JBL 4355 clone with different woofers

[audiophile.1963]

Hello to all the members of this beautiful forum. I have been an avid Italian fan of JBL products since the 1970s and I own many JBL professional series components. I want to make a clone of the JBL 4355, but I would like to use the JBL 2226H I already own instead of the JBL 2235H woofers (2202H, 2441H with lenses, 2405H are in my possession). I know that the JBL 2235H woofers have a lower frequency response than the JBL 2226H (stratospheric? Are they close, is it a small thing?), That I will have to recalculate the volume and the tuning tubes and many other things, problems that, however, I will be able to to solve. My only doubt lies only in the answer below; is it a little or a lot? I would like your opinion, thank you and good day to all
Giuseppe

[Robh3606]

Hello Giuseppe

Why not try them out.

The woofers in that system are used with a limited bandwidth up to 300Hz or so. With them being bi-amped the sensitivity difference will work in your favor and the power handling of the 2226's is better than the 2235. If you run them in a box program you can see immediately what the on paper differences will be. Just be flexible when you build your cabinets so you can change your port lengths if needed.

In the real world the differences may not be as significant with music.

There will be a difference in the first octave 20-40Hz but on many types of music you should be OK. You can also add some EQ if needed. You are going to have plenty of headroom available with a pair of 2226's. You could run them in an assisted alignment with a bump filter if it works out in the box simulators.

If you are not happy then I would look for the 2235's.

Rob

[Mr. Widget]

Hello to all the members of this beautiful forum. I have been an avid Italian fan of JBL products since the 1970s and I own many JBL professional series components. I want to make a clone of the JBL 4355, but I would like to use the JBL 2226H I already own instead of the JBL 2235H woofers…

Since you already own the 2226Hs, I guess you have little to lose. They do have different cabinet requirements though.

Is building cabinets a simple task for you or is it a major effort? I ask because some people can bang out a set of cabinets in a weekend and others can take weeks, months, or more. If you are in the second category, I would suggest building the cabinets to the required 10 cu. ft. spec and place bricks, place mini boxes, or some other devices inside to bring the volume down to the required 8 cu. ft. for the 2226Hs.

You should plan on changing the port tuning to 40 Hz for the 2226Hs. These ports can be swapped out and replaced with ~28-30Hz ports if you decide to change your woofers at a later date. If the 2226Hs don’t work out for you, you pull out the bricks and have your 10 cu. ft. enclosures ready for 2235Hs.

Alternatively you might consider upgrading to a pair of 2216Nd. These woofers are available to buy new, and are a superior design to the 2235Hs and are intended for similar applications. These should work well as a drop in replacement for the 2235Hs.


Widget

[audiophile.1963]

“Is building cabinets a simple task for you or is it a major effort? I ask because some people can bang out a set of cabinets in a weekend and others can take weeks, months, or more. If you are in the second category, I would suggest building the cabinets to the required 10 cu. ft. spec and place bricks, place mini boxes, or some other devices inside to bring the volume down to the required 8 cu. ft. for the 2226Hs.”

I have no problem to built a prototype of the cabinet and my idea is what you suggest. Using an EQ, do you think that I could obtain a lower response (closer to 2235)?
Giuseppe

[Mr. Widget]

I have no problem to built a prototype of the cabinet and my idea is what you suggest.

Great, that is the right approach.

Using an EQ, do you think that I could obtain a lower response (closer to 2235)?
Giuseppe

Yes, but with limited max SPL output.


Widget

[RMC]

Hi Giuseppe,

RE" is it a little or a lot?"

4355 LF chamber internal volume is 265 L (9.5 cu.ft) and the box is tuned to 32hz (spec sheet). It doesn't specify if that LF volume is actually gross, or net after subtracting space taken by drivers, bracing, etc.

The 2235 is modeled by JBL using a 140 L (5 cu.ft.) box tuned at 30 hz with flat response (spec sheet)

The 2226 is modeled by JBL using a 140 L (5 cu.ft) box tuned at 40 hz but having a little droop in LF response (spec sheet), that's a small flag

In the JBL Enclosure Guide the 2235 is specified for 5 cu.ft. box (140 L) tuned to 30 hz

In the same Enclosure Guide the 2226 is specified (single) for 4 cu.ft. (113 L) tuned to 40 hz, and for double woofer 8 cu.ft. box (227 L) also tuned to 40 hz, that's another flag

The message here is 2235 is consistent in JBL's box data but 2226 cab size is not. I think there's some marketing in the 2226 5 cu.ft. enclosure. The explanation isn't new, 2226 is a sound reinforcement optimized driver where efficiency is king, that shows in the maximized sensitivity rating (97 db) at the expense of some lower bass capability. Whereas the 2235 was engineered more along the lines of a Hi-Fi woofer for VLF bass reproduction, however as expected at a lower sensitivity level (93 db). That 4 db difference may seem like a little but in reality, for the same type of system, its a lot and implies compromises had to be made to get to that higher sensitivity number. 2226 is not really a 30 hz driver, more likely a 40 hz one.

There are pitfalls associated with wanting to go too low with a woofer (in point form): risk tuning below Fs; QB3 LF alignment here, not a C4 which is a different story; down tuning puts more strain on woofer, VLF reproduced at a lower level; lower tuning than normal has unwanted consequence on driver output capability higher in the spectrum, displacement overload possibility (excursion); etc.

As for box volume reduction, i'd use old books instead or pieces of lumber (2X4, 3X3 or 4X4") as filling material placed at bottom back of cab, about a cubic foot+ in each. Books are lighter, easy to handle and to find. You can buy few stacks of cheap books at a flea market for little money, the story they tell doesn't matter here... Regards,

* Last minute reply to post # 4: EQ won't change the 2226 capability, it won't make it a 2235. On the other hand the EQ you have in mind would imply EQing below driver Fs and box Fb, this is risky business for woofer health. For my part and taste 40hz bass is quite acceptable, i live with that very well.

Richard

P.S. Regarding your initial question, charts/graphs exist where one can get an idea of proper volume cab and tuning frequency (even F3), without having to input and model data in speaker design software, just a little elementary math with Fs, Qts and Vas driver parameters. Its not Keele's Approximate Vented Box Design using the same driver parameters (have this also), its much simpler than that having to locate and multiply two numbers only in each of the three charts/graphs (Vb, Fb, F3). The drawbacks are it gives maximally flat LF alignments only, and its copyrighted material i can't reproduce...

Here's the results i got using this simplified quick modeling method for 2226 and 2235.

One 2226: optimum Vb 87.5 L (3.1 cu.ft.), tuning 48 hz, multiply Vb by two for double woofers

One 2235: optimum Vb 92-115 L (3.25 - 4 cu.ft.), tuning 29 hz, multiply Vb by two for double woofers. Graph resolution for this multiplier number wasn't great, using .20 or .25 as multiplier (the most likely) made a notable Vb difference in this case. So tolerance is a little larger here, i think 100 L or so Vb would be about correct (max flat).

Remember these are valid for maximally flat response only, typical users Vb would be somewhat larger, not everyone is seeking max flat, nor every project requires that either. Still gives an idea regarding "a little or a lot" for Vb. Based on the above, i think you will need less Vb using 2226 vs 2235, hence the 4355 box filling mentioned in case you change your mind about driver, and personnaly i wouldn't try to tune that 2226 cab below 40hz.

[audiophile.1963]

... I don't know if it is important, my 2226 is the version HPL
Giuseppe

[Mr. Widget]

... I don't know if it is important, my 2226 is the version HPL
Giuseppe

This is the standard H version but without the rubber tire around the magnet. It is essentially a lower cost version that JBL used in their own cabinets as opposed to direct sale version of the driver sold as individual raw drivers.


Widget

[audiophile.1963]

What do you think about this project?
https://mainkas.tripod.com/page/audi...ngen_sub2r.htm
Giuseppe

[Riley Casey]

I'm currently listening to a system with a single 2226H in an enclosure originally designed for a JBL1500F subwoofer driver tuned to 25h. I use an Ashly 4.24D DSP unit to provide step down equalization and crossover functions. The system works well down to 30hz and is high passed at 25hz. This is powered by pair of 60 watt amp channels in mono for a small living room area and crosses over into a pair of JBL 4828 speakers. For a larger area or higher listening levels than I can reasonably run in my townhouse I could easily go to a 300 watt amplifier without exceeding the power capacity of the 2226.

What do you think about this project?
https://mainkas.tripod.com/page/audi...ngen_sub2r.htm
Giuseppe

[RMC]

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

[audiophile.1963]

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.
Giuseppe

[RMC]

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.

[jbl4ever]

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

[RMC]

The info i have and gave you is for the "G, H, J" versions...