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    Building, troubleshooting and testing of these amplifiers should only be
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Simplest or easyest dc filament supply for 300B

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#64
gillougillou said:
Hello, yes I will be pleased to find The path to thé boards

Thanks

Gilles
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No problem Gilles.

There's a long thread about them (development/testing/use) here;

DHT Heater using VCCS - PCB or Kit (Possible Group buy) - audio-talk

and some reference material here;

DHT Heater Group Buy notes. - audio-talk

There are two versions of the board, 'Large' and 'Small' though the PCBs are of similar size, the difference is that the small has an onboard heatsink (like the ones I use) whereas the large is designed to have the active devices attached to a chassis heatsink and can deliver more current.

Note that the designer, forum user 'Andrew' has not published a schematic but sells PCBs (at a very reasonable price) - you can build the PCBs up using the BOM and reference information. Note that the parts on the BOM were carefully selected through extensive listening tests.

I'm happy to assist with getting PCBs if you are interested?

Ray
 
#66
nautibuoy said:
...300Bs tend to carry a premium price tag...not saying that simple/easy and best are necessarily mutually exclusive.
Click to expand...
In Robert Pirsig's famous novel "Zen and the Art of Motorcycle Maintenance", there's a section where the protagonist / narrator and his non-technical friend John Sutherland are out on a long cross-country motorcycle trip.

John has an expensive BMW bike, and the handlebars are beginning to slip, and he's starting to worry about it, because they're way out in the boonies with no BMW mechanics for hundreds of miles around.

The narrator of the book (John's riding companion) tells John not to worry - all John's bike needs is a shim installed where the fork meets the handlebar, and he has the perfect shim material at hand. In response to John's enquiring look, the narrator holds up his beer-can, and points out that the thin, soft aluminium the can is made from is the *perfect* handlebar shim.

John is quite insulted at the idea of sullying his precious bike with a piece of beer-can metal. The narrator is completely unable to understand this - a piece of beer-can really IS the perfect shim material. Why can't John see this?

That's exactly the situation we're dealing with here. The 300B in this thread is the same thing as John's precious BMW - more a sacred religious symbol than an engineering artifact. As such, a pragmatic engineering repair is sacrilege and shocking. What's required is a properly sacred repair. Sacred requires lots of money, and involves lots of other ancient religious icons, such as iron-core chokes. 🙂


-Gnobuddy
 
#67
I understand your reference very well and if I were in that situation I would use the beer can solution, however, we're not in the middle of nowhere needing to fix a slipping bar or anything analagous to it.

To be honest I'm not really sure why you're troubled by somebody posting about something different to the solution you're espousing and, to be frank, I can't really be bothered with it.

All I'll say is that I have filament supplies that use a different approach to yours. They're not based on any pseudo religious beliefs and can be used with a wide range of DHTs (I plan to try them with 4P1Ls sometime). I've used various filament supplies and have settled on the ones I use as performing best in my 300B amps within my budgets (they're actually pretty small and low cost) - YMMV. Happily, I'm allowed to do that. I'm willing to share information on the boards I've used to anyone who has the curiosity to find out more and maybe try them.
 
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#72
Who is going to read through 537 posts to see the history and derivations that got to # 532 and # 537?

Are we wanting to answer this post about DC for 300B filament,
Or are we looking for a continuation of the DNoizator thread?
 
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#74
nautibuoy said:
...I'm not really sure why you're troubled by somebody posting about something different to the solution you're espousing
Click to expand...
Firstly, this has nothing to do with any of the specific old-fashioned solutions that were posted, yours or anybody else's.

Secondly, "troubled" is not exactly the right word; but I'm always intrigued (and yes, to some degree, saddened) when humans abandon reason and logic and knowledge and substitute emotion and tradition and precedent.

It's a personal anthropological study of sorts, a study of a quite widespread phenomenon that has caused humanity a great deal of suffering throughout history.

And now I'll be off to sacrifice a lamb to the Gods, and pray to them to stop the Coronavirus epidemic.


-Gnobuddy
 
#76
Moving us all back to the Original Post:
Simplest or easyest dc filament supply for 300B.
What would be the easiest way to make a filament DC 5V for a 300B ?

How about doing this:
A 6.3VAC secondary, Schottky Bridge, 22,000 uF cap, 2 ohm 20 Watt resistor, 22,000 uF cap.
Parts count: 5, including a 6.3V secondary.
Simple?
You be the judge.
 
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#79
How many parts are in an SMPS?
Maybe you did not build it, but somebody did (or a pick and place machine did).
Transistor, diode, coil, PCB, resistor, capacitor, connector, . . . .
Some are quiet, and some are noisy.
Take a CD player that has super-audio spurs (not a problem by itself), and beat those with switcher spurs, then intermodulate the two, and you have spurs folded back into the audio band.

5V batteries are hard to come by.
A 6V lantern battery and a resistor will only take 2 parts to get 5V, and then 3 parts, and then 4 parts, and then . . . every time you replace the lantern cell.
And just try and find a place that will recycle all those lantern batteries for you.
environmentally responsible?

The above are 'Simply' my opinion.
 
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#80
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