KT88s

[mhuss]

We've been having an above average failure rate with the KT88s in our 200 watt amps. JJs failed a lot. Gold Lions are better, but we're still getting failures. Can anyone here recommend a sturdy KT88 that can stand up to guitar amp abuse at 700 plate /400 screen volts?

--mark

[PeanutNore]

It's too bad they don't make winged C's anymore.

[Jazz P Bass]

How are the tubes failing?

Plate to heater?

Screen grid?

[J M Fahey]

Ouch !!!!

Thanks for asking but since they are little used, probably you have far more practical experience with them than any of us, since you use them in series production.

Not many suppliers anyway, and no matter what's printed on the glass, doubt any are up to par with original ones, so I guess the only way is to buy a few from different suppliers and test them.

Then you tell us

Just mumbling: does Ruby Tubes offer them?

They have consistently been trusty suppliers and back what they sell.

I'm dissing nobody, far from that, but in general have not found JJ the high consistent quality one would have expected from an European supplier.

Hope you solve it

[pdf64]

Good suggestion!
They offer a Ruby branded JJ and this KT88STR | Magic Parts Co.
Any ideas on its origin?

[Chuck H]

I can't say about KT88's, but my experience with JJ EL34's has been that they don't handle being pushed at high-ish plate volts. And I'm not talking near max. 475Vp produced a plate to heater short in two different pairs the moment the tubes were clipping. I gave up on JJ's and tried Ruby's. I've had one microphonic tube but none have blown up yet. Never tried the Gold Lions. Aren't they Chinese? In case that's been your reason for not trying the Ruby offerings. I know Shuguang makes KT88's so I expect Ruby tests, matches and sells them. They have a warranty you can actually use so there's nothing to lose.

[Justin Thomas]

Gold Lion = RI Genelex = Reflektor = EH/Sovtek/Tung Sol RI/Mullard RI. Basically, if it's a vintage brand that's been resurrected, it's Reflektor/Sovtek. Given my (admittedly very limited) experience with EH, I'd give em a shot but expect a short when cranked. Now, Sovtek 5881WXTs & preamp tubes? No issues if tested first. I personally am moving to Chinese pre tubes/Scavenged Old Stock. But I don't have a line to outfit, so I can get by with that. Try the Rubies - isn't it kinda the last option? Or NOS =C=, if you can get a lot...

Justin

Hmmmm... 8 6L6GCs... It's possible, I reckon.

[g1]

Hmmmm... 8 6L6GCs... It's possible, I reckon.

Traynor YBA300 uses 12 x 6L6's.

[Jazz P Bass]

i don't know what perceived sonic difference there is between a 6L6 & a KT88 but I have successfully used Sovtek 6L6WXT tubes in 700/400 volt amps.

[Leo_Gnardo]

Good suggestion!
They offer a Ruby branded JJ and this KT88STR | Magic Parts Co.
Any ideas on its origin?

Ruby's KT88STR is made in China, I presume Shuguang.

[Justin Thomas]

Try those 5881WXTs - they have a good rep.for taking abuse. And they're dirt cheap!

Justin

[g1]

KT88's are a (supposedly) 42W tube. So if he goes with 6L6 his 200W amp will likely be down on power.

[J M Fahey]

There are only a few actual manufacturers left, all others are rebranders, but Ruby Tubes has worked hard to skim the best and as insurance back what they offer, so I guess they deserve being recommended and used.

As a side note, I love their no hype policy.

Labels?
They mean NOTHING.

[Gregg]

Can anyone here recommend a sturdy KT88 that can stand up to guitar amp abuse at 700 plate /400 screen volts?

Maybe lowering those voltages would be a good idea?
I made a 6xKT88 amp several years ago and used JJs. The guy changed tube only once since then but I guess it depends on the batch as well.

[J M Fahey]

I think our friend Mhuss is building Hiwatt 200W clones with 4 x KT88 and so is stuck with matching original schematics in every detail, obviously including tube complement, supply voltage, etc.

In that case, I guess Ruby Tubes is the safest bet, by far.

Beyond who actually makes them, Ruby tests and selects the best available.

Different to new designs where you have more flexibility.