Conference napalm::guitar

    It's time to replace the power tubes in my Carvin amp.
    
    ******How do you know?
    
    It was originally outfitted with 2 Groove Tubes 6L6s. 
    Are name brand tubes (Groove Tubes, Mesa Boogie, etc.)
    worth it? Specifically:
    
    -Do they sound any different from vanilla Sylvania tubes?
    
****** Perhaps the "quality control" is tighter on these tubes
at the manufacturer or the vendor/middle man(Mesa and GT). However
tube manufacturers will ship just about anything that meets there
requirements,the difference is whether the middle man(mesa&GT)
will accept anything. This is kinda what they are doing by creating
or supplying a better "specified product". 
	So I believe and my experiance is they may sound better.

    -Do they last longer?
    
****** Well,this is hard question to answer with what data I have,It's
the MTBF of the tube. However if you start out with something of higher
quality and meet's more stringent standards and specifications I would 
expect it to last longer or at least to provide a higher standard of
performance. Some of this is directly related to your usage... I've used
GT's for a year now,but I'm probably give Mesa a try next. I had no real
horror shows,Mesa's are easier for me to find.


	Bottom line buy whatever you can afford,because there's always
something better and more expensive.

						Good Luck,

							Rick

    
    
                      They sound a little better,  but more expensive.
    
                      Daddy's is selling Peavey matched 6l6s for $25.
    
                      That'll probably save you $10-$25 over the other
                      "brand names".
    
                      I bought a set of the PVs and my Marshal sounds
                      great.
    
    
                      As far as Sylvania or GE or National,  they will
                      sound as good if you can find a matched set.
    
                      I couldn't find any "generic" tubes in a set so
                      I went with the PVs.
    
    
                                                    Chris
    
        ps  Foster TV in Pelham N.H. or Macartins Elect. Dist. in Lowell
            have most kinds of amp tubes for FAR LESS than any music
            store.
    
    
            12ax7s for $5.70 each  or 6l6s for about $9!!!
    
    
                                                             

    I used to have an old Music Man outfitted with Sylvania tubes and
    people always thought I had the thing modified as it had such B*lls,
    gain and sustain, so no, I don't think the tube brand matters too much. 

    Thanks for all the replies. I went to Daddy's at lunch.
    They are all out of Mesa and Groove Tubes in 6L6. They
    also mentioned that Mesa won't be selling their tubes
    to dealers anymore. They quoted a price of $30 per matched
    pair of Groove Tubes.
    
    re .1
    
    I had the amp in for repair. It was cutting out intermittently
    The repair person said that an element in one of the tubes was
    loose.

    
    Excuse me...but how can you really tell the difference in the sound
    between the Top_of_the_line tubes and the Brand X types?  And has
    anybody ever donew a side-by-side comparsion of matched vs unmatched 
    sets of XYZ brand vs Top-on_the_Line tubes?
    
    With all the variables involved with producing a sound, it would
    seem that type of tube installed in an amp would contribute an
    almost undetectable amount to final sound quality coming from the
    amp...
    
    Marketing hype?  Reality?  "My tubes are better/more $$$/matched
    than yours"??
    
    What are the facts?
    
    D.C.
    
    

    
    Re: .5
    
    All that happens with the "premium" tubes is that they are screened
    for performance (which is why there are more expensive) but you
    *might* get a tube just as good or better out of a TV shop, but
    it's a crap shoot.
    
    I've heard lots of stories over who makes what tubes, which brands
    are screened most tightly, etc.  As far as I know, up to a few years
    ago only RCA, Sylvania and Raytheon were still in the business in
    the US, and recently I read that one of them (RCA, I think) was
    going to stop production.  This means all tubes regardless of brand
    name are made by one or maybe two companies, unless they are imported
    (the eastern bloc is now a large supplier of tubes).
    
    Matched tubes are no hype.  In a push-pull amplifier, matched output
    tubed produce more clean power and lower tube wear.  Running one
    worn tube and one fresh tube in a power amp will actually cause
    the fresh one to wear faster.   While it might be argued that worn,
    unmatched tubes provide *more* distortion it's usually not usable.
    Tube fans probably know well the sound of a set of tubed ratting
    out.
    
    In the preamp, the only thing you need to look for are microphonics
    and how quiet the tube is.  Mesa screens some 7025s for super-low
    hiss and charges big bucks for them, this may be worthwhile for
    studio use.  Other than that, if the tube is not microphonic, for
    preamp use, it's probably OK.  
    
    The only flat out disclaimer I have ever seen on tube amps is that
    Mesa claims 300 watts out of the Bass 400 amp head *only* if you
    use the Mesa 6L6s in it (300 watts out of only 6 tubes is pretty
    agressive).   

    While I don't doubt the advantage of matching output tubes, I do
    question whether or not you need to pay anybody to match them for you.
    I have been told by a prominent amp technician in the Boston area,
    one who is well known and regarded for his expertise with tube
    amps, that a pair of new power tubes from the same vendor will be
    close enough to cause no problem in musical instrument amplifiers.
    He backs up this claim with practice; i.e. he just grabs any pair
    of Sylvania 6L6's from the box when retubing (unless someone
    specifically asks for name-brand matched tubes, which he'll gladly
    order and charge twice as much for).  I can believe that hand-selected
    carefully matched tubes might make a discernable difference to an
    audiofile in a hifi system, but not for guitar amps.  It's enough
    to make sure you replace all the output tubes at the same time.
    Specially matched tubes for guitar amps is IMO a lot of hype and
    a waste of money.

    /rick    

    
    
                   It won't make a big difference in the sound....
    
                          
                   but,  It definitely makes a difference in longetivity!
    
                                                         Chris

    Hmm longevity eh? My original tubes are still in my music man 7
    years later with no degradation in sound or output power. Standard
    run of the mill sylvania tubes....I doubt if MM matched them.
    
    dbii
    
    

    just to clarify, my impression is that specially matched
    power tubes will not significantly increase the sound OR
    the longevity over a random pair; again, just what I've heard
    from what I consider a reliable source.
    
    /rick

    ps the "unmatched" Mullard EL-34s in my Marshall are 20 years
    old (no exaggeration) and they still sound pretty good, just
    ask Buck.

    .9, .10
    
    The repair guy that I talked to felt that it's all in the
    way the amp is designed. Small combo amps like mine tend to eat
    tubes. The power tubes hang about 1" away from the speaker.
    They are subject to alot of vibration.
    
    In a Marshall top or a Musicman, the tubes are probably 
    better protected, hence the long life span. That was his feeling
    anyway.
    
    -Tom

      Since all my amps are tube (2 Kitty Hawks, 1 Marshall) are all
    tube I've found these comments interesting. I've heard somewhere,
    maybe another topic, that the Mesa Boogie tube have the highest
    standards followed by Peavey, then Groove Tubes. There is also a
    new company called AudioGlassic that I saw an ad for but never heard
    any info on. I know that a lot of tubes are not only imported from
    Europe but the USSR and Red China as well. Maybe they still use
    them in their computers! I've heard good stuff about the quality
    of the Chinese tubes, maybe worth checking out. 
      An interesting thing about the Kitty Hawk amps is that they are
    the only ones, as far as I know, that provide a bias switch for 
    changing between 6L6 and EL34 power tubes. I prefer the sound of EL34's
    but according to the distributor the 6L6's are more reliable.
       

    
    
                    I owned a tube amp for about ten years and never
              had to replace the tubes.  Of course,  I only had it 
              cranked up about ten times for an hour or so each.
    
                    When I started gigging regularly with it,  it took
              only four shows to blow.
    
                    The reason for matching tubes is to balance the
              halves of the push-pull amp.  If it is not balanced, one
              half of the amp will have to work harder and consequently
              burn out. 
    
                    How can you say that the tubes in your amp are NOT
              matched?  Musicman and Marshall have always built a quality
              product.  I do believe they would have incorporated the
              basics of reliability into their design/assy process.
    
                    Also,  musical instrument production (esp. guitars
              and amps)  has increased dramaticly in the eighties.
                    With higher production volumes there may have been
              a few compromises to cut costs.   So,  I'm not surprized
              there are some old-timers still kickin A.
    
    
              
                                             Chris
                       

    
    
    	Any ham radio enthusiasts out there?  I'm not a ham but I go
    to a few hamfests and look over the old radio gear (pretending that
    I know what it does)... "why the hell is he telling us this?", you
    may be asking.  Well, ummmm... I just think it's interesting that
    my two favorite hobbies have such an interesting LINK.   Listen,
    I go to HAMFESTS and buy power tubes and audio tubes (you know the
    big ones with the sixes and the little ones with the twelves) for,
    oh... anywhere from .50 to 2.00 a piece... then bring em' back to
    my favorite music store (where they pay 17.50 to 30.00... new, I
    admit) for the same tubes, and amaze all my tube amp playing friends.
     I wonder if there is an opportunity to make large amounts of cash
    here???    Funny how so very few of my ham friends hang out with
    my music friends...
    
    
    Steve

    My musicman has the tubes about 4" from the speaker. Vibration is
    present at all times (trust me with me playing they vibrate:-))
    
    As far as being matched, the owners manual doesn't mention it, or
    any need to replace them with matched tubes.
    
    I do understand push/pull amps and the IDEA of matched tubes sounds
    good on paper, I find it hard to believe that in practice it makes
    any real difference at all. If it does, I'd suspect a poor design
    in the first place.
    
    dbii

    As for longevity of tube life... My brother bought a Fender Reverb
    Unit in 1957 (it was the year after my family moved to the U.S.A.),
    and guess what, the tubes are the originals (it's an old white
    reverb unit & I've taken it all over in the last 20 years). Currently
    I use it in my home studio set up.

    As for other products, My 6L6GC's don't get changed (never been
    matched) in my Fender Twin Reverb unless one gets sick. I carry 2 spare
    6L6GC's with me (they are quite old) & I'm running 2 Phillips and 2
    Radio Shack 6L6GC's on mine at the moment (no tube changes in the last
    4 years).

    I recall that some TUBE amp designers set thier plate voltages quite
    high (Marshall comes to mind), and this will cause pre-mature tube
    failure. Fender never did this (that I'm aware of) & I'd suspect 5 to
    10 years is expected tube life for them.

			Jens_who_took_classes_on_tube_amp_design_back_in_
			college_in_1972_&_prefers_tubes_to_transistors_in_
			guitar_amps.

    In case anyone missed this, I'll try ONE MORE TIME.
    Yes, "matched" output tubes are good for your amp.
    No, you don't have to pay mega-groovy to match them for you.
    New tubes from the same manufacturer are sufficiently matched
    for musical instrument applications.

    IMHO, of course :-}
    

    Like dbII in .15...my musicman combo (1x12) had the power tubes about 1
    1/2" frmo the speaker.  I used to crank that thing all the way up, and
    watch the tubes change color from gold to amber to blue to dark purple
    as they overheated and saturated to the max.  This amp has the
    ballziest sound!!!  I never need to replace the power tubes in that
    thing the 4 years I owned it, and I played it on 10 every day.  I was
    sorry the day I traded it for a marshall. 

    Got a marshall you'd trade for one?
    
    dbii

    I bought a new Fender "The Twin" a little over a year ago. Within
    the first couple of weeks, I started hearing a buzzing sound which
    I eventually isolated to microphonic power tubes. All 4 of the
    power tubes seemed to be microphonic. I arrived at this conclusion
    by swapping them with some 6l6's that I had kicking around the house
    for years (probably 7-8 years old at least). None of the old tubes
    were microphonic. I called Fender one day, and a girl in the service
    department told me they were covered under the warantee. She gave
    me the option of mailing the tubes directly to Fender or bringing
    them back to the dealer. I opted to return the tubes to Wurly.
    Naturally, the salemen at Wurly gave me a hard time about accepting
    them. I told them to call Fender and ask for this girl by name,
    and she would arrange to replace them. It took me months of constant
    reminders to get Wurly to replace these tubes. Finally after several
    months of waiting they gave me 4 tubes which (for all I know) were
    probably purchased at Radio Shack just to humor me (there is no
    Fender logo on any of them, they look about as generic as you can
    get). The saleman claimed that these are the tubes Fender is using
    in all of it's new amps. Should I believe them ?? Like I told the
    saleman, as long as they sound good, I'm happy.
    
    Anyways, the old power tubes that have been kicking around my house for
    years (and were used to gig for about 3 years before being retired)
    are still in my new Twin, and sound great. I probably won't replace
    them until they give me grief. The nice thing about the new Twin
    is it has test points on the back which allow the owner to set the
    bias and hum balance with a simple DVM or multimeter.
    
    I also have a 1977 silver face Twin Reverb which is completely tubed 
    with Groove tubes. Between the 4 6L6's, and 6 preamp tubes, I spent
    $175 tubing this amp, not to mention an additional charge for setting
    the bias. In my humble opinion.....never again.  There are a lot
    of great used amps at there that I could buy for $175. To spend
    that much on a set of tubes again, seems like a waste to me.
    I am not saying there is *no* value added associated with buying
    name-brand matched tubes, but for my money (and my ears), I don't feel
    it makes a significant enough differance to justify the expense.
    I suppose if someone plays professionally and can write off retubing
    an amp as a business expense, it makes sense to buy the best, but
    for someone into music as a hobby, I can't see it unless you have
    money to burn. Another thing is that there is little or no differance
    between name brand preamp tubes, and generic preamp tubes, since
    these are never sold in matched sets anyways. I don't believe that
    GT or Mesa do any special testing on preamp tubes, so why pay $12/each
    for them, when you can get a generic preamp tube for 1/2 that.
    
    Again, this is just My humble opinion.
    
    Mark
    

    
    
    
                     O.K.   O.K.   !!!
    
    
                     "matched" tubes won't give your amp wings.....
    
                            or make you play like Jimi Hendrix.......
    
                      but from a design standpoint they are theoretically
                                                                  better.
    
                      Enough about matching.  I agree that tubes of
                      the same value and manufacturer will be
                      "good enough".   
    
                      As far as where to buy,  I would never spend
                      $100-$200 to retube.  You can probably replace
                      all the tubes in a Fender for less than $70.
    
                      Electronics warehouses and the SMALL TV shops
                      are the most economical vendors by far.
    
                                         
                                                      Chris
    
              
     
              

    re: .20
    
    > I don't believe that GT or Mesa do any special testing on preamp tubes,
    > so why pay $12/each for them, when you can get a generic preamp tube
    > for 1/2 that.
      
    Just a wag, but Mesa preamp tubes (12AX7s) cost only $7 each.  The
    cheapest I could find them (at electronics shops) here in Co. Springs
    was about $6.50 anyway, so I opted for the Mesa tubes since 1) I
    could get them more quickly (the one and only electronics shop that
    had any new tubes was out of them), and 2) I was told that Mesa
    screens their tubes and rejects the lower quality ones.
        
    I agree that $175 is more than I'd want to pay to retube an amp.
    
    Greg                                                            

    
    	Re .14 - yeah, I do the same - let "somebody else" walk away
    with 6 or 8 6550s for $5, cause I "didnt want to carry the powersupply
    they came out of"...Neither did he; *he* talked the guy into selling
    him just the tubes for $5 - (***STUPID***)
    
    	Anyway, most power output tubes burn out because of the
    design of the amplifier, rather than  because of them being overdriven 
    or too close to the speaker.
    
    	There's a reason for that "Standby" switch ya know - you're
    supposed to initially warm up your amp for a minute *first* with
    the switch on standby. This insures that the glowing elements of
    the tubes are "up" before the voltage gets applied. When B+ voltage
    gets to the tube *before* it's heater is fully red hot, the tube suffers,
    and does not last as long.
    
    	Some of the better amps have "delay relays" for this purpose
    or special rectifier tubes with controlled heating elements (GZ34,
    5R4) vs the more common 5U4 and 5Y3 rectifier tubes. Amps with these
    features will keep their original tubes for a long, long time.
    
    	Some of the cheaper amps, Oh Great Marshall included, have solid
    state rectifiers, which provides B+ voltage immediately on power up. 
    This rips the sh*t out of the output tubes, and consequently, they last
    only for a few years instead of 10s of years.
    
    	BTW, it's been pointed out that Marshall uses a rectifier tube 
    in their latest "re-issue" amp. This does more, apparently to the sound
    of the amp, than one would guess at first try. Whoever can guess
    correctly what's happening gets a cookie -
    
    	So, if you want to save your output tubes, *use* that standby
    switch!
    
    	Joe Jas
         

    This being the 24th reply, it probably won't get read, but I had
    to get my 2c in about tubes. I use Mesa amps and Mesa tubes. 
    
    Mesa boogie *does* test the 12AX7s and offers two types. One is
    a heavy duty (non non non microphonic) tube that I put in my main
    amp. I am running two Boogies in stereo and the band PLAYS LOUD
    so I outfitted the main amp (the one I use the pre-amp section on)
    with the higher quality tubes. 
    
    As far as power tubes, matched tubes will make a difference in the
    life of the other tubes, and a difference in the sound DEPENDING
    UPON THE AMP. In my case, I can hear and definately distinguish
    a difference in clarity, presence, and punch especially at loud
    volumes using matched tubes. 
    
    Boogie power tubes used to *not* be matched, because they were simply
    rejected if they didn't meet certain minimum specs. The rejects
    went to Peavey, who kept some and sent *their* rejects to Groove
    Tubes. (That doesn't mean that all Groove Tubes come down this chain).
    
    Today, since SYLVANIA has stopped producing tubes, Boogie now matches
    the tubes they get from CHINA (yes CHINA). 
    
    Boogie dealers are not currently selling Boogie 6l6 tubes because
    the China connection is slow and Boogie is ensuring that their own
    inventory for production purposes is kept up. They only allow dealers
    to purchase 6l6 tubes for repairs. That is not to say that this
    is a permanent situation. However, now that Boogie is simply matching
    6l6 tubes like everyone else, I might as well go to Foster TV (I
    saw it mentioned in an earlier reply) where I used to work in H.S.
    and see Mr. Foster and maybe get them for even less.
    
    I believe there are 3 main points here:
    
    1. if you can hear a difference (actual or pshycological) buy the
       tubes that make you happy.
    
    2. I believe that the preamp tubes do more to affect the sound
        than the power tubes.
    
    3. If you gig alot, and the band is loud (onstage) the tubes will
        wear out faster.
    
    In my case, I had previously never turned and Mesa Boogie amp past
    1.5 on the Master volume knob. Now I run two Boogies (a .50 and
    a simul-class colleseium) and the .50 is on 4 or 5 and the colleseium
    is on 2 or 3. It's LOUD!! But I simply can't hear it unless I run
    it that open, so the tubes COOOOOK. (Especially in the .50 with
    no fan.) My set of spare 12AX7s sit Idle in the .50 (since I am
    only using the power section of this amp.
    
    Tubes, Tubes, Tubes, after 24 replies, can anything else be said???
    
    -BAP

    RE: .20
    I thought that I had a isolated case of power tube problems when I 
    bought my FENDER "The Twin" 5 months ago.  It only took 2 trips to 
    the local warranty repair shop, four calls to Fender Customer Service
    to convince them I wanted four new 6L6's.  Fender was even going to
    ship the amp to Cal. to have it repaired if I did so choose.  So I
    don't think they have put two and two together to figure that they
    have a Q/C problem with their tubes in their manufacturing process.
    
    The first time in the shop, Fender sent 1 6L6 with the Fender logo. I
    proved the problem to the local tech's by pulling two of the 4 power
    tubes and running the amp with one "good" tube and one of the tubes
    producing a microphonic buzz.  I am still waiting for the 4 new
    domestic 6L6's the warranty shop requested from Fender over a week ago.
    
    I did find out that the 4 original tubes were Chinese.  The new tube
    Fender sent was a GE with the Fender logo.  The Chinese tubes had
    significant flaws when compared with the Fender 6L6.  The base of the
    tube did not mate well with the amp and the glass enclosure had "gunk"
    that looked like rust where the glass enclosure mates with the base.
    Also if you tap the tubes they made a tinny sound.  The tubes did not
    have any markings other than white lettering designating them as 6L6.
    
    The amp works great when the tubes are good.  I was told during
    this process that there are no longer US manufactured tubes. China and
    the USSR will be our suppliers until they upgrade their military
    equipment.  Has anyone noticed an influx of sloopy tubes comming to the
    US?  I hope this is isn't a trend to look forward to over the next
    decade.
                                                  

    As was mentioned in .20, I too have a brand new Fender "The Twin".
    
    I have had noise problems with it on several occasions since I bought
    it. Shortly after I bought it, it began buzzing. If you tapped the
    top of the amp you could tell something inside is was microphonic.
    I swapped the original power tubes with some old ones I had, and the 
    amp ran without any unwanted noise up until about a month ago. My 
    guess is the preamp tubes are now the culprit. I also suspect that 
    there may be other problems with these amps other than tubes. I 
    suspect that my problem may be due to one or more faulty tube sockets.
    My old Silver face twin is completely tubed with Groove tubes, and one
    day I installed all 4 of the Groove tube 6l6's in the New Twin to see 
    if it would perform any better. I use the new Twin as the Master, and 
    the Silver faced as a slave, so I figured I might as well have the 
    Groove tubes in the new Twin. The new Twin acted like it had microphonic 
    tubes with the Groove tubes in it. It buzzed, and if I tapped the 
    tubes, you could here a "plunk" through the speakers. I was forced to 
    screen through several tubes I had at home and settle on 4 that would play
    without noise problems. The Groove tubes ended up back in the Silver
    faced Twin for good.
    
    The amp played fine for a while, then I started hearing a popping
    sound in the clean channel. After a while the popping got so bad,
    I couldn't use the clean channel at all. Eventually (after a few
    more days went by) the popping started occuring on the lead channel
    as well. 
    
    I was in Wulritzers a few weeks ago. Someone was trying out a 
    Roland GP8 through a Twin and all of a sudden a shrieking noise
    could be heard throughout the store. A salesman ran over saying
    it was the &$%^()*# Twin again !! This problem obviously is not 
    limited to a few isolated cases, there is a recurring defects in 
    these babies. If it's strictly inferior tubes causing these problems 
    then you can't blame Fender, and eventually everyone with tube amps 
    will suffer. If it is something other than tubes then it's a 
    differant matter altogether.
            
    At this point I plan to change all the preamp tubes (ouch!, there are 
    5 in this amp) and open the amp up and see if there are any obvious 
    defects like cold solder joints, etc. Like most amps that Wurly sells, 
    this amp served as a demo model for a while. They simply don't have 
    room in the store to stockpile amps, so they set them up as demos until
    they sell, then they get some more from the main store. The tubes
    were probably well used before I ever got it home. Hopefully, once
    I get a completely fresh set of tubes in it, it will be all set
    for a while, because I don't use it very much (only a few hours
    per week). What's ironic, is that I have the New Twin, a silver
    faced Twin, and a Pignose. The Pignose gets used constantly, and
    the Twins collect dust.
    
    Mark
    

    Re: .26
    I have finally fixed my "THE TWIN" for the last time.  The problem was
    with the preamp tubes.  I called the service manager at Fender and told
    him that the local service shop didn't know how to diagnose the problem
    with tube buzz.  Since the power tubes had been replaced with some
    improvement I asked him to send me the other 5 12AX7A's and 2 12AT7's. 
    The service mgr. turned me over to parts for anything I wanted.  I
    asked for all US made tube and all the parts department had were
    Chinese tubes.  When I recieved the tubes the 12AX7A's were Chinese
    with no Fender markings and the 12AT7's were German made with the
    Fender logo.  Fender was not concerned with matching tubes.  They have
    sent me 4 6L6GC by GE, 5 12AT7's which are Chinese and 2 12AT7A's by
    West Germany.  Does anyone else have multi-lingual amps.  Problem
    solved!  No more buzz ma!
    
    Bill

    RE: .25
    
    I just received a shipment of Chinese tubes from Mesa/Boogie. The
    description in .25 is very accurate.  They *look* very sloppily
    built, and they do have a tinny sound when tapped lightly. The 6L6's
    are smaller than the old Sylvania ones, and there are other obvious
    visual differences such as the getter being located near the base
    of the tube, rather than at the top.  They seem to work ok, but
    I wonder about durability considering the sloppy appearance.
    
    I'm afraid it has become time to stockpile replacement tubes for
    the future just in case we reach a point where quality tubes (or
    any tubes at all) are no longer available.  This is unfortunate
    because as more and more people come to this conclusion, tube
    prices will be driven to even more 'unreasonable' levels.
    
    It is interesting to note the reaction from an old-timer military
    radio man when you tell him how much you just paid for a matched
    pair of Groove 6L6GC's.  They think the price is only out of line
    by a factor of ten or so!
    
    /Steve

    
    re: .12
    
    Hi John, why do you like the EL34's better?  Have you tried the 6L6's
    in any of your KH's yet?  I might try 'em out if I can get 'em cheap
    just for fun.
    
    	-pat

    so, I bought a set of EL34's, but, like, where do I plug them in to
    my Peavey Special 130?
    
    -Puzzled Dave

    
    Re -1
    
    	Dave...you got a pair on ya THIS BIG. :^) :^)
    
    	Neal-shaking-his-head-wondering-if-Dave-will-get-flamed
    

    I recently came across an interesting product from the "Audio Amateur"
    audiophile magazine.  There's a company called Pearl from Canada that
    makes these gadgets that are supposed to AT LEAST DOUBLE the life of
    tubes.  It looks like a heat shield, but it slips over the tube and
    dissipates the heat evenly.  Some sample prices (U.S.$):
    
    Octal power tubes $10-$11, Octal small signal $5-$6
    7-9 pin miniatures $5-$6, Specials $15-$25
    
    For more info:
    
    Pearl Coolers
    Perkins Electro-Acoustic Research Lab
    2510 19th St. SW
    Calgary, Alberta  T2T 4X3
    Canada
    (403) 244-4434  [telephone + FAX]
    
    They accept VISA / MC / AmEx

	I put a muffin fan (about 4 inch diameter - Radio Shack sells them)
	near my 6L6GC's on my Twin Reverb & they run quite a bit cooler. I 
	got my fans as surplus for about $5.00. I'm sure this would also be
	effective. Other than tubes working themselves loose over time, I've
	had no problems with this set up.

								Jens

I thought tubes sounded better if they got nice and hot !!

Whats the deal ?  

jc (Who this this, within reason of course...)

    Excessive heat and cycling degrade their life span.

    
    Last night I blew one of my two EL34's (Groove Tube variety).  I have
    only had them a month, and am kinda pissed that one went south.  Are 
    tubes like automotive electronics - you know, nont returnable?  I put
    the 6L6's back in and all was well.  I had an extra EL34 and was able
    to isolate the bad tube.
    
    thought?
    -pat

    Do the tube coolers change the sound of the amp?

RE: Kittys and Tubes...

In my opinion, all these tubes can't be DOA's or Infancy failures...
Something is causing them to fail.  Bias ?  BAd Xformrs ?  Filter Caps ?

What about folks that have Fender and Marshall gear and go with tubes
for 2, 3 or even fours years with out a problem ?  Sheeesh.

How many people have picked up a Kitty and haven't had a problem ?
I know my amp bit the bigun, Steves, Pats...  Even my Patch Bayette 2
lost the MIDI thru port...Great sound, but at what cost ?

jc (Concerned about Kitty)

re .36 Pat....

	I believe GT's are gauranteed for 90 days,if one tube blows there
warranty will cover replacing all 4.... if you bought them at a GT dealer.
	I'd also consider using 6l6's unless you are really into that EL34
sound.....for reliability reasons..... I thought the M1's sounded better
with 6L6's anyway.....
              
							Rick

    re .36
    
    I believe that both Groove Tubes and Mesa Boogie offer a warranty
    for their tubes. Mesa's is 6 months. For the money they charge, 
    GT damn well better. Send 'em back...
    
    -Tom

>  How many people have picked up a Kitty and haven't had a problem ?
    
    I have had no problems, at all, with the M1.  My few minor problems 
    were with LPMG.  The M1 is a killer amp.
    
    Mike

    re: .38
    
    another happy KH camper... 2 M1 heads, no tube problems to date...
    
    Wilbur

yet another happy KH owner - an M3 and Quattro without any problems! 

(knock on wood....)

Alan S.

   Make that (er, um, where were we?)...  One more KH owner without problems.
   I don't use mine for gigging, but it's been through several 4 hour cranked
   practice sessions without a hitch.  And that tone...  Ah.

   -- Sam

My kitty shouldn't really coutn for two reasons, first the problem is mechanical
and not electrical (and not a tube) and second it was used.....


dbii yeah that killer tone!

    I've also had no problems with my Kitty.
    
    Greg

    Man it hurt to read the last few replies. UPS chemically
    damaged my M3 combo. LPMusic wanted to take the electronics
    out of the damaged chassis and put it in a new one. Call me
    skeptical or whatever but I just asked for my money back.
    I figured I was getting into more aggravation than one of
    these beasts was worth. After reading some of the rave 
    reviews I'm begining to wonder again.....
    
    Mark Crombie
     

    Throw my name on the list of folks with NO PROBLEMS, Kitty wise.
    So far, 3 long gigs, about 5 long practices (all 5 hours plus),
    and still toasting !  Gets real hot though .... (?)  Does everybody's
    M3 get too hot to touch the front panel ?
    
    
    				Scary

re:    <<< Note 1240.48 by ASAHI::SCARY "Joke 'em if they can't take a ..." >>>

>    Does everybody's M3 get too hot to touch the front panel ?

   Not mine.  4-5 hours running at 7/8 on master volume and it's NEVER gotten
   that hot.  Slightly warm only.  Never so hot that I couldn't touch any
   part of the amp, except the tubes themselves.  And my tubes glow a full
   orange color - no blue.  Someone told me that means they're running hotter
   than normal, but you can't prove it by me.

   re:  Back a couple

   "Chemically damaged"?  What'd they do?  Sorry to hear of your troubles
   and aggravation.

   -- Sam

    Since my complete tube replacement, I've run the KH M3 head about 25
    hours without a hitch.  Scary, mine most definitely does NOT run so hot
    that I can't touch the front panel.....sounds a little TOO hot to me...
    
    Booldawgster

    - a few
    
      I never really got all the particulars as to what kind of
      chemical damage but the guy at LPMG said some chemical
      soaked thru the carton and got to the amp somehow. They
      wanted to pull the electronics on it and put them in another
      chassis but after all that handling and everything I figure
      I'll at least have tube problems when it finally gets to
      me. One hell of alot of trouble for a an amp that I'd probably
      only use at rehersal.
    
    Mark C

    
    re: .38
    
    Actually, Coop, my original EL34's are still good and I never had a 
    problem.  Also, the generic 6L6's worked well (and still do).  I
    believe that one of the GT's was funky.  I *thought* I heard one 
    flaking out a week ago, but decided to just have another beer.  
    BTW, Musician's Friend saif they'd ship me another duet - no problem.
    Also, seems like Steve and Jerry's Kitty are doing fine now...

How do I best locate a microphonic tube? My Rivera has developed a new
'feature'. Without a guitar I can get some fairly high frequency feedback
just by putting the treble control to wow...

Also what difference 12AX7 vs 12AX7A? I can get the 7A's cheap from my local
shop....

dbii broke down and busted...

    Tap the tubes with your finger, a microphonic tubes will transfer
    the "tap" sound out thru the speaker, with a good tube, you won't
    hear anything.  Or so I'm told...
    
    
    
    
    Don 

	I broke out the old tube manual and from the info I have I can not find
any differance between the two. The are HIGH-MU (high gain) TWIN TRIODES. They 
both have the same pinout and operating voltage. My manual had a section on 
the 12AX7A and for the 12AX7 it refered me to an abreaveated section in the 
back. It is used in class resistance A1 class amplifers. About the only thing 
that looks unusual is  that there is a hum spec on the 12AX7A. In the front of
the book it lists the 12AX7A for use in Hi-Fidelity applications. 
	I would buy the 12AX7A and put it in. It will proably give you a cleaner
sound than the 12AX7 (if thats what you arre after).

Ray

Thanks for the info...the tube(s) is so microphonice that tapping the 
amp chassis from the outside transfers into the speakers...hopefully 
it's a single tube...

re: cleaner/clearer....not to worry this thing has enough gain to overcome
such disadvantages...:-)

dbii

    FWIW Dave,
    
    When I replaced the pre-amp tubes in my KH M3, I got 12AX7A's.  They're
    still crankin!
    
    
    Steve D.

Everything all fixed now. Finding the microphonic tube was tap, tap, tap, TINK
TINK....

I do still have a bit of hum on the super distortion mode of the Kitty though..

dbii

Tube amps humm a little...  Nature of the beast I'm afraid.

jc (who sez: Hush now sweet harlotte !)

    re: .59 You've obviously never played with a Rivera. No hum. I guess
    I'm just spoiled.
    
    dbii

    True... Never played a Rivera...In fact, I'd never heard of one until
    you got yours.  They rock pretty good eh ?
    
    jc (Who needs to get to more music stores and trynew toize.)
    

   
      Add me to the list of no real problems. The only thing I noticed
    was that my preamps (3) run real warm and I don't think there is
    adequate ventilation, so I'm doing  a retrofit top on all my
    TR's and the QT. The tube combo's and M1 head are still running
    fine. 
    
    						-BoOm-

re: Rivera I A/B's the hum between the Rivera and the Quattro. The Quattro has
about 10 times the hum as the Rivera, if you turn it all the way up (120W) then
you can hear hum on the lead channel...

Funny, in the last week I've learned how to set the Rivera up to sound almost
exactly like the quattro in every mode except super distorted, which the Rivera
doesn't have enough gain to do by itself...

I still love the ease of use of the quattro for stage work though..

dbii

	Just an update on the tube market. I had a 6L6GC go microphonic
	on me last week (it was a Phillips, one of those with the 'dual
	getters'), and I replaced all of the 6L6GC with my Chinese 
	6L6GC's. They sounded good in my Twin Reverb (as good as it ever
	has). I also went back to PROSOUND (in Colorado Springs - Phone #
	(719) 597-9962) to get 4 more as spares. They have the SOVTEK tubes
	now (made in the USSR), but at the same sale price as the other
	6L6GC's. They are $6.99 during the month of April. All in total,
	I have 10 known good 6L6GC's as spares. Even tho you might not
	think highly of this brand of tubes, they are idenitical to the 6L6GC's
	that Radio Shack sells (at about $18.00 each), and to be honest with
	you, for the price, I'd rather have a full set of spares that are
	cheap enough to have plenty on hand when you need them. You might
	want to consider getting a spare set, just to have them ($28.00 for
	4 is pretty good deal, and they work as good as my $25.00 each
	Phillips tubes).

								Jens

    Is it REALLY REALLY important to have the thing biased each time you
    replace the tubes?  I'm talking 'bout using the same make and kind of
    tube. 

	There is an adjustment on many power amps that can be made with
	a screw driver. This is used to adjust the HUM down to a minimal
	level. I just use my ears for setting this. I havn't made an
	adjust ment of this nature in a long time (you don't even have to
	take anything apart, as long as you can get to the adjustment).

	Unless you change tube type (ie EL34's -> 6L6GC's), you really
	shouldn't have to do anything (I don't recall tweeking anything
	on My Twin Reverb in the last 6 years (as long as I've owned it),
	or ever tweeking anything on the Fender Bassman that I had for
	at least 10 years before that).

								Jens

    
    Hey Boom/Steve G., is that a hum adjustment on the M1 power section?  
    You know the one that can be adjusted from the top (w/ chassis removed) 
    with a screwdriver?

    Saturday I decided it was time to replace the tubes in my Ampeg B25-B
    bass amp. Hey, after 17 years and tons of gigs the originals didn't
    owe me any money!
    
    Ouch. Admittedly I didn't shop around, but just went to my local dealer
    who generally takes care of me. The price was about what I expected for
    Groove Tubes so I didn't flinch....
    
              2    7027A      $40
              1    5AR4       $25
              2    12AX7      $30
              1    7199         4.80 (RCA)
                             -------
                               99.80
    
    Ya know, I didn't pay a whole lot more than that for the entire head
    *brand new* back in '73!!
    
    Edd

      re .67 - I believe that pot is for fine tuning the bias. I know
    the old routine of hum/balance from my old Ampegs. I'll let you
    know next time I change tubes. To be totally honest I shouldn't
    have to change tubes that often since I use my KH/SGE/SP rack
    about 95% of the time. I use the M5 for practice. 
      I have a few jobs coming up for the M1 stack though. That's when
    I want to get a good picture for the guitar notes photo album.
    							
    						--|bOOm|--

    Well, I ordered and just received a set of four 6L6's for $7 each from
    Prosound in Colorado. These are the SOVTEC tubes made in the Soviet
    Union. I ran 'em up at practice the other night and you can count me as
    one highly satisfied individual. The tubes have an even glow, which may
    or may not mean anything; its pretty though. The amp (Fender Super Six)
    honks!!! Very noticeable difference, and I used to think that tube
    changes were so much bullsh*t unless it was a hard failure. 
    
    "Sakman" who is canceling his subscription to Guitar Player since 
    becoming a follower of this notes file. 

    re .67
    
    Sorry I'm late getting back to you, but the project I'm working is going
    down the toilet and I haven't had much time to get into notes lately.
    
    Anyhow, Boom is right, that pot is a bias adjustment which can be used
    to equalize unmatched tubes.  It doesn't adjust 'hum balance'.  The
    100 watter has two of them... one for each pair of tubes.  I used to
    have an amp (Fender Concert) that had both the bias adj. pot and a hum
    balance pot... nice feature... if it only sounded as good as a kitty..8^)
    
    Steve

    	Well, I need some information on "tubes gone south"... 
    I have an Ampeg V4B amp head and a FIRM belief at least
    one tube has gone south on me due to an incredible high
    pitch when trying to turn up past a certain volume level.
    My questions being, how do I tell EXACTLY which tube(s)
    have gone south. I was contemplating replacing ALL the tubes
    but after reading .68 and considering my current financial
    status, have decided to replace the trouble tube first and
    ordering the rest. In time that is...Best way to contact me 
    is VAXMAIl...
    
    MSBOS::PELLETIER
    
    Thanks,
    
    Steve...
    

    1. Try tapping the tubes (gently!) with the volume turned up some,
    if you here the tapping through the speaker the tube is microphonic and
    should be changed.
    2. If you don't find the bad one this way. Buy one each 12ax7 and
    12au7 (I think those are the preamp tubes in v4) and try changing
    the preamp tubes out one at a time until the noise stops. 	
    	The power tubes (7025's) are very unlikely to cause this sort
    of problem.If you change those or their drivers you should check the
    amp set-up.
    
    	My guitarist uses a V4 into an old Marshall cab. Its loud and
    sounds great, but if he puts the head on the cab, he gets the same
    sort of thing as you discribe. So as that old joke about:
    
    	"Doc, it hurts every time I do this"
    
    	"Then don't do that!!!"
    	
    	So he leaves it on the floor, figures it will make the tubes
    last longer...No mechanical stress.
    
    	BTW I love my SVT!!!!(except when I retubed it)
    

    	re .73
    	
    	I'll check them out and I managed to find a couple of spare
    	12ax7s in an old amp buried in the cellar. I did some swapping
    	and seems things have "mellowed". I will try putting the amp
    	head elswhere cause I have changed the speakers. I took out
    	the Ampeg 15"s and put in a pair of JBL K140 series low freq.
    	and it gave it a nice sound so I may have induced the problem
    	on my own... Next, you mention 7025's in your reply. I have an
    	ancient Univox Big Blue amp head that I fried last summer and
    	after $150.00 and two visits to the repair shop I gave up on
    	it. I think I found the problem the other night in the swapping
    	of tubes and it seems one of the 6clc's/el34's has a short in
    	it and arcs out continously blowing fuses. BUT, this is not
    	the main jist of this questioning regarding 7025's. What it
    	is that I'm questioning is that the 12ax7's that are supposed
    	to reside in there have been replaced with 7025's. IS this a
    	good idea?  Any information along these lines will be appreciated.
    
    	Steve_who_likes_tube_amps_but_not_the_repair_shops...
    

    	Sorry I was thinking that the 7025's were the power tubes. I
    forgot my mind at home yesterday. 7025's and 12ax7's are replacements
    for each other, interchangable, etc. I think that the only set up
    on a V4 is the hum balance. Ampeg was always go for putting the
    set up procedures right on the chasis, so if you got the amp you
    got the adjustment procedure.
    

    oh, you musta meant the 7072a's. the BIG guys... okay,
    now I know somthing about what I'm talking about. Phew,
    what a relief. Thanks for all the info. At least now I
    know which direction to head to try to resolve my tube
    troubles. As for locating the tubes I'm gonna need, well,
    the Radio Shack I called yesterday in Searstown told me
    they don't stock tubes anymore. Nash Electronics said they
    could oreder the tubes for me, if I wanted to pay $30. a
    piece. Na, let me make a few calls and I'll get back to ya.
    Still looking and waiting for my Allied Electronics Cat. and
    my MCM catalogue. 
    
    Tubified...
    Steve G.

    okay, so I don't have the numbers right either, 7027As.
    ANYWAYS, still looking for a 6CA7/EL34. the Ampeg is
    back in commission but I'd like to get the ol' Univox
    back in working condition. I'm hoping that is all it
    needs, any more than that and it's scrap...
    (maybe I can use it as a nightstand?) HA!
    
    Thanks for the help...
    
    Sp

    re:1240.21  (a long time ago.... )
    
    The new Mesa 400+ Bass head uses *12* 6L6's!!!!
    I couldn't afford to retube that monster with Mesa tubes!!!!
    
    Hmmmmm...  maybe if I take out a loan....    ;^)
    
    
    
    Fred

    Now you can get that vintage blues sound you've always wanted.
    We're talking "the" sound of the early Fender Tweeds.
    
    	Here's how you do it:
    
    		Buy some off-the-shelf, unmatched, Sylvania or RCA
    	tubes and save a bundle of $$.
    
    	After all, there was no MESA/Boogie back then.
    	No Groove Tubes.
    	No Audio-Glassic.
    
    	joe.

    
    Except Sylvania and RCA don't make tubes anymore.
    
    8^)  8^)  8^)
    

    re .79
    
    good point joe.
    
    re. .80
    
    sure about Sylvania?  I was positive I had bought some last year.  
    mebbe not, eh?

	But there's a lot of the tubes still comming out of hiding...

	It appears that Phillips is manufacturing tubes in the US. I
	bought one to replace the chinese junk the mexicans stuffed
	in my champ12 before putting the Fender mark of approval on it...

	I shelled out the bucks for a duet of boogie tubes a few weeks
	back cuz the Fender tubes in my 60 started wispering in martian.
	No way could I afford to spring for the GTs.

	Hey SAKMAN - how're them SOVTEKS holding up?

	ccb

Yeah I just bought a fistfull of Sylvania 12AX7A's...

dbii

    
    Oops.  The 6L6's I bought were Phillips - not Sylvania.  A mind is 
    a terrible thing to waste...

    re:82
    
    Yep, the Sovtek tubes do the job just fine thanks. I was curious as to
    whether I would really hear the difference. I wondered if the tube
    change philosophy was for the purists with extra $ who confirmed the
    placebo theory. I wonder no more, the tubes definately make an audible
    difference. I'm not sure if the audience notices it, in fact i rather
    doubt it. But I do and I guess that's what's important.
    
    Now I'm not sure if the sound improvement is due to the fresh tubes or
    the fact that they're Sovtek. I would like to try a side by side comparison
    of tube manufacturers to see if there is a difference between them. I
    doubt theres an audible difference. Agian I'm sure the Audience
    wouldn't notice it. In fact, ever notice that your equipment sounds
    different when playing in a band than just dubbing around at home? 
    Anyway, the Sovteks work just fine, I'm glad i took the chance on 'em.
    At $7 each, I shoulda bought a case!
    
    "sakman"

    Anyone try the TNT tubes being offered by Stewart-MacDonald?
    They did have Groove-Tubes, but that lasted for 1 catalog, and they
    came up with these.

    see note 396.18 for Groove Tube info and also their Tube book
    
    Paul

    Does anybody know anything about Ruby Tubes? Stewart McDonald's has
    them, and 12AX7's go for about $6 apiece if you buy 6 or more. That
    seems like about half the price I've seen tubes anywhere else. I'd like
    to restock my amp (which uses 5), and I was wondering if these are a
    good deal.
    
    - Ram

    Ram,
    	Ruby seems to be a distributer for a few different brands, kinda 
    like GT's I guess. The Ruby 6L6GC's are (as far as I know) Solvtek
    tubes with the RUBY logo on them. I would guess that since most 12AX7's
    are *basically* the same, I'd go for it. I really don't think the quality
    will be much different from Peavey and Mesa tubes either and if you
    can save a few bucks along the way...  why not. In MESA's however the
    V1 position tube is the most important position for the best tube you
    can get, so in my rig I spent the BIG bucks for that SP?A?X?? tube that
    has the shrink rap around it and 90% of the wierd sounds went away, but
    as for the rest...  I'd put in the RUBY's if I had to replace them.
    FWIW, I have Solvtek's in my PV-MX rig and I really like the tone. When 
    it's time to change the Mesa tubes...  it'll be Solvtek (aka Ruby) for 
    that rig too.
    
    			Go for it Ram!
    
    				Rock on,
    					Fred

    I bought some Ruby power tubes once (6V6s).  They were from China,
    said so right on the box.  The interesting thing about these were
    the glass bottles were opaque black.  Kinda weird, you couldn't
    even see if the tubes glowed when on.
    
    I don't know if everything Ruby sells is Chinese, but if these
    are then beware.  My power tubes are okay, but I have been reading
    bad things about Chinese preamp tubes in general; i.e., poor tone and
    low reliability.
    
    /rick

    
    Does anybody know where I can find a tube tester?  I am interested
    in determining which tubes I have are good/bad so I can sort thru
    the spares.
    
    Thanks,
    -pat

    You've already got one ... the M1 ... 8^)
    
    
    Scary

RE: Pat

Almost all RadioShacks have 'em...  But Jerry has a point too.
Those testers only test for continuity and signal flow - they don't
test for sound quality...  I've plugged in absolute CRAP power tubes
which tested "Good"...These were tubes that made my buddies Marshall
run with NO volume (Hey Greg, remember those tubes we pulled out of
Toms Marshall ?? - Bleck!)

jc (With no faith in "Tube Testers")

>    These were tubes that made my buddies Marshall run with NO volume (Hey
>    Greg, remember those tubes we pulled out of Toms Marshall ??
    
    THOSE tubes tested good??  They were the absolute worst I've ever
    heard/seen!
    
    Greg, who can attest that these tubes were totally fried

Yep, those tubes are the ones.  I brought those to see if what I'd
heard was true.  Eeeek!

>>    I bought some Ruby power tubes once (6V6s).  They were from China,
>>    said so right on the box.  The interesting thing about these were
    
    My Ruby 6V6s are "normal" glass tubes (I bought them about 8 months
    ago).  I stocked up from Stewart MacDonald-- 3 pairs of 6V6s and
    a slew of 12AX7s and AT7s.  I've been very pleased with them --
    great sound and low noise at less than half of what music stores
    around here charge for Groove Tubes.  Tubes seem to be the luck
    of the draw no matter where you buy them.
    
    I've seen Westinghouse 6V6s that have the opaque glass like the
    ones described in .90.
    
    Jim