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Add a subwoofer output to driver stage

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gerrittube

gerrittube

Member
Joined 2018
#1
Hi,

I'm about to add a subwoofer output to a 6SN7 driver stage (Williamson style). U1a is the amplifier; U2b is the phase inverter.
Too keep things simple I added a STP8NM60 MOSFET (or similar) as source follower. My idea is that the MOSFET will lot add a lot of load to the first triode (U1a),

According to LTSpice this seems to work OK. With only 1.1 mA and approx. 300 VDC across the MOSFET the dissipation is only 0.33 Watt.

kt150 versterker subwoofer aansluiting.png


Note: The original 100K plate resistor for U1a was split into 2 resistors of 85K and 15K. Adding C5 creates a short for AC. The reason for this change is to lower the gain without changing the DC settings.

Any additional suggestions will be welcome.

Regards, Gerrit
 
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