Pic of some JBL Concert Series
Since you mentioned the JBL 48 series (4828), i've looked at some of these 48.. Concert Series systems. Well, another place where JBL 2226 boxes (4870A family) are tuned to 40hz. The two VLF systems shown (4842A/4845A) use the 2241 (not 2226) for 30hz bass. I think for capability and reliability related reasons.
I was describing a "what you can get away with" scenario not in any way a maximum performance application. I don't have much need for substantial output at 30hz ( few of us do ) but with a woofer with power capacity to throw away against excursion I get satisfactory response which I think may be of use to the OP. The 4850 series boxes were taken from the original Stanal design that used 2220 woofers as they were intended for use with subwoofers in live applications. JBL changed that to 2226s to be able to market them for use without subs. The boxes really sounded a lot better with 2220s.
In the end, is my idea of using for this project the JBL 2226 right or wrong?
Thanks for all
Giuseppe
It will work try them, some loss of output 20-40 Hz and added sensitivity as far as being right?? Not if you want to have a stock system.
Rob
"I could be arguing in my spare time"
The project isn't perfectly right but its not totally wrong either. Tuning the box to 40 hz instead of 32 hz is not a big sacrifice in my view, with most program material, but it opens the door to the project being made. Its feasible and worthy. Consider other guys are also looking for 2235s, if they appear these may come at a premium...
MAKE IT WORK with the 2226 drivers you have, its not difficult. As i wrote before build a normal 4355 box with its dimensions. Then you adjust cab volume with old books inside to get 8 cu.ft. net. Tune it at 40 hz as recommended and approved by JBL. In case you don't like the sound, then you buy 2235s, remove the books and tune the cab to 32 hz with longer tubes, not complicated.
I never make test boxes, i don't need that, its a waste of time and material in many cases. Because, as i've seen here, people tend to put together a quick made cab since its "only for test", missing required attributes (bracing, sealing, gaskets, etc.) and expecting it to deliver representative results! Not so. A real test box must be as well-made as a final one (except finish) to provide proper indications. Instead i build one, well-made since it could become a final box (except finish), usually it does, test it, if ok only one more to go. If not ok only one box to scrap, or modify e.g. Lv. This avoids doing double the work.
The 4 db sensitivity difference on woofers (2226 vs 2235) is not a big issue here. The 4355 low mid/horn/tweeter are probably already padded for level matching between the drivers.
When making the new xo you'll simply need to pad the low mid, horn and tweeter somewhat less (say 4 db) to take into account the higher woofer sensitivity. So all components run at about the same 97 db sensitivity. If there's woofer correction in the original xo you'll assess/address that at the same time. Changes are possible.
If you have DSP you can add a boost/cut +6 db Q=2 filter to bring bass level up for improved flatness. If you don't have DSP you can mimic a similar filter with an equalizer boost and a HPF cut. My EQs have a slider at 40 hz, just the right place to add 6 db boost or so, where the vent does most of the work so it puts less strain on the woofer, gives an impression of stronger bass vs using none, and also minimizing the perception of too mid-bassy sound.
There's nothing too complicated here to get this project on the track and make it work. You do what it takes to get it done, plus its not that much different from a real 4355.
Richard
P.S. I'm including a new graph, same 300W, this time of 2226 in a 4 cu.ft. box tuned at 40 hz (a previous one was 5 CF/Fb 40hz). There's not a lot of difference between them, however here a B6 mimic filter would be a better fit based on response shown.
On the second pic you can see data for 2X5" vent tubes. Vent length seems appropriate for cab in this case. The minimum recommended vent area is 34.2 sq.in. and the two 5" tubes exceed this at 39.27 sq.in.
Also modeled 2X6" vents (not shown) might be too long at 17.7" for cab's real depth and require an elbow.
Here is some info that might help you
https://jblpro.com/en/site_elements/4648a-spec-sheet
http://www.audioheritage.org/vbullet...ormation/page3
This info shows what 2- 2226 drivers in the 4508 enclosure will have
If you make the crossover you will not need to pad the mid down.
2 -2226 in parallel 100/db the mid high's run 99db
Any small difference here can be made up with gain on the electronic crossover
agree, my bad for this one.
I calculated the net volume for each woofer in the 4355 cabinet (by removing the volumes occupied by each individual component, the volume of the mid bass box, etc.) and in the 4648 cabinet (considering a wood thickness of 2 cm, 3/4 inc ): I have 147 liters for the 4355, 117 liters for the 4648. I think I'll keep the largest size: inserting a cube of 31 cm the volume will be correct for the 2226. A curiosity, I saw that the front panel falls slightly, how much? 20 mm 3/4 inc +/-?
Thanks
Giuseppe
original 4355 uses 1" or 25.4 mm thick panels, the 4350B used 3/4" or 19 mm, i guess there was a good reason for this increase
I know, my question is different.Originally Posted by RMC
Giuseppe
Giuseppe check out image #10 for dimensions
http://www.audioheritage.org/vbullet...nclosure-Plans
A friend of mine suggests that I take the JBL 2204 instead of the 2202 and the JBL 2446 instead of the 2441, because the 2202 and 2441 are too old: is that good advice? In any case, the crossovers will be redesigned.
Giuseppe
The 4355 is an old design using old speakers. Thats only a problem if the 2202s and 2441s you have are somehow out of spec. Alnico demagnetized, cones or diaphragms fatigued? These are all things that can be tested prior to building the enclosures. Any given 2204 or 2446 may have similar problems ( well the ferrite 2446 won't demag in the same way but it can crumble ). More importantly those drivers have different characteristics than the originals. The 2204 was optimized to perform best about half an octave below the 2202 and that lighter cone difference is noticeable in trying to reach crossover above 1khz. The 2446 was optimized for higher output above 5khz for use without super tweeters and is somewhat less pleasant sounding over all than the 2441 for those compromises. It's always a trade off.
Measuring one of my 4350’s, the measurement you marked in red is almost 21MM or 13/16” total from baffle to the foremost edge of the angled trim.
Barry.
If we knew what the hell we were doing, we wouldn't call it research would we.
My project initially included:
JBL 2226 X 2 woofer
JBL 2123 mid bass
JBL 2425 + wood horn mid high
JBL 2405 tweeter
I changed my mind and abandoned this project because problems arose in the design phase of the furniture and so I decided to clone the 4355 using the 2226 but changing (obligatorily) the two central ways. For many years I have been buying used JBL components from a person of maximum trust and yesterday he proposed to me to buy 2204 instead of 2202 and 2446 instead of 2441. Before buying and making mistakes I ask you if it is a right or wrong choice. As I said in any case, the crossovers will be redesigned.
Thank you
Giuseppe
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