What Tubes Can I Use?

[gtrplayr1976]

No, but you need to set/adjust the grid bias using the bias pot.

I got it figured to 40-45mA? Sound about right for 70-75% 450 plate volts.

[Leo_Gnardo]

I got it figured to 40-45mA? Sound about right for 70-75% 450 plate volts.

I find 30 mA is plenty enough. Maybe 35 at most. All you need is to have the bias current high enough to avoid crossover distortion, which you can easily see with an oscilloscope. If under biased your ears will also detect it as a grungy noise that accompanies an otherwise clean note, sounds like a bad speaker. If your guitar and ears are your only test instruments, pick a low pitched note cleanly, with the tone dialed back to zero.

[gtrplayr1976]

I find 30 mA is plenty enough. Maybe 35 at most. All you need is to have the bias current high enough to avoid crossover distortion, which you can easily see with an oscilloscope. If under biased your ears will also detect it as a grungy noise that accompanies an otherwise clean note, sounds like a bad speaker. If your guitar and ears are your only test instruments, pick a low pitched note cleanly, with the tone dialed back to zero.

I always thought Marshalls liked a higher bias in the 70% range? Fenders more in the 50-60% range?

[The Dude]

I've never subscribed to that,...... with any brands. Your biasing the tubes (circuit) not the amp (brand),..... unless we're talking about some non-standard configuration.

[g1]

A word about JJ's 5881: I'm a big fan! It seems more sturdy than JJ would have you believe. I've been installing them in all sorts of places 6L6GC would usually go. Delivers good power, and in 3 years I haven't had to replace one yet, maybe 100ish of them so far. And no complaints from customers either. I'd recommend not setting bias way high on these. 30 mA plenty enough in amps with a 450-500V B+ and similar screen grid like most Fenders.

The JJ and re-issue 'tung-sol' 5881's are 23W tubes and should be biased accordingly. (26W rating is for triode configuration as per JJ datasheet)
It's unfortunate that when the 5881 moniker was first revived for the russian wafer base tubes, they were robust enough to have 6L6/5881 stamped on them. All the major manufacturers started using them as de-facto 6L6's.

Now that everyone has forgotten what a 5881 was intended to be, they decide to go back to the original spec.

[gtrplayr1976]

I find 30 mA is plenty enough. Maybe 35 at most. All you need is to have the bias current high enough to avoid crossover distortion, which you can easily see with an oscilloscope. If under biased your ears will also detect it as a grungy noise that accompanies an otherwise clean note, sounds like a bad speaker. If your guitar and ears are your only test instruments, pick a low pitched note cleanly, with the tone dialed back to zero.

I will set it there ,and see how it sounds.

[gtrplayr1976]

The JJ and re-issue 'tung-sol' 5881's are 23W tubes and should be biased accordingly. (26W rating is for triode configuration as per JJ datasheet)
It's unfortunate that when the 5881 moniker was first revived for the russian wafer base tubes, they were robust enough to have 6L6/5881 stamped on them. All the major manufacturers started using them as de-facto 6L6's.

Now that everyone has forgotten what a 5881 was intended to be, they decide to go back to the original spec.

I biased them at around 32mA and will see how that sounds. I would like to learn more about power tubes ,and all these specs ,and what can be used in what amps.

[Tone Meister]

The reissue Tung Sol is indeed a 23 watt tube, NOT 26 watts as I said above. Sorry, I got it mixed up with another 5881 type from memory.

Bias them about 32 mA

[Leo_Gnardo]

The JJ and re-issue 'tung-sol' 5881's are 23W tubes and should be biased accordingly. (26W rating is for triode configuration as per JJ datasheet)
It's unfortunate that when the 5881 moniker was first revived for the russian wafer base tubes, they were robust enough to have 6L6/5881 stamped on them. All the major manufacturers started using them as de-facto 6L6's.

Now that everyone has forgotten what a 5881 was intended to be, they decide to go back to the original spec.

And 450V x 0.035A = 15.75W or 68.5% of 23W recommended plate dissipation, Close enough, I hope,for those who must adhere to their interweb-approved 70% rule. I hope they sound all that terrific and a bag of chips for you!

[The Dude]

Maybe it's just dumb luck, but I'll caution against the reissue Tung Sol's. I recently had a customer buy 3 sets of them. Each time they lasted about an hour before failing catastrophically. We finally put in a set of JJ's and no more problems. I wasted hours each time tubes were replaced looking for a problem that wasn't there- thinking I had missed something. The upside was that the customer bought them himself, so I didn't have to deal with returning them for a refund.

[Leo_Gnardo]

The upside was that the customer bought them himself, so I didn't have to deal with returning them for a refund.

Yay! Though it's dismaying to see TS's lack of quality control. Regardless of their claim of "reissue" status which I never took seriously. Except for reuse of the logo painted on the tube and printed on the box. All part of New Sensor's program of fool the customer with specious claims. They're less and less impressive as time goes on, not that I was ever much impressed with their products that bear once proud brand names. "Sovtek" will do fine, don't pretend to be something you're not, New Sensor.

Looks like JJ wins the day and let's hope they can keep it that way.

[gtrplayr1976]

I've had great luck with all JJ power tubes I have bought from Eurotubes. Never had a bad tube.

[Justin Thomas]

I've done enough looking at the guts & comparing to tell me it's the same exact damn tube with a steeper price, when it comes to tubes Sovtek was already making. As to the other "reissue" tubes (like the Mullard 6L6GCs), well, I'm not exactly sure what they're trying to reissue, so... I just chalk it all up to a scam. I'll stick with Sovtek, JJ, & "Made In China" (since Shuggys don't have a "brand" stamped on them).

Justin

[Leo_Gnardo]

"Made In China" (since Shuggys don't have a "brand" stamped on them)

There's "Valve Art" plus a couple others, mostly marketed to our hi fi friends. Let's not forget the 10% - - - no, 25% - - - whups 25% + 10% tariff surcharge. Or is it more now? I can't keep track. Who can???

[Justin Thomas]

Hey Leo,

I meant, the "generic" tubes don't. I've seen Valve Art & such, Audio Glass, Groove Tubes, T.A.D., etc, all on Chinese tubes. What I meant was, when I order "Shuguang" or "Chinese" tubes from say, Tube Depot, they just say "Made In China," usually with just a white sticker attached. I even get em in plain white boxes. JJ & Sovtek at least have their own boxes, too. When I order at the basest level, there's no logo. But when I order JJ & Sovtek, even though they're both relabeled & rebranded by others, they still say Sovtek & JJ. Anything more is a relabel.

Though as Stan had poibted out, the Chinese factories will print anything you want on them if you order a thousand of one type.

Justin