JBL 18 inch up to 300 Hz?

[mefisto]

Hi,

I would like to use a driver between 40 Hz an 300 Hz in a domestic environment. I was thinking about an 18 inch (2241) just to keep the excursion to minimum.

Is someone running such a large driver that high? How does it sound at the higher frequencies (300 Hz) compared to a smaller (15 inch) driver?

Thank you,

M

[Robh3606]

Look at the 4345, uses the 2245 up to 300Hz with no problems at all.

Rob:)

[rich carnese]

Just to play devils advocate, I believe, for home use, and for the range you specify..if you can find a 2231 (L136). you'll do better. If you can find an earlier alnico magnet model all the better. It can also be used in smaller enclosures (3-5 cu. ft is good) and will yeild reasonably flat response to 40Hz, and will sound better in the upper range. R

[Nightbrace]

Earth narrows down your location :).

[Nightbrace]

What about floating on an 11 dimensional membrane?

[moldyoldy]

Generally, a design shouldn't require a cone driver to reproduce frequencies with wavelengths smaller than the cone diameter, so the driver can operate in pistonic mode over its' full bandwidth. For an 18", this is approx. 700Hz, for a 15" it's around 1100Hz.

The main remaining issue is intermodulation distortion, which rears its' head when a driver has to deal with much more than 2 octaves.

Also for consideration is the effect of having an XO point in the midst of the musical fundamental range, but that's an unavoidable issue in multi-way broadband systems.

[Mr. Widget]

I would like to use a driver between 40 Hz an 300 Hz in a domestic environment. I was thinking about an 18 inch (2241) just to keep the excursion to minimum.I'd recommend the 2245 as it just sounds better to me... and to many others. I wouldn't worry about the excursion thing... unless you are you planning on SPLs of 120dB. If you are, use several of them.:D

Is there a reason you want to bandwidth limit the system below 40Hz?


Look at the 4345, uses the 2245 up to 300Hz with no problems at all.Yes and no... I personally think the 4345 would sound even better if the crossover was around 150Hz or even lower. It isn't really possible with that driver compliment and the ~300Hz XO was the best option... it isn't terrible by any stretch, in fact the 4345 is one of my favorite JBL systems, but for ultimate resolution, that massive cone does seem to cloud a small portion of the music just a tad.


Widget

[mefisto]

Thank you all for your answer, although I have some difficulties deciphering Nightbrace's recommendations. ;-) But then again, I am not the smartest guy around.

Dear Mr. Widget,

The bandwidth is dictated at the upper frequency by the horn I will be crossing over to between 250-300Hz. On the lower frequency, in my room, room gain starts at about 60-70 Hz. So I was thinking that the roll-off of the driver will be compensated by the room gain.

If there is a better driver for the intended puurpose, which will assure low distortion and high sensitivity please recommend it to me.

Kindest regards,

M

[hjames]

Thank you all for your answer, although I have some difficulties deciphering Nightbrace's recommendations. ;-) But then again, I am not the smartest guy around.

Nah, NightB was jest diggin' at you for using the oblique "Location: Earth" in the user details you "shared" with us ...

perhaps you'd bless us by a using a more specific point on the ol' globe ...

[Chas]

Actually, I am running 2245's 40-290Hz in my 4345's and it isn't bad at all. I plan to try substituting a pair of Alnico 2235's (easy to plug and play with Speakons, now :) ) and see if there is any difference.

The only immediate downside is that I end up with a lot of large boxes in the listening room....

[mefisto]

hjames wrote: "Nah, NightB was jest diggin' at you for using the oblique "Location: Earth" in the user details you "shared" with us ..."

Sorry, I did not realize that - I noted that I was not too smart. However, in my case it is rather true because I spend a lot of time in different parts on the Earth. Currently, I am in Munich, Germany.

Dear Chas,

Why are you considering the change? Once you get any results, could you please share them?

Thank you,

M

[whizzer]

Have you considered running one of several available JBL 10-inch drivers in between the big cone and the horn? Sub-enclosure requirements are minimal, so using a pair could be a possibility.

[Chas]

Hi, I actually was not contemplating a permanent change. I just thought I would give it a try for fun, since I have them kicking around.

My 2235's are in pairs mounted vertically with two vents at the top and two at the bottom. This arrangement always sounded nice to me in the mid-bass. I think this was partly due to the actual woofers being higher off the floor compared to the 2245/4345's. I.E. less coupling with the floor to muddy things up. This is just a guess though, on my part.

I recall that the articulation was outstanding with acoustic plucked bass on jazz recordings. I will post the results when I have time to do it.

[Chas]

Have you considered running one of several available JBL 10-inch drivers in between the big cone and the horn? Sub-enclosure requirements are minimal, so using a pair could be a possibility.

Nice idea:) . Any suggestions for drivers? I wasn't aware JBL still had any available.

[hjames]

Nice idea:) . Any suggestions for drivers? I wasn't aware JBL still had any available.

Try a pair of 2123s. I got mine off ebay, but perhaps available as JBL B stock perhaps. I saw a pair go recently for under $200.
... 250 W continuous pink noise power capacity. 76 mm (3 in) edgewound aluminum ribbon voice coil. 80 Hz-6 kHz response ...
http://www.jblpro.com/pub/obsolete/2123.pdf

Still waiting for my 4 way crossovers so I can tie them in with my 4320s as pseudo 4343s

[Ian Mackenzie]

We need to know more about the rest of your proposed system.

The problem of goinn up higher than 300hz (within reason) is not so much the driver but the effects of colouration from the interior of the enclosure back through the woofer cone. Larger boxes because of the panel sizes and internal dimensions produce box colouations. The normal use of bracing will help control panel resonance in the bass region and the fill (fibre glass damping) on the walls of the enclosure will absorb a lot of the energy and provide some degree of damping of the woofer at box tuning frequency.

However you should consider boundary layer pressure damping on the walls of the enclosure if you propose to run above 300 hz. Even at 300 hz crossover may help.

Sometime back I experiemented with this and had excellent results using bubble wrap on the walls and styrene pellets on the interior floor of the enclosure.

The 2245H was designed for a response without the need for boundary reinforcement like some of the other JBL 18 inch woofers. The 2241 is a different applciation of driver and its response below 100 hz is supported by wall boundary effects. The 2241 has higher sensitivity in the upper band area above 100hz but does not have the extension of the 2245 in terms of normalised amplitude response.

You may therefore find the placement and effects of room gain are important to obtaining smooth mid bass response .

Consider this alignment from Drew Daniels box calculator for the 2245H which I recommend for home use.

10.15 cuft 3 (net vol), Fb 27.3, Fs 32hz. The response is-.5 db down at 72 hz and -1 db at 46 hz and -3 db at 32 hz.

I have used this design with outstanding results biamped from 250-400 hz using an Audax 210HTO mid cone driver with the wall damping methods discussed above.

Ian



Hi,

I would like to use a driver between 40 Hz an 300 Hz in a domestic environment. I was thinking about an 18 inch (2241) just to keep the excursion to minimum.

Is someone running such a large driver that high? How does it sound at the higher frequencies (300 Hz) compared to a smaller (15 inch) driver?

Thank you,

M

[Thom]

This is not advice on doing this but rather a question to everybody with all the advice. Aren't there several JBL 18's that would be happier at 300 and be more easily acquired and go to 40? He didn't ask for 30. I know there are ones that say that they will. Is this a matter of those who write specs take liberties? I haven't really played with my 18's yet and that is why I'm asking and not giving advice.

[mefisto]

Dear Ian,

thank you for your reply.

Regarding your question about the rest of the system, I have two options. One is Tom Danley's Unity, the other is Steve's compression driver on appropriate horn. Both options sound good even below 300 Hz, so the 300 Hz cross-over point was selected based on reasonable size horn.

I do want to go with a sealed box below; to _me_ it sounds better than a ported design. I understand from Thiele's and Small's work that if one wants high efficiency (to match the horn in my case), this will limit the low end.

As Thom has noted (thank you Thom), I am looking for experience with 18 inch woofers at 300 Hz. If the consensus is, as some have already suggeted, that 15 inch is better there, I will sacrifice the low frequency extension for that.

In fact, if you look at my other thread (Help noob with enclosure aligment please), I have already looked at Altec 515B, and if one can trust the simulator, it can reach 104 dB at 40 Hz. Assuming 3 dB gain from stereo and 20 dB dynamic range, one is at 87 dB average listening level. Since my listening is on average 65 dB, I have another 12 dB overhead.

I understand that the Altec is not the best driver for the lower frequencies, but _I_ just love it for the mids. If however, there is a better driver, I would like to hear it.

Do I make sense or am I deluding myself?

M

[soundboy]

Been playing with this stuff many years, both for live sound, and home....used 2235H's and 2245H's and 2240's, and 2241's off an on for decades....my two cents is that for home "hifi" use, crossing any 18" higher than 80-100hz sounds too colored. The 2235H any higher than about 300 sounds too colored. It all depends on what your goal is....an 18 is an 18, at 300 hz....although the 2240H/ 2241 would sound a bit smoother than a 2245H, IMHO. To me, they are all too colored above 200hz, exept for live sound reinforcement......if you want a PA system in your living room, go for it...if you want uncolored, transparent music reproduction, use a 12 or a 15, with an 18 below 80hz.....
A lot of guys are doing the "PA" in the living room thing on here....that is fine, and a boatload of fun...it just depends on your goal. I prefer a more transparent wall of sound these days....asking which 18" woofer sounds best at 300hz....is like asking which model corvette carries the most luggage and kids:blink:

[Mr. Widget]

Been playing with this stuff many years, both for live sound, and home....used 2235H's and 2245H's and 2240's, and 2241's off an on for decades....my two cents is that for home "hifi" use, crossing any 18" higher than 80-100hz sounds too colored. The 2235H any higher than about 300 sounds too colored.... I strongly agree... however folks here will put on their best pouty faces and say, "but JBL used the 2235H up to 1KHz in the 4430/35 and the 2245H up to ~300Hz in the 4345 and those are both studio monitors so you must be wrong!"

The fact is JBL is no different from the rest of us... they have to accept compromises too.... when their sales literature is telling us the praises of one of their designs, they rarely mention the compromises.

So, yes you can use a JBL 18" to 300Hz and a 2235 to 1KHz.... I wouldn't, and I wouldn't try to take a lot of luggage in a Corvette either. :rotfl:


Widget

[mefisto]

Dear soundboy and Mr. Widget,

thank you for your answers, this is exactly what I wanted to know. Having established that, the logical question is, which 15 inch direver.

As I would like to use EQ a la Roger Russell's ML-1C, I was thinking about going with ferrite based drivers instead of AlNiCo to avoid potential demagnetization.

Perusing JBL drivers, 2215A looks rather nice, but I am ansure whether a ferrite drivers existed.

Thank you,

M

[4345]

Here is my system with 18" up to 800hz. Yes, I did think of the 4435 when putting this system together. I used to own 4435's and the sound is somewhat similar. The goal was to have a highly effecient system that was relatively simple.

There are probably some negatives to using the 2241 so high, but there are some positives to the system. I like the 2-way sound, the woofer and driver are very close and sound cohesive and the distortion of the 2" driver is very low. The system might be improved by using a non-JBL 18 that is a little less damped. I have heard a TAD TL-1801 18" woofer in a similar system that sounded very nice.

I am not a speaker designer or expert by any means. I wish someone with the expertise would give this a try. I think someone with the right knowledge and test gear could develop a very nice 18" two way system.

http://audioheritage.org/vbulletin/attachment.php?attachmentid=22917&stc=1&d=1171471993 http://audioheritage.org/vbulletin/attachment.php?attachmentid=22918&stc=1&d=1171472022

[Zilch]

There's no more dedicated pouty-faced practitioner of two-ways here than myself, and frankly, I don't see the point of struggling to use an 18" for LF other than bragging rights.

There's plenty of 12", 14", and 15" JBLs that'll do a better job of it. Use the 18" as VLF below that; they'll end up in isolated chambers anyway.

Though we don't have the unequivocal answer yet, (I suppose I could look for myself,) but it seems the two woofers in 4435 are isolated, no? DIY plans are in these forums somewhere....

[Chas]

Today I did some unscientific (non-pouty faced:p ) testing.

First of all, adding the two vertical arrays of four Alnico 2235's was quite visually intimidating. Sitting in front of four 15's flanking the two 18's in the 4345's and two sub-1500's in my reasonably sized listening room was a little uncomfortable to say the least! I wound up having a very imposing "wall o' JBL" 8-10 feet in front of me.

I switched the 40-290 Hz speakons from the 4345's over to the the 2235's, then adjusted for some obvious sensitivity differences. The 2245's were no longer connected to anything - note this did result in some sympathetic cone vibration on their part. I suppose the best thing would have been to hook them up to a power amp with no input attached. But, as I said, this was unscientific.

The results IMHO:

The Alnico 2235's win, hands down, when it came to articulation of a string bass while listening to Miles Davis's ESP album, the track I used is called IRIS. The 18's are a little murky and thick sounding. Bear in mind that in a 4345, the 2245's are fairly close to the floor. GT and Ian have mentioned this issue before.

None the less, Widget is correct. Why did I ever doubt him?

BUT, when it comes to bottom end weight and authority, EVEN with a 40 Hz fourth order high pass cut-off (and despite the fact that Giskard published a comparison of a pair of 2235's versus a single 2245 eons ago, that made them look fairly similar with the exception of displacement being slightly in the double 15's favor), the 18's win. There's something about these woofers. There is a low end weight that they present to me here that I haven't heard from anything else.

Apologies in advance for the blog-like ramble....

[Ian Mackenzie]

Perhaps you should articulate with Giskard as he is re engineering the stock 3145 filters:) .

The twin 2234 (4345) may have some appeal yet:) .

Ian

[Chas]

Perhaps you should articulate with Giskard as he is re engineering the stock 3145 filters:) .

The twin 2234 (4345) may have some appeal yet:) .

Ian

I'm not sure what you mean. In order to maintain a degree of brevity, I didn't go into a lot of detail. Perhaps, I should have; all the woofers under scrutiny today were driven directly with the same active, fourth order crossovers and solid state amplification. This may or may not be correct in absolute terms. It's just what I am using right now.

When I used to use my S-22 systems with a 2235H (sealed, 5 cu. ft.) crossed at 200 Hz (6 dB/octave) to the paired up 2235's below that, I often thought that a sealed 2234 instead of 2235 working 200 to 800Hz might be the cat's ass, though :) .

[Ian Mackenzie]

Chas,

I re-read all you post and think I see what you are doing:


Actually, I am running 2245's 40-290Hz in my 4345's and it isn't bad at all. .quote]

Can I ask why the 40 hz filter? This is going to influence with the subjective performance. I would prefer no filter unless you are running vinyl and then I would use 15-20hz but only on vinyl.

[quote=Chas;150151]

My 2235's are in pairs mounted vertically with two vents at the top and two at the bottom. This arrangement always sounded nice to me in the mid-bass. I think this was partly due to the actual woofers being higher off the floor compared to the 2245/4345's. I.E. less coupling with the floor to muddy things up. This is just a guess though, on my part.

I recall that the articulation was outstanding with acoustic plucked bass on jazz recordings. I will post the results when I have time to do it.

Can you post a picture? No we won't say your insane.:) What I meant earlier was I think Giskard would be interested in your impressions and your listening environment as some work is in the pipeline on the 4345. There are also members building these designs and no doubt they will read your post and go hey what.



I'm not sure what you mean. In order to maintain a degree of brevity, I didn't go into a lot of detail. Perhaps, I should have; all the woofers under scrutiny today were driven directly with the same active, fourth order crossovers and solid state amplification. This may or may not be correct in absolute terms. It's just what I am using right now.

When I used to use my S-22 systems with a 2235H (sealed, 5 cu. ft.) crossed at 200 Hz (6 dB/octave) to the paired up 2235's below that, I often thought that a sealed 2234 instead of 2235 working 200 to 800Hz might be the cat's ass, though :) .

Okay, I get it.

You are no doubt aware 4th order slopes are not necessarily going to give the optimum voltage drive to the 2245H and the 2122H. The likewise for the twin 2235H. The other thing is having other woofers in boxes in the room does make a difference even if they have the terminals shorted.

I do appreciate your posting this information and I have no doubt there are differences in the presentation of the 2245H and 2 x 2235H regardless of the conditions.

One thing that occurred to me earlier was Bo's comments on his 4345's (other 18 inch 300 hz thread) as his uses of some careful EQ settings via the KK graphic.

It would be interesting to hear from Bo on his graphic settings for the 4345 below 400 hz. Sorry I am not real good at editing posts!.

Ian

[Chas]

Ian, yes - I was trying to address the thread context only when I tried this experiment yesterday. Yes, the L-R crossovers may not be optimal for either driver combination based on G.T.'s comments in his 4345 posting last year. However, RTA measurements at my listening position suggest to me that it may not be so bad, either.

Like Bo, I am using EQ, but it's only in the loop below 290 Hz, once again my RTA and my ears suggest that it is not really necessary in my situation above this frequency. It does work wonders to tame the approx. 100 Hz, "room boom" over here though.

My 2245's are cutoff at 40 Hz because I am using a pair of SUB-1500's below this. I know this may well be overkill :D but it offers me some flexibility with regard to 4345 positioning and optimal sub placement for best LF performance in my room. It might seem like heresy to do this with a fine driver like the 2245, but given the positioning flexibility plus the reduced bandwidth drive to the 18's it can't be a bad thing in terms of distortion reduction either. I have no problem doing tricks at 18 Hz over here......

[Ian Mackenzie]

Interesting,

So can you tell us where the 4345 are located relative to the wall boundaries and relative to the 2235 enclosures?

I tend to find lateral movements are not in themselves enough to approach what might be called a listenable result. You also need to decouple or raise the entire system off the floor and play around with that relative to rear and side wall positon.

As I said somewhere else setting up these monitors can/is a PITA but it provide interesting results.

Ian

[Chas]

I am not keen on elevating my 4345's mainly because I like the MF/HF/UHF at ear level at an 8-10' seating position. Like everything else, you have to compromise somewhere.

My 4345's are about 33" from the rear wall and almost 24" from the side walls. I stuffed the two double 15 cabinets in between my two 4345's.

[JBL 4645]

Here is my system with 18" up to 800hz. Yes, I did think of the 4435 when putting this system together. I used to own 4435's and the sound is somewhat similar. The goal was to have a highly effecient system that was relatively simple.

There are probably some negatives to using the 2241 so high, but there are some positives to the system. I like the 2-way sound, the woofer and driver are very close and sound cohesive and the distortion of the 2" driver is very low. The system might be improved by using a non-JBL 18 that is a little less damped. I have heard a TAD TL-1801 18" woofer in a similar system that sounded very nice.

I am not a speaker designer or expert by any means. I wish someone with the expertise would give this a try. I think someone with the right knowledge and test gear could develop a very nice 18" two way system.

http://audioheritage.org/vbulletin/attachment.php?attachmentid=22917&stc=1&d=1171471993 http://audioheritage.org/vbulletin/attachment.php?attachmentid=22918&stc=1&d=1171472022

Gordon Bennett mate, the low frequency cab is the same that is used at the Empire Leicester square screen 1 for there THX design.:applaud:

If you look closely you can see the JBL 2241. So, I don’t understand it sounds like you need an active crossover for the whole thing.:)


http://forum.ecoustics.com/bbs/messages/47069/288071.jpg


If you not enjoying those with films like Star Wars Star Trek Die Hard Apollo 13 The Right Stuff, I’ll have them.:D

[4345]

Surely an active crossover would improve things. My set up was just a quickly done thing in order to see if the 18" woofer would go up to 800hz. I have some cabinets with 12" and 2" horns that I usually use.