My GSG Mods

[kku]

I've definitely seen a number of tube amps use the large oil filled polypropylene caps in power supply filter applications. http://www.partsconnexion.com/capacitor_film_asc.html ASC in particular seems to be pretty common. The 120uF caps are not completely in parallel though, R17 sits between the positive legs (either a pair of resistors or a choke), so I don't know if you could have different values on each side. I'll have to leave that question to the experts

http://www.tubelab.com/AssemblyManualSi ... ic_SSE.htm

In Tubelab SSE, the PS has similar thing going on; the choke is it between 2 major power caps. C1 is 47uf and C2 is 120uf. And the motor run is in parallel with 120uf cap.


GSG:
C10 is the 22uf cap. C8 and C9 are 120uf caps and R17 sits between them. I was wondering about putting a 80uf(or may be smaller value) motor run cap in parallel with C9 and entirely replacing C10 with a 20-30uf motor run. I wonder what the experts think aswell.

[Shannon Parks]

Motor run caps aren't my style, but what you propose is fine. The values you suggest seem right on. The key is to not stress the tube rectifier with too much inrush current by keeping within standard capacitance values.

Shannon

[BruceAnderson]

Well of course I wasn't really and finally done with my Get*Set*Go mods. I recently completed the "Western Electric Aikido" mod which I recommend as absolutely manditory. See: www.tubecad.com/april99/page2.html. You probably want to go thru all three pages and maybe even do all the calculations but I will cut right to the chase. I went out to the garage and shuffled thru a big box of motor run caps from Apache Reclamation in Phoenix and pulled out two 20uf 370VAC ones that have just been waiting for me for years. One terminal connects to J7 (B+ output). The other terminal connects to R15(A, B or C). The other cap terminals connect to J7 and R16(A, B or C). R15 and R16 legs closest to the center of the board are grounded. You want to attach to the other side, closest to the edge of the board. That's all there is to it.
What's the result? The amp is no longer very quiet compared to other DHTSE amps. It is very quiet compared to push/pull indirectly heated or even SS amps. Although Broskie doesn't get into it there are numerous comments on the net claiming this change will (or will not) shortcut current flow and therefore dodge the "evil" effects of electrolytic power supply caps. You decide. Me, I'm too busy playing recording after recording

[battradio]

I got a hold of some 600UF 500 volt poly lighting supresion caps with very low ESR's that i will be usinig in my next build .

[img][img]http://i650.photobucket.com/albums/uu227/battradio/three/Wire/Pre/ASC001.jpg[/img]


These caps are basicly 600 uf orange drops and very large .

The simulation in the Duncan program looks vey nice .

The ESR is tested a 100khz so they are low impeadance across the audio spectrum , will be using motor run caps for the first cap but being before the 11hy choke it shouldn't have much influance over the impeadance of the power supply .