displacement as a function of cabinet preferences

[dspellman]

Originally Posted by makohund

Given a choice between higher surface area but low excursion, or smaller surface area but higher excursion, which would you choose, and why?

Or would one consider the question irrelevant, as there is not enough information?

I'd have to go with the latter -- there's not enough information.

As a guitar/keyboard player, I worked with a lot of bass players who carted around refrigerators and half-fridges. When I was asked to play bass on a couple of projects (and needed a rig) I assumed that's what I'd be working with. In the end, after quite a bit of due diligence, I decided to go with a pair of 1x15 (plus mid/tweeter drivers) cabs that are significantly lower, lighter, louder, cleaner and less directional. Personal preference.

[dhsierra1]

Originally Posted by 1958Bassman

FWIW, the distance a cone moves due to a specific amount of force is called the 'compliance'.

No

Compliance is the inverse of impedence, in the material science world is the equivalent of modulus of elasticity, which is a function of frequency. The "travel" is dependent on a function of both the frequency and power applied, among other things.......

[makohund]

Understood, note in my profile I'm running a slightly smaller version of the same.

What kicked this off was hearing somebody say they'd always take greater surface area over greater xmax, then later implying they'd make that same choice even if it sacrificed a lot of Vd. I was curious about the reasoning behind that, but the thread got snuffed before I could ask.

So figured I'd just ask everybody what they thought. And I did get some good responses, including what seems to be a reasonable reason for that choice, at least when Vd is otherwise equal. Cool beans.

Now I'm curious about how much impact that difference can make, and whether there are cons that come with it.

[Codger]

Originally Posted by makohund

Given a choice between higher surface area but low excursion, or smaller surface area but higher excursion, which would you choose, and why?

Stated in those terms, if I didn't have much power I'd look at large cone area due to that configuration's better efficiency. If I was concerned about the radiation pattern and could make up the loss of efficiency with increased electrical power then I'd look at a small area solution.

I chose the second, because I am concerned with size, weight and radiation pattern.

Originally Posted by dhsierra1

No
Compliance is the inverse of impedence, in the material science world is the equivalent of modulus of elasticity, which is a function of frequency. The "travel" is dependent on a function of both the frequency and power applied, among other things.......

AFAIK the units for compliance are meters per newton. There is no frequency component.

[KJung]

Originally Posted by makohund

Not impossible, as evidenced by the existence of replies.

Yes, they will sound different. Yes, every little variable will change sound, and we're not looking at enough for a whole picture. I'm talking purely theoretical here, out of intellectual curiosity... not actually cab shopping or anything.

But I'm curious about the impact of just this one aspect, and the tradeoffs between the approaches. Yes, no replacement for displacement. But displacement is three dimensions, Assuming we're dealing with speaker cones, the variables for displacement (and displacement alone) are:

1 - Surface area of the cones
2 - number of cones
3 - xmax

And perhaps to some degree "arrangement" if multiples are in play.

Basically... Bigger bore, or bigger stroke? Or "negligible difference, if equal other variables will take precedence".

Craig.P's thing on air impedence matching is very interesting. Fdeck's comment on on greater surface area likely resulting in lowered beaming frequency (and inherent tone & performance differences that brings) is pretty insightful.

I agree with most that practicality wins, and likely points to higher xmax (and the smaller/lighter package it usually brings). And also subscribe to cl400peavey's "gimme lots of both" philosophy.

Which makes Craig.p's take on it all the more interesting to me... Not something I've thought of or considered before, thanks. Anyone else have any more insight into how much weight that difference carries in the land of tradeoffs that is cab design?

Well, here is yet another example, since it is more about tone than 'volume'.

My two 'small gig' cabs are a Thunderchild112 and a Bergantino AE210. This is a classic example (IMO) of what I am talking about.

Both are about the same size and weight. The Thunderchild has a PA type 12" woofer with massive mechanical spec's, and a relatively low crossed over horn that is for all practical purposes, a mid driver. The Bergantino is an 'offset but mostly vertical' high quality 210 with tweeter.

They both sound so totally different that you can't, in any way that I've found, EQ them to sound anywhere near the same.

The Thunderchild goes deeper, has ZERO distortion in the midrange, a very even, relaxed upper mid response (no bump whatsoever) and is relatively inefficient.

The Bergantino has very high quality 10" drivers, does not go as low, has a glorious, warm midrange response, a bit of grind up top, and a very nice, open upper treble extension that is in no way sizzly or harsh.

The maximum volume for both is virtually identical, but it takes about twice the wattage to get there with the Thunderfunk112 (4ohms) versus the Berg AE210 (8ohms)... i.e., they reach the same maximum volume with the same solid state head running at the different wattage/impedance levels.

Off axis performance is very similar between the two.

So, one has a single, massive, high excursion driver, and the other has two 'moderate excursion' drivers. They both sound great and deliver their inherent tones at about the same maximum volume, adjusted for the different efficiencies.

Which 'design' is best Depends on the tone you are going for. I love them both for different reasons, and both fit nicely and differently in my gigging contexts. There is a beauty to the open, relatively neutral, deep voicing of the Thunderchild, with virtually no 'distortion' of the midrange. There is also something beautiful in the punchy, focused, mid present, warm voicing of the Berg, with some pleasant break-up at the top of the drivers response that spreads out in the room quite nicely.

So, it is ALL about tonality once you get to high quality designs like this, and it all depends on getting to the tone you prefer most efficiently.

IMO and LOTS of IME on this, given my years and decades of gigging both 'schools of thought and designs', starting with the early three way designs (EA VL series and Acme) through the more current mid driver designs (fEARful, Thunderchild), and also many more 'traditional' but uber quality traditional two way executions (primarily Bergantino these days) with more full range/midrange focused woofers.

[dhsierra1]

Originally Posted by Codger

AFAIK the units for compliance are meters per newton. There is no frequency component.

there is both static and dynamic compliance in physics.

[barryaudio]

Originally Posted by dhsierra1

Compliance is the inverse of impedence

Admittance??

[dhsierra1]

Originally Posted by barryaudio

Admittance??

You mean Six Organs of Admittance? Good band

Seriously, though, this is what I'm trying to explain, albeit not doing it very well.....

http://en.wikipedia.org/wiki/Mechanical_impedance

So the analogy is that the inverse of resistance in any form is compliance, be it electrical or mechanical. And dynamically (a function of frequency/A.C.) or static/linearly (steady state/D.C).

[barryaudio]

Originally Posted by dhsierra1

You mean Six Organs of Admittance? Good band

Seriously, though, this is what I'm trying to explain, albeit not doing it very well.....

http://en.wikipedia.org/wiki/Mechanical_impedance

So the analogy is that the inverse of resistance in any form is compliance, be it electrical or mechanical. And dynamically (a function of frequency/A.C.) or static/linearly (steady state/D.C).

I'm familiar with admittance as the inverse of impedance in impedance spectroscopy. Conductance being the inverse of the steady state (DC conductivity). Looks like that wiki link says the same thing?? The use of the term compliance is not one that I've seen before as you describe. Anyway, not incredibly relevant but I can appreciate a discussion on the lexicon. thanks

[barryaudio]

IDK, comparing Thunderchild112 and a Bergantino AE210 is not the best comparison for this particular thought experiment. One uses an LF speaker and the other a pair of full range. They are also totally different designs up and down the frequency spectrum, so how can one compare the tone differences with regards to speaker size? That's like saying my '70 Fender Jazz sounds different than my Dingwall ABZ5, so 4 string and 5 string basses must sound different.

regarding off-axis: a 10" speaker will have a beaming limit of about 1.6kHz, so I would challenge that the TC would have better off-axis performance due to the tweeter bearing the load of upper mids and highs.

"maximum volume": I think you are actually referring to sensitivity? I would believe that the 210 would have a higher sensitivity anyway for a few reasons: (a) they use full range speakers which in general are more sensitive (b) 2x10 is 40% more surface area than 1x12 (c) even with the same size speaker, typically the tradeoff for higher xmax is lower sensitivity. Without knowing the xmax of the 10s in the Berg cab, it would be difficult to model "maximum volume".

[dhsierra1]

Originally Posted by barryaudio

The use of the term compliance is not one that I've seen before as you describe. Anyway, not incredibly relevant but I can appreciate a discussion on the lexicon. thanks

Likewise, no worries, just trying to clarify a point made by someone else earlier in the thread

[ThisBass]

Originally Posted by dhsierra1

You mean Six Organs of Admittance? Good band

Seriously, though, this is what I'm trying to explain, albeit not doing it very well.....

http://en.wikipedia.org/wiki/Mechanical_impedance

So the analogy is that the inverse of resistance in any form is compliance, be it electrical or mechanical. And dynamically (a function of frequency/A.C.) or static/linearly (steady state/D.C).

No

TSP compliance don't refers to any explicit frequencies >0 or something like frequency band.

electrical analogy of impedance
By the other hand (of course) every drivers current consumption is calculated by Z nominal impedance, or Zmin.
But the truth is a different animal very often.

[dhsierra1]

Originally Posted by ThisBass

No

TSP compliance don't refers to any explicit frequencies >0 or something like frequency band.

my explanation of compliance wasn't about T/S compliance, sorry for the confusion.

[makohund]

Originally Posted by KJung

Well, here is yet another example, since it is more about tone than 'volume'.

My two 'small gig' cabs are a Thunderchild112 and a Bergantino AE210. This is a classic example (IMO) of what I am talking about.

Both are about the same size and weight. The Thunderchild has a PA type 12" woofer with massive mechanical spec's, and a relatively low crossed over horn that is for all practical purposes, a mid driver. The Bergantino is an 'offset but mostly vertical' high quality 210 with tweeter.

They both sound so totally different that you can't, in any way that I've found, EQ them to sound anywhere near the same.

The Thunderchild goes deeper, has ZERO distortion in the midrange, a very even, relaxed upper mid response (no bump whatsoever) and is relatively inefficient.

The Bergantino has very high quality 10" drivers, does not go as low, has a glorious, warm midrange response, a bit of grind up top, and a very nice, open upper treble extension that is in no way sizzly or harsh.

The maximum volume for both is virtually identical, but it takes about twice the wattage to get there with the Thunderfunk112 (4ohms) versus the Berg AE210 (8ohms)... i.e., they reach the same maximum volume with the same solid state head running at the different wattage/impedance levels.

Off axis performance is very similar between the two.

So, one has a single, massive, high excursion driver, and the other has two 'moderate excursion' drivers. They both sound great and deliver their inherent tones at about the same maximum volume, adjusted for the different efficiencies.

Which 'design' is best Depends on the tone you are going for. I love them both for different reasons, and both fit nicely and differently in my gigging contexts. There is a beauty to the open, relatively neutral, deep voicing of the Thunderchild, with virtually no 'distortion' of the midrange. There is also something beautiful in the punchy, focused, mid present, warm voicing of the Berg, with some pleasant break-up at the top of the drivers response that spreads out in the room quite nicely.

So, it is ALL about tonality once you get to high quality designs like this, and it all depends on getting to the tone you prefer most efficiently.

IMO and LOTS of IME on this, given my years and decades of gigging both 'schools of thought and designs', starting with the early three way designs (EA VL series and Acme) through the more current mid driver designs (fEARful, Thunderchild), and also many more 'traditional' but uber quality traditional two way executions (primarily Bergantino these days) with more full range/midrange focused woofers.

So to summarize:

"negligible difference, if equal other variables will take precedence"
- with assumed similar Vd cabs, one with higher Sd and the other higher Xmax, you experience similar SPL and similar weight & size for both. was cost similar as well?
- remaining and definitely non-negligible difference for this instance is tone... entirely subjective, and a matter of taste.

Curious if they actually are close to equal Vd. Don't suppose you have the relevant measurements available to see how close they are, and how much they differ in the other variables?

(Unlikely, I know. )

[Codger]

Originally Posted by dhsierra1

my explanation of compliance wasn't about T/S compliance, sorry for the confusion.

Not to put too fine a point on it, but there is at least one AES paper that discusses the frequency dependence of the materials used for loudspeaker suspensions. Its effects don't seem to appear in the usual models AFAIK. Unfortunately my membership has lapsed and I am stuck reading only the synopsis.

[dhsierra1]

Originally Posted by Codger

Not to put too fine a point on it, but there is at least one AES paper that discusses the frequency dependence of the materials used for loudspeaker suspensions. Its effects don't seem to appear in the usual models AFAIK. Unfortunately my membership has lapsed and I am stuck reading only the synopsis.

not surprising, many materials (and mechanical structures) have frequency dependent mechanical properties, didn't know that was looked at by the AES peeps, bet that's an interesting read

Sorry for the thread derail, folks, won't happen again

[KJung]

Originally Posted by makohund

So to summarize:

"negligible difference, if equal other variables will take precedence"
- with assumed similar Vd cabs, one with higher Sd and the other higher Xmax, you experience similar SPL and similar weight & size for both. was cost similar as well?
- remaining and definitely non-negligible difference for this instance is tone... entirely subjective, and a matter of taste.

Curious if they actually are close to equal Vd. Don't suppose you have the relevant measurements available to see how close they are, and how much they differ in the other variables?

(Unlikely, I know. )

Good summary. Again, the 'higher xmax' deeper voiced cab has similar max SPL, but it took more power to get there. Not surprising. Deeper lows, less baked in mid response equals less efficient (for the most part).

Cost was a bit less for the 210, but relatively close.

And yes, tone is the primary difference, which of course, for a musician, is the primary driver in choosing a cab, IF the performance (i.e., low end reproduction and max volume) is sufficient for the context and player's tone goals.

No, I don't have any exact measurements on the drivers. The 'high xmax' driver is an OEM 4ohm version of the 3012LF (big horn crossed over around 1K), revised to have a bit higher response frequency distribution to work a bit better in a smaller box. The 210 uses Jim Bergantino's OEM version of more standard Eminence neo bass speakers (not HO's or LF's... but not sure which models, with a more standard tweeter crossed over around 3K, from what I understand).

[will33]

Originally Posted by dhsierra1

not surprising, many materials (and mechanical structures) have frequency dependent mechanical properties, didn't know that was looked at by the AES peeps, bet that's an interesting read

Sorry for the thread derail, folks, won't happen again

You're over my head with that stuff.


Would I be correct in assuming the larger surface traveling less distance to achieve the same displacement would present less Doppler distortion effect?


Example: in subwoofers, you can send a direct radiator sub nothing but <100hz content and it's cone distortion will give you back some >100hz. Is that an effect of just the cone "slapping" or "shoving" the air, or some other cone behavior (ripples/not acting as a true piston or whatever)?

[makohund]

Originally Posted by barryaudio

IDK, comparing Thunderchild112 and a Bergantino AE210 is not the best comparison for this particular thought experiment. One uses an LF speaker and the other a pair of full range. They are also totally different designs up and down the frequency spectrum, so how can one compare the tone differences with regards to speaker size? That's like saying my '70 Fender Jazz sounds different than my Dingwall ABZ5, so 4 string and 5 string basses must sound different.

regarding off-axis: a 10" speaker will have a beaming limit of about 1.6kHz, so I would challenge that the TC would have better off-axis performance due to the tweeter bearing the load of upper mids and highs.

"maximum volume": I think you are actually referring to sensitivity? I would believe that the 210 would have a higher sensitivity anyway for a few reasons: (a) they use full range speakers which in general are more sensitive (b) 2x10 is 40% more surface area than 1x12 (c) even with the same size speaker, typically the tradeoff for higher xmax is lower sensitivity. Without knowing the xmax of the 10s in the Berg cab, it would be difficult to model "maximum volume".

I think it's actually a pretty good one, precisely because they are such completely different approaches to generating SPL, and illustrate the tradeoffs involved.

The 2x10 has the advantage of higher Sd. It has the advantage of higher sensitivity, for the reasons you give. If vertical(-ish), it has a slight advangage over a full range 12 in terms of beaming frequency.

Despite all of those advantages, the 2-way 12 is being reported as "just as loud". It's not a full range woofer, and it makes up for less "everything the 2x10 has over it" with that huge xmax. Which comes with it's own drawback... doesn't cover the whole range. This is made up for with the crossover & tweeter... which also puts it past the 2x10 in terms of dispersion/beaming. (Whether or not one hears, uses, or prefers the result, that horn is simply more capable up there than the fullrange 10.)

There is the matter of how loud, and at what frequencies the peaks are. That can all be measured. Interpreting the measurements can be interesting... where the curves (or lack of) do/don't tend to slot into mixes, where they lie along the typical human hearing sensitivity curve, how amenable they are to manipulation by EQ.

But that interpretation is also the start of drift into subjective territory.

What I take away from it, and all of the other posts (other than the already noted exception), is that it doesn't really matter much whether one gets their displacement (and SPL in the low end frequencies) primarily via lots of surface area, or primarily via high Xmax, or any ratio of the two in between. One method is not inherently "better" or more efficient than the other.

If there is a size or weight advantage to either in a given case, it is not in any way a compromise to prefer the one having those advantages. It might be odd to prefer the one without the advantage, unless there is an overriding subjective reason behind it.

The critical differences seem to be the same as they are for any other speaker comparison. In light of recent threads, I'll break my thinking into objective/subjective components.

1. Desired sound/tone capabilites. Sound/tone generation and makeup are objective, measurable and explainable. The particular "tones desired" are purely subjective, a matter of preference.

2. Producing it at the SPL needed. The levels (including frequency range and curve) differences are measurable and comparable. The levels needed for common scenarios are quantifiable to some extent. The "levels needed" by an individual is subjective.

3. Delivering it where you need/want it to go. Sound distribution from a source is objective, measurable and comparable. Where an individual actually wants or needs that sound to go is subjective.

4. Manifested in a object that is physically and situationally suited for one's needs. The objective/subjective components of that should be plain enough, I hope.


Ergo... simply choosing Sd over Xmax in any scenario, regardless of the other variables in play (both objective and subjective), would be pointless. Better to satisfy one's subjective preferences first. Objective qualities do not dictate preference, but are a fantastic tool for narrowing down the playing field to those worth the time and effort to experience first hand. (They can also make final cuts between candidates that have already passed all subjective tests.)

Am I crazy, or does that sound reasonable?

There is that one outlier... I still want to know more about the power transfer/air impedance thing craig.p was talking about.

[makohund]

Originally Posted by dhsierra1

not surprising, many materials (and mechanical structures) have frequency dependent mechanical properties, didn't know that was looked at by the AES peeps, bet that's an interesting read

Sorry for the thread derail, folks, won't happen again

No worries about derail... that is precisely the sort of educational or even esoteric details I'm interested in.

Originally Posted by will33

Would I be correct in assuming the larger surface traveling less distance to achieve the same displacement would present less Doppler distortion effect?


Example: in subwoofers, you can send a direct radiator sub nothing but <100hz content and it's cone distortion will give you back some >100hz. Is that an effect of just the cone "slapping" or "shoving" the air, or some other cone behavior (ripples/not acting as a true piston or whatever)?

I wanna know, too.