Hello Mates - Recently I bought a BHK Pre and BHK 250 combo. Now want to roll the tubes of pre and found a NOS GE 12BH7 in my local old tube shop. The person told me, I can use 12BH7 instead of 12AU7 in my BHK pre. Now, I need your expert suggestion should I use it? Any one as any previous experie…

I don’t know that tube per se (preferring to stick with the stock tube) but it will work. BHK preamp has the ability to switch heater currents via a jumper inside the preamp. You can go from the standard of 4ma to 5ma. If you can find out the appropriate current the tube wants, use this jumper to s…

Theoretically it should work if the BHK is capable of handling the additional heater current draw. I feel pretty certain that back when BHK was actively participating in the forum he answered this same question so you probably need to do a search. But you might also take into consideration that hi…

Additional to the above, you may discuss your query with PSA staff.

Thanks dawkinsj and Job_Jalink for sharing your thoughts. @Paul or any expert from PSAudio - Please suggest.

Thanks a lot @Paul ! You are a life saver. I’ll try and update the forum.

I would suggest you read through this thread starting at post #277

Here you go. [image] BHK Preamp tube rolling Amplifiers @BHK what is the max heater current that the BHK Pre can supply? I have found a wonderful sounding pair of Russian 6n6p (6h6n) tubes that are essentially 12bh7’s,… plot wise they work as the bias point falls …

I have successfully able to use GE 12BH7A tubes in my BHK pre after following @Paul suggestions. It working in both 4mA and 5mA jumber positions. But sound is more engaging when pur the jumper at 5mA. My experience with 12bh7a is wonderful. It turns my BHK pre to a new unit in better way.

BHK Pre Tube Rolling (using 12BH7 instead 12AU7)

Audio Components Preamplifiers

dawkinsj January 22, 2024, 4:32pm 9

Here you go.

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BHK Pre Tube Rolling (using 12BH7 instead 12AU7)

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