bottle size on valves

[electo]

hi

thanks for all your help ian will get some kt88 and give it a try

the YAQIN - MC-10L is a great amp lows mods and highs sound good to me

had a couple of problems with it

one of the el34 had an internal short on it the anode plate started glowing red

the other is the mains tx get a bit warm but sorted that with a auto tx
the voltages were a bit high to heaters were running at 6.7volts

i have changed all the chinsse valves to
russan 6n1p
Electro-Harmonix EL34

will try the chinsse one when my replacments come

hope thats some help

and thanks again
mick

[Richard]

Hi Mick

Re the voltage, have you checked to see if there are other tappings you can use on the mains TX? Despite the EU using 230V I found Consonance had provided useful old-style 220V and 240V tappings on an amp I had. It arrived set for 220V and changing it dropped the voltages 10%.

KT88 or 6550 will need a bit more bias. If it's cathode bias try 560R instead of 470R for example. If grid biased check the voltages to keep it within the plate limit and try a few bias settings as you fancy. I've swapped these types around a bit and notice that most EL34s I've used will stand their 25W plate rating OK but most modern KT88/6550 start to get red spots around 35W rather than typical 42W rating so check in a dark room.

Rich

[Shian7]

Interesting looking amp, though it looks like KT88's might be a bit of a tight sqeeze?
I have four spare Svetlana's going cheap if you're interested?

Mike.