John Curl's Blowtorch preamplifier part II - Page 1386 - diyAudio
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Old 13th July 2011, 03:23 AM   #13851
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We used a thick aluminum case, because it shields better than a thin aluminum case, AND it is less mechanically resonant.
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Old 13th July 2011, 04:06 AM   #13852
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Quote:
Originally Posted by john curl View Post
...AND it is less mechanically resonant.
Is it?

Bet if I hung it from a string and struck it it'd ring like a bell.

se
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Old 13th July 2011, 04:33 AM   #13853
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Hi,

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Originally Posted by Bonsai View Post
No need for a marketing lesson from you Torsten.
It seems you could use quite a few lessons in many areas.

BTW, non-linear effects in Fuses are well documented. The ones in series with drivers etc. show very measurable levels of distortion, quite possibly audible. Rail fuses can also increase measured HD appreciably.

Mains fuses, hard to say. However I do not presume to tell others what they can hear or not or insist that they must use generic fuses if they would prefer them gold plated and with fusible silver wire link instead.

You don't have to use them, or buy an AMP Phonostage or Amplifier or CD-Player etc.

Remember, you already have the best gear in the world, absolute perfection, completely incapable of being improved... So you don't need mine.

Ciao T
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Old 13th July 2011, 04:43 AM   #13854
FrankWW is offline FrankWW  Canada
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Is it?

Bet if I hung it from a string and struck it it'd ring like a bell.

se
But it's not hung by a string, is it? It's sitting on nice damping feet on a solid shelf and lots of mass should make it less vulnerable to sound vibration than flimsier enclosures.

I don't know why you get cranked by John or Thorsten designing luxury goods. There's no demand for anything until it's produced. They take their chances in the market and there's always a possibility of failure. And if you're in the luxury market, then you can't charge small change, even if that's what your costs are, cuz luxury buyers won't buy cheap. (They'll buy distressed, but the original price has to be high).
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Old 13th July 2011, 04:49 AM   #13855
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But it's not hung by a string, is it? It's sitting on nice damping feet on a solid shelf and lots of mass should make it less vulnerable to sound vibration than flimsier enclosures.
If the thinner enclosure is sitting on the same shelf with the same feet, how is it any more vulnerable to vibration?

Also, what John stated the chassis itself was less resonant. How is it less resonant?

Quote:
I don't know why you get cranked by John or Thorsten designing luxury goods.
Where have I said anything about anyone designing luxury goods?

John said the thicker chassis was less resonant. I'm simply asking him how exactly it's less resonant than a thinner chassis. What's that have to do with luxury goods?

se
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Old 13th July 2011, 04:55 AM   #13856
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When I go to a manufacturers trade show I see a lot of metal cases. Some cast, some hogged, some made in other ways. We have looked high and low for a CHEAPER way to make a case with the same qualities, ie ruggedness, finish-able, and finally passing the FINGERNAIL TEST. Just take your fingernail and click it against the side of a candidate. This will tell you whether it is high Q, or well damped. Try it on your equipment at home.
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Old 13th July 2011, 05:02 AM   #13857
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Quote:
Originally Posted by john curl View Post
When I go to a manufacturers trade show I see a lot of metal cases. Some cast, some hogged, some made in other ways. We have looked high and low for a CHEAPER way to make a case with the same qualities, ie ruggedness, finish-able, and finally passing the FINGERNAIL TEST. Just take your fingernail and click it against the side of a candidate. This will tell you whether it is high Q, or well damped. Try it on your equipment at home.
Well damped? Where's the damping material? I don't recall seeing any inside the chassis.

Click the image to open in full size.

Again, hang it by a string and strike it. It'll ring like a bell.

se
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Last edited by Steve Eddy; 13th July 2011 at 05:05 AM.
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Old 13th July 2011, 05:32 AM   #13858
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Perhaps, Steve. And perhaps not. Everyone else, just tap your audio and video equipment with your fingernail and hear what happens.
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Old 13th July 2011, 05:43 AM   #13859
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It is interesting to see the input of one of my preamps. I have never opened my own, but it would look almost exactly like this picture. You are looking at it upside down. The Vendetta boards are on the left, with Teflon Eq caps. The line amp boards are on the middle right are are made of Teflon. Each module has its own dual DC regulator or cap multiplier. DC only comes in from the middle back connector that has multi-pins. There are four separate regulators in another almost identical box that convert AC to dc for each gain block. All of the wiring is pure silver that we used to be able to buy at a significant price to us. Unfortunately, it is unavailable at this time. I wish that I would have stocked up.

Last edited by john curl; 13th July 2011 at 05:57 AM.
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Old 13th July 2011, 05:54 AM   #13860
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A little more: the yellow caps are Rel RT polystyrene caps. They are very well 'damped' just like the case. The electrolytic caps are Nichicon Muse, non-magnetic leaded caps. The red caps are Panasonic and used only for the servos. (lots of servos)
The big switch is to reverse the polarity of the output.
The volume pots are TKD, a rather expensive pot that costs us almost $200 ea. However it is better than making them ourselves, at least from our point of view. '-)
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