What to look for in a sub

[snodog]

Dont know too much about the technical aspect, what are some key features to look for? I am looking for a fairly small to medium room but eventually will add an additional sub. I am interested in the Ultra 10 for sure, does that look like a good buy for features vs price?
Also is there an advantage to sealed vs ported?

[ntrain42]

Jan 23, 2010 22:48:20 GMT -5 @snodog said:

Dont know too much about the technical aspect, what are some key features to look for? I am looking for a fairly small to medium room but eventually will add an additional sub. I am interested in the Ultra 10 for sure, does that look like a good buy for features vs price?
Also is there an advantage to sealed vs ported?

To make it short, the things I look for in a sub is a sealed DOWNFIRING design, with an EFFICIENT sub driver and a good flexible plate amp.

Keys:

A. Sealed design: Smoother and more linear bass response with a lower potential to clip/distort due to the sealed acoustic suspension.

B. Downfiring sub: When a sub is compression loaded directly into the floor it tends to flatten and extend the bass frequency lower

C. Efficiency: This is a big one. Just because a subwoofer has a big 1000watt class D amp, does not mean its going to play louder or sound better. Many of the subs on the market need big honkin amps just to move the driver due to the huge magnet structure and large voicecoil(which equates to a larger voicecoil gap)assembly. Do not be fooled by power ratings either as many times the power #'s are given at high distortion levels of 10% or greater.

D. Flexibility of the plate amp. A good subwoofer plate amp at the very least should have a VARIABLE 0-180 phase control and a VARIABLE xover control (40hz-80hz minimum). The better ones will have selectable slope( 12/24db) and even one or more bands of parametric EQ functions to eliminate room modes. The best sounding subs I have heard use a true Class A/B amps(Revel and Rythmik are 2 of them). Most sub plate amps though or the class D variety though due to cost of mfg. and size and efficiency(you can pack a larger Class D amp into a smaller space).

This should help get you started.

[DYohn]

I disagree about the benefits of a downfiring design. "Compression loaded" with the floor?

In my experience down-firing subwoofers can be more problematic in-room than front-firing in terms of activating room modes that must be dealt with using treatments. Coupling with the floor can lead to excessive boominess, and changing position in the room has less effect on correcting these issues. Floor bounce cannot be controlled with a downfiring design.

In my opinion, there is no benefit to down-firing VS any other driver position except for possibly aesthetics and physical protection for the driver if you have small children in the house.

Also, while sealed systems tend to be easier to integrate with a room due to their shallower roll-off and lower group delay characteristics, I prefer the sound of vented alignments. This is mostly a taste thing and each user will have their own preferences.

[ntrain42]

Jan 24, 2010 11:25:36 GMT -5 DYohn said:

I disagree about the benefits of a downfiring design. "Compression loaded" with the floor?

In my experience down-firing subwoofers can be more problematic in-room than front-firing in terms of activating room modes that must be dealt with using treatments. Coupling with the floor can lead to excessive boominess, and changing position in the room has less effect on correcting these issues. Floor bounce cannot be controlled with a downfiring design.

In my opinion, there is no benefit to down-firing VS any other driver position except for possibly aesthetics and physical protection for the driver if you have small children in the house.

Also, while sealed systems tend to be easier to integrate with a room due to their shallower roll-off and lower group delay characteristics, I prefer the sound of vented alignments. This is mostly a taste thing and each user will have their own preferences.

Boominess? Not at all, if your getting "boominess" then your gains are set too high, or your sub is located to close to a room corner or wall. Downfiring or boundary loading as it is also know as, allows you to turn down gains and increases and flattens out frequency response naturally. Lower gains also means less harmonic distortion. It also naturally DECREASES LOCALIZATION of higher frequencies it may be playing allowing your sub to blend in better with your main satalites and allows the unit to disappear.

Didnt they teach you this in THX certification school?

[DYohn]

Jan 24, 2010 12:20:24 GMT -5 ntrain42 said:

Didnt they teach you this in THX certification school?

If either of us needs to go back to school it's you.

[ntrain42]

Jan 24, 2010 12:22:16 GMT -5 DYohn said:

Jan 24, 2010 12:20:24 GMT -5 ntrain42 said:

Didnt they teach you this in THX certification school?

If either of us needs to go back to school it's you.

LOL, uhuh, try again homie............ your knowledge many times is seriously lacking on a number of subjects on the audio boards seriously. Your posts/rebuttals/debates always lack tangible information and never have any examples backed up with fundamental facts and common sense knowledge. ;D

[DYohn]

You bet.

[jlafrenz]

Jan 24, 2010 12:27:14 GMT -5 ntrain42 said:

Jan 24, 2010 12:22:16 GMT -5 DYohn said:

If either of us needs to go back to school it's you.

LOL, uhuh, try again homie............ your knowledge many times is seriously lacking on a number of subjects on the audio boards seriously. Your posts/rebuttals/debates always lack tangible information and never have any examples backed up with fundamental facts and common sense knowledge. ;D

It seems that most of your knowledge is based purely on opinion. Though you seem to think so, your opinions are not hard facts.

[mrmeng430]

Dear Subwoofer gurus,

Is the Epik Empire a good buy on paper?? www.epiksubwoofers.com/blog/?m=201001

[snodog]

What is bizarre to me is the fact that some subs are 150 watts and others are 1000. This is NOT a factor? It seems like it would be but again I dont know much about it. The only sub I've used is my Paradigm pdr-10 which is only an entry level so I am excited to know that I will be gaining quality in the bass dept. I would be willing to give the Emo sub a try when they are released, but would like to learn more about what to look for or listen for

[jlafrenz]

Jan 24, 2010 12:55:09 GMT -5 @snodog said:

What is bizarre to me is the fact that some subs are 150 watts and others are 1000. This is NOT a factor? It seems like it would be but again I dont know much about it. The only sub I've used is my Paradigm pdr-10 which is only an entry level so I am excited to know that I will be gaining quality in the bass dept. I would be willing to give the Emo sub a try when they are released, but would like to learn more about what to look for or listen for

Its all about design. Think of it this way with a car analogy. A muscle car has a has a huge engine and can go X miles per hour. A small tuner car can go that same speed with less HP based on the way the motor was built and the weight of the car. Same with subs. It is how it is designed and what it is trying to move.

[ntrain42]

Jan 24, 2010 12:45:00 GMT -5 jlafrenz said:

Jan 24, 2010 12:27:14 GMT -5 ntrain42 said:

LOL, uhuh, try again homie............ your knowledge many times is seriously lacking on a number of subjects on the audio boards seriously. Your posts/rebuttals/debates always lack tangible information and never have any examples backed up with fundamental facts and common sense knowledge. ;D

It seems that most of your knowledge is based purely on opinion. Though you seem to think so, your opinions are not hard facts.

Really then do some google searches on Boundary loading, sealed acoustic suspension, frequency localization effects, speaker voice coil design,magnet strength, voice coil gap, Bl, Q, VAS, etc etc etc.........lots of hard facts will probably rear their head........again, why not discount what I say with some hard core facts posted on your own? You and a few select others, make a point to try and bash what I say, but you never post the hard facts or links of your own from your own "opinion" and standpoint. Why is that? Why not make an educational post showing your own stance and school of thought? Id love to see em.

[ntrain42]

Jan 24, 2010 12:55:09 GMT -5 @snodog said:

What is bizarre to me is the fact that some subs are 150 watts and others are 1000. This is NOT a factor? It seems like it would be but again I dont know much about it. The only sub I've used is my Paradigm pdr-10 which is only an entry level so I am excited to know that I will be gaining quality in the bass dept. I would be willing to give the Emo sub a try when they are released, but would like to learn more about what to look for or listen for

Again power ratings is not a garentee on total SPL output abilities. Many subs will have large inefficient magnet structures with multi layered voice coils that require a large coil gap. Larger gaps tend to me more inefficient and require more power to get the same output as a more efficient sub with a smaller motor structure with a smaller coil gap. The enclosure itself plays a role as well, along with the size of the surface area of the driver, the linear excursion max etc etc.........alot of factors play into the design.

[ntrain42]

Jan 24, 2010 13:00:16 GMT -5 jlafrenz said:

Jan 24, 2010 12:55:09 GMT -5 @snodog said:

What is bizarre to me is the fact that some subs are 150 watts and others are 1000. This is NOT a factor? It seems like it would be but again I dont know much about it. The only sub I've used is my Paradigm pdr-10 which is only an entry level so I am excited to know that I will be gaining quality in the bass dept. I would be willing to give the Emo sub a try when they are released, but would like to learn more about what to look for or listen for

Its all about design. Think of it this way with a car analogy. A muscle car has a has a huge engine and can go X miles per hour. A small tuner car can go that same speed with less HP based on the way the motor was built and the weight of the car. Same with subs. It is how it is designed and what it is trying to move.

Oh really? So my point at letter "C" must be true then.........so now your contradicting what you said about my knowledge in essense...............by stating what you just did with your analogy of a musclecar your basically agreeing with point C I made............yet what did you say in the previous post about me?

[jlafrenz]

Jan 24, 2010 13:04:10 GMT -5 ntrain42 said:

Jan 24, 2010 12:45:00 GMT -5 jlafrenz said:

It seems that most of your knowledge is based purely on opinion. Though you seem to think so, your opinions are not hard facts.

Really then do some google searches on Boundary loading, sealed acoustic suspension, frequency localization effects, speaker voice coil design,magnet strength, voice coil gap, Bl, Q, VAS, etc etc etc.........lots of hard facts will probably rear their head........again, why not discount what I say with some hard core facts posted on your own? You and a few select others, make a point to try and bash what I say, but you never post the hard facts or links of your own from your own "opinion" and standpoint. Why is that? Why not make an educational post showing your own stance and school of thought? Id love to see em.

Sorry to Snodogg for taking this off track.

ntrain... so you have proven you can use google. Congrats. Many times people don't go in depth with you because it comes to a point of arguing just to argue with you. It is pointless and contributes nothing to the thread.

I do have a question for you though. You don't own any Emotiva gear and don't seem to have any interest in owning any. So why in the hell are you even on this forum?

Now back to your regularly scheduled programming

[DYohn]

Jan 24, 2010 12:55:09 GMT -5 @snodog said:

What is bizarre to me is the fact that some subs are 150 watts and others are 1000. This is NOT a factor? It seems like it would be but again I dont know much about it. The only sub I've used is my Paradigm pdr-10 which is only an entry level so I am excited to know that I will be gaining quality in the bass dept. I would be willing to give the Emo sub a try when they are released, but would like to learn more about what to look for or listen for

Sure, raw power is a factor. But be aware that the theoretical dbSPL increase with the same loudspeaker going to 1000 watts from 100 watts is +10db, or twice as loud. Overall system efficiency is the key reason for using larger power amplifiers, not necessarily loudness.

Here's something I wrote several years ago for a car audio publication that you might find useful:

People often try to calculate predicted SPL values based on the "db/watt-meter" ratings given for their loudspeakers. This is not strictly correct, and in fact may be way off.

The sensitivity of a loudspeaker is the medium sound pressure between 125 Hz to 4 kHz using a constant voltage at a specific distance; measured in dB per watt and meter. Usually 2.83 volts is used as this corresponds to 1 watt @ 8 ohms, with the SPL measured at 1 meter.

For instance the sensitivity of an 8-ohm loudspeaker might be listed as 92 dB / 2.83 volts / 1 meter. In this case the power (P = V squared / R) = 2.83 X 2.83 / 8 = 1 watt. In a 4-ohm loudspeaker 2.83 volts will generate 2 watts. To get the actual reference value at 1 watt, you have to subtract 3 dB (power cut in half) from the sensitivity measured; if the speaker was measured at 2-ohms, you subtract 6db, etc. Many car audio manufacturers fail to include this correction. Some cheat it by measuring at 0.5 meter. Some intentionally fudge the numbers or the test voltage. Also since the value is measured at frequencies higher than normal subwoofer usage bands, it may or may not be 100% accurate below 80Hz. Good manufacturers will do it right and give you accurate numbers, and often will include specifics about the test such as if a subwoofer was measured using standard frequency sweeps or using sub-woofer sweeps below 80Hz.

But there are other factors contributing to the overall system efficiency and resulting output levels in a car. The speaker enclosure adds several SPL components, especially using a ported system. The vehicle has what’s called “cabin gain,” or the many resonances set up as the closed vehicle functions as a resonance chamber similar to what happens inside a loudspeaker enclosure. These items might increase the system sensitivity value by as much as 6db or even more, and increase the overall system efficiency from the lowly speaker averages of 1 or 2% to 50 or 60% or more.

So a simple calculation beginning with the speaker’s sensitivity rating and working up by adding 3db for every doubling of input power will only tell you part of the story. (BTW, the raw SPL difference between 1 watt and 1000 watts is +30db.) It only indicates what the speaker would do in a free air anechoic test chamber at 1 meter away. A better method is to test the system after installation and determine the overall system sensitivity. Then a calculation to determine required wattage to achieve a particular db SPL value will have much more meaning. Also realize that SPL decreases with distance at a rate of -6db for each doubling of distance. So if the output is 87 db at one meter, at 2 meters the output will be 81 db. It is critical to know where the test mic will be positioned in relation to the speakers to calculate a predicted output level.

By the way, system efficiency ("n0" or eta naught) is a measure of how much incoming electrical energy is converted into acoustic energy. Often loudspeaker manufacturers will not give you this value, but for good quality loudspeakers a typical value might be between 0.2 % and 2 % and means that only 2% of the amplifier signal is actually being converted into sound, the rest is being wasted as heat. Some high efficiency subwoofers might get as high as 10% or 15%, but high efficiency speakers like compression drivers designed for pro audio can be almost 100% efficient (100% efficiency is 112db/watt-meter.) You can convert the listed sensitivity number into an efficiency using this formula: Efficiency = 10^(Sensitivity in dB - 112)/10.

[jlafrenz]

Jan 24, 2010 13:10:13 GMT -5 ntrain42 said:

Jan 24, 2010 13:00:16 GMT -5 jlafrenz said:

Its all about design. Think of it this way with a car analogy. A muscle car has a has a huge engine and can go X miles per hour. A small tuner car can go that same speed with less HP based on the way the motor was built and the weight of the car. Same with subs. It is how it is designed and what it is trying to move.

Oh really? So my point at letter "C" must be true then.........so now your contradicting what you said about my knowledge in essense...............by stating what you just did with your analogy of a musclecar your basically agreeing with point C I made............yet what did you say in the previous post about me?

What I said was MOST, not necessarily all. I never said everything you stated was wrong or that I never agree with you. I stated that you often think your opinion is hard fact. It seems you may have taken what I said slightly out of context. Also please keep in mind that my statement was a general observation about all your posts here on the forum, not necessarily this particular subject.

P.S. I am still waiting for an answer to my question I had from you.

[ntrain42]

Jan 24, 2010 13:11:50 GMT -5 jlafrenz said:

Jan 24, 2010 13:04:10 GMT -5 ntrain42 said:

Really then do some google searches on Boundary loading, sealed acoustic suspension, frequency localization effects, speaker voice coil design,magnet strength, voice coil gap, Bl, Q, VAS, etc etc etc.........lots of hard facts will probably rear their head........again, why not discount what I say with some hard core facts posted on your own? You and a few select others, make a point to try and bash what I say, but you never post the hard facts or links of your own from your own "opinion" and standpoint. Why is that? Why not make an educational post showing your own stance and school of thought? Id love to see em.

Sorry to Snodogg for taking this off track.

ntrain... so you have proven you can use google. Congrats. Many times people don't go in depth with you because it comes to a point of arguing just to argue with you. It is pointless and contributes nothing to the thread.

I do have a question for you though. You don't own any Emotiva gear and don't seem to have any interest in owning any. So why in the hell are you even on this forum?

Now back to your regularly scheduled programming

Actually most people don't argue on points of merits because they have none to give. Your the perfect example so far to date. Again, you just posted another worthless post in essense.

[ntrain42]

Jan 24, 2010 13:29:15 GMT -5 jlafrenz said:

P.S. I am still waiting for an answer to my question I had from you.

And what question was that?

[Wideawake]

Jan 24, 2010 13:21:33 GMT -5 DYohn said:

Sure, raw power is a factor. But be aware that the theoretical dbSPL increase with the same loudspeaker going to 1000 watts from 100 watts is +10db, or twice as loud. Overall system efficiency is the key reason for using larger power amplifiers, not necessarily loudness.

Here's something I wrote several years ago for a car audio publication that you might find useful:

People often try to calculate predicted SPL values based on the "db/watt-meter" ratings given for their loudspeakers. This is not strictly correct, and in fact may be way off.

The sensitivity of a loudspeaker is the medium sound pressure between 125 Hz to 4 kHz using a constant voltage at a specific distance; measured in dB per watt and meter. Usually 2.83 volts is used as this corresponds to 1 watt @ 8 ohms, with the SPL measured at 1 meter.

For instance the sensitivity of an 8-ohm loudspeaker might be listed as 92 dB / 2.83 volts / 1 meter. In this case the power (P = V squared / R) = 2.83 X 2.83 / 8 = 1 watt. In a 4-ohm loudspeaker 2.83 volts will generate 2 watts. To get the actual reference value at 1 watt, you have to subtract 3 dB (power cut in half) from the sensitivity measured; if the speaker was measured at 2-ohms, you subtract 6db, etc. Many car audio manufacturers fail to include this correction. Some cheat it by measuring at 0.5 meter. Some intentionally fudge the numbers or the test voltage. Also since the value is measured at frequencies higher than normal subwoofer usage bands, it may or may not be 100% accurate below 80Hz. Good manufacturers will do it right and give you accurate numbers, and often will include specifics about the test such as if a subwoofer was measured using standard frequency sweeps or using sub-woofer sweeps below 80Hz.

But there are other factors contributing to the overall system efficiency and resulting output levels in a car. The speaker enclosure adds several SPL components, especially using a ported system. The vehicle has what’s called “cabin gain,” or the many resonances set up as the closed vehicle functions as a resonance chamber similar to what happens inside a loudspeaker enclosure. These items might increase the system sensitivity value by as much as 6db or even more, and increase the overall system efficiency from the lowly speaker averages of 1 or 2% to 50 or 60% or more.

So a simple calculation beginning with the speaker’s sensitivity rating and working up by adding 3db for every doubling of input power will only tell you part of the story. (BTW, the raw SPL difference between 1 watt and 1000 watts is +30db.) It only indicates what the speaker would do in a free air anechoic test chamber at 1 meter away. A better method is to test the system after installation and determine the overall system sensitivity. Then a calculation to determine required wattage to achieve a particular db SPL value will have much more meaning. Also realize that SPL decreases with distance at a rate of -6db for each doubling of distance. So if the output is 87 db at one meter, at 2 meters the output will be 81 db. It is critical to know where the test mic will be positioned in relation to the speakers to calculate a predicted output level.

By the way, system efficiency ("n0" or eta naught) is a measure of how much incoming electrical energy is converted into acoustic energy. Often loudspeaker manufacturers will not give you this value, but for good quality loudspeakers a typical value might be between 0.2 % and 2 % and means that only 2% of the amplifier signal is actually being converted into sound, the rest is being wasted as heat. Some high efficiency subwoofers might get as high as 10% or 15%, but high efficiency speakers like compression drivers designed for pro audio can be almost 100% efficient (100% efficiency is 112db/watt-meter.) You can convert the listed sensitivity number into an efficiency using this formula: Efficiency = 10^(Sensitivity in dB - 112)/10.

Very nice! Learned a bit and clarified some things for me. Do you have other articles that you can share with us? Or, please pm me if you don't want to post them on the Emo boards.