Tube matching

[al newall]

When looking for some 6p14p-ev tubes, some sellers quote different figures for matching. Any of them really meaningful? I need four for the PP amp.

Example one.
Mutual Conductance is:
Tube 1 86
Tube 2 86
Tube 3 85
Tube 4 85

Example two.

Ia S
mA mA/V
1 - 6P14P-EV test results 51.0 13.0
2 - 6P14P-EV test results 51.0 13.0


Example three.
Ia Ig2 S -Ig1
mA mA mA/V uA
1 - 6P14P-EV test results 43.0 4.0 11.0 >0.2
2 - 6P14P-EV test results 43.0 4.0 11.2 >0.2

[Mike H]

I suppose the most meaningful are mu or mA/V, but they're all helpful.

Although IME matched tubes can "drift off" with increasing use.



 

[Dave the bass]

Dunno about anyone else but I'd be inclined to buy 10 for £6.50 and be done with it Al! http://cgi.ebay.co.uk/6n14p-ECC84-6CW7- ... 473wt_1095

DTB

[al newall]

Dave.

I see there was a typo in my post, that led you to think i wanted 6n14p.
I corrected it now. Its 6p14p-ev i'm after.
Not that it matters, i see what you are saying.
There's a price to paid for matching.
Also, because this tube is getting popular now, i'm probably better off just buying a job lot.

I thought matching might help, because i find it a bit of a chore balancing the output tubes for equal current.

[Mike H]

That's the bit I have an issue with. Once had a GEC / Williamson clone running supposedly matched Golden Dragon KT66's with a bias balancing preset. Found I was readjusting it nearly every week.



 

[al newall]

I think part of my problem was not giving the amp sufficient warm up time before setting up.
Trouble is there are 6 hot el84s upside down, directing all their heat at a wooden top plate. It worries me a bit.

Maybe i should think about some removable panels on the top to allow access to the CCS. But what a mither.

[Mike H]

I would think the EL84's find it a touch on the balmy side as well

Hung upside down by the pins eh?