Can someone explain to me the difference between pentode vs. triode, as in the Blackheart amps? Of course, one wattage level is in pentode mode and another is in triode. I don't have a clue what these terms mean?
Thanks in advance.
Can someone explain to me the difference between pentode vs. triode, as in the Blackheart amps? Of course, one wattage level is in pentode mode and another is in triode. I don't have a clue what these terms mean?
Thanks in advance.
Guitars: 2003 and 2004 American series strats, Squier Classic Vibe 50's Strat, Squier Deluxe Strat.
Amps: Line 6 Spider IV 120, Vox AD50VT 212, and Peavey Transtube Bandit 112.
Pedals: Digitech Bad Monkey.
The EL84 is normally a pentode, which means it has 5 elements inside the tube: anode, cathode, and three grids in between. Grid 2 normally has its own node on the power supply, but in triode mode, it is connected to the anode. This cuts the power, and makes the amp darker.Originally Posted by TS808
I hardly ever use the triode mode on my LG head, I just prefer the pentode tone.
tung
- Dave Lizewski, Kick-A$$I was just a regular guy. My only super power was being invisible to girls.
This is what I posted from what I found from modifing a Crate V5 that also has an EL84
Driving the EL84 with a signal generator have calculated the capacitance from plate to control grid to be approx 2.2pf in triode mode with the Miller effect this becomes approx 30pf this in parallel with the 220pf has a slight effect on the high frequency roll off of the EL84 (20KHz in pentode mode 19KHz in triode mode)
Some of the major changes between the two modes is output power 5 watts pentode mode and 1.5 watts in triode mode. Also plate impedance 38k ohms approx for the pentode mode 2k ohms in the triode mode the result the amplifier is more dampened in the triode mode closer to a solid state amplifier sound then in the pentode mode
So triode mode not only drops power it reduce overshoot due to inductance, capactance and other effects relative to the speaker used over all it won't sound as bright as the pentode mode. If you surf the web you will see tube HiFi folks like the triode mode with some amps that have 800-1000 volts on the plate and 300 dollar tubes.
In simpler term, triode is half of pentode. When you flip the switch it cuts off half of the tubes.Originally Posted by TS808
_____
GUITARS - Carvin DC127M - Carvin Bolt kit
AMPS - Bogner Alchemist 112 - Blackheart Handsome Devil half stack
FXs - Roger Linn Adrenalinn III - Boss GT-10
_____
The tone is definitely not as brilliant as in pentode mode and does of course break up earlier. I like jumping back and forth between the two though.Originally Posted by kiteman
Guitars: 2003 and 2004 American series strats, Squier Classic Vibe 50's Strat, Squier Deluxe Strat.
Amps: Line 6 Spider IV 120, Vox AD50VT 212, and Peavey Transtube Bandit 112.
Pedals: Digitech Bad Monkey.
Agreed, I use the triode mode a lot. It sound softer compared to pentode.Originally Posted by TS808
_____
GUITARS - Carvin DC127M - Carvin Bolt kit
AMPS - Bogner Alchemist 112 - Blackheart Handsome Devil half stack
FXs - Roger Linn Adrenalinn III - Boss GT-10
_____
I posted earlier what the changes were in the amplifier that I modified to have both pentode and triode mode. An analogy to what the triode vs. pentode mode is like would be dribbling a basket ball with the output transformer and speaker the ball your hand the output tube. In the pentode mode it is like bouncing a well inflated basket ball easy to bounce and will continue to bounce by it’s self for a while when you stop (the bounce being the harmonics or high frequencies you hear). While the triode mode is as if you took air out of the ball, you have to work harder to bounce the ball and it stops quickly if you stop. So in the triode mode more power is lost across the output tube with less power to the speaker and the speaker is stopped quickly by the action of the tube (lower harmonics you hear as less high frequencies).
Last edited by jim p; March 8th, 2009 at 03:45 AM.
Very nicely explained!Originally Posted by jim p
=-) PJ
Shouldn't that be semidiode or whatever the latin for 2 1/2 is.Originally Posted by kiteman
I pick a moon dog.