If I recall correctly the 12AT7 is not recommended for the BHK Pre.
That’s also my firm recollection.
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It wasn’t quite a circuit that would be plugged into a tube socket it was a completely different design solid state front end. Either way Bascom convinced Paul that the tube provided the best performance.
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Just going by memory a 12AX7 has 5X more gain than a 12AU7. Not a good combination for a circuit not designed for it.
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You got that on the nose. The mu (amplification) factor for a 12AX7 is 100 and it’s 20 for a 12AU7.
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a little advise as a user of bhk preamp, in the newversion at certain time later, possible to come with 2 pairs of XLR output that would more benefit in some cases
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This exchange reminds me of one I had years ago. I had a Berning TF10, and had a question about it, so I called Berning. When they answered the phone, I started rattling off whatever question I had, and asked to talk to the tech department. The guy on the other end said: “this is David Berning.” He was very nice, and open, and wiling to chat about my preamp. He told me it was one of his favorites. He recommended to me to try NOS RCA 12at7s, as they were his favorite tube in that circuit. I did, and he was right. Tube rolling used to be more fun, and much cheaper that it is today. I used to drive to small towns that had an older TV repair shop, looking for NOS tubes, that they were usually happy to sell cheap.
I hope to go to Boulder soon. It would be a real hoot to meet you.
Reverently,
Mongo
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Just replaced 12AU7 Gold Lion with these new tubes never heard before:
TAD Tube Amp Doctor 12AU7 Premium Selected (balanced) matched pair
I find them the most silent tubes ever listened on the BHK Preamp, really impressive.
Less warm than Gold Lion ones and very neutral as the PSVane stock.
I feel they work better in mids, voices and guitars more revealing realistic and vivid. Basses are less tight and present than GL. On the high side no difference audible to my ears.
Just 3 hours so I need more time to better understand.
Cost is very affordable and German service is speed and professional (I usually buy GN from them but this time I gave their brand a try and is IMO recommended).
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Nice!!
Best,
-JP
Glad I gave these 12AU7 Raytheon/Baldwin tubes another try. My first impression was they were too mellow, and not incisive enough. Decided to give them another go after my BHK 250 was re-bissed, and spend more time, if necessary, fine tuning speaker placement. Just swapped them in today, and made some minor speaker placement tweaks, and I’m really enjoying the sound. They may be slightly rolled off in the frequency extremes, which is why I toed my speakers in a little more, but boy the overall tonality is much more realistic and believable now. Also hearing subtle details that were only hinted at with the stock tubes. Additionally the presentation is more impactful, and richer sounding, breathing a greater sense of flesh and blood musicians in the room. These tubes are definite keepers.
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so far the best 12AU7 I’ve tried are the wathen 12AU7-WCL (long plate) they were/are unlisted on their website I tried the standard 12AU7-WC because someone had left a review stating it was similar to the Cifte 12AU7 and after comparing them I’d have to say that they are correct. I had messaged them asking if they had any other 12AU7’s and thats when they informed me they were going to be releasing a long plate version. I loved the standard so much I placed an order for the long plate version and asked them to ship when they came out.
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I’ll have to research some of the newer tubes shared recently - Thank you for the recommendations.
After rolling various sets over the last year, Ive landed on the following:
I have a set of butt ugly Amperex 6V from Brent Jesse in my streamer (with one backup set that need break-in).
I have a set of the early 60s Amperex bugle boy 12V in my BHK Pre with one back up set.
I have a set of Mullards in both 6V & 12V. They are as good from a tone perspective, but slightly more laid back & slightly less dynamic than the Amperex.
I do think it is very system dependent, but for NOS, the Amperex do seem to be nice middle of the hall (maybe front 1/3) type tubes with very good dynamics.
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absolutely system dependent the 12AU7-WCL work best (so far) with the First Watt F8 while the Grant Fidelity 6SN7-SE Globes work better for the Pass Labs XA25
Where did you order the Gold Lion 12AU7s from?
I have a set of gold lions for my BHK but I’m currently using Tungsram NOS tubes. The Gold Lion’s that I have I purchased from Upscale Audio.
Hi @Gary_M
Please note, that turing off BHK Pre and back on within less than 5 minutes could make the tubes cause a whining sound. I have had this with both PSVANE and Genlaex tubes. I attribute it to power cycling rather than bad tubes! So, if I turn things off, I make sure I wait before turnign than back on too quickly, and all will be fine.
Russian made Genalex Gold Lion 12AU7 has been working perfectly for over 2000 hours!
I got mine from these folks and was happy with their sale service:
Genalex Gold Lion Pair 12AU7 | vivatubes.com
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I was enjoying the Raytheon/Baldwin 12AU7 tubes, but one of them has started to get noisey, and makes a clicking sound when adjusting the volume on the preamp.
Think I’ll try a pair of the Gold Lions. Thanks for the link.
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The noise is an issue but the clicking sound maybe not so much.
This is what Kevin Deal said about the Siemens E288CC (a 6922 variant):
“If used in a preamp or phonostage, you may hear a slight “ting!” through your speakers when you move switches, or tap on the unit. This is normal.”
You might want to try re-seating the tube in question a couple of times as the noise may be due to some corrosion on the tube’s pins.
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I have a pair of Telefunken AU7’s from the 60’s on route from Andy at Vintage Tubes for the BHK pre. Recently got similar vintage tubes, Amperex “Bugle Boy” for the BHK 300’s and like them over the stock tubes. I will let you all know what I hear soon.