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07-18-2020, 06:37 PM
Hi Guys
The Bassmaster only has two gain stages in its preamp and provides a very clean tone. One way to get compression from the preamp is to simply reduce its voltage bt increasing the dropping resistor from the screen node of the supply.
Another way to achieve natural compression is to make the preamp three stages or even four stages. Yes, any of these methods might run into overdrive tones but that is easily controlled. The extra stages add veils of tube character - harmonic build-up - that will fatten the sound and make it a bit rounder as if it were deliberately compressed.
Having compression specifically, as on a dial say, the circuit from TUT2 Fig.6-54 will possibly work for you - depends exactly what you are after.
The general approach can be wrapped around the power amp and linked back to the output tube grids, further to the splitter, or to the splitter input using a jfet or LDR. Some of these methods are shown in TUT4 Figs. 4-28, 4-35, 4-38**, TUT6 &-16, 7-17. Note that ** works on the output stage as a variable current limit and is therefore dependent on how hard the output is driven. This can be made to track Power Scale settings if needed.
The Bassmaster only has two gain stages in its preamp and provides a very clean tone. One way to get compression from the preamp is to simply reduce its voltage bt increasing the dropping resistor from the screen node of the supply.
Another way to achieve natural compression is to make the preamp three stages or even four stages. Yes, any of these methods might run into overdrive tones but that is easily controlled. The extra stages add veils of tube character - harmonic build-up - that will fatten the sound and make it a bit rounder as if it were deliberately compressed.
Having compression specifically, as on a dial say, the circuit from TUT2 Fig.6-54 will possibly work for you - depends exactly what you are after.
The general approach can be wrapped around the power amp and linked back to the output tube grids, further to the splitter, or to the splitter input using a jfet or LDR. Some of these methods are shown in TUT4 Figs. 4-28, 4-35, 4-38**, TUT6 &-16, 7-17. Note that ** works on the output stage as a variable current limit and is therefore dependent on how hard the output is driven. This can be made to track Power Scale settings if needed.
