Is it possible to build a guitar preamp with EF89?

[DrFireBottle]

Hey all!
So I saw some amps using EF86 but never saw any using EF89 which are usually radio tubes, so is it possible?

 

[JonSnell Electronic]

It is but they are not best suited to AF.

 

[djgibson51]

Google variable mu pentode to see what you can do with it.

 

[Printer2]

Variable μ (type of pentode), nothing you want to play with. So many other good choices.

 

[thoglette]

Variable μ (type of pentode), nothing you want to play with. So many other good choices.

Fred's Dogzilla would suggest otherwise😀. But compressers are a whole extra world of complication. You could get a neat vibtrato/tremlo effect too.

Note that hum and microphony are widely reported problems with pentode input stages. If you're going multistage, perhaps put the pentode further down the chain?

 

[DrFireBottle]

Looks cool!

Could I modify it and build a recording compressor?

 

[Printer2]

Fred's Dogzilla would suggest otherwise😀. But compressers are a whole extra world of complication.



Note that hum and microphony are widely reported problems with pentode input stages. If you're going multistage, perhaps put the pentode further down the chain?

Yeah, lot of successful designs out there using variable μ pentodes out there. (go ahead, search for them) I actually tried messing around with them and decided if I want a linear amplifier I am going to use a sharp cutoff pentode. If I want to make a compressor there are a few groups that have gone down that road and figured out what works well.