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Midrange,Overshoot, or Ringing Question?


 
8/10/2000 9:32 PM
K BULL
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Midrange,Overshoot, or Ringing Question?
I have read that when an amp gets that hollow howl sound. (Joe Satch, VAI,) it is actually a mid range notch in the square waveform or an overshoot.At the rising part of the wave is the ringing. At the top you'll get a dip from a deficiency at a certain mid range frequency. Does anyone know about this and how to get this sound without the lost in sustain ?  
K
 
8/11/2000 11:14 AM
Sweetfinger
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I dunno what you're even saying! I've always thought of the Satch sound as being fairly compressed, and sounds like its then pushed through a parametric mid-boost before going into a tube amp.  
 
Back in the day I used an Ibanez PQ-9 for a mid boost on all my lead sounds. I recall a magic moment when I sent the mid boosted signal into the front end of a Laney PT-50, ran the "out" of the Laney's FX loop into a graphic EQ set for a "scooped" sound, sent that into an old Boogie MKII, and then drove Laney's loop "in" with the "line out" of the Boogie. It made all small objects within 20 feet dance!
 
8/11/2000 12:37 PM
K Bull
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Thanks for the reply SF, I totally agree with you on the compression part and thats where the sustain comes in. I was thinking in the preamp where the signal gets clipped instead of it being a pure square wave or a rounded edge square it dips right after the leading edge or some call it a ring. However I think but I don't know that it only happens if the midrange is cranked to a certain band and then the suatain drops off which would explain the compression in the front-end. I sure would like to hear that sound you had. Looks nice,  
K
 
8/13/2000 11:53 AM
Sweetfinger
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In my experience, anytime you increase the midrange in any amp, you get more sustain. I don't think its possible for any guitar amp to produce even a "near" square wave. The waveform you are describing is pretty much what happens in all amps no matter what amount of midrange is going through them. I also don't see how losing sustain can cause compression. I'm still not sure what exactly you're referring to.
 
8/13/2000 3:43 PM
K Bull
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Thanks again SF, I was talking about physically adding compression to the front-end not the amp itself causing it. Anyway I found the text from a Dave Funk Book. Here goes: Whether the distortion is generated in the pre or power amp the desirable characteristics can be seen in the output waveform.. When a sine wave is clipped, it turns into a square wave. A square wave contains a high Hz component and a low Hz component. The vertical size of the square wave represent high Hz, while the flat tops of the wave represent low frequencies or dc for that matter. When you try to run a square wave through a circuit at levels exceeding its linear levels, the square wave gets further distorted by the circuits inability to track the waveform. At the rising front of the wave you'll get "overshoot" and "ringing" Across the top of the wave you'll get a non-flat response indicating a deficiency at some mid-frequency. The dip in mid-frequency response is called the Marshall notch. or the "hollow howl". You can generate the howl by turning down the midrange at the expense of losing your sustain.  
 
hmm (not with the amps on the market right now)  
 
Maybe all amps have this waveform I don't know but I want to get this sound without buying an old marshall or expensive amp.!,  
K
 
8/15/2000 3:58 AM
Bruce
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Re: Midrange,Overshoot, or Ringing Question??...Right ;>)
I've read that a few times too and it ALWAYS sounds like Funk gibberish to me!  
That statement always stops me as I've reread it over and over.  
Just because you read it in an amp book doesn't make it gospel.  
Also, keep in mind, nearly NO ONE really liked the way the clean or overdriven Thunderfunk amps sounded in an amp shoot out even though he'd have you believe something differently.  
I've never heard one myself and can't comment.  
 
I understand the idea of squared waves being filled with many harmonics above and below the fundemental but this statement reeks of typical  
Guru'ism or, "Oh oh...I have to think of something different to say now, but I'll keep it as nebulous as possible while trying desperatly to keep it important sounding in order to warrant my presence here". It usually isn't very important at all.  
 
I don't really understand what he is saying or doing by sending a sine wave through a preamp and getting these "square wave" signal coming out.  
A sine wave is a pure tone theoretically.  
Is he talking abut clipping it with diodes, diode acting tubes, massively overdriven class A preamp tube section... what?  
How many of you have followed a sine wave through the preamp with a scope and found these mysterious "Funked" clipped signals ladden with "hollowed out howl" or "overshoot and ringing" coming out the other end?  
Where is this "hollow howl" out thing?  
More gibberish to me.  
 
If it was a spectrum analyzer looking at the PI or the power tubes, I could picture some flat spots, dips and valleys with a multitude of different frequency signals passing at some extreme drive conditions. But not a basic preamp sine wave.  
I know there is no such thing as a pure sine wave when playing.  
 
It's a very hollow and meaningless comment to me.  
Someone explain what the heck he is talking about  
 
Bruce
 
8/15/2000 4:08 AM
Peter S
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Bruce,  
It's total BS as far as I can tell. Besides, sine waves are meaningless because guitars(or any musical instrument, do not produce sine waves). What the hell is the "Marshall Notch?" I've never heard ANYONE talk like this in 30 years of repairing designing and building amps.  
 
Peter S
 
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