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

12/10/1997 2:16 AM
Steve A.
Guytron GT-100 (Radical new design for tube amps?)
  The January issue of GP reviews the Guytron GT-100 head, which has some very interesting features that may turn around amp building (like Mesa did in the 70's). The preamp drives a pair of EL84's (in Class A) which goes into a small output transformer and a dummy load, before the signal is routed to the output stage using 4 EL34's. With this design, you can get very authentic overdriven sounds at lower volume levels. When cranked up, the initial output tubes and transformer will mellow out the distortion from overdriven preamp stages (without having to add caps and other circuitry that swallow the tone and definition). Sounds like a great idea to me!  
  It seems like the amp builders here could come up with something along these lines at a fraction of the $1,995 price tag for the Guytron. Of course, I could plug my Peavy Classic 30 into my Marshall Power Brake set to 0% output and run a line level signal from a HK Red Box into the main amp input of another amp, but I don't think it would sound quite the same...  
Steve Ahola
12/10/1997 7:20 AM
Re: Guytron GT-100 (Radical new design for tube am
I might use two EF86's in class A at 100mW...
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12/11/1997 3:12 AM
Dave Harris

What are you going to use for the transformer and load ? I have the EF86s ready and waiting..
12/11/1997 10:17 AM
I found a 20K:4 ohm 200mW output transformer in the Circuit Specialists catalog for $1.69 that I thought I'd try. At those power levels, you could put a real speaker inside a fiber fill packed box and just run a speaker for a dummy load.
12/11/1997 10:53 AM
Dave Harris

Do you think it would sound "authentic" ? as Doc says..  
"It's the actual sound that our ears hear from the speaker that completes the equation. The only way to get authentic overdriven speaker sounds is to mike the speaker."  
It must be worth a try at any rate as I have almost given up on pre-amp distortion and fuzz boxes (sorry). I usually just turn up. The opinion poll is heading that way too but who wants to take a bunch of amps to each venue ?
12/10/1997 10:30 AM
Dave Harris
Re: Guytron GT-100 (Radical new design for tube amps?)
It will only sound authentic if they get the design of the dummy load to look like a speaker. I have tried an AC30 output stage into a resistive load and then into a power amp and speaker and it was not so good. It was a lot better with a speaker load. I put the AC30 in one room and ran a feed from the speaker into another room through a SS power amp. It sounded pretty good but not as good as the AC30 speaker. It sounded best using an EL34 power amp but still not as good as the AC30.
12/10/1997 12:55 PM
Jeff Lacio
i don't think this is anything new....i think Groove Tubes has had a similar amp like this in their line for several years.
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