Closest impedance curve for 2x12 pulsonic greenbacks/twin reverb cab

[unFILTERed]

i have two pulsonic greenbacks. one is 55hz and the other 75hz. both 16ohm. they are loaded in an empty fender twin reverb cabinet and wired stereo. wondering what would be the closest impedance curve for this setup?

 

[unix-guy]

i have two pulsonic greenbacks. one is 55hz and the other 75hz. both 16ohm. they are loaded in an empty fender twin reverb cabinet and wired stereo. wondering what would be the closest impedance curve for this setup?

The impedance curve is based on the cabinet not the speakers as far as I understand.

I think there's a Twin 2x12 in the list... But don't remember for sure.

 

[jon]

It's really an 'interaction' of the cab and speakers. Different cabs with the same speaker will react differently, as will same cabs with different speakers. The impedance changes as a function of the speaker with the cab, for eg a 4×12 with V30s will have a different interaction than the same 4×12 with greenbacks. It will depend on many things, for eg ported vs non ported, speaker excursion, reflections, SPL, etc.

That being said, many curves will be similar to each other, so you can use something similar for great results. Or use just your ears and pick one that sounds good. That always works.

 

[unFILTERed]

The impedance curve is based on the cabinet not the speakers as far as I understand.

I think there's a Twin 2x12 in the list... But don't remember for sure.

I don’t know for sure but i can’t imagine those graph/values being completely independent from the frequency response of the speakers.

For now i am using the 2x12 doubeverb curve, i like the results but i wish i had/could measure the curve of my own cabinet to cure my OCD and have one less thing to think and loose time about

 

[jon]

You're right, they are not independent of the speakers. It's a dynamic interaction which would b very difficult if not impossible to model in its entirety.

FAS has developed a way to capture much more accurately the impedance/frequency curve, which results in a very different, and more interactive, more realistic 'feel'.

They won't be able to model every speaker in every cab, but many guitar speakers are very similar, as are many cabs, so one in the list will likely be close to yours, even if not exactly.

Here's a link to understand how it works:
https://en.m.wikipedia.org/wiki/Electrical_characteristics_of_dynamic_loudspeakers


Here's a quote from that wikipedia article:


Nominal impedance

Diagram showing the variation in impedance of a typical mid-range loudspeaker. Nominal impedance is usually determined at the lowest point after resonance. However, it is possible for the low-frequency impedance to be still lower than this.[1]
Due to the reactive nature of a speaker's impedance over the audio band frequencies, giving a speaker a single value for 'impedance' rating is in principle impossible, as one may surmise from the impedance vs. frequency curve above. The nominal impedance of a loudspeaker is a convenient, single number reference that loosely describes the impedance value of the loudspeaker over a majority of the audio band. A speaker's nominal impedance is defined as:

{\displaystyle Z_{\mathrm {nom} }=1.15\cdot Z_{\mathrm {min} }}

The graph shows the impedance curve of a single loudspeaker driver in free-air (unmounted in any type of enclosure). A home hi-fi loudspeaker system typically consists of two or more drivers, an electrical crossover network to divide the signal by frequency band and route them appropriately to the drivers, and an enclosure that all these components are mounted in. The impedance curve of such a system can be very complex, and the simple formula above does not as easily apply.

 

[unFILTERed]

You're right, they are not independent of the speakers. It's a dynamic interaction which would b very difficult if not impossible to model in its entirety.

FAS has developed a way to capture much more accurately the impedance/frequency curve, which results in a very different, and more interactive, more realistic 'feel'.

They won't be able to model every speaker in every cab, but many guitar speakers are very similar, as are many cabs, so one in the list will likely be close to yours, even if not exactly.

Here's a link to understand how it works:
https://en.m.wikipedia.org/wiki/Electrical_characteristics_of_dynamic_loudspeakers


Here's a quote from that wikipedia article:


Nominal impedance

Diagram showing the variation in impedance of a typical mid-range loudspeaker. Nominal impedance is usually determined at the lowest point after resonance. However, it is possible for the low-frequency impedance to be still lower than this.[1]
Due to the reactive nature of a speaker's impedance over the audio band frequencies, giving a speaker a single value for 'impedance' rating is in principle impossible, as one may surmise from the impedance vs. frequency curve above. The nominal impedance of a loudspeaker is a convenient, single number reference that loosely describes the impedance value of the loudspeaker over a majority of the audio band. A speaker's nominal impedance is defined as:

{\displaystyle Z_{\mathrm {nom} }=1.15\cdot Z_{\mathrm {min} }}

The graph shows the impedance curve of a single loudspeaker driver in free-air (unmounted in any type of enclosure). A home hi-fi loudspeaker system typically consists of two or more drivers, an electrical crossover network to divide the signal by frequency band and route them appropriately to the drivers, and an enclosure that all these components are mounted in. The impedance curve of such a system can be very complex, and the simple formula above does not as easily apply.

thx!

 

[White Light of Death]

You're right, they are not independent of the speakers. It's a dynamic interaction which would b very difficult if not impossible to model in its entirety.

FAS has developed a way to capture much more accurately the impedance/frequency curve, which results in a very different, and more interactive, more realistic 'feel'.

They won't be able to model every speaker in every cab, but many guitar speakers are very similar, as are many cabs, so one in the list will likely be close to yours, even if not exactly.

Here's a link to understand how it works:
https://en.m.wikipedia.org/wiki/Electrical_characteristics_of_dynamic_loudspeakers


Here's a quote from that wikipedia article:


Nominal impedance

Diagram showing the variation in impedance of a typical mid-range loudspeaker. Nominal impedance is usually determined at the lowest point after resonance. However, it is possible for the low-frequency impedance to be still lower than this.[1]
Due to the reactive nature of a speaker's impedance over the audio band frequencies, giving a speaker a single value for 'impedance' rating is in principle impossible, as one may surmise from the impedance vs. frequency curve above. The nominal impedance of a loudspeaker is a convenient, single number reference that loosely describes the impedance value of the loudspeaker over a majority of the audio band. A speaker's nominal impedance is defined as:

{\displaystyle Z_{\mathrm {nom} }=1.15\cdot Z_{\mathrm {min} }}

The graph shows the impedance curve of a single loudspeaker driver in free-air (unmounted in any type of enclosure). A home hi-fi loudspeaker system typically consists of two or more drivers, an electrical crossover network to divide the signal by frequency band and route them appropriately to the drivers, and an enclosure that all these components are mounted in. The impedance curve of such a system can be very complex, and the simple formula above does not as easily apply.

WOW , amazing post dude! Very informative, thanks as well