Conference napalm::guitar

    Also, Marshall is producing their own EL34's these days.
    
    I could live with just Mesa, GT, and RCA for choices...
    
    wjb

	This will certainly change the price on tubes and it will mean
an increase. Mesa use to get alot of there tubes from Sylvania and GE.
	Most of the other tube manufacturers are foreign,like Phillip's
of Canada and there are some manufacturers in Europe(Telefunken?) and the 
Soviet Bloc.
	It may also have an effect on Tube amp prices... 
    
							Rick

Sylvania is the largest supplier of tubes to Mesa. The way it works (according
to Randall Smith) is: Tubes that meet Mesa's standards (the toughest) are 
bought up by Mesa. The next in line is Peavey, and those rejected by Peavey go
to GT. So, even though they're matched, they accept the lowest standards for
tubes.

I think I had better call Boogie and order about a 5 year supply.......

The problem of course is that Randal Smith worked with the old codgers at
the sylvania tube division for a long time to come up with the tubes he will
accept. They did some slight design modifications from the earlier tubes to
come up with the current STR-415 standard and its relatives. Now he'll either
have to make the tubes himself (way too much investment here) or find someone
else to make them (equally as tough since there's such a small market for 
tubes these days that no company in its right mind will invest in changes.)

It is my guess that Randall (If the sylvania tube operation really *does* close)
will come up with some electronic inovation to make it NOT MATTER what the 
quality of tubes (within reason) you put in a Boogie. But this will probably 
only buy him a couple of years. How long will it be before RCA gives up on this 
dying industry ???

-BAP

    	I am getting ready to change out the tubes in my amp and I noticed
    that some distributers offer *matched* tubes. Some examples would
    be Mesa Boogie, Carvin(GTs), and Groove Tubes. What is the meaning of
    *matched tubes*? Identical electrical parameters? What would be
    the advantage of *matched* versus unmatched? The tubes I will be
    changing will be 6L6 GC and 12AX7s. Any clues??
    
    Slightly confused,
    Don
                                      

    
    Re: tube matching
    
    A common amplifier configuration used in many guitar amps is the
    "push-pull" configuration.
    
    What this means is that you have *pairs* of output tubes (your 6L6s).
    One tube "pushes" the other "pulls"; i.e. one tube drives the speaker
    cone forward, the other pulls it back.
    
    For minimum distortion of the waveform, you would like the amount
    of push and pull available to be the same, thus you want the tubes
    matched.
    
    It can be shown on the service bench that matched tubes provide
    less distortion and more usable volume than mismatched tubes.  

    BTW this is a simplified explanation, which I assume is what you
    were asking for....
    

    More on matched tubes:

    In case it wasn't clear from the previous message, tube matching is
    only a factor in the output power tubes (in your case 6L6s, other
    common types are 6V6 and EL-34).  12AX7s are used in pre-amp stages
    and you don't need to match them.  In fact, each 12AX7 tube contains
    two separate tube circuits which are in a sense already "matched"
    (by virtue of sharing a number of physical characteristics).

    The advantages of tube matching in an amplifier output circuit are
    more power, less distortion, and longer tube life.  However, for
    applications such as guitar amplifiers, I think the need for tube
    matching has been overstated by companies who make money convincing
    people they need matched tubes.  I know two very good amp mechanics
    who have told me that any pair of tubes from the same manufacturer
    will do; the tubes are close enough that differences in power,
    distortion, and tube life are negligible for these designs.
    Output tube matching is critical for military electronics
    and hi-fi, but not rock and roll.

    /rick
    

    	Thanks Rost and Rick! That clears things up nicely. I will
    go with the matched power tubes.
    
    Thanks again,
    Don

    If you are rally serious about "Matched" tubes balance your amp
    instead. You may hve to add a couple of pots into yourpower output
    stage but you can use standard tubes and save the money. The things
    to be gained are as previously stated and adjustment is simple if
    you have the test equipment. It only takes a few minutes to do.
    
    Jim
    

    Just who *does* make tubes for GT & Mesa?
    
    

    
    
    	 The transistor started to develop  just after the WWII using
    Germanium, late 50's the the Silicon transistor was being mass produced
    appearing almost exclusivly in consumer goods by the early 60's.
    
    	Most of the British & American valve making plant was sold to the
    developing Baltic states (Eastern Block) save some specialist UHF stuff 
    which is still used today for the military.  As the demand dropped off
    in the East for valve (tube to you US folks) technology the majority of
    the plant went to China who now produce 90% of all valves in the world
    & according to my mate Phil at Marshall they are the best ever, they've
    made them more robust internally & squeeze more out of them so I guess
    they ain't all bad eh?
    
    Cheers
    		Pete.

    
    > China who now produce 90% of all valves in the world
    
    Good, after the next political upheaval, all the tube amps in the world
    will be idled...
    
    8^)  8^)  8^)
    
    							Brian

    Anyone know anything about this new TRANSISTOR preamp tube...supposedly
    it just replaces V1 in an amp or preamp, never goes bad, interfaces
    with other *real* preamp tubes, and is supposed to SOUND just like the
    best Groove or MESA preamp tube...
    
    Anyone?

    
    Mesa used to offer a "FET-tron" transistor tube substitute that
    replaced the first 12AX7 in your amp to provide a quieter front end. 
    The first Boogie I ever saw/heard, back in 1980, came with one of
    these, plus a 12AX7 to pop in if you preferred all tube raunch. 
    Apparently, they stopped making them, perhaps someone else has started?
    
    BTW, Groove Tubes has been making solid-state replacements for tube
    *rectifiers* for years.  I have a 5AU4 replacement in my Bassman.
    
    						Brian

    
    re.12
    	Hmmmmm I'm dubious, I believe in using the right tool for the job,
    so use valves in a valve amp.  Maybe I'm paranoid or something but I've
    never rated any Hibrid configs I've gotten my mits on.
    
    Cheers
    		Pete.

    Brian, what's the purpose of the 5AU4, and what's the differnce
    betwixt that and a 5AR4??
    
    Edd

    
    I *think* 5AU4 was the number, anyway it's a tube diode, uh maybe a
    couple of diodes?  Anyway, it's used as a rectifier...the schematic I
    have for my amp shows six diodes (3 + 3) and not a tube...you figger
    it.  It's a large bottle, similar in size to a 6L6.  
    
    The GT replacement is a small thing, looks like a mushroom  8^)  8^)
    and plugs right into the tube socket.  Some folks argue tube rectifiers
    are better as the supply voltage comes up more slowly.  Anyway,
    *everybody* uses solid-state rectifiers these days in tube amps. 
    
    						Brian

    Nope, not in my office, but, if you're interested I do have a print-
    set for the Ampeg at home.
    
    Edd

    Groove Tubes (GT Electronics)
    Box 4753
    Sylmar, CA  91342
    
    (818)362-1551
    
    GT will be glad to provide you with a copy of their book: "The Tube
    Amp Book" by R. Aspen Pittman. It lists for $15.00 and explains
    just how tubes work and why matched tubes perform better. There
    is a section on amplifier modifications for Marshalls, Ampgegs,
    Fenders. There are some articles like: Survival tips for Tube amps,
    Troubleshooting your Tube Amp. There's a tube cross-reference guide
    and then there's a section that gives a paragraph on each type of
    tube they supply. A large part of the book contains schematics for
    many tube amps (probably the more popular, but there are exceptions).
    For the tube die-hards out there, you'll enjoy the reprint from
    Guitar Player (Oct 88) of "My All Time Favorite Amps". 
    Additionally, there's a current Tube Amp Manufacturer directory.
    
    I've got an extra copy (one) available if anyone wants it (new
    condition) I'll UPS it to you for $14.00. First come - you get it!
    
    Play on,
    
    Paul

    BTW folks,there are 2 printings of this book which have been published
    so far and a third was due in Feb/Mar and I heard it is
    late....It is suppose to be updated to have more than previous issues.
    
    							Rick