Musically subwoofer?

[Dr.db]

Hello,

I will have finished my stereo speaker projekt soon and I might want to add a real subwoofer to the system.
http://www.audioheritage.org/vbulletin/showthread.php?38804-Tribute-to-Lansing-Heritage-Forum-and-DIY-2405-amp-2446-amp-E145-build

I would prefer a sealed enclosure of about 3cubic feet....
I was thinking about the W15gti automotive speaker or the 2256g as the Sub1500 and W1500 aren`t available any longer.
But does the W15gti e.g. 2256g sound good on music?
Or are these only one-note subwoofers suited for home-theater?
Are there any real alternatives from JBL that are still available?

Besides that, I have considered the Aurasound NS18-992-4A.
It seems to be highly regarded and the motor-design is simply amazing. But a heavy membrane of 400gr mms seems too much to me for a good sounding woofer!?

Thanks a lot,
Olaf

[rusty jefferson]

https://www.parts-express.com/dayton-audio-18-ultimax-subwoofer-with-spa1200dsp-amplifier-and-cabinet-package--300-7200

I have a friend who recently received a review sample of one of these for evaluation and measurement for an upcoming magazine article. It measured and sounded very good. 4 cubic foot sealed box. You can also buy just the woofer/amp and build a matching box (or 2) for your system.

Your project looks great btw.

[toddalin]

I use a W15GTi in 4 cu ft and it sounds nice to me. You need lots of power, preferably into 12 ohms. (It's either 3 ohms or 12 ohms.) However, even it does not go as low as linearly as my Sunfire Signature. Together, they make a potent pair.

Teamed with the 2235 on the other side of the cabinet (in 6 cu ft) they make a very powerful trio, even with the 2235 padded down by 8 ohms in this configuration (~7 ohms combined impedience). Without the padding, the 2235 adds too much boom.

http://www.audioheritage.org/photopost/data//525/medium/Stereo_007.JPG

[Ruediger]

You should 1st define the required frequency range for the subwoofer, from lowest frequency to highest.

Ruediger

[DS-21]

I would prefer a sealed enclosure of about 3cubic feet....
I was thinking about the W15gti automotive speaker or the 2256g as the Sub1500 and W1500 aren`t available any longer.
But does the W15gti e.g. 2256g sound good on music?

Yes. You will likely need lots of EQ in a 3 cubic foot cabinet though. If you can, 3-4 W10GTi's distributed around the room and properly equalized will sound better in room

Another car woofer you may want to look at is the Rockford Fosgate 19".


Besides that, I have considered the Aurasound NS18-992-4A.
It seems to be highly regarded and the motor-design is simply amazing. But a heavy membrane of 400gr mms seems too much to me for a good sounding woofer!?

Not an issue. It's quite a bit "faster" than most 18" subs. Just look at how high it can play!

[baldrick]

My experince is that Aurasound NS15/18 is as good as IT gets... I'm planning om buying 8xNS18 to replace my 4xJBL 4645 (2258)

[Dr.db]

Thanks a lot for your input guys!

The required bandwith would be 25-100hz.
I have to deal with a monosubwoofer, allthough Im aware of the benefit of multiple subs spread in the room.

What enclosure would you recommend for the W15gti if soundquality is the priority?

What enclosure would be appropriate for the Aurasound?

Does the Dayton really keep up with the Aurasound or is it just a cheap alternative with less qualitiy?

[toddalin]

I did 4 cu ft, but is probably not optimum. In fact, this is probably about the smallest recommended enclosure. Run the Thiele Small parameters through WinISF. They are available in the JBL literature.

[Lee in Montreal]

Thanks a lot for your input guys!

The required bandwith would be 25-100hz.
I have to deal with a monosubwoofer, allthough Im aware of the benefit of multiple subs spread in the room.

100Hz is quite high for a home subwoofer. Anything over 60Hz can easily be located by ears. Most subs are cut below 50Hz.

Lee

[DS-21]

100Hz is quite high for a home subwoofer.

With competent integration of multiple subwoofers, 120Hz is fine. If you blend the subs into the mains (i.e. run the mains full-range and fold the subs in) then up to 150Hz can be optimum for smooth FR and max headroom without localization issues.

[Lee in Montreal]

According to the OP, he intends to use a single sub. If crossed at 120Hz, then that sub will have to be exactly between the two other speakers. Otherwise one side will sound more "meaty" than the other... BTW 120Hz is the frequency where the kick drum is felt. Imbalance can be annoying...

[toddalin]

Actually the THX standard calls for an 80 Hz cutoff.

[Lee in Montreal]

Actually the THX standard calls for an 80 Hz cutoff.

How many main systems start being weak at 80Hz? Computer speakers? ;-)

I have no clue how others use their subs, but in my case, I want to feel them. Not hear them. I use them between 20 and 50Hz to add a bit of thump. In my case, 80Hz is way too high as it adds bass that I can hear, not bass that I can feel. ;-)

Lee

[DS-21]

Actually the THX standard calls for an 80 Hz cutoff.

The THX standard was a crude rule of thumb before we could easily measure acoustic effects and didn't have cheap and easy-to-use DSP to integrate subwoofers with mains.

[audiomagnate]

I like crossing over to subs at 50 Hz, and I also like sub boxes larger than 3 cu ft., infinitely larger in fact (pun intended). I don't care how well it's made or how low it goes, a 3 cu ft box is going to sound like a 3 cu ft box.

[Dr.db]

If I´d use the W15gti e.g. the 2256g, 3cubic feet is almost close to Q= 7 in a sealed enclosure. Would there be a benefit in building a larger, sealed enclosure for these drivers?

I will locate the mono-sub very close to the mains, so locating-issues aren´t that dramatic.
I would propably use a lowpass at 80-100hz due to two facts:
- My main speakers (using E-145) start to roll-off gently at ~100hz
- every Filter creates some kind of group-delay and it gets worse the lower the filter is set

A 80hz lowpass-filter generates less group-delay than a 50hz lowpass-filter, resulting in a more time coherent system.
(I´m not using a DSP, so no way to set delays on the mains etc...)

[toddalin]

Regardless of whether you can localize the sound or not, if you don't cross it over at at least 80 Hz, you'll loose a least some of the ".1" in a home theater set-up.

[Ruediger]

See the thread named "JBL K140" in the "Lansing product DIY Forum" (which is THIS forum). Look for the patent granted to K.E.Stahl. Look for doctordate, he has done PCBs for such a project.

Basically the effective loudspeaker parameters are modified by electronic means.

Ruediger

[rusty jefferson]

Thanks a lot for your input guys!

The required bandwith would be 25-100hz.
I have to deal with a monosubwoofer, allthough Im aware of the benefit of multiple subs spread in the room.

What enclosure would you recommend for the W15gti if soundquality is the priority?

What enclosure would be appropriate for the Aurasound?

Does the Dayton really keep up with the Aurasound or is it just a cheap alternative with less qualitiy?

Below is a sort of spreadsheet of the 3 drivers we've mentioned. I know the Ultimax woofers are made in China and that's not necessarily great. However, it does appear to be a good sounding, and measuring driver for use as a subwoofer in the home. I don't make any claims about it's potential longevity.

You can see from the chart that if 4 cubic ft is the desired input (the reason I mentioned the Ultimax was your interest in a small 3 cubic foot box), the resonant frequency is considerably lower with the Ultimax meaning less eq and amplifier power.

If the desired input is changed to 30hz resonant frequency, the Ultimax would only need a 5.5 cubic foot box, while the Aurasound would need 9 cubic feet, and the JBL 11 cubic feet.











FS
19.5
20
25.2




QT
0.53
0.47
0.48




VAS
212.1
322
132.2












Input Desired Q






QB=
0.7














Driver
Ultimax 18
Aurasound 18
JBL W15Gti












FS
19.5
20
25.2
0



QB
0.7
0.7
0.7
0.7
0.7


QT
0.53
0.47
0.48
0



FB
25.75
29.79
36.75
#DIV/0!
#VALUE!










VAS
212.1
322
132.2
0











VB (L)
284.93
264.32
117.33
#DIV/0!
#VALUE!


VB (cu ft)
10.06
9.33
4.14
#DIV/0!
#VALUE!


















Input Desired Volume






VB (cu ft)=
4














Driver
Ultimax 18
Aurasound 18
JBL W15Gti
0
0










FS
19.5
20
25.2
0



VAS
212.1
322
132.2
0



VB (L)
113.26
113.26
113.26
113.26
113.26










FB
33.05
39.21
37.10
0.00
#VALUE!










QB
0.90
0.92
0.71
#DIV/0!
#VALUE!


















Input Desired Resonance






FB=
30














Driver
Ultimax 18
Aurasound 18
JBL W15Gti
0
0










FS
19.5
20
25.2
0



QT
0.53
0.47
0.48
0



VAS
212.1
322
132.2
0











QB
0.82
0.71
0.57
#DIV/0!
#VALUE!










VB (L)
155.17
257.60
316.85
#DIV/0!
#VALUE!










VB (cu ft)
5.480
9.097
11.190
#DIV/0!
#VALUE!

[hsosdrum]

Regardless of whether you can localize the sound or not, if you don't cross it over at at least 80 Hz, you'll loose a least some of the ".1" in a home theater set-up.
I doubt that the .1-channel information (in programs that even contain any .1-channel info) has any content at all above 50Hz – 60Hz. That channel is used for high-energy low-frequency information. Stuff around 80Hz and above would normally not be in the .1 channel, it would be in one of the 5 (or 7) full-range channels).

The primary reasons that THX chose 80Hz as the crossover point for THX home systems were 1) to keep the size of the L/C/R speakers small enough that they wouldn't dominate the room, and 2) because as a rule, humans cannot locate the source of sounds below around 100Hz (the wavelengths are so long — >10 feet — that they reach both ears simultaneously, and our brains rely on inter-ear timing differences to localize the direction a sound is coming from). As with just about everything, it's a compromise, but one that was chosen based as much on psychoacoustics as it was on Spousal Acceptance Factor.

I'm not sure what crossover frequency is used in the THX crossovers installed in THX-certified movie theater sound systems, but considering the size and low-frequency capability of THX-certified behind-screen L/C/R speakers it's no doubt lower than 80Hz. (Plus, localization isn't an issue in movie theaters since the subs are behind the screen along with the L/C/R speakers.)

[toddalin]

You've also got to consider that the theater subs also fill in for the surround speakers, and these don't necessarily have the bandwidth of the L/C/+R.

In fact, the "go to" JBL surround speakers (8330s) are rated from 70 Hz - 14kHz +- 3 dBA.

[Dr.db]

@rusty jefferson: Thanks a lot for your effort you put in the tables!



See the thread named "JBL K140" in the "Lansing product DIY Forum" (which is THIS forum). Look for the patent granted to K.E.Stahl. Look for doctordate, he has done PCBs for such a project.

Basically the effective loudspeaker parameters are modified by electronic means.

Ruediger

I have had a look on this but I believe I´m not familiar enough with all these parameters to really understand it.
http://www.audioheritage.org/vbulletin/showthread.php?8666-JBL-K140&highlight=jbl+k140

So far I understood this is no simple EQing, rather it is a manipulation of the drivers parameter with an electronical filter before the amplifier.

One questions comes to mind; how does this affect the drivers output capacities in terms of spl ?

[berga12]

a pro 18" with a Fs around 28-30hz not so heavy, and use a class D (quality ones...) with good amount of power.

I could say 2245h, but I never ear in my life one...

not below 18" for your speakers setup, and not a GTI.......yes tunderstorm but not quick enough. you need Speed to be "glued" to yours E145.

[Dr.db]

I think the maximum enclosure I could deal with would be 8 cubic feet...

So I would either have one Aurasound NS18 or two JBL W15gti.
Can anyone compare the sound of these two :confused:
I know that two gti would outperform one Aurasound in spl but which one sounds better with music?




@berga: Have you personally listened to the W15gti ?

[pos]

I had the opportunity to compare the W15GTI and 2245H, and what I found was that at "low" volume/excursion the 2245H produced far less distortion than the W15GTI.
The W15GTI has more excursion and power capabilities (ie higher SPL potential) but when you stay within its limits the 2245H is superior IMHO.
But of course YMMV ;)

[Dr.db]

Thanks a lot for sharing your experience.

What kind of encloshure had been used for the W15gti ?
Which freq. bandwith were they used at ?

[pos]

The enclosure was about 130 or 140L IIRC, I don't remember the tuning frequency.
My distortion tests where conducted in the <50Hz range.
Excursion noises can also be tested without an enclosure.

[Dr.db]

Sealed or vented ?

[pos]

vented

[JuniorJBL]

I use 4 W15GTi's (2 per 10 cu ft) and 2 2242H's (8 cu ft ea) in the theater. They all work very well for this application, however I still prefer my 2245's (8 cu ft per) in my 2 channel room for music. The ultra low distortion is far better with music IMHO. YMMV :)

I have only heard the others in theaters on movies.

[berga12]

Dear Dr.Db, I never Listen into home application with W15GTo subwoofer, but looking at the parameters I feel that it's not the right component for your application, maybe more suitable for home theater application, where distorsion is less important than SPL, and you don't care too much about timbric parameters.


you have to consider that you have a very quick and super clean 3 way system.

And what about Multiple 8" or 10" in a sealed enclosure? could be a possibility.

[Dr.db]

Allright, so the W15gti isn´t really musically when compared with the pro JBL drivers.

Does the Aurasound NS18 sound any better?
It has a very high moving mass as well...

8" or 10" drivers propably need tons of equing to rise the lows, as they start to roll of at about 50hz I guess.... Wouldn´t like that...

[berga12]

8"or10" can go down to 20-30hz but due to poor efficiency maybe you need 4-6 of them.

And you need expensive audiophile subwoofer....

you spend less with a single 15 or 18".

if you have aurasound ns18 give him a try!

[baldrick]

Allright, so the W15gti isn´t really musically when compared with the pro JBL drivers.

Does the Aurasound NS18 sound any better?
It has a very high moving mass as well...

8" or 10" drivers propably need tons of equing to rise the lows, as they start to roll of at about 50hz I guess.... Wouldn´t like that...

It's not that easy, many users think the W15GTI is great both for Music and home theather use! Some maybe not, but many do :)

But I would still buy Aurasound NS18, it's a fantastic driver... I've had a pair of NS15 and did prefer it over both 2245, 2242 and others. The only reason why I didn't buy them now when I bought wew sub was that I wanted to try the 2269h. Aurasound NS18 was used in i.e. Magico Qsub, the $36.000 sub!!!

[Ruediger]

A "musically"(1) "sounding"(2) subwoofer(3):

(1) It should not "sound", it should not add to the pure signal.
(2) What is "musically"?
(3) Cutoff frequency, box volume and efficiency are related with each other in such a way, that a gain in one respect results in a loss in the other dimension(s).

If the cutoff frequency is lower than required you give away efficiency and build a box which is larger than required.

My suggestion is to start with a proper Thiele design and to possibly fine-tune that.

Ruediger

[Kalle]

How about the BMS 18N862? 19mm X-max pro driver. It works in small sealed cabinets (150l) Cheaper for us that lives in europe to. A person I spoke to that uses this driver claims that it goes deep without losing its dynamics and snap like generally heavy cone drivers do. Some info: http://www.data-bass.com/data?page=driver&id=51

Regards
Karl

[Ruediger]

How about the BMS 18N862? 19mm X-max pro driver. It works in small sealed cabinets (150l) Cheaper for us that lives in europe to. A person I spoke to that uses this driver claims that it goes deep without losing its dynamics and snap like generally heavy cone drivers do. Some info: http://www.data-bass.com/data?page=driver&id=51

Regards
Karl

The TS Params from the manufacturers site are different (and better). Qts = 0.34, fs = 25.1 Hz, Vas = 312 liter.

Thiele alignment #5 is a B4, f3 = fs, Vb = Vas / 1.414. This results in f3 = 25.1 Hz, Vb = 221 liter.

Alignment #17 is a C6. It results in F3 = 17.5 Hz, Vb = 172 liter. Too much effort (active filtering) for an effect you don't hear or feel (no such signals on CDs).

Your speaker cables and amplifiers output resistance become part of the circuit. See formula 70 in the Thiele papers. This allows you to adjust Qt.

Ruediger

[Dr.db]

I´m still wondering which driver to buy...

Either two jbl w15gti or one Aurasound NS18.
Which one does sound better with music ?

The enclosure will be 6,5 cubic ft total.

[Lee in Montreal]

Simple. Get both and report.

[music2u]

Hi! I have seen the thread about your build: Wow.. thumbs up!

I have not auditioned the drivers you consider (and I would not trade my 2245 for any of them) but maybe some general considerations: Two drivers offer some flexibility:


you could run them in a stereo mode in two enclosures if you want
bass is in most cases the result of woofer and room modes. Two drivers may give you more flexibility with your room acoustic
you could build one subwoofer "impuls-compensated" to reduce enclosure vibrations

Having said that, the "Seismic" from Quint Audio (German Aurasound Distributor) is said to be a "beast"...

Stefan

[Dr.db]

Simple. Get both and report.

They are both not available here in germany, so I have to import them from the USA.
This will cost a lot of shipping fee´s and taxes, so I can´t buy both to try...



Hi! I have seen the thread about your build: Wow.. thumbs up!


Thanks ;)



I have not auditioned the drivers you consider (and I would not trade my 2245 for any of them) but maybe some general considerations: Two drivers offer some flexibility:


you could run them in a stereo mode in two enclosures if you want
bass is in most cases the result of woofer and room modes. Two drivers may give you more flexibility with your room acoustic
you could build one subwoofer "impuls-compensated" to reduce enclosure vibrations

Having said that, the "Seismic" from Quint Audio (German Aurasound Distributor) is said to be a "beast"...

Stefan

I´m aware of the advantage of two subwoofers, but I only have place for one enclosure.
Have you compared an impuls-compensated sub with a "usual" one ?
Is it just an advantage in theory or can one really hear a difference?

[Ruediger]

<snip>
Have you compared an impuls-compensated sub with a "usual" one ?
Is it just an advantage in theory or can one really hear a difference?
<snip>

... what an impulse-compensated loudspeaker is? Is there a reference :) ?

Ruediger

[Ruediger]

I did a quick check of the Aura Sound NS18 992 4A.

Thiele alignment #7 is a good fit. You end up with a box 441 liters large and with an f3 of 14.6 Hz.

The parameters box volume, f3 and efficiency are coupled with each other, so that if you gain something in one respect you loose something in another respect.

The efficiency of the driver is 86 dB, which is poor. The 14.6 Hz are useless, you pay for that waste with a large cabinet and poor efficiency.

The 14.6 Hz are useless because there is nothing on a CD below 20 Hz.

Ruediger

[music2u]

Hmm, I thought they are available here in Germany: http://quint-store.com/index.php?page=product&info=235

Impuls compensation is said to reduce the amount of energy that is lost in enclosure vibrations and therefore improve precision, because the impulses of the speakers cancel each other (sorry, I found only a German schematic):

75358

Elac uses that for their subwoofers and it is also used in the KEF Blade speakers. I have buildt open baffle subwoofers ("Ripole"). They are very close to the Linkwitz design. They are impuls compensated. But as they are open baffle, they do sound completely different. I belive that it works and measurements have been published in one of our German DIY magazines. But.....

Can you hear it? I don't know but I assume, that room resonances are much more important. That's why I currently build a DBA to compensate for the two 2245.

@dr db: My very personal opinion: The 2245 are the best I have heard and nicely fit into your concept. The enclosure and port tuning is documented here in the library. Try to get one, build a test enclosure. If you don't like it, you can always resell it with a very limited risk of loosing any money... Belive me: You won't...

[Dr.db]

Hmm, I thought they are available here in Germany: http://quint-store.com/index.php?page=product&info=235

Currently sold out, but will be in stock in summer again...




@dr db: My very personal opinion: The 2245 are the best I have heard and nicely fit into your concept. The enclosure and port tuning is documented here in the library. Try to get one, build a test enclosure. If you don't like it, you can always resell it with a very limited risk of loosing any money... Belive me: You won't...

I´ve read alot about the 2245 and they will probably sound very nice.
But I´ve been told, that they are limited in verylowfreq.-output due to their limited xmax. And I would need at least 2 or more to cope with my mains...



I did a quick check of the Aura Sound NS18 992 4A.
Thiele alignment #7 is a good fit. You end up with a box 441 liters large and with an f3 of 14.6 Hz.

The efficiency of the driver is 86 dB, which is poor. The 14.6 Hz are useless, you pay for that waste with a large cabinet and poor efficiency.


I believe the 86db is measured below 100hz and much more realistic than JBL´s specs in regard to the bandwith <50hz.

The JBL 2245h`s sensitity of 95db is measured above 100hz I think. As I´m using these below 50hz, whats their realistic efficiency down their ??
I´ve been told, one Aurasound NS18 will outperform two JBL 2245h below 50hz.

441liters seems huge, I´ve been told 250liters would correspond to q=0.7. And f3 was at aprox. 30hz...
Why did you get so different results?
14,6hz would be useless, thats absolutly correct. ;)

[music2u]

I´ve been told, one Aurasound NS18 will outperform two JBL 2245h below 50hz.


This is easy and not a question of belief: They are both 18" so about the same Sd but the Aurasound has an Xmax of 75mm and the 2245 of 25mm (peak to peak). So an Aurasound should "outperform" three 2245. If you want to break down your house, go and get a decent 2,000 watt class d amp (just kidding ;-) It is one of the most modern and technically sophisticated subwoofer driver out there. But does it match your "vintage" mains?

Before I started the JBL soundbar project, I also considered the Aurasound. I totally understand where you are coming from. From reading your post I believe your heart goes with the Aurasound. So go and get it. There's nothing wrong about it. It's all fun...

[Ruediger]

Impuls compensation is said to reduce the amount of energy that is lost in enclosure vibrations and therefore improve precision, because the impulses of the speakers cancel each other (sorry, I found only a German schematic):

75358

I have buildt open baffle subwoofers ("Ripole"). They are very close to the Linkwitz design. They are impuls compensated.


Hey guys, this is voodoo.

Ruediger

[berga12]

From the other side consider also that....more X max means Less Efficiency means more Watt to drive the loudspeaker and more distorsion.

I'm sure that the Aurasound is wonderfull speakers, the price is also not popular.

For an Home usage, your system (I'm speaking about 3 way one...) can be driven with a power from 1Watt to 12Watt with an Output > than 100db 1W 1m.

This Means, that It's enough to put 200W amplifier on a Single or dual 2245h (I would go with Single due to space need...) and The imput could be a combination L+R fully Active, and the main system fully passive without any High pass filter.

even if the 2245 have an average of 90-92db (I think more....) you can easily meet the same output as the main system without any problem, and you are able to shake your house if you want, or Just listen really clean without distortion at 100-105db output (definitively not a low volume...)

More over, you have a piece of history and a full JBL system. You can also try other speakers, for example M2 speakers 2216Nd, in 140L can go as low as 20hz...and many other in the market without the need of running a 18".

Pay attention on the subwoofer speed....you have a really quick response front stage...maybe one of the quickest 15"...





beside that...I also Love the NS18

[Dr.db]

Ok Rüdiger, I won´t worry about the impuls-compensation further more...


I believe one 2245 will be easily enough for the average day listening situation!
But I need the extra headroom for the days I go crazy and I think I would bottom out the 2245 then...

But there is one thing about the Aurasound which doesn´t please me; it is single 4ohm.
I don´t want to drive it with a cheapy plate amp, I´d rather use a professional external digital amp. But these are stereo, I haven´t found a mono-amp yet.
And bridging to the single 4ohm coil of the Aurasound would mean I need a 2ohm stable amp :blink:

[berga12]

Go with Hypex UCD module for a mono subwoofer, you will be happy.

you can use the mono module UCD700HG if you need more power, they also have 2000wrms module...

they can run 8-4-2ohm

Or If you have a dual voice coil, you can use a stereo amplifier on 4ohm x channel.

I'm using the UCD400 (2x) for my 2235h and they sound really nice on Bottom spectrum.

[music2u]

Hey guys, this is voodoo.

Ruediger

Is this solely your individual belief or do you have any evidence for your opinion? Have you measured enclosure resonances? Have you auditioned normal and compensated subs in direct comparison?

If you quote, then please in context. I also wrote:


Can you hear it? I don't know but I assume, that room resonances are much more important.

This is the reason why I usually stay away from forums.... :banghead:

[rusty jefferson]

https://www.parts-express.com/dayton-audio-18-ultimax-subwoofer-with-spa1200dsp-amplifier-and-cabinet-package--300-7200

I have a friend who recently received a review sample of one of these for evaluation and measurement for an upcoming magazine article. It measured and sounded very good. 4 cubic foot sealed box. You can also buy just the woofer/amp and build a matching box (or 2) for your system.......
The article became available today at audioXpress. You can download just the one issue if you like. Worth the purchase. Thorough article with measurements.
http://www.audioxpress.com/article/get-hands-on-and-up-to-date-with-audioxpress-february-2017-now-available

[gibber]

I´m aware of the advantage of two subwoofers, but I only have place for one enclosure.
Have you compared an impuls-compensated sub with a "usual" one ?
Is it just an advantage in theory or can one really hear a difference?

actio=reactio
said Galileo

No, it would rhyme nicely, but it actually was Isaac Newton.

So mounting speakers on opposing sides of a cab will cancel out that part of the reactio which goes into the wood of your enclosure.
You could build a single box with two speaker units, or you could even build two cabs in such a way that they can be bolted against each other firmly, if you want to "impulse-compensate". And hey, presto, if you ever move, you'd have two subs that can be used individually.

But back to the main topic of driver choice ...
If you go here http://www.lansingheritage.org/images/jbl/specs/pro-comp/2245/page2.jpg
you will read Vd is 1230 cubic cm or 1.23 litres. This volume is the max amount of air that 2245H can move. Vd simply is Sd * Xmax

Vd will determine your max SPL for any bass frequency. If you go down one octave @ that same SPL, your required Vd increases 4x.
If you want a certain max. level I would simply take the max SPL that your E145 pair delivers at 80 Hz.
==> needed SPL in your new subwoofer is already defined in some way.

(1) From E145 SPL, you could go and calculate the needed Vd (formula somewhere, for instance in Richard Small's Large Signal analysis paper) for 80Hz. Take the calculated value times 2 if your subwoofer uses only one driver to support two E145s. But it's much easier if you don't care for absolute SPL, see 2. below.

2) You decide how deep you want your bass, say 20 Hz.
Assume X/O of your E145 pair is at 80Hz. Then at 40Hz, you would need 4x, at 20 Hz 16-times the Vd of two E145 drivers.
This link http://www.jblproservice.com/pdf/thiele%20small%20parameters/theile%20parameters.pdf shows that a pair of E145 will offer Vd of 1.28 litres, and their max SPL at 80Hz fully utilizing 1.28 liters does not to be calculated. But sure is that for the same SPL at 20 Hz, you will need 20.5 litres of air moving capability. So 17 units of 2245H.

The above assumes closed box arrangement. Your E145 will not increase it's capability a lot @ 80 Hz if vented the way you have (low tuning).
Your 2245H @ 20 Hz would. Just assuming your port gain is 6 dB at 20Hz, you are down to about 4 drivers from 17.

==> for single driver subwoofer, there is no way around the Aurasound or similar large-excursion units, if you would like to maintain E145 capabilities all the way down to 20 Hz.

That does not automatically mean the Aurosound combines "musically" (thread title) with your super-low mass E145 units. And the last sentence is not there to infer that it doesn't. I simply have never tried it myself.
Try to find out and be sure i stay tuned as to your findings. Great work so far !

Ralph

[Dr.db]

Thanks a lot for taking the time ;)

Getting real subs that could mate the E-145´s spl would be ridiculous, I have to agree.
I would use the subs for average listening situations with moderate to high listening levels. If I want to go real crazy about it, I´d level the subs a little down or just leave them off...