“more of everything” is a good description of what my limited experience has been with 5mA and 12AU7 tubes. It may become fatiguing over time but for the moment I am enjoying 5mA with GE JG-5814WA tubes and my Aric Audio Super 300B SET. But I have almost a dozen tubes I am going to roll in and the reason I asked if a consensus opinion had developed is because I don’t want to listen to each tube twice.
As an aside, I have also found there is a difference using the RCA output from my DAC versus the XLR output of the DAC into the BHK. RCA is smoother, less detailed in the top end, and probably a bit more pleasing for female vocals. XLR has that more of everything quality. The differences are noticeable but modest. I am using Harmonic Technology Pro Silway cables with both.
After how many hours do you recommend changing the tubes? I last changed 2 years ago and I just looked, over 6000 hours. It seems Ive lost a bit of gain. Is that a sign to change? No idea what is in there now. But I see 4 spare sets of tubes in my box. I will be ordering more haha. Your help is appreciated!!
Noise. If I detect an audible increase in the noise floor, I start thinking time to replace. I don’t recommend any canonical rule of thumb for hours of on-time to replacement. A good set of tubes can last a very long time indeed. It isn’t overly unusual for tubed gear to run on the same set for a decade. Be lucky enough to get tubes from a particularly good lot and you can forget about fretting over a usage counter. If they are still quiet and provide enough gain, stick with them. You’ll likely be better off since the set you replace them with may not be from a strong lot (manufacturing variation from lot to lot does matter). Grading only characterizes beginning of life, doesn’t characterize longevity.
MUCH appreciated Owlsalum! I ordered a pair of matched gold lions after reviewing the last parts of this thread. But I will hold off on doing the replacement. THANKS!
Guys, if you want the best tubes for your BHK Pre, buy ECC80 Philips D getter Pinched Waist WK6 or WK4 codes. They blew out of the water every 12au7 I tested and I got all of them
Tough to find NOS pairs, I have wanted to try some ECC80’s in my linestage for some time. So far, the Siemens 5814 triple micas are my personal favorite, followed by the G73R’s
The Phillips and re-brands from Phillips/Heelen have the gold pins, correct?
Hi, I’m hoping to resurrect this thread to ask a question. Has anyone done any objective (measured) testing between the gain obtained with 12AU7 versus 6922 (and variant) tubes in the BHK Preamp? I realise that 12AU7 and 6922 tubes have different quoted gains but I also realise that the BHK has different voltage and current switches with (might) affect the overall gain in the system once they’ve been adjusted. Also, given that the unit is a hybrid Mosfet / tube unit, the differences may be negligible.
I have lots of Telefunken 6DJ8’s and really love them but I’m also looking at some 12AU7 variants to role. I don’t have the original OEM tubes to test so I’m hoping that someone might have some insight into the gain. I am struggling to drive my Pass Labs XA25 as it has quite a low gain as well. Don’t want to get some 12AU7’s and lose even more gain!
Really loving my BHK Preamp. When I first got it, I said it was a keeper. That was 5 years ago and I have no intention of ever selling it
Mark
