JBL project goes wrong, advice needed

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Have you accounted for the peaking response of the 2225H at 1.5kHz or is the 800Hz crossover just calculated assuming a perfect resistive 8ohm load? If the latter, this is probably your issue if it is too forward in the mids. Measure and model the crossover in software like Xsim. Also you might need baffle step compensation to bring up the bass.
 
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I have JBL 2225 drivers in almost 9 cu ft cabinets tuned to 31 Hz. My front baffle is 25 inches, and with the speakers positioned in the room corners, I get very good bass. Deep and hard hitting.



I just checked WinISD using your cabinet volume of 7 cu ft and the results are similar to my cabs. So don't give up yet.
 
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Have you accounted for the peaking response of the 2225H at 1.5kHz or is the 800Hz crossover just calculated assuming a perfect resistive 8ohm load? If the latter, this is probably your issue if it is too forward in the mids. Measure and model the crossover in software like Xsim. Also you might need baffle step compensation to bring up the bass.

i am using same crossover parameters/components than the 4671

2nd order 800hz 3.3mh/30uf, exactly what jbl calls for.

it is wired correctly

with some equaliser tuning i can get it to sound relatively better but so far i am disapointed of the end result. my cheap quest towers with two 6" sounds far better.

i am using parts express cross over eminence pxp2 but slightly modified. maybe i am maxing/saturating out the poor cross over i dont know, it is rated at 400w. my bgw is rated at 200wrms/8 ohm.

horn is reduced a lot with the help of the lpad.

the 2225h sounds more like a guitar speaker to me....

i simulated a lot of other speakers with winisd and the low response of the 2225h seems to dip a lot below 100hz.
the dayton dc380 seems to give far more better response with the same enclosure. but how far can i rely on winisd...i dont know

i simulated cross over with lxsim and it is acurate.
 

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You have put the JBL2225 in a much bigger enclosure then the original 4671. By doing that you also need to design a new crossover for it.
The cabinet tuning you made is called ELF or Extended Low Frequency. With a tuning like this bass goed deeper at the expense of lower sensitivity. You need to bring the midrange down compared to the cabinet tuning of the original 4671, otherwise you'll end up with 6 to 10db more midrange than low end. That's the reason why you don't hear much bass. So either make the encloure exactly the same as the 4671 (higher Fs) or design a new crossover for it. With a matching crossover all your bass will be back in spades.
You also need a matching crossover for this exact horn/compression driver combo. There is no such thing as a universal crossover for it. Without the right compensation circuit it will have too much midrange as well. That's probably the reason why the whole speaker sound more like a guitar speaker than a hifi speaker. Best advice is to invest in something like a MiniDSP Umik and make some measurements to see what's going on.
 
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You have put the JBL2225 in a much bigger enclosure then the original 4671. By doing that you also need to design a new crossover for it.
The cabinet tuning you made is called ELF or Extended Low Frequency. With a tuning like this bass goed deeper at the expense of lower sensitivity. You need to bring the midrange down compared to the cabinet tuning of the original 4671, otherwise you'll end up with 6 to 10db more midrange than low end. That's the reason why you don't hear much bass. So either make the encloure exactly the same as the 4671 (higher Fs) or design a new crossover for it. With a matching crossover all your bass will be back in spades.
You also need a matching crossover for this exact horn/compression driver combo. There is no such thing as a universal crossover for it. Without the right compensation circuit it will have too much midrange as well. That's probably the reason why the whole speaker sound more like a guitar speaker than a hifi speaker. Best advice is to invest in something like a MiniDSP Umik and make some measurements to see what's going on.

what kind/alteration of the cross over do you suggest ? lower cutting frequency ?
3rd order type ?
zobel network to compensate ?

thanks for the details. your explications are clear and clever to me. i designed the box this way because i wanted some more out of the 2225h but i screwed it all up it seems.
 
first experiment with a much bigger inductor in series. The JBL crossove has a 3,3mH inductor, try increasing this value first to 5,6mH or bigger. You will loss overall sensitivity but will get a better balance between low-end and midrange. You could also try to put an extra inductor with a resistor paralell to it in series of the crossover. Start with something like 4,7mH and 10 Ohm and experiment from there.
But it is undoable to give you an excact value without any impedance and frequency response measurements. All I can say for sure is that the 4671 crossover ain't gonna work, but you have allready experienced that yourself.
 
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first experiment with a much bigger inductor in series. The JBL crossove has a 3,3mH inductor, try increasing this value first to 5,6mH or bigger. You will loss overall sensitivity but will get a better balance between low-end and midrange. You could also try to put an extra inductor with a resistor paralell to it in series of the crossover. Start with something like 4,7mH and 10 Ohm and experiment from there.
But it is undoable to give you an excact value without any impedance and frequency response measurements. All I can say for sure is that the 4671 crossover ain't gonna work, but you have allready experienced that yourself.

thanks very much. i am making experiments there. i am not building a space shuttle.
so overall i want to try to reduce the cutt off frequency of the cross over right ?
 
No, you don't specifically lower the cutt-off frequency. The parallell capacitor stays the same to provide the 12db/oct at 800Hz. All you do is compensate for the rising response towards the midrange. In this cabinet tuning there is something around 6 to 10dB more midrange compared to the low end than in the 4671 enclosure. You need to compensate for that to bring it back in balance.
 
I have been trying to choose a high quality 15" woofer with good extended LF down to at least 30 Hz, and preferably to the low 20's. I've ruled out the JBL 2225 (or is it the 2226H or whatever - it don't matter).

Either I'm missing something with regard to VLF performance, or, it's really only good down to about 40-50 Hz.

However... What many people think of as "low bass", is really in the 100 Hz to 250 Hz range. So, you may have an EQ/driver balance/crossover issue.
 
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I have been trying to choose a high quality 15" woofer with good extended LF down to at least 30 Hz, and preferably to the low 20's. I've ruled out the JBL 2225 (or is it the 2226H or whatever - it don't matter).

Either I'm missing something with regard to VLF performance, or, it's really only good down to about 40-50 Hz.

However... What many people think of as "low bass", is really in the 100 Hz to 250 Hz range. So, you may have an EQ/driver balance/crossover issue.

i should have had ruled out the 2225 too from the start but there was a pair localy available when is started the project so....i work with what i have for now.
 
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How is your box on the inside, can you share a picture of the build damping and bracing? Double or single baffle? If your box is too big compared to the intended crossover design just fill it with sand. Is the driver new or old?

the box is made of 1" russian plywood (more ply than regular plywood)
no bracing since it is very stiff already but may need some. all glued with damping material on all walls.

the 2225h is a jbl speaker from the 80's era...undoubtly they are not new. they are in exceptionnal shape, barely worn, not reconed.
 
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