combine active xo and parametric eq

[tinitus]

anyone tried it ?

 

[tinitus]

ehh, the parametric would be a notch filter

on second thought, make it active xo, with 'reversed' graphic EQ, and optional parametric notch/peak filters

the 'reverse' trick
to use tweeter attenuation for the woofer low pass filters
and using a bass attenuation with the high pass filters

surely this must have been done before ?

 

[AndrewT]

The old Threads at
http://www.diyaudio.com/forums/anal...r-ii-gain-adjustment.html?highlight=crossover
or
http://www.diyaudio.com/forums/anal...nover-mox-like-setup.html?highlight=crossover
or
http://www.diyaudio.com/forums/analog-line-level/27651-mox-active-crossover.html?highlight=mox
or
http://www.diyaudio.com/forums/group-buys/53152-mox-active-crossover-buy.html?highlight=mox
or
http://www.diyaudio.com/forums/solid-state/36294-mox-builder-s-thread.html?highlight=mox

 

[tinitus]

a flexible active xo, I guess there's a first time for everything

is it because those who design the electronics have very little knowledge about speakers
and speaker designers, well.....

but with new digital technology, maybe a bit late for this
but i still intend to try a figure it out

 

[tinitus]

well, its been said before, there ain't no 12db Linkwitz Riley filter

12dB / Octave Linkwitz Riley Crossover

http://sound.westhost.com/project78.htm

I wonder how other 12db active LR filters look like

 

[tinitus]

hang on

ehh, Elliot use half his 3way 24db LR filter for the 12db LR project

maybe we could simple use the other half, so that each slope will have their own dedicated EQ

I'm in over my head here and think I better let this one go now

 

[tinitus]

I sent a note(mail) to ESP about this

 

[AndrewT]

Read the Linkwitz site for first hand information on the many EQs available for speaker crossovers and effects.

 

[tinitus]

yeah, I know its well described by Linkwitz
and wont hurt to read it again, and again
tho Im not very good at reading, and calculations even worse
Im not very well educated

Im looking at this schematic from ESP site, project 28
Parametric and Sub-Woofer Equaliser

and his project 09, crossover
Linkwitz-Riley Electronic Crossover

the same board is used for the 12db LR filter
they both look very similar to me

 

[tinitus]

well, I remember sometimes reading about active xo modules, they say may also be configured like ....

never thought much about it before, but now...?

 

[tinitus]

The low frequency section can be swept from 35Hz to 150Hz in peaking mode (this is the normal form of operation for a parametric equaliser), but also offers the option of shelving. Shelving is similar to the operation of conventional tone controls, but this is also sweepable, so the frequency can be changed to suit your requirements. Frequency increases as the 1M pots are reduced in value.

ehh, would this also be possible with the xo, making xo frequency 'sweepable' the same way ?

 

[AndrewT]

Yes, but !

the crossover requires quite precise matching of the roll off frequency and this matching becomes ever more critical as the roll off rate increases.

Switched sweeping could easily give the accuracy required for a 4pole crossover.
Ganged pots may only be any good for a single pole roll off, ie 6dB/oct or 20dB/dec

 

[tinitus]

Switched sweeping could easily give the accuracy.......

Ganged pots may only be any good for......

with ganged pots I take it you mean their possible inaccurate impedance

by switched I suppose you mean rotary switch mounted with resistors

 

[tinitus]

Yes, but !

the crossover requires quite precise matching of the roll off frequency and this matching becomes ever more critical as the roll off rate increases.

and acoustic slope

well, thats my major concern, and all the point of making it variable
and not just switching between fixed xo frequencies

are we talking about the same thing, or ?

 

[AndrewT]

The EQ corrects for the anomalies of the driver output. The crossover filter rolls off the corrected driver response. You don't need to sweep the EQ, just sweep the crossover filter.

The crossover filters meet in the middle. That middle point is quite precisely defined. If you want to move it to a new frequency, then both filters need to be moved exactly the same amount.
You can't do that with a 2 gang, nor a 4 gang pot.
You can do it accurately with a 2 wafer, or 4 wafer switch

 

[tinitus]

The crossover filters meet in the middle. That middle point is quite precisely defined. If you want to move it to a new frequency, then both filters need to be moved exactly the same amount.

yes, thats how it usually is
and it will work
but can never be optimal

not to offend you Andrew, but Im not sure you understand what Im saying, or asking
how much do you know about speaker design ?

btw, it is the only reason why a digital DSP makes any sense at all
but I still do my best to avoid it

 

[tinitus]

oh, btw, I have been in contact with Rod Elliot

obviously noone seem to have a clew what Im talking about, or why
Im surpriced
or maybe not
or my english is simply very poor

a flexible active xo, I guess there's a first time for everything

is it because those who design the electronics have very little knowledge about speakers
and speaker designers, well.....

well, maybe I will get over it, and stick to my usual passive crossovers

 

[joexswj]

i think that's just for fixed crossover,
like HiFi Amplifier.

 

[tinitus]

i think that's just for fixed crossover,

I cannot believe fixed xo points work well with any speaker units



well, I do know its 'immune' to the usual issues with varying impedance
which is a real big issue with passive xo
but it still does not deal with frequency changes
with all properly designed passive crossovers, the acoustic slopes have top priority
but obviously not so with active xo

 

[AndrewT]

Which bits of speaker design do you want/need me to confirm that I know next to nothing about?

Make a list and I will tick off all the bits I do know a little about. I can assure I will not be able to tick off that many, but that does not help you in any way. Just accept the advice and decide what you want to believe (sorting the wheat from the chaff).