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Re: 6EJ7 cascode A [message #30491 is a reply to message #30476]

Sat, 12 February 2005 14:27

Damir
Messages: 1005
Registered: May 2009

Illuminati (2nd Degree)

You probably know this, but just in case... Amplification of the cascode is A=gm*Ra, just like in pentode, where gm is gm of "compound device, quasy pentode", or A~gm1*Ra , where gm1 is transconductance of the lower triode, IME - always gives a little "optimistic" values. With unbypassed Rk, gm1`~gm/3, and with Ra~8k2 - A~40.
Of course, there are "full" formulas for this ("Valve Amplifiers", RDH, "Vacuum tube amplifiers"). For complicated cascode versions there`s always SPICE (hey, I have EF184 pentode 3f4 model - if you feel desire for it...).
I also thought about cascode RIAA, but that Rout...

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[Message index]

		RIAA preamp? By: Damir on Thu, 03 February 2005 11:39
		Re: RIAA preamp? By: Manualblock on Thu, 03 February 2005 13:12
		Re: RIAA preamp? By: Damir on Thu, 03 February 2005 14:46
		Re: RIAA preamp? By: Manualblock on Thu, 03 February 2005 15:18
		Re: RIAA preamp? By: PakProtector on Fri, 11 February 2005 08:05
		Re: RIAA preamp? By: Damir on Fri, 11 February 2005 14:24
		something like it.... By: PakProtector on Fri, 11 February 2005 15:27
		6EJ7 By: PakProtector on Fri, 11 February 2005 18:28
		Re: 6EJ7/EF184 By: Damir on Sat, 12 February 2005 06:37
		Re: 6EJ7/EF184 By: PakProtector on Sun, 13 February 2005 19:33
		Re: 6EJ7 cascode A By: Damir on Sat, 12 February 2005 14:27

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