ok stereo guys

[89GMCSuburban]

My fosgate was box rated at 700 watts, but the bench test slip that all fosgates had showed mine bench rated at 846 watts.

 

[chevyin]

Again, cone size has virtually nothing to do with how 'muddy' or 'slow' the speaker will react. Read the link I provided, it explains it in thorough detail. For example, I bet you didn't realize many home pro audio systems utilize 15-18" midrange drivers, did you?

If you guys want to discuss what really changes transient response of a sub system, you should be focusing on the enclosure type/size/alignment, and how the motor reacts to the amount of current passing through it. If you want to discuss the performance of a sub's transient response based on the cone size, you are barking up the wrong tree totally.

 

[fortcollinsram]

I have had sealed, bandpass and ported boxes. I like the musicality of the seal box the most but I like the bump of the ported box. I have 2 ImageDynamics IDQ12's in a sealed box with 300watts each I I LOVE this setup. It hits plenty hard and sounds SOO clean...

 

[Greg72]

Again, cone size has virtually nothing to do with how 'muddy' or 'slow' the speaker will react. Read the link I provided, it explains it in thorough detail. For example, I bet you didn't realize many home pro audio systems utilize 15-18" midrange drivers, did you?

If you guys want to discuss what really changes transient response of a sub system, you should be focusing on the enclosure type/size/alignment, and how the motor reacts to the amount of current passing through it. If you want to discuss the performance of a sub's transient response based on the cone size, you are barking up the wrong tree totally.

That Adire site seems to be drawing some dubious conclusions about inductance vs. mass???

The article started out fine, with a little bit of f=ma....which I think we can all relate to....then a little information about the magnetics of a speaker and how motion is created.

What I am failing to see is:

Source Signal - Where is the reference signal that the speaker was given to reproduce? It's hard to appreciate the "accuracy" or "transient response" of a speaker when you can't see how faithfully it reproduces the original signal.

Mass - Adding 28grams (less than 1 ounce) of mass to a speaker cone hardly proves that mass is an irrelevant factor. Double the weight of the cone (for example) and re-test... Even with only a small added weight the speaker (this is the blue line in the graph, as far as I can tell) did not seem to track very impressively to the other response pulses.


I can appreciate that overcoming a high voice coil inductance may be a real issue, but the article seems to state (unfairly) that mass is not a consideration...


I guess the closest analogy I can muster is:

Low Inductance = Crisp Throttle Response
Cone Mass = Vehicle Weight

It's nice to have the crisp throtle response, but ultimately it still has to move whatever weight the car has.... and it will still struggle against that mass until it gets it moving.


The analogy may not be perfect, but in either case...more power is a good thing. A lazy-sounding speaker can really come alive with a healthy dose of power....just as a 6000Lb Blazer could conceivably run a 12-second 1/4 mile with enough motor!!!!

 

[chevyin]

That Adire site seems to be drawing some dubious conclusions about inductance vs. mass???

That tech article was written by Dan Wiggins of Adire Audio, considered one of the leaders in speaker design today (was the main force in develpoing the new motor topology called xbl^2). Just to give you some background on the author.

Source Signal - Where is the reference signal that the speaker was given to reproduce? It's hard to appreciate the "accuracy" or "transient response" of a speaker when you can't see how faithfully it reproduces the original signal.

Comparing the test data to the signal material would prove nothing in this test, which I assume is why Dan left it out. These tests are to compare the speaker when 1) mass is added, and 2) when the inductance of the coil is changed. The comparison that needed to be done was the speaker with those two criteria compared to the speaker with no mass or inductance added. In other words, the test was simply to see the effects of adding weight and/or inductance, then compare it to the original speaker's response to find out which actually affects transient response. This is what Dan did, and his results showed inductance was in fact the cause of variation in transient response, rather than mass. The test speaker could have been a top quality unit that reproduced the original source material faithfully, or it could have been a cheap WalMart speaker whose response was sloppy. It doesn't matter, that's not the point of the article, its to see how changing two specific specs will affects the speaker's performance (in relation to no changes added).

Mass - Adding 28grams (less than 1 ounce) of mass to a speaker cone hardly proves that mass is an irrelevant factor. Double the weight of the cone (for example) and re-test... Even with only a small added weight the speaker (this is the blue line in the graph, as far as I can tell) did not seem to track very impressively to the other response pulses.

You must have missed the part where he said he did in fact double the moving mass of the speaker: "Added mass was 28.5 grams (Mms of the Extremis 6-8 is 24.39 grams per Kilppel)"

The graphs do in fact show the discrepancy Dan is talking about, but yes they are a bit confusing, let me try to explain. First off, to really see the variation in transient response, look at the bottom graph on the article (frequency response). Above 4khz its plain to see the green line (inductance added) is not keeping up with the red and blue lines (raw and mass-added responses). Below that the mass added line dips lower, but this is explained by the changed in Mms that occurred by adding the mass, which actually shifts the response curve a bit lower. The dips at the low end of the spectrum are based on lower frequency response, not transient reponse (Dan mentions that somewhere in the article iirc). It was probably at the lower end of the freq spectrum that you were tracking the blue line and felt it did not track well. Remember also, the higher the frequency, the faster the response time must be (tweeter needs more than mids which need more than subs etc). Therefore its at the top end of the freq spectrum that these discrepancies will be most obvious, which that graph shows.

I can appreciate that overcoming a high voice coil inductance may be a real issue, but the article seems to state (unfairly) that mass is not a consideration...

Why do you say unfairly? The point of that tech article is to prove exactly that, that mass really isn't a factor, inductance is. If Dan had simply written a paragraph stating this opinion, Id agree it was unfair. But, he took the time to show the equations and explain the logic, step by step. I certainly wouldn't call it unfair, Id call it proven. *shrug*

I guess the closest analogy I can muster is:

Low Inductance = Crisp Throttle Response
Cone Mass = Vehicle Weight

It's nice to have the crisp throtle response, but ultimately it still has to move whatever weight the car has.... and it will still struggle against that mass until it gets it moving.


The analogy may not be perfect, but in either case...more power is a good thing. A lazy-sounding speaker can really come alive with a healthy dose of power....just as a 6000Lb Blazer could conceivably run a 12-second 1/4 mile with enough motor!!!!

More power is not always a good thing, not in speaker motors. There is such a thing as 'overmotored', a sub that produces more BL force than is necessary, thereby hurting it in other areas (T/S specs are all about compromises between each of them... raise one thing excessively and another spec will be ill-affected). Designing a sub is like walking a tight-rope. For example, you can have 2 of the 3 following: small enclosure size, efficiency, and low end response.... but you cannot have all three. Add massive amounts of BL force (motor force) and the driver's Qes will suffer, which will make low end response suffer (but midbass will be like its on steroids). Speaker design is a give and take, unlike your analogy of a motor in truck where more power is almost always beneficial, in a speaker, this is not always the case.

I guess Im not sure what to say here toher than try reading the article again, maybe do some independant research on the subject when you get a chance. Dan lays it all out in black and white, the equations, the explanations, etc. I will also add that this has become a well accepted 'theory' of how mass and inductance affect woofer performance. I have witnessed representatives from other companies (including Kicker, JL Audio and a few others) refer to Dan's article as fact.

Take an example I have: Pick up two small pebbles off the ground and place one in each hand. Now shake your fists back and forth as vigorously as possible. Could you feel a difference in each hand's motion based on the small amount of mass difference between the two pebbles? No, you couldn't (unless you picked up large rocks ). This is similar to the effect of mass on the speaker's motion. The amount of force involved here (generally in the 2-4hp range for most modern subs) greatly overshadows the few gram difference you would experience going from one size to another within a speaker model. But, what would affect your fists' "transient response" would be the amount of energy you put into shaking your hands back and forth (this would be the inductance in a speaker's motor, the moving force).

Does adding mass to a speaker affect its performance? Yes, of course it does. Adire's tech article is certainly not suggesting there is no change in performance based on mass (that would be absurd). Mass affects the Mms of the driver (or should I say IS the Mms), which affects its frequency response (how low or high it will extend). But, it does not affect the transient response of a driver, at least not in the way most people tend to think.

Hope that helps explain it a bit better.

 

[shaun89]

ported boxes hit harder (best for rap) but enclosed boxes have a smoother sound to them (best for rock), if u have a ported box and have continuous bass, it starts to sound wavy as the air escapes the ports. enclosed boxes dont have that wavy sound to them.

 

[MrArmyAnt]

Ported = harder, louder, harder to tune, innacurate. Enclose (sealed) = most accurate, easiest to build, not loudest.

 

[chevyin]

Ported = harder, louder, harder to tune, innacurate. Enclose (sealed) = most accurate, easiest to build, not loudest.

Most people would call infinite baffle the most accurate, when done correctly, as it offers no coloration due to enclosure alignment. And low tuned ported boxes can sound very very good. But in general yes most sealed systems offer superior sound quality to most vented systems. Vented systems have group delay issues that sealed systems do not, if nothing else.

 

[Blue85]

Which is better depends a lot on the sub (the Q, the Xmax, etc.) I never build sealed boxes because you need expensive subs and big power to get any decent low-end response (If you do, it can be super-tight, though). Bandpass is tricky to tune correctly, so I will have to vote for vented (ported).

I like to use WinISD, which is free. It saves you from all the calculator punching and works well whether you want to use an existing (purchased) box or design your own. You just set the tuning frequency you want, box size, etc. and it calculates port length, diameter, etc. Running a quick design with all three box types (bandpass, sealed, vented) lets you see quickly which ones work well with the speakers you have.

You will need to find the speaker parameters on the manufacturer's website no matter method you use for design.

 

[chevyin]

Sealed systems actually have the best low frequency extension over ported, generally speaking. The actual low-end response and efficiency will be highly dictated by the enclosure's alignment (size). Usually people who say ported systems have better low end are referring the the exagerrated boost the port gives around its tuning frequency. In other words, vented systems have more output in the low end, but do not extend as low as a sealed system. Sealed systems do not have to be concerned about the speaker unloading below tuning. Sealed systems can play anything down to 1hz without concern, ported systems will not allow much deviation below their tuning frequency. More, not lower.

Yes, certain subs lend themselves to vented or sealed systems. My comments have been geared towards general comparisons between the enclosure types alone, ignoring any situation where a driver performs better in one type or the other.

WinISD is a nice little program, I use it myself. Just remember, its response graphs are not an in-car response curve.