Changing Tubes to Tungsam PCC88/7DJ8

My dealer, Upscale Audio, who just bought a new BHK preamp included a few of his recommended tubes he picked up in Europe. I gather that I have to adjust a setting to the voltage jumpers before I can use this different tube…correct? I looked under the ‘hood’ and I am not sure what I am looking at or what I should do to change a jumper setting. I see the black jumper. Do I pull it up and shift it over one place (looks to be a single small pin next to it)? Anyone out there can advise me? I rather not plug the preamp in only to see it go up in flames like a Samsung smart phone. Thank you!


Posts 175. - 177 , Pg10 in the pre-amp manual. It is easy to do, 2 jumpers (1 current, 1 voltage - not per channel / thanks)

Thank you Frank!

Instructions are in the BHK Pre manual along with pictures. As Frank states, it is easy. Good luck, Kevin

Bascom King recommends changing the current jumpers as well when using the Tungsrams (or other 6922 types), although they will work without changing them. So that would be two jumpers per tube. Both are shown in the instructions.


Stevem2 is correct, you should switch the both the current jumper and voltage jumper when switching from 12AU7 to 7JD8 tubes. According to the manual there are 2 jumpers, one for current and one for voltage.

I did the voltage jumper yesterday. I will do the current jumper when I get home tonight after work. I assume the current is like the voltage. Pull it off and shift to right or left depending on what you are facing (front or rear) . The factory installed tubes came out without too much effort which was a pleasant surprise.

Yes that’s right.

The current jumper with the 12AU7 tubes is just hanging on one pin so it’s not actually “jumping” anything. To use the 7DJ8’s put it over both pins at that location. It will be obvious when you look closely.