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Stuckinthe80s
01-24-2010, 05:46 AM
Hi, everyone. New to this forum, lots of great information here.

A brief synopsis: I came into a pair of D130 baskets that have been reconed with what is said to be 2225H kits. Currently, I have them installed in an existing homebrew 2x15 bass guitar cabinet that is (externally) 39" x 24" by 19", with an internal volume of 6.58 c.f. This cabinet has 4 - 3" id flared ports, 1.5" long. According to the T/S parameters of the 2225H driver, this has tuned the cabinet to approximately 56 Hz, as per WINISD. This setup is for my Son, who plays through a Markbass head, rated at 500 watts into 4 ohms. Right now, the rig sounds good to the ears with decent low frequency extension, and smooth midrange. The amp has never been above 12:00 and there is more than enough volume for any situation.

Questions: What T/S parameter should I use to model these? Should I leave well enough alone at this point? Should I scrap the project and rebuild with another design? I am unable to provide pictures at this time, but could early next week.

Earl K
01-24-2010, 07:55 AM
Should I leave well enough alone at this point?

I would , unless ( for whatever reason ) the desire is to simply build a different enclosure , .



Should I scrap the project and rebuild with another design?

As far as I can ascertain from your description, your project has successfully achieved its' primary goal .


What T/S parameter should I use to model these?

- A bonafide C8R2225 recone kit placed into a charged up D130 (F) magnetic assembly gives one an Alnico based 2225H transducer .

- Alnico magnetic assemblies are prone to partial discharge ( of their magnetism ) with heavy usage . Alnico S.R. ( Sound Reinforcement ) speakers generally suffer the most .
- Therefore, the net result of placing a 2225H cone-kit into such a beast ( that's partially demagged ) results in a transducer of unknown TS parameters .
- Fortunately, some of the parameters' movement away from spec. are predictable, such as :
(a) Bl product will be lower than normal, resulting in changes to
(b) "Qts" growing larger than is normal .
(c) Somewhat lower sensitivety ( a db or 2 lower ) .

- This all means, until you are able to purchase a TS parameter testing setup ( such as Smith & Larsons' : "Woofer Tester" ) / you can't really accurately model your woofers within different box alignments ( any more than you have ) .

<> cheers

Stuckinthe80s
01-24-2010, 08:31 AM
Thank you for the response. The cabinet has indeed achieved its primary goal, but has proven to be unwieldy for my 15 year old Son. I work out of town often, and cannot always be around to pack the gear for his shows. (He has a backup combo) This cabinet weighs approximately 95 - 100 lbs, FYI.

In fact, I am considering building 2 separate enclosures, the purpose of these would be to provide a more portable rig. (Approximately 45 lbs. each)

The vendor has indicated that they were re-gaussed by another shop nearby (I don't know how long ago) and are overstock from a large order he shipped a year ago.

Stuckinthe80s
01-24-2010, 08:44 AM
I am wondering about the power handling. The vendor suggests they should handle 200 watts comfortably. Is this fair? The amplifier itself is a digital power amp that has a tremendous amount of headroom, and while the master volume is never above 12:00, the dynamics presented during certain passages are quite something. I am currently running a dbx compressor in the effects loop, which seems to tame the worst spikes.

Earl K
01-24-2010, 10:36 AM
Hi,

- If you're confident that the 2225H cone kit is OEM from JBL & the vendors "recharge" story is legit / then use the 2225H ts parameters when modelling different sized enclosures in your software .

- 2 cabinets, 3 cu ft each, tuned into the low 50s, will work well with the 2225 woofer .

POWER HANDLING ?

- I've powered 2225s for nearly 3 decades with more than 200 watts each / and never burnt a voice-coil / or ripped the surround from over-excursion .

- Mind you, that's just me / as the "owner-operator" of my SR equipment , I always try to avoid costly repairs .

- I build in a VLF High-Pass filter ( on a graphic EQ ) / rolling off the sub-bass below the frequency where a ported box starts to "unload"
- ( ie; roll-off the low-end below the boxes Fb for maximum safety ) .

<> cheers

spkrman57
01-24-2010, 11:27 AM
Too bad you can't run them with a nice tube amp.

I think it would provide a smoother sound and less chance of burning out the voice coils.

Just my 2 cents worth of course!

Regards, Ron

Stuckinthe80s
01-24-2010, 01:37 PM
Hi,

- If you're confident that the 2225H cone kit is OEM from JBL & the vendors "recharge" story is legit / then use the 2225H ts parameters when modelling different sized enclosures in your software .

- 2 cabinets, 3 cu ft each, tuned into the low 50s, will work well with the 2225 woofer .

POWER HANDLING ?

- I've powered 2225s for nearly 3 decades with more than 200 watts each / and never burnt a voice-coil / or ripped the surround from over-excursion .

- Mind you, that's just me / as the "owner-operator" of my SR equipment , I always try to avoid costly repairs .

- I build in a VLF High-Pass filter ( on a graphic EQ ) / rolling off the sub-bass below the frequency where a ported box starts to "unload"
- ( ie; roll-off the low-end below the boxes Fb for maximum safety ) .

<> cheers

One is never 100% confident in buying used gear, but this fella has been around a long time and is highly thought of locally.

The high pass filter is a very good idea. I could hook up an equalizer in the sidechain circuit, and use the gating to cut off frequencies below, say, 40 Hz. Or something. Depends on what sounds good.

Thanks again everyone.