Tube Amps / Music Electronics
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|11/6/1999 6:06 AM|
I have a hard time grasping which frequencies correspond to "cliche" guitar tones. Can someone help me out here with a synopsis of this, or point me to some further reading on this subject ?
Which frequency bands correspond to "sweet highs", "honky mids", "farty bass", "ice-pick highs", low-mids, upper mids, "tight bass", and so on.
Also, which frquency bands correspond to which open and fretted notes ?
I must somewhat sheepishly confess to a lack of comprehension of this. All info appreciated.
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|11/6/1999 6:25 AM|
|Psycho Bass Guy
low "E" on a guitar is 82.4 hz as you go up in octaves, the frequency doubles each time. This effect is cumaltive so, if you have a 2 octave neck on a guitar, the 24th fret "E" on the high "E"(1st)string is just a little above 2khz. However, you cannot limit the bandwidth of a guitar amp to this because the upper harmonic resonances define much of the way an amp sounds. The 82hz-2khz range is only the fundamental freqs of each note. Just like in acoustic instruments, the overtone series in an amp defines the timbre.
In answer to your question:
sweet highs are very cleanly defined freqs at harmonics with lower upper midrange content
honky mids are unattenuated central midrange to upper midrange ( a very bad problem in old bass amps)
farty bass is usually too much low frequency content with not enough power to push it. (ever boost the 100hz fader on a graphic EQ on a cheap radio?)
ice-pick highs are too much tone concentration at upper fundamentals with limited harmonic resonance
the scale for guitar goes like this:
low-200hz and below
lowermids-200hz to 1 khz
uppermids-1khz to 2.5 khz
highs-2.5 khz and above
different amps center their tone controls at different freqs
|11/6/1999 6:34 AM|
Very good questions, Fred, and there is no easy answer. Reagrding the frequency of each note, well, at concert pitch, "middle A" is at 440Hz, and there are 12 tones in western music, so if you do the math, the low E on the guitar is at juts above 80Hz, which means that high E is at 4 times that, so around 320Hz or so (grab a calculator and figure it out :/).
But the thing is that a guitar note is not a pure tone, and it is made up of lots of harmonics (as is any isntument, and the harmonic content is what gives the instument its timbre, so a piano sounds like a piano, a violin like a violin, etc.). Of course, the type of instrument (plucked string, wind, bowed, etc., will dictatet the harmonic content as well). That opens a can of worms and what sounds harsh probably cannot be attributed to a single frequency, or a range of requencies, but rather how they relate to the fundamental note being played.
Say, a MArshall JCM800 will sound ice-pick-like at low volumes, it will be very trebly and harsh. A Vox AC 30 with the "cut" wide open will be brighter, but sweeter... It's all in "the mix" and that all that's factual to me.
Typically, I prefer to get a lot of high end gain in an amp and then -- if needed -- roll off highs at the end of the signal chain, that makes it for a smooth sound with an "easy feeling" and pleasent break up. If you keep the highs under control throughout, you may find that the amp is "stiffer," and those are the only basic terms by which I go about voicing an amp.
I am sure K.G. and Randall Aiken can ellaborate much more in a technical way and perhaps point you to some pertinent literature. In as much as one can analyze a good sounding amp and determine its spectral characteristics, I (althoughI have some instrumentation) rely on my ears to get me in the ballpark, only using the scope when I encounter as onscillation for which I cannot trace the source without too much of a headache.
|11/7/1999 5:30 PM|
Fred let me preface this by saying that frequencies are frequencies are you shouldn't get used to thinking the frequencies themselves will equal a cliche guitar tone. A really good way to look at this is like a mixing board. You can cut or boost different frequencies with the EQ on a channel but it's the souce that makes or break the tone.
In my opinion I think that frequencies matter HOWEVER you can use three different types of caps with the exact same value and each one will sound different yeilding different tones results. I would experiment more with cap types as well as tubes etc. See how these things effect the tone of the amp.
I'm not sure I follow this question.
Have you built an amp yet? If not I would build something simple like a Fender champ and then start swapping out caps and tubes with different brands but make sure the values are the same. This will give you a better idea how different materials will effect the tone.
|11/7/1999 7:06 PM|
Yes, I have built an amp - an Allen Accomplice. I have also extensively tweaked a Twin Reverb and a Bandmaster, added post PI masters to both, and almost always have an open amp chassis on my workbench for playing around with (usually the Twin serves as a "testbed" for tweaks and mods).
I'm more of a mechanic than a theoretician, though, and make mods based on recommendations or experiments rather than really thorough knowledge.
I have never really gotten a good grasp on how frequencies correspond to basic tones, though, and am hoping to pick some brains here to remedy that !
|11/8/1999 12:11 PM|
- 250Hz fatness
- 1kHz "honky" mids
- 2kHz "presence" (boost it and you dominate the mix)
- 4kHz - boost it for that Brad Gillis trebly tone
- above 4Khz - "shimmer" (that "blackface" highs great for funky rythms)
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