Replacing my Sovtek EL84s

Hi Folks,

The stock Sovtek EL84s on my Fender Blues Junior finally died today. The amp is barely 12 months old. The envelopes on both tubes have developed a crack near the base. Why's that? Am I running them too hot?

Anyway, I've opted to replace them with a matched pair of Harma EL84/E84L tubes from Watford Valves: http://www.watfordvalves.com/product_detail.asp?id=878. They seem to be a good price. Let's hope they are a good buy.

Does anyone here have any recommendations for EL84s?

Thanks.

Bill

JJ's are pretty good, and I've had good experience with Mesa's too.

I have had bad experience with Sovtek tubes. I recently bought a brand new amp with them in it. One of them had a bad rattle (never good) and red-plated within a week which killed it. The tubes were brand new. You read a lot about current production tubes and how they aren't very well made, I guess it's true. EL84s don't seem to be the hardiest of valves out there, but I love the sound they make.

I've been reading up on Blues Juniors over the last few months, one thing I have run across is the so-call billm mod to these amps. According to the article linked below it says that the Blues Junior is biased too hot. I don't know the validity of the claim, but from what you described with the tubes I guess that is possibly the case.

http://home.comcast.net/~machrone/bjrinfo.htm

I'm still interested in learning about the Blues Junior, so other comments are welcome.

Kit

I've been reading up on Blues Juniors over the last few months, one thing I have run across is the so-call billm mod to these amps. According to the article linked below it says that the Blues Junior is biased too hot. I don't know the validity of the claim, but from what you described with the tubes I guess that is possibly the case.

http://home.comcast.net/~machrone/bjrinfo.htm

I'm still interested in learning about the Blues Junior, so other comments are welcome.

Kit

Thanks Kit.

Yep, I've read quite a bit about the BillM mods too. I guess the hot bias could be the reason for the cracked EL84s. I'm keen to have some of the mods done to my Blues Junior, but I'm just a little unsure about doing the mods myself. My Blues Junior was built in 2003 (according to a label on the circuit board). It's the cream circuit board type. It's stock and off-the-shelf. I'm not a gigging player. It stays at home and never gets moved anywhere. The sound is ok for me. I have a Fender G-DEC too and really prefer the tube tones of the Blues Junior, but not sure I'm really getting the maximum tone from it. I'm still experimenting with settings, etc. Maybe I was driving the EL84s too hard and that's why they failed. It was a good price for me. I'm no expert on amps, but it does ok for me. I'm sure others here will have differing opinions.

Bill

P.S. Maybe someone here can give me an opinion on replacing the spring-loaded plate which sits beneath the EL84s? It seems to me that the metal plate and springs put a lots of strain on the tubes. Is it really necessary to replace the plate? As I've said above, I never move the amp. So, surely the plate isn't that important? I had to really wiggle and pull the tubes to remove them. They aren't likely to just drop out, are they? Thanks.

I've had a Blues Junior since they came out in 1995. It's the old, darker sounding green board model. I've read a bit about the BillM mods, but IMHO if you want to change your amp to sound like a Fender Twin, just buy a twin in the first place. The BJ has its own thing going on and I'm quite happy with the sound. I've changed out the speaker for an Eminence Private Jack as the stock speaker is often described as the weak link in the sound. The new cream board designs are much brighter sounding (a better match for darker humbucker guitars) and have an improved reverb circuit.

It's true that they are biased hot, which is what gives them their great sound. The stock Groove Tubes EL84's (re-badged Sovteks) that came with my BJ only lasted about 12 months as well. In hindsight they weren't very good sounding, but I didn't know that until I put in some new tubes. I've run JJ's ever since then. They sound great, don't rattle, and last for absolutely ages. I buy them from Bob at Eurotubes.com. I've also heard good things about Tung Sol tubes and Electro Harmonix. I may try some next time around for a change.

I think if Fender had added a Standby switch to the BJ it would be much kinder to the tubes.

P.S. Maybe someone here can give me an opinion on replacing the spring-loaded plate which sits beneath the EL84s? It seems to me that the metal plate and springs put a lots of strain on the tubes. Is it really necessary to replace the plate? As I've said above, I never move the amp. So, surely the plate isn't that important? I had to really wiggle and pull the tubes to remove them. They aren't likely to just drop out, are they? Thanks.

In my experience the main function of the plate is to stop the tubes rattling. The tubes are such a snug fit in the socket that the plate is definitely not needed to keep the tubes in place. If you don't like the plate, you can also buy soft rubber tube rings which fit around the tubes to stop rattle, but don't place as much stress on them. Eurotubes sells them as well. I have them in a Vox amp and they got rid of any trace of tube rattle.

I've had a Blues Junior since they came out in 1995. It's the old, darker sounding green board model. I've read a bit about the BillM mods, but IMHO if you want to change your amp to sound like a Fender Twin, just buy a twin in the first place. The BJ has its own thing going on and I'm quite happy with the sound. I've changed out the speaker for an Eminence Private Jack as the stock speaker is often described as the weak link in the sound. The new cream board designs are much brighter sounding (a better match for darker humbucker guitars) and have an improved reverb circuit.

It's true that they are biased hot, which is what gives them their great sound. The stock Groove Tubes EL84's (re-badged Sovteks) that came with my BJ only lasted about 12 months as well. In hindsight they weren't very good sounding, but I didn't know that until I put in some new tubes. I've run JJ's ever since then. They sound great, don't rattle, and last for absolutely ages. I buy them from Bob at Eurotubes.com. I've also heard good things about Tung Sol tubes and Electro Harmonix. I may try some next time around for a change.

I think if Fender had added a Standby switch to the BJ it would be much kinder to the tubes. :thumbup:

P.S. Maybe someone here can give me an opinion on replacing the spring-loaded plate which sits beneath the EL84s? It seems to me that the metal plate and springs put a lots of strain on the tubes. Is it really necessary to replace the plate? As I've said above, I never move the amp. So, surely the plate isn't that important? I had to really wiggle and pull the tubes to remove them. They aren't likely to just drop out, are they? Thanks.

In my experience the main function of the plate is to stop the tubes rattling. The tubes are such a snug fit in the socket that the plate is definitely not needed to keep the tubes in place. If you don't like the plate, you can also buy soft rubber tube rings which fit around the tubes to stop rattle, but don't place as much stress on them. Eurotubes sells them as well. I have them in a Vox amp and they got rid of any trace of tube rattle.

Thanks Philby,

This is all really good stuff. I'm looking forward to experimenting with the replacements for the stock Sovtek EL84s in my BJ. I believe the Harma's which I'm buying from Watford Valves are rebadged JJs. Thanks for your views about replacing the plate. I think I'll experiment there too. Maybe leave it off at first. If rattle becomes a problem, I'll check out the tube rings from Eurotubes. More about Harma valves: http://www.watfordvalves.com/products_harma.asp.

Cheers.

Bill

Well, I've ordered a matched pair of Harma EL84/E84L from Watford Valves: http://www.watfordvalves.com/product_detail.asp?id=878
and a matched pair of JJ EL844 from Hot Rox Valves: http://www.hotroxuk.com/jj-electronics-tube-el844-14933-0.html

Let's see how they play. Will report back.

Bill