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# Pyramid-shaped, water-cooled, floor-lamp B22/Buffalo-II concept - Page 3

Quote:
Originally Posted by haveblue
A remote controlled volume pot and LCD is a neat idea though. I'll look into that. But doesn't that defeat the purpose of not having any motors whatsoever in the case?

That's not what he suggested.  He said a relay based control.

Subscribed! This thread is epic is this works out!

How about we avoid water all together and go with oil immersion cooling?

http://www.maximumpc.com/article/features/hardcorepc_reactor?page=0,0

http://www.pugetsystems.com/aquarium-computer.php

Edited by francisdemarte - 10/27/10 at 3:25pm

This is a common misconception. The only reason you don't see full copper heatsinks is due to weight and cost. Given an identical heatsink shape and size, a full copper heatsink will absorb and dissipate heat better than aluminum.

for the most relevant part:

Quote:

OK, specific heat (Cp) is the measure of how much energy it takes to raise the temperature of 1kg of material 1degree (C or K). The Cp for copper is 385 Joules/kg*K and for aluminum is 903 J/kg*K (at 300K = 23 deg. C). density for both is copper: 8933 kg/m^3 and alum: 2702 kg/m^3

So, if we have two same SIZED blocks of material, say 1m x 1m x 1m for simplicity, we have different masses, namely 2700kg of alum. and 8930 kg Cu. if we put 2.438 x 10^6 Joules of energy into each block, we can calculate the temp raise:

Q = m*Cp*deltaT --> deltT = Q/(m*Cp)

deltaT alum: = 2.4381 x 10^6 J/(2700 kg * 903 J/kg*K) =1 degree

deltaT Cu: = 2.4381 x 10^6 J /(8933 kg * 385 J/kg*K) = 0.71 degree

so for the same SIZE blocks, more heat is energy is required to heat the copper by the same delta T than the aluminum. In other words from the moment you turn your computer on it will take a longer time for a copper heatsink to reach steady state conditions.

Now since these blocks have the same size they have the same surface area (that's what we're comparing, right - same size/shape/etc... heatsinks)

Now, that is really transient heat transfer, where there is a buildup of heat in one of the components of the system (the heatsink). At steady state, BOTH Al. and Cu. heatsinks will stabilize at a certain temperature and the heat per unit time (J/s = Q_dot) will be exactly equal to the heat leaving the heatsink per unit time. It will just take a longer time for the Cu one to reach this point.

2 processes going on:
(1) is conduction of heat through the heatsink
(2) is convection of heat from surface of heatsink to air

for conduction: Q_dot = (kAc/L)*(Tdie - Tsurface) <-- equation (1)here Q_dot is joules/second or Watts, k is the thermal conductivity of the material in Watts/meter*K, Ac is cross sectional area through the heatsink in meters^2, L is the lenth between Tdie and Tsurface in meters, Tdie is temperature at the die or temperature at the bottom of the heatsink (here we'll consider them equal) and Tsurface is the temp. at the surface of the heatsink, where the air contacts it. (temps in degrees C or K)

for convection: Q_dot = hA(Tsurface - Tair) <-- equation (2)
where A is the area of the surface of the heatsink (giving heat to the air) and h is the convection coefficient and has units Watts/meters^2*K.

from equation (1): Tdie = Q-dot * L/(k*Ac) + Tsurface
from equation (2): Tsurface = Q_dot/(h*A) + Tair

combining: Tdie = Q_dot*L/(k*Ac) + Q_dot/(h*A) + Tair

Taking the Tair, Across section of the heatsinks, A surface of the heatsinks, L length of the heat must travel between the die and surface, and Q_dot to be constant and the same in both cases (Ac, A, L wil be same because we are comparing the same heatsinks just of different materials, but the physical dimensions are the same, Q_dot is constant because the cpu puts out a fixed amount (ideally) say xxxWatts under load, and Tair is constant for it to be a fair comparison)

k for alum = 237 W/m^2*K
k for Cu = 401 W /m^2*K

--->You can see from the resulting equation that to make Tdie lower the only thing you can change is to make k, the thermal conductivity bigger - which is why COPPER WILL ALWAYS YIELD LOWER TEMPS FOR THE STEADY STATE HEAT TRANSFER.

Now, one more thing - after you turn your computer off, there is no more heat being put into the heatsink, and it is a possibility that the aluminum might cool down faster, but I'm not convinced of that yet. But who really cares then - the computer is off. All we really care about is steady state, which has been shown that copper will always yield lower die temps that for aluminum. (in the same situation, same mounting, same design heatsinks, etc....)

Also, anyone in this thread that hasn't looked over at the "Convection" thread by Neomoses also in the Technical Discussion Forum should give it a quick glance over.

Everything is done with respect with a cpu heatsink, but the physics all apply to any heatsink really.

Quote:
Originally Posted by qusp

nah copper makes a crappy heatsink, its great for sucking the heat out of the device, so a copper layer bonded to the AL is good, but on its own it has terrible heat dissipation, it would suck the heat out and hang onto it, then suck more out and get hotter and hotter and hotter. al is very good at getting rid of heat into the air, so a layer of copper with silver epoxy bonding it to an alloy heatsink is ideal and if that isnt possible, all al

Edited by Nebby - 10/27/10 at 3:27pm
Quote:
Originally Posted by yellowjeep

People have been doing it with computers for a long time, I mean you could even submerse the whole thing in mineral oil and it would work.  This whole thread is pretty crazy and I for one would love to see it come to fruition in one form or another.

I can see the headline now. House burns down from DIY'r amplifier. Cause due to reversed polarity of titanium electrolytic capacitor.

I don't see the correlation. I'm not trying to sound standoffish at all but if everything is on the built correctly there should be no issues. If I am missing something (which I easily could be) please explain.

Quote:
Originally Posted by IPodPJ

That's not what he suggested.  He said a relay based control.

Quote:

also, why not go with an LCD and remote for the volume and relay based source selection and get rid of that knob?

Alright guys I just turned on a lot of random electrical spinning crap (external HD, fan, dremel, sonicare) right next to my LD amp. It's no B22, but I didn't hear any hum through the headphones.

I'll get shielded toroids, I'll wrap the pump in a bunch of mumetal, and I'll put that mumetal shield around that compartment. If that still causes hum, I guess I'll commit seppuku or something for dishonoring the Gods of Head-Fi.

And as for worrying about the water, if custom computer builders aren't worried about ruining their thousands of dollars worth of CPU, motherboard, and GPU from a leaking cooling loop, then I don't have any reason to worry either.

Now to wait for myself to accumulate \$2000, my university department to fix their laser cutter, and Twisted Pear to re-stock the Buffalo. When will that happen? Don't know. Until then I'll be tweaking this and that and designing the internal structure and wiring layout (there are roughly 30 individual DC wires running up the central "core" area )

Crappy unfinished rendering:

Edited by haveblue - 10/27/10 at 11:37pm

Quote:

Originally Posted by yellowjeep

I don't see the correlation. I'm not trying to sound standoffish at all but if everything is on the built correctly there should be no issues. If I am missing something (which I easily could be) please explain.

Assuming that everything is built correctly is a very big assumption.  Not a knock against the OP - even the most experienced builders end up with complications.  Usually, the best approach is to simply things as much as possible.  If you use oil immersion, there's always a chance it could leak.  Shielding for RFI/EMI is a real bear, too.  You can't see it and it slips through the tiniest of cracks and wreaks havoc.  You might get a couple thousand into the project, a couple hundred hours, then discover that you can't square one system with another, or maybe the shielding isn't enough and the tolerance isn't there to add more, or something else entirely unexpected.  At that point, you'd either have to start over again from scratch or write off the project.

Also, let's say you use some company's proprietary parts or connectors for the cooling system.  OK.  It works well for a couple of years, then one of the connectors starts to leak or gets clogged or develops some kind of problem.  You plan to order a new one, only to find that the company stopped manufacturing them 18 months ago and has no spares, the company went out of business, etc.  Then you'd be stuck having to custom manufacture a replacement if you didn't want an expensive doorstop.

Personally, I'd put the power supply in a separate chassis and maybe make the back half (facing towards the wall) of the pyramid out of perforated aluminum.  That would significantly cut back on the engineering and make it a lot more likely to succeed.

Thanks Uncle Eric. All of that makes perfect sense, I was never saying I would but rather some in theory could. When inevitably have to build a b22 to call my own it will be as straight forward as possible.

I still think this is a neat project and I hope something comes from it. Water cooled or otherwise.

Uncle Erik, and everyone else who objects, I understand your concern for the potential failure of this project and both my financial and time investments. I'm weighing those risks against my perceived ability and am confident that I can pull this off. I admit that you have a lot more knowledge and experience in this field than I do, but your concern over EMI seems contradictory to the successful builds in amb's gallery.

Tell me why this guy isn't hearing any hum?

I don't think connectors and parts for CPU liquid cooling are going away anytime soon. I may as well plan for the obsolescence of XLR and RCA connectors.

http://www.frozencpu.com/cat/l2/g30/c409/list/p1/Liquid_Cooling-Fittings-Compression.html

I'm not the least bit daunted by the mechanical side of this project. If I can design 95% of this plane and then do 50% of the building myself, I think I can engineer this amp chassis. It doesn't need to fly, be under a certain weight, or carry any significant loads.

Edited by haveblue - 10/28/10 at 12:07am

Haveblue,

You seem very adamantly opposed to the suggestions other people here have offered you.

They wouldn't be telling you about hum due to close proximity of power supply and amp boards if there weren't known issues with it.

You come across like you know everything about how your amp will turn out when you've never built one before.

So best of luck to you and I wish you great success with your pyramid.

But you should probably stop wasting their time if you aren't going to seriously consider what's being said (especially from the designer himself),

which is sad because you could learn a lot from other members here that have built this amp.

Edited by IPodPJ - 10/28/10 at 12:22am

IPodPJ,

I am opposed to the suggestions because they contradict the seemingly successful examples in amb's gallery.

Nobody has yet answered my question that I have asked a good three times. How is my setup different and more prone to hum than a stacked two-box setup with the same physical distance between the transformer and B22 boards as compared to my design? If I wrap one of those setups together with duct tape, does that make it into a one-box unit (and therefore inducing hum)? Why does Tedro's unit not have any hum?

Edit: The only contributions you have made to this thread are an incorrect assumption on the safety of liquid cooling, and incorrectly pointing out an error on my reading comprehension on post #22.

I'm almost feeling that if anything unorthodox or radical is suggested around here that it is immediately shot down by purist old-schoolers.

Edited by haveblue - 10/28/10 at 12:43am
Quote:
Originally Posted by haveblue

IPodPJ,

I am opposed to the suggestions because they contradict the seemingly successful examples in amb's gallery.

Nobody has yet answered my question that I have asked a good three times. How is my setup different and more prone to hum than a stacked two-box setup with the same physical distance between the transformer and B22 boards as compared to my design? If I wrap one of those setups together with duct tape, does that make it into a one-box unit (and therefore inducing hum)? Why does Tedro's unit not have any hum?

Edit: The only contributions you have made to this thread are an incorrect assumption on the safety of liquid cooling, and incorrectly pointing out an error on my reading comprehension on post #22.

I'm almost feeling that if anything unorthodox or radical is suggested around here that it is immediately shot down by purist old-schoolers.

First of all, just because an amp is in the gallery does not mean that it's noise-free or should serve as an example as the "right" way to built an amp.  There is no "quality test" for any items in the gallery, all it takes is someone to send me some pics and descriptions to get in there.  There are some excellent builds in there, but there are also some that were built in a way that I would not have done.

Second, whether a particular amp exhibits audible noise depends on what headphones were used during evaluation.  Just because you can't hear noise with Sennheiser HD650s doesn't mean that it's going to be quiet with a Grado or Audio Technica.  You're building a top-end amp, and if I were you I'd want the amp to be quiet with any reasonable headphone.  Here are noise floor spectrum analysis graphs of two different amps, one with the power transformer near the audio circuitry and another similar amp with a separate PSU case.  The graphs are self-explanatory, but the noise is only barely perceptible through HD650s.

Amp with power transformer near audio circuitry:

Amp with separate PSU case, located a distance apart:

Thank you for that great explanation Ti.

Quote:
Originally Posted by haveblue

I'm almost feeling that if anything unorthodox or radical is suggested around here that it is immediately shot down by purist old-schoolers.

Leave Uncle Erik out of it! Have some respect.

Ti, on that test data above, could you roughly tell me how many inches is "near" and how many inches is "a distance apart"? Doesn't need to be exact.

And it is true that Toroids emit a stronger EMF toward their axes?

Edited by haveblue - 10/28/10 at 1:56am
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