Hi everyone
I’m not sure if this is associated with faulty tubes or me missing something.
I recently bought a couple of sets of 6DJ8 tubes for my BHK preamp. I put them in and go no sound. I put the stock tubes back in and they’re fine so it’s not the preamp.
I’m thinking maybe I need to move the jumper or are the tubes faulty?
I’m not very technically minded so want to ask the question before I start fiddling with things.
Thanks
You have to move the jumpers from the 12v to the 6v settings and you may want to move the bias jumpers to the 5 milliamp setting. It’s in the manual.
Thanks. Maybe it’s me but the manual wasn’t clear.
Looks like my jumpers were already set for 5ma…
When it’s only on one pin like the attached pic from the manual, I guess this is 4ma and when the two pins are connected it’s 5ma?
There are two sets of jumpers.
The 6 series needs the 6v and 5ma jumpers set.
greetings, please read this thread that i started. my experience is that for whatever reason, the 6 volt tubes will not work well and can be problematic. if you are going to use NOS tubes, stick with the 12au7 or a 7DJ8
Anyone having issues with a noisy channel on the BHK preamp
Thanks.
I spent all day listening to the 6DJ8’s and I don’t like them. They sound harsh. I’ve put my gold lions back in which sound fantastic.
I also have some 7dj8’s here I’ll try next. Are they okay to run on 12v?
JH, the 7dj8 need to be on the 6v setting-12v is only for the 12au7s… good luck.
Thank you…
One last question I asked above but didn’t get answered.
Is the bias pin at 5ma when the jumper is on both pins? I assume the pic in the manual is the 4ma setting?
this should be helpful.
To the orig poster, I used Telefunken 6dj8 in my BHK pre. They are my favorite tube in that application and they work perfectly once voltage and current are correct.
Correct.
I don’t know where this nonsense about 6DJ8, E88CC’s not working in the BHK PreAmp came from. The amp is designed for them and they work fine. I have used many of these over the years with excellent results. Some can be noisy and those should be disregarded. Not all tubes are equal. Many supposed NOS are actually “Pulls” from old equipment. They may have many hours on them or none. Invest in a Tube Tester and you’re covered. I paid $150 Canadian for my B&K Dyna 606 and it’s like new and has saved my butt many times. My favorites after 3 years with the BHK Preamp are the Telefunken 6DJ8’s.
Why doesn’t the same occur with NOS 12AU7 tubes (as much as of course there are bad 12v tubes)? The 6v tubes demand more current.
Simple, the 12au7 is inherently a much better and tighter spec’ed tube than a 6dj8. That’s why you see it in great $10k pre’s and phono pre’s.
Whenever I mention 6dj8s to amp repairmen and amp designers, curse words fly out of their mouths. They are way too hit and miss. And the quality runs the gamut. I am sure that’s what led to having to develop 6922 and 7308s. I have 30 years with that tube and I have seen pre’s that simply will not turn on with them, but they test fine. I spend more time on a Hickok 539b testing, matching 6dj8/7308s than any other tube. Why do you think ARC and Sonic Frontiers used Sovtek 6922 in the 1990s? They sounded MEH but were tightly spec’ed and internally matched. They worked and lasted forever.
There are a ton of great nos 12au7s out there, even some new ones are OK. And you can concentrate on sound, not whether if the amp will turn on.
hey man, it is a surprise to me but when i got a set from Brent Jesse tubes, they were not at all compatible being very noisy and hissy. hard to figure as they should have worked. from his web site
7DJ8 / PCC88:
This is an unusual tube that must have had a limited range of specific uses. It is virtually identical to the 6DJ8 except for the heater rating, which is 7 volts
Kevin Deal has always recommended the Tungsram 7dj8 as their preferred tube for the preamp
Hi mate
Once I changed the voltage they were fine and not noisy. I just found them a little more brittle than the gold lions I usually use. However, I like warmer sounding equipment so maybe just not for me. Was worth a try.
Thanks.
these look very promising and are not that expensive.
I have been having a lot of trouble with MATSUSHITA / NATIONAL PCC88 / 7DJ8. They sound great except for the popping and clicking with the volume control.
thanks. never tried them but they are (or were) possibilities. i have had good luck with the Tungsram 7DJ8 from Upscale but they are no longer available.
