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Old 1st March 2004, 10:59 AM   #101
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you can have a lot more combinations when you use the same resistors in parallel. like in the volume controls. for instance with 8 resistor you can achieve 256 combinations. like I think Nelson Pass uses in his crossover.
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Old 1st March 2004, 11:47 AM   #102
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Jens, read your site, very impressive. Now I understand as well why you want to go with normal opamps. The proposed super-active-x-over would become huge when using discrete opamps.

Nevertheless, the question is what is the target here. I would be interested in a model which has for 2 way one LP and one HP and that's it.

For three-way it would be 2 HP and 2 LP, so that the bass and the tweeter goes not through a bandpass.

I guess everybody needs regluators, inut and output-buffers.

It would be great to have on a separete board the option to EQ stuff like a super-treble-gain-stage.

I am with Promitheus: I want as well discrete opamps.

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Old 1st March 2004, 01:09 PM   #103
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I want a 2 way crossover with 12dB/octave filters with one equalisation for the woofer and one for the tweeter. I donīt think that would be too complicated even with discrete opamps.
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Old 1st March 2004, 01:39 PM   #104
grataku is offline grataku  United States
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You guys go ahead, I'll make my own boards, I won't accept anything that isn't in the spirit of the original moamps design and the pass design, ie balanced operation, discrete ICs and all adjustable parameters.
Mostly, I have big problem with someone with a clear commercial intent taking the whole thing over and making it a profit endeavor. Although it doesn't break any law it breaks my balls since I didn't make any money with the AlephX board.
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Old 1st March 2004, 02:02 PM   #105
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Default their putting up resistance

"for instance with 8 resistor you can achieve 256 combinations. like I think Nelson Pass uses in his crossover."

No he doesn't......... read the manual.

I looked a parallel resistor scheme. The problem it is not logical to program! There is a tremendous ease in use when you move a jump one to the right to increase frequency and one to the left to decease frequency.

However............ I did come up with a matrix that has more steps, less resistors, and a constant increment of 5K ohms per setting (jumper JB allows 2.5K increments that over lap a large part of the JA and JC range). For the 5K increments, only one jumper at a time is moved except when crossing the 25K/35K, 50K/55K, or 75K/80K step, which requires two jumpers to change. There is also no way to wire a short with the wrong jumper setting. There is only one jumper per 5 row section, R9 is to provide a DC path in case all JA to JE jumpers are pulled or to mount pot or audiophile resistor (if a final resistor value is chosen). The 5 row jumper sections also make it easy to see the position of the jumper. Having jumpered computer boards with 8 and more rows of jumpers I have bad memories of sticking the jumper on the wrong pin, after running out of fingers on my free hand to count with. Whatever jumper scheme you use lay all of them out with the same orientation and preferable left to right with increasing frequency increments! I have posted it before but here it is again:
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Old 1st March 2004, 02:27 PM   #106
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Default Adjustment of freq

Hello,

With balanced operation, how do you get around the component variation. I mean it's fine to have balanced circuit, bu what if the two "halves" are not identical, how does this affect performance?

What kind of adjustment is the best, moamps resistor ladder or something else (multi turn pots or a multi position switch?)

\Jens
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Old 1st March 2004, 02:27 PM   #107
steve is offline steve  United States
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Guess I will second the opinion that I'd prefer to stay pretty much with Moes design principles in this project... and though I plan to use this with 'chip amps' I would really rather use the descrete op amps in this application.
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Old 1st March 2004, 02:34 PM   #108
Raka is offline Raka  Europe
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I guess I'll also build my own boards, because I'd like to have the origininal moamps design. Besides, is not so difficult to build oneself another module to equalize whatever woofer you may meet.
BTW, JensRasmussen, thanks for your interest, your ideas look very interesting.
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Old 1st March 2004, 02:35 PM   #109
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well if you are going to use chip amps why use discrete opamps. You wonīt get much out of it and it will cost more.
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Old 1st March 2004, 03:15 PM   #110
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Smile To grataku,

To grataku,

I tried to email you, but it was not possible. Let me clear a couple of things up.

I have worked on a similar project as the one posted I this thread for some time now. The work is done in my spare time, and is completely non profit. I love signal processing and saw this as a chance to help out, since more and more people are making active filters.

Many people find them a bit difficult, why I made the manual I referred to earlier in the thread. I hope it has cleared up some questions, and even better made people understand that filters not are all that difficult.

I did not take over moamps design, look at the schematics I posted, the circuit is changed/improved to get rid of the problem with gain in the pass band. Furthermore our website has been created to allow people to download documentation of our designs for their own education and to enable people to make similar project them selves.

Please read our about. Thank you

\Jens
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