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Old 8th November 2011, 02:46 PM   #1
pjanda1 is offline pjanda1  United States
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Default Sure TA2024 + speaker level plate amp?

Is there a problem summing the speaker neg terminals on a Sure TA2024 board? I recall that this was an issue connecting plate amps to the old Sonic Impact, but also that some claimed it worked fine. I'm thinking of giving my brother-in-law a sub to connect at speaker level, but I don't have the Sure amp in front of me to play with and I want to be sure it will work. I must be using the wrong search terms to find the answer. . .

Paul
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Old 8th November 2011, 05:42 PM   #2
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Is there a problem summing the speaker neg terminals on a Sure TA2024 board?
You will fry the amp instantly.
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Old 8th November 2011, 05:56 PM   #3
pjanda1 is offline pjanda1  United States
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Its possible to make it work with a resistor network isn't it? I've read many references to "Ed's Magic Box" (Ed of the Horn Shoppe), but I have yet to dig up a schematic.

Paul
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Old 8th November 2011, 08:23 PM   #4
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Its possible to make it work with a resistor network isn't it?
No
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Old 8th November 2011, 09:25 PM   #5
pjanda1 is offline pjanda1  United States
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Sooo, whats inside the "Magic Cable?"? Plenty of folks are using it to connect TA2024s to plate amps. I know some schematics used to exist over on Audio Circle, but I'm having a hard time digging them up.

Paul
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Old 8th November 2011, 09:41 PM   #6
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There's something you're not reading correctly here.

The "magic cable" talk about the amp input. Can you use a resistor network here? Sure.

You were asking if you could sum the negative outputs, essentially bridging the amp, and whether you could do that? Under no circumstances can you bridge an already bridged amp, it will be fried instantly!
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Old 8th November 2011, 10:19 PM   #7
pjanda1 is offline pjanda1  United States
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The magic cable runs from the speaker level outputs of the T-amp (they use them with the Sonic Impact version of the TA2024) to the RCA inputs of the plate amp, which have a common ground! Somehow or another, dozens of folks are connecting both negative terminals of a TA2024 to a common ground with nothing active in between. (SI amps are common amongst the Horn Shoppe crowd, and I think you can even see a pic of one driving a plate amp at audio circle). Maybe I should just email Ed, but he's a cantankerous fellow.

Paul
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Old 9th November 2011, 02:50 AM   #8
wwenze is offline wwenze  Singapore
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Instead of calling them "negative" terminals, call them "inverted outputs". It becomes clearer what you can do and not do with them.
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Old 9th November 2011, 03:00 AM   #9
pjanda1 is offline pjanda1  United States
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True. How about "black outputs"

Paul
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Old 10th November 2011, 03:17 AM   #10
pjanda1 is offline pjanda1  United States
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I emailed Ed to ask about the guts of the "magic cable", Here is his reply:

Quote:
Paul, There was a 20k resistor in line with each "positive" and one negative had a 10k resistor in series with the ground. this gave enough isolation in most cases. You can also just put a 20-50k in series with both positives and leave one of the channels negative unconnected. This usually works fine too. The problem is the grounds can not be connected together directly.
Hope this helps.
Paul
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