possible subwoofer?

[mantisory]

Hi everyone,
So, I have a nice sounding system so far - JBL 2405, 2420 (in altec 511b) and JBL E145 in 4560 cabinet.
The bass drivers are powered by SS monoblocks, and the mid/high are powered by a SET 45.
I am currently using a behringer cx3400 for x-over duties (I know, I know - I will be getting a Marchand at some point I think), and also using a Sound Craftsman 2212 to equalize the highs since I didn't want to use an l-pad on the 2420 (which is ~5dB more efficient I think)
Anyway, in my room, it sounds quite good but doesn't quite have the low end grunt that I would like. Plus, there is a bit of a suck-out at ~80Hz or so, down about 10dB.
I am thinking I would like to add a sub...either some commercial offering such as a JL Audio Fathom 110, or possibly a DIY Horn-based sub. I really like the quickness and dynamics of this system so far and don't want to screw it up.
Anyone have any suggestions as to what would be a good addition to cover 15-100 Hz region? Also, are there any good systems for doing DSP on that region so that I can properly equalize any anomalies?
Thanks for your help!
Byron
p.s. - I don't really think I have enough room for more than one subwoofer - my room is ~12'x16' or so...

[Robh3606]

How much room do you have for the sub??

Yes E-145's are a bit challenged below 80Hz. They start to rolloff, you can 40Hz out of them but nothing solid below that.
I run DIY LE-14 subs under my E-145's and it sounds quite good. Won't get anyway near 15hz though. They are solid to about 25hz and then fall off the cliff. They are high pass filterd at 20Hz.

The Fathom subs seem to get great reviews. You could always try one if you find a dealer willing. You are not going to know how well it works until you get it home. A single sub will be a bit harder to integrate but it can work. I am using 2 for music the Le14's and 2 B380's 2235 woofers for LFE. All 4 are up for movies and the combo can move quite a bit of air. I think Velodyne offers a sub amp EQ box you might want to look at.

You could look at 2245 or a 2242 which uses a smaller box but 15hz?? 20 yeah 15???

Rob:)

[lbstyling]

I couldnt be happier with my 2242h sub myself.
You hear everyone rave about one sub or another, but I used build massive car installs for various competitions and have had many many home subs over the years- but this is the only one ive never felt I need to change. unlike everything else Ive tried (including a wall of (JL W7's), it actually gives detail in the bass. Ive had it 5 years now. If you have any way to audition one, give it a go!

[mantisory]

Thanks for the responses.
What kind of cabinet is the 2242H in? I am very interested since I will be able to keep things 'in the family'. I will be able to audition a fathom pretty soon...it may just work, you never know I suppose...but the idea of a horn-loaded sub seems very appealing as well!
byron

[Robh3606]

Do a search for 2242. There are several threads on building subs with them.

Rob:)

[Eaulive]

Yes E-145's are a bit challenged below 80Hz.

Specially in 4560s! :eek:

[mantisory]

Actually, they are great to about 35 or so...I will post the response graphs soon.

[Robh3606]

they are great to about 35 or so...

With EQ??

Rob:)

[Lee in Montreal]

I'd be surprised if much lower bass comes out of a 4560. I see it more like a midbass/medium cabinet.

52814

[mantisory]

I'd be surprised if much lower bass comes out of a 4560. I see it more like a midbass/medium cabinet.

52814

Don't think those will fit into my room :)
Anyway, not much low bass is correct. My response graphs are on my friend's computer and I am waiting for him to send them, but honestly they had decent output to at least 40Hz, if not 35Hz...They are in a relatively small room, so I am probably getting some good reinforcement.
Anyway, that's what the thread is about anyway...I want to extend the bass down and get some good punch as well.
Anyone here use a Tuba 30, perhaps? I think finding a JBL 2242/5 is going to be pretty expensive, but a tuba (or other folded horn) seems to be a reasonable compromise...
Byron

[Lee in Montreal]

The 4560's strength is 100-1000Hz. and not much below 50Hz.
Take a look at the response in JBL's own litterature.
http://www.google.ca/url?sa=t&source=web&cd=10&ved=0CFgQFjAJ&url=http%3A%2F%2Fwww.jblpro.com%2Fpub%2Fobsolete%2 Flow_frequency_enclosures2.pdf&rct=j&q=jbl%204560&ei=hFtrTvbNBMXJgQex57xO&usg=AFQjCNEoyR2NoERuzj977OoQdljBpl0NbQ&sig2=UpaAsCwUtYHNIjlCmW4prw&cad=rja

For home, You'd be happy with a 2245 in a simple bass reflex enclosure. Fs of the 2245 is 20Hz

[mantisory]

Here's a response measurement taken with EQ mostly on the highs, as the 4205 is 5-6dB down from the 2420/511b...There is a suckout at ~70Hz, likely a room node, and then there is one at the crossover point, ~650 Hz...but as you can see there is decent bass response...I really want to EQ that suckout out if possible, as well as just fill in the bass down to 20Hz or so...

http://farm7.static.flickr.com/6184/6134241042_da58ba2db9_z.jpg

[grumpy]

You can eq peaks, but boosting eq at nulls will likely prove to be a disappointing effort.
You could try moving the speakers or your listening position, or resort to room treatments... People write entire books and make careers as experts in this area.
You might look up Ethan Winer's web page as a start.

[Allanvh5150]

Chances are the drop off below 100 hz is the cabinet and the peak at 40 - 50 hz is the Fs of the driver. The only real way to fill in the drop off would be to build a new box.

Allan.

[Lee in Montreal]

The 40Hz peak is most likely room resonance. The 4560 doesn't go that low. According to JBL's own litterature, it has a useable range down to 50Hz. Not any lower.

[Allanvh5150]

The 40Hz peak is most likely room resonance. The 4560 doesn't go that low. According to JBL's own litterature, it has a useable range down to 50Hz. Not any lower.

Similar though to a reflex cabinet, the speaker will continue to go low and chances are, will kill itself in the process. All the 4560's I ever used had something else under them with an active crossover so I never saw this sort of thing. I was thinking it was the Fs of the E145 because it would be a big coincidence if the room resonated at the same point. Maybe but the Mic close and run the test again.

Allan.

[mantisory]

Thanks for the input guys. Yeah, I also thought that the first peak and valley are room related more than anything...but I still want to attempt cutting off the 4560 at ~100hz and filling in below with some sort of sub...
I will try the nearfield measurement when I get the mic back from my friend ;)
B

[Lee in Montreal]

Thanks for the input guys. Yeah, I also thought that the first peak and valley are room related more than anything...but I still want to attempt cutting off the 4560 at ~100hz and filling in below with some sort of sub...
I will try the nearfield measurement when I get the mic back from my friend ;)
B

Subs are to be used below 50Hz. Any higher than that, frequencies are directional and you will locate the source.

[Robh3606]

The 40Hz peak is most likely room resonance.

That must be one hell of a high Q peak. You have to have enough energy from the speaker to energize the room mode. No energy no peak. Based on my expereince with them I am looking at the measurement and scrathing my head. Where is the broad peak above 100Hz from the short horn loading the driver?? It almost looks like the horn and the 145 are out of phase??

You got me what's going on:blink:

Rob:)

[mantisory]

If it helps, here is the response curve with the phase overlayed...I am pretty well a newbie and am not quite sure what's going on with it either. Although the phase response doesn't look all that out of line does it?
http://farm7.static.flickr.com/6088/6136657279_119cd1117e_z.jpg
Thanks for the help,
Byron

[pos]

you have to align the impulse response to remove the initial delay in order to have a readable phase response

[mantisory]

you have to align the impulse response to remove the initial delay in order to have a readable phase response

Sorry, I am not sure what that means - this is the graph generated by REW with nothing added or anything by me...
byron

[Eaulive]

The phase response graph is generated by comparing the output of your speaker to a reference signal.
Since the sound from your speaker obviously arrives to the processor a couple of ms later, you have to delay the reference signal by the same amount so the computing is correct.

A correct phase graph should give you something like this:
http://www.audioheritage.org/vbulletin/showthread.php?30736-My-4520-project&p=319731&viewfull=1#post319731

[reVintage]

The 40Hz peak is not a room-resonant, it´s the ports resonance. By changing port-area it can be moved around a little, but also affects low-end drop. The dip at ca 70Hz is also due to 4560´s design. One can expect acceptable frequency-responce(for hajfaj) from 100-125Hz. So go for a sub from just over 100Hz. If the 4560 is corner-placed it can be used a little lower though.

If one reduces the chambervolume to ca 100dm3 instead of the original 220dm3, things begin to look really nice as the response gets straighter with the big dip and peaks smoothened out. We will be able to x/o against the sub at 60-70Hz.

[mantisory]

The 40Hz peak is not a room-resonant, it´s the ports resonance. By changing port-area it can be moved around a little, but also affects low-end drop. The dip at ca 70Hz is also due to 4560´s design. One can expect acceptable frequency-responce(for hajfaj) from 100-125Hz. So go for a sub from just over 100Hz. If the 4560 is corner-placed it can be used a little lower though.

If one reduces the chambervolume to ca 100dm3 instead of the original 220dm3, things begin to look really nice as the response gets straighter with the big dip and peaks smoothened out. We will be able to x/o against the sub at 60-70Hz.

Thanks for the info Lars. I am not sure how I would go about reducing chamber volume. I think I am just going to go ahead with building a sub, either based on a 2245, or possibly a Tuba HT, and then cross over ~100Hz or so.
B

[Robh3606]

If one reduces the chambervolume to ca 100dm3 instead of the original 220dm3, things begin to look really nice as the response gets straighter with the big dip and peaks smoothened out. We will be able to x/o against the sub at 60-70Hz.

What software are you using to determine this?? Reducing the volume for the reflex portion will not give you a lower useable frequency limit with this driver. If anything you would need to increase the volume to extend it.

Rob:)

[reVintage]

Hey Rob,

The hornreflexes(A7, 816, 4560, 4520 etc.) are very hard to handle as they are big compromises. You get shelving as as the horn has higher sensitivity. Also you get phase problems, giving dips between the horn and BR. As I remember Roediger has pointed this out earlier using the same software. But it will good enough with a higher XO. We have got quite good IRL results with 816/416 crossed at 350Hz to 200Hz LeCleach-horns.

The only reliable software is Hornresp. See below, original first and then Pi*1,0(wall/floor). With 2205A as E145 has totally wrong parameters in JBLs list. Maybe E-140 is more like E-145, haven´t tried that, though.

Highend response will be straight a tad higher up due to onaxis-response, the simmed are constant directivity. Note the 100dm3 version has a higher sensitivity in lowend almost eliminating the shelving.

[grumpy]

IIRC, the error is for Vas, listed as 274.7 and should be ~427 (for E-145)

[reVintage]

Hey Grumpy,

Thanks a lot, will do some new sims. Assumed it was VAS but didn´t care to use the std formulas to find out:o:.

By the way JBL are one of the few manufacturers that(normally:)) has correct T/S-parameters. Also Altec, but I have only compared their data of 414 and 416 with reality.

EDIT: Had to try at once and now we´re talking! Original to the right, not so exiting, as expected. 100dm3 volume to the left. Sims are in 1*Pi= floor /wall placement.

Both should be useful up against 800Hz on-axis. Maybe more if direct radiation works. Can´t be shown together with combined as above. Have simmed it with the directivity function though.

With a 60-80Hz sub we´re home!

Maybe one could cut the rear of the 4560 to reduce volume. We are very much alike Altec 816 now.

[mantisory]

Ok, well, I think I am going to build a sub and x-over around 80Hz. With the Marchand XM44, I can get a number of 'frequency modules', so I will get one for 70 and 90hz as well, and go from there.
Thanks for the help guys.
As far as reducing the cabinet size, or removing the rear panel, etc, I am not sure how I'd proceed, so I will just use them as is...
Byron

[reVintage]

Hey Byron,
If you decide to keep the original volume you can change the port-area to get a better compromise. Go for a total of 400cm2, ie 100cm2/port, when placed rearwall/floor(1*Pi). If going for corner placement(,5*Pi), 300cm2 is a good start.

For those wanting to cut a 4560, you should cut all above the horn(all reflex-openings at the bottom) and also block the cavities at the hornsides. Volume will then be below 150dm3. Looks OK in 1,0*Pi:

[mantisory]

So...I still haven't done anything about all of this. I am pondering either building a Tuba HT or something similar. Or perhaps I could try to locate a pair 4520 bass horns instead? I am not sure at this point which direction to go...I still don't quite understand the past few posts regarding changing the cabinet volume, etc.
thanks again,
byron