I've got these custom made active XOs that are 2 way 24LR with an overall system HP at 15Hz LR4 to protect subsonics. They have 3 different XO points selectable by the dip switches. Currently I intend to try 100, 300 and 500. Or near enough as my resistances got me to. It is SE input, thru the LR24 filters and then buffered into the signal trafos that do SE> balanced. Quite nice things that I hope work well for me.
I want to try adding a Linkwitz transform to the LF section...see if my amps and woofers can handle it!
I guess I need to put the LT after this LR24 but I wasnt sure about the balanced output of the trafos into an SE LT PCB. I'm sending the LF section of this XO into mono 3255s that accept a B input so would be a shame to lose that.
So can I do the LT on the 'entire' signal before the active XOs when I'm all still in SE? I didn't know about sending a boosted LF signal thru the trafos.
Thanks
I want to try adding a Linkwitz transform to the LF section...see if my amps and woofers can handle it!
I guess I need to put the LT after this LR24 but I wasnt sure about the balanced output of the trafos into an SE LT PCB. I'm sending the LF section of this XO into mono 3255s that accept a B input so would be a shame to lose that.
So can I do the LT on the 'entire' signal before the active XOs when I'm all still in SE? I didn't know about sending a boosted LF signal thru the trafos.
Thanks
Hi,
Better place LT post Xover: you'll compromise system headroom if located before xover. Like you i would be concerned about transformer that could be overloaded by boost in low end. That said it'll depend of the transfo itself, some perform very well ( but are $$$).
Having them at output guarantee galvanic isolation so it's a nice feature to isolate from noise on line though.
Balanced/unbalanced ( SE describe a circuit, not connection type):
Your LT transform circuit will very probably have an unbalanced in/out.
Transformers accept to receive/drive both type ( unbalanced/balanced) so it shouldn't be an issue at input of LT circuit ( keep cable length short if unbalanced).
That said if you are more confortable using balanced then use line driver/receiver like THAT 1246/1646 combo at in/out of your LT circuit and you are done.
Those are transparent ( from audio pov) and mimic transformer behavior.
Better place LT post Xover: you'll compromise system headroom if located before xover. Like you i would be concerned about transformer that could be overloaded by boost in low end. That said it'll depend of the transfo itself, some perform very well ( but are $$$).
Having them at output guarantee galvanic isolation so it's a nice feature to isolate from noise on line though.
Balanced/unbalanced ( SE describe a circuit, not connection type):
Your LT transform circuit will very probably have an unbalanced in/out.
Transformers accept to receive/drive both type ( unbalanced/balanced) so it shouldn't be an issue at input of LT circuit ( keep cable length short if unbalanced).
That said if you are more confortable using balanced then use line driver/receiver like THAT 1246/1646 combo at in/out of your LT circuit and you are done.
Those are transparent ( from audio pov) and mimic transformer behavior.
About Single Ended, Push Pull, Balanced and Unbalanced:
Single Ended and Push Pull describe topology of circuit used. It is related to symmetry (or not) used within circuit. It can be push pull, differential,single ended,...
Balanced is a shortcut for Balanced impedance ( to ground) line. Unbalanced for Unbalanced impedance line.
It's easy to make a link between PP/differential and Balanced: after all both use a +/- connection so they should be the same thing no?... but Balanced refer to impedance and not to a symmetrical signal drive: it's about common mode impedance and thus noise attenuation along the line. So balanced line are a whole different thing than symmetrical drive.
In pro audio we can see assymetrical drive on xlr connected to pin 2 (hot/+) and a resistor to ground on pin 3(cold/-) and ground on pin 1. At first look it looks like unbalanced but it's not as the resistor value ( on pin 3 cold/-) equal impedance on hot, thus making a balanced impedance... this kind of arrangement is known as 'quasi balanced' iirc and is part of the balanced impedance family ( but with an asymetrical drive signal)... this can be misleading and the fact we use shortcut like balanced/unbalanced without being more accurate about what it refers to add to confusion.
If you want to dig deeper this is worth a read:
https://sound-au.com/articles/balanced-2.htm
Single Ended and Push Pull describe topology of circuit used. It is related to symmetry (or not) used within circuit. It can be push pull, differential,single ended,...
Balanced is a shortcut for Balanced impedance ( to ground) line. Unbalanced for Unbalanced impedance line.
It's easy to make a link between PP/differential and Balanced: after all both use a +/- connection so they should be the same thing no?... but Balanced refer to impedance and not to a symmetrical signal drive: it's about common mode impedance and thus noise attenuation along the line. So balanced line are a whole different thing than symmetrical drive.
In pro audio we can see assymetrical drive on xlr connected to pin 2 (hot/+) and a resistor to ground on pin 3(cold/-) and ground on pin 1. At first look it looks like unbalanced but it's not as the resistor value ( on pin 3 cold/-) equal impedance on hot, thus making a balanced impedance... this kind of arrangement is known as 'quasi balanced' iirc and is part of the balanced impedance family ( but with an asymetrical drive signal)... this can be misleading and the fact we use shortcut like balanced/unbalanced without being more accurate about what it refers to add to confusion.
If you want to dig deeper this is worth a read:
https://sound-au.com/articles/balanced-2.htm
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Yes B. Whitlock is the brain behind transformers design at Jensens and is the designer of the THAT driver/receiver chips. He is close to be 'the last word' on the subject.
You probably don't need to read the full article, introduction contain most of the useful info.
And truth have to be told: even in pro engineering the principle of balanced impedance is not well known, most people think it relates to symmetry drive signal and does not know about common mode rejection.
Neither do they know why transformers are used from a technical pov ( except basic and the fact when used gear have 'nice' sound).
If you are not into circuit design and maintenance it's not widespread knowledge. Sadly.
You probably don't need to read the full article, introduction contain most of the useful info.
And truth have to be told: even in pro engineering the principle of balanced impedance is not well known, most people think it relates to symmetry drive signal and does not know about common mode rejection.
Neither do they know why transformers are used from a technical pov ( except basic and the fact when used gear have 'nice' sound).
If you are not into circuit design and maintenance it's not widespread knowledge. Sadly.
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