Spkr Res Freq - Intelligent use of?

[guitarnerdswe]

It looks to me like Cliff has already set the SRFs in the Amp Block to default values that are slightly higher than the published resonant frequencies of the speakers used in the original amps.

In my case, since I'm using an EVM-12L, it might make sense to alter the default SRF values because none of the amp sims appear to have been made with an amp driving an EVM0-12L in mind.

I can't see the reason for altering the default SRF values unl;ess you're using a cab sim that is drastically different from the type of speaker used in the original amp, or unless you're in a situation like mine where you're monitoring the Axe through a guitar speaker with a known resonant frequency.
And even then it's questionable whether or not altering the value(s) makes any sense.
For example
Do I want the Deluxe Verb sim to interact dynamically with its virtual speaker as if that virtual speaker was an EVM-12L?
Maybe yes and maybe no.
It might sound more musical for the programmed virtual speaker interaction to remain as authentic as Cliff programmed it to be and for me to just let my power amp and speaker do their own thing.

Again, it's a parameter whose effects are pretty subtle, unless you're using lots of simulated power amp distortion.

I noticed that certain amps, the should use the exact same cab/speaker (like the Recto new and the other Rectos), have different SRF.

 

[VegaBaby]

It looks to me like Cliff has already set the SRFs in the Amp Block to default values that are slightly higher than the published resonant frequencies of the speakers used in the original amps.

In my case, since I'm using an EVM-12L, it might make sense to alter the default SRF values because none of the amp sims appear to have been made with an amp driving an EVM0-12L in mind.

I can't see the reason for altering the default SRF values unl;ess you're using a cab sim that is drastically different from the type of speaker used in the original amp, or unless you're in a situation like mine where you're monitoring the Axe through a guitar speaker with a known resonant frequency.
And even then it's questionable whether or not altering the value(s) makes any sense.
For example
Do I want the Deluxe Verb sim to interact dynamically with its virtual speaker as if that virtual speaker was an EVM-12L?
Maybe yes and maybe no.
It might sound more musical for the programmed virtual speaker interaction to remain as authentic as Cliff programmed it to be and for me to just let my power amp and speaker do their own thing.

Again, it's a parameter whose effects are pretty subtle, unless you're using lots of simulated power amp distortion.

That makes sense if you're using the cab IR that was 'intended' to be used with a specific amp. On purpose I tried to use 'mismatched' combinations and there I got quite good results by altering the amps SRF to the speaker.

When using a Deluxe like in your example I'd most definitely use a Deluxe cab as well, so probably no changes needed, still an amp like the Twin is used widely with JBLs and Jensens and they have very different SRFs, where it may make sense again to adjust...

 

[chase]

Given the difficulty of determining the "correct" value, it seems to me that the best approach (aside from ignoring it) is to simply tune it by ear and go with whatever sounds best - if that's not the same as the authentic cab, then you've just improved on reality.

 

[electronpirate]

Been awhile on this one, and since it's come up in recent threads (and that I had *somewhat* promised to look some of this up, thought I'd post a few that I just looked for.

Caveats:
-If you read through this thread, you'll see that there are a number of factors involved here, so you may see very little effect, or quite a bit. Jay's responses here are valuable, but it's good to see where those answers came from.
-This information is off the INTERNET. While I tried to stick with reputable sites (i.e original manufacturers,) I cannot verify the complete veracity of what I've found.
-USE YOUR EARS. If you read through this thread, you'll see that while we have a number to play with, tonally the suggestion is to dial it higher on the amp (i.e. SRF listed for the speaker is 75Hz, but 85Hz *may* sound better.

Didn't do them all, just the 1st few I thought most folks use. If it's this dead at work next week, I'll work on others, or chime in with yours. Once compiled and VERIFIED, we can WIKI this stuff.

Format:
Stock Cab Type
Which Speaker
FRes.

Enjoy:

Tweed 1x12:
Jensen P12Q?
Resonance Frequency 90.4 Hz

1x12 Black
Jensen P12N?
Resonance Frequency 90 Hz

1x12 Brit
Celestion Alnico Blue
Resonance Frequency 75Hz

1x12 E12L
EVM-12L
Resonance Frequency 55Hz

1x12 Studio
Mesa 22 Caliber
CANNOT LOCATE.

2x12 Black
Jensen P12N?
Resonance Frequency 90Hz

2x12 Brit
Celestion Alnico Blue
Resonance Frequency 75Hz

2x12 Blue
Chicago Jensen P12Q
Resonance Frequency 90Hz

2x12 G12H
Celestion G12H 2x12 (far-field IR)
Resonance Frequency 55Hz

4x12 Brit
Celestion Vintage 30
Resonance Frequency 75Hz

4x12 20W
20 Watt Greenbacks
Resonance Frequency 86.9Hz

4x12 25W
25 Watt Greenbacks
Resonance Frequency 75Hz

4x12 30W
Celestion G12H
Resonance Frequency 55Hz

 

[G-Man Music]

Thank you for posting these and like your idea of compiling these for a Wiki tid-bit.
After reading Cliff's post on this subject yesterday and seeing how this forgotten parameter can help "beef" up the tone in a good way, I'll have to spend some time with it. Like you said, it still comes down to what sounds best to you and not so much as to sticking to a set factory number that may or may not be the correct freq. for that cab/speaker.

It would be cool if the IR companies like Redwire or OwnHammer supplied the freq.# for each of their cabs if that is they had that information.

 

[FractalAudio]

A cool way to use this is to just pick a palm muted low E while turning the "knob". Try to hear where the most natural bottom is. Just like tuning a drum. Eventually you'll hear the natural pitch of the drum. I find this parameter to do something of the same with the bottom frequencies.

Nerdy, but cool

That's similar to what I do. I play a muted low E using my thumb "slap-bass" style. Set to the neck pickup, lower the Damping to exaggerate the effect and then tune the SRF until I hear the cab "sympathize". The put the Damping back to the default value.

Note I only do this when playing through a real guitar cab. If going direct or FRFR I don't bother.

 

[mortega76]

How does "locating the Spkr Res Freq" work for a cab that is running different types of speakers... for example in my case I run two Marshall cabs with G12T-75's (85hz) and V30's (75hz) in X-pattern? Would the "ideal" Spkr Res Freq be 80hz?

Also, I see some of you are running standard tuning... how would this apply to alternate (Dropped Bb) tunings?

Thanks!

 

[Jay Mitchell]

How does "locating the Spkr Res Freq" work for a cab that is running different types of speakers...

It will be different.

for example in my case I run two Marshall cabs with G12T-75's (85hz) and V30's (75hz) in X-pattern? Would the "ideal" Spkr Res Freq be 80hz?

No. The numbers you cited are for the speakers in free air, not in an enclosure. This is explained in my earlier posts in this thread.

how would this apply to alternate (Dropped Bb) tunings?

It has nothing to do with guitar tuning. Additionally, the term "resonance" implies something that does not happen. A cab being powered by an amplifier - any amplifier - does not "resonate" at its "resonant frequency" the way, for example, the resonators in a set of vibes do.

Here's a quick demonstration anyone can do. With your cab not connected to anything, tap on the cone of a speaker and observe (watch and listen to) its motion. Now, connect it to the amp and do the same thing. There will be a huge difference. The amplifier's output stage does an excellent job of damping the "resonance." The only audible effect of "resonant frequency" with a physical amplifier is a small response peak (~3dB max) at that frequency. Amps with no negative feedback and/or undersized output transformers are affected most (up to 3dB), while amps with negative feedback and/or robust OTs are affected by amounts that are small enough to be completely inaudible (.1dB or less).

 

[yek]

Ron, fine initiative. Good addition to the Wiki.

 

[Stratoblaster]

I've attempted more than once in the past to get this point across, but I gave up some time ago. Even within the Axe-Fx - i.e., using cab sims - in order to get an approximation of the interaction between tube amp and speaker, you've got to set the resonant frequency to a value that's in the ballpark (+/- 10% is more than close enough) of that of the original speaker. If you don't know what that value is, a little investigation is in order. There's no way to reasonably automate this in the Axe-Fx, because speaker and cab sim would have to exchange data in addition to realtime signal values.

Jay's post inspired my curiosity so I measured the LF resonant peak of my circa 1982 Marshall 4x12 260 Watt cabinet with G12-65 speakers. Some people were interested in the LF peak on another thread, so I thought I'd measure my cab and post it.

The resonant peak of my cab is 115Hz.

 

[OmegaZero]

I sent Red Wire an email with Cliff & Jay's descriptions of what we're looking for (taken from the previous thread), and asked if they could measure this for their modeled cabs. Mike seemed to think we could get this information from the impedance curve graphs they provide along with each IR. He provided this example:

Ran some white noise through the curves and made this pretty picture:

Jay et al. - Please forgive me if I'm not understanding this correctly, but would the peaks shown on these graphs be accurate values to set for SRF?


On a different note, I sent a similar email to OwnHammer. Kevin replied that he would be happy to try measuring this for their modeled cabs if someone would send them a description of how best to do it.

 

[Jay Mitchell]

would the peaks shown on these graphs be accurate values to set for SRF?

No. The graphs you have are obviously free-air impedance plots. Had the same data been taken on actual cabs, you could use it to identify the "appropriate" choice of speaker resonant frequency. The frequencies at which the peaks occur in your data are all too low.

Here's a way to make this simple: set speaker resonant frequency somewhere between 100 and 120 Hz, and fuhgeddaboutit. That figure is within 10% of the resonant frequency every guitar cab I've measured, and anyway it will only have an audible effect if you're using an amp sim with little or no negative feedback (e.g., Class A or Mr Z).

 

[Mike Snider]

Here's a way to make this simple: set speaker resonant frequency somewhere between 100 and 120 Hz, and fuhgeddaboutit. That figure is within 10% of the resonant frequency every guitar cab I've measured, and anyway it will only have an audible effect if you're using an amp sim with little or no negative feedback (e.g., Class A or Mr Z).

Given your extensive knowledge on loudspeakers, i'd say this is solid advice.
Thanks Jay.

 

[knoll]

would the peaks shown on these graphs be accurate values to set for SRF?

No. The graphs you have are obviously free-air impedance plots. Had the same data been taken on actual cabs, you could use it to identify the "appropriate" choice of speaker resonant frequency. The frequencies at which the peaks occur in your data are all too low.

Here's a way to make this simple: set speaker resonant frequency somewhere between 100 and 120 Hz, and fuhgeddaboutit. That figure is within 10% of the resonant frequency every guitar cab I've measured, and anyway it will only have an audible effect if you're using an amp sim with little or no negative feedback (e.g., Class A or Mr Z).

Yes, those are free-air plots.

Here's a comment from RW support: "For what it's worth, most of the measurements I took with speakers in a cab, the peak seemed to come in around 110Hz."

Has Jay ever been wrong about something on this forum

Also, from RW support: "But, we can put the impedance measurement in the queue going forward. And we'll start doing this for cabs we pull out of storage and have set up for other reasons. It's not hard to do once you have the circuit built and the cab set up."

 

[R.D.]

Here's a comment from RW support: "For what it's worth, most of the measurements I took with speakers in a cab, the peak seemed to come in around 110Hz."

Has Jay ever been wrong about something on this forum

NOT that I'm aware of ... :!:

 

[dk_ace]

Here's a way to make this simple: set speaker resonant frequency somewhere between 100 and 120 Hz, and fuhgeddaboutit. That figure is within 10% of the resonant frequency every guitar cab I've measured, and anyway it will only have an audible effect if you're using an amp sim with little or no negative feedback (e.g., Class A or Mr Z).

Now that is what I wanted to know!

Thank you Jay Mitchell!

D

 

[VegaBaby]

Here's a way to make this simple: set speaker resonant frequency somewhere between 100 and 120 Hz, and fuhgeddaboutit. That figure is within 10% of the resonant frequency every guitar cab I've measured, and anyway it will only have an audible effect if you're using an amp sim with little or no negative feedback (e.g., Class A or Mr Z).

Here's a comment from RW support: "For what it's worth, most of the measurements I took with speakers in a cab, the peak seemed to come in around 110Hz."

Has Jay ever been wrong about something on this forum

:lol: ... Great !

 

[randocaster]

Cliff mentioned not bothering with this parameter when going FRFR. I'm interested in if this means there's no reason to worry about this when going FR.

 

[joegold]

Electrovoice publishes a spec of 55hz as being the T/S parameter resonant frequency of the EVM-12L.

The actual resonant frequency with the speaker in the cab you're using will be somewhat higher. I'd suggest trying a setting of ~65Hz in the amp sim.

Hey Jay.
What does that "~" symbol in front of 65 mean?
"Approximately"?

 

[joegold]

[quote="Jay Mitchell":xb1iu0x8]
Here's a way to make this simple: set speaker resonant frequency somewhere between 100 and 120 Hz, and fuhgeddaboutit. That figure is within 10% of the resonant frequency every guitar cab I've measured, and anyway it will only have an audible effect if you're using an amp sim with little or no negative feedback (e.g., Class A or Mr Z).

Now that is what I wanted to know!

Thank you Jay Mitchell!

D[/quote:xb1iu0x8]

What thread is that Jay Mitchell quote from?
It doesn't appear to be this thread.

Jay...
If the above is true, then why did you suggest such a low value (65hz) for my 1 X 12 open back EVM-12L cabs?
Maybe you're talking mostly about closed-back cabs in that quote?
Do close-back cabs tend to have a higher SRF than open-back cabs?
Or is the 12L's open air RF just lower than most other guitar speakers?
Or none of the above?