EL34 SE in 430V?

zxx123 · 29th November 2005, 06:14 AM

I've found an old stereo amp, which
works with a pair of EL34s.

The B+ of EL34's plate is measured 430V.
Wow, I have never seen before. The working data in Duncan's
only show SE in low voltage, SE triad in HV, or PP in HV.

No, the amp is not triad-connected.
Can you guess its real power rate? (8 ohm)

Original Burnedfingers · 29th November 2005, 10:34 AM

Care to share a schematic of the amplifier?

zxx123 · 29th November 2005, 11:29 AM

Unfortunately, I don't have it.

alejo · 29th November 2005, 11:45 AM

Cathode resistor value?

Valve rectifier type?

You measured with valves in your socket or without them?

zxx123 · 29th November 2005, 02:38 PM

470ohm is used.
30V is measured.

Thanks.

kevinkr · 29th November 2005, 08:36 PM

You mean not triode connected?

What type of rectifier is used?
Is the screen connected to a tap on the output transformer, i.e. ultra-linear operation or is it pentode connected? (Screen to somewhere in the power supply?)

Idle current is about 64mA and the effective plate voltage is 400V (plate to cathode.) Plate dissipation is right around 25W or about the tube's maximum dissipation rating.

Output power might be as high as 10Wrms..

Kevin

Tom Bavis · 29th November 2005, 08:55 PM

They're pushing those tubes... 25 Watts total plate/screen dissipation. This may not be as linear an operating point as at a lower voltage, but it probably gives more power, and feedback was probably used to lower distortion.

29th November 2005, 06:14 AM	#1
zxx123 diyAudio Member Join Date: Aug 2003 Location: ca	EL34 SE in 430V? I've found an old stereo amp, which works with a pair of EL34s. The B+ of EL34's plate is measured 430V. Wow, I have never seen before. The working data in Duncan's only show SE in low voltage, SE triad in HV, or PP in HV. No, the amp is not triad-connected. Can you guess its real power rate? (8 ohm)

29th November 2005, 11:29 AM	#3
zxx123 diyAudio Member Join Date: Aug 2003 Location: ca	.... Unfortunately, I don't have it.

29th November 2005, 02:38 PM	#5
zxx123 diyAudio Member Join Date: Aug 2003 Location: ca	values are 470ohm is used. 30V is measured. Thanks.

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29th November 2005, 10:34 AM	#2
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Care to share a schematic of the amplifier?

29th November 2005, 11:45 AM	#4
alejo diyAudio Member Join Date: Jun 2004 Location: bs.as.	Cathode resistor value? Valve rectifier type? You measured with valves in your socket or without them?

29th November 2005, 08:36 PM	#6
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	You mean not triode connected? What type of rectifier is used? Is the screen connected to a tap on the output transformer, i.e. ultra-linear operation or is it pentode connected? (Screen to somewhere in the power supply?) Idle current is about 64mA and the effective plate voltage is 400V (plate to cathode.) Plate dissipation is right around 25W or about the tube's maximum dissipation rating. Output power might be as high as 10Wrms.. Kevin

29th November 2005, 08:55 PM	#7
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	They're pushing those tubes... 25 Watts total plate/screen dissipation. This may not be as linear an operating point as at a lower voltage, but it probably gives more power, and feedback was probably used to lower distortion.

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