JBL 2225H with Mass Ring to 2235H or 2234H

[KCjblSound]

I’m looking to get a lower bass response from the 2225H. From all my research I have gathered the following:

2225H (2235H with diff cone/surround) - 40 hz

2234H (2235H without mass ring) - 23 hz

2235H (mass ring) - 20 hz

I would prefer not to re-cone as I prefer cloth surrounds. So I was thinking of just removing the dust cap and adding the mass ring, however from what I can tell this only lowers it 3 hz. Would this be the case? Has anyone tried this?

Also, is the cone actually different or is it just the surround and ring that provides the lower output?

[Kay Pirinha]

Who knows? The spider also might be of some impact on the TS parameters.

Btw, as the total mass contributes by it's square root to Fs, adding just the mass ring needs some recalculation, using the VAS and mass parameters you'd need to evaluate first.

Best regards!

[edgewound]

I’m looking to get a lower bass response from the 2225H. From all my research I have gathered the following:

2225H (2235H with diff cone/surround) - 40 hz

2234H (2235H without mass ring) - 23 hz

2235H (mass ring) - 20 hz

I would prefer not to re-cone as I prefer cloth surrounds. So I was thinking of just removing the dust cap and adding the mass ring, however from what I can tell this only lowers it 3 hz. Would this be the case? Has anyone tried this?

Also, is the cone actually different or is it just the surround and ring that provides the lower output?

I think this is what you're wanting. My customers are thrilled with the results. I call it a 2236H.

https://www.facebook.com/UplandLoudspeaker/photos/pcb.4488623814561357/4488621277894944/

[Kay Pirinha]

Due to several reasons Facebook needs to be avoided imho. So, what did you do, please? Is it a C8R2235 recone into a E140 basket?

T.i.a.!

[Robh3606]

I think this is what you're wanting. My customers are thrilled with the results. I call it a 2236H.

https://www.facebook.com/UplandLoudspeaker/photos/pcb.4488623814561357/4488621277894944/

Do you have T/S measurements??

Rob:)

[Mr. Widget]

Due to several reasons Facebook needs to be avoided imho. So, what did you do, please? Is it a C8R2235 recone into a E140 basket?

T.i.a.!Ditto.

Clicking on the link, I get this window. I am not able to access information from the Facebook universe and will not be changing my anti-social media settings.


Widget
.

[edgewound]

Do you have T/S measurements??

Rob:)

Just a few weeks ago, a new customer that was interested in my "2236H" kit conversion sent me these preliminary measurements. He brought me a very nice 2225H donor driver for the conversion. He ran some free air T/S measurements. These results were after running a sinewave at 7.5 volts/20Hz overnight. He's going to run some box tests in the next few weeks.

This is the email he sent me with his name redacted for privacy.


hi yet again Ken,


These are preliminary as I still haven't done a run with the driver entirely vertical (though final ought to be well within 10%):


fs = 22.83 hz
Re = 6.3 ohm
Qts = 0.37
Qes = 0.39
Qms = 8.63
Vas = 316.47 l (11.18 ft^3)
Sd = 890 cm^3 (I used JBL's 2235H specs)
Bl = 19.695 Tesla*meter
ETA = 0.94%
Lp = 93.01 db (2.83 V / 1 M)
Mms = 171.03 g
Rms = 2.9194 kg / sec
Cms = 0.2842 mm / N


Thoughts:


fs is perfect.



Vas / Cms is also very good, and lowers input power for my application.


Qts is somewhat higher than expected but I'll check later tonight whether the range is OK. As the spider is the same as 2235H and Mms is close, I'm wondering whether that's the surround as it's obviously stiffer than foam. Vas is ~32% lower than 2235H so that's a pretty good indicator.



However, the 2235H total Q is 0.25 which is still far lower than 0.37... this is baffling. I did note that the free air impedance peak is very high, nearly 140 ohms.



Fwiw, for your customers that use standard bass reflex enclosures in QB3 alignment, Qts = 0.37 is nearly perfect (Qts = 0.38 is perfect).



Motor strength is lower than 2235H, equivalent to 2226H. Strange as it's the same 0.75" coil in the same motor though the difference is not quite so large as the total Q.



Ref efficiency and sensitivity are excellent, equivalent to 2235H. I was a bit apprehensive about this and the results are reassuring.



Once I have the test jig set up, then I can use the measurement mic and obtain large signal distortion and guesstimate Xmax with a strobe light and ruler. Hoping for 7.5 mm+ at less than 10% THD... achieving this would be epic.



I'll run the calcs for the enclosures and biquad filters over the next couple of days though I am willing to make some accommodations for these drivers.


Thanks again,

[ivica]

Just a few weeks ago, a new customer that was interested in my "2236H" kit conversion sent me these preliminary measurements. He brought me a very nice 2225H donor driver for the conversion. He ran some free air T/S measurements. These results were after running a sinewave at 7.5 volts/20Hz overnight. He's going to run some box tests in the next few weeks.

This is the email he sent me with his name redacted for privacy.

Hi,

Interesting results

Regards
ivica