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Audio Research tube problem with Aragon 4004 MKII

Retubed my SP 8 and the tube company had no 12bh7s, but showed an Ecc99 as a direct substitute. Put the new tubes in, got a low volume buzz through both channels, and even though the volume was down, my Aragon 4004 MkII sparked and died. Tube company says they have had to problem with that substitution, but has sent a different 12bh7. (Replaced my original in a makeshift system, and it worked fine with the old tube). Anyone had any experience? Have heard Aragons had some sensitivity to DC offset, and my 4004 has had the relay chatter numerous times in the past making me wonder whether it's protection stage was adequate.
chidancer

Showing 1 response by johnss

johnss
564 posts
 
I had a similar problem as Kenscollick did.

If you are set on using a tube pre with the 4004, you'll need to add a DC blocking cap for both channels. I know' direct is supposed to be better, but in this case, your options are limited. Add a film cap to the 4004 inputs and enjoy your tube pre.
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