Class 5 resistor fried (help)

[falkman]

Hey guys!

I've been hanging around anonymously for a while and just soaking up all the knowedge that is available on this forum.
But now my trusty Class 5 has stopped working. First it started cutting out, just like if your cord would be malfunctioning, but then the sound came back. It kept cutting in and out for a while before going silent and smoke started coming out of it. I opened it up but couldn't find what was burning and put it back together and played it for a while before it started cutting out again, and after a while there was smoke again. When I opened it up the second time I saw that R5 had burnt up. It looked like it had burst open.
I have an early version (early 2010), I'm using a Sovtek el84M and I haven't been pushing the amp this much before with this tube. Also the power at my house is weird, there seems to be a lot of power surge at times.

So, anyone got a clue why R5 burned open? Is it the el84M that causing it, I've seen lots of other people having trouble with that tube (to bad because it sounds great!).
Changing R5 is no problem for me but it seems like a waste if there is an underlying problem. I would really appreciate your help on this matter. :)

BR

falkman

[exotl]

Hallo falkman & welcome to the roadhouse!

After a glimpse at the schematic I can hardly imagine anything but the dying EL84 to roast R5, so if it were my amp I would go ahead and replace it together with the tube. On the other hand I'm not an amp technician, so you better wait for some other members to chime in and confirm this.

Cheers

[skinnyj]

I have read that the Sovtek EL84M and this amp don't get along.

It may be tech time.

[falkman]

Thanks for the replies guys! I guess I'll just replace the resistor and get a new tube. Not sure if I'll go for an EL84M again though, loved the tone but don't want this happening again.

Any recomendations for tubes that sounds like the EL84M (less gain)?

/falkman

[Stillhouse]

I just picked up a used C5 combo about a week ago and was looking at tube options. Heard a bunch of owners say the JJ EL844 is a good choice if you're looking for a little less power.

[skinnyj]

I just picked up a used C5 combo about a week ago and was looking at tube options. Heard a bunch of owners say the JJ EL844 is a good choice if you're looking for a little less power.

If I recall, the '844 isn't less power, it just has less headroom, meaning breakup comes earlier. I had one in my C5, but I cracked it while tube rolling, so I didn't get to spend enough time with it to form an opinion.

[Cousin Muely]

I just picked up a used C5 combo about a week ago and was looking at tube options. Heard a bunch of owners say the JJ EL844 is a good choice if you're looking for a little less power.

If I recall, the '844 isn't less power, it just has less headroom, meaning breakup comes earlier. I had one in my C5, but I cracked it while tube rolling, so I didn't get to spend enough time with it to form an opinion.

I have these in my C5s. Yes, breakup does come sooner and although it's not a drastic change there is a drop in volume. They do give a nice crunch but I am considering changing them back out for just regular EL84s. It just goes back to what you want at the moment or the flavor of the month. Good tubes though for a slight reduction in volume and more crunch for playing at home in 5 watt mode.