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About Matching Your Cabinet's Resonant Frequency

JMichael

New Member
@ barhrecords ... Interesting YouTube link regarding "tapping" the speaker to hear it's resonant frequency!

I found this link to an online audio freq generator ( Tinnitus Treatment Sound Therapy - Tone generator & Tuner | AudioNotch ), and I can listen to his tap on the YouTube video, then plug in the frequency noted into the online generator and I can get close.

It's a bit tough for me to hear the frequency when he taps the larger woofers., just sounds more like a "thud" to me. ;)
 

barhrecords

Axe-Master
@ barhrecords ... Interesting YouTube link regarding "tapping" the speaker to hear it's resonant frequency!

I found this link to an online audio freq generator ( Tinnitus Treatment Sound Therapy - Tone generator & Tuner | AudioNotch ), and I can listen to his tap on the YouTube video, then plug in the frequency noted into the online generator and I can get close.

It's a bit tough for me to hear the frequency when he taps the larger woofers., just sounds more like a "thud" to me. ;)
According to the book, he recorded the finger tap with a Zoom H2 digital recorder and then did an FFT in software to find the frequency.
 

Rex

Legend!
It's a bit tough for me to hear the frequency when he taps the larger woofers., just sounds more like a "thud" to me. ;)
That's the problem with the low-bass frequencies: they tend to sound like thud. That's also why (sorry for the soapbox hijack) too much bottom end can destroy a guitar tone in a mix.

Also, note that he was using test equipment—not his ears—to measure the resonant frequency when he tapped the cone.
 

bansta

New Member
I'm trying to find the LF resonance of the combination Friedmann HBE + Cali Lead 80s Mix using the filter block between the amplifier and the cab. I hear the most pronounced resonance at 165-167Hz, but this is definitely not the cab resonance? Could somebody tell me how does the "real" cab resonance sound and what is the proper frequency for this cab (Cali Lead 80s Mix) please?
 
sorry guys, I'm lost... I currently use a matrix with two 1x12 Bogner Cubes (closed back) with Vintage 30's. Where can I find the info on how to set the LF resonance? Is this the only parameter I have to change? Do I change it the same in every amp sim? Again, sorry if this is a dumb question... any advice appreciated.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
I'm trying to find the LF resonance of the combination Friedmann HBE + Cali Lead 80s Mix using the filter block between the amplifier and the cab. I hear the most pronounced resonance at 165-167Hz, but this is definitely not the cab resonance? Could somebody tell me how does the "real" cab resonance sound and what is the proper frequency for this cab (Cali Lead 80s Mix) please?
The first line of my OP states:

"This post is aimed at those who use a solid-state power amp into a [size=+10]conventional guitar cab."[/size]
 

fredster

Inspired
Never mind - found my own answer. Impedance at resonance has to be obtained from the manufacturer.
 
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Moltenmetalburn

Self-Admitted Software Thief
I don't think that will do the trick. Sag is calculated in the power amp simulation; if you turn that off—no sag.


Cliff told me this would still work as the preamp sag is tied to the power amp. He said if I set the sag value to zero it will disable the preamp sag but the global power amp off only disables the power amp sag.
 

Rex

Legend!
Cliff told me this would still work as the preamp sag is tied to the power amp. He said if I set the sag value to zero it will disable the preamp sag but the global power amp off only disables the power amp sag.
I didn't know that.

If that's the case, it begs the question: When you turn off the power amp sim globally, does that disable any other features of the power amp sim, or just the sag? Is the power amp software still running—changing the sound in other non-sag-related ways?
 
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joegold

Fractal Fanatic
The first line of my OP states:

"This post is aimed at those who use a solid-state power amp into a [SIZE=+10]conventional guitar cab."[/SIZE]
I really have no desire to irritate you Cliff, but with an FRFR system - Is it not a good idea to know the low res freq of the drivers and plus the cabinet used in the IR when dialing in the Amp Block?
 

Rex

Legend!
Switching off global power amp modeling affects more than sag. For ex the Presence control.
That's what I thought. Leaves me confused about how preamp sag would continue working; it's based on power amp sag.
 

barhrecords

Axe-Master
I really have no desire to irritate you Cliff, but with an FRFR system - Is it not a good idea to know the low res freq of the drivers and plus the cabinet used in the IR when dialing in the Amp Block?
I think that is legit; matching the AMP block SPKR page settings to an IR and using FRFR.

It's just that this thread is not about that. This thread is about using conventional guitar cabs.
 

joegold

Fractal Fanatic
OK.
Fair enough.
But threads on internet discussion forums tend to go where they go.
I've never really thought of that as a bad thing myself.
Trying to force a discussion to always stay 100% on topic seems sort of futile to me.
 

Moltenmetalburn

Self-Admitted Software Thief
That's what I thought. Leaves me confused about how preamp sag would continue working; it's based on power amp sag.


It's not based on, it's tied to the preamp sag parameter. Totally different .

The knob controls both functions, preamp and power amp sag simultaneously.

They are still separate.

The global power amp off allows you to turn off only the power amp modeling. This leaves preamp sag working and controlled with the sag knob.

If you switch the sag parameter to off, (PA OFF) then all sag modeling is defeated both pre and post.
 

fredster

Inspired
Ok, just tried this. I'm running a Carvin 1540L into a Mesa 3/4 back with a V30.

V30 specs:
Resonance frequency, 75Hz
DC resistance 7.3ohms
Celestion tells me at resonance the impedance is around 100ohm

Following Cliff's formula, I get 20*log10(100/7.3) = 22.73. Divided by 2.4 = 9.47
Soooo, Lo Res Freq at 75 and Lo Res value of 9.47.

Result: Pretty damn good! Playing around with the Rectos got me a very convincing RectoVerb (which that cab was designed for). At least how I remember, it's been a while since I had one. This really helps answer questions like "What would an AC30 sound like through this cab?"

Thanks Cliff, this was very helpful!
 
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