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Conference napalm::guitar

Title:GUITARnotes - Where Every Note has Emotion
Notice:Discussion of the finer stringed instruments
Moderator:KDX200::COOPER
Created:Thu Aug 14 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3280
Total number of notes:61432

3170.0. "Question on tube amps and active p.u.s" by USCTR1::pelkey.ogo.dec.com::pelkey (professional hombre) Tue Feb 06 1996 14:13

now, I feel should know this,. but I've got
a few burning questions to run by yous
guys...


What's the deal when using a guitar with
active pickups and a Tube amp ???

Do the active pickups stress the tubes out
more than non active ?  (I'd almost assume
they would...)  should this be something I
even need to think about ? (Love the active
pickups for fattening things up!)


Also, when using exptension spkr cabs, should
the amp be shut off when attaching/disconnecting
the extension cabs, or is standy o.k.  (I'd
always assumed that STANDBY killed the power
to the speakers, but now that I've got a tube amp
with a standby, i'm wondering...)  Also wondering
if switching the impedance while the amps running
could be a problem...


All precautionary questions mind yous.. discuss
freely...

after haviong solid state for ever, I guess I'm
slightly paranoid.... don't wanna fry the JTM60
ya know.


T.RTitleUserPersonal
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3170.1CTPCSA::GOODWINTue Feb 06 1996 14:2015
    
    Standby is o.k. for disconnecting/reconnecting speaker cabs,
    but wait a few seconds after switching to standby as it takes
    time for voltages to bleed off the caps.
    
    Switching impedance while amp is on could cause major league
    problems,  but should be o.k. to do in standby mode.
    
    I'd also guess that active pickups could more readily overdrive
    the first stage input tubes, but who cares?  If it gives you the
    tone you're after, why worry about replacing preamp tubes more
    often?
    
    /Steve
    
3170.2OCTAVE::VIGNEAULTMinister of chilesTue Feb 06 1996 14:259
    
    Try it and when it fries, I'll take it off your hands cheap :^)
    Actually, what have you got to lose by powering it off to do 
    the things you described.  When you set up your rig, make sure
    all settings are right, then turn it on. Done, no risk. My PV
    cab has a warning about switching the impedance while the amp 
    is powered up. Says it could damage the speakers. 
    
      Lv
3170.3USCTR1::pelkey.ogo.dec.com::pelkeyprofessional hombreTue Feb 06 1996 14:4736
Yea, once I toast it, I'll sell it real cheap,
like 500 bucks maybe...


The reason I've asked the question is,
since i've just added the extension cab, I was 
shutting it off changing the config to see what  
the difference in sound was...   (Fatter with
the extension cab, of course,, I knew that)

Then I thought, this is silly, why not just do
the standy..  (again, assuming this cuts the heat
to the speakers..)

But then it got me thinking about it in general
so I thought I'd ask..  I'd have assume the damage
would have been to the amp, but I read here it's
actually the speakers that are suspect to damage,,
see!  'I did not know that'

But yer right, for the most part, it's not an issue,
cuz primarily, the extension cab is either there when
I juice it up, or it's not...  (most of the time,
it'll be there..)  just wonderin...

anyhow, as far as the active goes, I woudln't assume
it'd be a tube killer, besides, I'm really not 
maxing out the level on the guitar's preamp, just
adding a little to add some more beef.  (As if this
thing needs more beef,,,  these Marshall JTM60s
honk for small portable combos boys..  The 'marshall'
sound, and no trucks or dollies needed.. way cool)

Thanks kids..

/r
3170.4OCTAVE::VIGNEAULTMinister of chilesTue Feb 06 1996 15:0713
    
    The active electronics are the same as having another preamp in the 
    circuit I would think.  Since the amp is getting a hotter signal,
    you probably wouldn't need to crank it as much as you would to get
    the equivalent sound without the active electronics.  In the end, 
    I don't think it makes a significant difference as to the life of 
    the tubes.  If the standby switch basically isolates the speaker
    output as if the amp were turned off, then I don't think it's a
    big deal to plug/unplug the speaker cabs.  Only when you have some
    sort of output sitting there would it pose a problem.  I'm not the
    definitive expert on these types of issues however.
    
      Lv
3170.5USCTR1::pelkey.ogo.dec.com::pelkeyprofessional hombreTue Feb 06 1996 15:1817
well, you'd have to have a few bolts loose to
start going after speaker jacks with the amp
cranked up anyway...

Good thing it takes two hands (for most) to
play guitar aye Larry..  Keeps you out-a trouble!

I think were all pretty much holding the line 
on the preamp..  Don't really think it could harm
anything,, again, just a question of sorts...

I know that on the older rockmans, active pickups
use cause some problems.  

So Larry, gonna be amp shopping ??????


3170.6OCTAVE::VIGNEAULTMinister of chilesTue Feb 06 1996 15:249
    >> So Larry, gonna be amp shopping ...
    
    It'd be nice to have another amp to play with, but my wife won't buy
    into it.  Someday.  The autobiasing feature on your amp, as well as
    the availability of replacement tubes in a kit package are attractive
    since my biggest hassle with tube amps has been replacing the damn
    tubes.  I especially like the autobiasing, nice feature!
    
     Lv
3170.7JARETH::KMCDONOUGHSET KIDS/NOSICKTue Feb 06 1996 16:3815
    
    
    I've been using onboard preamps on my guitars for years and I've never 
    noticed any shorter-than-average tube life.  This is with both a Twin
    and a Marshall JCM 900.  My guitar can drive headphones, so I've got a 
    *lot* more kick than the standard guitar.
    
    If I'm using a clean setting with a lot of headroom, hitting the 
    preamp makes it much louder in a hurry.  For a high gain setting, I get
    even more gain, pushing the amp pretty hard it would seem.  I played
    the Twin like this for 10 years without a problem, and I'm probably 
    4-5 years into the Marshall without any trouble.
    
    Kevin
     
3170.8USCTR1::pelkey.ogo.dec.com::pelkeyprofessional hombreTue Feb 06 1996 16:556
I like the sound, and like I said early, Van and helpers
not required...

Aye-yup..

/r