John Curl's Blowtorch preamplifier part II - Page 2806 - diyAudio
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Old 9th October 2012, 08:08 PM   #28051
wayne is offline wayne  United States
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This is OT but I thought this would be a good place to ask. Any recommendations on high performance PC board materials from Rogers, Isola etc?
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Old 9th October 2012, 08:34 PM   #28052
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Yes, Rogers. You'll find many options depending on your requirements.
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Old 9th October 2012, 09:17 PM   #28053
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Originally Posted by wayne View Post
This is OT but I thought this would be a good place to ask. Any recommendations on high performance PC board materials from Rogers, Isola etc?
Nelco 4013-SI and Panasonic Megtron 6 are pretty much at the top these days. Rogers popularity for very high performance applications has declined, particularly with the introduction of the newer Megtron 6. Both Nelco 4013 and Megtron 6 are robust to the higher reflow temperatures of ROHS 6/6 lead-free processes, while most Rogers is marginal in that regard. Rogers is playing catch-up now. Nelco 4013 and Panasonic Megtron 6 are both less expensive than Rogers. All specs that I am aware of for Megtron 6 are the equal of Rogers to 10 GHz. Most systems in which 28 Gb/s signals are routed on copper traces utulize Megtron 6 nowadays.

Cheers,
Bob
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Old 9th October 2012, 09:31 PM   #28054
wayne is offline wayne  United States
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Thanks for the board materials input! Always a few experts here.
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Old 10th October 2012, 12:22 PM   #28055
marce is offline marce  United Kingdom
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Good quality FR4 would do the job, PC boards aint up in the high GHz region so you dont realy need exotic materials and probably wont get much benefit out of them. What you need to make a PC motherboard design as quiet as possible is a good layer stack up, and good layout and routing, especialy the SMPS. Also decoupling properly using power integrity simulation software helps. The main power plane layers should be closely coupled, and here is one area where a better dialetric would pay of, to maximise he planar capacitance as this provides the instantaneous switching supplies, long before any decoupling capacitors.Standard PC motherboards are layed out with the minimum number of layers to cut costs, quite often 6-8, for signal integrity and noise suppression they should have at least 12. But the best layout technique is HDL, plenty of info in this if you realy want to create the quietist design:
The HDI Handbook
A lot of consumer products (apple included) use this for of layout with the smallest possible packages, so you get the smallest loops, in built shielding with HDI and the right number of layers for signal integrity.
There is no free meal with PCB design, using more exotic materials adds other problems to your design criteria.
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Old 10th October 2012, 12:29 PM   #28056
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Slightly OT:

If any of you guys plan to come to Denver this weekend for the Rocky Mountain Audio Fest, be sure to stop by our little audio diy booth in the lobby (behind the registration counter).

We'll have a shared booth from Elektor USA, AudioXpress and Linear Audio.
Bob Cordell will be there showing his VinylTrak phono/preamp.

Be sure to stop for a light chat or serious diyaudio business

We'll be there the whole show.

jan didden
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Old 10th October 2012, 12:32 PM   #28057
SY is offline SY  United States
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Will Bob's preamp fit in your suitcase?
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Old 10th October 2012, 01:23 PM   #28058
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Originally Posted by janneman View Post
Slightly OT:

If any of you guys plan to come to Denver this weekend for the Rocky Mountain Audio Fest, be sure to stop by our little audio diy booth in the lobby (behind the registration counter).

We'll have a shared booth from Elektor USA, AudioXpress and Linear Audio.
Bob Cordell will be there showing his VinylTrak phono/preamp.

Be sure to stop for a light chat or serious diyaudio business

We'll be there the whole show.

jan didden
I'm really looking forward to seeing Jan and all the other folks who are fortunate enough to make it to this great audio show. My friend Peter Smith will also be there.

For those of you interested in the Linear Integrated Systems line of JFETs, I believe Paul Norton will also be at RMAF.

Cheers,
Bob
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Old 10th October 2012, 01:55 PM   #28059
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Will Bob's preamp fit in your suitcase?
Of course...
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Old 10th October 2012, 03:38 PM   #28060
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I would like to follow up on board material. Almost 40 years ago, Tektronix found a problem with FR board material. They had trouble making resistive attenuators because the board material had a significant amount of dielectric absorption. They called this problem, 'circuit hook'.
At Vendetta Research, about 25 years ago, we started with FR-4, but then we went to a 'better' material, (certainly more expensive, with better specs) and we got a subjective improvement. Then when we made the CTC Blowtorch boards, we went to Teflon. Each small board then cost us about $50ea in lots of 100, to make, but I am not sorry that we did so.
Today, FR-4 is OK for most applications, but I still hope for better. Is Teflon worth it? I am not sure, but it sure didn't hurt us in achieving our goal.
I now have the same questions about Polystyrene and Teflon. Is one really better that the other for audio applications? I really don't know for sure.
Most mid-fi seems to use something cheaper and smellier than FR-4. I would not use it for hi end, myself.
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