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Old 13th March 2013, 08:10 PM   #811
Congo5 is offline Congo5  United States
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Quote:
Originally Posted by bcmbob View Post
Congo5, Do you have any photos of your setup for the ACAs with earphones? Are you using a balanced set/converter?
I do not have any thing balenced... amps, Sources, or Phones.


Since the ACA is an inverting amp, the outputs marked + are common between channels.
So that becomes headphone common or -
the – out are used for R and L out.


This could be connected to your board or binding posts.
A DPDT Switch between speakers/headphone jack would be nice.

Yes the signal to my phones is inverted but neither my head nor the phones seem to mind.
I hope that is clear ?
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Old 13th March 2013, 11:43 PM   #812
bcmbob is offline bcmbob  United States
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How's this ? Corrections welcomed
Attached Images
File Type: jpg ACA Phone Dia.jpg (181.2 KB, 601 views)
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Last edited by bcmbob; 13th March 2013 at 11:45 PM.
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Old 14th March 2013, 12:08 AM   #813
Congo5 is offline Congo5  United States
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yup that looks right.
on the schematic the + outputs are connected to power supply ground so I reversed the colors and
used red for board out -
and black for out +
but colors don't matter as electrons are color blind
your red will still be speaker + on your drawing

on the headphone jack the tip is left channel
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Old 14th March 2013, 12:11 AM   #814
bcmbob is offline bcmbob  United States
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Thanks, I'll do a revision and post later.
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Old 14th March 2013, 12:30 AM   #815
Congo5 is offline Congo5  United States
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no, I like your colors, just explaining what I did.....
yours makes perfect sense....
I don't have any good pic's but here is what I do have.
built this for a friend after he heard mine...
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File Type: jpg jj-aca.jpg (105.5 KB, 583 views)
File Type: jpg jj-aca1.jpg (114.0 KB, 561 views)
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Old 14th March 2013, 12:33 AM   #816
bcmbob is offline bcmbob  United States
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Simple enough - I'll do a setup this weekend and report back.

Thanks Again.
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Old 18th March 2013, 02:16 AM   #817
xrk971 is online now xrk971  United States
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Default h_fg (heat of vaporization) of water as heat sink

I am new here in this forum so this may be a stupid question. Has anyone considered using the heat of vaporization (h_fg in thermodynamics parlance) of water as a heat sink for hot burning class-A amps? Water is able to remove huge amounts of heat as a substance for heat transfer, it is almost without equal. I am not talking about sensible heat capacity like in a liquid flow heat exchanger but something really simple - a pot of water.

I am considering building the Amp Camp Amp and want to keep this low budget. I can handle the parts from Digikey for $15. What I don't like are the costs of large aluminum heat sinks or fancy enclosures.

I have an old aluminum cookpot that my wife wants to throw away because the non-stick coating is peeling off. I was thinking why not mount the 4 mosfets to the sides, add some water before you start listening, and let the watts start to evaporate the water to cool the transistors? It won't boil because there is not enough heat to overcome the heat of vaporization and radiative losses. But it will get mildly warm. I think a gallon of water will take a long time for those mosfets to cook off.

The heat of vap of water is 540 cal/g or 2257 J/g. Assuming the mosfets dissipate 100 watts or 100 J/sec. This means that you get 23 seconds of run time per gram of water. Let's say you fill the pot with 2 liters of water or 2000 grams before running it. 23 sec/g x 2000 g = 46000 sec or 12.8 hours. Maybe add a thermal shutdown or light timer to turn your SMPS off after 8 hrs in case you forget...

Sure it looks kind of wierd to have your mosfets on a pot of water that can splash. But there are ways around this.
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Old 18th March 2013, 03:19 AM   #818
6L6 is offline 6L6  United States
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I re-read your post more carefully.

I like it!!
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Old 18th March 2013, 04:01 AM   #819
Variac is offline Variac  United States
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Yup, water's amazing stuff. Your approach should be just fine for most listening sessions.Just that it requires "topping up" which these days people don't want to bother with.

Think about this- when water freezes it floats.... it's less dense.
Normally frozen things aren't .

Lucky, because otherwise frozen water would sink and the oceans would eventually be solid ice.
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Old 18th March 2013, 04:27 AM   #820
xrk971 is online now xrk971  United States
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Another benefit is that you can use this water to make tea while you listen to your music

OK, so not such a stupid crazy idea after all?
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