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About HF Resonance

FractalAudio

Administrator
Fractal Audio Systems
Moderator
In the SPKR page of the Amp block are various parameters. I've talked about low-frequency resonance in another post. In this post I will address high-frequency resonance.

As with LF resonance the high output impedance of a tube power amp causes the frequency response to follow the impedance of the speaker. There are two primary components: LF resonance and a high-frequency boost. The HF boost is due to the inductance of the voice coil.

At the frequency where the voice coil reactance is equal to its resistance the impedance will start to rise. If this were a "pure" inductance it would rise at 6 dB per octave. However eddy-current losses in the motor cause this inductance to be "semi-inductive" and the impedance typically rises between 3 and 4 dB per octave. Different brands and models of speakers behave differently. You can look at the spec sheet for a speaker to get an idea as to the behavior of the speaker. The formula for the break frequency is given by f = R / (2*pi*L). For example, if the voice coil inductance is 1 mH and the resistance is 7 ohms then the break frequency would be 7/(6.28*0.001) = 1.1 kHz.

The Axe-Fx II allows you to adjust the virtual voice coil via the HI FREQ and HI RES parameters. The HI FREQ parameter sets the "break" frequency which is the frequency where the inductive reactance equals the voice coil resistance. For most speakers it is around 1000 Hz. It is lower for larger speakers and higher for smaller speakers usually. The HI RES parameter sets the rate at which the impedance increases. The default value of 5.83 is around 3.5 dB per octave.

If you want a smoother sound you can increase HI FREQ and/or decrease HI RES. If you want more highs or "chime" you can decrease HI FREQ and/or increase HI RES. Experiment with different values to get a feel for the response.

Note that the amount of feedback (Damping parameter) will influence the behavior of these controls. With no feedback (Damping = 0) the frequency response follows the impedance curve virtually 1-for-1. As Damping is increased the frequency response flattens and the impedance curve has less influence on the response.

As with all things in the Axe-Fx, use your ears.
 

Narzugon

Power User
If you want a smoother sound you can increase HI FREQ and/or decrease HI RES. If you want more highs or "chime" you can decrease HI FREQ and/or increase HI RES. Experiment with different values to get a feel for the response.

Note that the amount of feedback (Damping parameter) will influence the behavior of these controls. With no feedback (Damping = 0) the frequency response follows the impedance curve virtually 1-for-1. As Damping is increased the frequency response flattens and the impedance curve has less influence on the response.

As with all things in the Axe-Fx, use your ears.
I wish I understood all the pieces but I don't. But I do understand the above which is enough for me. Thanks for including it.
 

tguitar

Inspired
Fractal Audio Said:

扬声器的页中,Amp 块是各种参数。我已经讨论过的低频共振在另一篇文章。在这篇文章中我将处理高频率共振。

如果共振管功率放大器的高输出阻抗导致频率响应要遵循的扬声器的阻抗。有两个主要组件: 如果共振,高频率大大提高。高频刺激是音圈的由于电感。

在语音线圈电抗等于其抵抗的频率,阻抗将开始上升。如果这是"纯粹的"电感将上升 6 分贝每倍频程。然而涡流损失在电机导致此电感通常是"半感应"和阻抗上升 3 和 4 dB 每倍频程之间。不同品牌和型号的发言者的行为不同。你可以看看的规格表,一位发言者要发言的人的行为的想法。由 f 给出的公式为中断频率 = R / (2 * pi * L)。例如,如果语音线圈电感是 1 mH 和抵抗是 7 欧姆,然后中断频率将会 7/(6.28*0.001) = 1.1 千赫。

斧-Fx II 允许您调整虚拟语音线圈通过喜频率和喜 RES 参数。喜频率参数设置的"断裂"频率的频率其中电感电抗等于语音线圈电阻。对于大多数发言者是大约 1000 赫兹。较低的更大的扬声器和高为较小的扬声器通常是。喜 RES 参数设置的阻抗增加的速率。5.83 的默认值是每倍频程约 3.5 dB。

如果你想要一个更平滑的声音你可以增加喜频率和/或减少喜。如果你想要更多的高点或"编钟"你可以减少喜频率和/或增加喜 RES.实验与不同的值来获得感觉的响应。

请注意反馈 (阻尼参数) 的金额将会影响这些控件的行为。无反馈式 (阻尼 = 0) 的频率响应如下的阻抗曲线几乎是 1 对 1。阻尼增加频率响应铺平,以及阻抗曲线具有较少对响应的影响。


Is kinda what this sounds like to me. I just trust that Cliff is the guru and follow his advice. I also definitely need some electronics classes.

In all seriousness though thank you Cliff for your posts. Although I'm being a bit of a shithead , I do learn a TON from you about not only the Axe, but how the real world amp and speaker counterparts work and behave as well.
带着在斧-Fx 的所有东西,使用你的耳朵。

Sent from my iPad using Forum Runner
 

smcrosby

Power User
Not just the speaker page. Cliff is giving us all the pieces in his Cliff Notes, release notes and elsewhere to work the amp, dynamics, tone, speaker, etc., pages we will need to piece the ship together and steer the boat towards tonal nirvana using our ears. Wait until he works in UltraRes and the fog will be lifted! :)
 
Last edited:

PacoCasanovas

Fractal Fanatic
Fractal Audio Said:

扬声器的页中,Amp 块是各种参数。我已经讨论过的低频共振在另一篇文章。在这篇文章中我将处理高频率共振。

如果共振管功率放大器的高输出阻抗导致频率响应要遵循的扬声器的阻抗。有两个主要组件: 如果共振,高频率大大提高。高频刺激是音圈的由于电感。

在语音线圈电抗等于其抵抗的频率,阻抗将开始上升。如果这是"纯粹的"电感将上升 6 分贝每倍频程。然而涡流损失在电机导致此电感通常是"半感应"和阻抗上升 3 和 4 dB 每倍频程之间。不同品牌和型号的发言者的行为不同。你可以看看的规格表,一位发言者要发言的人的行为的想法。由 f 给出的公式为中断频率 = R / (2 * pi * L)。例如,如果语音线圈电感是 1 mH 和抵抗是 7 欧姆,然后中断频率将会 7/(6.28*0.001) = 1.1 千赫。

斧-Fx II 允许您调整虚拟语音线圈通过喜频率和喜 RES 参数。喜频率参数设置的"断裂"频率的频率其中电感电抗等于语音线圈电阻。对于大多数发言者是大约 1000 赫兹。较低的更大的扬声器和高为较小的扬声器通常是。喜 RES 参数设置的阻抗增加的速率。5.83 的默认值是每倍频程约 3.5 dB。

如果你想要一个更平滑的声音你可以增加喜频率和/或减少喜。如果你想要更多的高点或"编钟"你可以减少喜频率和/或增加喜 RES.实验与不同的值来获得感觉的响应。

请注意反馈 (阻尼参数) 的金额将会影响这些控件的行为。无反馈式 (阻尼 = 0) 的频率响应如下的阻抗曲线几乎是 1 对 1。阻尼增加频率响应铺平,以及阻抗曲线具有较少对响应的影响。


Is kinda what this sounds like to me. I just trust that Cliff is the guru and follow his advice. I also definitely need some electronics classes.

In all seriousness though thank you Cliff for your posts. Although I'm being a bit of a shithead , I do learn a TON from you about not only the Axe, but how the real world amp and speaker counterparts work and behave as well.
带着在斧-Fx 的所有东西,使用你的耳朵。

Sent from my iPad using Forum Runner
if you don't understand Cliff's words, get a POD 2.0 - then you understand ;) (no offense, really....)
 

MisterE

Power User
Cliff,

for R, do we have to calculate the total resistance for the cab like for instance for 212 cabs as R/2 when they're in parallel or 2R when they're in series?
 

Funeral

Fractal Fanatic
Thanks Cliff. I appreciate you breaking it down for us.
As Tyler said, its good to know where to start.
Keep up the great work.
 

Noriuky73

Power User
Another little step for us understanding how to find our way to tame the monster ....

Thanks a lot Cliff !!
 

Gamedojo

Power User
Oops... The e130 has a resistance of 6.3ohm not the 7ohm givin in the default equation. 777hz is the new number.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
Oops... The e130 has a resistance of 6.3ohm not the 7ohm givin in the default equation. 777hz is the new number.
Probably not. Technically you need to include the total resistance of the output transformer which is the secondary resistance plus the primary resistance reflected to the secondary. This is usually between 0.5 and 1 ohm. Then there's the resistance of the speaker wires which might be 0.1 ohms or so.

But don't agonize over it. Just because the "real" speaker has those values doesn't mean different values can't sound better.
 

Gamedojo

Power User
NO worries. Not agonizing.

With so much adjustment allowable on the Axefx, I like to set certain things to as close to real as possible before tweaking. everything effects everything, so having a baseline to work from is a good rule of thumb for me.

Probably not. Technically you need to include the total resistance of the output transformer which is the secondary resistance plus the primary resistance reflected to the secondary. This is usually between 0.5 and 1 ohm. Then there's the resistance of the speaker wires which might be 0.1 ohms or so.

But don't agonize over it. Just because the "real" speaker has those values doesn't mean different values can't sound better.
 
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