Separate names with a comma.
Discussion in 'Glowing Bottle Tube Amp Forum' started by radiocaster, Apr 17, 2016.
Yes, but only buy from reputable sources. Not a cheap tube and notoriously noisy.
Yeah, that was a problem. Heatkit was one that provided detailed info. They specialized in home audio kits but offered a few guitar amps. Haven't seen one in decades - which probably is a good indicator of the quality of the finished product!
Noisy enough that it's a problem for a drive stage? I understand why that's an issue when used as the first gain stage in a combo amp....
What do you mean? A "drive stage" generally means a gain stage. Or do you mean a "driver", aka "phase inverter"? An EF86 pentode is rarely used this way, and microphonic and white noise in the driver would be a huge problem - it's passing signal to the power tubes,a dn any extraneous noises will be directly injected into the power tube input grids.
As a "preamp tube" - i.e.a traditional gain stage - the EF86 has great one IF it's a good tube. But the reason you see them used so rarely nowadays is because of the combination of microphonic and white noise (hiss) many suffer from. But when you find a good one I think it's one of the best gain stage tubes ever made.
Wasn't it "Heathkit ?"
Yeah, I'm old, and remember.
It was Lafayette's brand, which was then an equivalent to Radio Shack.
Noise and is not an issue as a power stage, you have no gain stages afterwards to magnify it. No microphonics either, hard to get a speaker to shake the tube with what it can put out.
By drive, I meant to imply either the "power section" of a micro amp, or the last stage before the power tube in a bigger SE amp.
I assume that signal-to-noise ratio is the issue - and putting a stage of triode gain in front of one would help.....
Yes, obviously that was just a typo.
A power tube can contribute noise, as can a phase inverter. It's not usually as significant as a preamp, but it can still be a problem.
Just ordered one at TubeDepot - who's having a 15% off sale on JJ bottles...
Along time ago I saw a book on making an amp like that, would be interesting to build one.
Why use an expensive tube that you will have a hard, expensive time getting an output transformer for? There are other easy ways to get the job done.