got bored, wanted to give back, wrote a paper. here is an excerpt:

QUANTITATIVE ANALYSIS OF CRAIGSUB HT SUBWOOFER RATINGS

Publius

\tIn a novel dataset, the craigsub HT subwoofer scores, a small number of readily acquired variables explain the overwhelming majority of variation in home theater subwoofer performance, upwards of 95%. Therefore, quantitative methods may be tremendously valuable in assisting the subwoofer purchaser to sort through all the marketing hoopla that is all too common in the industry. Purchasers should focus on driver diameter, box volume, amplifier power, vented design, extreme linear excursion and possibly number of drivers. All these factors predict higher performance in home theater.

Reason for Inquiry

The craigsub data provide a great start to comparing many popular subwoofers. His stated goal,

The purpose of this information is to help people to quickly look at a variety of subwoofers and get a pair of scores, some performance numbers, and some listening tests describing the characteristics of each subwoofer. Hopefully, this will provide some assistance when researching for a subwoofer purchase.

Obviously, he has achieved his stated goal, but can we learn more? Is there anything that we can generalize from the data that will provide assistance to researching subwoofers that have not been tested. The subwoofer market is huge and highly fragmented. No reviewer can be expected to test them all and subjective scorings vary too much between reviewers (and their listening environments) to provide a sound basis for comparison. Illka subwoofer tests listed on hometheatershack.com are among the growing trend toward objective performance measurement, but such tests tell us nothing about how to generalize subwoofer principals in order to make predictions about subwoofers that have not been tested. This is the first such quantitative analysis of subjective subwoofer data of which the author is aware.

Data

craigsub subwoofer scoring data were gathered from avsforum.com, as of Feb 21, 2008. Manufacturer websites were used for subwoofer specifications where possible. If the model was an old model and no longer on the manufacturers website, a review website that reported specifications was used.

Methods

Multiple linear regression (MLS) methods have been used in a wide variety of fields to tease out relationships that may not be obvious using other quantitative methods. Essentially, MLS is a tried and true method for identifying linear relationships between a dependent variable (subwoofer scores) and a set of independent or explanatory variables (driver diameter, amplifier power, etc.). By transforming data (taking roots, logs, etc.), non-linear relationships in data can also be identified. Dummy variables can be used to determine if binomial variables (such as vented/sealed) are significant.

Variables

craigsub home theater scores (HT) was the independent variable. The variables used to explain the HT score were:

VNT = dummy variable for whether the subwoofer is vented or passive radiator (this variable takes a one for vented or passive radiator, a zero for sealed enclosure).

DRVRS = number of drivers

DRV_DIAM = reported driver diameter (this is typically the diameter of the frame; the actual radiating portion is much smaller)

DxD2 = this is a compound variable that combines the number of drivers and the square of the driver diameter. This variable is a measure of the area of all the drivers.

PWR = reported RMS power of the amplifier.

BOX_VOL = volume of the enclosure. This is often not reported and so has to be estimated. Box volume is roughly the exterior volume, less wall thickness, less volume of amp and subwoofer driver, less internal bracing.

HI_XMAX = extreme xmax capability. This applies to drivers with linear excursion in the +/-35mm range. Dummy variable takes one for extreme excursion subs, zero otherwise.

COI = craigsub conflict of interest variable. Suspicions have been raised about the objectivity of the analysis, as craigsub and the principals at AV123 are known to be good friends and may have business dealings in development. This is another dummy variable that takes on a one for products from AV123.

QUANTITATIVE ANALYSIS OF CRAIGSUB HT SUBWOOFER RATINGS

Publius

\tIn a novel dataset, the craigsub HT subwoofer scores, a small number of readily acquired variables explain the overwhelming majority of variation in home theater subwoofer performance, upwards of 95%. Therefore, quantitative methods may be tremendously valuable in assisting the subwoofer purchaser to sort through all the marketing hoopla that is all too common in the industry. Purchasers should focus on driver diameter, box volume, amplifier power, vented design, extreme linear excursion and possibly number of drivers. All these factors predict higher performance in home theater.

Reason for Inquiry

The craigsub data provide a great start to comparing many popular subwoofers. His stated goal,

The purpose of this information is to help people to quickly look at a variety of subwoofers and get a pair of scores, some performance numbers, and some listening tests describing the characteristics of each subwoofer. Hopefully, this will provide some assistance when researching for a subwoofer purchase.

Obviously, he has achieved his stated goal, but can we learn more? Is there anything that we can generalize from the data that will provide assistance to researching subwoofers that have not been tested. The subwoofer market is huge and highly fragmented. No reviewer can be expected to test them all and subjective scorings vary too much between reviewers (and their listening environments) to provide a sound basis for comparison. Illka subwoofer tests listed on hometheatershack.com are among the growing trend toward objective performance measurement, but such tests tell us nothing about how to generalize subwoofer principals in order to make predictions about subwoofers that have not been tested. This is the first such quantitative analysis of subjective subwoofer data of which the author is aware.

Data

craigsub subwoofer scoring data were gathered from avsforum.com, as of Feb 21, 2008. Manufacturer websites were used for subwoofer specifications where possible. If the model was an old model and no longer on the manufacturers website, a review website that reported specifications was used.

Methods

Multiple linear regression (MLS) methods have been used in a wide variety of fields to tease out relationships that may not be obvious using other quantitative methods. Essentially, MLS is a tried and true method for identifying linear relationships between a dependent variable (subwoofer scores) and a set of independent or explanatory variables (driver diameter, amplifier power, etc.). By transforming data (taking roots, logs, etc.), non-linear relationships in data can also be identified. Dummy variables can be used to determine if binomial variables (such as vented/sealed) are significant.

Variables

craigsub home theater scores (HT) was the independent variable. The variables used to explain the HT score were:

VNT = dummy variable for whether the subwoofer is vented or passive radiator (this variable takes a one for vented or passive radiator, a zero for sealed enclosure).

DRVRS = number of drivers

DRV_DIAM = reported driver diameter (this is typically the diameter of the frame; the actual radiating portion is much smaller)

DxD2 = this is a compound variable that combines the number of drivers and the square of the driver diameter. This variable is a measure of the area of all the drivers.

PWR = reported RMS power of the amplifier.

BOX_VOL = volume of the enclosure. This is often not reported and so has to be estimated. Box volume is roughly the exterior volume, less wall thickness, less volume of amp and subwoofer driver, less internal bracing.

HI_XMAX = extreme xmax capability. This applies to drivers with linear excursion in the +/-35mm range. Dummy variable takes one for extreme excursion subs, zero otherwise.

COI = craigsub conflict of interest variable. Suspicions have been raised about the objectivity of the analysis, as craigsub and the principals at AV123 are known to be good friends and may have business dealings in development. This is another dummy variable that takes on a one for products from AV123.

Quantitative Analysis Subwoofers Revised.pdf 157.0439453125k . file

source_data.txt 2.8466796875k . file