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Old 28th May 2012, 12:32 AM   #11
tinitus is offline tinitus  Europe
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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 ?
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Old 28th May 2012, 11:17 AM   #12
AndrewT is offline AndrewT  Scotland
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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
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Old 28th May 2012, 01:46 PM   #13
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by AndrewT View Post

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
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Old 28th May 2012, 08:43 PM   #14
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by AndrewT View Post
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 ?
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Old 28th May 2012, 09:40 PM   #15
AndrewT is offline AndrewT  Scotland
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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
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Old 28th May 2012, 10:53 PM   #16
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by AndrewT View Post

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
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Old 29th May 2012, 01:34 AM   #17
tinitus is offline tinitus  Europe
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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

Quote:
Originally Posted by tinitus View Post
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
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Old 29th May 2012, 08:40 AM   #18
joexswj is offline joexswj  Indonesia
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i think that's just for fixed crossover,
like HiFi Amplifier.
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Old 29th May 2012, 09:59 AM   #19
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by joexswj View Post
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
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Old 29th May 2012, 10:32 AM   #20
AndrewT is offline AndrewT  Scotland
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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).
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