Leach Amp Sub Pre-out

jrhgohawks · 26th June 2005, 07:38 PM

I am finishing up a leach amp and I was thinking of adding a sub-pre out. I am pretty new to all of this and I was wondering how to do it. I assumed I would just tap off of one my volume controlled input lines and throw it through a LPF. Any thoughts would be greatly appreciated.

Thanks

Justin

viktor1986 · 26th June 2005, 10:19 PM

Built this
You must have preamp

jrhgohawks · 24th August 2005, 07:43 PM

I am a little new to the DIY Audio realm so I apologize for my naivete. I just built a two channel Leach amp but I want to add a subwoofer preout, not a preamp. I wish to hook them up to my existing speakers/subs. Is a sub preout simply an LPF or even simpler an input tap? I have looked for documentation but haven’t been able to find anything. Also, if it is just and LPF does anyone have one that can accommodate the 60V+ rails of the Leach amp?

BobEllis · 24th August 2005, 08:52 PM

To do it "right" you'll need something like what Viktor showed - it is an active crossover that sends the top end to your leach and provides a separate output for your sub.

You may be able to get away with a Y cable if thesubwoofer amp has a built in crossover that will allow it to mate properly with your main speakers. Suppose that your mains are ported and have an F3 of 50 Hz. If the subwoofer amp XO is fourth order and allows XO frequencies below 50 Hz, it may work, but a proper active XO that takes the response of the mains into account will probably sound better.

jrhgohawks · 25th August 2005, 03:59 PM

Ok sounds good. I will build it. I didn't realize exactly what it was before. I did have a couple of questions about the schematic though. What are the 1k5, 3k9, 1M2, and 82E resistors on the schematic? Are they supposed to be 15k and 39k? But what about the others? Also can I get away with just 1/4 watt for these? Finally, any one have suggestions for good selector switches?

Thanks,
Justin

tobias_svensk · 25th August 2005, 05:08 PM

1k5 = 1.5k
3k9 = 3.9k
1M2 = 1.2M
82E = 82
I think you get it now

jrhgohawks · 25th August 2005, 05:48 PM

Thanks, I do. Sorry I wasn't familiar with that particular notation.

I'm only used to my version of Pspice.

Any thoughts on the switches?

26th June 2005, 07:38 PM	#1
jrhgohawks diyAudio Member Join Date: Nov 2004 Location: Illinois	Leach Amp Sub Pre-out I am finishing up a leach amp and I was thinking of adding a sub-pre out. I am pretty new to all of this and I was wondering how to do it. I assumed I would just tap off of one my volume controlled input lines and throw it through a LPF. Any thoughts would be greatly appreciated. Thanks Justin __________________ Justin

24th August 2005, 07:43 PM	#3
jrhgohawks diyAudio Member Join Date: Nov 2004 Location: Illinois	I am a little new to the DIY Audio realm so I apologize for my naivete. I just built a two channel Leach amp but I want to add a subwoofer preout, not a preamp. I wish to hook them up to my existing speakers/subs. Is a sub preout simply an LPF or even simpler an input tap? I have looked for documentation but haven’t been able to find anything. Also, if it is just and LPF does anyone have one that can accommodate the 60V+ rails of the Leach amp? __________________ Justin

25th August 2005, 03:59 PM	#5
jrhgohawks diyAudio Member Join Date: Nov 2004 Location: Illinois	Ok sounds good. I will build it. I didn't realize exactly what it was before. I did have a couple of questions about the schematic though. What are the 1k5, 3k9, 1M2, and 82E resistors on the schematic? Are they supposed to be 15k and 39k? But what about the others? Also can I get away with just 1/4 watt for these? Finally, any one have suggestions for good selector switches? Thanks, Justin __________________ Justin

25th August 2005, 05:48 PM	#7
jrhgohawks diyAudio Member Join Date: Nov 2004 Location: Illinois	Thanks, I do. Sorry I wasn't familiar with that particular notation. I'm only used to my version of Pspice. Any thoughts on the switches? __________________ Justin

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24th August 2005, 08:52 PM	#4
BobEllis diyAudio Member Join Date: Sep 2003 Location: Upstate NY	To do it "right" you'll need something like what Viktor showed - it is an active crossover that sends the top end to your leach and provides a separate output for your sub. You may be able to get away with a Y cable if thesubwoofer amp has a built in crossover that will allow it to mate properly with your main speakers. Suppose that your mains are ported and have an F3 of 50 Hz. If the subwoofer amp XO is fourth order and allows XO frequencies below 50 Hz, it may work, but a proper active XO that takes the response of the mains into account will probably sound better.

25th August 2005, 05:08 PM	#6
tobias_svensk diyAudio Member Join Date: Jan 2004 Location: Hudiksvall	1k5 = 1.5k 3k9 = 3.9k 1M2 = 1.2M 82E = 82 I think you get it now

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