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Old 13th May 2011, 06:14 PM   #1
NYCOne is offline NYCOne  United States
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Default Not a new idea, but some questions on an old one

I'm increasingly interested in putting the toroid(s) and caps in a separate enclosure and only having the Amp PCBs in a heat-sinked enclosure - making three boxes for an amp, two PS and one output.

It strikes me that one can gain a lot of advantage with this configuration in terms of electrical noise, cost of the heat-sinked enclosure (it can be a smaller box with the same sinks). One can go true mono for the PS and marry the amp in the sinked enclosure.

The questions:

What are common pitfalls of such a setup?
What wire and connectors have folks found useful for the PS to sinked box connections?
Do you lose the benefit of a mono set up if you have both output channels in the same box?
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Old 13th May 2011, 08:02 PM   #2
qusp is offline qusp  Australia
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haha again man, what is it with us having the same ideas. i was just thinking about this yesterday when pondering transformers, as i'm biamping with digi xo and it would seem to make sense to me to locate both tx and probably half the supply caps with the other half of the filtering in the amp cases.

comes from my background in headphone amps and such i guess and seems appropriate here. except i'm looking at one large ps enclosure with 2 x 500va and 1 x 800va plus bridges, softstart and crc, then crc in each separate amp case. even considering having one channel from each amp (aleph jx and semisouth circ for now till f5x is ready) in each case and that way locating each near the speaker with the separate 'balanced' output tweeter and midbass channels feeding left and right respectively, with a central psu case and heavy duty umbilicals

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Old 13th May 2011, 08:08 PM   #3
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Old 13th May 2011, 08:23 PM   #4
qusp is offline qusp  Australia
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yeah speakons, or i actually prefer the amphenol 5W5 or 8W8 hybrid dsub with 5 or 8 pins respectively. i've used them for fast charging lifepo4 batteries at much higher currents than they'll see here

Click the image to open in full size.

6awg copper pins

Click the image to open in full size.

will possibly end up using one of the mixed high current and 2amp pin versions with a number of pins for auxiliary powered stuff like leds and momentary switches etc. can even get them with shielded coax pins for those

Last edited by qusp; 13th May 2011 at 08:29 PM.
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Old 13th May 2011, 09:05 PM   #5
NYCOne is offline NYCOne  United States
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The issue for me is all the great, large caps I have. I have 68,000uF 70V that are 6" high, and I'm getting 120,000uF 40V that are 9" high. I need a way to use these without redoing my cases from scratch.

An external CRC seems like the way to go. Pipe the DC into the PCB and heatsink box and you havde huge, clean, shielded power with a small(ish) output box.
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Old 13th May 2011, 09:34 PM   #6
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yes, but probably you will still want some sort of local smoothing/reservoir, or those big caps and their low esr will be for nought
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Old 13th May 2011, 09:45 PM   #7
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You could have the transformer, bridge, and first part of CRC in one PS box, and then some more C plus amp in another main box. Didn't NP suggest this (to keep the transformer separate) many years ago in an article?

One consideration is choosing and laying out the heat sinks for best cooling and also considering placing it higher up (off the floor) in the 'rack' where cooling is better naturally. But big class A amps mean big heat sinks, which constrains the styling a lot....

I don't even want to open the can of worms debate on stereo v monoblocs, but I prefer fewer boxes....

Last edited by Andersonix; 13th May 2011 at 09:51 PM.
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Old 13th May 2011, 09:47 PM   #8
NYCOne is offline NYCOne  United States
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Quote:
Originally Posted by qusp View Post
yes, but probably you will still want some sort of local smoothing/reservoir, or those big caps and their low esr will be for nought
Not sure what you mean here. I was thinking CRC. Are you talking about something else?

Maybe the "R" could be part of the cable and the other C in the box as suggested above?
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Old 13th May 2011, 10:41 PM   #9
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I have thought of this arrangement as well. I would like the power supply located near an outlet and the circuits near the speakers. One concern I have is grounding. In this configuration, would there be more of a problem with ground loops, not having everything in one grounded chassis?

slug
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Old 13th May 2011, 10:48 PM   #10
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I have thought of this arrangement as well. I would like the power supply located near an outlet and the circuits near the speakers. One concern I have is grounding. In this configuration, would there be more of a problem with ground loops, not having everything in one grounded chassis?

slug
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