JLTI Tube Preamp

JPannell · 4th July 2005, 02:16 AM

Hi guys,
I am currently constructing a preamp based somewhat on the JLTI tubed gainclone. http://www.customanalogue.com/diytub...lone/index.htm
I am building the front end of this circuit to feed my power amp. For reasons purley of aesthetics I am using one tube per channel. This will leave me with an extra triode on each channel. I have read that the triodes simply be paralelled together, and this may actually provide better performance. Is this the best way to take care of these extra triodes. I am blindly assuming that you don't want to leave the pins floating. Any help would be very appreciated, I really don't know much about tubes.
Thanks,
Jason

Sheldon · 4th July 2005, 04:15 AM

You can leave one side unused. No B+, no cathode or grid connection. Apparently the heater will run more or less forever. If you wire one channel for one section and the other channel for the opposite section, you can switch the tubes between channels after a long time and get fresh sections on each side.

Or, you can do the full Joe Rasmussen treatment and use one tube each side in this configuration:

http://www.diyaudio.com/forums/attac...amp=1105035450

I think Shoog did this one. Search and you can probably find the original thread.

Sheldon

4th July 2005, 02:16 AM	#1
JPannell diyAudio Member Join Date: Oct 2004	JLTI Tube Preamp Hi guys, I am currently constructing a preamp based somewhat on the JLTI tubed gainclone. http://www.customanalogue.com/diytub...lone/index.htm I am building the front end of this circuit to feed my power amp. For reasons purley of aesthetics I am using one tube per channel. This will leave me with an extra triode on each channel. I have read that the triodes simply be paralelled together, and this may actually provide better performance. Is this the best way to take care of these extra triodes. I am blindly assuming that you don't want to leave the pins floating. Any help would be very appreciated, I really don't know much about tubes. Thanks, Jason

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4th July 2005, 04:15 AM	#2
Sheldon diyAudio Member Join Date: Dec 2003 Location: San Diego	You can leave one side unused. No B+, no cathode or grid connection. Apparently the heater will run more or less forever. If you wire one channel for one section and the other channel for the opposite section, you can switch the tubes between channels after a long time and get fresh sections on each side. Or, you can do the full Joe Rasmussen treatment and use one tube each side in this configuration: http://www.diyaudio.com/forums/attac...amp=1105035450 I think Shoog did this one. Search and you can probably find the original thread. Sheldon

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