I am planning to build a very large 4 way horn system. I will use JBL cone drivers and JBL and Radian compression drivers.
For the bass horns I can choose between 2240 and 2243. The simuations are very similar. Will the 2243 sound better because of the more modern motor?
Mårten
Hi Marten;
I don't know the answer to your question since I have never had a 2243 but I do know I like the 2240 better in horns than the GTI 1800/2241's.
I am very interested in how this goes for you as I have four Community Boxer bass horns coming. I have 2240's for them but would like to know your impressions if you compare them.
All the best,
Barry.
If we knew what the hell we were doing, we wouldn't call it research would we.
Hi Marten.Originally Posted by more10
As a general rule, you want to favor the driver with the lowest QTs.
The 2243 has 0.19 and the 2240 has 0.23
Both drivers have an Fs of 30Hz
Lee
In the General Audio Discussions Forum see the Technical References Thread. There you will find the paper from D.B. Keele.
Ruediger
http://www.audioheritage.org/vbullet...l=1#post302559
Thanks for replies. There is a thread about 2243: http://www.audioheritage.org/vbullet...?3528-jbl-2243
Regarding driver parameters, the 2243 has higher BL than 2240. I believe it is just a bit too high
What I would like to know is how the more advanced motor of the 2243 will affect the sound. The 2243 has the same motor as the 2227. The 2240 has the same motor as the 2225. The 2243 is much better ventilated as well.
In the end I will end up trying both 2240 and 2243 :-)
I have made Hornresp optimized simulations, giving 20 Hz as lower frequency. 2240 is grey, 2243 is black. 2240 Performs slightly better because of 5,5 mm xmax compared to 5,0 mm.
The moving mass of 2243 is 182 g (6.4 ounces). Moving mass of 2240 is 130 g (4.6 ounces). The 2243 cone is a bit more durable.
Both cones are straight ribbed.
Hornresp can simulate pressure at horn throat. Do we have data on cone pressure limits?
I've used 2243 in bassreflex (not horn) and was in fact very surprised that the fs was as low as 30hz.
2243 kicks really hard and sound great above 40-50hz but below there really were not too much and I always thought 2242 was much better as "subwoofer", I've always thought 2243 more as a midbass/bass. As you probably know 2242 and 2243 are the same except the cone.
Thanks Baldrick! Horn loading is a bit different though. /M
Hi more10,Thanks for replies. There is a thread about 2243: http://www.audioheritage.org/vbullet...?3528-jbl-2243
Regarding driver parameters, the 2243 has higher BL than 2240. I believe it is just a bit too high
What I would like to know is how the more advanced motor of the 2243 will affect the sound. The 2243 has the same motor as the 2227. The 2240 has the same motor as the 2225. The 2243 is much better ventilated as well.
In the end I will end up trying both 2240 and 2243 :-)
I have made Hornresp optimized simulations, giving 20 Hz as lower frequency. 2240 is grey, 2243 is black. 2240 Performs slightly better because of 5,5 mm xmax compared to 5,0 mm.
can You give use some more info of the parameters You have applied simulating the mentioned bass-horn response.
It seems to me too promising (almost flat form 20Hz). I can imagine that pi/2 (in the room corner placement) has been the starting
expectation.
regrads
ivica
Hi Ivica. 3 drivers in paralell. Corner placement. I changed lower frequency to 20 Hz. It is huge :-).
Hi more10,
Definitely earth-quake or Saturn-5 rocket motor simulator,, especially in stereo version , two boxes: one per corner.
regards
ivica
Greetings Mårten -
A good starting point for choosing a cone driver that is suitable for horn loading is to determine the Efficiency Bandwidth Product. That will be fs divided by Qes. It's not the only criteria, but one that must be considered.
The EBP for the 2240 is 120. 120 indicates a vented enclosure, anything lower will indicate a vented to sealed enclosure. I couldn't find the T-S parameters for the 2243. As a good rule of thumb, the higher the number, the better the suitability. Also, the higher the number, the smaller the chamber volume is required for the driver, whether it be sealed or rear loaded. IMHO, what I know about current model JBL woofers are that none of them are suitable for horn loading. The 2240, and most likely the 2243 are better suited for vented enclosures. Don Keele vented the W-box he designed for the K151, but otherwise that speaker made for an unacceptable horn driver. I know, I built one back in 1976 after Gary Margolis mailed the plans to me.
The horn design program I have written indicates that the horn cut-off frequency is inter-related to the reactance of the chamber acoustical compliance, and the acoustical mass reactance at the throat, where both are required to be at unity. The chamber of a rear loaded horn is after all, an acoustical low pass filter. The fc for a typical horn loadable driver will be within five cycles below fs. That would make for a very long horn for a driver with an fs of 30Hz even if the throat area, St, is equal to Sd. Then there is the decision to chose an St based on efficiency or bandwidth, with efficiency requiring a larger throat, and bandwidth requiring a smaller throat. In order to design the horn to somewhat manageable dimensions, what you would end up with is a horn so short you would be lucky if it was able to provide a solid 100 cycles of support. Designing the horn to reside in a reduced solid angle such as a corner would help, but then you still have an undeveloped horn which would be considered a discontinuity between the horn mouth and room corner. Even if one considers the acoustic radiation at the effective length of the horn with a minimum horn mouth area, Sm, placed in a corner, it still may not support a fundamental frequency much lower than 40Hz.
An Example. The 130A / 2220A have an EPB of 194.7. Both of them were used in front and rear loaded horn enclosures with great success. The LE 15 has an EPB of 90.9. How many horn enclosures other than the Paragon was the LE 15 mounted in? None, and for good reason. Loading the LE 15 in the Paragon because it was JBLs' flagship 15" driver at the time was not a valid reason to do so. ALTEC woofers are another example. Only a few are suitable for horn loading, but their parameters dictate they need to be in a large volume enclosure.
I conducted an A/B comparison with a Paragon loaded with the 150-4C and the LE 15. The difference was startling. JBL should have never replaced the 150 with the LE 15, but should have replaced it with the 130A. Loading the Paragon with an LE 15 produces mushy, inarticulate, ill-defined bass, flawlessly. Some may disagree with me, but how many of them have conducted a side by side comparison? I wish someday that someone would publish T-S parameters for the 150-4C. It was JBL's best horn loader.
My recommendation is that you load which ever 18" driver you chose into a vented enclosure, you'll be much happier with the results. If you're dead set on using a bass horn for domestic used, I also recommend that you construct either a Klipschorn, or a C34 enclosure. The 130A or 2220 series will operate wonderfully in either of them. Or, the plans for the Klipsch Jubilee can be found on line. A pair of E120's or EVM 12L drivers in that box would sound awesome!
There is more to consider about designing horn enclosures other than reading a graph produced by a canned program. What looks great on paper, doesn't mean it's going to sound great.
Good luck,
H.F.
Drat! A double post.
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