how to correctly design power supply filtering

[wsaraceni]

im looking at a bucket of parts i have leftover from various projects, and im looking at various schematics to see what i can build out of it. i somewhat understand the tweaking of values in the preamp, but dont totally understand the values in the power supply. im thinking of building a single ended amp. not necessarily anything existing, just to tinker around

for example, im looking at the dr z mini z. site. the power supply has a 40uf and 2 20uf caps. a fender champ has a 16uf and 2x 8uf. you get the idea.

so im trying to build a simple, diode rectified, single ended el84, with one 12ax7 and a volume (maybe a tone) and thats it. i have a 125DSE output transformer and a 269EX power transformer. and a decent selection of caps and resistors. where do i go from there.

[selloutrr]

it depends on the current your tranformer puts out and the amount you want to send to the circuit. After that it's filter clean and how much bass you want. I'm sure someone here has a computer program that will fill in all the what if's for you.

there are some great books on amazon and tubesandmore.com that can answer most if not all of your questions. you may also want to try the library or radio shack.

[wsaraceni]

thanks. im sure its pretty simple once you understand it. what books would you recommend?

[selloutrr]

The Art of Linear Electronics
By John Linsley Hood

Principles of Power
A Practical Guide to Tube Power Amplifier Design
By Kevin O'Connor

Beginner's Guide to Tube Audio Design
By Bruce Rozenblit

[Aurora]

Duncanamps PSU designer is free download. You need to understand at least basic PSU design, though, to fiddle the data correctly. Scroll down or PSU II

http://www.duncanamps.com/software.html

There's also loads of books and stuff available on the net. Look in Garage Talk - Reading material on steroids

[Structo]

A couple sites with good info.

http://www.freewebs.co.uk/valvewizard/index.html

http://www.aikenamps.com/

http://www.geofex.com/

The Tales From The Tone Lounge site is also good but you have to wade through a lot of opinions.
http://www.tone-lizard.com/Table_Of_Contents.htm

A couple of Gerald Weber books aren't bad

http://www.amazon.com/Tube-Guitar-Ampli ... 0964106027

http://www.amazon.com/About-Vacuum-Tube ... pd_sim_b_1

http://www.amazon.com/Tube-Talk-Guitari ... pd_sim_b_5

Dave Hunter Book
http://www.amazon.com/Guitar-Amplifier- ... y_b_text_b

Aspen Pittman of Groove Tube fame latest edition has a lot of schematics and info.
http://www.amazon.com/Tube-Amp-Book-Rev ... pd_sim_b_3

[dartanion]

Since you are going with an SE design and SS diodes, the first filter node can be anything. With a tube rectifier, you need to follow what the datasheets say to a certain degree. As well, with SE amps, hum can be an issue, so having extra filtering is a good idea. I usually add another node just after the rectifier, eg. if the original circuit was say 33>22>22, I change it to 33>33>22>22. Other than that, just know that increasing the filtering for different nodes changes the tightness/looseness of each stage. I would also recommend connecting the filament CT to the tube side of the cathode resistor on the power tubes to elevate the filaments above ground potential to reduce hum even more. Additionally, you can create an elevation circuit if you need to raise them further from ground. Alternatively, you can also go with DC filaments, which should eliminate hum.

I would recommend starting with a Champ like design adapted for an EL84. Then tweak to taste. FWIW, most Champs were grossly under filtered.