5881=6L6

[triodal]

Is this correct?I got a Mesa 295.The inner was supposed to be 6L6 tubes.But the previous owner changed it to 5881 tubes instead.Safe?

 

[Guitarzan]

You're good. No harm is being done to your amp. Read This page for some clarification.

 

[stokes]

That article says nothing about the tube ratings.He is only offering, this is the best or this is better than...If you look at a tube manual you will see a 5881's design max calls for 360 max plate volts and 19watt max output.The 6L6GC,which is todays standard 6L6 used by amp makers,can take a max of 500 plate volts and put out 30watts max.This author is only talking about Sovtek,and I will say I have little experience with Sovtek 5881's,so if they are designed to the higher standards of the 6L6GC then they are not true 5881's.Since Triodal didnt mention Sovtek I would have to say,if he is talking about a true 5881 and the amp is designed for a 6L6GC then it is not safe to use the 5881's.I dont have a schem for the Mesa 295,but if it has the typical high plate voltages like most Mesa's,then a true 5881 will not hold up.

 

[triodal]

Hi guys,yup its sovtek 5881 tubes..So right now the amp running in EL34s & 5881s..I thought the 5881 were the same 6L6 family?

 

[stokes]

They are the same "family" but if you check the tube data there are many differences between all the 6L6's,as I pointed out in my last post.I cant say for sure about the Sovtek 5881's but if they are true 5881's,they cannot take the voltage or the plate disipation in an amp designed for the 6l6GC.The only thing the "same" between these two tubes is the pin out.There are a lot of tubes with the same pin out but they arent necessarily interchangeable.

 

[earachemyeye]

I've had Sovtek 5881's in my Nomad for about a year now. They work fine. In fact I prefer them to the 6l6's that came stock in it. They've smoothed out the overall harshness of the gain channels. :wink:

 

[stokes]

Then they are not true 5881's.Even that article that Guitarzan posted said they are relabeled Russian tubes of some sort.

 

[Timbre Wolf]

Just another confirmation of what Stokes said: Sovtek "5881" are okay to sub for 6L6GC in your Boogie, but not NOS true 5881, which are rated for a lower voltage and may not last long in a 6L6GC-designed amp.

Sovtek really screwed things up by falsely labeling those "5881" in my opinion.

- Thom

 

[earachemyeye]

Well I certainly won't contend with you gents. They definately sound different. From the article they are spec'd out to different tolerances (closer) as in built for military applications. Could this be it? My experience has been they required me to turn up to get an equal amount of volume (about 1/8 of the dial) in comparison to the stock 6L's and also they tapered the highs off some (what I was looking for) and smoothed out the gain. I hope I can get the same results when I retube. Thanks for sharing your knowledge guys.

 

[stokes]

earache,if they work for you,thats great.Just dont try using a NOS Tung-sol 5881 in there,it wont last.

 

[earachemyeye]

Gotcha Stokes, thanks for the heads up.

 

[Boogieman]

Well I certainly won't contend with you gents. They definately sound different. From the article they are spec'd out to different tolerances (closer) as in built for military applications. Could this be it? My experience has been they required me to turn up to get an equal amount of volume (about 1/8 of the dial) in comparison to the stock 6L's and also they tapered the highs off some (what I was looking for) and smoothed out the gain. I hope I can get the same results when I retube. Thanks for sharing your knowledge guys.

Yep, this is what I reckon when I put a pair of Sovtek 5881's into my Mk.II. They cut off some of the high frequencies and I had to turn the amp's master volume further up to get the same volume projection.

I have a few NOS Tung-Sol 5881's and my tech told me NOT to use them on old Boogie amps.

 

[stokes]

Boogieman,your tech is 100% right on that advice.Some years ago I had a bunch of Tung-sol 5881's,I tested them and matched them up and decided to see how much they would take so I took a pair that tested like new and appeared to be and put them in my MKIIC+,and played them an hour or so a day,the first hour the flashing turned brown,two days later the tubes were cooked.
"I have a few NOS Tung-Sol 5881's and my tech told me NOT to use them on old Boogie amps."I would go one step further and say not to put them in any new amp designed for 6L6GC's.A 5881 is designed for about 360v's on the plate.

 

[Boogieman]

Wow, fried in two days. :shock:

 

[stokes]

Three days actually,about 3-4 hours of hard use.

 

[LUCRETIA]

i used sovtek 5881 wxt on my simul 395 recently..

after a while the cathodes fuse blows..could the 5881 wxt cause the problem or i have defective tubes and internal bias problem?

 

[stokes]

If your cathode fuse is blowing,I would suspect the tubes are drawing too much current due to improper bias,assuming there are no other problems with the amp.