MK III power tube question (7027a?)

[HelpingFriendly]

Hello again. I was wondering if anyone here has tried using 7027a tubes in their boogies? Particularly the Mark III? I know there are 2 extra pins on the 7027a's, but I need to know if the only way to make it work is to snip the extra pins? Or if it is not necessary to snip. The tubes physically fit so that's not an issue. Any input is appreciated.

 

[stokes]

The tubes will work.In a 7027 the screen is connected to pin1 as well as pin4 and the control grid is connected to pin6 as well as pin5.In the normal 6L6 pin1 and pin6 is not used.Just check that those 2 pins have nothing mounted on the socket to them,people sometimes use the empty sockets to "hang" a part.You will also have to re bias for the 7027's.I've been using them in my MKIIC+ for years.

 

[HelpingFriendly]

Thanks for the reply. So let me see if I have this right. I need to make sure that pin 1 and 6 have nothing attached to it? My amp was modded with a triode/Pentode switch so there could be somthing connected on pin 1 but that is just so Pentode will work (not 100% though) .. would that matter? I know pin 1 is empty. You think I need to snip pin 1 or you think it will be ok?

Also, did you notice any difference in tone with the 7027a compared to 6l6?

 

[stokes]

Since you know there have been mods done to the amp,I would say you should open the chassis and make sure nothing is connected to the sockets at pin1 and pin6.You will need to re-bias,so you will need to have an adjustable bias pot installed,so even if you use the 6L6's you will see an improvement in tone as you can "dial in" the tubes "sweet spot".I am,and have been,using NOS tubes for years in my amp.The 7027A is a 35 watt tube,compared to the 30 watt 6L6GC and in general is a more robust,fuller sounding tube.I find the tone is much more complex and much smoother when pushed into break-up.