i need and GOOD active XO

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#8
Slice -

I don't know what "too much money" really means... I know you're planning on spending 10K on amps...

If you want one of the best out there for a reasonable sum (~$1500) then buy a Bryston 10B. Keep in mind that this is a fully discrete audiophile unit.... Look here:

http://www.bryston.ca/10bcov.html

If you can up the ante higher then there's the new Pass Labs unit. I don't know the price but I'm pretty certain that it's quite expensive... I'm certain that it's also the best available bar none. Look here:

http://www.passlabs.com/prodlit/xvr1lit.htm

The Bryston is very good. It's about the most transparent crossover that I've heard to date. I've yet to hear the new Pass unit so the jury's still out on that one...

Good luck,

Steve
 
#9
Slice,

The Marchand is a good one for your application. You can buy it as a raw board, a kit, a semi-kit (where all the boards are assembled and tested -- you have to do the mechanical assembly and a little soldering), or as an assembled & tested unit. It is pretty good for a budget, op-amp based unit -- certainly better than the majority of the pro stuff that goes really cheap. I have one of the 2-ways that i built as a kit, and althou not the last word in transparency does the job until i can build my own.

Discreet devices are usually better, but not very available & certainly more expensive.

And there is the Marchand Tube XO -- it is quite expensive.

Being able to build your own, definitely puts a lot of flexibility into what you can do, and the place to start learning that is to buy one of John Pomann's Active XO experimenters kit which has enuff bits & instructions to let you really learn & play.
 
#14
Check the manual for Pass Labs crossover and Real Projects there. Although they have option for 24 dB they never chose it. When I got interested in crossovers in late '80s two good units available then where from Threshold and Audio Research. They both had 18 dBs slopes. I also tried 24dB crossover from Marchand but there was no contest. I have built Threshold crossover and I'm using it until today for my subs. I prefer not to use active part for mids and tweets because I'm loosing resolution. I just use series cap at amps input which combined with open baffle mids gives me at least 12 dB lope which I'm happy with.

24 dB is more work, you right about it Jocko. But it also means more complicated circuit and you have to run the signal twice through op amps (which I hope are not ICs). I just don't like it.😉
 
#17
By subtractive, do you mean it dosen't use feedback to filter?
I was wondering if it was possible to create a crossover that would work like some riaa type phono preamps- buffer the input and drive a passive filtering stage and then an output stage. Is this possible, and if so where could I find out about it? I don't like the idea of multiple complex IC op amp feedback filter circuits in series in the signal path.
Steve
 
#18
SteveG said:
By subtractive, do you mean it dosen't use feedback to filter?
I was wondering if it was possible to create a crossover that would work like some riaa type phono preamps- buffer the input and drive a passive filtering stage and then an output stage. Is this possible, and if so where could I find out about it? I don't like the idea of multiple complex IC op amp feedback filter circuits in series in the signal path.
Click to expand...

Pass uses a subtractive topology? Not in the XVR1. With the time delay to get the order of the subtracted section up? With 18/6 mentioned you get an awefully big bump on the bottom of the 1st order section.

A passive section between two gain stages is certainly doable -- in a PLLXO (with or without inductors) the two stages could be the pre & the power-amp. For more universal application sandwhiching the filter stage between a couple cathode followers would work.

dave
 
#19
Steve,

If you go to the Pass Labs web site you find the article on the x-over. The only drawback to this type of filter is the derived slope is only 6db per octave. A bonus is one of the filter elements could be passive but I would recommend a buffer.

Jam
 
#20
jam said:
If you go to the Pass Labs web site you find the article on the x-over. The only drawback to this type of filter is the derived slope is only 6db per octave.
Click to expand...

Thanx for the pointer to that article... it is a good supplement to the original Audio Amateur article i have somewhere.

As to higher order symetrical networks, Linkwitz i believe, showed how such a subtractive network could be done by adding an allpass with the same delay charater as the filter in front of the subtractive section forces symmetry.

dave
 
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