MOX active crossover buy

[Coulomb]

Originally posted by tiroth
The order is in! There were a total of 87 orders. I'll be donating at least $1 a board to DIYaudio once I get I verify the orders are correct.

I should receive the boards on or before May 20th. The annual is coming.

I've ordered additional boards, so I'll continue to accept orders as long as I have boards available. Thanks everyone.

You mean Manual correct?

Anthony

[tiroth]

Quite so--an amusing typo. Perhaps more sleep is advisable?

I was actually expecting more than 87 boards, but my minimum was 50 and that was no problem. Definitely a success. I'd really like to get some of Jens' improved MOX boards ordered because MOX and MOXlite should work in tandem--design on one, build on the other, and reuse MOX for the next project. Hopefully in 6 months or so I'll put another buy together that elicits more interest.

[AndrewT]

Tiroth,
you must need that sleep.
Annual means publish each year and now you are talking about putting yourself through all this again in 6 months.

[BobEllis]

I am interested in an I-MOX buy, whenever you are ready, Tyler. Not that I don't already have too many projects in various states of incompletion.

[JensRasmussen]

Tyler,

I will see what data I can find for you for the MOC mk. II

\Jens

[AndrewT]

Hi,
Moxlite schematic shows unity gain filter blocks. This is not the same topology as mox.
I see that unity gain can give B2 and cascading 2 sets will give L-R4.
How do you get B4?
I thought the whole idea of mox was an easily adjustable filter set to experiment with active speakers until one had them sounding just right. Then use moxlite to implement the final filter.
But how does unity gain meet this requirement?
What am I missing here?

[AndrewT]

Hi,
now going one step farther.
Can moxlite be modified either by track snip or by hard wire p2p to form MFB filter topology?
This mod is easy if gain adjustable filter blocks based on EVS&K are used.

[tiroth]

The only difference between the designs is that MOXlite doesn't need the clever circuitry for Q adjustment, since you already know the Q when you design the filter. In fact, for the Q=0.5 case, the filter components are identical between MOX and MOXlite. For other Q, they just need to be scaled appropriately.

As for compatibility with MFB--let me know if you know of a different MFB topology. As it stands, I don't see that they are remotely similar.

[AndrewT]

Hi Tiroth,
I had not read all the MOX threads and only just found that Moxlite is only unity gain based.
Yes, you can scale the R's and/or the C's but the maths is quite complex (for me) and is only recommended for Q <=1.1
if Q>1.1 the gain should be set for >1. This is the situation for the B4 filter when Q of one stage is 1.307 and optimum gain should be 1.31 to minimise error due to component tolerances.
Yes, the schematic for MFB is exactly as you attached to post 108.
The similarity is that both are 2 pole filters and when you draw the unity gain (moxlite) inverted with the -ve input at the top you find the component placement is almost identical with just a few track swaps and 3 extra resistors. Similarly if you compare the inverted layout of an EVS&K (mox) again component layout is even closer and this time only 1 extra resistor is required.
The advantage of EVS&K is independant setting of Q and accurate selection of frequency Rs & Cs without scaling. The advantage of MFB is independant setting of both gain and Q but at the expense of scaled Cs but you can obviate this by //ing identical Cs for the lower limb with good matching accuracy if board space is dedicated to the Hi Q filter.
All of this only applies if you want filters other than B2, B3, L-R4 and L-R6.
Maybe some of these options could be kept in mind for Moxlite V3 in a year or so's time?
I would like to compare L-R4 to B4 and unfortunately Moxlite might not let me do this thus prompting my questions. Sorry for the diatribe.

[Ed LaFontaine]

You lost me there....and I've returned from a fruitless search.

I got the Bx's = Butterworth
I got the L-Rx's = Linkwitz-riley

whadaya mean by MFB and EVS&K?