I would submit that those who just can’t live with tube hiss with their 6v and 7v tubes try the 4mv setting and make up their own minds. (My RAM 6922s are enjoyable with either bias setting.)
But, above all, seek out low-noise tubes from a trusted tube seller.
Yes, I also have a set of Roger’s RAM low noise 6922 Russian tubes and they are quite quiet. They are also not bad sounding tubes at all, just not the last word in lushness if that’s your thing. I had a phone conversation about 6dj8/6922 tubes with Roger when I ordered them and he mentioned that he had to test a LOT of tubes to find low noise noise examples and it could be exasperating trying to find good ones. He felt that when the good ones were identified, the primo Russian examples compared well to NOS tubes that audiophiles revere.
In a quest to lower the background/idle tube hiss (which measured ~46 dB at the tweeter/midrange) with my Tungsram PCC88s in my BHK pre, I just installed a pair of XLR -10dB barrel attenuators at the inputs of my M700s. (Parts Express: $10 ea.)
If BHK pre users must have profound silence between tracks – or during ppp passages – I can report that these things accomplish that. At least with the Tungsrams (which were supposedly balanced, matched and “low-noise”).
I’m being critical… and trying to hear sonic tradeoffs with these. I haven’t noticed any yet (with my ~94 dB-sensitive speakers).
YMMV, or course.
What is the resulting dB level with the attenuators added?
I didn’t measure it originally because I couldn’t hear squat lol.
But I just did now: 24dB. And that’s with a “leaky” 4’ x 4’ window in the room.
Anybody tried the precious Treasure Globes?
Just trying to sort out all the tube nomenclature. Is the following right?
12AU7=ECC82=CV4002
So, any tube with either of those three descriptors will function appropriately in a BHK preamp. BTW, please add to or correct this list.
Thanks.
Cheers,
BobOthers may jump in with additional info, but here’s the reference I use for what’s works without adapters, etc.
12 volt:
12AU7/ECC82 (CV4003)
Grid Frame 6 or 7 volt:
6DJ8/ECC88
6922/E88CC
7DJ8/PCC88
7308/E188CC
Others like the 6N7S have been successfully used with adapters and opening the top.
Thanks. That’s just what I was looking for.
I too got attenuators. I got Whirlwind attenuators (-10dB) and am very pleased. I did get a sonic trade off but definitely not very significant. It allows me to increase the gain on my preamp so I feel that this makes up for any musicality lost. Very good find.
I was one of those that needed complete silence as my Hifi and Home Theater setup are one. I can’t have a bunch of hiss during quiet parts of movies hahah. That would rob it from all the magic!
I really don’t get why some have excessive hiss. With12au7 tubes my preamp is extremely quiet so much so with my high sensitivity speakers I have to put my ear by the tweeter to hear it at all. I get the hiss complaint when running 6 volt tubes though.
12au7s are no problem here.
6 and 7 volt tubes are a “little” noisier, but may not bother some. I demand silence, so the attenuators work for me. YMMV.
As an aside, xlr attenuators left at the inputs will also attenuate the rca inputs by the same value. Do not run both inputs with two pairs of cables or bad things could happen. It’s OK to leave the xlr attenuators in place after disconnecting the xlr cables.
This works with the Stellar M700s. I can’t comment on the other PS amps.
I have a bit less with 12V tubes, but the sound is much better with the Tung pcc88s.
The attenuators didn’t the trick for me too
I guess that is a matter of taste. I was not particularly impressed by them. I much prefer the Conn Sylvania 12au7’s. They are way quieter and have a wider soundstage as well as bass without the boom of the Tungsrams.
I have tried close to two dozen different tube pairs in the BHK preamp and the Tungsram’s were the worst. Not only noisy but edgy. They are o.k. in the amp as was recommended.
Interesting. I have some Conn Au7s as well. Maybe I’ll go back to them a see what I think. For now with my setup, I find the tungs better.
It’s all going to depend on the rest of your gear plus the sound you like.
Of course.
I’ve got all PS audio DAC, Preamp, BHK250. Tekton DIs.
Will report my findings later
I just adore new tube day every few months or so. These sound more than decent straightaway, literally 10 mins warming up. The ups and downs of the next 100 hours or so will be interesting. Some say ~300 hours before they settle.
Tung-Sol new stock 6SN7GTB
I don’t care to try a tube that pushes the current limits of the preamp and does not fit under the cover. i don’t want an adapter between the tube sockets and the tubes.
