BHK Preamp tube rolling

I find your comment interesting. A couple of years ago I began selling-off my tube collection as I no longer needed them having switched to solid state. I went to list three matched pairs plus a single Tungsram 7DJ8/PCC88 that I’d purchased from Tubemonger: March, 1971 production. Anyway, I didn’t list them because I had a Post-It note on the batch that some of them had become noisy. This was within the first few hundred hours of use.

Those are two reputable sellers, guess we didn’t fare well with them in this particular case.

I’ve read others had similar experiences with these specific tubes. They sounded quite nice for a short while though, then got rather grainy/scratchy followed by noisy. Too much to tolerate.

Perhaps it’s specific to the BHK pre. I didn’t try them in anything else.

I don’t think that the BHK Pre is that hard on tubes I have Telefunken 6922’s and 3 years and maybe 5000 hours and they still test strong and sound good. I think it’s just that tube that’s got problematic longevity

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I had both the 7 and 12 volt Tungsrams go back after a couple of hundred hours in the BHK pre but the pair in the 250 were still going strong well past 1000 hours when I took them out just for a change to the Matsushita’s.

Tungram tubes only lasted about 300- 500 hours on my
McIntosh Mx110 z…these Tungsram were 6u8 pentode, triode

But they were almost Telefunken in sq…However read that Tungrams
were short lived…due to quality control problems…sad to say…

That seems to be the experience some are having here…

Best wishes

It was not the BHK preamp in my case. The single was used as the input for my (then) Conrad Johnson Premier 140 amp and the remaining six were used in my (then) Conrad Johnson Premier 16LS2 preamp. Neither model is in any way shape or form “hard” on its tubes.

Seems like much first hand experience with short service life with some NOS tubes. But that shouldn’t be a surprise as some of these Telefunkens and others are 40, 50, 60 years old, even if the word “New” precedes the words “Old Stock”.
My 6 volt Telefunkens are a couple years old and still wonderful. It’s just the luck of the draw.

Has anyone been able to reach Andy at Classic Tube Services lately?

I’ve been consistently calling him every day Tues - Friday for the past three weeks. After three rings I hear a click, and then it keeps ringing with no answer.

I hope he’s OK.

I spoke to him 3 weeks ago and bought 6CA4 rectifier from him
He did mention that he was about 6 weeks behind
He sounded a little rushed on the phone, but otherwise sounded fine

It did take a few attempts to reach him but his voicemail did pick up and state to call back on Friday as he was busy filling orders M-Th


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I used to get his voicemail, but lately I haven’t. I will keep trying. Thanks for the update.

Quick additional comment

I ordered the 6CA4 via phone on 6/4/21 Andy told me the shipping of my tube could be up to 6 weeks
Having not received the tube as of yet, I called today and got his voicemail, stating to call back on Friday

I’ll try him Friday, hope all is good with him and he is just behind due to high demand

A valuable resource for all audiophiles seeking both advice and fantastic NOS tubes


I’ve tried so many times to reach Andy that I’m fairly certain I’ve exceeded the official criteria for “stalking”. I’ve stopped trying.

He is a valuable resource for those who can reach him. I hope your sale concludes soon.

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I plopped in GL 6922s a few months ago and am very pleased with both price and performance. It was easy to switch up the thingy-mabob (technical term) in the pre-amp and get rolling.

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quick update:
I spoke with Andy this morning, he will be shipping my tube (1950’s Mullard 6CA4 rectifier, which he praised) on Monday

FWIW, he apologized for the delay and mentioned he was finally getting caught up and would be much more accessible (Friday seems to be the best day) by phone as he doesn’t care for email and frankly the website is in a state of disarray


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Very good news! Thanks for sharing. I’ll try calling Andy next Friday.

Very glad to hear this: I bought a pair, but haven’t put them in. Was enjoying for some time the gracefull, natural Matsushita / Nationals, currently loving the airy, spatial La Radiotechniques, and the Gold Lions are next. I think I will grab a couple extra pairs for my friend who is buying a BHK after hearing mine in his system.

I am super happy with the La Radiotechniques – much more so than a recent pair of Tungsrams from Tubemonger – but to be fair I’ve also moved from an AC12 to a Nordost Valhalla I (and flirting with a monster cable from a local manufacturer that seems to blow up – in the amazing way – every box I connect it to).

I just swapped in a pair of Sophia Electric 12AU7s in my BHK for my NOS La Radiotechniques. I’m very happy with them–tonally rich with great bass.

In the time since I originally posted my assessment of the Gold Lions, I’ve added Stillpoints SS footers under my BHK250 amp and Stellar P3 regenerator (in addition to those on my Tidal Piano speakers.) That change definitely increased system resolution and made any recording’s tendency for excessive sibilance or treble energy apparent. I still prefer original version Nasotec spike/shoe footers for the BHK preamp to the Stillpoints. Two weeks ago, I treated all power connections in my system with Mad Scientist graphene contact enhancer and that rendered a surprising amount of additional resolution. Differences between tubes are even more apparent now than they were before. Through all these changes, the Gold Lion 12au7s have sounded ideally balanced between warmth, resolution, musicality, and spatial resolution. I have been curious about the Sophia Electric 12au7s Andynotadam mentions, I may have to try them too after reading of his experience.

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What 12au7 tubes have the most universal praise for BHK pre owners? Gold Lions?

I’d say the Gold Lions are right up there! Great all around tube and much better sound then the stock tube IMO.

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