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Re: What do you consider as an excellent tube for preamp/drivers

Posted by Adrian on November 4, 2000 at 05:06:45

In Reply to: Re: What do you consider as an excellent tube for preamp/drivers posted by Frank on November 4, 2000 at 04:17:54:

A lot depends on the circuit. An excellent tube used in the wrong circuit will sound worse than an average tube used in an excellent circuit. Those tubes mentioned all have very high transconductance and low plate resistance (hence fairly high Mu). The 6H30p beloved by our very own Victor is another example, but the BAT brochure claiming this tube to be a super tube and a Russian military secret etc. etc. is a bit far fetched, as the WE437A was introduced in 1968 and still is ahead of the 6H30p in these important parameters. The only difference is, the 6H30p is still in production in Russia, whereas the WE437A is out of production and getting more expensive. These are all frame grid tubes, and as such, are cousins of the familiar 6DJ8. They were designed for UHF applications.
The reason for not seeing these tubes in your average commercial preamp? Have you been able to find a stash of these tubes? How do manufacturers (other than brave ones like our very own Mr. Rankin) find enough stock to ensure continous product availability, and for after sales services? Kevin has been given a hard enough time for reserving his stash of 6DJ8s for customers who bought preamps from him. Imagine if these same guys now want a spare set of 437A!
With a Mu of 45 and an Ra of 1000 Ohms, the 437A can be used for a single stage preamp. Nice simple circuit, and very linear. Highly recommended for DIY projects (no, I am not selling any of my 437A or EC8020, but you can have some 417A).

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