Opinions on a multi channel Amp.

keyboard123 · 8th February 2011, 05:15 PM

i'm planning to put together a 6 channel amp using audiosector kits, the LM3875 for the high and mid each one, and a LM4780 for the Bass. the all have separate transformers. Little heavy.

what are the pros and cons of having the amps placed near the source as against having them near the speakers. Apart from speaker cable size and cost,
what would the electrical nuances? Like noise, balance etc. be?
My audio source SPDIF is going to feed my DSP box consisting of miniDSP and multichannel DAC's , (fed by miniDIGI's via SPDIF. ) to the Amps.

Will it be long speaker cables or long signal cables. ?!

ianpengelly · 9th February 2011, 07:13 PM

Long signal cables tends to be the recommendation as the losses are lower than at speaker level. However, depending on your cable runs and what they are running near, they could be more prone to picking up noise than speaker cables. What distance is going to be between your source and your speakers?

keyboard123 · 9th February 2011, 10:57 PM

Thanks Ian,
From source to speakers, about 3- 4 meters. I'm leaning towards having the amps near the speakers.

ianpengelly · 10th February 2011, 05:32 AM

Over that sort of distance it probably isn't a massive issue, especially as you would require multiple runs for and active set up. However, going the line level to the speaker locations would possibly be neater. Best of luck!

abraxalito · 10th February 2011, 05:42 AM

Having so many separate transformers isn't such a brilliant idea. Not only is it more expensive, more wiring its also worse from the pov of more noise coming off the mains supply due to all the transformer capacitances to mains.

One of the issues to consider is ease of switching the things off - if you have one set of amps at each speaker, do you want to run both on a dedicated extension cord so you can power them both down with a single switch? Such a cord trailing across your room might be a bit of a pain. Having all the amps inside one box has the convenience of just one switch. If it were me I'd have 3m long speaker cables using Cat6 (very cheap). Two cables (paralleled 8 twisted pairs) for the woofer, one each for the mid and tweeter. The wiring then is just point to point.

keyboard123 · 10th February 2011, 11:43 PM

Thanks for the input guys,
I plan to build them in two chassis. One for each speaker.
i might try both possibilities. Long signal wires or speaker wires , thinking of it. Sonically only trying it will tell.

AndrewT · 11th February 2011, 10:26 AM

I very much favour amp next to speaker.
That is very short speaker cables and longish interconnects for the line level signals.
Ensure your source can drive the interconnects. You may need to add a buffer to each output of your source.

keyboard123 · 11th February 2011, 08:22 PM

Thank You. Noted.

MJL21193 · 11th February 2011, 09:30 PM

Quote:

Originally Posted by abraxalito

Having so many separate transformers isn't such a brilliant idea.

That is a point worth repeating.

Building 2 separate units seems like a good idea until you actually do it. I have done it both ways and I can say that a single unit with all of the amps inside is the better way.

MJL21193 · 11th February 2011, 09:32 PM

Quote:

Originally Posted by AndrewT

I very much favour amp next to speaker.

You keep saying this but I'll be damned if I can figure out why...you are usually a more sensible fellow

8th February 2011, 05:15 PM	#1
keyboard123 diyAudio Member Join Date: Mar 2009 Location: Brampton,ON.	Opinions on a multi channel Amp. i'm planning to put together a 6 channel amp using audiosector kits, the LM3875 for the high and mid each one, and a LM4780 for the Bass. the all have separate transformers. Little heavy. what are the pros and cons of having the amps placed near the source as against having them near the speakers. Apart from speaker cable size and cost, what would the electrical nuances? Like noise, balance etc. be? My audio source SPDIF is going to feed my DSP box consisting of miniDSP and multichannel DAC's , (fed by miniDIGI's via SPDIF. ) to the Amps. Will it be long speaker cables or long signal cables. ?!

10th February 2011, 05:42 AM	#5
abraxalito diyAudio Member Join Date: Sep 2007 Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though... Blog Entries: 62	Having so many separate transformers isn't such a brilliant idea. Not only is it more expensive, more wiring its also worse from the pov of more noise coming off the mains supply due to all the transformer capacitances to mains. One of the issues to consider is ease of switching the things off - if you have one set of amps at each speaker, do you want to run both on a dedicated extension cord so you can power them both down with a single switch? Such a cord trailing across your room might be a bit of a pain. Having all the amps inside one box has the convenience of just one switch. If it were me I'd have 3m long speaker cables using Cat6 (very cheap). Two cables (paralleled 8 twisted pairs) for the woofer, one each for the mid and tweeter. The wiring then is just point to point. __________________ When a measure becomes a target, it ceases to be a good measure. C.A.E. Goodhart

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9th February 2011, 07:13 PM	#2
ianpengelly diyAudio Member Join Date: Oct 2006	Long signal cables tends to be the recommendation as the losses are lower than at speaker level. However, depending on your cable runs and what they are running near, they could be more prone to picking up noise than speaker cables. What distance is going to be between your source and your speakers?

9th February 2011, 10:57 PM	#3
keyboard123 diyAudio Member Join Date: Mar 2009 Location: Brampton,ON.	Thanks Ian, From source to speakers, about 3- 4 meters. I'm leaning towards having the amps near the speakers.

10th February 2011, 05:32 AM	#4
ianpengelly diyAudio Member Join Date: Oct 2006	Over that sort of distance it probably isn't a massive issue, especially as you would require multiple runs for and active set up. However, going the line level to the speaker locations would possibly be neater. Best of luck!

10th February 2011, 11:43 PM	#6
keyboard123 diyAudio Member Join Date: Mar 2009 Location: Brampton,ON.	Thanks for the input guys, I plan to build them in two chassis. One for each speaker. i might try both possibilities. Long signal wires or speaker wires , thinking of it. Sonically only trying it will tell.

11th February 2011, 10:26 AM	#7
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	I very much favour amp next to speaker. That is very short speaker cables and longish interconnects for the line level signals. Ensure your source can drive the interconnects. You may need to add a buffer to each output of your source.

11th February 2011, 08:22 PM	#8
keyboard123 diyAudio Member Join Date: Mar 2009 Location: Brampton,ON.	Thank You. Noted.