BHK Preamplifier Tubes

PS Audio:

Respected HiFi Dealer Upscale Audio claims the BHK Signature Preamplifier sounds best with TUNGSRAM PCC88 / 7DJ8 tubes. Some in the PS Audio community agree, others do not. Regardless, they have become extremely difficult to find.

Which non-stock tubes does PS Audio (and/or Bascom H. King ) recommend as a tube “upgrade” to the BHK Signature Preamplifier?

BTW, where is the Black Friday/Cyber Monday/Holiday Sale???

Thanks,

Byrdman

The best tube that I have used in my BHK Pre is hands down the Telefunken 6DJ8. That’s with testing at least 10 different and well respected NOS tubes. Unfortunately the prices have almost tripled from 2 years ago.

Try some other tubes for yourself. I am of the crowd who feels the Tungsram are way over rated. I am currently enjoy ing the
Conn/Sylvania 12AU7s.

I recently purchased the Brimar CV 4003’s NOS for my BHK preamp and I’m very pleased with the sound!

The prices are crazy, but the Tele 6dj8’s are my favorites also. I liked them so much that i bought a spare pair.

I bought a pair from Andy Bouwman, Vintage Tube Services. It was a mistake (and a waste of $$$) to buy others first.

IMO, there is no “best” tube for the BHK preamp because we listen to a system, not just a preamp. All the other aspects of the system greatly influence one’s perception of “best.” I’ve had a BHK pre in my system for a few years and every time I upgrade or change something up or downstream from the preamp my opinions about tubes in the BHK pre and BHK250 change somewhat. For the longest time, I thought the Telefunken 6DJ8 was the best sounding tube in the BHK. Then I added Stillpoint Ultra SS feet to my Tidal Piano Cera speakers and I found RCA black plate square getter 12AU7’s to be my preference. Even a changing the power cord for the P3 power generator powering my front end changes what I prefer in tubes.

1 Like

Curious if you have a tube recommendation for the BHK 300’s as well?

In my BHK 300’s I used Philips Miniwatt 7308 and I now use Valvo 7308’s I don’t have a quad of Telefunken tubes or I would use them. Siemens E88CC’s are also great tubes.

Bascom initially recommended the same Tungsram tubes as you link to. I have two sets of them myself, but now I use adapters to use Sylvania VT-231. It’s just as musical with better performance at the frequency extremes.

This topic has been well covered. You can read suggestions for days:

There is a lengthy thread in the forum dedicated to BHK Pre tube rolling. I will say Kevin pitches the NOS tubes that he sells, of course, as the greatest. See that other thread and then decide yourself by buying and trying. I can say the Tungsram’s Kevin pushes aren’t for me. My take can be found on the tube rolling thread. Upscale Audio is definitely not the only good, reliable vendor of NOS tubes.

BHK here,

I was doing some testing with my tube test circuit on the BHK Preamp input stage circuit to test out some some very old tubes, 12AU7’s in particular. Wow! I found two pairs of RCA 12AU7’s that tested out OK. When I put a pair in my BHK preamp, Would you believe, that they sounded a lot better than the stock Pvane I was using! I also found a pair of Telefunken that tested good I will listen to those soon.

As another interesting piece of information, I was testing some Tungsram 7DJ8’s in the BHK Preamp tube input circuit and found that they seemed to test about the same at 4 or 5 mA plate current. So it might be interesting to go to the 4 mA setting used for the 12AU7’s for whatever 6922 varient that you are using to see what happens to the sound and also if the volume control starts popping when changing volume. Would like to know what you find.

7 Likes

Thanks for the feedback @BHK. I have a set of clear top RCA 12AU7 and do enjoy them.

I have tried 4 mA for a handful of the 6v variants and actually preferred it to the 5mA for my specific setup - I have not noticed any popping and seems to work in my case.

Good to hear from you @BHK !

3 Likes

Right now on a pair of 7308 Amperex USN-CEP '64 with 5ma. No pops or clicks here, with the lowest tube rush so far!

Is there any difference regarding lifespan and tube health using 4ma bias for a 6v/7v on the BHK preamp? Or is the move to try 4ma bias for 6v/7v only related to avoid the strenuous sound and lower tube rush?

Thanks

P.S. I have pair of TFK Ecc88 '68, that also sounds phenomenal. My preamp probably has more than 10,000 hrs of use with different 6,7,12 volts tubes. What an amazing piece of gear and lets not forget that it is a great headphone amplifier too!

1 Like