Hi folks, I’m waiting for a BHK pre delivery next week, wanted to know what are the compatible 6v or 7v tubes. Customer service’s reply leaves me scratching my head
“ Basically anything that uses the same tube pinout as the 12AU7s (the tubes included with the preamp) and either 6, 7, or 12 volt. “Thanks in advance
Welcome. 6JD8, 6922, 7308, 7DJ8 to name a few majors.
I’ve enjoyed the BHK pre for more than 3 years. It’s a fine unit.
You’ll find volumes of information here: BHK Preamp tube rolling
My favorites tubes in the pre are in the 12v family. 6v and 7v tend to be noisy or not last long in my unit. Each unit will have a tolerance so don’t be afraid to try. Just know that is was intended to run 12AU7 or compatible tubes with the secondary ability to run 6/7v. Others have had a great experience with 6/7v tubes but they tend to be some rare, expensive versions.
Don’t discount the stock tubes. I would give them 100 hours playtime. They need a few hours to settle and more importantly so does the preamp.
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My BHK Pre for the most part has had 6DJ8, 6922 and 7308. That said I have Telefunken 6922 tubes which have gone up stratospherically lately. I have tiny tube hiss with an ear beside the tweeter and 3 years old in the preamp and running strong.
I agree the NOS Telefunken from Ulm and I believe one other location are silly expensive. Forget the CCa. Super tough to find and pricey but those the have them are pretty happy.
I have a pair of Telefunken ECC802S from Ulm, 1965 that I was fortunate to purchase 2nd hand and originally from a good source (Brent Jessee) and they’ve not disappointed me.
They can be a touch dry and a warmer compliment for the BHK amp is one the way. Amperex Holland BEL 6922, 1960s. I may try them in the pre in the future.
I’ve picked up some Telefunken 12AU7’s and I may give them a whirl when I take everything apart for a good cleaning. It should be interesting as a comparison, especially the background noise. My speakers are 91db so fairly efficient for big boxes.
Thanks for your feedback, folks, now I know which way to go, of course I still have to like the thing, can’t even sleep 