Best Sounding Rig In The History of YOUR World?

Discussion in 'Amplifiers' started by LSchefman, Jan 24, 2016.

  1. Boogie

    Boogie SuperD

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    This actually worries me a bit. First, I'm secretly pining for an older 1960a/b cab with 25w Greenbacks...what happens if it doesn't work for our application? Would that push us to start mic'ing all instruments (that's a whole new bucket of worms)? Could this mean my hearing is more trashed than I think?
     
  2. LSchefman

    LSchefman Hears Tones

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    It doesn't really mean that. I played my old Two Rock through an old 1960 with greenies and it was AMAZING. And your amp is closer to that than most amps.
     
  3. DreamTheaterRules

    DreamTheaterRules Archon owning member

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    I wish there was software that would accurately stack and calculate frequency response curves. Is there such a thing? Would be interesting to see the V30/57 response curves, and would let you know real quickly why it cuts! (And yes, I realize that every tiny bit you move the mic changes the tone, just saying). V30 is up about 5dB from 2K-4K, and the 57 is up 3dB or more from 3K to 9K, and up over 5 dB from 4.5K to 7K .

    It always struck me funny that so many people who complain about the ice pick in the V30, throw a 57 on it which makes that ice pick at least twice as bad. Once V30 is broken in, it's not nearly as bad and can be fine with the right other gear for live, and certainly can be great for recording. And, sometimes what "cuts" live is "ice pick to the brain" when sitting in front of an amp at home.

    Edit: my micing comment above made me wonder something that has never occured to me before. When we read the frequecy plot on a speaker, exactly where was that response taken from? WE all know how the tone changes as you move from center to edge. I wonder at what point they take those plots? And, I'm relatively CERTAIN there is no standard spot to do so, which again emphasizes why you really need to TRY speakers to know what they sound like, you can't just look at the plots and know how they sound. (And that's just another reason you need to try them, as cone breakup, magnets, doping, etc. all come into play as well).
     
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  4. Dusty Chalk

    Dusty Chalk alberngruppenführer

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    You'd think so, wouldn't you? The frequency response of a driver at various different levels is easy enough; the impedance as well. The ability of an amp to drive a speaker with an impedance at a certain frequency is...doable, but now we're getting into the realm of, how does an amp or cabinet manufacturer release those number? It's not just a number, it's a graph. It's a graph of graphs, and that's just for the driver.

    And then, on the part of the amp manufacturer, if you choose to release those numbers, you now have a PR...I won't say problem, but conundrum. Because ultimately, you tune everything by ear, so releasing these numbers, you now have to defend them.

    I know I wouldn't.
     
  5. LSchefman

    LSchefman Hears Tones

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    Fixed it for ya. ;)

    Let's talk about a few things I feel pretty confident about, having recorded an awful lot of guitars and amps using various mics. The frequency curves published by speaker manufacturers haven't got much to do with real-world sound.

    First: The frequency curve of a speaker is measured in an anechoic chamber, and it's NOT measured in a speaker cabinet! As we all know, the cabinet's dimensions, its structure, how the speaker is mounted in the baffle (front or rear mount), whether the cab is open, closed or ported, right down to what grille cloth is used change the frequency response of the speaker - in other words, what you hear in a real speaker cabinet is nothing like the anechoic chamber response of the speaker, and certainly nothing like what's measured with a special frequency measurement microphone. Remember there's a lot of phasing that takes place inside a guitar cab - and out of phase signals cancel each other out. So dips can occur where you don't expect them merely looking at a response curve.

    Second: The impedance of the speaker changes with frequency. An 8 ohm speaker isn't 8 ohms throughout its range. It can be 1 or 2 ohms at some frequencies and 20 ohms at others. This affects how the amp delivers power to the speaker at various frequencies, and thus, the response curve.

    Third: Speaker distortion alters the frequency response heard in the room. The more distortion, the more the bass frequencies predominate. Add distortion from the amp or pedals, and you have a recipe for even more changes to the frequency you're hearing.

    Next, even looking at published response curves, there are lots of dips and peaks in the frequency response of both the speaker and the mic. Neither curve is all that consistent. Also, a guitar amp's high frequency response goes to maybe 5KHz, including the harmonic pitches. The fundamental notes on a guitar neck are listed here. As you can see, the high C on the 20th fret of a guitar is only about 1KHz; higher frequencies are generated only by harmonics:




    [​IMG]



    But most of the information a guitar amp is putting out is in the 100Hz -1KHz range. Here's the Vintage 30 speaker response plot, you'll note that the 500Hz - 1KHz range is fairly linear, and t's not too bad at 100 Hz, but it's starting its resonant peak at about 2 KHz. Remember that 2KHz is about double the frequency of the highest fundamental notes the guitar can produce:

    [​IMG]

    Here's the curve of an SM57. As you can see, its resonant peak starts gently rising between 3-4 KHz, but remember, the guitar amp isn't putting out much signal at 4KHz, and we know that none of that signal is a fundamental note, because that only reaches around 1KHz, max. In fact, most microphones have a presence peak that starts about 1KHz, and rises about 4-5 db, including classic mics like Neumanns, etc. The 57 isn't unusual in having a presence peak, what's unusual is that its presence peak starts at a higher frequency than many microphones!
    [​IMG]
    You've heard of a Pultec EQ - it's a legendary passive EQ that both boosts and cuts frequencies. But the EQ curves were slightly different. So you can cut bass and boost bass at the same time, for example, and the curve is merely re-shaped, it isn't like one cancels the other out. The way mics re-shape the frequency response can be very surprising, but in the case of the V30/57, instead of a bell curve, it combines to be a shelf boost.

    What the 57 (and other mics) do is impose their own areas of boost and cut on a speaker they're in front of. Sometimes the combination works, sometimes not.

    But here's what's crucial: most of the 57's high frequency boost is a higher frequency than the notes a typical guitar amp's producing. Same with the speaker itself, but their boosts start in different places. So there's boost in different areas of the frequency curves.

    The reason most mics have a presence boost is to make what's being recorded more intelligible in the mix. A 1KHz presence peak on a vocal mic, for example, means that the listener is more able to hear the words being sung clearly. Etc.

    Guitar amps put out a lot of 100-500 Hz information, because guitars put out mostly 100-500Hz information. If you look at the chart, only the high E string puts out any fundamental information over 500 Hz at the 12th fret! Well, guess where the mud accumulates in a mix?

    Muddy mixes get most muddy around 350 Hz, which is exactly centered in the range that most of us play guitar chords in. This is why a lot of engineers cut guitar EQ around 350 Hz. It reduces the mud, helps define the bass and kick drum, and they cut AGAIN at frequencies centered around 1KHz to help out the vocals.

    But you want to hear the guitar in a mix, right? So where do you want to boost? If you boost the very lowest frequencies, you screw with where the bass and kick drum live. If you boost at 1KHz, you leave no room for vocals' "presence peak." Remember, in fact, you've pulled the guitar back at the vocal frequency range.

    So engineers will boost the high frequencies. The wonderful API EQ is known for how friendly it is to guitar tones if you crank the high frequencies a lot!

    The beauty of the 57/V30 combination is that you don't have to use as much EQ to make the guitars sit in the mix well, you can cut a little 1KHz, and the highs wind up with a very nice shelf EQ from 2KHz on up, between the speaker and the mic's peaks. So the guitar tracks are intelligible, you can hear everything better, and you get the familiar tone we've all heard on ten zillion records.

    This is why recording engineers like the 57 - for the way the guitars naturally "sit" in the mix.

    This is also why the V30 and the SM57 work well together. Incidentally, most guitar speakers' curves aren't too dissimilar from the V30, we're talking degrees here, not quantum leaps. :)
     
    #145 LSchefman, Mar 1, 2016
    Last edited: Mar 1, 2016
  6. DreamTheaterRules

    DreamTheaterRules Archon owning member

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    yeah, I agree with pretty much everything you said. I was just pointing out that the peak in the two were pretty close and together added significantly to the response (which you pointed out) above the fundamental tones of the guitar. But yeah, when you start talking about these things you either A) write a book, and STILL leave pertinent info out, or B) oversimplify and leave TONS of things out.

    I know the second you drop those speakers in a cab, that frequency plot changes, and every cab you put it in changes it again. Same cab with no insulation vs. a little vs. a lot = three more changes in response. Depth of the cab even if same internal volume, changes it.

    In the audiophile world, everything is about every possible way to flatten frequency response, make the whole chain free from any distortion, viabration, coloration and do everything possible to maximize transparency of signal. In the guitar world, right from the start (and no matter how "clean" your clean tones are) we pick are pieces from guitar strings all the way through to speaker cones, based on the distortions or colorations that we prefer.

    I do have one question: You mentioned front vs. rear mounted speakers. I've ready multiple times where a guys said he preferred one over the other, but I've NEVER heard an explanation for why, or what the difference is supposed to be. Can anyone let me know what the differences are, and the logic behind them?
     
  7. LSchefman

    LSchefman Hears Tones

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    I think one big difference is edge diffraction. Higher frequencies tend to "travel" or radiate across the baffle of a loudspeaker. At the edge of the speaker baffle on a square cabinet, the edges add ripples to the frequency response of the speaker.

    Reducing this edge diffraction has been the thing many hi-fi and studio monitor speakers try to do with rounded or beveled edges around the front of the speaker cabinet. In any case, the baffle itself does matter to how a speaker sounds, and how the speaker's sound travels along the front of the speaker cabinet matters.

    Front mounted speakers are going to radiate along the baffle differently from rear mounted ones, one reason being the fact that a rear mounted speaker cone is deeper inside the cabinet, and in addition has the added thickness of the speaker baffle board's circular cutout itself between the cone and the baffle that also will affect the dispersion of sound waves.

    Some folks say that with a front mounted speaker, you hear more of the speaker, and it'll be a little brighter, and some say that with a rear mounted speaker, such as the usual Marshall and Mesa cabs, you hear more of the cabinet.

    My feeling is that these are both kind of exaggerations or old wive's tales, or at least, very big generalizations, because different designs for both front and rear mounted speakers are going to sound different anyway.

    I've had some incredibly bright rear mounted speaker cabs that you could literally hear fingernails on strings through, and some very dull sounding front mounted speaker cabs.

    So I guess the best answer is that it's one of many variables that come into play.
     
    #147 LSchefman, Mar 1, 2016
    Last edited: Mar 1, 2016
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  8. Boogie

    Boogie SuperD

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    All of my Mesa cabs are front mounted. Interesting!
     
  9. LSchefman

    LSchefman Hears Tones

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    Most of my Mesa cabs have been rear-mounted; that would include the Tremoverb combo, Blue Angel 2x10 Cab, Lone Star Combo, Maverick combo, Widebody 1x12 semi-closed back, and 2x12 Recto cabs. My only Mesas with front mounted speakers were a 4x10 Bass cab, and if memory serves, a Subway Rocket.

    I think they do different things with different models of their cabs and amps.
     
  10. DreamTheaterRules

    DreamTheaterRules Archon owning member

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    Thanks Les. I didn't think guitar speakers even put out high enough frequencies to have any edge diffraction, but it's been years since I studied that stuff.

    Even as much as I used to actually study it (I read The Absolute Sound, Stereophile, and more to this topic, Speaker Builder magazines for years!) I've never heard what the differences were supposed to be between front or rear mounted speakers in guitar cabs.
     
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  11. LSchefman

    LSchefman Hears Tones

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    All waves diffract, water, light, magnetic waves, etc. I don't think it's limited to very high frequencies.

    The point I was trying to make is that the baffle board is part of the sound propagation in a speaker system, via diffraction, and also its own resonant vibrations, flexing, etc,; and how the speaker is mounted seems to matter, but isn't the only factor. It may not even be a deciding factor.
     
  12. aristotle

    aristotle New Member

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    Well, sort of, but not exactly... Diffraction only occurs when the object or opening is on the order of, or smaller than, the wavelength. And for the purposes of this discussion, diffraction really is just a spreading out of the waves.

    In the case of sound from a loudspeaker, the loudspeaker shape itself is the primary "opening" that is associated with diffraction. Forgetting the cab for a moment, this is why a larger loudspeaker can keep bass frequencies more focused forward. 100Hz is about a 11.5' wavelength, which is way longer than the typical guitar speaker. So, the bass frequencies will spread out like crazy. Still though, a bigger speaker will cause less diffraction at the low frequencies and keep the sound more forward. 1.5KHz is about an 8.5" wavelength, which is shorter than the typical guitar speaker, so those components will spread out much less, and will be much more forward focused. That's why when you move off-axis from your guitar cab, you hear more bass and less treble.

    Compared to this, whatever physical geometry difference there might be relative to front vs. rear mounting is negligible. My strong guess is that whatever difference you hear between front and rear mounted cabs is due the other factors that you mentioned, and the fact that the speaker happens to be front or rear mounted in your examples isn't part of what you are hearing.
     
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  13. LSchefman

    LSchefman Hears Tones

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    That was my guess, that it's a small factor. But in similar cabs, I do hear differences. Not huge ones, but they're there.
     
  14. LSchefman

    LSchefman Hears Tones

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    One thing I'd note, however, is that in terms of fundamental frequency of notes on a guitar, as opposed to harmonic frequencies (certainly they are important, too), there are no 1.5 KHz notes (see the chart posted above).

    More typically, as the chart shows, up to about the 7th fret, most note fundamentals are under 400 Hz.

    Many are under 200 Hz. A 200 Hz wavelength is 1.75 meters (68.897 inches); A 300 Hz wavelength is 1.14 meters (about 45 inches); A 400 Hz wavelength is .85 meters (almost 33.5 inches).

    All of these wavelengths are present (if not predominant) in guitar playing through a loudspeaker, and all of these wavelengths are substantially larger than either the speaker cone, including its surround, or the opening of an amplifier to mount the speaker. In fact, I don't know of any cabs with 33.5 inch baffles, let alone speakers.

    So if the diffraction occurs where the opening is smaller than the wavelength, it's pretty clear that wavelengths at these frequencies are in fact larger than the opening, and I think most of us play a lot in these ranges on the neck.

    I'm no scientist, so if I'm wrong on this, please explain further. But it appears to me that diffraction plays a role in guitar speaker cabinets.
     
  15. Dusty Chalk

    Dusty Chalk alberngruppenführer

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    There's also edge diffraction -- audiophile speaker builders who avoid it (by, for example, making egg shaped speakers) go through great lengths explaining how boxy speakers sound "boxy" because of edge diffraction.

    [​IMG]
    So presumably if the actual sound source is recessed in a speaker cabinet, edge diffraction will come more complicatedly into play than the abovie diagram. I believe it's also a function of directionality, since the higher the frequency, the more directional it becomes (it's not simply a point source as appears in the diagram, off axis signal is attenuated compared to on axis signal, and the attenuation is a function of frequency).

    I am not a speaker designer, so my input to this is purely as a muggle, and could therefore be worth as much as you paid me for it.
     
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  16. DreamTheaterRules

    DreamTheaterRules Archon owning member

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    Back when I was into Speaker Builder magazine, I played with some Transmission Line loaded woofers. Weighing out cotton batting and carefully stuffing the line, adjusting line length to tune, etc. At that time, I figured some day I'd build a TL loaded guitar cab. It would be great in theory, but size prohibitive.
     
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  17. LSchefman

    LSchefman Hears Tones

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    Yes, in fact I mentioned this in my earlier post, though in a guitar speaker cabinet it's probably worse or at least different, because there's a raised lip around the edge of most guitar cabinets.

    It's one reason why most studio monitors have always had the grill cloth removed, not so much for the cloth itself as to eliminate the frame that holds the cloth in place.

    Today we're so used to seeing studio monitors without grille cloths and with rounded edges that it's hard to remember the days when I first got started, where the speakers used as near-field monitors were simply versions of hi-fi speakers with the grill cloths removed (Yamaha NS-10s were originally home hi-fi speakers for example, though by this time I was using B&W speakers that were also originally designed for hi-fi use, but were in a lot of British studios because George Martin used them), and lots of studios had giant Altec or Urei horn-loaded speakers made originally for use in theaters as mains, hanging from the ceiling via chains on the theory that this way the vibrations wouldn't be transferred to furniture or stands.

    And...egg crates....there were indeed studios with egg crates on the walls or ceiling.
     
    #157 LSchefman, Mar 7, 2016
    Last edited: Mar 7, 2016
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  18. rugerpc

    rugerpc A♥ hoards guitars ♥A
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    This is a great discussion. I have a pair of huge McIntosh speakers I inherited from an uncle who knew WAY more about audio than I did at the time. I've forgotten the model number, I'll look it up when I get home.

    I think about all this stuff every time someone makes a comment that they love or hate the tone of a guitar or amp they see/hear on youtube, and use that evaluation as the basis for purchase/don't purchase decision.

    It just makes me shake my head.
     
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  19. LSchefman

    LSchefman Hears Tones

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    I remember the McIntosh speakers...they were big bookshelf speakers with wooden slats in front, weren't they? Great sounding speakers for their time.

    EDIT - Are they like these? I found a pic.[​IMG]
     
  20. rugerpc

    rugerpc A♥ hoards guitars ♥A
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    No, not bookshelf models...

    Home for lunch. The speakers are a pair of XR 1052.

    XR1052 Loudspeaker System

    [​IMG]
    4-way floor system has 12" passive radiator, 10" woofer, 5" mid and 1" soft dome tweeter. Walnut finish. All black mounting rings for 5, 10" & 12". Woofer and passive radiator have vibration isolation mounting. Black grille cloth. Different cabinet construction for better appearance.

    Main and tweeter fuses are located at the back of the cabinet. Mid and tweeter level switches on early versions.

    Three position mid-range switch (450 to 1300Hz): 0dB, -1.5dB and -3.0dB
    Three position tweeter switch (1300Hz to 20,000Hz): 0dB, -1.5dB and -3.0dB

    Crossover frequencies: at 55Hz, 450Hz and 1.3kHz
    Impedance: 8 ohms
    Output: 82dB @1w/1m
    Power rating: 100w
    Size: 46-1/2"H, 16"W and 11-1/16"D
    Weight: 83 lb.
    Sold from: 1986-1991
    Last retail price: $1250.00 each


    Mine don't have the mid and tweeter level switches so they are not early versions.

    Pics when I get back to the office.
     

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