Conference napalm::guitar

    Well, I know the Groove Tube EL34s are a little warmer sounding
    than the 6L6s...a little more compression happening.  Never 
    heard of these 5881 beasts...also interested in hearing more info
    on them.
    

    I am not sure exactly what kind of sound you are looking for,
    but it would help if you mentioned what model amp you have.
    
    I just recieved the Book "The Tube Amp Book" by Asten Pittman.
    He is the founder of the Groove tube company. This book has
    a brief history of tube amps, a summary of the major man-
    ufacturers, general maintainance procedures, and some mods
    that are relatively easy to make. For instance, they tell how
    a Fender amp can be converted from 6l6 tubes, to EL34's. All
    it requires is changing a few resistor values. I believe they
    mention the 5881 tubes. If I am not mistaken, a lot of Ampegs
    used 5881's. Ampegs always had the reputaion of being very
    loud amps, and you could not get a sweet sound out of them
    unless you were playing at colliseum volume levels. I used
    to own a B22X which was a good example of an amp that was just
    too damn loud.
    
    You may already know this, but Groove Tubes does not actually
    manufacture tubes. They purchase tubes, most likely from the
    same foriegn manufacturers as everyone else. Groove tubes tests
    tubes on a tester that applies full bias current (unlike the
    Radio shack testers which can only determine if the tube is
    live or dead) and sort them into the various ratings. Since
    all tubes are manufactured in the same process, they are gener-
    ally close in value to begin with. 
    
    If you are using something like a Twin Reverb (4 6l6, 130 watts
    rms into 8 ohms) you probably find that you have to crank it
    up to about 8 before it will distort. Usually by that time,
    the cops are at your door telling you to turn it down. Installing
    a set of groove tubes with a 1 rating may make the amp distort
    at 6 or 7, instead of 8, but even at 6 or 7, a Twin reverb is
    too loud for any practical purposes. 
    
    By the way, to buy a complete set of groove tubes for a twin
    reverb (through Wurlitzers) cost me about $175. Add a few more
    bucks to get your amp bias checked, and you are talking ~$200.
    If you are looking for something to provide a good distortion
    sounds, you might want to check out iether a Chanler tube driver,
    or Real tube ubit. Both are available in stomp-box or rack nount,
    for under $200, and may be a better investment than a set of tubes
    that might, or might not give the sound you want.
    
    Mark
    
    
    
    

    I am told that many of the 1950's vintage amps used the 5881's.
    I plan on picking up a pair today and putting them in my Fender 4x10 
    Bassman.  
    
    Is the Groove Tube EL34 equivalent to a 6L6?
        
    Stan
    

    
    Stanley,
    
    The EL34 is a European tube commonly used in Marshall amps.  For a
    number of years, all Marshalls sold in the US had 6L6s for maintenance
    reasons (they were easier to get) and a market for "British" Marshalls
    started to grow.  Because of this, many players now want EL34s in
    their amps.  They will fit 6L6 sockets but need rebiasing to work
    properly.  
    

    Marshalls sold in the US for many years typically had 6550s, not 6L6s. 
    I think they've gone back to the EL34s now, as they have a warmer
    smoother sound.
    
    Greg

    For what it's worth, MCM electronics sells 6L6s for under $10. each in
    single quantities, down to 5 and change in larger lots.  They're from
    Sylvania, GE, etc., and, in all liklihood, are the same tubes you'll
    get from GT for 2 or 3 times the price. (They also carry 12Ax7s, EL34s,
    6551 [those are $28. if I remember correctly], etc.).

    Oh yes - see note 1061.3 for MCMs address, as well as note 1240 for a
    general discussion of generic vs super-duper-improved-green-granule
    tubes.

    Marshall used 6550s for output tubes from (at least) 1982 (the year
    they got their distribution rights back from the Rose-Morris co.) til
    1987.  They switched back due to the large demand from guitarists for
    the original sound obtained frmo the EL34s.  Not sure exactly when the
    6L6s were part of Marshalls manufacturing, although some of the earlier
    models designed for `cleaner' tones used the 6L6s. 

	The latest Stewart McDonalds Catalog has matched sets of 4
	Groove Tube 6L6GC's for $105.00 and 4 EL34's for $70.00,
	just in case you are looking for price comparisons.

							Jens

    Here's a fairly descriptive response I received from a friend re: 6L6's
    vs. 5881...
    
...Also noticed your question in notes about 5881 power tubes. I own a couple
    of tweeds myself and they have 5881s in them.
The tubes look pretty old, but they sound ok and I haven't had to replace them
yet. 

I checked some old tube manuals and amp books last night; from what I can tell,
the original 6L6 tubes had metal cases.  Someone introduced a replacement tube
for these with a glass case, which was the 5881.  Then later on, they started
making 6L6s with glass cases, which were called 6L6-GC (for glass case).  The
5881s are plug compatible with the 6L6-GCs, but have a smaller glass case. They
also have a slightly smaller linear operating range, hence they saturate sooner
(i.e. the output wave gets non-linear at less amplitude and with less input
signal).  This causes the amp to sustain and break-up a little easier. 
Btw, you can use 5881s or 6L6s in Fender amps, with no modification either
way.

I also noticed that the bases on the old 5881s are significantly smaller than
the 6L6-GC.  On my amps, there are stabilizing clips on the output tube
sockets which would have to be removed if I wanted to put a 6L6-GC in there
instead.  In fact (as Rick may have told you) I bought some GE 5881s from Hal
at Guitronics that had the larger 6L6 style bases; I'm just keeping them as
backups right now.  However, I have seen a lot if amps with old 5881s in them,
and they always had the smaller bases. 

Groove Tubes sells what they call an "old style" 6L6-GC, which sounds like its
similar to a 5881; i.e. they have a smaller glass case and they saturate
sooner.  Another thing about Groove Tube rating numbers; they go from 1 to 10
(soft to hard) so supposedly a "1" 6L6 would be closer to the desirable
characteristics of the 5881.  However, I've been told that GT ratings at the
extreme ends of the spectrum are difficult or impossible to find, i.e. tubes in
the 4-7 range are fairly common, but the high and low numbers aren't.  Don't
know how true this is (it makes sense) but you may have trouble getting really
soft 6L6s from them. 

I don't know how much of the 4x10 Bassman lore you're into, but they are one
of the most copied amp designs ever.  The MKI Mesa Boogies were based on it,
and the original Marshalls (JTM-45) were exact duplicates of the Bassman
circuit.  American tubes were tough to get in Europe, so in the late 60's
Marshall switched to the similar European EL-34 tube, which altered the sound
a bit to what is now the classic Marshall sound.  However, the pre-amp section
of the straight, 4 input Marshall (not the channel switchers) is still to this
day virtually identical to the 4x10 Bassman pre-amp (I've checked the schematics).
Marshalls are just Bassmen in drag :-)

Good luck.

    re: buying single tubes; the reason groove tubes(and others sell
    sets is because the grids inside are not all aligned the same way
    so some tubes will be performing differently resulting in the amp
    sounding really buzzy ....you may be able to get around this by
    re-biasing the tubes(all of them) but on the whole buying a TESTED
    MATCHED SET will give you less headaches and hold up longer
    --Bill

    No doubt close tolerance matched parts are a nice idea, but it seems to
    me that this is much overrated when applied to something like a guitar
    amp, in which the tubes may end up being the ONLY components with that
    kind of tolerence.  As far as biasing goes, it's my understanding that
    the bias should be set every time you change power tubes, even with the
    exhaulted groove tubes.  Gee, sometimes I wonder how musicians managed
    to play at all before GT came along & there was nothing available but
    GE, Sylvania, etc. 8^)

    I agree with -1.  I bought a matched set of GT 6L6's for my Twin plus
    all of the GT preamp tubes and, for the money I spent I absolutely
    do not believe it's worth it.  On the other hand if I had plenty
    of $$ I'd change my tubes after each performance like Larry Carlton
    does. ;^)
    
    joe.

    re: .-1
    
    Larry Carlton changes tubes after each performance?  Are you *serious*? 
    Seems a bit excessive...
    
    Greg

    I think so.  Seems as though I read this someplace...
    
    	Any L.C. fans know fer sure?
    
    	BTW, I do believe he uses Groove Tubes also.
    
    	joe.

    Must be nice to have money (and tubes) to burn...

    Let me shed some light:
    
    The 5881 is a differant tube then the 6l6GC, in both sound
    and voltage specs.  They also put out less power.  BUT, they are the
    sound of the old Fenders.
    
    The Marshall JTM45's used the UK version of the 6L6, the KT66.
    this is the best of it's type, and much larger and stronger
    then the 5881 or 6L6.  It is out of production, since GEC sold
    their tube building gear to China.  IF you find any, grab them!
    
    As a Groove tube resale repair shop, let me tell you, nothing
    sounds better then matched tubes.  Before GT, radio shops
    half-assed matched them on tube testers, or not at all, but also
    specs were kept closer from batch to batch.
    
    Replacing tubes every night is stupid, and I offer $$$$$ to anyone
    who can show a sound advantage, unless the amp is broken and
    burning tubes for lunch.  nuff said!
    
    BUY the new 12AX7wa's from China!!!!!!! they are the quietest 12AX7
    ever made!!!  Never use 7025's, they sound bad.
    
    EL34's and 6L6's cannot be interchanged!!!!!  don't even try!
    
    Watch out for the new KT-90!!! Buy them !! replace 6550's, 6CA7'a,
    EL-34's with them!!!  Samples are unbelivable!!!!! Coming soon!!!
    
    If anyone needs tube spec sheets and reprints of the Gold Lion/GEC
    manual, e-mail me here.  IF you need replacement or new transformers,
    try Triode Electronics in Chicago.  E-mail me for address & phone ##
    as I don't have it with me.
    
    Jay Tashjian
    

    
    >EL34's and 6L6's cannot be interchanged!!!!!  don't even try!
    
    Unless you have a Kittyhawk with the switch built in.  ;)
    
    What are KT-90's ?  How would one wire up a Marshall that uses 
    EL34's to run KT-90's ?
    
    jc

    
    Besides the Kitty Hawks, I know of at least two other amps that allow 
    you to use either EL34's or 6L6's. Peavey's latest tube power amp line 
    (ie: the 60/60), and Mesa Boogies Stratagy 400. I believe some of
    Peavey's VTM series heads/combos also allow you to interchange EL34's
    or 6L6's.
    
    The Strategy 400 derives it's 200wpc from 6 power tubes in each channel. 
    The optimum configuration for guitar is 4 6L6's and 2 EL34's in each 
    channel. If you replace the two EL34's with 6L6's the amp operates like
    a high fidelity sound reinforcment amp.
    
    The Mesa Boogie 295 Stereo Simulclass also mixes EL34's and 6L6's but
    they are not interchangeable. The EL34's provide 35 watts of power,
    and the 6L6's triple the power to 95wpc. This is the whole premise 
    behind the "Simulclass" design principle.
    
    Mark
    

    
    Taken and reprinted without permission form Mesa Boogie catalog.
    
    "SIMUL-CLASS POWER
    This exclusive, patented MESA/Boogie innovation...
    ...It accepts different types of power tubes which you can change 
    easily yourself: use four 6L6's for the biggest, fattest, warmest
    sound.  Or substitute 2 of our special EL-34's for wall-busting, ball
    crunching, grining British-type power.  No other amplifier lets you do
    this, and no internal adjustments are ever required."
    
    My MK III sits with 2 EL-34's and 2 6L6's inside...
    
    J.