What is the "best" of the 5881 Tubes.

I like the old stock Tung-Sol 5881's.

That being said, I've not tested that tube type in several years.

The only 5881's I heard were Sovtek's so I can't judge. However, somewhere I read that your amp would take 6l6gc's. If that is so I would recommend the SED 6l6gc. Its a great tube, especially thru the mid range.

Tubby:

Check out this thread:

http://forum.audiogon.com/cgi-bin/fr.pl?htech&1143225993&read&keyw&zzonix

Before you touch the 5881 tubes (which are basically the military version of the 6L6) in your new Onix SP3, do yourself a favor and install a pair of the Groove Tubes 12AX7-M "Mullard Reissues." You'll find the bass to better defined and the mids livelier without giving anything up in terms of detail and speed. The Chinese stock 5881s are decent, and you can get more mileage out of changing the 12AX7 preamp tubes.

If you have the itch to change the four power tubes, get a matched quad of the SED "Flying C" 6L6GC tubes, and adjust the bias of the tubes accordingly.

Thanks for all info. .... Valuable and appreciated.

I didn't find anyone that had any of the GT 12ax7M tubes in stock (even Groove Tube is back ordered). I did try a pair of Sovtek 12ax7WB's (that I purchased from a music store close by). "BIG" difference (lower/tighter bottom and way more open). I'm getting the feeling that these ONIX SP-3's are VERY-VERY tube sensitive. What a plus !! I have had a few amps that "tube rolling" did just about nothing at all for them. Pleasant surprize indeed.
I will take your advise on the SED 6l6's as soon as I get a new CD player in (one expence after another, isn't it). "TubeDepot.com" has the "Cryo" SED-6L6GC's for about 120.00 (a Quad). I'm thinking seriously about doing that. Haven't tried the Cryo tubes before but have heard some good things.
Have you played around with the 6dj8/6922's at all yet or the 12AU7's ? I would think that the 12AU7's would not have too much effect ( not by my experiences anyway) but a NOS (or better than "stock") set of 6DJ8s might... I don't want to roll all the tubes at once but I am a bit anxious to hear "all" of this "little jewel" of an amp.

Tubby

In a short answer to my own question, I dropped in a pair of NOS GE 6dj8 (6922)'s in the SP-3 and found a slight but very distinct difference. The GE's (similar in sound to the Philips imho) brought out a more "single ended" immediacy with a tad more "forward" presentation. The images are a bit more localized and a bit more transparent. Not whole bunch better, but a little. Combined w/ the 12ax7wb change, it is a lot. I'm sure that cost was a factor in selecting the stock tubes for the SP-3, but in all fairness, they did choose some musical ones. The stock tubes are very open and non-fatiguing, but they are in need of a bit of speed and texture (again imho).

Tubby