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Re: Guytron GT-100 (Radical new design for tube amps?)

12/12/1997 11:42 PM
Jim Kroger
Re: Guytron GT-100 (Radical new design for tube amps?)
There is one in the shop near me, I'm going to  
have a look.  
Sorry to ask a non-guytron question, but how  
DID Mesa change amp design? This gets at a  
question that has bugged me for years.  
12/13/1997 10:07 AM

Mesa is given credit for adding an extra  
few gain stages, thereby generating  
that Santana sustain for ever sound.  
They brought controlled, lower volume  
distortion/sustain to the masses.  
At least, that's how the story goes.  
I'm sure there were others doing that  
around the same time, or earlier, but  
Mesa got Carlos to make it famous and  
the rest is history.  
... Whit
12/14/1997 12:08 AM
Steve Ahola

    Whit answered your question, but since I made the original statement, I thought I better clarify that I was referring more to marketing and R&D at the major amp companies, than to actual amp mods and design. Randall Smith wasn't the first nor the only amp tech modding amps back in the 60's. On Harvey Mandel's first album (released in 1968), Charles Button of Don Wehr's Music City was given credit for the custom engineering of Harvey's guitar amp. Talk about endless sustain: there are notes on "Wade in the Water" and "Lights Out" that seem to go on forever!  
    I had seen guitarists in the 60's plugged directly into Fender amps getting more distortion and sustain than you would expect from a stock amp (or even one that had been tweaked a bit with hot tubes and more gain). Not knowing anything about tube circuits, I suspected that they had a fuzz box hidden away inside their guitar or amp... Why the heck would they want to eat hot dogs when they could have a real steak? I'm sure that many of the guitarists back then had customized amps with extra gain stages, only they tried to keep it a secret so that the audience would think it was their technique that produced those tones...  
    Mesa Boogie was influential in that they made amps with extra gain stages on a production line and were sold in stores (and happened to become very popular thanks to Carlos Santana).  
Steve Ahola
12/14/1997 8:06 PM
Jim Kroger

Thanks to both of of you for clearing that up for me. I didn't know of the Santana-Mesa  
Is the difference that Mesa provided  
a master, which permitted the preamp  
stages to be pushed into distortion  
while keeping ouput current down,  
or that they put in more gain  
I know very little about electronics  
so please excuse any dumb misconceptions.  
12/14/1997 9:09 PM
Jim S.

By itself, the master volume (inserted between a vintage-type "clean" preamp and the power section) is not going to yeild that infinite sustain tone. You need to add significantly more gain.  
Interestingly, the first production model Boogie, the Mark I (which Santana still uses - he never liked the later Mark series) has a circuit that is remarkably close to that of a Fender Twin Reverb. The high gain input jack routes the guitar signal through only one (!) extra gain stage before the rather conventional Fender blackface style preamp configuration. Some additional gain capability comes from the fact that there is only a single channel (therefore no signal loss through passive channel mix resistors) and that the drvier/phase inverter tube is the higher gain 12AX7 instead of the Fender's 12AT7.  
Although I haven't tried this, it would be relatively straighforward to convert any two-channel Fender blackface or silverface combo into a Boogie Mark I circuit.  
By today's standards, the orginal Mark I is not a super high-gain amp. In order to get it to really sustain, you need to crank it to some degree. Again, the ultimate tone comes from a combination of preamp gain and power amp saturation (along with working the speaker hard).
12/15/1997 4:00 AM
Jim Kroger

Thanks much, I appreciate the info. Think  
I understand the Boogie thing now.  
Mark I's seem hard to find. Everyone else  
must feel the same way.  
12/16/1997 9:28 AM
Pat F

Jim - I'm a big Boogie fan, and built a homebrew amp based on an early Mark I schematic I have, but I left out the graphic EQ and reverb. As one of the earlier posts mentioned, the original Mark I was pretty much a standard Fender type preamp, but with an extra gain stage in front of it. Mine screams. My personal preferance is to play it through a single EV12L cabinet. I do get sustain forever and that is with the Master at 2. In high gain mode, it is increadibly loud. Anything past 3 and things start falling off the walls. Much of the info I have about the early days of Boogie is anecdotal and I don't claim that it is gospel, but here is what I've heard. Supposedly Carlos Santana stopped by Randy Smith's shop in Haight Ashbury. Randy had, as kind of a prank, hotrodded a Princeton that had been dropped off for repair by a guy with Country Joe and the Fish (Melton?).  
It was essentially a Princeton cab and chassis with a 12" speaker, 50W power and output transformers, set up like a bassman with the extra gain stage. Carlos started playing with it, and allegedly said "this little amp really boogies". That is how the name was coined, at least based on the account I read. I had also read that Lee Michaels had something to do with the early development of Boogies. According to some lore, many of the early Boogies were Princetons and Deluxes that Smith bought, gutted and rebuilt as Boogies. After a while Fender got wise and cut off his supply of transformers that he was purchasing from them to make Boogies. I guess they didn't want to supply their competition. There seems to be IMHO a love/hate thing with Boogies. Some guys hate the preamp type distortion they produce, and some of us like it. I guess it depends on the music you like. Well I've gone off an a tangent here, but I couldn't resist tossing in some folk lore here.  
Pat F.

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