The King of Bass is Dead, Long Live the New King

[toddalin]

Well guys, the results are in. Comparable testing of the W15GTI vs a 2205 recently remagnetized and reconed (in Dec 2005) as a 2235 show the W15GTI the clear and present winner in the reproduction of bass. Furthermore, the W15GTI has a more extended high end.

Both speakers are in the same enclosures and there is no reason that the results wouldn't be directly comparable.

It is also interesting to note that the W15GTI has a nice "hump" at 60 Hz whereas at that point the 2235 is starting to loose ground. From my experience with WinISD, I recognize that with the W15GTI, this hump could easily be smoothed out by further lowering the tuning of the cabinet which would further help the W15GTI go lower, and flatter.

Sorry that the format is a little hard to read. It's the fault of the web site tha twill not let me space the values, even though I've added blanks between them. If anyone would like to see the data, I have it in an excel sheet.

Frequency W15GTI 2235 Difference
Hz dBL dBL dBL

1500 91.9 84.5 7.4
1450 93.7 78.9 14.8
1400 95.6 87.9 7.7
1300 96.4 89.2 7.2
1200 98.8 90.5 8.3
1100 97.9 94.2 3.7
1000 92.3 101.4 -9.1
950 93.1 101.8 -8.7
900 95.3 101.9 -6.5
850 98.1 99.0 -0.9
800 103.0 98.3 4.7
750 101.2 98.7 2.5
700 100.0 96.6 3.4
650 99.1 98.2 0.9
600 98.7 99.1 -0.4
550 98.1 100.8 -2.7
500 98.8 100.1 -1.3
450 98.8 99.3 -0.5
400 97.9 99.6 -1.7
350 99.0 98.9 0.1
300 99.2 99.8 -0.6
250 100.2 100.0 0.2
200 100.0 100.0 0.0
180 100.0 100.0 0.0
160 99.8 100.5 -0.7
140 99.5 100.3 -0.9
120 101.5 101.4 0.1
100 101.3 100.7 0.6
90 101.6 101.8 -0.3
80 102.3 101.5 0.8
70 103.1 101.6 1.5
60 104.3 100.9 3.4
50 103.8 99.5 4.3
45 101.0 96.9 4.1
40 98.0 90.4 7.6
35 97.0 89.7 7.3
30 96.4 89.6 6.8
25 95.4 90.4 5.0
20 93.4 89.3 4.0

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/center-2235-w15gti.jpg

[Earl K]

Hi

- Interesting ! Nice to see these comparisons being posted .

May I suggest that you ;

- Post the Excel spreadsheet as a ( zipped ) attachment .
- This way someone can take that info and inturn display a viewable chart ( using Excels' builtin charting capabilities ) . I know a couple of folks around here, who are proficient at that ( including displaying in a logarithmic format ) .


:)

[Titanium Dome]

I'm sure others will chime in with technical questions to validate your results, but I'm just going to state that this is no surprise to me. That's one p-fine driver. :yes:

[toddalin]

Hi

- Interesting ! Nice to see these comparisons being posted .

May I suggest that you ;

- Post the Excel spreadsheet as a ( zipped ) attachment .
- This way someone can take that info and inturn display a viewable chart ( using Excels' builtin charting capabilities ) . I know a couple of folks around here, who are proficient at that ( including displaying in a logarithmic format ) .


:)

Anyone who wants the spreadsheets with the raw data is welcome to them. Just e-mail me at [email protected].

[edgewound]

Maybe you could keep us posted, Todd, on how they continue to behave over time. Your 2205/2235 is fairly new...how many listening hours do you think you have on them? The 2235 might wake up a little more down low with more break in. Just a thought.

[boputnam]

- Post the Excel spreadsheet as a ( zipped ) attachment . :yes:

[boputnam]

The 2235 might wake up a little more down low with more break in. Just a thought.My 2245's sure did - far, FAR beyond my expectations.

[boputnam]

Simple chart of the results...

[Earl K]

:thmbsup: :cheers: :applaud:

Cool Bo!

- You are definately my hero ( at least for the next few hours ).

:p

[boputnam]

- You are definately my hero ( at least for the next few hours ).Nice! I'll take it!

I love data analysis - although this ain't much to work with. I actually prefer the scatter plot - although it doesn't quantify the difference in response, it shows overwhelmingly that the results - as measured - favor the W15GTI.

[Earl K]

ummmmm,

- You may need to walk us mere mortals through the basics of scatter plots . :D

- Also, triangles vs squares ( or circles ) might be more demonstrative ( along with which is which ) . :)

;)

[Mr. Widget]

I love data analysis - although this ain't much to work with. I actually prefer the scatter plot - although it doesn't quantify the difference in response, it shows overwhelmingly that the results - as measured - favor the W15GTI.Please don't take this the wrong way, but I have a real problem with this thread's premise... Here we are comparing a subwoofer to a remarkably well balanced woofer. Other than seeing "as measured" that the subwoofer does indeed have greater output we really don't know anything about the relative quality of the two drivers in question. You probably could get a cheapo no-name sub from Parts Express and have similar results... that doesn't mean that it is a better woofer.

That said, I wouldn't be at all surprised if the W15GTI is a better subwoofer... the point is that the 2235 isn't a subwoofer. It is a woofer that is so capable that JBL found it acceptable to use it all the way up to 1000Hz in one application and use it as a sub in another... very few drivers are that capable.

Widget

[boputnam]

- Also, triangles vs squares ( or circles ) might be more demonstrative ( along with which is who / like a legend ) . :) I'm with Widget on this one...

But, to your question - the scatter plot are the paired data, by frequency.

For example:

for 1450 Hz, X = 93.7 and Y = 78.9, thus the point will plot below the Y = X line, biased toward the W15GTI

[boputnam]

- You may need to walk us mere mortals through the basics of scatter plots . :D One of the best uses of a scatter plot is for comparing agreement (correlation) between two data sets.

Here, we have data from two woofers. Plotting the pairs for each frequency gives the scatter plot. If the paired data were to cluster exactly along the Y = X line, then the data are highly correlated (R^2 = 1.0). Anything less than R^2 = 1.0 evidences less correlation.

These data - as measured - DO NOT cluster about the Y = X line, therefore are very dissimilar (FWIW, the R^2 = 0.32), and are strongly biased (cluster) toward the X axis.

Mind you, this analysis says nothing about the quality of the data - it merely analyzes the data, as is. Data integrity and validity is a whole 'nother discussion. I for one, would like to know more about how the data were collected... :)

[Titanium Dome]

In the car audio world, "woofers" are almost nonexistent. The nomenclature almost excludes them by definition. If you peruse JBL's car audio pages, the largest "woofers" are either the 6.5" diameter drivers as part of coax or triax or component systems, or 6"x9" woofers in coax or triax designs. Anything that's 8" or bigger is a "subwoofer."

So the naming conventions must be considered.

As such, the W15GTI is listed as one of the largest subwoofers, yet an examination of its characterisitics is instructive.

http://jbl.com/car/products/product_detail.aspx?prod=W15GTI&cat=SUB&ser=GTI

It's a sub that goes to 1kHz at the high end or down to 16 Hz at the low end. It'll handle 800W with 5000W peaks. To really get the measure of this beastie, plan on having a solid 500W just to warm it up.

As I wrote earlier, I'm not at all suprised it can whack the nuts off a 2235, and I think that given enough power it can beat the 2235 at both the low and the high end.

Now, whether you'd like the sound is another question. My opinion is that in a blind test, most people would pick the W15GTI, but in a sighted test, it'd probably lose, due in part to everyone knowing it's NOT a pro or high end consumer product--just a freaking low rider, ghetto blaster, ass-thumpin', tuner freak car speaker.

Really, it's so much more. :bouncy:

[Mr. Widget]

My opinion is that in a blind test, most people would pick the W15GTI, but ina sighted test...I give people much more credit than that. I find even the least informed and apathetic can hear when given the chance... the problem is far too often ignorance, not inability to discern the difference. Don't take my word for it... JBL and Harman's own studies prove it.


Widget

[boputnam]

Besides, everyone knows the 2245H was the king of bass. ;)Still is... :applaud:

[edgewound]

Simple chart of the results...

I'm sorry to dis the beastie, but this curve tells me the 2235 is the more accurate...read flat....transducer...in it's inteneded passband...flat to 1000hz.

They should both be test in their optimum enclosures for the definitive test....both at broken in spec.

[Ian Mackenzie]

I'm sorry to dis the beastie, but this curve tells me the 2235 is the more accurate...read flat....transducer...in it's inteneded passband...flat to 1000hz.

They should both be test in their optimum enclosures for the definitive test....both at broken in spec.

Until someone can tell me the point of this thread it should be moved to diy or off topic.

As JBL state "use for the intended application and the product will perform as intended"... . Car Subs are Car Subs, Extended Low Frequency Woofers are for Studio Monitoring and other Critical Playback Applications.

Close examination of the T/L partameters tells all.

Another case of doing the wrong thing for the wrong reasons...Frankenstien comparions anyone!

[norealtalent]

Damnit Ian, I was almost convinced to get 4 of them for my Westlakes!!! :)

[Ian Mackenzie]

There must be significant group delay in car subs...Bong...Bong...Bonk!

A long stroke helps..apparently,

David....Yeah well you can do what ever you like as long as your not quoting an original JBL Spec'd product..Heck..I thought what was what this forum was about.

A case in point...."..do coated 2235's out perform stock 2235's?..Maybe they were'nt aware of the aquaplas coating back in those days."

[norealtalent]

partial "..do coated 2235's out perform stock 2235's?..Maybe they were'nt aware of the aquaplas coating back in those days."

I seriously doubt it. If JBL could have improved the 2235 with a simple spray, THEY WOULD HAVE...:bouncy:

[johnaec]

So has anyone confirmed the rumor that the W15GTI is basically the same speaker as the 2266H, 381 mm (15") dia., 76 mm (3in) Dual Coil, Differential Drive®, Direct Cooled subwoofer used in the Vertec series?

John

[johnaec]

Oops! Were we supposed to? Well, as I recall, the subject has come up a couple times in the past, and I'm still curious. The 2266 lists for a lot less than the W15GTI, though...

John

[matsj]

It´s 2256g boys not 2266. They are realy close in parametrar. The carwofer is dual 6 ohm and 2256 is dual 8 ohm.


mats

[Titanium Dome]

I've not seen a VERTEC VT4882 up close, but I believe the 2266H is (was) also used in the SR-X Series (SR4725X maybe?). If that's the case, the relationship to the W15GTI is distant. It'd be like the W15GTI's shrimpy, older first cousin.

[matsj]

Sorry, 2256 is in vt4881 compact sub. I haven´t looked at al vertec´s. But Titanium Dome is right about 2266 is in vt4882.mats

[Titanium Dome]

or can make a good run at getting the gyst of it, then here's a thread about XLS subs that turns into bitch-slap between a JBL proponent who's representing the W15GTI as a pretty good alternative. He references JBL's whitepapers and seems to know a lot about the 2256, too.

Look for posts by Hasselhof in this five page thread, and his interaction with 3DX. There's some good ripping going on.

Maybe we should ask Hasselhof about this. He seems to have a lot of info at his disposal. Who's got some Danish chops?

http://www.hifi4all.dk/forum/forum_posts.asp?TID=20033&KW=xls&PN=0&TPN=1

[matsj]

I talked with hasselhof yesterday about w15gti and he knews alot about it. The man is very smart and knows much about jbl and crown.


mats

[toddalin]

Maybe you could keep us posted, Todd, on how they continue to behave over time. Your 2205/2235 is fairly new...how many listening hours do you think you have on them? The 2235 might wake up a little more down low with more break in. Just a thought.

They have been used a minimum of 4-5 hours a day every day since their install last December between Christmas and New Year... probably 80-100 hours at this point.

[johnaec]

It´s 2256g boys not 2266. They are realy close in parametrar. The carwofer is dual 6 ohm and 2256 is dual 8 ohm.'Looks like you're correct on the model number. But JBL's T/S parameters show RE at 3.1 ohms, so this is technically still quite close to the W15GTI's 2.95. All the other T/S specs are very close, but not exactly the same.

John

[toddalin]

I for one, would like to know more about how the data were collected... :)

All readings were obtained using a professional ($2,500) Quest Technologies 2900 Type II SLM that is re-certified on a yearly basis and has never been over 0.14 dBL off during it's yearly certification. The meter was set in linear mode (no weighting) with slow response. The woofer cones were monitored at a distance of 0.81" from the dust cap toward the center. The three ports were measured at the center of the port, even with the baffleboard. The contribution from the cone and each of the three ports was logrithmetically summed and considers the difference in the size of the port appropriately (port dBL + (10*LOG((2^2*3.14159)/(7.5^2*3.14159)). As it works out, due to the size of the port relative to the woofer, the contribution from each port is 11.5 dBL lower than the woofer at the same volume. (I.e., if the woofer and a port each read 100 dBL, the actual contribution from the port is 88.5 dBA with a net volume of 100.3 dBL.)

Even with these mic placements, cabinet resonences were notable. For example, both speakers would track various frequencies with dips and peaks observable at the port readings, but not so much at the cone. However, these tended to occur at frequencies where the port contribution is minimal and doesn't added measureably to the overall volume (<0.1 dBL).

Initially, the woofer was measured. The volume was adjusted until a sine wave of 180 Hz attained a volume of 100.0 dBL as measured at a distance of 0.81" from the woofer cap. The volume controls were left untouched and the frequency was swept to the various values both for the cone and ports. The sine wave generator is an older Bell and Howell unit from DeVries Institute. At the end of the test, the 180 Hz tone was verified still at 100.0 dBL.

As I said, if anyone is interested in the raw data, they're welcome to it.

[toddalin]

Until someone can tell me the point of this thread it should be moved to diy or off topic.



The topic is technical because it examines the technical aspects of the two speakers being compared. This was not a DIY and the thread should have remained where I initially put it!:biting:

[boputnam]

The topic is technical because it examines the technical aspects of the two speakers being compared. This was not a DIY and the thread should have remained where I initially put it!:biting: Er, actually, no.

Technical Help is specifically intended for JBL engineered goodies, in JBL engineered cabinets.

Interesting as they are, your cabinets are not JBL built, nor were these measurements collected by JBL using JBL authorized testing gear in a JBL sanctioned environement. Therefore, DIY is proper for this most interesting work.

For the beneifit of ALL our readers, it is hoped we can afffectively parse what is proper JBL, from what we try doing ourselves.

[toddalin]

Er, actually, no.

Technical Help is specifically intended for JBL engineered goodies, in JBL engineered cabinets.



If you weren't a Moderator, I would ask you to point me to the reference for this this quote.

[boputnam]

It ain't about being any Moderator - this is what Don discussed with all when the DIY area was proposed. It's to the core of the reason DIY was proposed. It doesn't mean any project is of lesser importance or anything like that.

It's just what I said:

For the beneifit of ALL our readers, it is hoped we can afffectively parse what is proper JBL, from what we try doing ourselves.

[Earl K]

Er, actually, no.

Technical Help is specifically intended for JBL engineered goodies, in JBL engineered cabinets.

Interesting as they are, your cabinets are not JBL built, nor were these measurements collected by JBL using JBL authorized testing gear in a JBL sanctioned environement. Therefore, DIY is proper for this most interesting work.

For the beneifit of ALL our readers, it is hoped we can afffectively parse what is proper JBL, from what we try doing ourselves.

- So, are you going to create a new forum for Altec & Lansing Manufacturing ?

- Or are discussions ( involving those 2 names ) meant to occur in this "DIY" forum ?

:)

[Earl K]

Todd,

- In case you haven't read the "genesis thread" on the leadup to the eventual creation of this "DIY thread" read "this" for some backgrounding (http://audioheritage.csdco.com/vbulletin/showthread.php?t=6714) . Slog through the entire thread .

:)

[Zilch]

Slog through the entire thread .Heh. Zilch worked pretty hard to get Don's "unequivocal" spec nailed down there.... ;)

Todd is, in fact, using the W15GTI as a subwoofer in his system, along with multiple 2235H's. I don't think he's actively considering replacing those.

In any case, he demonstrates here that Keele's nearfield low-frequency measurement technique (1974) can effectively discern performance differences between these two 15" drivers in that region using simple measurement tools. :thmbsup:

[johnaec]

Todd - 'any chance on doing some outdoor measurements on a warm SoCal afternoon sometime? A situation where you were relatively free of reflective surfaces, where you could lay them flat on their back on the ground, projecting into this hemispherical environment. Then, somehow suspend the mic overhead, about 10 feet, like JBL used to do in their early measurements. This way, any of the port measuring anomalies, etc., wouldn't be so critical. You'd just be getting a final objective result of the sum of the parts.

John

[Ian Mackenzie]

Sorry but the time difference makes it difficult to follow the discussion.
It just seemed what you were doing was a bit jumbled up and misplaced.

The thing about the DIY and Tech Forums does take a bit of getting your head around.....



1a. Well guys, the results are in. Comparable testing of the W15GTI vs a 2205 recently remagnetized and reconed (in Dec 2005) as a 2235 show the W15GTI the clear and present winner in the reproduction of bass.



1b. Both speakers are in the same enclosures and there is no reason that the results wouldn't be directly comparable.

2. It is also interesting to note that the W15GTI has a nice "hump" at 60 Hz whereas at that point the 2235 is starting to loose ground. From my experience with WinISD, I recognize that with the W15GTI, this hump could easily be smoothed out by further lowering the tuning of the cabinet which would further help the W15GTI go lower, and flatter.

3. The topic is technical because it examines the technical aspects of the two speakers being compared. This was not a DIY and the thread should have remained where I initially put it!


1a. Well that's a misleading statement and matter of opinion and presumptious at best.

1b. Refer to 1a.

2. I would like to see the W15GTI in the JBL specificed enclosure and measured again. The same applies to the other driver.

3. Perhaps if both drivers were tuned in individual ideal enclosures then measured it would prove to be a more satifactory comparison...woofers are not plug and play.

Nice bit of equipment though, would love to see some measurements of other know drivers and system under controlled conditions.

Ian

[boputnam]

- So, are you going to create a new forum for Altec & Lansing Manufacturing ?

- Or are discussions ( involving those 2 names ) meant to occur in this "DIY" forum ?I am not going to create any forum(s). I will merely attempt to parse stuff as seemingly appropriately, as I can. There will be errors, but we all work together to right things.

To the latter, anything DIY will go into DIY.

[boputnam]

:rotfl:

[norealtalent]

Partial- Why do we need to have a new forum for Altec & Lansing Manufacturing ?

Statistically, 23% of Americans are functionally illiterate. I don't think a new forum is the answer... but we can throw one in there to see what it does :D

http://indian-river.fl.us/living/services/als/scope.html

[Titanium Dome]

Statistically, 23% of Americans are functionally illiterate. I don't think a new forum is the answer... but we can throw one in there to see what it does :D

http://indian-river.fl.us/living/services/als/scope.html


I'm not sure these folks from Indian River are a good example to use, unless you were being sarcastic.
:dont-know


The statistics make it clear: illiteracy is on the increase in the United States. The Office of Technology Assessment (OAT), an analytical arm of the U.S. Congress, stated in a 1993 report:

"Standards and requirements for literacy have increased over time and a large number of adults need to improve their literacy skills. OAT finds that at least 35 million adults have difficulty with common literacy tasks

Apparently they don't know the literacy convention associated with acronyms, in which Office of Technology Assessment would become OTA, not OAT. Seems the US government at least gets it:

http://www.access.gpo.gov/ota/

[norealtalent]

I'm not sure these folks from Indian River are a good example to use, unless you were being sarcastic.
:dont-know



Apparently they don't know the literacy convention associated with acronyms, in which Office of Technology Assessment would become OTA, not OAT. Seems the US government at least gets it:

http://www.access.gpo.gov/ota/

Definately being sarcastic :D , couldn't help myself. :bouncy:

[Ian Mackenzie]

Thanks guys but I was not trying to stir the pot!

I just wanted to encourge thinking on the same page as to where and when posts are most appropriate.

It ocurred to me that ideally to do good measurements, a very large flat baffle would be required to measure both drivers and just alter the rear enclosure and tuning. Whereas if different enclosures of the correct volume where used for each drvier, this would without doubt cause a variation on the free field microphone measurements.

My earlier reflection on JBL testings was that they used an open field for such measurements or the roof of the factory at 8500 Bal Bvd.

Ian

[Steve Gonzales]

Please don't take this the wrong way, but I have a real problem with this thread's premise... Here we are comparing a subwoofer to a remarkably well balanced woofer. Other than seeing "as measured" that the subwoofer does indeed have greater output we really don't know anything about the relative quality of the two drivers in question. You probably could get a cheapo no-name sub from Parts Express and have similar results... that doesn't mean that it is a better woofer.

That said, I wouldn't be at all surprised if the W15GTI is a better subwoofer... the point is that the 2235 isn't a subwoofer. It is a woofer that is so capable that JBL found it acceptable to use it all the way up to 1000Hz in one application and use it as a sub in another... very few drivers are that capable.

Widget Cool response Widget, I feel the same about the 076 :)

[norealtalent]

Cool response Widget, I feel the same about the 076 :)
Now tell us what you really feel :p

[Steve Gonzales]

I think that what Mr Widget said makes a great deal of sense in regards to what a bunch of numbers say compared to the reality of what a transducer actually sounds like. :)

[Mr. Widget]

I think that what Mr Widget said makes a great deal of sense in regards to what a bunch of numbers say compared to the reality of what a transducer actually sounds like. :) Hi Steve... no flame suit required. If you go back and read the infamous ragged posts, you'll see that I never said that one sounded better than the other or that one was clearly superior to the other. I think that message got lost somewhere along the way... I have always advocated listening as the final test.

Here is the quote from that thread where in my mind the emphasis was at the end of the statement, but I guess you thought I was focused on the first half.



I will audition them at some point. While curves do not lie, they don't tell the whole story.
Funny thing is that I still haven't listened to my 076s... I do intend to one of these days, but it is down on my list. At present I am not using any ring radiators.


Widget

[4313B]

Well guys, the results are in. Comparable testing of the W15GTI vs a 2205 recently remagnetized and reconed (in Dec 2005) as a 2235 show the W15GTI the clear and present winner in the reproduction of bass. Furthermore, the W15GTI has a more extended high end.

Both speakers are in the same enclosures and there is no reason that the results wouldn't be directly comparable.

It is also interesting to note that the W15GTI has a nice "hump" at 60 Hz whereas at that point the 2235 is starting to loose ground. From my experience with WinISD, I recognize that with the W15GTI, this hump could easily be smoothed out by further lowering the tuning of the cabinet which would further help the W15GTI go lower, and flatter.Please read the following documents so you will have a better understanding of what a W15GTi is.

Page 3 of the owner's manual might be helpful:

W15GTi Owner's Manual (http://manuals.harman.com/JBL/CAR/Owner%27s%20Manual/W101215%20OM%20FINAL%20(revised%2092000).pdf)

The technical data sheet is helpful as well:

W15GTi Technical Data (http://manuals.harman.com/JBL/CAR/Boxes%20and%20Parameters/W15GTi_rev_f.pdf)

Using the W15Gti in SPL Competition (http://manuals.harman.com/JBL/CAR/Boxes%20and%20Parameters/W15spl_f.pdf)

Nice (?) hump at 60 Hz - Using BB6P this particular transducer would like to see a 6.5 to 9 cubic foot vented volume behind it with an 18 to 20 Hz tuning frequency. Resulting group delay is terrible. It can be seen by inspection that this transducer is extremely well suited to small sealed enclosures. In an automotive environment the resulting transducer/enclosure system automatically EQ's quite well.

With BB6P it can be seen that the 2235H would like to see a 3 to 6.5 cubic foot vented volume behind it with a 22 to 30 Hz tuning frequency.

Compared to the W15GTi, the 2235H has a more powerful motor, a rising response, and significantly greater efficiency. The W15GTi is not a direct substitute for a 2235H in systems such as the 4355 or 4430. I would not be surprised if the average person thought the W15GTi "sounded better" in a B380 enclosure.

[Titanium Dome]

Maybe I'll try that. I think the B380 cab is deep enough.

Where's that yardstick I got at the hardware store?

Should I stuff that hole thingy?

[4313B]

Naturally you would try it both ways. See what you think.

[johnaec]

The technical data sheet is helpful as well:

W15GTi Technical Data (http://manuals.harman.com/JBL/CAR/Boxes%20and%20Parameters/W15GTi_rev_f.pdf) That curve for the W15GTI in the recommended 4 cu.ft. cabinet tuned to 28 hz looks pretty good. Did you check the group delay for that, or just the larger 6.5 - 9 cu.ft.? (I guess I can fire up BB6P myself...)

John

[4313B]

It does? You like those thumpers eh? ;)

Just the larger volumes as per BB6P.