Tube replacement question that I thought I would share here

[myles_rose]

Below is an email which I answered this morning regarding tube replacement. The player uses a 65 Amps London but this is applicable to many EL84 cathode biased amps out there.

 

Riku see below in the body of your email,

 

From: Riku Karvonen

Subject: 65 London - power tubes?

To: "Myles S. Rose"

Date: Friday, December 18, 2009, 1:22 AM

 

Hello,

 

I was thinking of finally getting spare power tubes for my 2x12 London combo.

 

It is always a good idea to have a spare output set. In the case of a London I would also have a spare 12AX7 for V2 or V3 abd a spare EF86 for V1. Make sure the spares are known good tubes. It is a bit surprising how many "new" tubes have problems right out of the box which are not discovered until one tries to use the tube.

 

I was thinking JJ - as they are pretty easy to get over here, plus they´re quite affordable and get good reviews. My question is - which rating should I get? My local store offers 5 different ratings - from low to high. Which rating would You think sounds best in the London / is the most durable? If You´d like to suggest another brand than JJ it´s fine too, I just want the London to sound the best it can.

 

The JJ is a great EL84, perhaps the current best production tube. The tone and reliability of this tube rivals many NOS tubes. I do not use NOS EL84s in cathode biased amps as tube wear is faster in these amps than in 6L6 or other octal power tube grid biased amps. I have some clients that change their EL84s in as little as ten shows, about 30 hours. That can get a bit expensive.

 

Let me know how this "rating" is determined. What you want might be a medium rating. You want a tube that meets design spec. Not weak, not strong. Folks come up with these "rating systems" so tubes that do not meet spec can be sold rather than tossed in the trash where they belong. There is something basically wrong and substandard with a tube that strays too far from design spec.

 

By the way, I´ve done quite a lot of studio gigs this year - I´ve never had this many, and I feel a part of it is because my gear has never sounded this good before.. The London is unbelieveably versatile, the range of recordings have been from European schlager to contemporary and 60´s soul music to heavy metal and everything has sounded just right with the London.. It´s really a exceptional amp.

 

You will get no argument from me on that Yes, the London is a pretty spectacular piece of work.

 

Best Regards,

 

-Riku Karvonen

 

--

Riku Karvonen

00530 Helsinki

[Caevan O’Shite]

Cool, thanks!