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Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Passive line-level BSC-compensation unit
Passive line-level BSC-compensation unit
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Old 4th December 2018, 08:40 AM   #1
lasser is offline lasser  Sweden
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Default Passive line-level BSC-compensation unit

Hello,

And sorry for being away for a while…

I am working on a passive 3-way speakersystem and realize that I need to add some BSC-compensation. Ihave tried to redesign the passive XO to do that but I think that a much smarter way to do this is by compensate at line level between pre- and poweramps.

One very trustworthy design would be the one described here:

Baffle Step Compensation

but the designer states that the output impedance from the preamp (in my case) should be less that 100 ohms and the input imp to the poweramp should be more than 20 kohms. The latter is no problems but my Citation 11 preamp has ”less than 500 ohms” according to the manual.

I wonder iif anyone of you electronics-cunning people can say if I can use the designed BSC-unit as-is or if there is a modification apparent to you that will take care of the difference in impedance of ”less than 500” to ”less than 100”

Best regards//lasse
Stockholm, Sweden
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Old 4th December 2018, 09:45 PM   #2
PRR is offline PRR  United States
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> use the designed BSC-unit as-is

Yes.

The <100r is very conservative and would only matter if you needed little-teeny correction. At any likely pot setting it is moot.
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Old 4th December 2018, 09:54 PM   #3
PRR is offline PRR  United States
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> my Citation 11 preamp has ”less than 500 ohms”

That's an oldie.

In fact it is likely to be nearer 10-20 Ohms (in series with 10uFd); I'd pencil "<50r" as a safe bet. The forward gain of the output stage is near 2,500, the set-gain is near 15, so 180:1 reduction of Zout. Naked Zout is near 2,800r, so that points to near 16 Ohms.
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Old 5th December 2018, 12:25 PM   #4
lasser is offline lasser  Sweden
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Quote:
Originally Posted by PRR View Post
> my Citation 11 preamp has ”less than 500 ohms”

That's an oldie.

In fact it is likely to be nearer 10-20 Ohms (in series with 10uFd); I'd pencil "<50r" as a safe bet. The forward gain of the output stage is near 2,500, the set-gain is near 15, so 180:1 reduction of Zout. Naked Zout is near 2,800r, so that points to near 16 Ohms.
Hi, forgive my ignorance but what will this mean for me?

Is it still OK to use the proposed design in my OP?

Yes, it´s a old amp but it, and its companion, Citation 12, is very dear and nostalgic to me. I spent the better part of my highschool years working and saving to buy them…..
(And now, they will have the company of a newly designed 3-way...)

Best regards//lasse
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