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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

1834.0. "Overdrive: The Preamp vs. Power amp stage" by ICS::BUCKLEY (She's breakin hearts in Heaven...) Wed May 23 1990 14:28

    I've been experimenting and reading a lot lately about tone and 
    overdrive.
    
    Now, I know there is a generic preamp note, but lets not confuse this
    issue...this topic is about the difference (in an amp top) between
    preamp saturation and power amp section saturation!
    
    A lot of big cats (Steve Stevens, Ronnie Le Tekro, Malmsteen) express
    the view that to get TONE, you need to have some sort of power section
    overdrive happening.  They believe that you get a lot of buzz n fuzz
    from the preamp section, but not a lot of tone.  This prompted me to
    crank the master volume on my amp to 10 and then start tweeking the
    tone and preamp controls.  WOW...lemme tell ya its a different world
    out there kiddies!  With my Master volume down low, the amp acts and
    sounds 100% different...it sounds much bigger, rounder, warmer, and
    full with the master on 10 and the other controls more moderate.
    
    On my 2205 head, I use the volume and gain controls on about 5 and 8
    respectively in combination with the master section on 10 to get a
    really nice tone!  When I had my Carvin 100 watter, I found the same 
    thing...running the power amp stage into slipping really makes for BIG 
    notes (no, not loud notes, big notes...you'd have to try it to see what
    I'm talking about).
    
    Anyone else have comments about the differences of preamp distortion
    to power amp distortion?  Anyone else care?
    
    Buck, playing a tad louder these days, but definitely with more TONE.
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1834.2FREEBE::REAUMEjustanuthashitheadonpatrolWed May 23 1990 19:5410
      re : the last two comments-
    
      And that's why you can run a Kitty Hawk M1 in class A mode (which
    is 30 watts) to get power amp crunch at a reasonable volume. If
    you need more power then I revert to class AB (back to 100 watts).
      And that's why I like my SP-1000 power amp in the rack, because
    it sounds VERY tubey when cranked.
    
    							---/boom/---
    
1834.3Sometimes less IS moreBSS::COLLUMOscar's only ostrich oiled an orange owl todayWed May 23 1990 21:226
    re .-1
    
    Same thing with my Boogie Simul-Class.  On Class-A (15 watts), it has
    a special sort of tone.  Kick in the Class-AB to get a bit louder.
    
    Will
1834.4more or less in the same veinFREEBE::REAUMEWEEKENDworkweekWEEKENDworkweek...Thu May 24 1990 20:0214
      Remember all the hoopla about the Rockman "Power Soak" giving
    you all that power tube overdrive. Remember all the power amps
    going PPFFFFFTT! I know there are still people that use them,
    but that's how I cooked my old Ampeg V-4. I guess if you used
    a power soak in moderation it might not be that bad.
      Then there's always the good old Variac approach. I've never
    even entertained that option. Seems to me like a way to go
    PPFFFTTT louder than a soak, and it increases your overall
    volume anyway.
      Then there's the price of replacing power tubes....
    Since I primarily use my rack I don't have to really deal
    with that too often. 
    						----/boom/----
    
1834.5Even if they're dangerous, they get you a cool tone!COOKIE::G_HOUSEThu May 24 1990 20:1914
I used to use a PowerSoak for exactly that and never had any problems with 
the amps I used it on.

I was just talking to a friend about that yesterday and he said he used one 
on his Marshall for *years* with no noticable side-effects, and he said he 
played it three to four days a week for several hours at a time.  He said he 
just had to replace the power tubes a little more often.

I don't want to start any arguments, if any of you had an amp blow up when 
using a PowerSoak, but I have to wonder if some of the failures weren't 
due to user error, like not correctly setting the impedence on both the 
PowerSoak and the amp.

Greg
1834.6BSS::COLLUMOscar's only ostrich oiled an orange owl todayThu May 24 1990 21:355
    Greg,  you gonna unload that PowerSoak with the HiWatt?
    
    It's a match made in heaven!    ;^)  ;^)
    
    Will  (who's wondering where J-dot is lately?)
1834.7MRVAX::ALECLAIREFri May 25 1990 14:4621
    On my MLV 100W I pretty much stick to 2 tones:
    Preamp 10, MV <1	this gives a pretty much  consistant distortion
    		^ here the master volume is tweaked ever so little,
    		I try to find the point where I can hear the Power tubes
    		kick in. I't real delicate, but there's for sure a point
    		where you can hear them kick in
    
    Preamp  2  MV  2	This and higher   2><4 on the MV give me control
    			of the distortion at the finger, when I play real
    			light there's no distortion, but when I pluck the
    			string with any force it goes to distortion.
    			This is nice, to have distortion at the fingertips
    
    Neither of these settings are real loud, since I play in a room which
    is VERY live.
    
    The last Time I tested the thing for volume, I noticed the tone seemed
    to stay pretty much the same over 4 1/2 (MV). And the change in volume
    was greater from 1-4 than 6-10.
    
    to
1834.8Difference explained?ELESYS::JASNIEWSKIThis time forever!Fri May 25 1990 15:0045
    
    	Well, there actually is a "scientific" reason for this differance!
    A preamp is, and this is *all* preamps I believe, contructed as a
    cascaded single ended structure. That is, each stage of amplification
    is followed by another stage - and another and another in some preamps
    - which gives the "cascaded" part. The "single ended" part means that 
    there is a single active element - be it a regular transistor, an FET 
    or a triode tube stage - at each stage of amplification. Each kind of 
    active element distorts differently, making a different "tone", which 
    is why there's "tube screamers", "real tubes" "FET overdrives" etc et al.
    
    	In a power amp stage, the single ended structure changes at the
    so called "phase splitter" tube. From this tube on, the structure
    is now known as "differential" because there are *two* active elements
    for each stage of gain. Most amps only have the power amp tubes
    after the phase splitter, but some designs will have an extra stage
    of triode amplification.
    
    	The thing that makes the big difference in how it sounds is
    - and this may be a little hard to comprehend - what happens to
    the distortions from each of the two elements of the differential
    amplification stage when the signals get combined in the output 
    transformer. The two distortions get algebraically subtracted from 
    one another, which means that the even ordered harmonics cancel one 
    another. (This does not and cannot happen in a single ended preamp
    design, no matter how many stages of gain there are) 
    
    	As we all know, the way something sounds is completely determined 
    by the harmonic content of the sound we hear. If we hear a sound that 
    happens to have all the even harmonics supressed, it will be very
    distinct and very identifyable. We like to place subjective terms
    on how something sounds and the chosen one for this type I believe
    is called "crunch".
    
    	Now here's a hint for all you would-be enterpreneurs out there.
    Build a preamp with the very first stage being a phase splitter,
    and do all your subsequent amplification via differential stages.
    Include two or three interstage transformers in the signal path,
    so that the distortions from the elements comprising the differential
    amplification stages get processed accordingly a few times as the
    signal goes through the preamp. I'm sure this would be a "winner",
    because you could obtain the "cranked power amp" sound without the
    noise, a "power soak" or running big expensive power output tubes.
    
    	Joe Jasniewski
1834.9Soak it upCOOKIE::G_HOUSENo, I'm very, very shy.Fri May 25 1990 15:1116
> Greg,  you gonna unload that PowerSoak with the HiWatt?

If that makes the difference to someone in selling it, sure!  But I'm using 
it to do impedence matching so I can run all my speaker cabinets concurrently
off the Kitty Hawk right now...

;^)
    
> (who's wondering where J-dot is lately?)

He normally works late in the week and weekends, but he had an automobile 
accident last weekend and has been out a few days.  You'll probably be 
seeing more of him back in here now that he's feeling better and has
purchased a new car.

Greg
1834.10RAVEN1::BLAIRNever met a guitar I didn't likeFri May 25 1990 17:184
    
    re: .9
    
    Is J. O-K?
1834.11TCC::COOPERMIDI rack pukeFri May 25 1990 18:574
He was logged in last night, so I guess he's okay.  No serious
injuries from what he posted in HEAVY_METAL, a few cuts and scrapes.

jc
1834.12BSS::COLLUMOscar's only ostrich oiled an orange owl todayFri May 25 1990 19:589
    re .8
    
    Nice write up!  I understand it, but I would have never thought of it.
    
    re Greg,
    
    Wow, give my best to J-dot.  Glad he's OK.
    
    Will
1834.13Except for that "brain disorder" that the accident didn't cureCOOKIE::G_HOUSENo, I'm very, very shy.Fri May 25 1990 20:025
Yes, J's fine.  I just got back from having lunch with him.  He's back at work
but is probably a little behind on Notes.  I expect you'll start seeing him 
again soon.

Greg
1834.14Play louder, get more toneICS::BUCKLEYShe's breakin hearts in Heaven...Wed May 30 1990 14:3312
    Did a lot of reading on my plane trip to CO this past weekend.
    
    Eric Johnson, a tone MASTER, firmly believes the only way to get 
    "the 100lb violin lead tone" is to have a Marshall head with the 
    volumes to 10.
    
    Blues Saraceno 2nd this opinion on obtaining the perfect lead tone, 
    but using Laney heads.
    
    as did Ritchie Kotzen, the guys from Kix, and several other guitarists.
    
    Are tehy telling us something guys?
1834.15DNEAST::BOTTOM_DAVIDNice computers don't go downWed May 30 1990 16:066
15 years ago or more I felt that overdriving the power stage was the only
way to get serious 'tone'

fwiw

dbii
1834.16DECWIN::KMCDONOUGHSet Kids/NosickWed May 30 1990 17:0033
    
    
    I've always been happy with the sound I got from driving the preamp
    section to the brink and adjusting the master volume to taste.  This is
    especially true with amps like KH and Boogie that have lots of gain to
    begin with. 
    
    
    I do think that every amp has a volume threshold that you have to cross
    to get the best out of it. I don't know if it's the point where the
    speakers really start to breathe or whether the power stage has to
    reach a certain level before it all comes together. 
    
    Cranking the power stage to 10 and then bringing up the preamp volume
    has never done it for me.  Too clean, and it usually gets too loud before
    I'm happy with the tone. 
    
    Unless I also bring the preamp volume to 10, that is.  8-)   Some
    Fender amps are like that to me.  They like to be driven hard! For
    large rooms, I used to run my Fender Twin wide open, with the guitar
    preamp CRANKED.  What ever headroom there was in that preamp was put to
    good use.  Sure it was wicked loud but man, what a sound.  It sounded
    more Marshall-like than Twin-like. 
    
    A friend of mine used to use a 50 watt Marshall, as opposed to a 100
    watter,  just so that he could run it wide open. 
    
    Maybe the answer is to get an old Pro Reverb, give it a real hot
    signal, and stick a mike in front of it.  Hmmm, isn't there a "Play
    with small amps" note?
    
    
    Kevin
1834.17yep....RAVEN1::DANDREAFrog lickers unite!Wed May 30 1990 17:298
    It's been said many times before.....if ya likes that "classic" rock
    tone, there isn't much better than an old Les Paul runnin' thru a tube
    amp wide friggin open.  I had a buddy in Colorado that used a 50 watt
    Marshall and a Les Paul with no effects.  He ran the amp on about *8*
    and it sounded wunderful....but I guess I'm old fashioned anywho!  I be
    likin' my KH M3 100 watter/PV 4x12/Les Paul, even tho I'm "retired".
    
    Steve D.
1834.18Everyone Knows A Princeton Is The Ultimate AmpAQUA::ROSTI'll do anything for moneyWed May 30 1990 18:035
    Re: .16
    
    Note #1339 is on gigging with small amps.
    
    						Brian
1834.19VAXWRK::SAKELARISWed May 30 1990 18:409
    re: last couple of entries.  I might have agreed with these until I
    heard this new overdrive device. I just wrote about it under the
    Generic Guitar Preamp topic. 1819.54 I think.
    
    But then again, I think they're gettin pretty good with these external
    devices these days. At any rate, one thing is for certain, tone - my
    ass; the audience ain't real appreciative of a Marshall set at 10.
    
   "sakman"
1834.20You have no choice but to read my lipsMILKWY::JACQUESIf you don't stop, you'll go deafThu May 31 1990 16:4614
    .19 made a good point. No audience will appreciate your tone (no
    matter how sweet) if it is too loud. If you play small clubs, and
    subscribe to the theory that only power amp distortion will do,
    get yourself a 30 watt amp and save your Marshall stack for the
    Centrum.
    
    Nothing will draw complaints from the crowd faster than playing
    too loud ! In a club setting many people are not just there for
    the music. They want to socaialize, and if the band is too loud,
    they can't hear themselves think, and can't converse with other
    people.
    
    Mark
    
1834.21Gatton ripped me head off!ICS::BUCKLEYShe.....malaria!Thu May 31 1990 16:554
    -1
    
    Tell that to Danny Gatton...he plays MUCH louder from his Fenders
    than Blues did from his Laney!
1834.22GOOROO::CLARKJust say NO to Sterling Downs!Thu May 31 1990 18:234
    re .-1
    
    yeah, but it was all high-end. Everything above 2 Khz was boosted about
    30 db. Not too loud, just too bright!
1834.23KIDVAX::ALECLAIREFri Jun 01 1990 16:3611
    I thnk anybody who runs Marshalls at 10 is nuts.
    1. PERMANENT hearing loss
    2. I've had them up there for short periods and don't see much of a
    diifference between 6 and 10, and even 6 is pushing it.
    3. Who cares what Jimmy Guitar Hero says? 100W marshall for crispness
    running a hot input on 1/10, 2/8 sounds the best for normal listening.
     
    I still don't buy this 10 balogna.
    And NoBody can duplicate the sound of a Marshall, it just don't sound
    the same.    
    
1834.24UPWARD::HEISERkneeling at the altar of painFri Jun 01 1990 20:294
    I've never played through a Marshall, but "green mode" on Kitty M1
    comes CLOSE to a lot of the Marshall recordings I have.
    
    Mike