tune the slope of the rise. These are the values (The bypassed resistor drawn in series with the resonance inductor is there to "de-Q" the resonant peak if the inductor's resistance is too low):
Edit: I see now that there is an error in the schematic. R3 is 6 ohm, not 5. Both will work, though.
The L1 and L2 inductors are Dayton Audio LW14-60 (0.2 ohm), and L3 is a Dayton Audio IC185-5 (0.5 ohm).
Keen eyes will have noticed that both the resonant peak and the rise are more severe on the load than the speaker. This is to compensate for the damping effect of the enclosure I'm using, and I expect the frequency response will be bang on when I get a chance to test it (famous last words?
).
Obviously I accept no responsibility if you build this and blow up your amp and all that.
This one is based on a 70's Marshall 412 cab with T1220 greenbacks and is a much simpler circuit. The two rise inductors are of the same value and have no parallel capacitors. There is only one parallel resistor, to tune the slope of the rise. These are the values (The bypassed resistor drawn in series with the resonance inductor is there to "de-Q" the resonant peak if the inductor's resistance is too low):
Edit: I see now that there is an error in the schematic. R3 is 6 ohm, not 5. Both will work, though.
The L1 and L2 inductors are Dayton Audio LW14-60 (0.2 ohm), and L3 is a Dayton Audio IC185-5 (0.5 ohm).
Keen eyes will have noticed that both the resonant peak and the rise are more severe on the load than the speaker. This is to compensate for the damping effect of the enclosure I'm using, and I expect the frequency response will be bang on when I get a chance to test it (famous last words?
).Obviously I accept no responsibility if you build this and blow up your amp and all that.
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