Why is spring reverb so hard to model?

[la szum]

“Sympathetic harmonics”

Dream Theater Tribute Band!

 

[fretworn]

I know I’m going to regret this, but I’m curious what your rationale for this statement is.

I work in aerospace. Some of the environmental testing that happens on rocket payloads is acoustic testing, to make sure the coupled resonances of payloads with the launch vehicle’s insane noise/SPLs does not destroy the payload.

In general, every rigid structure has a resonant frequency. Guitar cabs will have one too. My old 1950s Danelectro cab vibrates and rattles so much that it’s part of its charm to me.

Even *if* the cab isn’t resonating and transmitting that to the reverb tank, the reverb tank itself as well as the spring(s) inside will also have their own natural frequencies, which will get excited by the sound from the speaker if the speaker is producing those frequencies.

So… how are you so sure that either the sound from the speaker and/or coupled resonance with the cab has no impact on a reverb tank? In my day job experience doing what I do, I would expect it to be affected to some extent.

Buddy of mine does something similar with rocket fuselages, measuring stress and the harmonics along the tube.

 

[SwirlyMaple]

Yup. None of our thoughts, emotions, feelings, or values are real anyways. Just the superficial
mirage cast upon before by a bunch of impersonal neurons dancing in the dark of our craniums.

Meat computers construct reality in a way like nothing else can

 

[dk_ace]

It depends what you're looking for. This example with the "boing!" parameter turned up is fairly surfy and drippy:

Surfy reverb

In about a 2 month span I've done a great deal of homework in creating and tweaking presets for a covers band and doing several gigs. As related in a longer post elsewhere, the consistency/quality of live sound, monitoring options and ease of setup/teardown have been a revelation. I still feel...

forum.fractalaudio.com

I’ll check it out later, thanks. I’m mostly interested in a great amp spring sound, not a surfy outboard thing.

D

 

[la szum]

Meat computers construct reality in a way like nothing else can

Damn neurons constructing poor grammar. Again.

#Blametheneurons!

 

[yeky83]

Unrelated gobbledygookgobbledygookgobbledygookgobbledygookOMGIMINAEROSPACEgobbledygookgobbledygookgobbledygookgobbledygook

Read:

cab resonance increasing with amp volume is certainly a factor

Cab resonance does not increase with amp volume, done.

 

[jay mitchell]

I work in aerospace. Some of the environmental testing that happens on rocket payloads is acoustic testing, to make sure the coupled resonances of payloads with the launch vehicle’s insane noise/SPLs does not destroy the payload.

It's known as "order of magnitude." Rocket engines, turbines, and the like produce enough SPL to drive air beyond its linear range. Similarly, mechanical vibrations of the magnitude encountered in spacecraft could easily push structural components well beyond their linear ranges.

In general, every rigid structure has a resonant frequency.

That's an oversimplification. Rigid structures can have multiple resonant frequencies. And what you describe above may or may not be related to resonant frequencies.

Guitar cabs will have one too.

Perhaps multiples as well. FYI, those frequencies don't change with the magnitude of vibration. That was the gist of my comment.

My old 1950s Danelectro cab vibrates and rattles so much that it’s part of its charm to me.

Structural deficiencies cause rattles. A standard technique in the sound system commissioning process in IMAX theaters is to excite the subbass array with a sinusoid from a signal generator and to very slowly sweep its frequency through the band of operation. When vibration or rattling was audible, the technician would then find the source - which often required a trip up the catwalks and hanging from a safety harness - and tighten or otherwise secure the offending hardware.

Even *if* the cab isn’t resonating and transmitting that to the reverb tank, the reverb tank itself as well as the spring(s) inside will also have their own natural frequencies, which will get excited by the sound from the speaker if the speaker is producing those frequencies.

You're conflating "sympathetic vibration" with "resonance." They are two different things. The springs in reverb tanks are mounted at either end via isolating springs, which have a low spring constant. The frequency of mechanical resonance of the resulting spring/mass system falls below the frequencies it will be subjected to from the amp/speaker/cab.

So… how are you so sure that either the sound from the speaker and/or coupled resonance with the cab has no impact on a reverb tank?

How did you come to believe I said that? I made no such statement.

In my day job experience doing what I do, I would expect it to be affected to some extent.

This may be a problem of misuse of nomenclature, then. Cabinet vibration is not the same as cabinet resonance. Cabinet vibration will increase with volume. Cabinet resonance will not.

 

[Stone]

Jeez, Cliff must be having an aneurysm at this point if he has read everything so far
I know nothing of fender spring reverbs, but is there not a fender pedal that can do the same
Just add it to you modeler if its a must

 

[SwirlyMaple]

SwirlyMaple said:
Unrelated gobbledygookgobbledygookgobbledygookgobbledygookOMGIMINAEROSPACEgobbledygookgobbledygookgobbledygookgobbledygook

I included the fact that I work in aerospace to make it clear that I have real-world experience with these concepts and the physics behind them. You included my quote in this modified way to make it clear you are emotionally reactive and might be resonating at this very moment.

Read:

Cab resonance does not increase with amp volume, done.

Vibration resulting from cab resonance does increase with volume, though, which is obviously what he meant. Jay honed in on what he said to ignore the clear intent and be as pedantic as possible, as usual.

 

[SwirlyMaple]

It's known as "order of magnitude." Rocket engines, turbines, and the like produce enough SPL to drive air beyond its linear range. Similarly, mechanical vibrations of the magnitude encountered in spacecraft could easily push structural components well beyond their linear ranges.


That's an oversimplification. Rigid structures can have multiple resonant frequencies. And what you describe above may or may not be related to resonant frequencies.


Perhaps multiples as well. FYI, those frequencies don't change with the magnitude of vibration. That was the gist of my comment.


Structural deficiencies cause rattles. A standard technique in the sound system commissioning process in IMAX theaters is to excite the subbass array with a sinusiod from a signal generator and to very slowly sweep its frequency through the band of operation. When vibration or rattling was audible, the technician would then find the source - which often required a trip up the catwalks and hanging from a safety harness - and tighten or otherwise secure the offending hardware.


You're conflating "sympathetic vibration" with "resonance." They are two different things. The springs in reverb tanks are mounted at either end via isolating springs, which have a low spring constant. The frequency of mechanical resonance of the resulting spring/mass system falls below the frequencies it will be subjected to from the amp/speaker/cab.

How did you come to believe I said that? I made no such statement.

This then may be a problem of misuse of nomenclature, then. Cabinet vibration is not the same as cabinet resonance. Cabinet vibration will increase with volume. Cabinet resonance will not.

So, to summarize, instead of the back-and-forth that stimulates you so much:

• Reverb tanks can indeed be affected by the output of a combo amp and their placement within the cab
• This is clearly what @la szum was conveying to everyone else, but the opportunity to be pedantic is some people's cocaine

Glad we sorted that out.

 

[yeky83]

I included the fact that I work in aerospace to make it clear that I have real-world experience with these concepts and the physics behind them. You included my quote in this modified way to make it clear you are emotionally reactive and might be resonating at this very moment.


Vibration resulting from cab resonance does increase with volume, though, which is obviously what he meant. Jay honed in on what he said to ignore the clear intent and be as pedantic as possible, as usual.

real-world experience with these concepts and the physics behind them

The man comes and very nicely explains some stuff that should pique your interest and maybe even help you look a little smarter at your work too, and all you have are insults.

 

[fretworn]

So, to summarize, instead of the back-and-forth that stimulates you so much:

• Reverb tanks can indeed be affected by the output of a combo amp and their placement within the cab
• This is clearly what @la szum was conveying to everyone else, but the opportunity to be pedantic is some people's cocaine

Glad we sorted that out.

I don’t think he was being pedantic. I think he was being precise.

That being said, there are ways to message ideas and then there’s tactics that will always foment mutually-assured destruction results; despite the ivory tower fortifications.

 

[la szum]

So, to summarize, instead of the back-and-forth that stimulates you so much:

• Reverb tanks can indeed be affected by the output of a combo amp and their placement within the cab
• This is clearly what @la szum was conveying to everyone else, but the opportunity to be pedantic is some people's cocaine

Glad we sorted that out.

Mmmmm..... cocaine.....

 

[SwirlyMaple]

real-world experience with these concepts and the physics behind them

The man comes and very nicely explains some stuff that should pique your interest and maybe even help you look a little smarter at your work too, and all you have are insults.

I am already aware of everything he said in his reply. I studied this stuff for years and have two degrees in engineering, and aerospace design+analysis+fabrication+testing have all been my day job since I was 22. One of the most common tests done on spaceflight hardware is vibration testing, both by mechanical attachment to a vibration table as well as acoustic testing. I have been involved in the design and analysis prior to these tests, analyzing the structures and their vibrational modes, as well as carrying out the tests and analyzing the post-test data more times than I can even remember.

I chose not to respond line-by-line because I've made that mistake before. We've already gotten to the root of what actually mattered: is a reverb tank affected by being mounted inside a cab? Yes. The rest is just bait.

 

[la szum]

You're conflating "sympathetic vibration" with "resonance." They are two different things. The springs in reverb tanks are mounted at either end via isolating springs, which have a low spring constant. The frequency of mechanical resonance of the resulting spring/mass system falls below the frequencies it will be subjected to from the amp/speaker/cab.

I was the erroneous conflater. I knew it had to be one or the other way of describing it. I chose the wrong one.

Appreciate the detailed breakdown.


Knowing me, I'll probably be erroneous again and bet wrong. It happens. Just like the spring reverb tank
reacts differently in a Super Reverb the louder I turn it up.

 

[jay mitchell]

I am already aware of everything he said in his reply. I studied this stuff for years and have two degrees in engineering, and aerospace design+analysis+fabrication+testing have all been my day job since I was 22.

That's quite an impressive CV. Given your education and experience, you should have immediately recognized the significance of one of my prior statements, repeated here for your convenience:

"The springs in reverb tanks are mounted at either end via isolating springs, which have a low spring constant. The frequency of mechanical resonance of the resulting spring/mass system falls below the frequencies it will be subjected to from the amp/speaker/cab.

To refresh what should be your memory of mechanical design for vibration isolation, this substantially reduces, likely to a negligible level, the effect of vibration from frequencies that lie above the system's resonant frequency, IOW frequencies produced by electric guitar.

is a reverb tank affected by being mounted inside a cab?

See above and give it a moment's thought. It might be, but only slightly. Seems the makers of reverb tanks knew what they were doing....

 

[yeky83]

I am already aware of everything he said in his reply. I studied this stuff for years and have two degrees in engineering, and aerospace design+analysis+fabrication+testing have all been my day job since I was 22. One of the most common tests done on spaceflight hardware is vibration testing, both by mechanical attachment to a vibration table as well as acoustic testing. I have been involved in the design and analysis prior to these tests, analyzing the structures and their vibrational modes, as well as carrying out the tests and analyzing the post-test data more times than I can even remember.

I chose not to respond line-by-line because I've made that mistake before. We've already gotten to the root of what actually mattered: is a reverb tank affected by being mounted inside a cab? Yes. The rest is just bait.

Or you baited him, cus with all that experience and knowledge when someone says "resonance increases with amplitude" it should've stuck out to you like a sore thumb. How could you not have noticed that's obviously what Jay was correcting? Either you don't know your stuff or you baited him, get outta here lol.

 

[Mongillo19]

 

[PLX]

"The springs in reverb tanks are mounted at either end via isolating springs, which have a low spring constant. The frequency of mechanical resonance of the resulting spring/mass system falls below the frequencies it will be subjected to from the amp/speaker/cab.

To refresh what should be your memory of mechanical design for vibration isolation, this substantially reduces, likely to a negligible level, the effect of vibration from frequencies that lie above the system's resonant frequency, IOW frequencies produced by electric guitar.


See above and give it a moment's thought. It might be, but only slightly. Seems the makers of reverb tanks knew what they were doing....

 

[la szum]

It depends what you're looking for. This example with the "boing!" parameter turned up is fairly surfy and drippy:

Surfy reverb

In about a 2 month span I've done a great deal of homework in creating and tweaking presets for a covers band and doing several gigs. As related in a longer post elsewhere, the consistency/quality of live sound, monitoring options and ease of setup/teardown have been a revelation. I still feel...

forum.fractalaudio.com

Now I know there is a "Boooing" parameter. Thank you. I never would have looked!