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Old 26th June 2012, 03:43 AM   #51
joexswj is offline joexswj  Indonesia
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what the greatest middle circuit for xo?
use linkwitz shematic before the xo and after...
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Old 29th June 2012, 08:20 PM   #52
tinitus is offline tinitus  Europe
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either you are very difficult to understand, or confused
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Old 1st July 2012, 03:21 PM   #53
gfiandy is offline gfiandy  United Kingdom
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Hi,

I haven't created an EQ, but if you would like a circuit for a state variable filter capable of matching the acoustic response of speakers to a L-R4 alignment this circuit should be able to do it.

It allows independent adjustment of the centre frequency and Q of each of a cascade of 2 x 2nd order state variable filters. So if you had perfect drivers you could adjust it to two Butterworth filters and have a perfect L-R4 alignment.

More importantly if you haven't got perfect speakers you can independently adjust the Q and centre frequency so you can create an acoustic response that matches an L-R4 alignment; including offset slopes or centre frequencies to adjust for time alignment between the Mid and tweeter.

Is this the sort of thing you are looking for? I have created LTspice simulatable circuits but I have not actually built it. Your welcome to the files if you want to play and see what it does. It does have a the notch output identified in the state variable filter so I think you could create elliptic alignments if you wanted to. (I haven't tried this)

If you did build this you will need some form of measurement system as there are too many variables to be able to set this up by ear. I was planning to use it to allow me to quickly evaluate different driver combinations but then the economy tanked and I lost my job in audio so it never went any further.

Regards,
Andrew
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File Type: pdf State variable filter independet V5.pdf (35.1 KB, 33 views)
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Old 1st July 2012, 09:58 PM   #54
brig001 is offline brig001  United Kingdom
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Thanks Andrew, sorry you lost your job - hope you get something soon if you haven't already. That looks like exactly what I was after.

I ended up with switchable 2nd order crossovers and basically just played with the switches and gains until I couldn't hear a difference when I swept a sine wave through the crossover frequency. Very crude but ended up with a nice sound. Just checked what I ended up with and the HF unit (1" dome) crosses over at 3750Hz and the LF unit (12" twin cone) at 9750Hz. This sounds like it shouldn't work, but does. I avoided 4th order because of the complexity of setting up, but will bookmark this for if and when I can get hold of some measuring equipment as you suggested.

Brian.
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Old 1st July 2012, 10:48 PM   #55
brig001 is offline brig001  United Kingdom
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Sorry, just check my calculations, and it should read 3kHz for the HF, and 6.6kHz for the LF.

Brian
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Old 2nd July 2012, 07:04 AM   #56
joexswj is offline joexswj  Indonesia
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Quote:
Originally Posted by tinitus View Post
either you are very difficult to understand, or confused
confuse,maybe.....
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Old 2nd July 2012, 04:39 PM   #57
gfiandy is offline gfiandy  United Kingdom
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Hi Brian, Thanks for the support, It was 2008 when I lost my job and I found a new one in environmental science within my notice period. Saving the world is all well and good but I do miss audio sometimes :-) skills transferred surprisingly well but I have had to brush up on science.

Would you like the LT spice files?

Regards,
Andrew
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Old 2nd July 2012, 07:20 PM   #58
brig001 is offline brig001  United Kingdom
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Hi Andrew, glad you got sorted, I remember when I was made redundant, with a pregnant wife, mortgage etc. all a bit stressful, but strangely interesting too...

Yes please to the LT spice files, not sure when I would get time to build it, but one day I hope to spend a bit more time on this.

Thanks,
Brian.
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Old 1st December 2012, 10:33 AM   #59
tinitus is offline tinitus  Europe
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I might have it figured out now
12db filter and a baxandall tone control with its centre placed at xo 'point'

on low pass filter you will be able to influence rolloff with 'tweeter' attenuation
only bass control works in the passband

on high pass filter its the other way round

time will tell if it works at all
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