John Curl's Blowtorch preamplifier part II - Page 2807 - diyAudio
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Old 10th October 2012, 04:01 PM   #28061
morinix is offline morinix  United States
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John, With $3k chassis an $50 x 100 PCB's and god knows what else; How did you afford to stock parts inventory?
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Old 10th October 2012, 04:13 PM   #28062
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That is why the CTC Blowtorch was so expensive to make. We went for the BEST that we knew that was available. It cost us plenty, but we tried to keep the ultimate price reasonable by selling DIRECT, no dealers in the USA. However, offshore importers, like the Japanese could mark up the design to whatever they thought the market would bear. They went with with 5,000,000 yen, or about 5 times the price we sold it to them at. That's a real problem with offshore importers, they may have the customers, but the customers pay MUCH more than if they bought it in the USA.
I am struggling now with a problem that would have seemed to have an obvious solution, perhaps 20 years ago, but is amazingly difficult to solve.
For ULTIMATE MC input loading, I thought that a 10 turn, wirewound pot would be the ultimate in linearity and sophistication. This could be tracked by an added pot that could lead to a read-out so the customer would know what the loading resistance was, and it could be controlled by remote control. This would give the listener a chance to 'dial in' the actual load resistance from the listener's position, an ideal way do doing it. So far as we can estimate, it will cost us a few thousand dollars OEM to do this right. What a headache!
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Old 10th October 2012, 04:21 PM   #28063
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Why is that so expensive John? I can understand that you want a very good wirewound, but the 2nd pot can be a linear pot running on a DC voltage, with the wiper DC into a PIC's A/D converter and into a standard A/N display. You can put a cal or translation table in the PIC.
The PIC can also do reception and decoding of the remote signal and drive a small DC motor for the wirewound.
That part of the system should not set you back more than perhaps $70 or $80 tops.

jan
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Old 10th October 2012, 04:21 PM   #28064
marce is offline marce  United Kingdom
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The types of FR4 available today are totaly different from what they were years ago. With the advent of lead free soldering and the increase in process temperatures, plus the ever increasing high speeds of digiatl signals, the ever decreasing supply voltages etc you cannot reference designs and materials from 25 years ago today. There has also been many changes in the glass weave in FR4 from the horrible 1080 of years ago to todays laminates designed for high temps (Tg 170) and high speed designs.
If you want to achieve he best possible design be it digital or analogue you are better of looking at the layout rather than base materials, we use FR4s for most of the designs we do, and probably 95% of all he ones we do use FR4, these are designs for a whole host of curtomers many of them medical, areospace and military designs. Using exotic materials adds other problems and cost for no benefit.
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Old 10th October 2012, 04:32 PM   #28065
bcarso is offline bcarso  United States
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Originally Posted by marce View Post
If you want to achieve he best possible design be it digital or analogue you are better of looking at the layout rather than base materials, we use FR4s for most of the designs we do, and probably 95% of all he ones we do use FR4, these are designs for a whole host of curtomers many of them medical, areospace and military designs. Using exotic materials adds other problems and cost for no benefit.
Why do you imply that we are neglecting layout?
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Old 10th October 2012, 04:53 PM   #28066
marce is offline marce  United Kingdom
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Why do you assume that, I cant understand some replies, or the paranoia in the replies!
i am just giving some advice like many others do on this forum. PCB design just happens to be my area of expertease, and I am pretty much an expert in the design and assembly of PCB's and most aspects sourounding them.It does get my back up though when you get replies like yours Bcarso, I was not implying anything, so why reply in such a way, take a chill pill as my Kids would say
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Old 10th October 2012, 05:06 PM   #28067
jcx is offline jcx  United States
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few nodes in a amp are high enough impedance for the pcb dielectric nonideal behavior to have any effect

those few can be often be guarded - the same layout used for pcb leakage current bootstrapping at high Z also provides dielectric C bootstrapping

for low production exotics or hobby amps press in teflon standoffs or air wiring sensitive nodes can work too where a few hand soldering operations doesn't blow the budget


another modern option is multilayer with the teflon only on the outer layer - with smt you may be able to keep sensitive nodes entirely on the surface of the "good" dielectric

Last edited by jcx; 10th October 2012 at 05:11 PM.
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Old 10th October 2012, 05:08 PM   #28068
morinix is offline morinix  United States
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Electro Guru's, I still want to know why a Tek scope-like chassis is not good enough technology to house a Blowtorch?

Can't we all just get along?
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Old 10th October 2012, 05:28 PM   #28069
SY is offline SY  United States
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Quote:
Originally Posted by morinix View Post
Electro Guru's, I still want to know why a Tek scope-like chassis is not good enough technology to house a Blowtorch?
Because it's not impressive-looking enough.
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Old 10th October 2012, 05:38 PM   #28070
morinix is offline morinix  United States
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Because it's not impressive-looking enough.
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