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Speaker Page - Does any of this make sense?

Discussion in 'Axe-Fx II Discussion' started by joegold, Feb 8, 2016.

  1. joegold

    joegold
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    I usually use a Matrix GT1000 into one or two 1 X 12" open back cabs loaded with EVM-12Ls.

    Long ago Jay Mitchell suggested that the LF for this driver in a cab like that was probably around 65hz, so I would always set this on the Speaker Page, no matter which Amp Type I was using, and it did seem to help a bit although any differences from the default LF for whatever Amp Type I was using was very very subtle.

    I would always leave the LF Q and Resonance level alone though because I simply don't understand anything about how to set them.
    Ditto for all the HF parameters.

    At some point I tried the chugging away on the low E string method to determine the *actual* LF of one of my actual cabs and thought I heard a resonance at 69.3 hz, so I set all my LF values to that in all my Presets for a while, but it was just voodoo to me.

    But today I think I came up with a more logical way to find the LF.
    I put a Synth Block set to a sine wave with Track set to off, to get a tone generator, along with and an Amp Block with the Tube Pre selected as Amp Type (all tone knobs at 12:00) and started to sweep the freq of the sine wave in 1hz increments.
    And I thought I noticed at distinct jump in volume, i.e. a resonance, at 62hz.

    So I went and changed all my LF settings in all my Presets to 62hz and it does seem to tighten things up.

    I basically use 3 amp types in all my Presets at the moment: Double Verb Vib, Deluxe Verb Vib and MKII C+ Deep.
    All of these Amp Types have quite different values for all of the parameters on the Speaker Page.
    And all I'm really doing right now is changing the LF to 62hz.

    But when you look at the stock values for the Deluxe's Spkr Page it looks to me like Cliff may have based those values on a Deluxe with an EVM-12L in its open back cab.
    E.g. The stock LF for this Amp Type is 65hz.
    But, probably the most common driver in BF Deluxes was the Jensen C12Q, no?
    The C12Q's published free-air LF is 87.3hz, so mounted in an open back cab it would be over 100hz.
    So, the stock values for this Amp Type are definitely not based on the C12Q.

    Based on that notion I decided to try copying *all* the stock Speaker Page values (including Q. Resonance, HF slope, etc.) for the Deluxe sim into *all* my other Presets' Amp Types, except that I use 62hz instead of 65hz for LF.
    And this does seem to tighten things up.

    Does that make any sense to do at all?

    I have no advanced math chops, so when I see Cliff's suggested equations, with log10 etc., for calculating this stuff, my eyes just glaze over.
    But if the stock values for the Speaker Page of the Deluxe sim really are based on a 12L in a Deluxe cabinet I think i may be on to something.

    Y/N?
     
  2. Keg8605

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    On a side note - I'd love a way to make that speaker page copy and paste or global or something separate somehow for us power amp/cab people.
     
    MNG likes this.
  3. joegold

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    Bump.
     
  4. FractalAudio

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    The values for the Deluxe Reverb model are based on measurements of an actual 65 Deluxe Reverb, not some hypothetical values on some spec sheet.
     
  5. joegold

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    OK. Thanks.
    Any ideas as to why the LF Res is so low on that cab when the typical driver used in those amps usually has a free-air LF Res that's much higher?
    I thought that the LF Res value for free-air usually goes up rather than down when the driver is mounted in a cab. Y/N?
     
  6. FractalAudio

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    You're assuming the specs in 2016 are the same as in 1965?
     
  7. joegold

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    I must be making some false assumption(s) somewhere but I'm not sure what it is.

    I thought that the Jensen C12Q or something similar to it would have been the driver used in a stock 65 Deluxe Reverb, no?
    At any rate, I guess that's irrelevant, either way, here.

    So, if you don't mind, what is the actual driver used in the actual amp you used to make this model from?

    And...
    Did you happen to make *any* of the amp models in the Axe with the real amp's speaker-out connected to an EVM-12L loaded open back cab while you were taking the test data?
    And if there is an amp model like that inside the Axe at the moment, would it make any sense at all for me to copy the Speaker Page defaults for LF and HF from that amp sim into my own Presets' Amp Block?

    Yes, I'm obviously overthinking the Speaker Page parameters at this point.
    But every time I make an adjustment to these parameters I really feel like I have no clue what I'm doing.
    The obvious solution is to just leave them alone.
    But setting the LF to 62hz, with my cabs, does seem to improve the tone somewhat so I'm wondering if there's anything else I could or should be doing with these parameters.

    The idea is to make the amp sim's response and output behave as if it was a real amp connected to a cab very much like my own cabs, as much as that is possible to do.
    E.g. A real Mesa MKIV will not only sound quite different with regards to frequency response if it's connected to a closed back 4 X 12 with V30s in it as opposed to a 1 X 12 open back cab with an EVM-12L in it but will also respond differently as far as many other characteristics beyond mere frequency response.
    No?.
     
  8. FractalAudio

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    If you want to be anal about it then buy yourself an impedance tester and measure your speaker. Use the formulas I've given on here before and calculate the values.

    And, no, a real MKIV will NOT sound quite different wrt frequency response due to the frequency flattening aspects of negative feedback.
     
  9. joegold

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    Always thankful for your input Cliff.

    Thanks.
     

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