12AY7 plate current

workingonit · 23rd April 2010, 04:49 PM

I have a 12AY7 preamp project and, in reference to the plate characteristics chart, I can achieve a preferred operating point over a range of plate currents. Are there any advantages to running the tube at a higher current; that is, would you purposely run a higher current draw than you need?

bob91343 · 23rd April 2010, 05:40 PM

Higher current can create more noise. And drive requirements may increase. I don't see any advantage. Why are you using that tube? The 12AX7 is usually the preferred type, or one of its fancy numbered equivalents, like 7025 and the like.

Arnulf · 23rd April 2010, 06:38 PM

Tubes are usually more linear when their operating point is chosen so that Iq is higher. Refer to dynamic characteristics graph in tube's datasheet for more information,

workingonit · 23rd April 2010, 07:27 PM

Quote:

Originally Posted by bob91343

Higher current can create more noise. And drive requirements may increase. I don't see any advantage. Why are you using that tube? The 12AX7 is usually the preferred type, or one of its fancy numbered equivalents, like 7025 and the like.

12AY7s have a broader bias range compared to the AX7 at the same B+. In this app I ran out of input headroom with the AX7 and didn't need the higher gain, anyway.

23rd April 2010, 04:49 PM	#1
workingonit diyAudio Member Join Date: Dec 2005 Location: North Carolina	12AY7 plate current I have a 12AY7 preamp project and, in reference to the plate characteristics chart, I can achieve a preferred operating point over a range of plate currents. Are there any advantages to running the tube at a higher current; that is, would you purposely run a higher current draw than you need?

23rd April 2010, 06:38 PM	#3
Arnulf diyAudio Member Join Date: Feb 2009	Tubes are usually more linear when their operating point is chosen so that Iq is higher. Refer to dynamic characteristics graph in tube's datasheet for more information, __________________ mod verb, transitive /mod/ to state that one is utterly clueless about the operation of device to be "modded" and into "fixing" things that are not broken; "My new amplifier sounds great so I want to mod it."

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23rd April 2010, 05:40 PM	#2
bob91343 diyAudio Member Join Date: Mar 2010	Higher current can create more noise. And drive requirements may increase. I don't see any advantage. Why are you using that tube? The 12AX7 is usually the preferred type, or one of its fancy numbered equivalents, like 7025 and the like.

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