amps, tubes, and minor changes...

[JoeyHarley]

i've got a 1991 fender DRRI that came with 6L6's in it. Never really thought about it until i started reading here a bit, and learned that this is a fairly common mod to DR's which are supposed to come with 6V6's in 'em.

so, how did somebody figure out that you could do that? and how do you figure out what adjustments need to be made to the amp to do it safely?

the reason i ask is i recently got a jetcity jca20H head. it sounds great, but alot of cats have been telling me it'll sound better if i retube it. which got me thinking....can i drop 6L6's in it, or some other higher powered tube? how do i go about figuring this out?

[SatelliteAmps]

THe way people figured this is that the tubes drop right in. The issue is whether the power transformer can supply enough current, and whether the output transformer can take it. It's not just that you can convert any amp this way or this easily. The best way to find out would be to contact someone at JetCity and ask them, or see if you can find out the specs of the transformers.

[JoeyHarley]

thanks, sat! i've tried contacting them to find out what tubes come in it (not in the manual?) and so far haven't heard back. anybody know what tubes have the same sockets? i know 6L6's and V6's are the same, what others?

[SatelliteAmps]

Most of the commonly discussed octal based tubes. 5881, 6y6, 6550, kt66, kt88, 6l6, and any of the variants. EL34's (and KT77s) can sometimes also work (depends on how one pin is wired or not).

[JoeyHarley]

sweet, thanks, adam!

how do i find out what the minimum current needed is and whether or not the output transformer can handle it?

[SatelliteAmps]

You can find the info from any tube manual (tube data sheets are available all over the place online.) Look up what the filament current requirements are. They are usually labeled Ih, and it is a unit of amps (A).

[JoeyHarley]

nice, thank you! now if i can just get JC to give up the info 8)

[phsyconoodler]

Went to the Jetcity site and looked at the JCA20 head.It uses a pair of EL84's which are 9 pin tubes,the same as the preamp tubes.
You cannot swap tube types in that amp.The best you can do is use different MAKES of EL84's and preamp tubes.
Depends what the amp comes with stock.