I high value the contents posted on this forum and over the years it has been very helpful as I learn the art of building tube gear. I currently have a pair of Dynaco MKIIIs which I rebuilt from scratch about a year ago using the original circuit design and am happy with the result. Now, I'm ready to build my next project which is a 300B SET amp.
The circuit I have my eyes on is from a 2001 Japanese tube magazine, unfortunately, I don't understand Japanese so basically, I've been using it as a reference design and comparing it against what I could find from other people's 300B SET design on the net and comments made on this forum and making notes for myself along the way so that hopefully I can improve it for my own project...
I would like to solicit opinions from my fellow members about this design so that hopefully others can find merits with this design and build one for themselves...
For starters, the following is what I like to improve from the present design:
1] modify the HUM circuitry using 100 ohm 2W pots for minimum hum
2] Introduce B+ delay circuit with in-rush current thermistors as outlined in Pete Millet's site for a prolonged tube life
3] decouple 6.3 AC heater from the B++ circuit. I'm not sure what was the idea behind tying the two together.
4] I plan to use polypropylene coupling cap in prepamp stage one (C101) and paper in oil in pre-amp stage two (C103)
Once I'm done building this amp in phase 1, I plan on revisiting this design and further fine tune it perhaps using other pre-amp tubes.
Thanks for reading.
Norm
The circuit I have my eyes on is from a 2001 Japanese tube magazine, unfortunately, I don't understand Japanese so basically, I've been using it as a reference design and comparing it against what I could find from other people's 300B SET design on the net and comments made on this forum and making notes for myself along the way so that hopefully I can improve it for my own project...
I would like to solicit opinions from my fellow members about this design so that hopefully others can find merits with this design and build one for themselves...
For starters, the following is what I like to improve from the present design:
1] modify the HUM circuitry using 100 ohm 2W pots for minimum hum
2] Introduce B+ delay circuit with in-rush current thermistors as outlined in Pete Millet's site for a prolonged tube life
3] decouple 6.3 AC heater from the B++ circuit. I'm not sure what was the idea behind tying the two together.
4] I plan to use polypropylene coupling cap in prepamp stage one (C101) and paper in oil in pre-amp stage two (C103)
Once I'm done building this amp in phase 1, I plan on revisiting this design and further fine tune it perhaps using other pre-amp tubes.
Thanks for reading.
Norm
