EL34s and ECC83s

[Moritz Rock]

Hi All,

Changing the tubes in a 1980s JCM800 as one has definitely shorted and it's blowing fuses..
The tubes in the amp are still the original Mullard EL34s and the replacement I'm leaning toward is the SED winged C EL34s as I've used them in the past and I like them.
Someone I know also suggested JJ's, but somehow I'm not too convinced as I have no experience with them.
What would be your choice?

Thinking Mullards.. they do sound nice and NOS are not too difficult to find but they are well pricey, perhaps we should replace only the damaged one. ?? The amp is however also used for live and thinking reliability that wouldn't be a smart move IMO.
Also I'm not sure the price difference can be justified at this point. What do you think?

On a different line, the pre amp section has all but one original mullards ECC83s, the odd one is an indian made tube of some sort..
since when do they make valves in india?? :lol:
The previous owner must have changed it and not bothered with a better tube I guess.:headpalm:

Would you replace all the pre amp tubes as well? Or just that cheap one?
replacing that odd one with an NOS Mullard for this would be my "don't know better choice". also so that the pre section is back to where it should be.
What would you use if anything different and why? Any suggestions?
Perhaps there is no need to change the pre valves is there? again, just thinking reliability, as they are sort of old.

Cheers Mo

[Knastratt]

I'd go all the way NOS Mullards. Creamy! How many hours do they have? IIRC the life expectancy of a pre-amp tube is like 10.000 hours.

Cheers - Pär

[Moritz Rock]

I'd go all the way NOS Mullards. Creamy! How many hours do they have? IIRC the life expectancy of a pre-amp tube is like 10.000 hours.

Cheers - Pär

Hey Par,
Are you talking pre or power?
They shouldn't have that many hours as the amp was kept at home since new until we got it, hence my thought of changing the single one..
Perhaps we should replace just the damaged power too. Do you know what the life expectancy of the power ones is by any chance?

and yup CREAMY!!

Cheers Mo

[Knastratt]

Hey Par,
Are you talking pre or power?
They shouldn't have that many hours as the amp was kept at home since new until we got it, hence my thought of changing the single one..
Perhaps we should replace just the damaged power too. Do you know what the life expectancy of the power ones is by any chance?

and yup CREAMY!!

Cheers Mo

Populate them with all Mullards if you can. As we agreed - creamy! :Wink:

It's roughly half the life expectancy! :Cry:

If they're not that used - I'd just replace the blown ones. Be prepared to readjust the bias - as I'm sure you already know.

Cheers - Pär

[Damage, Inc.]

I happen to like the JJ tubes, they're a bit darker than most of the Chinese tubes available today. If they're that old, at least replace all of the power tubes and get your amp biased. If one is on its way out, the others are sure to follow soon and dying tubes like to take out other parts. As expensive as tubes are, they are still cheaper than having to replace a transformer.

[John Eppstein]

Also check the tube socket of the bad tube for burned spots if the amp was blowing fuses. If you see black carbon smudges on the socket it needs to be replaced.

[G. Hoffman]

Also check the tube socket of the bad tube for burned spots if the amp was blowing fuses. If you see black carbon smudges on the socket it needs to be replaced.


Indeed.


I'll also put in a vote for JJ's. I've found them to be as reliable as anything right now.

For the preamp tubes, if they are working I wouldn't replace them, but you might ask a good amp tech to test at least the phase inverter tube, as they carry the highest load and can wear out long before the other preamp tubes.


Gabriel

[John Eppstein]

Look at the "getter" on the tube. That's the blackish silvery spot on the inside of the glass. If it's turning grey the tube is worn out.

[weedywet]

I use the winged c in my hiwatts.

I HEAR that the newest jj are good but I've been unhappy with them in the past and haven't tried again recently

The preamp tubes don't have to be matched so you can replace the one suspect one with either an nos Mullard or just any good ecc83.

[Damage, Inc.]

+1 to weedy on that. Winged C's are superior to Svetlanas, which are really just Electro-Harmonix with a different label.

[Moritz Rock]

Thanks guys!

I will have a chat with a Marshall tech perhaps later on today.
See and confirm whats actually gone.

Cheers

Mo

[otek]

+1 to weedy on that. Winged C's are superior to Svetlanas, which are really just Electro-Harmonix with a different label.

The way I remember things, the Svetlana factory was around way before the resurgence of the Electro Harmonix brand, and were making some very high quality tubes. Maybe the quality has gone down after the New Sensor Corporation acquired the Electro Harmonix name and started rebranding the Svetlana tubes.


otek

[John Eppstein]

The way I remember things, the Svetlana factory was around way before the resurgence of the Electro Harmonix brand, and were making some very high quality tubes. Maybe the quality has gone down after the New Sensor Corporation acquired the Electro Harmonix name and started rebranding the Svetlana tubes.
otek
I could be wrong about this, but I seem to recall reading something about "old Svetlana tubes" and "new Svetlana tubes". Something about differences in both internal construction and the label. Don't remember where I saw it though.......

[Damage, Inc.]

There was a discussion about this awhile back. The short story is, after a lawsuit, New Sensor got the Svetlana name, and the old Svetlana kept the Winged C logo. The currently labeled Svetlanas are just Sovteks.

[hiphopdaddy]

Electro Harmonix makes the best sounding tubes for most applications IMO.

[Dave Perry]

Mullard EL-34's, NOS, are pretty to very spendy, if you can find them. I'm also amazed that Marshalls were coming stock with Mullards that late.

Don't know much about the new tubes, other than the good reputation Svetlana has, but I never tried an old preamp tube that worked for overdrive and distortion like a long plate Mullard. If you want to take the risk on microphonics, you could get one used off eBay from reputable sellers who will confirm that they test strong.

My second choice would be Brimar.