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Crown XTI 1002 as active XO and amp


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#1 Kjelli

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Posted 02 September 2013 - 04:33 AM

I have built 3 X 2 way speaker using JBL 2435 HF (Modified with aquapl.)  and 2X JBL 2251J 10".

To drive these I'm using crown XTI2 1002, one for each speaker. The built in XO and dsp functions of these amps are great and gives good value for the money.

But i have one big problem, the HF is way to "harsh". At high levels it is painful to listen to.

Has anyone else any experience with using a XTI2 1002 like this?

If i put on filters that reduce the level of the HF the distortion is reduced, but this should not be required as the the JBL 2435 HF is a fantastic driver that can play really loud without any distortion, so I'm suspecting the XTI's to blame.

What am I doing wrong? should I activate the limiters on the XTI? Or is this just the way the XTI2 sound?

#2 dakos

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Posted 02 September 2013 - 05:21 PM

I'm sorry to tell you that I'm pretty convinced it's not the amps fault, few things, first of all JBL speakers are very well known for their harsh HF sound, just google "JBL+Harsh". As for the XTi, it's not supposed to change the sound unless you loaded some preset to it or changed the EQ settings so may be go back to the factory settings (do a firmware upgrede).

Did you also use an internal crossover?

This could also be the result of lack of other, lower end reproduction.
Avi

#3 joust

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Posted 03 September 2013 - 11:42 AM

Good question, Avi: Are the speakers configured for bi-amp application? The individual 'speakers' will need seperate input connection to bypass the internal crossover, if applicable.
Can they function as straight (normally loaded) speakers? Then, an internal XO is needed, and additionnal circuitry to bypass the bi-amping input connections.
Since the boxes are newly built, it is valid to ask if the boxes have an internal XO. Though, i would have added extra circuitry to bypass the internal XO, if it were to exist;

What is the impedance of the hi-freq load? Lo-freq load? Are these balanced? What is your 'proposed' crossover point?

Alain

#4 Kjelli

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Posted 09 September 2013 - 06:57 PM

Thanks for the replies guys. Ive been away a couple of days.
Anyway, i have read a ton about crossover design now and realize i should have had a better understanding of the basics before i startet this project. The speakers are fully active with no internal crossover. Separate connections to lf and hf. I do use a cap in series with the tweeter to protect it I connect lf and hf wrong some time in the future

The tweeter is a really expensive tweeter that should not be harsh (one of the few?). But my lack of understanding the basics of speaker design got me in a pit with regards to soundquality.

What I did wrong.
- i did not measure the tweeter and woofer separatly with a mic to find a good xo point. I thought it should be 1250hz, when 1800 was much better.
- i did not understand about step baffle comp. Failure to identify where this should start and include this gave me way too much treble. I had to use high shelf filter on both channel 1,lf, and channel. 2, hf to achieve this. Is there a simpler way?

After listening test now the harshness is gone, and my only concern is some resonances at a frequenzy oround 500hz. I think this can be solved with more stuffing in the cabs. I do have just a little stuffing in them now.

Some written guidelines to how to use the software to design a good crossover is deeply missed.
But now the speakers are really starting to sing :)






#5 joust

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Posted 10 September 2013 - 09:13 AM

Fantastic! Now, enjoy your speakers! :)

Alain