Author Topic: Some numbers on valves?? (Read 2728 times)

LazyNinja · « **on:** February 07, 2007, 09:45:44 PM »

Hi folks,

I'm new to changing power amp valves and I just got some EL34s (svet winged Cs) from watford valves. I ordered a matched quad. When I received them, it had some numbers on the top of the valves and also on the boxes. Two of them read 42/5.8 and the other two 42/8.5.

What do those numbers mean and what does this mean I have to do when installing these tubes? Do I put them side by side in pairs or 2 inside and 2 outside? Thanks.

Twinfan · « **Reply #1 on:** February 07, 2007, 09:47:28 PM »

The numbers mean they're matched pairs.

I think you want one matched pair on the inside, and the other on the outside, of the four valve bases. Someone else will need to confirm that though...

I've got to ask - why didn't you get a fully matched quad? Error at Watford Valves? Or is that normal to get two pairs?

Twinfan · « **Reply #2 on:** February 07, 2007, 10:03:28 PM »

Info from Marshall's website:

Quote

The valve line-up in a 100 watt amplifier is shown in pairs - 2 on the left (1 & 2) and 2 on the right (3 & 4).

When replacing power valves in matched pairs, replace (1 & 4) and (2 & 3).

LazyNinja · « **Reply #3 on:** February 07, 2007, 10:07:45 PM »

thanks. so I need to pair the outsides and the insides huh?

What do those numbers actually mean though? What parameters are the figures for??

LazyNinja · « **Reply #4 on:** February 07, 2007, 10:13:13 PM »

Quote from: Twinfan

I've got to ask - why didn't you get a fully matched quad? Error at Watford Valves? Or is that normal to get two pairs?

Just checked each one again and youre right they are all matched in numbers after all! The figures on the boxes were wrong but on the valves they are all the same. Strange. I guess its their mistake like you said, 5.8 can look like 8.5 upside down I guess.

Well, this eliminates the positioning question I had but I still want to know what they all mean...

HTH AMPS · « **Reply #5 on:** February 07, 2007, 11:01:14 PM »

this is a long shot, but why don't you ask Watford Valves what the numbers mean :roll:

it will be to do with whatever system WV use to match their valves - the first number is most likely the current drawn at the plate voltage used to match them. the second is anyone's guess - seems too low to be transductance.

:twisted:

LazyNinja · « **Reply #6 on:** February 07, 2007, 11:18:04 PM »

yeah I did that yesterday but didnt get any reply. Im too impatient! :D

LazyNinja · « **Reply #7 on:** February 08, 2007, 07:48:21 PM »

Hi, I was about to install the new valves and then I noticed that the svets have 7 pins while the Rubys have 8. Theyre both EL34s. Is it ok to plug the new tubes in?

HTH AMPS · « **Reply #8 on:** February 08, 2007, 09:40:24 PM »

Quote from: LazyNinja

Hi, I was about to install the new valves and then I noticed that the svets have 7 pins while the Rubys have 8. Theyre both EL34s. Is it ok to plug the new tubes in?

some EL34s don't have pin 6 installed at all, some do. it makes no difference since it's not internaly connected to the valve. go ahead and plug 'em in providing you rebias the amp.

:twisted: