I had a very low constant tube rush with 6,7,12 volts either way. My speakers a 91db and I seat near field anyway. But I do feel that the higher amplification factor from 6,7 volts tubes vs 12v valves gives you that extra tubbiness we are all looking for.
I never venture on trying 4ma bias on 6,7 volts setup. Any word on that?
The preamp was conceptualize under a 7DJ8 (Tungsram) tube anyway…
I agree completely and I tried a lot of 6 and 7 volt tubes all too noisy in the BHK though fine in another preamp.
I have been using -10db attenueator at the amp input to lower the SNR either way(12vs6,7)., but been 12v since the beginning with the BHK but I have been enjoying(att) and 7DJ8 is quite a bit.
P.S. I did break in the attenuator for a while on another system full volt
jaime, I’m also using a 10dB attenuator at the input of my BHK 300s.
That’s what I thought you had(att). Cool.
I did experience different amount of hiss/tube rush within the 12v family anyway.
The Toshiba 7DJ8 are surpricingly quite, even less hiss/rush than other 12v that I tried.
Like many on this thread I was totally in love with the NOS Amperex 7308. The sonics really are great. However, after a couple hundred hours I too noticed some odd sounds like wooshing. Nothing too terrible, but also the volume adjustment had fairly noticeable audible clicks.
I then tried some NOS Cifte 12AU7 from Upscale and these are really crazy good. Dead silent, no volume clicks (near perfect matching here I think) and as good or better sonically. I will almost certainly be purchasing a backup set. A bit pricey ($300/pair for cryo, best matching) but still consider this good value assuming a long life.
My 2 cents.
Is there a final word for the bias jumper setting of 4ma/5ma for a 7DJ8/PCC88?
Heater currents specs;
7DJ8, 300ma
12au7, 300ma
6dj8/6922, 365ma
7308, 335ma
That is interesting as in my BHK preamp 12 volt tubes are probably 6 to 10 db lower in tube rush. I like the Tungsram in the preamp but can’t stand it’s tube rush which is audible from my listening position. It is definitely louder when set to 5 ma bias which makes sense. The 4 ma setting still does not make it acceptable to me.
Curious about your use of the 6ns7 in bhk preamp, its not pratical but i dig the wonky things plus my equipment is on a rack so I only see the faceplates anyway. how do you have the bhk configured to run them? since the 6ns7 is a 6v tube would it be better to get a 6ns7 to 6922 adaptor or does it not matter cause you can just change 6-12v with the jumper. how does it sound vs other tubes you’ve tried?
That’s exactly what I used, a 6SN7 To 12AU7 adapter, plus a socket saver to raise the tube up away from some components since the tube diameter is much larger than the smaller signal tubes like the 6922 and 12au7 family.
Highly recommended: No connection, just a pleased customer.
I really like the NOS Sylvania tubes this same guy sold too.
Yeah, everything I’ve bought from him has been top notch and reasonably priced.
Comparing the Sylvania/Baldwin/Conn to the GE, the GE have that je ne sais quoi that makes them ‘better’ to me.
I’ve also got a set of 58 CBS 5814WA too. I haven’t tried them yet. My stash is in good shape for at least a few years now.
Wow you like the GE more than the Sylvania. I guess I am going to have to get a set of those to add to my collection. Thanks for another good lead!
The black plate Raytheon’s are really good in the BHK too. I bought six pairs of 59-60 triple mica black plates from a widow of an electronics repairman about 5 years ago. Also worth trying the Baldwin labeled Toshiba tubes too as they were probably made in the Matsushita plant.
Didn’t take you guys longs to snatch up the last of the GEs. Enjoy and let us know your thoughts after a few hours of play. My set didn’t take much time at all to ‘settle’.
The Sylvania needed a good 100 hours to stop changing.
Matsushita 7DJ8 BHK Preamp
Reflektor 6n23p-EV '75 OTK @ BHK 250
great pairing
Tried them both and too noisy for me in my system with the BHK 250. The Matsushita is great though and currently in the 250 amp.
I recently tried Brimar CV4003s in my BHK preamp, and was surprised by the difference they made compared with Psvane tubes. The Brimars have a tighter bass and much more resolved mid range in my system.
Out of curiosity: for those of you who swap out tubes fairly frequently, how do you keep track of the use on each tube?
Bob
I too have used Brimar CV 4003s in my BHK Pre. Without question better than the stock Psvanes. From my previous posts you’ll see my overwhelming favorites are NOS Tele 6922s, which are out of this world good. One thing so many of us find is the stock Psvanes don’t do the BHK justice. Frankly surprised with all this feedback PSA continues to ship with Psvanes. I’ve even tried new stock Gold Lions that are better. Enjoy with the Brimars! Excellent tube choice. I track time on my tubes with a spreadsheet. I’m not concerned with getting down to the nearest hour.