Mini dsp reverse engineering to make passive crossover

charlie2

Member
2012-10-27 8:45 am
Uk
I would like to build a design of speakers

Eg

Bass /mid/tweet

But using mini dsp and rew for measurements

Be it a a synergy or spendor bc1 design as examples

Using multiple amps of same source ie QSC 1450 rmx bi-ampping or trip-amping initially

But then can I make a passive crossover to fit and forget.

Running from a single stereo amp

How hard is it to do.

Cheers
 
I am just now finalizing a set of speakers using a similar process, miniDSP is invaluable for this. I initially measured FR of the raw drivers using nearfield measurements, then modeled a cross over, then began tweaking values until I got the desired FR and sound.

Here is what I started with

bf869ae7da0f669ac585cf8215b4e3b8.jpg


And ended up with

2de0abb7eccf58e94e0dccd6aaddc318.jpg


Final XO design
3cf70ae71a42b4d33f79256a60b87cc0.jpg


MiniDSP was invaluable for testing XO points, lpads and even the effects of Zobel networks. Also testing the effect of different FR on sound quality before making changes to the XO point.

I'll post a detailed wrote up in the next week or two but feel free to ask away.


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Lojzek

Member
2012-02-10 12:12 pm
Croatia
But then can I make a passive crossover to fit and forget.
Running from a single stereo amp. How hard is it to do.
Cheers

It's not hard to do anything if you know how to. I don't see
why would one go through the trouble of getting a dsp
solution and then try to do the same passively. Passive
speakers are trickier to deal with because you have to
work hard to find out a working filter that doesn't involve
an insane amount of parts. Secondly when you cross drivers
over at lower frequencies, the capacitive reactance part of the
woofer is causing spl differences so if this bothers you, then
you should add impedance flattening filters which adds to the
overall costs. My favorite design approach is passive filters
with woofer XO point pushed high enough to escape
the region I don't like without making significant compromises.

A good filter design is a thing of good practice and abbility to
think straight.
 
It's not hard to do anything if you know how to. I don't see
why would one go through the trouble of getting a dsp
solution and then try to do the same passively.



I can't imagine going out and buying a DSP simply for tuning one speaker, but if you're going to use it as a long term tuning tool then it's definitely worthwhile.

In my case I have a 4x10 already and a stack of amps


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