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Old 18th January 2007, 08:35 PM   #1
skogs is offline skogs  Norway
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Default Linkwitz Transform curcuit.

Hi.
Im going to make a LTC for my SW. But what is the difference between ESP's version and the original LTC spreadsheet version? In the latter there's not included any additional power supplys. what is the point of using this, as shown in esp's version?

The only difference that i can see is that one doesn't have to worry about the DC gain exceeding 20db.
I don't need inverter or mixer curcuit.

http://sound.westhost.com/project71.htm
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Old 18th January 2007, 08:59 PM   #2
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ESP's Linkwitz Transform and the 'original LT' are one and the same. You need to worry about gain in all cases.
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Old 18th January 2007, 09:02 PM   #3
skogs is offline skogs  Norway
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Quote:
Originally posted by richie00boy
ESP's Linkwitz Transform and the 'original LT' are one and the same. You need to worry about gain in all cases.
but on esp's curcuit is it included a power supply. the -15 and +15 thing. and that's not included on the spreadsheet curcuit! So, do i need a power supply, or can i just make the curcuit sketched on the spreadsheet and connect it directly between the main amp and the sub amp?
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Old 19th January 2007, 12:10 AM   #4
infinia is offline infinia  United States
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All active circuits require a power supply. Some are not shown for the fact of simplifing things. Also supply pins need decoupling capacitors located close to the actual pins, these are almost universally for audio 0.1uF ceramic or film types.
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Old 19th January 2007, 12:32 AM   #5
infinia is offline infinia  United States
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Default Re: Linkwitz Transform curcuit.

Quote:
Originally posted by skogs
Hi.

The only difference that i can see is that one doesn't have to worry about the DC gain exceeding 20db.
I don't need inverter or mixer curcuit.

http://sound.westhost.com/project71.htm

You need to use an added inversion stage, but also can reverse the leads of the woofer to PA in a pinch. I see danger/ cautioning past 10 dB of gain, but YMMV.
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Old 19th January 2007, 04:25 PM   #6
skogs is offline skogs  Norway
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so if i have a phase switch on my already, all i need is the "Figure 2 - Linkwitz Transform Circuit" on esp and a 15V trafo to get an complete LT? i don't need signal summer as i will get the signal from the sw-output on my main amp.
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Old 19th January 2007, 05:28 PM   #7
bibster is offline bibster  France
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You'll need some symmetric 15V power supply....
that is: PLUS 15v, Zero, and MINUS 15v....

You might use a +30V PS, and sort of divide it in two, and create a floating GND by means of a simple resistor based voltage divider... (It's all on the sound.westhost site...: http://sound.westhost.com/project43.htm )

Cheers, Paul
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Old 19th January 2007, 08:15 PM   #8
infinia is offline infinia  United States
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Quote:
Originally posted by skogs
so if i have a phase switch on my already, all i need is the "Figure 2 - Linkwitz Transform Circuit" on esp and a 15V trafo to get an complete LT? i don't need signal summer as i will get the signal from the sw-output on my main amp.
Ahh it seems you are going into a powered Sub then... you need 180 deg from zero Hz (inversion)... phase adjust switches don't do that. Besides the useless "phase switch" most sub amps have built in filters for bass boosting. So you need to bypass those functions as well if there is any hope of success here.
Just order a LT PCB and a dual power supply PCB from the ESP site or copy his designs exactly. If you want ( if you are technically comfortable) you could rewire inside the amp to use their opamp supply while you defeat the standard built in filter.
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