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If you were a tube preamplifier manufacturer

We all know NOS tube prices are increasing and getting hard to be obtained day by day,there are several new production power tubes accepted fine performer such as Gold Lion Reissue KT88 and KT66,Shuguang KT88 SC, EH 6CA7,JJ KT77, etc.. among the audiophiles.
If you were a tube preamplifier manufacturer,which type and brand preamp tube you would choose from the new production tubes and why?,considering
its linearity,frequencies band from top to bottom, noise and microphonic clearness ,dynamic and rich midrange spectrum,etc.. ( I find some tubes are noisy or microphonic some has great top end but loose the bass region or just the opposite ...)
Is there any new production preamplifier tube being great performer like the new production power tubes mentioned above?
Thanks
ben
mrtennis
3,295 posts
 
you can design tube circuits so that they are relatively insensitive to changes in tube manufacturers.

i would prefer to allow for variation in sound from changes in tubes. i would not use any current tube in my circuit. sorry, i would insist on using a nos tube. i would use a 6cg7 or two in the line section and a 5ar4 as the rectifier.
atmasphere's avatar
atmasphere
12,099 posts
 
As a manufacturer, you have to consider the lifespan of the product itself. Any decently built amp or preamp is going to last at least 20 years. At the end of that time, where are you going to find the tubes? One thing is certain- if you built the initial design to only work with a certain NOS tube from the get go, you have saddled the customer with a curse. At the end of 20 years, how common is an NOS type going to be if it was only available NOS 20 years earlier??

Of course you cannot predict what conditions are going to exist in the tube market 20 years in advance! But its a good bet that a tube that is not in production now is going to be a lot harder to find in 20 years.

IMO it is unethical to design a tube product that only works with NOS tubes.
ben OP
66 posts
 
Thanks a lot for your valuable opinions, I could filter three tubes from your inputs so far,
EAT ECC803S
EAT ECC88
JJ 6922
mrtennis
3,295 posts
 
hi ralph

designing a preamp using a nos 12 ax7, e.g. is ethically neutral. obviously, the preamp would "work" with any 12ax7, but, would presumably sound different.

it is possible that using tubes currently in production, could still create performance differences as a result of variation in manufacture. there is no guarantee that the performance of a preamp is a "constant", from day to day.

so long as the buyer is aware of all of the facts about tube sonics and tube availability, the buyer can make an intelligent purchasing decision.
atmasphere's avatar
atmasphere
12,099 posts
 
Mrtennis, correct. I personally don't use the 12AX7 because you can't get much bandwidth (the 12AX7 trades off bandwidth for gain), which is essential to getting phase relationships right. So if I need high gain, I use the 12AT7; you can easily get bandwidth out to 200KHz with that tube.

To get day to day consistency, the key is regulation, not the tubes. Tubes generally degrade slowly- over months, not days (unless there is a gross manufacturing defect), but day-to-day issues are usually something else- often the AC power. Good regulation will take care of that.
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