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6L6 vs. 5881 vs. 6550 tubes- any opinions?

7/18/1998 1:23 PM
Steve A.
6L6 vs. 5881 vs. 6550 tubes- any opinions?
    So how do these tubes compare to each other in terms of sound and response in a BF'd Fender amp and in a 5F6A clone amp? Other than resetting the bias are there any other modifications that need to be done?  
    Any opinions on the differences between different imported 6L6's: Sovtek vs. Svetlana vs. chinese? Any recommendations for 5881's? Any reason to use 6550's instead?  
    I've experimented around with different preamp tubes, but matched pairs of output tubes can become very expen$ive...  
Steve Ahola
7/18/1998 2:12 PM

> Any reason to use 6550's instead? <  
Well, if you're afraid that you'll get too much life out of your filament winding, you could always put in the 6550's.  
I like the Svetlana's, which are louder than the Sovtek 5881WXT. However, the 5881WXT is better for a blues tone amp IMHO. They are a little mushier, breakup lower, and just a little warmer, tho not much.  
I've also been using the 7581Phillips and getting a great clean sound with nice bottom.
7/18/1998 8:59 PM

Steve, I like the sevtlanas [6L6s]the best, I've used the 5881 sovtek and the are pretty good too,and have been very reliable.but since I've tried the sevtlanas thats what I have been putting in all the amps I work on.As far as the 6550s I like to use the 6L6s because that is what [fenders were designed for.but if you like the cleaner sound you can use them, just chek your bias.[Richie]
7/18/1998 11:21 PM

Steve, I certainly can't give you much in the wat of technical info, but my (somewhat humble) opinion is that the Svetlanas are the way to go. I've been playing guitar since around '64, and a few years ago I got turned onto Sovtek amps by a friend who has worked as a sound tech for several bands (totally non-famous and very famous). I got a 4100 version of the JCM 900 early last year, partly because I liked the sound of the Sovtek 5881s so much. I recently had them replaced with Svetlanas, and the difference is mind-blowing. the clean channel is still the cleanest Marshall ever, but with harmonics that weren't there before. The high-gain channel is in another world than it was, as high-gain as you could want a Marshall to be and still smooth with great harmonic overtones. I can't overstate my opinion of Svetlana tubes. Since my father was a mighty muckamuck in the military/space R&D through the '50s, '60s and '70s I learned a lot about Russian military technology, and they had tubes down better than anyone in the world. The Svetlana plant was made for tube production for applications where failure was unacceptable.  
7/19/1998 1:44 AM
Steve A.

    Are the Svetlana tubes you recommend 6L6GC's or 5881's?  
Steve Ahola
7/19/1998 1:06 PM
I've heard of using both 6l6's and 5881's in a 5f6a before, but I did not realize you could use 6550's or 7581's. Are both these types safe to use in that amp? Now that I think about it, aren't 7581's a high power 6l6/5881s? Can anyone offer any insight as to how these tubes would affect tone. Joe
7/19/1998 8:16 PM

Anonymous: RMS/EIA designations are: 5881 = 6L6GWB, 7581 = 6L6GWC. But, with all the craziness, mismatching numbers, and outright semi-fraud, anything goes.  
PS: The NOS Phillips 7581s are really great tubes, they sound great, last long, and even look good when you examine the insides.
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