[mike s]

On Saturday, May 14, 2011 1:34:39 AM UTC+1, shawn s wrote:
need two pairs of tubes for my altec amps


I'm curious, do they have to be that type? In the UK we call the equivalent type EL34. Used to be made by Mullard and the like. EL34 is still manufactured in Russia I think and relatively cheap.

[Phil Allison[_3_]]

"mike s"
shawn s wrote:
need two pairs of tubes for my altec amps


I'm curious, do they have to be that type?
In the UK we call the equivalent type EL34.
Used to be made by Mullard and the like.

** The Sylvania 6CA7 is a rather different tube to the EL34 made by Mullard
and others - the structure is different and the electrical characteristics
quite different.

I used a fair number of them in the 1980s for guitar amp repairs - but soon
found they were not happy in 100 watt Marshall amps. The screens would glow
very brightly at full power and the tube soon expired. What I found was
that the screen supply must not exceed 400 volts with them.

In amps that had a screen supply voltage between 360 and 400 volts, the
performance and longevity were both excellent.

Probably the nearest tubes in current production are the " big bottle" 6CA7
by Electro Harmonix and the JJ KT77.


..... Phil

[Big Bad Bob]

On 05/14/11 15:46, mike s so wittily quipped:
On Saturday, May 14, 2011 1:34:39 AM UTC+1, shawn s wrote:
need two pairs of tubes for my altec amps


I'm curious, do they have to be that type? In the UK we call the equivalent type EL34. Used to be made by Mullard and the like. EL34 is still manufactured in Russia I think and relatively cheap.


saw some interesting forum comments 6ca7 vs EL34. Apparently this is a
common issue.

http://www.marshallforum.com/workben...7-vs-el34.html

http://www.thegearpage.net/board/sho...d.php?t=448991

http://vintageamps.com/plexiboard/vi...=27871&start=0

(google search "6ca7 vs el34" showed a LOT of responses, 18000)