finding positive output lead from preamp

skogs · 7th October 2007, 06:58 PM

Hi. ive just purchased a new pa-amp to drive two of my subs. i want to use the preamp from my subwoofer-plateamp. so now i have opened the plate-amp and found the +\- 15V leads to drive the equaliser, rumble filter and individual phase controls im making. and i have found what i belive is the postive lead (one of the leads i will use the connect the pa-amp, the one that connects the preamp and "main" amp), but how can i measure that without breaking anything?
could i send for example a 100hz signal into the input on the preamp, and measure the currency between the lead i think is the ouput lead and the ground?

unclejed613 · 8th October 2007, 10:37 PM

it would be simpler to build a +/- 15v supply for the signal processing. all you need is a 20-0-20V 1A transformer, a small bridge rectifier, 2 4700uf/35V caps and a LM7815/7915 pair. for a few junkbox components you can have clean power for your sub processor.

7th October 2007, 06:58 PM	#1
skogs diyAudio Member Join Date: Oct 2006	finding positive output lead from preamp Hi. ive just purchased a new pa-amp to drive two of my subs. i want to use the preamp from my subwoofer-plateamp. so now i have opened the plate-amp and found the +\- 15V leads to drive the equaliser, rumble filter and individual phase controls im making. and i have found what i belive is the postive lead (one of the leads i will use the connect the pa-amp, the one that connects the preamp and "main" amp), but how can i measure that without breaking anything? could i send for example a 100hz signal into the input on the preamp, and measure the currency between the lead i think is the ouput lead and the ground?

8th October 2007, 10:37 PM	#2
unclejed613 diyAudio Member Join Date: Dec 2006	it would be simpler to build a +/- 15v supply for the signal processing. all you need is a 20-0-20V 1A transformer, a small bridge rectifier, 2 4700uf/35V caps and a LM7815/7915 pair. for a few junkbox components you can have clean power for your sub processor. __________________ Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net spammer trap: http://www1284177414881.v-dc.net/

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