Electro Harmonix EL 34’s

I hadn’t purchased a new matched quad of EL34’s in probably like in 15 years and was using a mix of tubes. I saw the EH EL34’s for $37 for a matched quad. At that price I didn’t have anything to lose. I installed and biased them (39 mV on a 1996 Jolida 302).

They were fine at first but after two weeks or so became very noisy, that rattling metallic sound. It seemed that whenever that happened the bias was out by a little, 1.5 mV or so. I’m curious why tubes slightly out of bias create so much noise. Is this a characteristic of cheap tubes? Tubes sound pretty good right now after 3 months.

 

Buying cheap tubes from an unknown seller is always a gamble, and not recommended. Buy your tubes from a reputable seller that tests and matches them properly. You'll get years out of a quad, instead of a few months. Drifting bias is not a good sign, especially if you're having to make several adjustments over the first few months.

jeff

 

Which one is the reputable tube seller nowadays?

 

You purchased a of

You purchased a quad of EL tubes for $37. Most internet stores I see are charging at least twice that much. That would be a warning sign to me. Those tubes were probably not up to par. You get what you pay for.

 

I am running a quad of EH 6CA7 (EL34 in a short fat bottle) and they have been in my system longer than 3 months and I have zero microphany. Sounds like you were sold some tired or rejected tubes. Upscale Audio has quad EH EL34 for about 80 bucks. They are usually a tiny bit higher than most, but you can be sure to get good tubes.

 

There are many. I trust Viva Tubes, TubeDepot, The Tube Store, Upscale Audio, and various other sellers.

 

These are from nesstone.com. Electro Harmonix EL34 | 6CA7 | NessTone Tube Sales

 

I buy my new tubes from Jim McShane. He’s a primarily a Genelex/Gold Lion dealer amongst others.
Jim McShane Home Page

 

I am sorry, but uh EH EL34s are pretty rubbish
If you would know how it looks in that Russian factory
Might simply be bad quality