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Old 4th February 2008, 02:22 PM   #1991
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Quote:
Originally posted by Babowana
Thanks for the very interesting info.
When I saw your additional caps first, I thought them just as
a simple reinforcement for cleaner dc-supply. But, they seem to
be doing more work than expected.

I also try to find the sweet listening spot, moving my seat around
as you do, for serious listening. Your variation is quite simple and
seems to be worth trying . . .

No pre? If you like tube sound, I would like to inform you that
the good parts of tube pres are well powered by F4 . . .

Hello Babowana,

Paraphrasing Carpenter: “Isn't it amazing how a few of capacitors can organize your world“. In the past, applying additional capacitors as close as possible to supply legs of digital and analog IC’s, I made sound improvements of my CD player.

Regarding pre and tube sound – to be frank wit you I do not know how tube sounds. Some friends tells me: Andrzej, forget transistors, focus on tubes. But I do not like high voltages...

Best Regards,
a.
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Old 4th February 2008, 02:24 PM   #1992
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Carpenter,
How is your painful arm?
a.
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Old 4th February 2008, 03:56 PM   #1993
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Quote:
Originally posted by Andrzej Sochon
Carpenter,
How is your painful arm?
a.

My shoulder is improving--thank-you for asking.

I've been putting the finishing touches on my DIY hobby room. It's giving me plenty of exercise. Cabinets installed, now I'm loading them up with all my diy parts, books, and equipment... I'm very happy.

Maybe this month I can go back to work.
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Old 4th February 2008, 06:16 PM   #1994
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by carpenter



My shoulder is improving--thank-you for asking.

I've been putting the finishing touches on my DIY hobby room. It's giving me plenty of exercise. Cabinets installed, now I'm loading them up with all my diy parts, books, and equipment... I'm very happy.

Maybe this month I can go back to work.

give us piccies of new hobby room ;

if ya think that here is inappropriate - just post them in any - ya know which one(s) - thread
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Old 4th February 2008, 06:40 PM   #1995
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Quote:
Originally posted by Zen Mod



give us piccies of new hobby room ;

if ya think that here is inappropriate - just post them in any - ya know which one(s) - thread

You mean the OT mob thread? Hahahahahah..........

I'll get some soon. Thanks for letting me show-off a little.
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Old 5th February 2008, 07:49 PM   #1996
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Quote:
Originally posted by cviller
I'm afraid you can't think of them as dc stable sub-rails - it is a trick by NP to make life a little easier on the jfets. If you don't end up with a ground loop, I think you get 6db attenuation with this configuration, the output decoupling however should be perfectly fine!
Hello Cviller,

You are right, my input capacitors provide an AC output to the input GND. I focused on various versions of f4 schematics. I have difficulties in understanding all aspects of f4 schematics, especially at higher frequencies, having no laboratory equipment.

I also found Mr. Nelson Pass very interesting comments regarding bootstraping and improving frequency response (posts #397, 416, 426). Let me ask a risky question: what is an influence of PC board design? Maybe bootstraping and 1K resistor in series with the C3/C4 caps – maybe this is panacea for frequency response in this particular case of NP PC boards design. I see there are few very long paths here (f4 User and Service Manual). Long parallel near (close) paths may create problems at higher frequencies, I don’t know if 1 MHz is enough or not. I am sure Mr. Pass could tell us many interesting stories about how his projects behave at high frequency. (Long time ago somebody told me that it is much easier to make generator than an amplifier).

In comparison Peter Daniel boards (amp) are very compact, they have rather short paths. Did somebody try to analyze or measure frequency response of f4 build on Peter board? My risky question comes again: does f4 depend on board design? If yes, maybe bootstrapping and hi frequency peaks compensation are not always necessary. I will appreciate very much Mr. Nelson Pass opinion.

I remember somebody asked a question regarding oscillations observed on oscilloscope. What are the final results of his tests? Was it NP PC board design or Peter Daniel, how the sound results are? Could you remind me?

Apart from anything else I like NP boards and housing design very much, all is very clear, all parts are easy available, not like at my deep cramped tunnel, see my avatar.

Best Regards,
a.
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Old 5th February 2008, 11:56 PM   #1997
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Andrzej,
Amazed you actually use those sinks this way around - try turning them "inside out" (fin in)and cool the assembly with a slow running, quiet computer fan and add a temp control cct for faster, more accurate pwr fet temp setting - plenty of examples.

There are any number of cheap fans like Cool-Master, Nexus, etc and mount with soft rubbers, add a 40mm fan to h.sink space, ensure no sharp edges, etc.

I've thought about using the larger, high flow, low turbulance fans which are "totally" silent but quite expensive and require a better system of temp/power control, unfortunately, so still using the C.Masters - silent in use, with baffle plate.
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Old 6th February 2008, 07:34 AM   #1998
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Quote:
Originally posted by jameshillj
Andrzej,
Amazed you actually use those sinks this way around - try turning them "inside out" (fin in)and cool the assembly with a slow running, quiet computer fan and add a temp control cct for faster, more accurate pwr fet temp setting - plenty of examples.
Hello JH,

Thank you very much for fantastic idea with turning sinks - my cables are long enough.
In the past SOZ was inside, including typical computer fan at the top. I even applied simple electronics with thermistor to slow down propeller after a cold start. I will use it again.
Best Regards,
a.
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Old 7th February 2008, 02:38 AM   #1999
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I tried a fan cooled amp, I found with a extra quiet fan for HTPC's it to be to loud. I tried slowing it with a PWM controller and the controller put a heck of a racket on the AC mains. Gave up on it and salvaged the power supplies for F4 amps.
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Old 7th February 2008, 02:46 AM   #2000
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Put them in a pair of these:
I have to admit these are the best sounding amps I have built. The sound stage on these are phenomenal. My Aleph30 goes into the closet with my 300b set amps, and a pair of KT88 amps.
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