I didn’t get any from Tubemonger, but I did get an additional set from The Tube Store. I have not tried them yet. They ship internationally as well, and the owner has always been very helpful to me.
Another vote for The Tube Store. Great people with excellent customer service.
I posted the question to tubemonger regarding their statement.
this is the response i got.
"
That means for this tester 7500 mmhos test score means the 65% of the value as compared to the average new.
Most of these tubes test over 13000 mmhos, that is over 100%."
Anyone explain in simple language? I am confused with the two sentences.
Does it mean they are good to use?
ksquare. The tubes in question have already had 35% of their useful lifespan depleted. 65% remains which is not an ideal number… To quote BHK from his post above…“if they in fact have a amplification of 65% of normal, they would not perform well in the BHK amps or preamp.” BHK would certainly know. I would not buy them.
I am not sure that’s what the mmhos measurement means. If it was a lifespan issue, then the cheap price might in fact be a fair value, and the purchase might be reasonable. Instead of being good for maybe 10,000 hours, they might only perform well for 5,000 hours or so. Not necessarily bad. However, if the transconductance reflects that the tube is only operating at 65% of its nominal NOS capability, then like BHK, I suspect it won’t perform well.
Further clarification from tubemonger.
Confirmed they are not operating at 65% of normal amplification. And that
“65%=7,500 is a reference point for the tester on which these were tested. All test over 13,000 mmhos”
with this, i have just placed an order from them. Looking forward to receiving them.
Separately, i have just got the following 3 sets of tubes from the local store :
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amperex 7308 made in holland (it has a white globe logo on the tube)
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valvo e188cc
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siemens e188cc (7308)
replaced the stock psvane with the siemens in the pre. Burning in.
Any one try the Siemens cca?
palerider said I am not sure that's what the mmhos measurement means. If it was a lifespan issue, then the cheap price might in fact be a fair value, and the purchase might be reasonable. Instead of being good for maybe 10,000 hours, they might only perform well for 5,000 hours or so. Not necessarily bad. However, if the transconductance reflects that the tube is only operating at 65% of its nominal NOS capability, then like BHK, I suspect it won't perform well.One unfortunate thing not being mentioned here is that noticeable deterioration of the sound of tubes in a circuit can occur way before the transconductance in mmho decreases measurably. I remember one thing way in the past with a pair of Marantz 9 tube amps that I had periodically borrowed from Jim Bongiorno. They had got to sounding rather thin and non-involving but yet measured perfectly fine in my lab. I got a new set of NOS EL-34s from Roger Modjeski and the sound went from the thin and uninvolving to robust, wonderful, and full sounding - and measured about the same in the lab.
In the case of the tubes in the BHK amps and preamp, that middle hundreds of hours or so would be a good time to try some new tubes of the same kind to check to see if there is any sonic improvement.
Excellent reminder Bascom. Thank you.
Tubes. Damn you tubes. And other beautiful things that drive us nuts.
ksquare said
with this, i have just placed an order from them. Looking forward to receiving them!Congrats! Enjoy!
I do enjoy the Tungsram’s in the 300’s. I have a pair of Golden Lion 12AU7’s on order for the Pre. I am at 1127 hours on it so far.
Hi guys,
Very new to tubes so apologies if i am asking some 101 questions.
been playing around with the 3 sets (siemens, amperex and valvo) of tubes i bought from the local store while waiting for the tungsrams to arrive.
i noticed some differences operationally.
Sound from speakers. I can hear some hissing/buzzing sound when i put my ear near the speakers. Some quieter than others. Amperex is quite bad, i could still hear a buzzing sound from my seating position which is about 8 ft away.
sound from the tube. Siemens and valvo are the quietest. The stock tubes are the loudest followed by amperex.
are these normal and is it because they are new and will need time to settle in?
I have just gone through the other thread about new tubes and hiss.
so looks like the siemens and valvo are operating normal with hiss/buzz only audible when your ears are next to the speaker.
this then means there may be an issue with the amperex… ?
I dealt with Andy at Vintage Tube Services to tube up my BHK 300 and my Blue Circle Pre (both take 6DJ8/6922s). He recommended Amperex A-Frame 6DJ8s from the 1970s. He makes a big deal of sorting to match and to identify low noise tubes that he rates for moving coil phono stages (these went into my preamp) He also argues that cleaning the pins properly on vintage tubes is essential, and he follows an elaborate process. I’m delighted with the results. My BHK300s sound like new amps and for the first time I really hear from these amps that touch of glowing extra sustain that enhances the illusion of real presence. Meanwhile, the bass is better defined. (The A-frames were chosen over the 1960’s “Bugle Boys,” because the former are more linear, i.e., better for letting the Magicos do their thing.) For the price of a power cord I got a major (and fun) upgrade in SQ. Note the Hewlett Packard branding, which I’m told is a little uncommon.
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Question for Bascom. My BHK 300’s have just celebrated their 1st anniversary. Because of the problem of tube life I keep the amps in standby-mode when not playing music. Used this way, I find it practically hard-to-impossible to keep tabs on the number of hours on the tubes. I am wondering if there is some reason from a design perspective why an hours-counter wasn’t incorporated in the product?
I am concerned that tube wear-out may prove to be an insidious process, one that is difficult to detect unless something changes pretty dramatically over a short period of time. Does anybody have any comments on that?
Just for clarity, I have no particular reason to suspect that my stock tubes may be nearing end-of-life. At a guess, I must be getting up to the mid-high hundreds of hours.
Richard, are you using the BHK preamp? If so, does that have a counter? If so, I imagine you are putting them both into standby, use that counter.
I wonder if anyone has made a clock that could be tied into a tube component or that could easily be used as part of the turn on and standby, might be a money maker.
If I see one on the market in a few months, I want a piece of the action. I sure could use the money.
My preamp doesn’t have a counter either, and I use it on average 18 hours a day. I use the system for TV too. My preamp uses current production tubes, so I just change them once a year. It is the big power tubes that generally have a shorter life span than the 9 pin tubes we use on preamps, or in the first or second stage of a power amp, depending on how hard they are driven. My previous preamp used 6CG7/6FQ7, I ran those 24/7. My 6H30s are rated for 10,000 hours, it will be interesting what BHK has to say about tube life in his products.
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https://www.youtube.com/watch?v=qoDg5j02LiQ
No counter on the BHK Pre.
At 10:15 Arnie Nudel suggests replacing the tubes every year, assuming normal use. In the pre-amp and the amplifiers the stand-by mode bypasses the tubes. You will get a longer life-span than leaving the devices on all the time… Still 12-18 months seems reasonable.
No mention of #hrs though.
There is a counter on the Pre…I was at 1280 hours with the stock tubes and replaced them with new Golden Lion’s. The count is over 200 hours now on the new tubes.
Counter on the pre - do you mind letting me know where it is. I can’t remember seeing one.