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What would it take to objectively compare rig tone?

Discussion in 'Amps and Cabs [BG]' started by JimChjones, Oct 9, 2018.

  1. JimChjones


    Aug 6, 2017
    SE England
    I was just idly wondering about that. We use all these subjective phrases, about tone, but it ought to be possible to objectively compare one amp to another and see how they treat the signal differently...

    Do you folks in the design side of the industry do that yet?
    Obviously a frequency response chart is pretty easy and well established, but it seems to me there must be much more, especially if you dial in distortion.

    Would one input a pure tone or perhaps tone and harmonics, and with fourier analysis see how the balance and levels of harmonics changes when the signal goes through the amp? Would that give you a repeatable method for measuring the effects of distortion etc?

    Would changes to the signal envelope be significant? I suppose they must be if you consider compression of the signal...

    What other things might there be that affect the tone? I can see this getting very complicated to do rather easily. Is it more practical just to rely on the well attuned ear?
    EatS1stBassist likes this.
  2. lz4005


    Oct 22, 2013
    Since every individual's input to the amp is going to be vastly different based on how hard they play, type of pickups, instrument setup, active vs passive, knob settings, type of strings, picks vs fingers vs slap, etc, it's impossible to get the kind of objectivity you're after.
  3. I think in this instance, objectivity is subjective.
    MYLOWFREQ, MVE, Oddly and 10 others like this.
  4. Lobster11

    Lobster11 Supporting Member Supporting Member

    Apr 22, 2006
    Williamsburg, VA
    Well, that's just your subjective opinion, isn't it? :laugh:

    Even if you could objectively quantify every aspect of a rig's sound and hold constant all other factors (such as the bass, the player, etc.), nowhere in there would be the answer to the question, "What sounds good?"
  5. Wasnex


    Dec 25, 2011

    Frequency response and dispersion characteristics of the speaker are a huge factor IMHO. Also, once you get out in the real world, acoustics come into play and indirect sound becomes a significant factor.

    As far as why amps sound different, I think it largely comes down to frequency response and how gain stages and output sections overload.

    It's actually pretty incredible how much variation in sound you can get with a high quality parametric EQ and effects like compression and OD run in parallel signal chains to simulate overload conditions.

    Yep it can get complicated and lot's of people prefer to just to crank up their favorite all tube head. Running an all tube head is definitely more authentic. The advantage of the modeling approach I described above is your not limited to setting volume to a specific level necessary to get the desired level of drive from the output tubes. I would probably be more inclined to crank a tube head in a recording session, but for live work I want to be able to set volume to whatever level is needed so I can hear clearly without blowing out the venue.

    With an amp you could measure the output directly so acoustics and dispersion would not be a factor. However this does not account for interaction with speaker impedance.

    With a speaker system, acoustics are a huge factor in real life performance. Normally measurements are taken on axis. But dispersion and off axis characteristics have a huge impact on how a speaker sounds to the user. Many bass players set up their rigs in a way that intentionally prevents them from hearing the direct full range of sound the speakers produce unless they are standing >15' away. In many circumstances, the player is likely to hear so much indirect sound that it becomes hard to hear the instrument clearly.

    Consider a pair of 210s ground stacked, side-by-side versus a pair of 210s stacked vertically with the top cabinet tilted back a little to aim it at your ears. By simply stacking the speakers differently, you modify the dispersion and frequency response of the system in a noticeable way. Some people prefer it one way, some people the other.

    If you wan't an objective real world comparison you would have to measure the speakers in both configurations and the measurement would only be valid in a specific location in a specific hall. Moving the speakers would change the relationship of direct and indirect sound, so the measurements would no longer be valid. IMHO so YMMV
    Last edited: Oct 9, 2018
    Old Garage-Bander likes this.
  6. MattZilla


    Jun 26, 2013
    the pluckin fingas. the rest of the band.
    record a song or two with your band in your DAW with you going DI. Bring your DAW and a few mics to some guitar shops and re-amp your signal through a few rigs.
  7. I say it's high time we invoke the .... Carrot Factor. :)
    Wisebass, 2tonic, MattZilla and 2 others like this.
  8. Kro

    Kro Supporting Member

    May 7, 2003
    New Jersey
    I think a lot of what you're describing can be done with the right tools, at least as far as being able to somewhat see with your eyes things that you might be hearing with your ears. You already noted a few of the most basic tests:

    1. Run a calibrated flat frequency sweep and view any variance with the output
    2. Run a clean sine at various frequencies, and see which amp-introduced harmonics are generated
    3. Using a DAW, set up a stereo test environment with side one being the unaffected signal, and the other being an affected signal. Compare the wave-forms for signs of limiting/compression/noise/etc.

    I think those are the three primary ones that I've used personally when curiosity has gotten the better of me and I start wondering how certain gear works. I know that there are other tests that can be done with looking at scoped wave-forms and viewing clipping characteristics like squaring off, stickiness, etc., but that's an area where I still have even more to learn than the others.
    shughey likes this.
  9. One word: Anechoic Chamber.
    OK that's two words. I'll show myself out.
  10. Wasnex


    Dec 25, 2011
    True but most people don't gig in an anechoic chamber. In my experience test results are definitely useful, but they only tell part of the story. IMHO, it's best to try out your gear in the wild if you can. I.E. Use objective measures to narrow your choices, then make a subjective decision on which sounds best.
    HolmeBass likes this.
  11. True all dat!
    I think that an objective repeatable analysis of tone is out of reach for most of us, even with an anechoic chamber.
    And if the results can't be repeated, are they really all that objective.
    Besides it really won't tell you much about playing out in the wild, which is where the gear will be happiest.
    Like a monkey in a tree, if you're happy with your bananas then the rest really doesn't matter.
    Wasnex likes this.
  12. arbiterusa


    Sep 24, 2015
    San Diego, CA
    People who make amplifiers avoid distortion like the plague. Are you talking about distortion that the amp generates when driven beyond design limits (no reason to measure this as it is extremely undesirable to people who design this stuff) or distortion from an external source, like a pedal?

    I think your broader point is just something that the MI industry would want to avoid. Subjective opinion is what sells gear.
    mikewalker likes this.
  13. Kro

    Kro Supporting Member

    May 7, 2003
    New Jersey
    I really don't think that's true. They're just very specific about the types of distortion they want, and how it's elicited.
    Old Garage-Bander likes this.
  14. 2tonic


    Dec 22, 2015
    What would it take to objectively compare rig tone?

    An open mind. :rolleyes:
  15. Yup! They start with a clean sounding amp and then see what they can do to make it all nasty in the right way. ;)
    Wasnex likes this.
  16. 40Hz

    40Hz Supporting Member

    No two players are exactly the same. No two basses are exactly the same. No two sets of ears are the same.

    So while you may be able to get “deeply subjective” (there is such a thing btw) I don’t see where it’s possible to ever be objective, in the absolute sense, about a piece of music or music gear.
    Last edited: Oct 9, 2018
    tfer likes this.
  17. Good band name.
    Sers of Ears. :thumbsup:
  18. 40Hz

    40Hz Supporting Member


    Agreement on definitions…agreement on aesthetics…agreement on what’s significant and what’s not…agreement on assessment criteria…agreement on uniform method of assessment…agreement on criteria used for judgement calls…agreement on scope… :whistle:

    Shall I go on?
    2tonic likes this.
  19. 2tonic


    Dec 22, 2015
    Yes, please do!! :D
  20. MattZilla


    Jun 26, 2013
    2tonic likes this.

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