I’ve been listening to the stock tubes now for a while, so I’m getting an idea of a baseline. I have (3) sets of tubes on order:
Siemens & Halski 6DJ8 NOS
Tungsram PCC88/7DJ8 Used
Mullard 12AU7/ECC82 New
These should give me a variety of differences, so I can hear/validate directionally what I like given my current setup.
I’m glad you’ve become familiar with the pre per its factory spec. The factory tubes really are good. I get a little sad when I hear people swap the tubes before even hearing how we listen to it. Let us know what you think, should be a lot of fun!
Bascom has measured these 6SN7 as in spec at 600ma heater current I believe and he said the circuit can handle 1a. 6DJB vary from ~0.30A to 0.38A
12SN7 should draw 0.3A - http://www.radiostation.ru/tubes/6SN7.pdf
I should note I’ve had the pre for more than two years and it’s in use 12 hours a day. I’ve used up two sets of stock tubes plus racked up thousands on mostly 12AU7 family sets I hold in my stash.
It was time to venture out a bit. I feel the metal cover only serves to sink heat. Dust goes right through and I have no fear of little hands reaching in as it all lives in its own AV closet.
Specs: http://www.tungsol.com/specs/6sn7gtb-tung-sol.pdf
‘BHK: I have discovered that the heater supply in the BHK Preamp will support tubes with 600 mA heaters like 6SN7 (with 9-pin to 8-pin Octal adapters),
6CG7/6FQ7, 12BH7. I measured these in my original prototype and found that all of these want the 4 mA current setting - very important. Initially when I tried them out in the original preamp in the lab, they came up and worked but then the heater voltage started to go down. What?? It turned out that the heater regulator device was not screwed down tight to the heat sink. Tightening that, it all worked great.’
I absolutely agree, James. So many people seem to swap the tubes before they set any baseline with the stock tubes. That makes no sense.
Take your time. Listen for a month or two. Then when you swap tubes, you’ll really understand what the differences are.
Same goes for fuses.
Well, it happened. After 5 hours of play with the Tung-Sol 6SN7GTB the left channel became markedly noisy. Easily heard with ~65dB music playing.
No swapping of tubes rectified the situation. Did the 6SN7 stress an out of spec component? Seems so. Nothing smoked, no violence whatsoever other than the volume change bringing about those dastardly loud snaps - only in the left channel. Not damaging though. Always reduce the gain when trying tubes early to avoid burning out a speaker component.
Seems the channels are now wildly out of balance of gain. I’ve contacted support and we’ll get her fixed up I’m sure. The tubes will go back with the unit so they can test for the root cause.
I’ve enjoyed the BHK for 500+ days so far. The right channel has acted up twice before but it was fixed by swapping tubes left for right.
For the time being I’m certainly not suffering with the DS direct into amps. There are about 3x the number of gain staging steps now. Takes too long to find the sweet spot. The bass is cleaner but lacks the feel, the soul. The picture less multidimensional. But then the track will change and I’m transported away from this point in space and time…just a little bit more.
Some life missing from the aural presentation but not a bad flavor or spice. Just different. I’ve only ever had the BHK in the chain, well, in this current build of 3 years.
P10 - Pink Faun - DS - M700 - ATC SCM11v2 - Rythmik L12 sealed servo twin subs signal from M700. I’ve got 16 different convoling filter sets. I switch between 2-3 mostly. Thierry at Home Audio Fidelity worked with me to craft.
The real question is can I resist the temptation to run the 6SN7 again? They sounded great out of the box but trended down hill the more I listened until the left gave it up. The tubes are clearly under driven thus will take a very long time to settle.
I can’t recommend these highly enough. They’ve built an adapter of ultimate functional quality. 9 days from purchase to me from China. 4 layers of packing. Fantastic attention to detail. Craftspeople.
I also have a pair of bakelite 9-pin extenders. Solid but not the ceramic beauties above. They’re not strictly necessary to run the 6SN7 but the brass is a bit too close to the vertical servo board just each socket.
Ahh! I just realized I didn’t try swapping the servo boards! Heck of a lot easier to ship 1oz. vs. 40 lbs. Time to try it. Be well everyone.
Swapped servo boards, no change. Bummer.
Brett
Edit: Heads up, the 6NS7 killed the input board. PS Audio tech says the BHK pre cannot tolerate the 0.6a current demands despite Bascom stating they work just fine. Just a word of caution. They may work they may not…and if they do for how long…
My pre is back and breaking in the new input board. I won’t be risking it with 6SN7 again.
Anyone want a deal on 8-9pin adaptors and Tung-Sol 6SN7? 5 hours on them.
My favorite tubes for the moment are the NOS Brimar 12AU7. I was running the recently released Psvane 12AU7-S (successor to the 12AU7-II shipped with the BHK) for a few weeks, but it hadn’t opened up to the level of the Brimar’s depth despite being much quieter.
I just got a NOS pair of Valvo 7dj8s from Andy Bouwman, literally put them in less than half-an-hour ago, so they’ve just reached warm-up.
I threw all caution to the wind and installed my prized Sylvania VT-231s today.
And they are glorious.
I’ve owned these tubes for nearly 20 years, rotating two pairs of them in and out of my Cary SLP-98 (among other 6SN7 types…Tung-Sol, Philips JANs. GE, RCA).
They are running a little hotter in the BHK Pre than I recall in the Cary.
My preamp headed back to the mothership today for a tuneup. Hope to have it back soon.
I miss it. Loss of bass control is the biggest thing.
Quick update - after letting new tubes burn in a bit (50+ hours on all of them) and listening for several hours each day this week, all 3 sets of tubes I ordered are not quite up to par with the existing 12AU7s I got in the BHK preamp.
Summary of 4 different tubes. I like original Psvane the best. Close 2nd was a set of Seimens 6DJ8 from Andy @ vintage tube services in Michigan. They have slightly better articulation, and a little more punch down low, but slightly too forward. I could live with them, however, my ears get slightly fatigued after about 2-3 hours of listening. Last two were much further down the list in my liking.
Psvanes have a soundstage depth that I didn’t find in the others. They’re clear and smooth, especially in the upper midrange, in which the others were too forward.
Summary:
Off to find others to compare - I’ve got some Amperex NOS on order from Andy that may be closer to my liking. I’ll keep the Siemens as it is close to my liking, and may fit if I change other items down the road. From what I gathered, Psvanes do most of what I like; I would be interested in a tube slightly more articulate. I do need to balance this ask without the forwardness and glare in some tubes that can be fatiguing given my system.
@vee Based on your note, I’m debating if I should try the Brimar as well - you mentioned it has more depth; of the two, which was more forward in your system?
Hey Senna,
Give the nos telefunken 7dj8s a shot …got mine thru upscale…they might still have them…
I’d say the Brimar were slightly more forward. I was testing some noise-related changes to my system and swapped the Brimars out for the Shuguang 12AU7-TG. These Shuguangs are blacker and are also slightly recessed compared to the Brimars, but punch and pop in the low end are more pronounced.
So playing with these tubes again, I noticed a good amount of microphonics today, so I’m not entirely convinced I had a good set to start with - purchased from reputable friend, but had several hundred hours on them used. With that, I may give another set a try down the road.
That’s about how long them seem to last before sliding off the cliff
JJ 12AU7 really working for me here, no desire to change, which is always a good sign.
Affordable and easily available too.
Hey senna1a,
Tungsram tubes have been very short lived in my classic McIntosh MX110 all tube tuner preamp.
My MX uses 2 6u8s in the 3rd af stage…teles unobtaniums…tried tungsram 6u8s excellent sound.
But as has been experienced by some lifespan before getting noisy is but a few hundred hours at most. Tungram tubes got very noise with a “rushing wind” kind of noise.
Later read, wish I could remember where, that tungsram are very short
lived.
In contrast my old 1960s Fisher 800c receiver’s telefunken small signal tubes are still lively
performing above and beyond… Mind you I acquired my 800c in the mid 80’s with who know what kind of harsh continuous use …when my 800c pooped out…the 12at7s and 12ax7s still
playing strong along with tele 12au7s as well…in MX110z…and who knows how many hours these teles have on them…but many thousands for sure.
Just thought you might like another tungsram story…
Appreciate the feedback.
The jj reds 12au7 are ok. The Sylvania Conn 12au7 have a wider soundstage.
How are the VT-231 treating you?
The guys have identified the failed component on the input board. Waiting on parts and agreed to test with the Tung-Sol I sent back with the unit. It’s much appreciated as I don’t think I’ve be willing to risk using that set again otherwise.