Which 6L6/5881 valves?

[rockmeister]

Since I can't afford £1000 sadly, for a 4X set of GE USA KT66's,(but if you can, you should get some if your amp will take them because they sound amazing), I'm looking for a set of 6L6/5881's to go in my Leben CS600. The Leben is a tube rollers dream, allowing (by switchable cathode resistor/plate voltage options) any of 6L6, EL34, 5881, KT77, 350B, KT66/88, 6550A etc etc, but the size of some of those is also BIG. Anyway Leben supply the amp with 6L6's installed and I imagine they know a thing or 3.
I have installed some Sophia Electric EL34's which are beautiful sounding, but too big to allow the amp top plate to fit on. Not a prob, except at times I need it on, and anyway was looking for a valve that sounded a bit tighter than the Sophias for those ZZ Top moments.
I have the original Sovtek 6L6's here with around 1000 hours on them. They are reliable as a rhino, but not the world's best sounding valves IME, so, what else? All thoughts most welcome.

 

[toprepairman]

I like the Russian 5881's with the squat valve bases.

 

[antonio66]

Although for a different amp, I was recommended NOS Sylvania 6L6's

 

[rabski]

Usual comments apply: the circuit is what makes the sound, not the valves. However, all else accounted for, there are some generalisations that mostly ring true. Any suggestions are a guess to some extent, unless someone has tried the exact same valves in the exact same amplifier. Also, your comment about size is a bit of a concern, as most of the valves mentioned are larger physically than EL34s

Nevertheless... Out of your list, if you want something to rock a bit harder than EL34s, I'd suggest KT66. IME they're a bit more lively than the others, including 6L6. Also, 6L6 has numerous variants, which are slightly different specs (6L6, 6L6G, 6L6GC, et al.). The amp specs suggest it would run KT88, but not at the ideal load, so it will probably actually get more out of a KT66. The UK GEC KT66 and other early versions would be superb, but are going to be a no-go, based on size, rarity and prices.

I have more experience of KT88, but assuming reasonable similarities between 66s and 88s, quite surprisingly, some of the 'guitar amp' valves are far better that you'd expect. The TAD and Marshall branded KT88s don't sound at all scruffy. Maybe a little 'loose round the edges', but it's a tradeoff. The re-issue Gold Lions are also likely to be very decent, and possibly the best of the lot, apart from NOS stuff.

I'm going to disagree with Henry here, as I have a heap of Sovtek and Tung Sol 5881s and I really don't rate them. They're not bad at all, but IMHO, not the best either.

 

[Ian]

Great thread and responses as I have a Primaluna Prologue 5 in my sights, which takes a similar compliment of valves.
I'll echo what Rabski says re: the Genalex Gold Lion reissues, these are my favorites current production valves.

 

[rockmeister]

I have here already Sovtek 6L6GC's. they are what come with a Leben 600, and fit, cover on. the Sophia 34's are not a standard EL 34 size or shape, and don't fit, but do sound great.
I also have my old Electro Harmonix EL34's as used in the Luxman for maybe 1000 hours. It's valve I like, but hard to compare since I don't much trust 1000 hours even for these.

I'll have a peek at the Gold lions and see what's occurin.

 

[Ian]

l have a peek at the Gold lions and see what's occurin.

Certainly not the cheapest by any means, and going up but..........

 

[bencat]

After a bit of trying I found that these were the most sensible option for KT66 valves with a cost that was not too silly and a quality of the original GEC NOS valve without the body surgery needed to pay for them . I used 6LGC in my Quad II amps and they were a little too warm and rounded in that design . KT66 were the original specified for this amp and worked the best of all in this amp . This version was the nearest I found in sound quality to GEC originals and in my view the difference was so slight that it was not even worth thinking about let alone paying for .

https://www.watfordvalves.com/product_detail.asp?id=5917

 

[JANDL100]

My limited experience with 6L6 valves would not lead me to recommend them if you want to rock out.

I had a CR Developments Romulus. A great amp designed for 6L6 with midrange lucidity to die for, the bass was OK but definitely a bit of an afterthought. Fabulous for a lot of unamplified acoustic, classical for example. But rock, no, not ideal imo.

I also tried 6L6 in my Primaluna amps.
Same story, basically.

I guess I'll get told that it's all about the circuit not the valve type. Maybe so, but I suspect that circuits are also designed around the valves they are intended to work with.

 

[JANDL100]

BTW, I really liked TAD 6L6. Tauter and more dynamically nuanced than several others I tried.