V6 firmware: Time to Release the Monster - Speaker Resonance Page

[Scott Peterson]

I can't imagine how a cabinet could affect the impedance curve of an element. It affects the resonant frequency though.

The resonant frequency of a cab is already there, even in the IR's, and it shouldn't be confused with the impedance simulation in the speaker tab. That's why the theory of adding 10 Hz to the rated speaker impedance didn't make sense to me. It is exactly this rated speaker impedance that should be set in the speaker tab. If one wants to simulate the real world, that is!

Of course, using ears kinda important. I'm just commenting on the theory presented

From my (non-scientific) viewpoint - every cab sounds different with every amp. Each amp reacts differently - though remarkably similar at the same time - to the cab. Switch the speakers in the cab (in the analog world) and the same cab *feels* and sounds differently. We can control and tune that in with the Axe-FX II.

So what i am doing is using data that is available - right or wrong - to start the *process* to dial things in. These are starting points and I wanted some way to at least *begin* that process

I am about: a) results: I know what I want. I know what I like; b) method: a way to achieve the results I want consistently and efficiently. Once I've achieved that to my own satisfaction, I try to share it (just as other folks do). My way is not the right way, not the only way, not a better way - it is just my way. IMHO, it's right, it's better. But that's subjective - folks are invited to try them and form their own opinions. And if they don't agree with me; at least I have sparked some interest or different approaches for folks to try.

 

[javajunkie]

I can't imagine how a cabinet could affect the impedance curve of an element. It affects the resonant frequency though.

The resonant frequency of a cab is already there, even in the IR's, and it shouldn't be confused with the impedance simulation in the speaker tab. That's why the theory of adding 10 Hz to the rated speaker impedance didn't make sense to me. It is exactly this rated speaker impedance that should be set in the speaker tab. If one wants to simulate the real world, that is!

Of course, using ears kinda important. I'm just commenting on the theory presented

No argument with what you are getting at. I'll ask on TGP.

 

[Trazan]

I edited my last post, didn't see these new ones being posted!

I'm thinking it depends on whether one uses IR's or real cabs. A real cab will shift the low resonant curve in the speaker tab some 10 Hz up. The IR won't, and it has been captured with a ss amp and has no resonance.

IOW, this low resonant curve should be set some 10 Hz above using IR, and at the elements rated curve when using real cabs.


That being said. IS the speaker tab in fact just EQ'ng the signal?

 

[skintone1]

So what i am doing is using data that is available - right or wrong - to start the *process* to dial things in. These are starting points and I wanted some way to at least *begin* that process

And if they don't agree with me; at least I have sparked some interest or different approaches for folks to try.

Scott,
Yes you have certainly sparked interest, and stimulated me to go and read all those speaker resonant frequency pages on Google yesterday !
Now, I have a question just designed to increase my poor understanding of this concept , nothing else mind...
Would this really make a difference to what the audience hears in a live situation?
It seems to me the resonance you achieve means the sound waves in the air of the room move with greater amplitude, but surely, that must change depending on:
1. the size of the room
2. how many bodies are packed into the room
3. the configuration , makeup of the room ( tiled floor, wooden floor etc)
4. What other instruments are playing , and the resonance of their sound?

Am I on the right track, or completely missing the point?

 

[javajunkie]

I edited my last post, didn't see these new ones being posted!

I'm thinking it depends on whether one uses IR's or real cabs. A real cab will shift the low resonant curve in the speaker tab some 10 Hz up. The IR won't, and it has been captured with a ss amp and has no resonance.

IOW, this low resonant curve should be set some 10 Hz above using IR, and at the elements rated curve when using real cabs.


That being said. IS the speaker tab in fact just EQ'ng the signal?

Here is what jay said regarding the quote I referred to earlier.
"All electric motors - including loudspeakers - function in reverse (IOW, as generators) as well. You can actually use a cone transducer as a microphone. For this reason, anything that affects the mechanical motion of a transducer also affects theelectrical load (aka "impedance") that it presents to the amplifier

As I pointed out earlier in this thread, placing a cone transducer in a sealed box adds to the spring constant of the suspension. This has the effect of increasing the resonant frequency, which is the frequency at which the electrical impedance reaches its peak value. Internal reflections in an undamped cab can also cause small artifacts in the impedance vs. frequency characteristic of a speaker. As an informational item, the term "resonance" is woefully misunderstood in this context. You cannot identify the "resonant" frequency of a speaker/cab combination via any listening exercise. In most cases, there is no amplitude response peak at the resonant frequency. Impedance vs frequency information is not available from the IR of a speaker, either. It is a separate data set without which the detailed interactions between an amp and speaker - which profoundly affect the sound and feel of guitar amps - cannot be accurately simulated."

 

[Scott Peterson]

Scott,
Yes you have certainly sparked interest, and stimulated me to go and read all those speaker resonant frequency pages on Google yesterday !
Now, I have a question just designed to increase my poor understanding of this concept , nothing else mind...
Would this really make a difference to what the audience hears in a live situation?
It seems to me the resonance you achieve means the sound waves in the air of the room move with greater amplitude, but surely, that must change depending on:
1. the size of the room
2. how many bodies are packed into the room
3. the configuration , makeup of the room ( tiled floor, wooden floor etc)
4. What other instruments are playing , and the resonance of their sound?

Am I on the right track, or completely missing the point?

Totally different stuff. The room, audience and such have no factor on how the amp and cab interact unless it has something to do with the speaker... you are misapplying the resonance of a frequency versus the impedance resonance of the power amp/transformer/speaker. I think??

 

[Stratoblaster]

Great thread, and thanks to Scott and Jay for their insights and work!

I measured the low resonant frequency of my 1982 Marshall 4x12 with G12-65 speakers a while ago and the resonant frequency is 115Hz.

I'm going to try to find time to measure the high frequency peak, Q of both peaks, and the overall impedance across the range since this thread has made me curious...

I used a more accurate method and test gear to measure cab resonance, and the Marshall resonant frequency is 110Hz, not 115Hz. Doh!

Using this method Measuring Loudspeaker Driver Parameters I measured the Q and resonant frequencies of my:

-1982 Marshall 4x12 G12-65 8 Ohm cabinet
-Orange Rocker 30 1x12 Celestion V30 16 Ohm open back

...and got the following results:

4x12:
Resonant Peak: 110Hz
Q: 1.55

V30:
Resonant Peak: 63Hz
Q: 0.72

One thing I'm not sure about is the what the units represent for the "Low Resonance" parameter on the AxeFX, but I suspect it's the ratio between Zmax and Znom. If that's the case:

Low Resonance:
4x12: 4.67
V30: 8.48

Cliff can you elaborate on what the numbers for the Low Resonance parameter represent?

 

[3Dhuman]

Scott,

I haven't posted anything in quite a while. I got home tonight from work and checked out the forum... came across this thread... tried out your settings. In the half hour I've been playing around since making these adjustments, I smiled. A lot.

You have given me the the 2 biggest tips since I got this fantastic machine. The first was the NF/FF mix trick which changed everything for me. And now this!

I play live almost exclusively... this new trick is the bee's knees for loud/live tone and feel! You have no idea how grateful I am for your willingness to share these great discoveries.

Thank you (and Jay too)!

 

[Trazan]

Here is what jay said regarding the quote I referred to earlier.
"All electric motors - including loudspeakers - function in reverse (IOW, as generators) as well. You can actually use a cone transducer as a microphone. For this reason, anything that affects the mechanical motion of a transducer also affects theelectrical load (aka "impedance") that it presents to the amplifier

Ah, that makes sense!

You cannot identify the "resonant" frequency of a speaker/cab combination via any listening exercise. In most cases, there is no amplitude response peak at the resonant frequency. Impedance vs frequency information is not available from the IR of a speaker, either. It is a separate data set without which the detailed interactions between an amp and speaker - which profoundly affect the sound and feel of guitar amps - cannot be accurately simulated."

Meaning, people are identifying room modes, source freq content etc. Maybe the wiki should be edited?

I'm still curious what that speaker tab actually does. Someone care to measure if it's an eq? 8)

 

[barhrecords]

I'm still curious what that speaker tab actually does. Someone care to measure if it's an eq? 8)

IIRC, the parameters on that page will influence the power tube code in the amp model. The power tube breakup changes based on the load the power tubes *see* from the output transformer -> speaker.

 

[shasha]

I haven't read through all of this, but as usual it seems to have taken a turn towards high level geek-dom.

I'm not an expert on anything and know enough about electronics to be dangerous and enough about acoustics to sound like an idiot, but I do think that I could see where the cabinet could effect the impedance. We're talking about a physical device in the speaker motor. The voice coil is going to move a certain way based on frequency and amplitude of the signal. Because its a coil it will have inductive reactance which is affected by frequency. If the cabinet changes the resonant frequency of the speaker then the reactance has to shift. Reactance and impedance would both be shifted as a result since both are frequency specific.

I also think that because the frequency response is based a lot on how easily the speaker recreates a specific frequency that the cabinet will create its own physical resistance based on how its designed and tuned. The electrical impedance may change with a change in physical resistance from back pressure of the cabinet. Its still a load and even though the coil itself isn't changing in value the amount of work needed to make it move could. It may not change in terms of electrical value, but the output and frequency response acoustically could still give the impression as if it was changed electrically.

So the big question is whether changing the amount of physical resistance of the voice coil because of the design of the cabinet does in fact change the electrical impedance of the driver itself and I think that it could.

This is where my lack of higher education shows. So for me I just turn a few parameters here and there to see what each sounds like and then when I find what I like I mess with that one more.

But I would definitely like to know more based on the technical aspect. I just wonder if it's a bit beyond the scope of this thread.

 

[3Dhuman]

OK... it is now some hours (and a night's sleep) since my last post above (which was the first post in quite a while that I felt compelled to make).

I've been playing since waking up this morning. Period.

Now, here I am... logged back into this forum, compelled to make this second post... which is:

I don't care what is going on with speaker-impedance-resonant-freguency-graph-curve-kitchen-sink-space-shuttle-NASA! Am I going to google/read about these things? Probably. Are Scott and Jay and Cliff smarter than me? Definitely. Do these settings/concepts sound more natural/real for loud live tone/feel? Absolutely!

Have I used too many/not enough slashes/-dashes while wording/typing my thoughts-feelings? You bet.

Am I now going to log off so I can continue to molest/strangle my guitar's neck? Yes...

Goodbye.

 

[javajunkie]

I haven't read through all of this, but as usual it seems to have taken a turn towards high level geek-dom.

I'm not an expert on anything and know enough about electronics to be dangerous and enough about acoustics to sound like an idiot, but I do think that I could see where the cabinet could effect the impedance. We're talking about a physical device in the speaker motor. The voice coil is going to move a certain way based on frequency and amplitude of the signal. Because its a coil it will have inductive reactance which is affected by frequency. If the cabinet changes the resonant frequency of the speaker then the reactance has to shift. Reactance and impedance would both be shifted as a result since both are frequency specific.

I also think that because the frequency response is based a lot on how easily the speaker recreates a specific frequency that the cabinet will create its own physical resistance based on how its designed and tuned. The electrical impedance may change with a change in physical resistance from back pressure of the cabinet. Its still a load and even though the coil itself isn't changing in value the amount of work needed to make it move could. It may not change in terms of electrical value, but the output and frequency response acoustically could still give the impression as if it was changed electrically.

So the big question is whether changing the amount of physical resistance of the voice coil because of the design of the cabinet does in fact change the electrical impedance of the driver itself and I think that it could.

This is where my lack of higher education shows. So for me I just turn a few parameters here and there to see what each sounds like and then when I find what I like I mess with that one more.

But I would definitely like to know more based on the technical aspect. I just wonder if it's a bit beyond the scope of this thread.

read the quote from jay that I posted. It explains it.

 

[notalemming]

Are any of you that really like these settings playing through guitar cabs? For me, the hi res setting makes it way too dark. I can see how this would help make a FRFR system sound more natural but for guitar cabs, not so good.

 

[shasha]

read the quote from jay that I posted. It explains it.

Cool, so I'm not a complete idiot.

 

[Narzugon]

It's funny. The Axe has so many features/tools that I find myself putting features on the back burner. Putting a feature on the back burner with the intent of getting back to it but in the mean time playing/experimenting with another feature.

Thanks for the work Scott/Jay. It forced me to dig further into that section and understand a few things that I had "put on the back burner". For me, much like Vegababy, I monitor mainly through studio monitors but I also have a pair of QSC HPR122i's. So I setup a reamp'd track to loop and went to work.

With just your suggested reference settings, the QSC's @100DB were much improved. It tamed the harsh highs, smoothed the mids and tightened the low end. I tweaked and read for about an hour and in the end the settings were very close to your starting points (do you play through HPR's by chance?).

As expected, opposite results with the studio monitors at about 95DB. So I started from scratch with entire Amp block speaker page. After another hour of tweaking/reading found that I was really close to the factory settings but with a few small improvements based on personal preference.

Was a good learning experience all around.

 

[Stratoblaster]

It's funny. The Axe has so many features/tools that I find myself putting features on the back burner. Putting a feature on the back burner with the intent of getting back to it but in the mean time playing/experimenting with another feature.

I too put a lot of stuff on the backburner since the firmware has been fundamentally changing since the II came out, but Scott's findings and explorations in this post have inspired me to look into this parameter in some depth and allocate time to really get into it.

I find the suggested starting points work better and sound/feel more 'speaker-like' for all of my amps, from clean to higain. The picking and volume control dynamics/breakup are more in 'my zone'; Jay mentions that effect on the TGP and I agree fully...great feel.

My IR combos I was using have changed since the 'new' impedance curve makes a big difference, and I'm preferring a NF/FF mix vs the FF/FF cab I was using before.

I've played with many cabs/amps combinations with Scott's/Jay's impedance curve over the last couple of days and compared presets with my existing ones with stock, or lightly tweaked, curves and can say that my starting defaults will now be the settings in the OP.

 

[scrmnglspl]

I just tried this on my medium and high gain patches. Without gushing to much, this was a major break through for me. I started with Scott's base setting and adjusted just a little to taste. I used a combination of the OH Bogner V31 SM57 4 as the NF, and the OH Bogner V31 Room 3 as the "FF" (I'm not sure if this is a true Far Field or not, I'm a little sketchy on the definition).

Whatever combo you use, you owe it to yourself to try this.

 

[xfigox]

These settings have really helped me alot. I'm a high gain kinda guy so the tweak has really helped remove the sizzle and harsh high end from the tone, what I really liked was the harsh attack of the notes have been significantly reduced.

When I used to do reamping, I felt that the guitars were always sticking out too much, even during heavy chuggachugga palm mutes, there's just too much attack. Now with the tweak I find the guitars sitting much better in the mix, it can sound bright but not harsh, which is something I've been struggling to achieve for a long time until now!

I could also hear a significant improvement in tone when using headphones, sounds so much smoother and 'nicer' to play on!

 

[Scott Peterson]

Cool guys - really glad some folks are digging it. I'm totally having a ball playing; sounds fantastic, blooms, and everything from big chords to single note lines have bloom and 'weight' without anything feeling 'stiff' or 'hyper real' if you get my drift... I just feel very connected to the guitar when I am playing... and it's noticeable to me even in the moment. Crunch stuff crunches right. Clean stuff carries more 'musical traction'.

Had some great gigs the past few weeks where everything was just sitting so well. I'm happy, I am playing inspired and it's really cool to see guys checking it out and digging it. Even the guys that don't like it - thanks for trying it.

I'm digging it.