Questions about tubes and fuses

Daddydex · September 4th, 2007, 10:50 PM

I am in the process of getting my Carvin amp up and running. This amp has four 6L6GC power tubes. I have heard 5881WXT's described as a 6L6 variant. Does this mean I can substitute the 5881's for the 6L6's? The speaker comes tomorrow and would like to just get it fired up and start breaking in the speaker before I order new matched tubes. The amp has three working tubes so I was hoping I could just pull the 5881 out of my Blues Deville temporarily.

Also, there is fuse between the chassis and the speaker that is blown and I can't see what kind of fuse it is (my eyesight sucks ). Does anyone have any idea what type of fuse I can use for this application? Can I bypass the fuse?

Thanks in advance.

Dan

Daddydex · September 5th, 2007, 01:47 PM

OK, the fuse issued is solved but I would still like to know about the 5881 for 6L6 substitution.

Does anyone know if I can use a 5881 in place of one 6L6GC temporarily without hurting anything?

Dan

11 Gauge · September 5th, 2007, 02:16 PM

I would proceed with caution.

Modern 5881s (i.e. the 5881WXTs) have nothing to do with the old ones of yore - they are like a "non-industrial strength" 6L6, can't dissipate heat well, and can't tolerate the higher voltages that are typical of most modern 6L6 amps.

What does this mean? They could run just fine. Or - they could run fine for a little while, and then melt. If you're lucky, they will just smoke a screen resistor and pop a fuse. If you are unlucky, your output transformer could be collateral damage.

I remember a lot of those 5881s pooching out in the 90s.

I would wait a few days for some quality 6L6s to show up.

Dacious · September 6th, 2007, 01:30 AM

The Sovtek 5881 is a Russian military tube and to all intents and purposes is interchangeable with modern 6L6s. Many people don't like the tone, although it suits some amps. They will drop a little power compared to a 6L6 because they aren't quite as efficient.

The older 5881 is not rated for 25 watts each, although many would do it easily. Some are big-bottle tubes and won't fit in the tube spacing on a Twin or similar chassis.

Daddydex · September 6th, 2007, 01:36 AM

I gigged with this amp tonight. It worked fine with the 3 original (25 year old) Carvin 6L6's and 1 5881WXT. I will, of course, be in the market for new power tubes. Any suggestions?

Thanks for the help guys.

Dan

September 4th, 2007, 10:50 PM	#1 (permalink)
Daddydex Tele-Afflicted Join Date: Feb 2007 Location: Pennsylvania Posts: 1,584	Questions about tubes and fuses I am in the process of getting my Carvin amp up and running. This amp has four 6L6GC power tubes. I have heard 5881WXT's described as a 6L6 variant. Does this mean I can substitute the 5881's for the 6L6's? The speaker comes tomorrow and would like to just get it fired up and start breaking in the speaker before I order new matched tubes. The amp has three working tubes so I was hoping I could just pull the 5881 out of my Blues Deville temporarily. Also, there is fuse between the chassis and the speaker that is blown and I can't see what kind of fuse it is (my eyesight sucks ). Does anyone have any idea what type of fuse I can use for this application? Can I bypass the fuse? Thanks in advance. Dan __________________ Teles are like Mr. Potato head

September 5th, 2007, 01:47 PM	#2 (permalink)
Daddydex Tele-Afflicted Join Date: Feb 2007 Location: Pennsylvania Posts: 1,584	OK, the fuse issued is solved but I would still like to know about the 5881 for 6L6 substitution. Does anyone know if I can use a 5881 in place of one 6L6GC temporarily without hurting anything? Dan __________________ Teles are like Mr. Potato head

September 5th, 2007, 02:16 PM	#3 (permalink)
11 Gauge Friend of Leo's Join Date: Mar 2003 Location: The East Coast Posts: 2,898 10 Photos	I would proceed with caution. Modern 5881s (i.e. the 5881WXTs) have nothing to do with the old ones of yore - they are like a "non-industrial strength" 6L6, can't dissipate heat well, and can't tolerate the higher voltages that are typical of most modern 6L6 amps. What does this mean? They could run just fine. Or - they could run fine for a little while, and then melt. If you're lucky, they will just smoke a screen resistor and pop a fuse. If you are unlucky, your output transformer could be collateral damage. I remember a lot of those 5881s pooching out in the 90s. I would wait a few days for some quality 6L6s to show up. __________________

September 6th, 2007, 01:30 AM	#4 (permalink)
Dacious Friend of Leo's Join Date: Mar 2003 Location: Godzone Posts: 2,612 35 Photos	The Sovtek 5881 is a Russian military tube and to all intents and purposes is interchangeable with modern 6L6s. Many people don't like the tone, although it suits some amps. They will drop a little power compared to a 6L6 because they aren't quite as efficient. The older 5881 is not rated for 25 watts each, although many would do it easily. Some are big-bottle tubes and won't fit in the tube spacing on a Twin or similar chassis. __________________ My other Telecaster is a Thinline The Tele Bible, Ch 1, v 10 Love thy Telecaster, covet not thy neighbour's Strat!

September 6th, 2007, 01:36 AM	#5 (permalink)
Daddydex Tele-Afflicted Join Date: Feb 2007 Location: Pennsylvania Posts: 1,584	I gigged with this amp tonight. It worked fine with the 3 original (25 year old) Carvin 6L6's and 1 5881WXT. I will, of course, be in the market for new power tubes. Any suggestions? Thanks for the help guys. Dan __________________ Teles are like Mr. Potato head