12Bh7 in HT 1

Discussion - HT-1 amplifiers
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Posts: 4
Joined: Tue Jun 24, 2014 3:02 pm
Location: United States, California

Tue Jun 24, 2014 3:08 pm

Hello, I recently purchased an ht-1r and am looking to do some experimentation just because. Have you tried a 12Bh7 tube in place of the 12au7 ? I believe the 12B is the tube on the larger ht-5 but it appears pin compatible with a 12au7.

the ht-1r sounds great as it is from the factory but if you're reading this, you're afflicted by the same curious interest.

Should I do it ?

Have a great day

Posts: 11
Joined: Sat Jun 28, 2014 3:44 am

Sun Jun 29, 2014 3:17 am

I believe the 12BH7 has the same current draw as an ecc99. Both are pin for pin compatible. You need to make sure that the power transformer can handle the increase in heater current. Current is rated differently depending if a 6.3v or 12v heater supply is used. 12AU7 draws 150ma with heater wired to 12v and 300ma with 6.3v. ECC99 and 12BH7 draw 300/600ma if I recall? Have to look up the data sheet. Google it!

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