• We would like to remind our members that this is a privately owned, run and supported forum. You are here at the invitation and discretion of the owners. As such, rules and standards of conduct will be applied that help keep this forum functioning as the owners desire. These include, but are not limited to, removing content and even access to the forum.

    Please give yourself a refresher on the forum rules you agreed to follow when you signed up.

About Matching Your Cabinet's Resonant Frequency

Semih Yanyali

Power User
Well i think even he wasnt sure :)....i remember setting it to 85hz @ LA Amp show...thats the way i use it since than...sounds and feels better to me with the amp sims i use (ac30, vibroverb...)

Sent from my SGH-T989 using Tapatalk
 

joegold

Fractal Fanatic
EV 12L spec sheet:

Thiele-Small Driver Parameters
fs (free-air resonance frequency): 55 Hz
Qes (electromagnetic Q at fs): 0.245
Qms (mechanical Q at fs): 4.37
Qts (total Q at fs: (Qes Qms) / (Qes + Qms): 0.232

I had a cab with 2 EV 12Ls. I measured the LFR by ear using the old trick*, resulting in 72Hz IIRC.

* "One way to find the SRF is to put a Filter block after the amp block. Set the type to Peaking, Q to 5 or so and Gain to 10 dB. Start with a Freq. of 50 Hz. Play some chugga-chugga and slowly adjust the Freq. until you hear and feel the cabinet resonate. Make a note of the frequency. Remove the filter block and set the amp block SRF to match."
Was that an open back cab?

As I said, I did the same method (the filter-chugga-chugga method) with my 12L-loaded open back cabs and got 69.3hz.
So we're pretty close to each other.

According to Cliff's quick-and-dirty-formula method for a sealed cab it would be 60.5hz.
(55 hz + 10% = 60.5 hz)

I wonder what the audible effect of such a low lo-res-freq really is though since the lowest E on a guitar is around 82.4hz (in equal temperament @ A=440).

And the filter-chugga-chugga method might just be bringing out the freq of the notes you're actually playing on the guitar rather than the speaker's resonant frequency.

Also, the IRs I tend to use now now for FRFR are of 12L-loaded Thiele cabs which are closed back and ported.
I'm wondering now if it would be better to use a slightly lower lo-res-freq when I'm going FRFR as opposed to through my cabs.
E.g. 69.3 hz for the real open back cabs and 60.5 hz (according to Cliff's formula) for the IRs.
I'm obviously just splitting hairs here and it won't make any audible difference, but I'm kind of anal that way.

PS
I love the idea of a Global Low Resonant Frequency that can be applied to all amp sims.
 

barhrecords

Axe-Master
With an FRFR system you want the resonant frequency of the speakers used in the IR you're using, not the resonant frequency of the FRFR cab.
I've always gone with the "what sounds good is good" for the speaker page in regards to IR's and FRFR.

I do wonder if getting the speaker page params close to the speaker used in the IR changes the "feel" of playing the preset?

Because the sound of the AxeFx II is so stellar, I find I'm chasing the "feel" more than the sonics these days. The audio quality is so righteous already.
 

smcrosby

Power User
Just curious - so this thread would apply to someone who ran their AXE FX II into a solid state Roland JC-120 combo amp with a built-in open back cab? :)
 

Stadanko

Inspired
Another thought here. What consideration should be given to having multiple speaker types in a single cab. Split the difference? i.e one speaker is 85Hz and another is 90Hz, then consider 87.5Hz?
 

guitardoc

Experienced
A great write up as usual Cliff! One thought that cropped up and that might help Poweramp/Cab guys is the idea of a global Low Freq Resonance Setting. This would allow you to override the setting for all amps depending on what guitar cab you are using at the time. This would be useful if heading out to a fly show or a rehearsal space where you probably wouldn't take your own cabs. Otherwise you may have to tweak quite a number of patches which could be time consuming. As usual just a thought. Cheers Spence
It would be extremely convenient to have two different global low frequency resonant settings - one for output 1 going with cab sim to FOH and one for output 2 going without cab sim to solid state amp + conventional guitar cab. Don't know if this is feasible though...
 

PacoCasanovas

Fractal Fanatic
It should be possible to extract at least the LF resonance frequency value out from an IR file! Almost every IR uses a simple "sine sweep" as reference signal, so it's possible to measure the phasing between the reference- and the response signal. There is a major phase change caused by the speaker resonance frequency. Maybe this could be a nice plus for a further data synchronisation between the cabinet- and the ampblock ;)
 

barhrecords

Axe-Master
It should be possible to extract at least the LF resonance frequency value out from an IR file! Almost every IR uses a simple "sine sweep" as reference signal, so it's possible to measure the phasing between the reference- and the response signal. There is a major phase change caused by the speaker resonance frequency. Maybe this could be a nice plus for a further data synchronisation between the cabinet- and the ampblock ;)
You would have to have the exact test signal though correct? Not just an assumption and a generic sweep?
 

PacoCasanovas

Fractal Fanatic
You would have to have the exact test signal though correct? Not just an assumption and a generic sweep?
The testsignal would be easy, if it's the same which is used by the IR capturing in the AxeFx. But since a de-convolved signal contains no phase shift information , I'm afraid to tell this wont work....*sometimes my brain play tricks on me....ouch!:nightmare:* - I stand corrected! :()
 

mtmartin71

Experienced
I'm not understanding this then compared to what defaults in the amps under the speaker page. For example, the Marshall plexi defaults at a LF of 114 Hz. Typical speaker cab attached to that would be a Marshall 4x12. G12M greenbacks are a very common speaker in those. Looking at the OH Marshall IRs, there are the M55 PRs with 55 representing (I believe) the LF. There are also M RI 75s where 75 represents (I believe) the LF. So if you assume the 10% cab enclosure method then you're talking about values of 61 and 83 respectively...way lower than the defaults. I've also read elsewhere that people have measured their Marshall cabs up around the 110-120 levels. Jay Mitchell states that's the average for a 4x12. Cliff noted in his post that trying to dial by feel (which I interpret as ear) is not a good way yet Scott P states that's the best way to find the right frequency. Color me confused...I'm just sticking with the stock values and if anything, adjusting down the LF if it's too boomy for my tastes. Just trying to educate myself...
 

Ka_Status

Member
Hi friends. So when I connect my Axe into the Valve Poweramp of my Head shuold I set resonance values in amp block to 0?
 

PacoCasanovas

Fractal Fanatic
I'm not understanding this then compared to what defaults in the amps under the speaker page. For example, the Marshall plexi defaults at a LF of 114 Hz. Typical speaker cab attached to that would be a Marshall 4x12. G12M greenbacks are a very common speaker in those. Looking at the OH Marshall IRs, there are the M55 PRs with 55 representing (I believe) the LF. There are also M RI 75s where 75 represents (I believe) the LF. So if you assume the 10% cab enclosure method then you're talking about values of 61 and 83 respectively...way lower than the defaults. I've also read elsewhere that people have measured their Marshall cabs up around the 110-120 levels. Jay Mitchell states that's the average for a 4x12. Cliff noted in his post that trying to dial by feel (which I interpret as ear) is not a good way yet Scott P states that's the best way to find the right frequency. Color me confused...I'm just sticking with the stock values and if anything, adjusting down the LF if it's too boomy for my tastes. Just trying to educate myself...
I can tell you, it's a difference if the cabinet is closed or open back. Most resonance peaks on cabinets were between 80 - 110Hz, depends on the speaker size, speaker wiring (series, parallel) , size (TSP!!), open or closed back (or mixed! -> Cliff's favorite is a Mesa 4x12 cab from the late 80s, these cabinets were half open, half closed) or ported housing.......

Before you start turning on the advanced parameters, just make a new preset with a all fresh all new amp block and your prefered IR in a fresh new cabinet block (best is to choose a MIX-IR from the stock cabinets, you won't to choose a specific microphone and there is not much distraction from the proximity parameter, which also can pump up your LF feel)! Remember, the IR is one of the most important parts of your tone when working with a FRFR setup. After that, leave your Amp EQ at the default settings. If you want to learn how LF and HF resoance work, turn up the Master Volume on your patch, because this is most hearable with higher MV values. Note - don't push it too hard then, not too high pre amp gain values - otherwise your sound might get too flubby, it's just a "howto" for learning/understanding how these parameters will work, so you can make a slight (but right) change on your desired presets!

Have fun!
 

mtmartin71

Experienced
I can tell you, it's a difference if the cabinet is closed or open back. Most resonance peaks on cabinets were between 80 - 110Hz, depends on the speaker size, speaker wiring (series, parallel) , size (TSP!!), open or closed back (or mixed! -> Cliff's favorite is a Mesa 4x12 cab from the late 80s, these cabinets were half open, half closed) or ported housing.......

Before you start turning on the advanced parameters, just make a new preset with a all fresh all new amp block and your prefered IR in a fresh new cabinet block (best is to choose a MIX-IR from the stock cabinets, you won't to choose a specific microphone and there is not much distraction from the proximity parameter, which also can pump up your LF feel)! Remember, the IR is one of the most important parts of your tone when working with a FRFR setup. After that, leave your Amp EQ at the default settings. If you want to learn how LF and HF resoance work, turn up the Master Volume on your patch, because this is most hearable with higher MV values. Note - don't push it too hard then, not too high pre amp gain values - otherwise your sound might get too flubby, it's just a "howto" for learning/understanding how these parameters will work, so you can make a slight (but right) change on your desired presets!

Have fun!
Thanks for this info. I'm actually pretty versed on playing with some of these things but was just confused on some of the different pieces of information around it. I'm also mostly using the OH Marshall mixes at this point because I find most of the stock mix IRs to be a tad too dark for my tastes. I do love the TV 4x12 though.

I think what would be cool is to add to the Wiki is a list of cabs with measurements taken. That way if you're using an IR or the real deal, you can reference that as the starting point. Another option, at least for the IR crowd, is start making the IRs with the data built in at the time of creation such that the amp block can "read" the cab block which would be built and contain those measurements. Even if you can't capture it per se when making the IR, if the IR format had a "tag" feature like a MP3, the author of the IR could have the option to put in the measurements of the IR. This way when you pair a cab with the amp, the amp block can read the tag and automatically assign the values for that virtual cab right into the speaker page. This would be better than a Wiki list and a time saver in my eyes. Maybe that's an Axe FX III thing :)

At the end of the day, I typically pair the recommended cabs with the default Speaker page settings so it's really not too big a deal. Preference wise, I tend to not like overpowering bass. I leave that range for the bassist. If I'm getting that, I might turn down the LF value or I'll just turn down the bass control itself...maybe even use the cut switch to tighten it up.
 
Top Bottom