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Old 18th November 2012, 04:34 PM   #7621
a.wayne is offline a.wayne  United States
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Unless you're thinking 1500 watts class-a dissipation why the trouble , heatsinks and fans work , without the complexity ....
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Old 19th November 2012, 06:18 AM   #7622
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Fans are noisy . Water might just be enough to allowing similar cooling from a compact box . The flaw in my TO 3 idea is the wrong side of the can is being cooled . It might be possible to seal the base emitter wires so as to totally immerse the device . I could imagine with FET's Ron could be made minimal if doing this . As DVV says a plastic device might work . It might dissipate a good amount of heat and what it looses by being insulated is gained in cooling on both sides .
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Old 19th November 2012, 07:46 AM   #7623
1audio is online now 1audio  United States
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You can get water cooling transistor bases for TO3's etc. They are usually copper and very good for removing heat. The computer water cooling kits would be a good start for the rest of the hardware. They have proven pretty reliable and not expensive (Newegg list 55 water cooling products, all less than $160 Newegg.com - Water Cooling, PC Water Cooling)

Or if you really want to do it right use the same method Cray used on super computers. Fill the whole box with Freon and pipe it to an external cooling system.
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Old 19th November 2012, 08:54 AM   #7624
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My son used a cooling kit for his computer . He paid a lot for having it look nice . If doing it from scratch I would recommend a small amount of the pink antifreeze used by VW ( 10 % ) to used as an inhibitor . Looking at the maths of this and interface it is like a thermal resistor added to the thermal circuit . Getting rid of it will be a big deal . If using oil it might even be worth removing the TO3 can top . Then the coolant is in direct contact with the silicon . It might work . I suspect if an oil change was performed after 1 week it would be helpful ?
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Old 19th November 2012, 12:58 PM   #7625
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A question which I am sure someone here will know the answer to . A friend has asked if it is possible to use notch filters to solve room resonance problems ? I got very complicated and said no . I argued we need a 24 bit ADC and be able to filter with zero phase shift sometimes ( or time of our choice ) .

Then I remembered another friend sold his services years ago in the music industry to solve the same problems in concert halls . His secret was to remove certain frequencies and not really to cure the acoustics . He would never tell me more . His idea being that some frequencies are not nice and others are . The customer thought he was getting one thing and was in fact getting another . Same frequencies for everywhere if I am right ? How much removed was dependent on the venue .

I know that some specialists do analyze rooms and treat them with mechanical resonant devices to do much the same thing . My instinct is to say that seems a better route ?

The question I am asking is . Can bog standard analogue notch filtering offer anything worth using in comparisons with digital domain solutions ? The friend in question made his living with vinyl records , I feel he would be hard to convince about a digital solution .

I did say to him if digital perhaps start with the very best digital recording/ processing we can . What is best now ? My feeling is 24 bit linear quantization may not be it ?

Perhaps my picture of this is a bit too complex ? Old horse drawn coaches had springs . Better that than nothing . Do analogue notch filters offer better than nothing ?
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Old 20th November 2012, 12:35 AM   #7626
1audio is online now 1audio  United States
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I introduced the idea of using a notch filter to control the impact of low bass in a room in the Entec subwoofer. The Entec had a tuneable notch from about 50 Hz to about 150 Hz. A sharp notch is inaudible in music, unless you listen to really boring pure tones. It was not possible to tune it by ear listening to music. With a sine wave generator it was pretty obvious but we recommended a radio shack slm to make it easier. The phase effects from the notch were not audible. The extra octave from getting rid of the dominant resonance between 120 and 60 Hz was dramatic. This was done almost 30 years ago with pretty simple analog notches. Depth did not matter much as long as it was pretty deep.

A DSP would be an easier implementation, if you have a GUI. otherwise 2 opamps would be more than enough to do the job.

The principle is that by removing the energy that would excite the room resonance the resonance will not build or cloud the other low frequency content. Using more than one notch in the LF might help but two filters close in frequency can cause weird things to happen so I never went too far down that road.
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Old 20th November 2012, 01:40 AM   #7627
Pano is offline Pano  United States
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Quote:
Originally Posted by SY View Post
Lots of hotrodders water cool their CPU, so I suppose you could call that a digital project.
Sorry, typo on my part. Should have read "digital projector".
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Old 20th November 2012, 02:03 AM   #7628
bcarso is offline bcarso  United States
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Quote:
Originally Posted by 1audio View Post
I introduced the idea of using a notch filter to control the impact of low bass in a room in the Entec subwoofer. The Entec had a tuneable notch from about 50 Hz to about 150 Hz. A sharp notch is inaudible in music, unless you listen to really boring pure tones. It was not possible to tune it by ear listening to music. With a sine wave generator it was pretty obvious but we recommended a radio shack slm to make it easier. The phase effects from the notch were not audible. The extra octave from getting rid of the dominant resonance between 120 and 60 Hz was dramatic. This was done almost 30 years ago with pretty simple analog notches. Depth did not matter much as long as it was pretty deep.

A DSP would be an easier implementation, if you have a GUI. otherwise 2 opamps would be more than enough to do the job.

The principle is that by removing the energy that would excite the room resonance the resonance will not build or cloud the other low frequency content. Using more than one notch in the LF might help but two filters close in frequency can cause weird things to happen so I never went too far down that road.
The man speaks sooth.
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Old 20th November 2012, 02:06 AM   #7629
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Here is an example: Altec 1653A. 31 notch filter in a box, all L-C. I used a pair of them before I bought that digital thingy Audyssey that does everything for me now. However it does not mean that any EQ can help with high Q resonances that decay long time.

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Old 20th November 2012, 02:16 AM   #7630
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Quote:
Originally Posted by 1audio View Post
A sharp notch is inaudible in music, unless you listen to really boring pure tones. <snip> Depth did not matter much as long as it was pretty deep.
How notchy are we talking? Do you remember Q and depth in ballpark figures at least?
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