BHK Signature 250 or 300 Tube Rolling

If your tubes are on, then they are burning hours – music or no music. Put it in standby when not listening, and you shouldn’t go through them so quickly.

Thanks jmeniche. If so, that easily double the tube using time. So nothing wrong with my amp, a priori. However, I’ve heard that switching on and off audio tubes very often may kill them faster than keeping them on. Is that a legend?

It’s pretty remarkable how generically transparent the 250 is with using the stock Genelex tubes. The Tungsram’s increase midrange resolution and dimensionality, but roll off the highs and the bass gets a bit boomy. I end up with a much more colored sound. I tried a pair of Amperex gold pin 7308s and they had they most clarity, resolution, air and dynamics, but got pretty bitey and shrill in the highs and uneven/thin in the lows.

For the moment I’m back to the stock tubes because they are the most versatile with different types of music, until I can find something better that is balanced and extended from top to bottom like these Genelex, but sounds better. I’d be interested in Mullard’s but every one I’ve used in guitar amps and pro audio has been very warm, but not exactly full range. Telefunken are way expensive…

1 Like

@watchdog507 Are the Telefunken’s that you recommend NEW or NOS?

NOS I didn’t know that there was new production.

Thank You!

The current production Telefunken 12au7 is in my BHK pre, sounds excellent.

The tubes in the Preamp need to be triode matched as well as matched pair to avoid the noise with the volume control. I learned the hard way!

Pardon my ignorance, new to tubes…How does one assess how many tube hours you have? Can not find reference in forum or BHK/300
manuals.

I use the timer in the BHK preamp. If you added your amp later you can reference the preamp counter and jot it down. For example if it shows 330 hours and 10 minutes that would be your starting point for 0 hours on the amp. If you replace the tubes in the amps at the same time as the preamp than reset the counter and it would reflect the actual hours on all the tubes.

The BHK preamp has a timer but, alas, the BHK power amplifiers do not (because they do not have a screen). I just figure that I play the system enough that I change them each year. For me, it’s spring when I make that change. I also change my water filters
under the sink once a year….which reminds me…

2 Likes

Ian, I totally agree with your comments about the Tungsrams being a little rolled off and boomy in the bass, and despite rolling a number of different tubes, came back to the Gold Lions, as well. They are hard to beat for new production.

I was curious if anyone on here had actually tried 2c51 / 5670 / 6n3 type tubes via adapter?? I’ve had great results with these too in other applications. I saw someone else post on it, but there were no comments to follow. Any thoughts or updates would be appreciated!

Just managed to swapped out the stock tubes on my BHK250 for a pair of National 7DJ8s.

1 Like

How do they sound? the National 7DJ8.

They’re Matsushita. In the BHK preamp, they sound very neutral, quite similar to the stock Psvanes.

Thanks Ron,

It’s so nice to have someone who have tried so many tubes on the BHK Pre. It would be nice to have a post with summary of all the tubes you’ve tried, when you have time :smile:

I’ve seen some posts about using an adapter to be able to use octal tubes such as 6SN7s. However, I have been unsuccessful finding such an adapter on line. Any suggestions? I have quite a hoard of great 6SN7 NOS including the Sylvania Ws, which I was going to sell on Audiogon, but would like to try in the BHK pre and 300s to see if I should keep at least some of them. Thanks

Her you are:

you may not have clearance inside the amp though.

Thanks for that. I understand that height may be a problem, so will first try in BHK pre, probably with tube access cover off.k

6SN7’s come in a variety of form factors. If you source short bottles versus tall bottles you may be OK.

There’s no inherent advantage to either that I know of.